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Photodynamic therapy (PDT) is an effective noninvasive therapeutic strategy that can convert oxygen to highly cytotoxic singlet oxygen (1O2) through the co-localization of excitation light and photosensitizers. However, compromised by the hypoxic tumor microenvironment, the therapeutic efficacy of PDT is reduced seriously. Herein, to overcome tumor-associated hypoxia, and further achieve tumor-targeted synergistic chemotherapy/PDT/photothermal therapy (PTT), we have constructed a biodegradable oxygen-producing nanoplatform (named Ini@PM-HP), which was composed of the porous metal-organic framework (PCN-224(Mn)), the poly (ADP-ribose) polymerase (PARP) inhibitor (Iniparib), and the polydopamine-modified hyaluronic acid (HA-PDA). Since HA can specifically bind to the overexpressed HA receptors (cluster determinant 44, CD44) on tumor cell, Ini@PM-HP prefers to accumulate at the tumor site once injected intravenously. Then iniparib can be released in tumor environment (TME), thereby dysfunctioning DNA damage repair and promoting cell apoptosis. At the same time, the chelating of Mn and tetrakis(4-carboxyphenyl) porphyrin (Mn-TCPP) can generate O2 in situ by reacting with endogenous H2O2, relieving the hypoxic TME and achieving enhanced PDT. Moreover, owing to the high photothermal conversion efficiency of PDA, PTT can be driven by the 808 nm laser irradiation. As systematically demonstrated in vitro and in vivo, this nanotherapeutic approach enables the combined therapy with great inhibition on tumor. Overall, the as-prepared nanoplatform provide a promising strategy to overcome tumor-associated hypoxia, and shows great potential for combination tumor therapy. Statement of significance A delicately designed biodegradable oxygen-producing nanoplatform Ini@PM-HP is constructed to achieve combination therapy of solid tumors. Taking advantage of the active-targeting, PTT, enhanced PDT and PARPi, this nanotherapeutic approach successfully enables the combined chemo/photothermal/photodynamic therapy with great inhibition of solid tumors.

Background: Triple-negative breast cancer (TNBC), the most common type of breast cancer, is associated with poor patient prognosis. Platinum-containing chemotherapies are commonly used in the treatment and prevention of advanced TNBC. Objectives and Methods: To systematically evaluate the effectiveness and safety of platinum-containing chemotherapies in patients with advanced TNBC, we searched several databases, including PubMed, Medline, Embase, ClinicalTrials.gov, Cochrane Library, CNKI, CBM, and the Chinese Cochrane Center, to collect published randomized controlled clinical studies of platinum-containing chemotherapies for advanced TNBC before November 2020. The meta-analysis was performed using Review Manager version 5.3. To assess effectiveness and safety, dichotomous and continuous variables were assessed using odds ratio (OR) and mean difference (MD), respectively, with 95% CI. Results: A total of 1,222 patients with advanced TNBC were enrolled in 11 eligible trials, including 489 patients in the treatment group (platinum-containing) and 447 patients in the control group (non-platinum-containing). We also retrieved information whether a PARP inhibitor was combined with platinum-containing chemotherapy for patients with metastatic TNBC and identified 224 patients who received a PARP inhibitor combined with platinum-containing chemotherapy and 62 patients in the platinum-containing group who did not. The platinum-containing chemotherapy group had a significantly better objective response rate (OR 1.43, 95% CI 1.20–1.71, p < 0.001) and longer progression-free survival (PFS; MD 1.15, 95% CI 0.03–2.28, p < 0.05) than the non-platinum-containing chemotherapy group. However, there was no significant difference in overall survival (OS) of patients with advanced TNBC between the two groups (MD 2.04, 95% CI –0.83 to 4.91, p > 0.05). Related adverse effects of platinum-containing chemotherapies involved gastrointestinal reaction, myelosuppression and liver function damage. Platinum-containing chemotherapies were not associated with an increased incidence of adverse side effects compared with non-platinum-containing chemotherapies, with the exception of nausea and vomiting (OR 2.22, 95% CI 1.10–4.46, p < 0.05). Furthermore, the addition of the PARP inhibitor iniparib to gemcitabine and carboplatin treatment improved the rate of clinical benefit, OS and PFS. Conclusions: Platinum-containing chemotherapy remains a highly recommended therapeutic regimen due to greater effectiveness and tolerance for patients with advanced TNBC.

Background: Many breast and ovarian cancer patients have germline or somatic mutations in BRCA 1&2 genes. These proteins are important for repairing double-strand DNA breaks by homologous recombinational repair. In patients who have mutations in these genes, PARP is the major alternative for repairing single-strand DNA breaks. PARP inhibitors (PARPi) inhibit PARP, thereby causing cell death by accumulation of damaged DNA in cells. Many PARPi, including Olaparib, have been approved and used in treatment of metastatic ovarian cancer patients with BRCA 1&2 mutation. Recently, Olaparib was also approved by the FDA for treatment of metastatic breast cancer patients with germline BRCA 1&2 mutation, and many other PARPi are in clinical trial. In this study we analyzed breast cancer patients' awareness, use and experience with PARPi s. Many patients share their experiences on online forums which contain millions of freely shared messages. These can be used to analyze patient concerns and experiences. However, this data is unstructured and difficult to analyze. We used our automated system VoCP, that uses techniques from Big Data Science and Artificial Intelligence (deep learning, topic modeling, information retrieval, and natural language processing) to analyze these messages. Methods: We collected 15.13 million unique messages by 987,189 users from 37 unrestricted cancer forums that provide clinically relevant information. We built custom ontologies for breast cancer, various PARPi, chemotherapy and side effects, and then used our automated system VoCP to extract relevant information from these messages. Results: We found 1,536 breast cancer patients discussing PARPi. 459 patients mentioned use of PARPi whereas 706 patients shared the information about PARPi and 196 inquired about them. 176 patients mentioned that they were planning to use PARPi. 76 patients using PARPi mentioned having BRCA 1 or 2 mutation and 1 patient mentioned CHEK 2 mutation. 91 patients mentioned having triple negative cancer. 212 patients mentioned being treated on clinical trial and 10 mentioned being off trial. 162 patients mentioned use of chemotherapy with PARPi and 40 mentioned use of PARPi as single agent. Specific PARPi: 47 mentioned Olaparib, 104 mentioned Valiparib, & Talazoparib, 6 rucaparib and 4 Niraparib. Most patient just mentioned “PARP inhibitor.” Some patients mentioned iniparib on clinical trial. Side effects were reported by 60 patients. These include: · Nausea: 14 · Fatigue: 15 · GI side effect: 7 · Thrombocytopenia: 5 · Anemia: 2 · Neutropenia: 2 · Neuropathy: 5 · Insomnia:2 99 patients mentioned PARPi were “effective,” 21 mentioned they were “somewhat effective” and 36 mentioned they were “ineffective.” 144 patient expressed positive sentiments, 30 patients expressed negative sentiments and 16 patients expressed neutral sentiment for PARPi. Conclusion: · There is increasing awareness and curiosity for PARPi in breast cancer patients as more patients are being tested for BRCA and other mutations. · Among the users, PARPi are generally associated with low toxicity and positive sentiments. · VoCP reliably provides meaningful insights from the patient's point of view; it also gives insight into unmet needs where more resources and research should be focused. Citation Format: Aggarwal S, Sharma R, Singh M, Aggarwal A. Voice of cancer patient: Analysis of breast cancer patients' experience with PARP inhibitors [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-16-02.

Background: Emerging data suggest that some patients with TNBC could benefit from the addition of immune-based therapy. This observation is in part due to the significant association between distinct tumor-infiltrating lymphocytes (TILs) and prognosis in TNBC. Efforts to comprehensively characterize the immune microenvironment of TNBCs are critically important to gain a better understanding of the immune landscape and how it influences response to both standard chemotherapy and immunotherapy. We previously assessed both stromal TILs (sTILs) and intraepithelial TILs (iTILs) from pre-treatment tumor samples from patients enrolled on a phase II study of neoadjuvant gemcitabine, carboplatin and iniparib (PrECOG 0105; NCT00813956). We found that both iTILS and sTILS significantly associated with pathologic response. Furthermore, we assessed a novel 'in silico flow cytometry' gene expression-based method, CIBERSORT, designed to assess overall immune content and deconvolute the relative levels of distinct leukocyte subsets in tumors. Specific leukocyte subsets significantly associated with pCR included activated memory CD4+ T cells, CD8+ T cells and M1 macrophages (all p Methods: We performed SPARTA - Spatial Perception And Regional Tumor Analysis - a multiplexed immunohistochemistry-based technology with data visualization and analysis modules that is designed to capture clinically relevant information about the tumor microenvironment in 72 pre-treatment FFPE tumor sections from patients enrolled on PrECOG 0105. SPARTA was used to test and analyze the coordinated expression of PD-L1, PD-1, CD45RO, CD4, CD8 and HLA-DRA in the study cohort from whole slide scanned images. Pathologic response at the time of surgery was evaluated using the residual cancer burden index. Germline BRCA1 and BRCA2 status was known for all patients. Results: Of 72 samples, 67 were evaluable for SPARTA analysis. Within a subset of tumors separately profiled by both SPARTA (FFPE/IHC microscopy) and CIBERSORT (Frozen/RNA GEP), we found significant correlation for clinically relevant TIL subpopulations, including for CD8+ T cells (r=0.83, p Conclusions: Spatial mapping of the immune microenvironment in primary TNBC reveals distinct immune cell populations associated with response to neoadjuvant platinum-based therapy. Citation Format: Telli ML, Vinayak S, Khododoust MS, Gruber JJ, Ford JM, Sanchez P, Banayan N, Azimi S, Tumeh PC, Newman AM, Alizadeh AA. Spatial mapping of the immune microenvironment in primary triple-negative breast cancer (TNBC) and association with neoadjuvant therapy response [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD5-12.

Purpose: Iniparib is a purported prodrug causing cell death through intracellular conversion to nitro radical ions. We assessed the efficacy and safety of iniparib with standard radiotherapy and temozolomide in patients with newly diagnosed glioblastoma (GBM). Patients and Methods: Adults meeting eligibility criteria were enrolled in this prospective, single-arm, open-label multi- institution phase II trial with median overall survival (mOS) compared with a historical control as the primary objective. A safety run-in component of radiotherapy + temozolomide + iniparib (n = 5) was followed by an efficacy study (n = 76) with the recommended phase II doses of iniparib (8.0 mg/kg i.v. twice/week with radiotherapy + daily temozolomide followed by 8.6 mg/kg i.v. twice/week with 5/28-day temozolomide). Results: The median age of the 81 evaluable participants was 58 years (63% male). Baseline KPS was ≥ 80% in 87% of participants. The mOS was 22 months [95% confidence interval (CI), 17–24] and the HR was 0.44 (95% CI, 0.35–0.55) per-person-year of follow-up. The 2- and 3-year survival rates were 38% and 25%, respectively. Treatment-related grade 3 adverse events (AEs) occurred in 27% of patients; 9 patients had AEs requiring drug discontinuation including infusion-related reaction, rash, gastritis, increased liver enzymes, and thrombocytopenia. Conclusions: Iniparib is well tolerated with radiotherapy and temozolomide in patients with newly diagnosed GBM at up to 17.2 mg/kg weekly. The primary objective of improved mOS compared with a historical control was met, indicating potential antitumor activity of iniparib in this setting. Dosing optimization (frequency and sequence) is needed prior to additional efficacy studies.

