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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.

INTRODUCTION Poly (ADP-ribose) polymerase inhibitors (PARPi) are already part of the armamentarium of drugs available against ovarian and breast cancer. There is less data available on the efficacy of these drugs in the treatment of non-small cell lung cancer (NSCLC). AREAS COVERED The authors have analyzed the preclinical studies that justified the use of PARPi in NSCLC. They then evaluate the in vivo efficacy of the combination of these drugs with chemotherapy, radiotherapy, and immunotherapy. EXPERT OPINION Data from clinical trials available to date have discouraged the use of PARPi in association with chemotherapy or radiotherapy in NSCLC. The knowledge available to date opens the door to the use of PARPi in association with immunotherapy. In fact, the activity of these drugs would not be based only on direct cytotoxic action, but also on the modification of the intra-tumor microenvironment, in particular by increasing the expression of PD-L1 on tumor cells. This action might potentially enhance available treatments with a modest increase in toxicity.

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.

Currently women that have a hereditary breast cancer predisposition face screening, chemoprevention, and risk-reducing surgery as options for preventing the disease. Bilateral preventive oophorectomy, combined with either MRI screening or a bilateral preventive mastectomy, can contribute considerably to a better life expectancy. Bilateral prophylactic mastectomy can reduce the risk of breast cancer by up to 95% in BRCA1/BRCA2 mutation carriers. There are two important works that must be considered seminal in the treatment of hereditary breast cancer mainly BRCA1/2 carriers. Wesierska-Gądek et al. have shown that using PARP inhibitors could be relevant in carriers of BRCA1\2 mutations based on the knowledge that BRCA1/2-mutant cells are hypersensitive to inactivation of poly(ADP-ribose) polymerase 1 (PARP-1). Another seminal paper published by Arun et al. in 2015 comparing three different PARP inhibitors such as the ABT-888 (Veliparib), BSI-201 (Iniparib), and AZD228 (Olaparib) demonstrated that they have anti-proliferative effects in breast cancer cell lines with BRCA1 or BRCA2 mutations. An interesting observation from this study was that AZD228 (Olaparib) was the most potent PARP inhibitor but only in those cells that have allelic loss.

Background Gene expression signatures for the prediction of differential survival of patients undergoing anti-cancer therapies are of great interest because they can be used to prospectively stratify patients entering new clinical trials, or to determine optimal treatment for patients in more routine clinical settings. Unlike prognostic signatures however, predictive signatures require training set data from clinical studies with at least two treatment arms. As two-arm studies with gene expression profiling have been rarer than similar one-arm studies, the methodology for constructing and optimizing predictive signatures has been less prominently explored than for prognostic signatures. Results Focusing on two “use cases” of two-arm clinical trials, one for metastatic colorectal cancer (CRC) patients treated with the anti-angiogenic molecule aflibercept, and the other for triple negative breast cancer (TNBC) patients treated with the small molecule iniparib, we present derivation steps and quantitative and graphical tools for the construction and optimization of signatures for the prediction of progression-free survival based on cross-validated multivariate Cox models. This general methodology is organized around two more specific approaches which we have called subtype correlation (subC) and mechanism-of-action (MOA) modeling, each of which leverage a priori knowledge of molecular subtypes of tumors or drug MOA for a given indication. The tools and concepts presented here include the so-called differential log-hazard ratio, the survival scatter plot, the hazard ratio receiver operating characteristic, the area between curves and the patient selection matrix. In the CRC use case for instance, the resulting signature stratifies the patient population into “sensitive” and “relatively-resistant” groups achieving a more than two-fold difference in the aflibercept-to-control hazard ratios across signature-defined patient groups. Through cross-validation and resampling the probability of generalization of the signature to similar CRC data sets is predicted to be high. Conclusions The tools presented here should be of general use for building and using predictive multivariate signatures in oncology and in other therapeutic areas.

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.

