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Longitudinal studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine-induced immune responses in patients with cancer are needed to optimize clinical care. In a prospective cohort study of 366 (291 vaccinated) patients, we measured antibody levels [anti-spike (IgG-(S-RBD) and anti-nucleocapsid immunoglobulin] at three time points. Antibody level trajectories and frequency of breakthrough infections were evaluated by tumor type and timing of treatment relative to vaccination. IgG-(S-RBD) at peak response (median = 42 days after dose 2) was higher (P = 0.002) and remained higher after 4 to 6 months (P = 0.003) in patients receiving mRNA-1273 compared with BNT162b2. Patients with solid tumors attained higher peak levels (P = 0.001) and sustained levels after 4 to 6 months (P < 0.001) compared with those with hematologic malignancies. B-cell targeted treatment reduced peak (P = 0.001) and sustained antibody responses (P = 0.003). Solid tumor patients receiving immune checkpoint inhibitors before vaccination had lower sustained antibody levels than those who received treatment after vaccination (P = 0.043). Two (0.69%) vaccinated and one (1.9%) unvaccinated patient had severe COVID-19 illness during follow-up. Our study shows variation in sustained antibody responses across cancer populations receiving various therapeutic modalities, with important implications for vaccine booster timing and patient selection.Significance:Long-term studies of immunogenicity of SARS-CoV-2 vaccines in patients with cancer are needed to inform evidence-based guidelines for booster vaccinations and to tailor sequence and timing of vaccinations to elicit improved humoral responses.

Supplementary Data

Application of immunotherapy has revolutionized treatment of number of malignancies. We present a review of immunotherapy approaches, early-phase data of number of new immunotherapeutic targets in melanoma, cutaneous squamous cell carcinoma, Merkel cell cancer, and non-small cell lung cancer.

Longitudinal studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine-induced immune responses in patients with cancer are needed to optimize clinical care. In a prospective cohort study of 366 (291 vaccinated) patients, we measured antibody levels [anti-spike (IgG-(S-RBD) and anti-nucleocapsid immunoglobulin] at three time points. Antibody level trajectories and frequency of breakthrough infections were evaluated by tumor type and timing of treatment relative to vaccination. IgG-(S-RBD) at peak response (median = 42 days after dose 2) was higher (P = 0.002) and remained higher after 4 to 6 months (P = 0.003) in patients receiving mRNA-1273 compared with BNT162b2. Patients with solid tumors attained higher peak levels (P = 0.001) and sustained levels after 4 to 6 months (P < 0.001) compared with those with hematologic malignancies. B-cell targeted treatment reduced peak (P = 0.001) and sustained antibody responses (P = 0.003). Solid tumor patients receiving immune checkpoint inhibitors before vaccination had lower sustained antibody levels than those who received treatment after vaccination (P = 0.043). Two (0.69%) vaccinated and one (1.9%) unvaccinated patient had severe COVID-19 illness during follow-up. Our study shows variation in sustained antibody responses across cancer populations receiving various therapeutic modalities, with important implications for vaccine booster timing and patient selection. Significance: Long-term studies of immunogenicity of SARS-CoV-2 vaccines in patients with cancer are needed to inform evidence-based guidelines for booster vaccinations and to tailor sequence and timing of vaccinations to elicit improved humoral responses.

Background: Eflapegrastim (Rolontis®, Efla) represents the first novel, long-acting granulocyte-colony stimulating factor (G-CSF) to be introduced in more than 15 years. Efla consists of a recombinant human G-CSF analog conjugated to a human IgG4 Fc fragment via a polyethylene glycol linker. Preclinical, clinical, and pharmacodynamic/pharmacokinetic data have shown increased potency for Efla versus pegfilgrastim (Peg). Both independent, randomized Phase 3 studies comparing Efla and Peg for prophylaxis of chemotherapy-induced neutropenia in patients with early-stage breast cancer (ESBC) met the primary endpoint of non-inferiority in duration of severe neutropenia (SN; ANC75kg. The safety profiles, including AEs and discontinuations, for Efla and Peg were comparable, and >99% of all patients received full dose of TC on schedule. The majority (67%) of patients with SN experienced a 1 day duration, occurring between Days 7 and 8 after TC. Mean duration of SN for Efla was statistically lower than for Peg (0.24 vs. 0.36 days; p=0.029). The above statistical significance was maintained for Efla after adjusting for demographic and baseline characteristics, namely age, weight, enrolling geographical region, and treatment setting in a multivariate model. Similarly, the incidence of SN for Efla was statistically lower than Peg in Cycle 1 (17.5% vs 24%; relative risk reduction [RRR]=27%; p=0.043). Univariate analysis of the incidence of SN showed a significant risk reduction in favor of Efla (8.6% vs 14.1%; p=0.034) for patients weighing >75kg (p=0.034). Multivariate analysis of SN showed significant odds ratio of SN for age ≥65 years and baseline ANC >6 × 109/L in favor of Efla (OR=0.42 and 0.39, respectively). The incidence of SN in Cycles 2-4 was comparable between treatment groups. Also, the incidence of febrile neutropenia and neutropenic complications was similar with 75kg. Eflapegrastim is a novel, long-acting and potent recombinant human G-CSF which may provide an attractive option in supporting patients at risk for SN-related complications. Citation Format: Lee S Schwartzberg, Gajanan Bhat, Alvaro Restrepo, Osama Hlalah, Inderjit Mehmi, Yong Wha Moon, Seungjae Baek, Shanta Chawla, Francois Lebel, Patrick Wayne Cobb. Pooled efficacy analysis from two phase 3 studies in patients receiving eflapegrastim, a novel, long-acting granulocyte-colony stimulating factor, following TC for early-stage breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS9-59.