Purpose: In germline BRCA1 or BRCA2 (BRCA1/2) mutation carriers, restoration of tumor BRCA1/2 function by a secondary mutation is recognized as a mechanism of resistance to platinum and PARP inhibitors, primarily in ovarian cancer. We evaluated this mechanism of resistance in newly diagnosed patients with BRCA1/2-mutant breast cancer with poor response to neoadjuvant platinum-based therapy. Experimental Design: PrECOG 0105 was a phase II neoadjuvant study of gemcitabine, carboplatin, and iniparib in patients with stage I–IIIA triple-negative or BRCA1/2 mutation–associated breast cancer (n = 80). All patients underwent comprehensive BRCA1/2 genotyping. For mutation carriers with moderate or extensive residual disease after neoadjuvant therapy, BRCA1/2 status was resequenced in the residual surgical breast tumor tissue. Results: Nineteen patients had a deleterious germline BRCA1/2 mutation, and four had moderate residual disease at surgery. BRCA1/2 sequencing of residual tissue was performed on three patients. These patients had BRCA1 1479delAG, 3374insGA, and W1712X mutations, respectively, with LOH at these loci in the pretreatment tumors. In the first case, a new BRCA1 mutation was detected in the residual disease. This resulted in a 14–amino acid deletion and restoration of the BRCA1 reading frame. A local relapse biopsy 4 months later revealed the identical reversion mutation, and the patient subsequently died from metastatic breast cancer. Conclusions: We report a BRCA1 reversion mutation in a patient newly diagnosed with triple-negative breast cancer that developed over 18 weeks of platinum-based neoadjuvant therapy. This was associated with poor therapy response, early relapse, and death. Clin Cancer Res; 23(13); 3365–70. ©2017 AACR.

Background: TNBC patients with homologous recombination (HR) deficient tumors have significantly higher pathologic complete response (pCR, ypT0/is ypN0) rates when treated with platinum-based chemotherapy. TILs are prognostic and predictive of chemotherapy benefit in TNBC. Interestingly, recent data suggests that HR deficient TNBCs and BRCA1/2 mutant ovarian cancers may be enriched for immune cell infiltration. Thus, we performed a pooled analysis of 5 phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to evaluate the association of TILs with HR deficiency status and tumor BRCA1/2 mutation status. Methods: 166 patients with TNBC and known HR deficiency status from the following clinical trials were available for analysis: PrECOG 0105 (N=72), NCT00580333 (N=32), NCT01372579 (N=26), TBCRC 008 (N=18) and NCT00148694 (N=18). Neoadjuvant chemotherapy regimens included 1) carboplatin, gemcitabine, iniparib, 2) cisplatin with or without bevacizumab 3) carboplatin, eribulin, 4) carboplatin, nab-paclitaxel, with or without vorinostat. HR deficiency status was defined as a high HRD score (42 or higher) and/or presence of a BRCA1/2 tumor mutation (tBRCA). Digitized pre-treatment core biopsy H&E sections were reviewed and scored by two blinded expert breast cancer pathologists using the international TIL working group guidelines. The density (%) of both intratumoral TILs (iTILs) and stromal TILs (sTILs) was recorded by deciles (n=122 thus far, additional cases to be included in final analysis). Results: Among 122 patients, pCR was achieved in 36 patients (29.5%) and 71 tumors (58.2%) were HR deficient. In total, 24 patients (19.7%) patients had a deleterious BRCA1/2 mutation. Among all tumors, iTIL and sTIL median densities were 0% (range 0-20) and 10% (range 0-80), respectively, and were not statistically different in HR deficient versus non-deficient tumors (iTIL p=0.746; sTIL p=0.159). The same absent association was observed for tBRCA mutation status (iTIL p=0.607; sTIL p=0.315) and binary HRD score (iTIL p=0.879; sTIL p=0.364). Updated results with additional cases scored for TILs will be reported at time of presentation. Additional analyses assessing the relationship between TILs and pCR/residual cancer burden adjusting for HRD status and other clinical variables will also be included at the time of presentation. Conclusion: Several previous studies have reported that TILs are significantly associated with response to standard chemotherapy regimens when given in the neoadjuvant setting. Measures of genomic instability and DNA repair deficiency, including HRD, have been shown to be robust predictors of response to chemotherapy, including platinum containing regimens. It is unclear if TILs will be predictive in a similarly robust way for response to platinum-containing regimens. Results of this study suggest TIL density and HR deficiency status may be independent and non-overlapping. Final analysis including additional cases will be included in the final presentation.Background: TNBC patients with homologous recombination (HR) deficient tumors have significantly higher pathologic complete response (pCR, ypT0/is ypN0) rates when treated with platinum-based chemotherapy. TILs are prognostic and predictive of chemotherapy benefit in TNBC. Interestingly, recent data suggests that HR deficient TNBCs and BRCA1/2 mutant ovarian cancers may be enriched for immune cell infiltration. Thus, we performed a pooled analysis of 5 phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to evaluate the association of TILs with HR deficiency status and tumor BRCA1/2 mutation status. Methods: 166 patients with TNBC and known HR deficiency status from the following clinical trials were available for analysis: PrECOG 0105 (N=72), NCT00580333 (N=32), NCT01372579 (N=26), TBCRC 008 (N=18) and NCT00148694 (N=18). Neoadjuvant chemotherapy regimens included 1) carboplatin, gemcitabine, iniparib, 2) cisplatin with or without bevacizumab 3) carboplatin, eribulin, 4) carboplatin, nab-paclitaxel, with or without vorinostat. HR deficiency status was defined as a high HRD score (42 or higher) and/or presence of a BRCA1/2 tumor mutation (tBRCA). Digitized pre-treatment core biopsy H&E sections were reviewed and scored by two blinded expert breast cancer pathologists using the international TIL working group guidelines. The density (%) of both intratumoral TILs (iTILs) and stromal TILs (sTILs) was recorded by deciles (n=122 thus far, additional cases to be included in final analysis). Results: Among 122 patients, pCR was achieved in 36 patients (29.5%) and 71 tumors (58.2%) were HR deficient. In total, 24 patients (19.7%) patients had a deleterious BRCA1/2 mutation. Among all tumors, iTIL and sTIL median densities were 0% (range 0-20) and 10% (range 0-80), respectively, and were not statistically different in HR deficient versus non-deficient tumors (iTIL p=0.746; sTIL p=0.159). The same absent association was observed for tBRCA mutation status (iTIL p=0.607; sTIL p=0.315) and binary HRD score (iTIL p=0.879; sTIL p=0.364). Updated results with additional cases scored for TILs will be reported at time of presentation. Additional analyses assessing the relationship between TILs and pCR/residual cancer burden adjusting for HRD status and other clinical variables will also be included at the time of presentation. Conclusion: Several previous studies have reported that TILs are significantly associated with response to standard chemotherapy regimens when given in the neoadjuvant setting. Measures of genomic instability and DNA repair deficiency, including HRD, have been shown to be robust predictors of response to chemotherapy, including platinum containing regimens. It is unclear if TILs will be predictive in a similarly robust way for response to platinum-containing regimens. Results of this study suggest TIL density and HR deficiency status may be independent and non-overlapping. Final analysis including additional cases will be included in the final presentation. Citation Format: Telli ML, Badve S, Vinayak S, Silver DP, Isakoff SJ, Kaklamani VG, Gradishar WJ, Stearns V, Connolly RM, Ford JM, Adams S, Garber JE, Evans B, Timms K, Wenstrup R, Richardson AL. Evaluation of tumor infiltrating lymphocytes (TILs) and their association with homologous recombination deficiency and BRCA1/2 mutation status in triple-negative breast cancer (TNBC): A pooled analysis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-09.

Dogs develop cancer spontaneously with age, with breed-specific risk underlying differences in genetics. Mammary tumors are reported as the most frequent neoplasia in intact female dogs. Their high prevalence in certain breeds suggests a genetic component, as it is the case in human familial breast cancer, distinctly in BRCA2-associated cancers. However, the molecular genetics of BRCA2 in the pathogenesis of canine cancer are still under investigation.Genetic variations of canine BRCA2 comprised single nucleotide polymorphisms, insertions and deletions. The BRCA2 level has been shown to be reduced in tumor gland samples, suggesting that low expression of BRCA2 is contributing to mammary tumor development in dogs. Additionally, specific variations of the BRCA2 gene affect RAD51 binding strength, critically damage the BRCA2-RAD51 binding and further provoke a defective repair. In humans, preclinical and clinical data revealed a synthetic lethality interaction between BRCA2 mutations and PARP inhibition. PARP inhibitors are successfully used to increase chemo- and radiotherapy sensitivity, although they are also associated with numerous side effects and acquired resistance. Cancer treatment of canine patients could benefit from increased chemo- and radiosensitivity, as their cancer therapy protocols usually include only low doses of drugs or radiation. Early investigations show tolerability of iniparib in dogs. PARP inhibitors also imply higher therapy costs and consequently are less likely to be accepted by pet owners.We summarized the current evidence of canine BRCA2 gene alterations and their association with mammary tumors. Mutations in the canine BRCA2 gene have the potential to be exploited in clinical therapy through the usage of PARP inhibitors. However, further investigations are needed before introducing PARP inhibitors in veterinary clinical practice.

Background: TNBC patients with homologous recombination (HR) deficient tumors have significantly higher pathologic complete response (pCR, ypT0/is ypN0) rates when treated with platinum-based chemotherapy regimens than TNBC patients whose tumors are HR non-deficient. We performed a pooled analysis of 5 phase II studies that included patients with TNBC treated with neoadjuvant platinum-based chemotherapy to better estimate the pCR rates amongst HR deficient and HR non-deficient tumors. Methods: Patients with TNBC and known HR deficiency status from the following clinical trials were available for analysis: PrECOG 0105 (N=72), NCT00148694/NCT00580333 (N=50), NCT01372579 (N=26), TBCRC 008 (N=18). Neoadjuvant chemotherapy regimens included 1) carboplatin, gemcitabine, iniparib, 2) cisplatin with or without bevacizumab 3) carboplatin, eribulin, 4) carboplatin, nab-paclitaxel, with or without vorinostat. HR deficiency status was defined as a high HRD score (42 or higher) and/or presence of a BRCA1/2 tumor mutation (tBRCA). Logistic regression models were used to adjust for study effects. The addition of data from the TNBC platinum-treated arm of GeparSixto (n=101) to this pooled analysis will be available at the time of presentation bringing the total sample size to 267. Results: pCR was achieved in 51 patients (31%) and 104 patients (63%) were HR deficient (31 with high HRD score and tBRCA mutation, 67 with high HRD score only, and 6 with tBRCA mutation only). Patients with HR deficient tumors were more likely to achieve a pCR than those with HR non-deficient tumors: 44% vs. 8% (p Likelihood of pCR adjusting for studyModel #Predictor VariablePopulation (n)Adjusted Odds RatioLower 95% CIUpper 95% CIP Value1HR DeficiancyAll (166)12.54.237.3 Conclusion: HR deficiency status is a robust predictor of pCR across different neoadjuvant platinum-based regimens. This pooled analysis suggests that HRD can be used to identify TNBC patients with a high probability of obtaining pCR with a platinum-based neoadjuvant chemotherapy regimen. Citation Format: Telli ML, McMillan A, Ford JM, Richardson AL, Silver DP, Isakoff SJ, Kaklamani VG, Gradishar W, Stearns V, Connolly RM, Loibl S, Elkin EP, Timms K, Hartman A-R, von Minckwitz G. Homologous recombination deficiency (HRD) as a predictive biomarker of response to neoadjuvant platinum-based therapy in patients with triple negative breast cancer (TNBC): A pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-12.