BRCA1/2-mutant cells are hypersensitive to inactivation of poly(ADP-ribose) polymerase 1 (PARP-1). We recently showed that inhibition of PARP-1 by NU1025 is strongly cytotoxic for BRCA1-positive BT-20 cells, but not BRCA1-deficient SKBr-3 cells. These results raised the possibility that other PARP-1 inhibitors, particularly those tested in clinical trials, may be more efficacious against BRCA1-deficient SKBr-3 breast cancer cells than NU1025. Thus, in the presented study the cytotoxicity of four PARP inhibitors under clinical evaluation (olaparib, rucaparib, iniparib and AZD2461) was examined and compared to that of NU1025. The sensitivity of breast cancer cells to the PARP-1 inhibition strongly varied. Remarkably, BRCA-1-deficient SKBr-3 cells were almost completely insensitive to NU1025, olaparib and rucaparib, whereas BRCA1-expressing BT-20 cells were strongly affected by NU1025 even at low doses. In contrast, iniparib and AZD2461 were cytotoxic for both BT-20 and SKBr-3 cells. Of the four tested PARP-1 inhibitors only AZD2461 strongly affected cell cycle progression. Interestingly, the anti-proliferative and pro-apoptotic potential of the tested PARP-1 inhibitors clearly correlated with their capacity to damage DNA. Further analyses revealed that proteomic signatures of the two studied breast cancer cell lines strongly differ, and a set of 197 proteins was differentially expressed in NU1025-treated BT-20 cancer cells. These results indicate that BT-20 cells may harbor an unknown defect in DNA repair pathway(s) rendering them sensitive to PARP-1 inhibition. They also imply that therapeutic applicability of PARP-1 inhibitors is not limited to BRCA mutation carriers but can be extended to patients harboring deficiencies in other components of the pathway(s).

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.

Background Iniparib is a novel anticancer agent initially considered a poly (ADP-ribose) polymerase (PARP) inhibitor, but subsequently shown to act via non-selective protein modification through cysteine adducts. This randomized phase II study investigated the addition of iniparib to gemcitabine–cisplatin in metastatic non-small-cell lung cancer (NSCLC) patients. Patients and methods Patients with histologically confirmed stage IV NSCLC were randomized 2 : 1 to receive gemcitabine (1250 mg/m2, days 1/8) and cisplatin (75 mg/m2, day 1) with [gemcitabine/cisplatin/iniparib (GCI)] or without [gemcitabine/cisplatin (GC)] iniparib (5.6 mg/kg, days 1/4/8/11) every 3 weeks for six cycles. The primary end point was the overall response rate (ORR). Secondary objectives included progression-free survival (PFS), overall survival (OS), and safety. The study was not designed for formal efficacy comparison, the control arm being to benchmark results against the literature. Results One hundred and nineteen patients were randomized (39 GC and 80 GCI). More GCI patients were male (80% GCI and 67% GC) and had PS 0 (61% GCI and 49% GC). The ORR was 25.6% [95% confidence interval (CI) 13.0%–42.1%] with GC versus 20.0% (95% CI 11.9%–30.4%) with GCI, which did not allow rejection of the null hypothesis (ORR with GCI ≤20%; P = 0.545). Median PFS was 4.3 (95% CI 2.8–5.6) months with GC and 5.7 (95% CI 4.6–6.6) months with GCI (hazard ratio 0.89, 95% CI 0.56–1.40). Median OS was 8.5 (95% CI 5.5 to not reached) months with GC, and 12.0 (95% CI 8.9–17.1) months with GCI (hazard ratio 0.78, 95% CI 0.48–1.27). More GCI patients received second-line treatment (51% GC and 68% GCI). Toxicity was similar in the two arms. Grade 3–4 toxicities included asthenia (28% GC and 8% GCI), nausea (3% GC and 14% GCI), and decreased appetite (10% in each). Conclusions Addition of iniparib to GC did not improve ORR over GC alone. The GCI safety profile was comparable to GC alone. Imbalances in PS and gender distribution may have impacted study results regarding PFS and OS. Trial Registration ClinicalTrial.gov Identifier NCT01086254.