Metastatic triple-negative breast cancer (TNBC) is a phenotypic breast cancer subgroup with a very poor prognosis, despite standard treatments. Combined twice-weekly iniparib and gemcitabine/carboplatin (GC+tw-iniparib) showed benefit over gemcitabine/carboplatin in a randomized phase II trial, and a phase III was initiated comparing these regimens. The present phase II study was initiated to compare GC+tw-iniparib with a more practical once-weekly schedule (GC+w-iniparib) in TNBC. Metastatic TNBC patients were randomized to receive iniparib weekly (11.2 mg/kg on days 1 and 8) or twice-weekly (5.6 mg/kg on days 1, 4, 8, and 11) with gemcitabine (1000 mg/m2) and carboplatin (area under the curve 2 on days 1 and 8), every 3 weeks. The primary endpoint was the overall response rate (ORR). Pharmacokinetics of iniparib and its two metabolites were analyzed. A total of 163 patients were randomized, 82 GC+w-iniparib and 81 GC+tw-iniparib. Demographic and baseline characteristics were well balanced. ORR was 34.1% (95% CI 23.9–44.4%) vs. 29.6% (95% CI 19.7–39.6%) and median progression-free survival was 5.5 months (95% CI 4.2–5.7) vs. 4.3 months (95% CI 3.0–5.8) for GC+w-iniparib and GC+tw-iniparib, respectively. Safety was similar across treatment arms in terms of event severity and type. Iniparib plasma concentrations and exposure were two-fold higher with w-iniparib compared to tw-iniparib. Iniparib and its metabolites were cleared rapidly with a terminal half-life of

Triple‐negative breast cancer (TNBC) is a heterogeneous disease with poorer prognosis than other subtypes, yet effective therapies are still not available. We aimed to compare the efficacy of various targeted therapies with chemotherapy (CT) in TNBC patients using a network meta‐analysis. A systematic literature search was performed in PubMed, EMBASE, and the Cochrane Library. A total of 27 randomized controlled trials (RCTs), involving 6924 TNBC patients, were included. Olaparib significantly improved PFS (0.43, 0.29‐0.64) and ORR (2.57, 1.31‐5.09) in comparison with CT. As for bevacizumab + CT, it showed a significant improvement of PFS (0.66, 0.55‐0.80) and ORR (2.15, 1.16‐4.05) compared with CT + placebo. It was also superior to CT alone in PFS (0.48, 0.35‐0.65) and pCR (1.30, 1.13‐1.49 for breast and axillary nodes and 1.26, 1.11‐1.44 for breast). Other targeted agents like iniparib, sorafenib, cetuximab, and ipatasertib combined with CT showed significant superiority in PFS compared with CT alone, and the HRs were 0.75 (0.62‐0.90), 0.44 (0.21‐0.91), 0.67 (0.47‐0.96), and 0.44 (0.24‐0.81), respectively, while some other agents such as sunitinib and cetuximab had the lowest SUCRA in OS, PFS, or ORR without any benefits. In conclusion, our results indicated that the addition of bevacizumab to CT was beneficial for TNBC patients, and olaparib had a great effect in PFS and ORR, especially for those with BRCA mutations. When combined with CT, targeted agents including iniparib, sorafenib, cetuximab, and ipatasertib may have better efficacies for treating TNBC.

Iniparib is a prodrug that converts to highly reactive cytotoxic metabolites intracellularly with activity in preclinical glioma models. We investigated the maximum tolerated dose (MTD) of iniparib with monthly (m) and continuous (c) temozolomide (TMZ) dosing schedules in patients with malignant gliomas (MG). Adults with newly diagnosed MG who had successfully completed ≥80% of radiation (RT) and TMZ without toxicity received mTMZ dosing (150-200 mg/m(2) days 1-5/28 days) or cTMZ dosing (75 mg/m(2)/days × 6 weeks) in conjunction with iniparib (i.v. 2 days/week) in the adjuvant setting. Iniparib was dose escalated using a modified continual reassessment method (mCRM). 43 patients (32 male; 34 GBM, 8 AA, 1 gliosarcoma; median age 54 years; median KPS 90) were enrolled across 4 dose levels. In the mTMZ group, 2/4 patients had dose limiting toxicities (DLT) at 19 mg/kg/week (rash/hypersensitivity). At 17.2 mg/kg/week, 1/9 patients had a DLT (grade 3 fatigue). Additional grade 3 toxicities were neutropenia, lymphopenia, and nausea. In the cTMZ group, one DLT (thromboembolic event) occurred at 10.2 mg/kg/week. Dose escalation stopped at 16 mg/kg/week based on mCRM. The mean maximum plasma concentration of iniparib increased with dose. Concentration of the two major circulating metabolites, 4-iodo-3-aminobenzamide and 4-iodo-3-aminobenzoic acid, was ≤5% of the corresponding iniparib concentration. Iniparib is well tolerated, at doses higher than previously investigated, in combination with TMZ after completion of RT + TMZ in patients with MG. Recommended phase 2 dosing of iniparib based on mCRM is 17.2 mg/kg/week with mTMZ and 16 mg/kg/week with cTMZ. An efficacy study of TMZ/RT + iniparib followed by TMZ + iniparib in newly diagnosed GBM using these doses has completed enrollment. Survival assessment is ongoing.

Purpose This study was designed to assess efficacy, safety, and predictors of response to iniparib in combination with gemcitabine and carboplatin in early-stage triple-negative and BRCA1/2 mutation–associated breast cancer. Patients and Methods This single-arm phase II study enrolled patients with stage I to IIIA (T ≥ 1 cm) estrogen receptor–negative (≤ 5%), progesterone receptor–negative (≤ 5%), and human epidermal growth factor receptor 2–negative or BRCA1/2 mutation–associated breast cancer. Neoadjuvant gemcitabine (1,000 mg/m2 intravenously [IV] on days 1 and 8), carboplatin (area under curve of 2 IV on days 1 and 8), and iniparib (5.6 mg/kg IV on days 1, 4, 8, and 11) were administered every 21 days for four cycles, until the protocol was amended to six cycles. The primary end point was pathologic complete response (no invasive carcinoma in breast or axilla). All patients underwent comprehensive BRCA1/2 genotyping, and homologous recombination deficiency was assessed by loss of heterozygosity (HRD-LOH) in pretreatment core breast biopsies. Results Among 80 patients, median age was 48 years; 19 patients (24%) had germline BRCA1 or BRCA2 mutations; clinical stage was I (13%), IIA (36%), IIB (36%), and IIIA (15%). Overall pathologic complete response rate in the intent-to-treat population (n = 80) was 36% (90% CI, 27 to 46). Mean HRD-LOH scores were higher in responders compared with nonresponders (P = .02) and remained significant when BRCA1/2 germline mutations carriers were excluded (P = .021). Conclusion Preoperative combination of gemcitabine, carboplatin, and iniparib is active in the treatment of early-stage triple-negative and BRCA1/2 mutation–associated breast cancer. The HRD-LOH assay was able to identify patients with sporadic triple-negative breast cancer lacking a BRCA1/2 mutation, but with an elevated HRD-LOH score, who achieved a favorable pathologic response. Confirmatory controlled trials are warranted.

PARP inhibitors are considered promising anti-cancer agents and currently being tested in clinical trials in hereditary breast cancer patients harboring mutations in BRCA1 and BRCA2 genes. In this study, we investigated the antiproliferative effects and mechanism of PARP inhibitors ABT-888 (Veliparib), BSI-201 (Iniparib) and AZD228 (Olaparib) in breast cancer cell lines with BRCA1 or BRCA2 mutations and 9 different BRCA wild-type cell lines with BRCA1 allelic loss. We found that AZD2281 was the most potent in the PARP inhibitors and induces significant growth inhibition (~95%) in BRCA1 mutant (HCC-1937, MDA-MB-436, and SUM-149PT) and BRCA2 mutant (HCC-1428) cell lines. AZD2281 treatment also resulted in growth inhibition ranging from 20 to 50% in cells with BRCA1 allelic loss, including ER(+), HER2/Neu(+) and triple-negative breast cancer (TNBC) cells, but showed no effect in cells without with type BRCA without allelic loss. Knocking down of BRCA1 or BRCA2 in TNBC cells with BRCA1 allelic loss by RNA interference significantly enhanced AZD2281-induced growth inhibition and induced significant autophagy that was associated with mitophagy in cells with BRCA mutations. Inhibition of autophagy by gene knockdown significantly diminished AZD2281-induced mitophagy and apoptosis, indicating that autophagic process mediates some of the downstream effects of PARP inhibitors. In conclusion, our data provide the first evidence of PARP inhibitor AZD2281 autophagy and mitophagy in breast cancer cell lines with BRCA mutations or BRCA-allelic loss. In addition, our results indicate that the patients with BRCA1 allelic loss may also benefit from PARP inhibitor therapy if BRCA is further inhibited.

The development of drug-biomarker combinations holds promise for tailoring treatment for patients with cancer on the basis of the biology of the tumor exemplified by estrogen receptor expression and blockade and human epidermal growth factor receptor 2 targeting. Approximately 85% of breast cancers have a target for therapy, but triple-negative breast cancers (TNBCs) do not. Although trials have focused on identifying the most efficacious anticancer drug (regimen) for this subtype, it may be that predictive biomarkers are required to guide treatment choices because of the intrinsic heterogeneity of TNBCs. Molecular characterizations have demonstrated a strong association between TNBCs and BRCA1 mutations. Preclinical mechanistic insight indicated that tumor cells with a defect in BRCA1 have impaired homologous recombination (HR), the only error-free pathway of repair of interstrand crosslinks. Cells with impaired HR display sensitivity to agents that induce such lesions. In the general breast cancer population, platinum agents that cause interstrand crosslinks are not preferred over other treatment regimens. However, given the possibility that TNBCs are enriched for such a targetable HR deficiency (HRD), platinum has attracted renewed interest as has been shown in recently published articles. Furthermore, TNBCs may be enriched for BRCA1 mutations and also for a larger group of nonmutated tumors that exhibit HRD. The use of platinum in TNBCs with biomarker analyses has been investigated in the two articles that accompany this editorial. Telli et al neoadjuvantly treated patients with triple-negative or BRCA1/ 2-associated breast cancer with a regimen containing gemcitabine, carboplatin, and iniparib in the PrECOG 0105 trial. Overall, a pathologic complete remission rate of 36% and acceptable toxicity of the regimen were reported. Isakoff et al conducted a phase II trial with cisplatin or carboplatin in patients with metastatic TNBC (TBCRC009; Platinum for Triple-Negative Metastatic Breast Cancer and Evaluation of p63/p73 as a Biomarker of Response). The overall response rate was 25%. Both studies reproduce previous findings of efficacy of a platinum-based regimen or platinum alone in TNBC. However, only a subset of patients in these trials derived clinical benefit. Therefore, secondary investigations may help identify biomarkers that associate with a preferential benefit from use of a platinum regimen, which may help guide therapy decisions. Both studies report their analysis of BRCA germline mutation status as well as potential biomarkers for assessing HRD, specifically the HRD loss of heterozygosity (HRD-LOH) score and the HRD large-scale transition (HRD-LST) score. Both markers evaluate so-called genomic scars as signatures of aberrations that can be observed from singlenucleotide polymorphism array–based sequencing or similar technologies and that are associated with defects in error-free repair of interstrand crosslinks. The HRD-LOH score counts the numbers of LOH regions larger than 15 MB but smaller than chromosome size, whereas the HRD-LST score counts the number of breaks between adjacent segments of at least 10 MB. Cutoffs were trained to best separate tumors that had a known deleterious aberration in BRCA1/2 from those that did not. In both studies, patients with a BRCA germline mutation had higher response rates than the general cohort, and the HRD scores highly correlated with BRCA1/2 germline mutations and response rates. In addition, Telli et al identified BRCA1 methylation in nonmutated tumors with high HRD-LOH score, which suggests that these scores identify a subgroup of patients who could benefit from therapy that targets their HRD. Unfortunately, single-arm phase II studies do not allow proper evaluation of a biomarker as a predictor of response to therapy, and they offer limited insight on how to exploit the observed association with outcome of BRCA-associated biomarkers (Fig 1). Thus, the studies by Telli et al and Isakoff et al join several other articles published over the last decade that have reported on the potential promise of BRCA-associated HRD biomarkers but did not provide definitive data on clinical utility. It has been established that the optimal biomarker trial design requires biomarker-positive and -negative patients and patients who have been treated with and without the therapy of interest to evaluate both prognostic and predictive signals. If not included in the phase II design, such a control group could be added. Hence, the lack of a control arm in these two new studies is indeed a major limitation of their findings. In contrast, the TNT trial (Triple Negative Breast Cancer Trial, recently reported as an abstract) was able to more appropriately evaluate the use of HRD biomarkers, at least in patients with advanced disease. In that trial, patients with locally advanced or metastatic TNBC were randomly assigned to therapy with carboplatin at area under the [concentration-time] curve 6 or standardof-care docetaxel. Of great interest, among the 376 patients in that study, 29 were known to be BRCA1 or BRCA2 mutation carriers (including 13 who had estrogen receptor–positive, HER2-negative disease). Prespecified analyses specifically addressed populations JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 33 NUMBER 17 JUNE 1