Metastatic triple-negative breast cancer (mTNBC) represents 15% of invasive breast cancers. Prognosis is poor, and there is no specific target therapy but biological agents combined with chemotherapy may be effective. To assess the role of biological agents in metastatic triple-negative breast cancer we performed a systematic review of phase III randomized controlled trials published from January 2006 to February 2013 and presentations at ESMO, ASCO, and SABCS congresses in 2010-2012. We consulted PubMed and ClinicalTrials.gov. Only studies comparing biological agents and chemotherapy versus chemotherapy alone were considered. Relevant statistical variables were log of the hazard ratio and relative variance for progression-free survival (PFS) and overall survival (OS). Of 353 PubMed publications and 229 studies registered on ClinicalTrials.gov, 10 trials were selected and 5293 patients were analyzed: 1546 had mTNBC. Biological agents considered were bevacizumab, sunitinib, sorafenib, lapatinib, iniparib and cetuximab. In addition, a meta analysis of the four studies containing bevacizumab was performed and it showed a PFS improvement with a relative risk reduction of 35% (95% CI: 25-43%). No effect on OS was observed. No PFS and OS benefit was detected with the other agents. No improvement of OS was detected in patients treated with biological agents plus chemotherapy, while a significant PFS improvement was observed only for bevacizumab and cetuximab. The overall impact of these agents on patient survival was not as great as expected, probably because the molecular basis of this illness needs to be better understood so that treatment can be more appropriately tailored.

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.

Patients with metastatic ovarian cancer continue to experience high recurrence rates and significant morbidity from standard treatments. There is a great need for efficacious tumor-specific agents in ovarian cancer. Iniparib (BSI-201) is a targeted drug currently under investigation.The authors identified the mechanistic and clinical data available on the role of iniparib in ovarian cancer. Iniparib was initially thought to act via the poly-ADP ribose polymerase 1 (PARP-1) pathway, but recent studies have shown only nonspecific interactions between the drug and PARP proteins. Although iniparib is only active in cancer cells, the exact mechanism of action remains unclear. Iniparib was well tolerated at all dose levels in Phase I studies of solid organ malignancies. Preliminary data from Phase II studies of iniparib for the treatment of platinum-sensitive and platinum-resistant recurrent ovarian cancer show improvement in survival compared to historic controls. There are currently no Phase III studies.Iniparib shows promise in early clinical trials; however, understanding the pathways of cytotoxicity will be crucial as cancer therapy becomes increasingly individualized.

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.

Development of iniparib as an anti-cancer agent was hindered in part by lingering questions regarding its mechanism of action, the activity of its metabolites, and their potential accumulation in tumors. Due to strong similarities in metabolism of iniparib between humans and dogs, a veterinary clinical trial in pet dogs with spontaneous cancers was designed to answer specific questions pertaining to pharmacokinetic exposures and tolerability of iniparib. Dogs were treated with iniparib alone and in combination with carboplatin chemotherapy. Iniparib doses ranged between 10-70 mg/kg intravenously (IV). Plasma, tumor and normal tissue samples were collected before and at various time points scheduled after exposure for pharmacokinetic and biologic analysis. The primary endpoints included characterization of dose-limiting toxicities (DLT) and determination of the drug exposures that could be achieved in both normal and tumor tissues. Nineteen dogs were treated. DLT included fever, anorexia, diarrhea, neutropenia, and thrombocytopenia; most effects were attributable to carboplatin based on the timing of adverse event onset. The maximum tolerated dose (MTD) of iniparib was not identified. Moderate to high variability in plasma exposure was noted for iniparib and all metabolites between animals. When quantifiable, iniparib and metabolite plasma:tumor ratios were < 0.088 and