INTRODUCTION Among breast cancers, the triple negative subtype (negative for hormone receptors and not overexpressing HER2) has the worst prognosis and its response to Iniparib has been investigated in clinical trials. Further investigations are needed to optimize drug schedule and patient selection criteria. Iniparib antitumor mechanism is not completely understood, as well as iniparib diffusion kinetic into tumoral tissues. We address these questions in spontaneous canine invasive mammary carcinomas, which are a good model for this cancer subtype (Ibisch et al., World Veterinary Cancer Congress 2012), in a neoadjuvant setting. To our knowledge, this is the first study of iniparib administration in cancer-bearing dogs. MATERIAL AND METHODS Twenty female dogs with spontaneous MT with malignant criteria (tumor size, speed of growth, ulceration, relapse, or metastasis) were included. All tumors were described as rapidly growing. Dogs received a first infusion of iniparib at day 0 and a combination of carboplatin and iniparib at day 7. Biological materials (tumor biopsies and blood) were collected before and 5 minutes after iniparib infusion for pharmacokinetic and metabolism studies. Tumor response was evaluated by caliper measurements and histopathological analysis of mammary tumors and draining lymph nodes. A chain mastectomy was performed 3 or 4 weeks later. Histological records included the subtype of carcinoma (WHO 1999), Elston & Ellis grade, presence of emboli, lymph node metastasis and IHC stainings using ER, PR, Her2 (scored according to Wolff et al.2007), CK5/6, EGF-R and Ki67. Intensity of necrosis and apoptosis was evaluated using PAS coloration and immunohistochemistry for caspase 3, at DO on tumor biopsies and at surgery. Toxicity of the protocol was evaluated and its efficiency on invasive carcinomas was compared to surgery alone (control group of 27 female dogs with invasive mammary carcinomas treated by chain mastectomy alone). RESULTS Treated and control groups shared similar features concerning animal breeds, age, neutering status and tumor location. 75% of the treated MT were malignant. Necrosis and apoptosis were significantly increased in respectively 63 and 56% of iniparib treated tumors. Clinical evidence of toxicity was minimal (15% of dogs with nausea, 60% with transient polyuria-polydipsia). Tumor stabilization was observed before surgery in all dogs but one. Median survival has not been reached. CONCLUSION Iniparib at 35mg/kg combined with carboplatin at 300 mg/m2 seemed well tolerated in this study and deserves further investigations. The degree of necrosis and apoptosis in the treated tumors can be evaluated with these techniques. Iniparib pharmacokinetic and metabolism studies in cancer-bearing dogs are ongoing. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-05-08.

PARP inhibitors, both as monotherapy and in combination with cytotoxic drugs, are currently undergoing clinical trials in several different cancer types. In this investigation, we compared the antiproliferative activity of two PARP/putative PARP inhibitors, i.e., olaparib and iniparib, in a panel of 14 breast cancer cell lines (seven tripe-negative and seven non-triple-negative). In almost all cell lines investigated, olaparib was a more potent inhibitor of cell growth than iniparib. Inhibition by both drugs was cell line-dependent and independent of the molecular subtype status of the cells, i.e., whether cells were triple-negative or non-triple negative. Although the primary target of PARP inhibitors is PARP1, no significant association was found between baseline levels of PARP1 activity and inhibition with either agent. Similarly, no significant correlation was evident between sensitivity and levels of CDK1, BRCA1 or miR-182. Combined addition of olaparib and either the CDK1 inhibitor, RO-3306 or a pan HER inhibitor (neratinib, afatinib) resulted in superior growth inhibition to that obtained with olaparib alone. We conclude that olaparib, in contrast to iniparib, is a strong inhibitor of breast cancer cell growth and may have efficacy in breast cancer irrespective of its molecular subtype, i.e., whether HER2-positive, estrogen receptor (ER)-positive or triple-negative. Olaparib, in combination with a selective CDK1 inhibitor or a pan HER inhibitor, is a potential new approach for treating breast cancer.

Ovarian cancer (OC) carries a poor prognosis; however, accumulating molecular data for the major histologic subtypes may lead to subtype-specific treatment paradigms. The present review discusses what is currently understood about the major molecular and histologic subgroups of OC. Areas specifically addressed include hormonal pathways, tumor protein p53 (TP53) and AT rich interactive domain 1A (SWI-like; ARID1A) mutation, and the breast cancer 1/2, early onset (BRCA1/2) mutation/poly (ADP-ribose) polymerase 1 (PARP1), phosphatidylinositol-4,5-bisphosphate 3- kinase, catalytic subunit alpha (PI3KCA)/v-akt murine thymoma viral oncogene homolog 1 (AKT1)/mechanistic target of rapamycin (MTOR), and mitogen-activated protein kinase kinase 1 and 2 (MAP2K1/2) pathways. This molecular characterization only very recently has impacted clinical research efforts to develop targeted therapies for both common and rare OC subtypes. This targeted strategy is illustrated by ongoing low-grade serous, clear-cell, and mucinous subtypeexclusive clinical trials evaluating agents based on common molecular abnormalities among patients (i.e., PARP1 inhibitors for BRCA1/2 mutation-positive OC). This report also reviews the published clinical trial efficacy data for investigational therapies within specific subgroups, and summarizes the currently active clinical trials evaluating these agents (e.g., temsirolimus, sunitinib, TP53 immunotherapy, olaparib, iniparib, veliparib). Available data suggest that histologic profiles and molecular tumor markers are valuable resources for identifying patients who may benefit from these specific agents, and future research should focus on targeting molecules and signaling pathways that are most commonly altered in each subtype.

Women with triple negative breast cancer (TNBC) have poor prognosis compared to other breast cancer subtypes. There were several reports indicating racial disparity in breast cancer outcomes between African American (AA) and European American (EA) women. For example, the mortality rates of AA breast cancer patients were three times higher than of EA patients, even though, the incidence is lower in AA women. Our in vitro studies indicate that cancer stem-like cells (CSCs) derived from AA TNBC cell lines have significantly higher self-renewal potential (mammosphere formation) than CSCs derived from EA cell lines. TNBC tumors express high levels of Myc compared to luminal A or HER2 expressing breast cancers. We studied the effects of c-Myc overexpression on CSCs and chemotherapy in AA, and EA derived TNBC cell line(s). Overexpression of c-Myc in AA derived MDA-MB-468 (Myc/MDA-468) cells resulted in a significant increase in CSCs and with minimal changes in epithelial-to-mesenchymal transition (EMT) compared to the control group. In contrast, overexpression of c-Myc in EA derived MDA-MB-231(Myc/MDA-231) cells led to increased epithelial-to-mesenchymal transition (EMT), with a minimal increase in CSCs compared to the control group. Myc/MDA-468 cells were resistant to standard chemotherapeutic treatments such as iniparib (PARP inhibitor) plus cisplatin, / iniparib, cisplatin, paclitaxel and docetaxel. However, Myc/MDA-231 cells, which showed EMT changes responded to iniparib with cisplatin, but were resistant to other drugs, such as iniparib, cisplatin, paclitaxel and docetaxel. Collectively, our results indicate that intrinsic differences in the tumor biology may contribute to the breast cancer disparities.

Purpose: BRCA1/2-mutated and some sporadic triple-negative breast cancers (TNBC) have DNA repair defects and are sensitive to DNA-damaging therapeutics. Recently, three independent DNA-based measures of genomic instability were developed on the basis of loss of heterozygosity (LOH), telomeric allelic imbalance (TAI), and large-scale state transitions (LST). Experimental Design: We assessed a combined homologous recombination deficiency (HRD) score, an unweighted sum of LOH, TAI, and LST scores, in three neoadjuvant TNBC trials of platinum-containing therapy. We then tested the association of HR deficiency, defined as HRD score ≥42 or BRCA1/2 mutation, with response to platinum-based therapy. Results: In a trial of neoadjuvant platinum, gemcitabine, and iniparib, HR deficiency predicted residual cancer burden score of 0 or I (RCB 0/I) and pathologic complete response (pCR; OR = 4.96, P = 0.0036; OR = 6.52, P = 0.0058). HR deficiency remained a significant predictor of RCB 0/I when adjusted for clinical variables (OR = 5.86, P = 0.012). In two other trials of neoadjuvant cisplatin therapy, HR deficiency predicted RCB 0/I and pCR (OR = 10.18, P = 0.0011; OR = 17.00, P = 0.0066). In a multivariable model of RCB 0/I, HR deficiency retained significance when clinical variables were included (OR = 12.08, P = 0.0017). When restricted to BRCA1/2 nonmutated tumors, response was higher in patients with high HRD scores: RCB 0/I P = 0.062, pCR P = 0.063 in the neoadjuvant platinum, gemcitabine, and iniparib trial; RCB 0/I P = 0.0039, pCR P = 0.018 in the neoadjuvant cisplatin trials. Conclusions: HR deficiency identifies TNBC tumors, including BRCA1/2 nonmutated tumors more likely to respond to platinum-containing therapy. Clin Cancer Res; 22(15); 3764–73. ©2016 AACR.

Poly(ADP-ribose) polymerase (PARP) family has become a promising therapeutic target in various malignancies including breast cancer. When homologous recombination repair is deficient, as it is observed in BRCA1/2-mutated tumor models, inhibition of PARP was shown to induce massive and selective tumor cell death (the so-called "synthetic lethality"). In breast cancer, PARP inhibitors have been developed as single-agent in BRCA1/2-mutated tumors or in combination with chemotherapy. Recently, a randomized phase III clinical trial failed to demonstrate any survival improvement by combining the iPARP iniparib to chemotherapy in triple-negative metastatic breast cancer patients. This emphasizes the need for future development of this class of compounds to resolve critical issues such as optimal schedule of administration and association to other anticancer treatments, as well as identification of pertinent biomarkers predictive for efficacy.

Purpose: PARP inhibitors are being developed as therapeutic agents for cancer. More than six compounds have entered clinical trials. The majority of these compounds are β-nicotinamide adenine dinucleotide (NAD+)-competitive inhibitors. One exception is iniparib, which has been proposed to be a noncompetitive PARP inhibitor. In this study, we compare the biologic activities of two different structural classes of NAD+-competitive compounds with iniparib and its C-nitroso metabolite. Experimental Design: Two chemical series of NAD+-competitive PARP inhibitors, iniparib and its C-nitroso metabolite, were analyzed in enzymatic and cellular assays. Viability assays were carried out in MDA-MB-436 (BRCA1-deficient) and DLD1−/− (BRCA2-deficient) cells together with BRCA-proficient MDA-MB-231 and DLD1+/+ cells. Capan-1 and B16F10 xenograft models were used to compare iniparib and veliparib in vivo. Mass spectrometry and the 3H-labeling method were used to monitor the covalent modification of proteins. Results: All NAD+-competitive inhibitors show robust activity in a PARP cellular assay, strongly potentiate the activity of temozolomide, and elicit robust cell killing in BRCA-deficient tumor cells in vitro and in vivo. Cell killing was associated with an induction of DNA damage. In contrast, neither iniparib nor its C-nitroso metabolite inhibited PARP enzymatic or cellular activity, potentiated temozolomide, or showed activity in a BRCA-deficient setting. We find that the nitroso metabolite of iniparib forms adducts with many cysteine-containing proteins. Furthermore, both iniparib and its nitroso metabolite form protein adducts nonspecifically in tumor cells. Conclusions: Iniparib nonselectively modifies cysteine-containing proteins in tumor cells, and the primary mechanism of action for iniparib is likely not via inhibition of PARP activity. Clin Cancer Res; 18(2); 510–23. ©2011 AACR.

Rationale: It was hypothesised that Iniparib or 4-iodo-3-nitrobenzamide acts as an irreversible inhibitor of PARP1 and possibly other enzymes. It has shown successively promising then confusing results in MTNBC in combination with chemotherapy. To date, its mechanism of action has not been completely elucidated but since 1992, inhibition of glycolysis by iniparib and subsequent necrotic cell death has been described. We hypothesised that early inhibition of glycolysis evidenced by in-vivo imaging with 2-((18)F)Fluoro-2-Deoxy-D-Glucose Positron-Emission Tomography (18FDG-PET) may be a predictor of efficacy to iniparib, as it was previously reported for other anticancer drugs. Objectives: To detect metabolic pharmacodynamic effect of iniparib plus chemotherapy by means of 18FDG PET and proof the concept of its use as an early predicitive tool of Iniparib efficacy in MTNBC. Patients & Methods: From March to November 2011, 8 pts were included in our institution in a randomized phase II study comparing bi-weekly versus weekly iniparib treatement in combination with gemcitanine and carboplatin. All patients had 18FDG-PET at baseline, at day 7 (D7). The maximum value of standardized uptake value (SUVmax) of all measurable metastatic lesions was measured and the median SUVmax was calculated for all patients at baseline and D7. The metabolic response was defined as the percentage of reduction of SUVmax (SUVmax Baseline — SUVmax D7) / SUVmax Baseline and the median SUVmax response was correlated to RECIST 1.1 response at six weeks and to disease-free survival (DFS). Results: The median decrease in SUVmax of evaluable lesions measured at D7 was predictive of RECIST 1.1 response at six weeks and was correlated to the best obtained response during the treatment phase. Furthermore, it showed a linear correlation with DFS (y = −0,0007x - 0,1325; R2 = 0,3402). Conclusion: Metabolic pharmacodynamic effect as evidenced by 18FDG PET as soon as one week of treatement act as an early predicitive tool of Iniparib plus chemotherapy efficacy in MTNBC. Considering the lack of a predicitive biomarker of response and if confirmed on larger study, 18FDG PET could be used as a surrogate predictive biomarker is this setting. These results may be considered as an in-vivo proof of concept for the inhibition of glycolysis by iniparib. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-10-01.

Background Iniparib (BSI-201) is an investigational anticancer agent whose precise mechanism of action is under active investigation. In breast cancer cell lines and xenograft models of triple-negative breast cancer (TNBC), iniparib exhibits anti-proliferative activity and potentiates the cell cycle effects of some DNA damaging agents. In a randomized, open-label phase 2 study in pts with metastatic TNBC (mTNBC), iniparib combined with gemcitabine (G) and carboplatin (C) (GC) improved efficacy outcomes compared with GC alone. A confirmatory phase 3 study with GCI failed to meet pre-specified criteria for PFS and OS; however, an exploratory subset analysis demonstrated a potential benefit amongst 2nd/3rd line pts (O'Shaughnessy et al. ASCO 2011). Here we report results of a randomized phase 2 study (NCT01045304) in pts with mTNBC, which assesses efficacy and pharmacokinetics (PK) of iniparib administered either biw or qw in combination with GC. Patients and methods: Eligible pts (N=163; median age 49 yrs) had documented and measurable TNBC, ECOG PS 0–1, normal organ/marrow function, and had received ≤2 prior chemotherapy (CT) regimens for metastatic disease. Pts were randomized (1:1) to receive G (1,000 mg/m2, IV, d 1, 8) plus C (AUC 2, IV, d 1, 8) and iniparib either biw (5.6 mg/kg, IV d 1,4,8,11) or qw (11.2 mg/kg, IV d 1,8) on a 21 d cycle. Pts were stratified according to prior CT for mTNBC (0 vs. 1–2). The primary efficacy endpoint was overall response rate (ORR; CR + PR); secondary endpoints included: clinical benefit rate (CBR; CR + PR + SD for 24 weeks), PFS, OS and PK. Results: At the time of analysis, 23% of patients were still on treatment. The median number of cycles administered per patient was 6 in both arms; exposure to iniparib was identical. Safety data are not fully validated. All pts experienced at least 1 treatment emergent adverse event (TEAE). Grade (Gr) ≥3 TEAEs occurred in 94% and 85% of pts in the biw and qw arms, respectively. TEAEs Gr ≥3 occurring in ≥5% of pts regardless of relationship to study drug (biw vs qw) are as follows: blood and lymphatic 71% vs 67%; hepatobiliary 7.5% vs 9.8%; asthenia/fatigue 7.5% vs 11%; GI 8.8% vs 8.5%; infections 7.5% vs 3.7%; respiratory, thoracic and mediastinal 5% vs 8.5%, metabolism and nutrition 4% vs 6%. For response data see table. No major difference was observed in drug exposure (based on AUC within one cycle) between the two dosing regimens. Conclusion: Dosing of GCI on a qw schedule produced a similar ORR to that obtained with the biw schedule. A comparable safety profile in both arms, and consistency with results of previous studies, suggests that the weekly combination of GCI may be an appropriate schedule for further studies evaluating this combination. OS and PFS data are not yet mature; updated efficacy and safety data will be presented. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-16-08.

Background The combination of gemcitabine, platinum and inhibition of DNA repair results in synergistic chemosensitivity in triple-negative and BRCA1-deficient breast cancer cell lines. This study was designed to assess efficacy, safety and predictors of response to iniparib, a small molecule whose mechanism of action is under investigation, in combination with GC in early-stage triple-negative and BRCA1/2 mutation-associated BC. Methods: This single-arm, phase II study (NCT00813956) enrolled patients with clinical stage I-IIIA (T ≥1cm by MRI) estrogen receptor-negative (≤ 5%), progesterone receptor-negative (≤ 5%), and HER2−negative or BRCA1/2 mutation-associated BC. Neoadjuvant gemcitabine (1000 mg/m2; IV; D1, 8), carboplatin (AUC 2; IV; D1, 8), and iniparib (5.6 mg/kg; IV; D1, 4, 8, 11) were given every 21 days for 4 cycles, until the protocol was amended to increase the treatment duration to 6 cycles with enrollment of 36 patients. The protocol was further amended to increase the patient number with expansion to additional centers. Prior to expansion, reporting of interim safety and efficacy results was specified. The primary endpoint is pathologic complete response (pCR), defined as the absence of invasive carcinoma in the breast and axilla. Pathologic response was assessed using the residual cancer burden (RCB) index. Secondary endpoints included safety, radiographic response by MRI, breast conservation eligibility and correlation of baseline gene expression with response. Results: The pre-expansion cohort consisted of 13 patients assigned to 4 cycles of treatment and 36 patients assigned to 6 cycles of treatment. Among these 49 patients (50 tumors), median tumor size is 35 mm, and median age is 48 years. The overall pCR rate is 34% (95% CI = 22–48); the pCR rate at 6 cycles is 41% (95% CI = 26–57). RCB 0/I was observed in 5/13 pts (38%; 95% CI = 18–64) treated with 4 cycles; 21/37 (57%; 95% CI = 41–71) treated with 6 cycles; and 9/9 pts (100%) with known BRCA1/2 mutations. Two pts experienced disease progression, two locoregional relapse, and three distant relapse. Among 45 tumors with Affymetrix-based RNA microarray gene expression data, 39/45 (87%) are classified as basal-like, 3/45 (7%) luminal B, and 3/45 (7%) normal breast-like. Most common G3/4 adverse events include neutropenia (31%), anemia (10%), and elevated ALT/AST (10%). Alopecia and chemotherapy-induced amenorrhea were uncommon. Analyses of secondary endpoints are ongoing and will be presented. Conclusions: Preoperative GC plus iniparib is active in the treatment of early-stage triple-negative and BRCA1/2 mutation-associated breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-14-08.

Poly(ADP-ribose) polymerase (PARP) inhibitors are currently in development for the treatment of cancer. PARP-1 and PARP-2 are important in the repair of DNA damage. PARP inhibitors used either as single agents or in combination with other cytotoxics, aim to increase efficacy of DNA damage. When PARP is inactivated in cells lacking functional BRCA1 or BRCA2, cells reach a high degree of genomic instability and die. Populations studied in ongoing and reported clinical trials include BRCA mutation-associated cancers, as well as sporadic breast cancers, ovarian cancers and other malignancies. In this review, PARP inhibitors undergoing clinical trial evaluation in humans (olaparib, iniparib, veliparib, rucaparib, MK-4827 and INO-1001) are discussed, with a focus on breast cancer, but also other tumors and the recently reported study results.

The success of endocrine therapies for hormone receptor-positive breast cancer and trastuzumab and lapatinib for targeting human epidermal growth factor receptor 2 (HER2)-positive tumors has paved the way for the clinical development of several other metastatic breast cancer (MBC)-targeted therapies. Although the benefit of the anti-VEGF (vascular endothelial growth factor) monoclonal antibody bevacizumab in the MBC setting has become a topic of debate, clinical trial results are accumulating, and phase 3 evaluations are ongoing for newer HER2-targeted agents (pertuzumab and trastuzumab-maytansine immunoconjugate) and VEGF-targeted agents (aflibercept), as well as dual, epidermal growth factor receptor/HER2-targeted agents (afatinib [BIBW 2992] and neratinib), multitargeted tyrosine kinase inhibitors (sunitinib and pazopanib), and mammalian target of rapamycin (everolimus) and poly (ADP-ribose) polymerase 1 inhibitors (iniparib, olaparib). These agents as well as other novel classes of anticancer agents are being tested in clinical trials with the potential of addressing unmet therapeutic needs in the MBC patient population. Cancer 2012;118: 3014–25. © 2011 American Cancer Society.

Triple negative breast cancer (TNBC) is an aggressive clinical phenotype characterized by lack of expression (or minimal expression) of estrogen receptor (ER) and progesterone receptor (PR) as well as an absence of human epidermal growth factor receptor–2 (HER2) overexpression. It shows substantial overlap with basal-type and BRCA1-related breast cancers, both of which also have aggressive clinical courses. However, this overlap is not complete, and the expression of ER, PR, and HER2 has been noted in basal-like tumors. TNBC also includes the normal-like subtype, and not all patients with TNBC harbor BRCA1 mutations. Because of its expression profile, TNBC is not amenable to treatment with hormone therapy or the anti-HER2 monoclonal antibody trastuzumab, and systemic treatment options are currently limited to cytotoxic chemotherapy. Overall survival, whether in early-stage or advanced disease, is poor compared with that in patients who have other phenotypes. A number of targeted approaches to TNBC are undergoing clinical evaluation, including the use of agents with poly(ADP-ribose) polymerase inhibitory properties such as iniparib (the United States Adopted Name for the investigational agent BSI-201), olaparib (AZD2281), and veliparib (ABT-888), antiangiogenic agents such as bevacizumab and sunitinib, and epidermal growth factor receptor blockers such as cetuximab and erlotinib. Encouraging results with some of these agents have been reported, thereby offering the promise for improved outcomes in patients with TNBC. The clinical characteristics of TNBC and clinical experience to date with novel targeted agents under development for this aggressive phenotype is reviewed.