Poly(ADP-ribose) polymerase (PARP) inhibitors can generate synthetic lethality in cancer cells defective in homologous recombination. However, the mechanism(s) by which they affect DNA repair has not been established. Here we directly determined the effects of PARP inhibition and PARP1 depletion on the repair of ionizing radiation-induced single- and double-strand breaks (SSBs and DSBs) in human lymphoid cell lines. To do this, we developed an in vivo repair assay based on large endogenous Epstein–Barr virus (EBV) circular episomes. The EBV break assay provides the opportunity to assess quantitatively and simultaneously the induction and repair of SSBs and DSBs in human cells. Repair was efficient in G1 and G2 cells and was not dependent on functional p53. shRNA-mediated knockdown of PARP1 demonstrated that the PARP1 protein was not essential for SSB repair. Among 10 widely used PARP inhibitors, none affected DSB repair, although an inhibitor of DNA-dependent protein kinase was highly effective at reducing DSB repair. Only Olaparib and Iniparib, which are in clinical cancer therapy trials, as well as 4-AN inhibited SSB repair. However, a decrease in PARP1 expression reversed the ability of Iniparib to reduce SSB repair. Because Iniparib disrupts PARP1–DNA binding, the mechanism of inhibition does not appear to involve trapping PARP at SSBs.

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.

Summary Background Olaparib (AZD2281) is a small-molecule, potent oral poly(ADP-ribose) polymerase (PARP) inhibitor. We aimed to assess the safety and tolerability of this drug in patients without BRCA1 or BRCA2 mutations with advanced triple-negative breast cancer or high-grade serous and/or undifferentiated ovarian cancer. Methods In this phase 2, multicentre, open-label, non-randomised study, women with advanced high-grade serous and/or undifferentiated ovarian carcinoma or triple-negative breast cancer were enrolled and received olaparib 400 mg twice a day. Patients were stratified according to whether they had a BRCA1 or BRCA2 mutation or not. The primary endpoint was objective response rate by Response Evaluation Criteria In Solid Tumors (RECIST). All patients who received treatment were included in the analysis of toxic effects, and patients who had measurable lesions at baseline were included in the primary efficacy analysis. This trial is registered at ClinicalTrials.gov, number NCT00679783. Findings 91 patients were enrolled (65 with ovarian cancer and 26 breast cancer) and 90 were treated between July 8, 2008, and Sept 24, 2009. In the ovarian cancer cohorts, 64 patients received treatment. 63 patients had target lesions and therefore were evaluable for objective response as per RECIST. In these patients, confirmed objective responses were seen in seven (41%; 95% CI 22–64) of 17 patients with BRCA1 or BRCA2 mutations and 11 (24%; 14–38) of 46 without mutations. No confirmed objective responses were reported in patients with breast cancer. The most common adverse events were fatigue (45 [70%] of patients with ovarian cancer, 13 [50%] of patients with breast cancer), nausea (42 [66%] and 16 [62%]), vomiting (25 [39%] and nine [35%]), and decreased appetite (23 [36%] and seven [27%]). Interpretation Our study suggests that olaparib is a promising treatment for women with ovarian cancer and further assessment of the drug in clinical trials is needed. Funding AstraZeneca.

Poly (ADP-ribose) polymerase (PARP) is a novel therapeutic target in cancer. Preclinical studies demonstrate that PARP inhibitors selectively kill BRCA-deficient cells and potentiate the effects of DNA-damaging agents. There are several PARP inhibitors in clinical development, including olaparib, iniparib, veliparib, PF-01367338, and MK-4827. Phase II studies of single-agent olaparib demonstrate activity in BRCA-associated cancers. A randomized phase II trial showed that the addition of iniparib to gemcitabine and carboplatin in patients with metastatic triple-negative breast cancer (TNBC) improved progression-free survival and overall survival. A phase III trial evaluating this combination in metastatic TNBC has completed accrual. Phase III studies of olaparib in BRCA-associated breast cancer and veliparib in breast cancer are being planned. This article reviews the clinical studies to date that have evaluated PARP inhibitors as a single agent or in combination with chemotherapy in patients with breast cancer, including BRCA-associated breast cancer and TNBC.