Background: Inhibition of poly (ADP-ribose) polymerase-1 (PARP1), a key regulator of DNA repair and cell proliferation, potentiates the anti-tumor activity of DNA-damaging chemotherapy agents, including irinotecan, a topoisomerase inhibitor (Ossovskaya et al. AACR 2009). Combination of gemcitabine and carboplatin with the PARP inhibitor iniparib has demonstrated promising efficacy and safety in patients with triple-negative MBC (O'Shaughnessy et al. SABCS 2009). Single agent irinotecan is active in heavily pre-treated metastatic breast cancer (MBC), with response rates (RR) up to 23% (Perez et al. JCO 2004;22:2849). A Phase 1 dose-escalation study of iniparib in advanced solid tumors showed no dose-limiting toxicities (DLTs) at iniparib doses of 0.5 to 8.0 mg/kg (Kopetz et al. ASCO 2008). That study was expanded here to determine the maximum-tolerated dose (MTD) of irinotecan that can be used in combination with fixed dose iniparib in patients with locally advanced or MBC. Methods: Patients were treated with a 3+3 study design to determine safety of iniparib (8 mg/kg IV twice-weekly on Days 1, 4, 8, and 11 every 21 days) in combination with escalating doses of irinotecan (80 — 125 mg/m2 IV on Days 1 and 8 every 21 days). RRs were measured per modified RECIST criteria. Serial pharmacokinetic (PK) assessments were performed during Cycle 1, and archived paraffin-embedded tumor samples were collected to correlate markers of hypoxia (CAIX) with PARP1 expression (as measured by immunohistochemistry [IHC]) and response. Results: The median age of 34 patients who received therapy was 50 years (range, 32-84), and the median number of prior therapies was 2 (range, 0-6). Preliminary analysis show that tumors from 22 (65%) patients were ER-/PR-/HER2- (triple-negative), 10 (29%) were ER+/HER2-, and 1 (3%) was HER2+. One DLT of Grade 3 diarrhea with lower GI bleed was observed, thus establishing the optimal regimen from this study at 8 mg/kg iniparib + 125 mg/m2 irinotecan. Other toxicities included neutropenia, anemia and diarrhea. Of 26 patients evaluable for response, 5 (19%) had partial response (PR), 10 (38%) had stable disease (SD) for >4 cycles of therapy, and 9 (35%) developed progressive disease (PD) as best response. Of 10 patients who had reached 6 cycles at time of analysis, 5 (50%) had SD. Median follow-up time was 11 weeks. PK and IHC evaluations are ongoing and will be presented, along with mature response data. Conclusions: An MTD of 8 mg/kg iniparib and 125 mg/m2 irinotecan was identified in patients with MBC. Iniparib in combination with irinotecan was well tolerated and showed promising efficacy, with evidence of clinical benefit (RR + SD ≥6 cycles) in 50% in patients with treatment-refractory MBC. (ClinicalTrials.gov number, NCT00298675) Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-15-01.

Soft tissue sarcomas (STS) are aggressive tumors with a poor prognosis. Poly(ADP-ribose) polymerase (PARP)-1 inhibitors (PARPi) enhance the cytotoxic effects of radiation. In this study, we evaluated the effect of PARPi on survival and DNA damage of irradiated STS cells. For clonogenic assays, STS cell lines were irradiated with or without olaparib, iniparib or veliparib pretreatment. The effect of PARP inhibition on γ-H2AX and Rad51 foci formation, on PARP-1, phospho-ERK and cleaved caspase-3 protein expression and on cell cycle progression was evaluated on irradiated rhabdomyosarcoma cells pretreated with olaparib. The results from this work showed that PARPi induced significant radiosensitization in STS cells. Rhabdomyosarcoma cells showed the highest increase in radiosensitivity, with a radiosensitization enhancement ratio at 50% survival (ER50) of 3.41 with veliparib. All PARPi exerted a synergistic effect when combined with radiation. Fibrosarcoma cells showed an ER50 of 2.29 with olaparib. Leiomyosarcoma and liposarcoma cells showed their highest ER50 with veliparib (1.71 and 1.84, respectively). In rhabdomyosarcoma, olaparib enhanced the formation of radiation-induced γ-H2AX/Rad51 foci and PARP-1 cleavage, induced slightly increased expression of cleaved caspase-3 and reduced phospho-ERK expression. Moreover, the combination of olaparib and radiation resulted in a significantly enhanced cell cycle arrest in the G2/M phase compared to the two treatments alone. In conclusion, we have shown that PARPi are potent radiosensitizers of human STS cells. These results support the pursuit of further investigations into the effects of PARPi combined with radiation on STS.

Olaparib, a novel, orally active poly(ADP-ribose) polymerase (PARP) inhibitor, induced synthetic lethality in BRCA-deficient cells. A maximum tolerated dose and initial signal of efficacy in BRCA-deficient ovarian cancers have been reported. We therefore assessed the efficacy, safety, and tolerability of olaparib alone in women with BRCA1 or BRCA2 mutations and advanced breast cancer.Women (agedor=18 years) with confirmed BRCA1 or BRCA2 mutations and recurrent, advanced breast cancer were assigned to two sequential cohorts in a phase 2 study undertaken in 16 centres in Australia, Germany, Spain, Sweden, the UK, and the USA. The first cohort (n=27) was given continuous oral olaparib at the maximum tolerated dose (400 mg twice daily), and the second (n=27) was given a lower dose (100 mg twice daily). The primary efficacy endpoint was objective response rate (ORR). This study is registered with ClinicalTrials.gov, number NCT00494234.Patients had been given a median of three previous chemotherapy regimens (range 1-5 in cohort 1, and 2-4 in cohort 2). ORR was 11 (41%) of 27 patients (95% CI 25-59) in the cohort assigned to 400 mg twice daily, and six (22%) of 27 (11-41) in the cohort assigned to 100 mg twice daily. Toxicities were mainly at low grades. The most frequent causally related adverse events in the cohort given 400 mg twice daily were fatigue (grade 1 or 2, 11 [41%]; grade 3 or 4, four [15%]), nausea (grade 1 or 2, 11 [41%]; grade 3 or 4, four [15%]), vomiting (grade 1 or 2, three [11%]; grade 3 or 4, three [11%]), and anaemia (grade 1 or 2, one [4%]; grade 3 or 4, three [11%]). The most frequent causally related adverse events in the cohort given 100 mg twice daily were nausea (grade 1 or 2, 11 [41%]; none grade 3 or 4) and fatigue (grade 1 or 2, seven [26%]; grade 3 or 4, one [4%]).The results of this study provide positive proof of concept for PARP inhibition in BRCA-deficient breast cancers and shows a favourable therapeutic index for a novel targeted treatment strategy in patients with tumours that have genetic loss of function of BRCA1-associated or BRCA2-associated DNA repair. Toxicity in women with BRCA1 and BRCA2 mutations was similar to that reported previously in those without such mutations.AstraZeneca.

Ovarian carcinomas with mutations in the tumour suppressor BRCA2 are particularly sensitive to platinum compounds. However, such carcinomas ultimately develop cisplatin resistance. The mechanism of that resistance is largely unknown. Here we show that acquired resistance to cisplatin can be mediated by secondary intragenic mutations in BRCA2 that restore the wild-type BRCA2 reading frame. First, in a cisplatin-resistant BRCA2-mutated breast-cancer cell line, HCC1428, a secondary genetic change in BRCA2 rescued BRCA2 function. Second, cisplatin selection of a BRCA2-mutated pancreatic cancer cell line, Capan-1 (refs 3, 4), led to five different secondary mutations that restored the wild-type BRCA2 reading frame. All clones with secondary mutations were resistant both to cisplatin and to a poly(ADP-ribose) polymerase (PARP) inhibitor (AG14361). Finally, we evaluated recurrent cancers from patients whose primary BRCA2-mutated ovarian carcinomas were treated with cisplatin. The recurrent tumour that acquired cisplatin resistance had undergone reversion of its BRCA2 mutation. Our results suggest that secondary mutations that restore the wild-type BRCA2 reading frame may be a major clinical mediator of acquired resistance to platinum-based chemotherapy.

Advances in surgical and medical treatments for ovarian cancer have improved prognoses. Platinum drugs in particular are pivotal for the medical treatment of ovarian cancer. However, previous studies have revealed that some histological subtypes, such as clear cell carcinoma, are resistant to medical treatment, including that with platinum drugs. Consequently, the clinical prognosis of advanced clear cell carcinoma is remarkably inferior, primarily because of its chemoresistant behavior. The prevalence of clear cell carcinoma is approximately 5 % in the West, but in Japan, its prevalence is particularly high, at approximately 25 %. Current medical treatments for advanced clear cell carcinoma are difficult to administer, and they have poor efficacy, warranting the development of novel target-based therapies. In this review, we describe medical treatments for clear cell carcinoma and discuss future prospects for therapy. In particular, we focus on the mechanism of platinum resistance in clear cell carcinoma, including the role of annexin A4, one of the most investigated factors of platinum resistance, as well as the mutant genes and overexpressed proteins such as VEGF, PI3K/AKT/mTOR signaling pathway, ARID1A, hepatocyte nuclear factor-1β, ZNF217. We also review targeted molecular therapeutics for epithelial ovarian cancer and discuss their role in clear cell carcinoma treatment. We review the drugs targeting angiogenesis (bevacizumab, sorafenib, and pazopanib), growth factors (gefitinib, erlotinib, lapatinib, trastuzumab, and AMG479), and signaling pathways (temsirolimus, dasatinib, and imatinib), and other drugs (oregovomab, volociximab, and iniparib). This current review summarizes and discusses the clinical significance of these factors in ovarian clear cell carcinoma as well as their potential mechanisms of action. It may provide new integrative understanding for future studies on their exact role in ovarian clear cell carcinoma.

Purpose Trabectedin induces synthetic lethality in tumor cells carrying defects in homologous recombinant DNA repair. We evaluated the effect of concomitant inhibition of nucleotide-excision repair and poly (ADP-ribose) polymerase (PARP) activity with trabectedin and PARP inhibitors, respectively, and whether the synthetic lethality effect had the potential for a synergistic effect in breast cancer cell lines. Additionally, we investigated if this approach remained effective in BRCA1-positive breast tumor cells. Methods We have evaluated the in vitro synergistic effect of combinations of trabectedin and three different PARP inhibitors (veliparib, olaparib, and iniparib) in four breast cancer cell lines, each presenting a different BRCA1 genetic background. Antiproliferative activity, DNA damage, cell cycle perturbations and poly(ADP-ribosyl)ation were assessed by MTT assay, comet assay, flow cytometry and western blot, respectively. Results The combination of trabectedin and olaparib was synergistic in all the breast cancer cell lines tested. Our data indicated that the synergy persisted regardless of the BRCA1 status of the tumor cells. Combination treatment was associated with a strong accumulation of double-stranded DNA breaks, G2/M arrest, and apoptotic cell death. Synergistic effects were not observed when trabectedin was combined with veliparib or iniparib. Conclusion Collectively, our results indicate that the combination of trabectedin and olaparib induces an artificial synthetic lethality effect that can be used to kill breast cancer cells, independent of BRCA1 status.

The introduction of PARP inhibitors as active agents to inhibit DNA repair was a revolution in cancer therapeutics. However, this approach only has shown results for a short duration in the majority of cases, due to secondary mutations and promoter gene methylation. Studies of patients with triple-negative breast cancer in particular, treated with PARP inhibitors show benefit from the agents for only a short time, until the tumor shows resistance and further the therapy fails. [1,2,3,4] We discuss a case report of a patient with Stage IV refractory and resistant BRCA1 mutated triple-negative breast cancer, who responded to a combinational therapy, consisting of a PARP inhibitor and an epigenetic modifier. The purpose of this case report is to show that combination treatment of epigenetic therapies and PARP inhibitors is synergistic and results in improved clinical outcomes. The patient in this case had already exhausted a PARP inhibitor, which was evident by the presence of excessive BRCA positive altered circulating tumor DNA (ctDNA). The initial finding was 93% mutation allele fraction (MAF) of BRCA gene on liquid biopsy by Guardant360 laboratory. The liquid biopsy for ctDNA was repeated after two weeks of combination therapy, and showed complete disappearance (resolution of positive BRCA gene in ctDNA), reflecting a synergism by proposed modulation of resistance, as mechanism of action. The response reflects the epigenetic therapy as back-bone of treatment, as no other changes were made that could account for the response. To our knowledge, this is the first study of combinational therapies in a human. Our finding in this case could potentially change the standard of care in treating BRCA positive tumors, by providing a superior treatment to current standards. References 1. Veliparib Falls Short in Phase III NSCLC, TNBC Trials. (2017). Retrieved September 05, 2017, from http://www.onclive.com/web-exclusives/veliparib-falls-short-in-phase-iii-nsclc-tnbc-trials 2. Dziadkowiec, K. N., Gąsiorowska, E., Nowak-Markwitz, E., & Jankowska, A. (2016). PARP inhibitors: review of mechanisms of action and BRCA1/2 mutation targeting. Przeglaąd Menopauzalny = Menopause Review, 15(4), 215-219. http://doi.org/10.5114/pm.2016.65667 3. Livraghi, L., & Garber, J. E. (2015). PARP inhibitors in the management of breast cancer: current data and future prospects. BMC Medicine, 13(1). doi:10.1186/s12916-015-0425-1 4. Oshaughnessy, J., Schwartzberg, L., Danso, M. A., Miller, K. D., Rugo, H. S., et al. (2014). Phase III Study of Iniparib Plus Gemcitabine and Carboplatin Versus Gemcitabine and Carboplatin in Patients With Metastatic Triple-Negative Breast Cancer. Journal of Clinical Oncology, 32(34), 3840-3847. doi:10.1200/jco.2014.55.2984 Citation Format: M.A. Nezami, Jessica Garner. Biological modulation of PARP inhibition in triple negative breast cancer: A case report of combinational approach implementing histone deacetylase inhibition with PARP inhibition in advanced breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr LB-A25.

Iniparib is an investigational agent with antitumor activity of controversial mechanism of action. Two previous trials in advanced triple-negative breast cancer (TNBC) in combination with gemcitabine and carboplatin showed some evidence of efficacy that was not confirmed. This phase II randomized neoadjuvant study was designed to explore its activity and tolerability with weekly paclitaxel (PTX) as neoadjuvant treatment in TNBC patients. 141 patients with Stage II-IIIA TNBC were randomly assigned to receive PTX (80 mg/m(2), d1; n = 47) alone or in combination with iniparib, either once-weekly (PWI) (11.2 mg/kg, d1; n = 46) or twice-weekly (PTI) (5.6 mg/kg, d1, 4; n = 48) for 12 weeks. Primary endpoint was pathologic complete response (pCR) in the breast. pCR rate was similar among the three arms (21, 22, and 19 % for PTX, PWI, and PTI, respectively). Secondary efficacy endpoints were comparable: pCR in breast and axilla (21, 17, and 19 %); best overall response in the breast (60, 61, and 63 %); and breast conservation rate (53, 54, and 50 %). Slightly more patients in the PTI arm presented grade 3/4 neutropenia (4, 0, and 10 %). Grade 1/2 (28, 22, and 29 %), but no grade 3/4 neuropathy, was observed. There were no differences in serious adverse events and treatment-emergent adverse events leading to treatment discontinuation among the three arms. Addition of iniparib to weekly PTX did not add relevant antitumor activity or toxicity. These results do not support further evaluation of the combination of iniparib at these doses plus paclitaxel in early TNBC.

Background: Mutation carriers of BRCA1 and BRCA2 are well known to develop early onset breast cancer, with loss of the second allele occurring in the development of the tumor. However, by array comparative genomic hybridization (aCGH) studies, some sporadic breast cancers have a similar “genetic landscape” as BRCA-mutation carriers, showing large losses and gains across the genome. We have now identified that DNA repair defects involving the BRCA1-BRCA2 pathway can occur in the absence of mutations in either gene and in the absence of a deficiency in either protein. Methods: Fresh human breast cancer samples were irradiated, ex-vivo, to look for the ability to assemble RAD51 protein macrocomplexes or foci. Primary breast cancer specimens were obtained from consented patients with non-metastatic, invasive carcinomas following lumpectomy or mastectomy, without neoadjuvant cytotoxic or hormonal therapy. A single cell suspension was prepared from the tumor, with one half irradiated to 10Gy and the other half mock-treated. After 4h, cells were mounted, fixed on slides, and stained with anti-Rad51, anti-BRCA1, and anti-γH2AX antibodies. At least 200 nuclei were examined and scored using confocal microscopy. A failure to induce RAD51 nuclear foci by 2-fold after ionizing radiation was designated as defective in homologous recombination (HR). Results: For the 71 patient samples analyzed, we have 14 triple-negative tumors, of which 6 are HR-defective (42.8%); for Her2-amplified tumors, we have 6/19 (31.6%) that are HR-defective and for ER+ tumors 6/38 (15.8%). The overall incidence of HR-defective tumors is 18/71 (25.3%), which is substantially higher than we would have expected. Known mutation carriers were not included in the study, since these samples are BRCA-HR-defective in all cases we have tested. For the more recently acquired samples, we have undertaken additional tests to characterize the tumors: short-term growth assays in response to mitomycinC to validate that HR-defective tumors are indeed sensitive to cross-linking agents; and, a pilot analysis to study aCGH patterns in HR-defective tumors. The latter studies have compared 6 repair-deficient and 6 repair-proficient tumors using unsupervised cluster analysis of large block deletions or large block copy number increase, which clearly reveal that large block alterations are linked to repair-deficient tumors. Conclusions: There is a significant incidence of BRCA-HR defective sporadic breast cancers, as determined by RAD51 function in response to ionizing radiation plus genetic landscape alterations using aCGH. The pool of breast cancers that are susceptible to repair targeting strategies is larger than expected and is not readily defined by conventional diagnostic biomarker classification. These findings may account for the failure of the recent phase III study of the addition of iniparib to carboplatin and gemcitabine in triple-negative cancer as only a minority of the tumors will be susceptible to this targeting strategy. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD10-02.

Purpose There is a lack of treatments providing survival benefit for patients with metastatic triple-negative breast cancer (mTNBC), with no standard of care. A randomized phase II trial showed significant benefit for gemcitabine, carboplatin, and iniparib (GCI) over gemcitabine and carboplatin (GC) in clinical benefit rate, response rate, progression-free survival (PFS), and overall survival (OS). Here, we formally compare the efficacy of these regimens in a phase III trial. Patients and Methods Patients with stage IV/locally recurrent TNBC who had received no more than two previous chemotherapy regimens for mTNBC were randomly allocated to gemcitabine 1,000 mg/m2 and carboplatin area under the curve 2 (days 1 and 8) alone or GC plus iniparib 5.6 mg/kg (days 1, 4, 8, and 11) every 3 weeks. Random assignment was stratified by the number of prior chemotherapies. The coprimary end points were OS and PFS. Patients receiving GC could cross over to iniparib on progression. Results Five hundred nineteen patients were randomly assigned (261 GCI; 258 GC). In the primary analysis, no statistically significant difference was observed for OS (hazard ratio [HR] = 0.88; 95% CI, 0.69 to 1.12; P = .28) nor PFS (HR = 0.79; 95% CI, 0.65 to 0.98; P = .027). An exploratory analysis showed that patients in the second-/third-line had improved OS (HR = 0.65; 95% CI, 0.46 to 0.91) and PFS (HR = 0.68; 95% CI, 0.50 to 0.92) with GCI. The safety profile for GCI was similar to GC. Conclusion The trial did not meet the prespecified criteria for the coprimary end points of PFS and OS in the ITT population. The potential benefit with iniparib observed in second-/third-line subgroup warrants further evaluation.

The repair of DNA double-strand breaks is a critical cellular mechanism that exists to ensure genomic stability. DNA double-strand breaks are the most deleterious type of insult to a cells genetic material and can lead to genomic instability, apoptosis or senescence. Incorrectly repaired DNA double-strand breaks have the potential to produce chromosomal translocations and genomic instability, potentially leading to cancer. The prevalence of DNA double-strand breaks in cancer due to unregulated growth and errors in repair opens up a potential therapeutic window in the treatment of cancers. The cellular response to DNA double-strand breaks is comprised of two pathways to ensure DNA breaks are repaired: homologous recombination and non-homologous end joining. Identifying chemotherapeutic compounds targeting proteins involved in these DNA repair pathways has shown promise as a cancer therapy for patients, either as a monotherapy or in combination with genotoxic drugs. From the beginning, there have been a number of chemotherapeutic compounds that have yielded successful responses in the clinic, a number that have failed (CGK733 and Iniparib) and a number of promising targets for future studies identified. This review looks in detail at how the cell responds to these DNA double-strand breaks and investigates the chemotherapeutic avenues that have been and are currently being explored to target this repair process.

Several drugs targeting poly(ADP-ribose) polymerase (PARP) enzymes are under development. Responses have been observed in patients with germline mutations in BRCA1 and BRCA2, with further data supporting antitumour activity of PARP inhibitors in sporadic ovarian cancer. Strategies to identify other predictive biomarkers remain under investigation. Iniparib was purported to be a PARP inhibitor that showed promising results in randomized phase II trials in patients with triple-negative breast cancer. Negative results from a phase III study in this disease setting, however, tempered enthusiasm for this agent. Recently, data from in vitro experiments suggest that iniparib is not only structurally distinct from other described PARP inhibitors, but is also a poor inhibitor of PARP activity. In this context, the negative iniparib phase III data might have erroneously promulgated the notion that PARP inhibition is not an effective therapeutic strategy. Here, we scrutinize the development of iniparib from preclinical studies to registration trials, and identify and discuss the pitfalls in the development of anticancer drugs to prevent future late-stage trial failures.

PARP inhibitors, both as monotherapy and in combination with cytotoxic drugs, are currently undergoing clinical trials in several different cancer types. In this investigation, we compared the antiproliferative activity of two PARP/putative PARP inhibitors, i.e., olaparib and iniparib, in a panel of 14 breast cancer cell lines (seven tripe-negative and seven non-triple-negative). In almost all cell lines investigated, olaparib was a more potent inhibitor of cell growth than iniparib. Inhibition by both drugs was cell line-dependent and independent of the molecular subtype status of the cells, i.e., whether cells were triple-negative or non-triple negative. Although the primary target of PARP inhibitors is PARP1, no significant association was found between baseline levels of PARP1 activity and inhibition with either agent. Similarly, no significant correlation was evident between sensitivity and levels of CDK1, BRCA1 or miR-182. Combined addition of olaparib and either the CDK1 inhibitor, RO-3306 or a pan HER inhibitor (neratinib, afatinib) resulted in superior growth inhibition to that obtained with olaparib alone. We conclude that olaparib, in contrast to iniparib, is a strong inhibitor of breast cancer cell growth and may have efficacy in breast cancer irrespective of its molecular subtype, i.e., whether HER2-positive, estrogen receptor (ER)-positive or triple-negative. Olaparib, in combination with a selective CDK1 inhibitor or a pan HER inhibitor, is a potential new approach for treating breast cancer.

Background Mutations in the DNA damage response (DDR) factors, breast cancer 1 (BRCA1) and BRCA2, sensitize tumor cells to poly(ADP-ribose) polymerase (PARP) inhibitors. The ataxia telangiectasia mutated (ATM) kinase is a key DDR protein whose heterozygous germline mutation is a moderate–risk factor for developing breast cancer. In this study, we examined whether ATM inactivation in breast cancer cell lines confers sensitivity to PARP inhibitors. Methods Wild-type BRCA1/2 breast cancer cells (i.e., MCF-7 and ZR-75-1 lines) were genetically manipulated to downregulate ATM expression then assayed for cytostaticity/cytotoxicity upon treatment with PARP inhibitors, olaparib and iniparib. Results When ATM-depleted cells and their relative controls were treated with olaparib (a competitive PARP-1/2 inhibitor) and iniparib (a molecule originally described as a covalent PARP-1 inhibitor) a different response to the two compounds was observed. ATM-depletion sensitized both MCF-7 and ZR-75-1 cells to olaparib-treatment, as assessed by short and long survival assays and cell cycle profiles. In contrast, iniparib induced only a mild, ATM-dependent cytostatic effect in MCF-7 cells whereas ZR-75-1 cells were sensitive to this drug, independently of ATM inactivation. These latest results might be explained by recent observations indicating that iniparib acts with mechanisms other than PARP inhibition. Conclusions These data indicate that ATM-depletion can sensitize breast cancer cells to PARP inhibition, suggesting a potential in the treatment of breast cancers low in ATM protein expression/activity, such as those arising in mutant ATM heterozygous carriers.