Triple-negative breast cancers have inherent defects in DNA repair, making this cancer a rational target for therapy based on poly(adenosine diphosphate-ribose) polymerase (PARP) inhibition.We conducted an open-label, phase 2 study to compare the efficacy and safety of gemcitabine and carboplatin with or without iniparib, a small molecule with PARP-inhibitory activity, in patients with metastatic triple-negative breast cancer. A total of 123 patients were randomly assigned to receive gemcitabine (1000 mg per square meter of body-surface area) and carboplatin (at a dose equivalent to an area under the concentration-time curve of 2) on days 1 and 8--with or without iniparib (at a dose of 5.6 mg per kilogram of body weight) on days 1, 4, 8, and 11--every 21 days. Primary end points were the rate of clinical benefit (i.e., the rate of objective response [complete or partial response] plus the rate of stable disease for ≥6 months) and safety. Additional end points included the rate of objective response, progression-free survival, and overall survival.The addition of iniparib to gemcitabine and carboplatin improved the rate of clinical benefit from 34% to 56% (P=0.01) and the rate of overall response from 32% to 52% (P=0.02). The addition of iniparib also prolonged the median progression-free survival from 3.6 months to 5.9 months (hazard ratio for progression, 0.59; P=0.01) and the median overall survival from 7.7 months to 12.3 months (hazard ratio for death, 0.57; P=0.01). The most frequent grade 3 or 4 adverse events in either treatment group included neutropenia, thrombocytopenia, anemia, fatigue or asthenia, leukopenia, and increased alanine aminotransferase level. No significant difference was seen between the two groups in the rate of adverse events.The addition of iniparib to chemotherapy improved the clinical benefit and survival of patients with metastatic triple-negative breast cancer without significantly increased toxic effects. On the basis of these results, a phase 3 trial adequately powered to evaluate overall survival and progression-free survival is being conducted. (Funded by BiPar Sciences [now owned by Sanofi-Aventis]; ClinicalTrials.gov number, NCT00540358.).

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.

Summary Background 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. Methods Women (aged ≥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. Findings 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%]). Interpretation 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. Funding AstraZeneca.

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.

Objective The aim of the study was to evaluate the activity and tolerability of iniparib monotherapy in women with BRCA1 or BRCA2-associated advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer. Methods and Materials Eligible patients had advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer, germline BRCA1 or BRCA2 mutation, measurable disease, and at least 1 previous treatment regimen of platinum/taxane chemotherapy. Patients received iniparib 8 mg/kg intravenously on days 1 and 4 weekly, with imaging every 8 weeks. Treatment continued until disease progression or adverse events (AEs) prohibited further therapy. Common Terminology Criteria for AEs v3.0 was used to grade AEs. The primary endpoint was tumor response. The study was conducted with a Simon 2-stage design with 12 and 23 patients planned in the first and second stage, respectively. The study was designed to distinguish between 10% and 30% responding with types 1 and 2 error of 0.10. Results Twelve patients were treated on study, with median exposure to iniparib of 7.5 weeks. The median number of previous chemotherapeutic regimens was 7. Treatment-related AEs (≥10%) included asthenia (83.3%), constipation (25%), diarrhea (25%), nausea (25%), abdominal pain (16.7%), and decreased hemoglobin (16.7%). All treatment-related AEs were grades 1 or 2 with the following 2 exceptions: 1 grade 3 diarrhea and 1 grade 3 hypertension. One patient had stable disease lasting 2 cycles; the remaining 11 patients had progressive disease. The study did not proceed to second stage enrollment. Conclusions Iniparib did not show significant activity in this heavily pretreated ovarian cancer population, all of whom had BRCA1 or BRCA2 mutations.

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.

Germline mutations in the BRCA1, BRCA2 and Fanconi anaemia genes confer cancer susceptibility, and the proteins encoded by these genes have distinct functions in related DNA-repair processes. Emerging evidence indicates that these processes are disrupted by numerous mechanisms in sporadic cancers. Collectively, there are properties that define 'BRCAness' — that is, traits that some sporadic cancers share with those occurring in either BRCA1- or BRCA2-mutation carriers. These common properties might have important implications for the clinical management of these cancers.