Triple-negative breast cancer (TNBC) accounts for 15% to 20% of breast cancers. It is a heterogeneous disease, not only on the molecular level, but also on the pathologic and clinical levels. TNBC is associated with a significantly higher probability of relapse and poorer overall survival in the first few years after diagnosis when compared with other breast cancer subtypes. This is observed despite its usual high sensitivity to chemotherapy. In the advanced setting, responses observed with chemotherapy lack durability. Early-stage clinical studies suggested impressive potential when a poly (ADP-ribose) polymerase (PARP) inhibitor is given for the treatment of advanced TNBC with BRCA gene dysfunction. The molecular complexity of TNBC has led to proposed subclassifications, which will be of great value for the development of targeted therapies. In this review, we discuss the biology of TNBC at the pathologic and the molecular levels. We also elaborate on the role of systemic therapies and the results of the first phase III clinical trial evaluating the addition of iniparib, a novel investigational anticancer agent that does not possess characteristics typical of the PARP inhibitor class, in combination with chemotherapy in advanced TNBC.

Deeper understanding of DNA repair mechanisms and their potential value as therapeutic targets in oncology heralded the clinical development of poly (ADP-ribose) polymerase (PARP) inhibitors. Although initially developed to exploit synthetic lethality in models of cancer associated with defective DNA repair, our burgeoning knowledge of PARP biology has resulted in these agents being exploited both in cancer with select chemotherapeutic agents and in non-malignant diseases. In this review article, we briefly review the mechanisms of DNA repair and pre-clinical development of PARP inhibitors before discussing the clinical development of the various PARP inhibitors in depth.

Purpose: Poly(ADP-ribose) polymerase (PARP) inhibitors are undergoing extensive clinical testing for their single-agent activity in homologous recombination (HR)-deficient tumors and ability to enhance the action of certain DNA-damaging agents. Compared with other PARP inhibitors in development, iniparib (4-iodo-3-nitrobenzamide) is notable for its simple structure and the reported ability of its intracellular metabolite 4-iodo-3-nitrosobenzamide to covalently inhibit PARP1 under cell-free conditions. The present preclinical studies were conducted to compare the actions iniparib with the more extensively characterized PARP inhibitors olaparib and veliparib. Experimental Design: The abilities of iniparib, olaparib, and veliparib to (i) selectively induce apoptosis or inhibit colony formation in HR-deficient cell lines, (ii) selectively sensitize HR-proficient cells to topoisomerase I poisons, and (iii) inhibit formation of poly(ADP-ribose) polymer (pADPr) in intact cells were compared. Results: Consistent with earlier reports, olaparib and veliparib selectively induced apoptosis and inhibited colony formation in cells lacking BRCA2 or ATM. Moreover, like earlier generation PARP inhibitors, olaparib and veliparib sensitized cells to the topoisomerase I poisons camptothecin and topotecan. Finally, olaparib and veliparib inhibited formation of pADPr in intact cells. In contrast, iniparib exhibited little or no ability to selectively kill HR-deficient cells, sensitize cells to topoisomerase I poisons, or inhibit pADPr formation in situ. In further experiments, iniparib also failed to sensitize cells to cisplatin, gemcitabine, or paclitaxel. Conclusions: While iniparib kills normal and neoplastic cells at high (>40 μmol/L) concentrations, its effects are unlikely to reflect PARP inhibition and should not be used to guide decisions about other PARP inhibitors. Clin Cancer Res; 18(6); 1655–62. ©2012 AACR.

Summary Epithelial carcinomas in general arise as a result of the acquisition of and selection for multiple mutations in a parental somatic cell clone within the tissues of the primary organ of origin. In the last two decades genome caretakers, which function in key areas of DNA damage response, have been recognized as important tumour suppressor genes. Inactivating mutations in these genes occur both as germline and/or somatic mutations with increasing evidence of epigenetic silencing as an additional cause of loss of function. In any event, loss of function in a tumour cell pre-cursor clone leads to accelerated mutation acquisition and underpins the aetiology of the tumour. With increasing understanding of the complex network that is the DNA damage response, signaling pathways already recognized to be central to the establishment of the cancer phenotype are gaining additional roles as controllers of DNA repair. This has relevance to identification of wider populations of patients with tumours susceptible to approaches that target DNA repair deficiency. These have classically been with DNA damaging chemotherapy but the recently developed small molecule inhibitors of DNA repair enzymes such as Poly-ADP polymerases PARP-1 and PARP-2 have been shown to target tumour deficiencies in DNA repair as well sensitizing to DNA damaging therapeutics such as radiation and chemotherapy. Early phase trials with efficacy endpoints have been presented for the PARP inhibitors AG014699, olaparib, veliparib, iniparib and MK4827. The results of the first phase II trials exploring monotherapy PARP inhibitor strategies, which are based on revisiting the concept of synthetic lethality, have emerged and are reviewed herein. The clinical trials that have or are exploring combinations with DNA damaging therapy in these contexts are discussed with particular reference to breast cancer, as are biomarkers that have been proposed and are being investigated to develop optimal drug schedule and patient selection criteria for these DNA repair targeting approaches.

Tumor resistance remains a major clinical challenge. Numerous pathways are under investigation to determine how best to target therapies to specific mutations in tumor biology and circumvent resistance. Agents in development include inhibitors of the poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) pathway, such as iniparib, olaparib, and veliparib; the PI3K/Akt/mTOR pathway inhibitor everolimus; and the Src family tyrosine kinase inhibitor dasatinib. Research is ongoing to determine whether patients with specific biochemical attributes, such as the presence of a BRCA1 or BRCA2 mutation, will have a better response to targeted therapy and whether targeted agents act synergistically with chemotherapeutic agents.

Whereas target-specific drugs are available for treating ERBB2-overexpressing and hormone receptor-positive breast cancers, no tailored therapy exists for hormone receptor- and ERBB2-negative (“triple-negative”) mammary carcinomas. Triple-negative tumors account for 15% of all breast cancers and frequently harbor defects in DNA double-strand break repair through homologous recombination (HR), such as BRCA1 dysfunction. The DNA-repair defects characteristic of BRCA1-deficient cells confer sensitivity to poly(ADP-ribose) polymerase 1 (PARP1) inhibition, which could be relevant to treatment of triple-negative tumors. To evaluate PARP1 inhibition in a realistic in vivo setting, we tested the PARP inhibitor AZD2281 in a genetically engineered mouse model (GEMM) for BRCA1-associated breast cancer. Treatment of tumor-bearing mice with AZD2281 inhibited tumor growth without signs of toxicity, resulting in strongly increased survival. Long-term treatment with AZD2281 in this model did result in the development of drug resistance, caused by up-regulation of Abcb1a / b genes encoding P-glycoprotein efflux pumps. This resistance to AZD2281 could be reversed by coadministration of the P-glycoprotein inhibitor tariquidar. Combination of AZD2281 with cisplatin or carboplatin increased the recurrence-free and overall survival, suggesting that AZD2281 potentiates the effect of these DNA-damaging agents. Our results demonstrate in vivo efficacy of AZD2281 against BRCA1-deficient breast cancer and illustrate how GEMMs of cancer can be used for preclinical evaluation of novel therapeutics and for testing ways to overcome or circumvent therapy resistance.

Lurbinectedin (PM1183) is a new tetrahydroisoquinoline derivative currently evaluated in phase II trials in BRCA1-mutated breast cancer and NSCLC patients. Two pivotal trials (in platinum-resistant ovarian cancer and in SCLC) will be launched in 2015. PM1183 shows antitumor activity against a wide variety of tumor cells with mean IC50 values in the low nanomolar range. In living cells, PM1183 inhibits trans-activated transcription and blocks NER-dependent DNA repair inducing the formation of dsDNA breaks and the collapse of replication forks that need to be repaired by homologous recombination (HR). As expected, PM1183 is more active against homologous recombination (HR)-deficient cell lines. In this work, we evaluated the in vitro antitumor effect of PM1183 when combined with the PARP inhibitors ABT-88 (Veliparib, PARP-1 and -2), AZD-2281 (Olaparib, PARP-1), BSI-201 (Iniparib, PARP-1) and BMN-673 (PARP-1 and -2) (Selleck Chemicals, Houston, TX, USA) in a panel of human breast carcinoma cells with different BRCA1 status, including MCF-7 (BRCA1 +/+), MDA-MB-231 (BRCA1 +/-), HCC-1937 (BRCA1 -/-) and MDA-MB-436 (BRCA1 -/-). The combination index (CI) of each different drug-drug combination was calculated by applying the Chou and Talalay method. Different degrees of synergism (CI < 1) were recorded when PM1183 was combined with AZD-2281 (Olaparib) and BMN-673, depending on the tumor cell line and the conditions tested. The highest degree of synergism with Olaparib was observed in MDA-MB-436 cells followed by MDA-MB-231, MCF7 and HCC-1937 cells. The highest degree of synergism with BMN-673 was observed in MCF-7 cells followed by MDA-MB-231 and HCC-1937 cells. In MDA-MB-231 cells, both combinations led to a synergistic induction of γ-H2AX expression and PARP-1 cleavage, as analyzed by western blot. Collectively, our results indicate that the combination of PM1183 and PARP inhibitors (Olaparib and BMN673) induces an artificial synthetic lethality that can be advantageously used to kill several breast cancer cells, independently from their BRCA1 status. Citation Format: Gema Santamaría, Sonia Avila, Victoria Moneo, Carmen Cuevas, Luis F. García-Fernández, Carlos M. Galmarini. Synergistic combination of lurbinectedin and PARP inhibitors in breast cancer tumor cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2520. doi:10.1158/1538-7445.AM2015-2520

Background: Increased tumor infiltrating lymphocytes (TILs) are prognostic and predictive of therapy response in TNBC. CIBERSORT, a highly novel ‘in silico flow cytometry’ gene expression-based method, can assess the overall immune content and relative levels of distinct leukocyte subsets in tumors. Methods: We applied CIBERSORT to PrECOG 0105, a neoadjuvant trial of carboplatin, gemcitabine and iniparib for patients with clinical stage I-IIIA TN or BRCA1/2 mutation-associated BC. H&E tumor sections from pre-therapy biopsies were evaluated for density of stromal (sTILs) and intratumoral (iTILs) lymphocytes. Pathologic response was assessed at definitive surgery. Overall immune content and fractions of 23 distinct leukocyte subsets were derived from Affymetrix U133 plus 2.0 arrays, using CIBERSORT. Using an input matrix of reference gene expression signatures of 23 purified leukocytes, this methodology can infer an unknown fraction of each cell type from tissue expression profiling, yielding a p value for deconvolution. All patients had BRCA1/2 genotyping and levels of tumor genomic instability were assessed by the homologous recombination deficiency (HRD) assay. Results: 57 pts had gene expression and TILs assessment. TILs, sTILs, and iTILs were significantly associated with a measure of absolute immune content determined by CIBERSORT, termed an ‘immune score’ (R 0.73, p Conclusions: Neoadjuvant platinum-based therapy response significantly associates with both iTILs and CIBERSORT immune score. A measure of global genomic instability (HRD score) significantly associates with immune score alone. Enumeration of 23 leukocyte subsets in therapy-naïve TNBC by CIBERSORT revealed three distinct cell types that significantly predict pCR, two of which also associate with genomic instability. These results suggest an intimate interplay between genomic instability and immune infiltration, potentially shaping adaptive anti-tumor humoral immune responses, and thereby affecting neoadjuvant response in TNBC. Citation Format: Shaveta Vinayak, Aaron Newman, Sylvia Adams, Anosheh Afghahi, Kristin C Jensen, Sunil S Badve, James M Ford, Ash A Alizadeh, Melinda L Telli. Deconvoluting immune cell populations using ‘in silico flow cytometry’ with CIBERSORT: Association with neoadjuvant therapy response and genomic instability in TNBC [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-04-03.