Background Eflapegrastim, a novel, long‐acting recombinant human granulocyte‐colony stimulating factor (rhG‐CSF), consists of a rhG‐CSF analog conjugated to a human IgG4 Fc fragment via a short polyethylene glycol linker. Preclinical and phase I and II pharmacodynamic and pharmacokinetic data showed increased potency for neutrophil counts for eflapegrastim versus pegfilgrastim. This open‐label phase III trial compared the efficacy and safety of eflapegrastim with pegfilgrastim for reducing the risk of chemotherapy‐induced neutropenia. Materials and Methods Patients with early‐stage breast cancer were randomized 1:1 to fixed‐dose eflapegrastim 13.2 mg (3.6 mg G‐CSF) or standard pegfilgrastim (6 mg G‐CSF) following standard docetaxel plus cyclophosphamide chemotherapy for 4 cycles. The primary objective was to demonstrate the noninferiority of eflapegrastim compared with pegfilgrastim in mean duration of severe neutropenia (DSN; grade 4) in cycle 1. Results Eligible patients were randomized 1:1 to study arms (eflapegrastim, n = 196; pegfilgrastim, n = 210). The incidence of cycle 1 severe neutropenia was 16% (n = 31) for eflapegrastim versus 24% (n = 51) for pegfilgrastim, reducing the relative risk by 35% (p = .034). The difference in mean cycle 1 DSN (−0.148 day) met the primary endpoint of noninferiority (p < .0001) and also showed statistical superiority for eflapegrastim (p = .013). Noninferiority was maintained for the duration of treatment (all cycles, p < .0001), and secondary efficacy endpoints and safety results were also comparable for study arms. Conclusion These results demonstrate noninferiority and comparable safety for eflapegrastim at a lower G‐CSF dose versus pegfilgrastim. The potential for increased potency of eflapegrastim to deliver improved clinical benefit warrants further clinical study in patients at higher risk for CIN. Implications for Practice Chemotherapy‐induced neutropenia (CIN) remains a significant clinical dilemma for oncology patients who are striving to complete their prescribed chemotherapy regimen. In a randomized, phase III trial comparing eflapegrastim to pegfilgrastim in the prevention of CIN, the efficacy of eflapegrastim was noninferior to pegfilgrastim and had comparable safety. Nevertheless, the risk of CIN remains a great concern for patients undergoing chemotherapy, as the condition frequently results in chemotherapy delays, dose reductions, and treatment discontinuations., Myelosuppression, particularly neutropenia, has presented a major challenge in cancer treatment since the introduction of cytotoxic chemotherapy. This article reports the results of a phase III trial that compared the efficacy and safety of eflapegrastim with pegfilgrastim for reducing the risk of chemotherapy‐induced neutropenia.

Background: Eflapegrastim (E) represents the first myeloid growth factor innovation in more than 15 years. A novel, long-acting recombinant human granulocyte-colony stimulating factor (rhG-CSF), E consists of a rhG-CSF analog conjugated to a human IgG4 Fc fragment via a polyethylene glycol linker. Preclinical and Phase I and II pharmacodynamic and pharmacokinetic data showed increased potency for E versus pegfilgrastim (P). Two independent randomized Phase III trials comparing fixed dose E and P (E 3.6 mg G-CSF and P 6.0 mg G-CSF) for the management of chemotherapy-induced neutropenia (CIN) have recently been completed. Both trials met the primary endpoint of non-inferiority for E vs P in Cycle 1 duration of severe neutropenia (P Patients and Methods: Patients with early-stage breast cancer (ESBC) who were candidates for adjuvant or neoadjuvant chemotherapy were randomized 1:1 in two open-label Phase III trials to E 13.2 mg (3.6 mg G-CSF) or standard P (6 mg G-CSF) administered on Day 2 following TC (docetaxel/cyclophosphamide) chemotherapy on Day 1 of each of 4 cycles. Blood for CBC and serum chemistry was collected in every cycle. Safety assessments began with the first dose of TC and continued for one year after the last dose of study drug. AEs and laboratory values were graded according to NCI CTCAE version 4.03. Immunogenicity was assessed from blood samples collected on Day 1 of each cycle, at the end-of-treatment visit, and at 6- and 12-month follow-up visits. Results: A total of 660 patients who received at least one dose of eflapegrastim (n=334) or pegfilgrastim (n=326) were included in this integrated safety analysis. The two treatment groups were well balanced for demographics and baseline disease characteristics. The mean age was 59y, ~40% were aged >65y, ~54% weighed >75kg, and ~80% were treated in the adjuvant setting. Median relative dose intensity for T and C was >99% for both groups. A similar percentage of patients in both treatment groups discontinued treatment due to AEs (4% E vs 6% P), with 2% in each group discontinuing due to AEs related to E or P. Serious AEs were similar in both groups (15% each). Incidence of AEs irrespective of causality were also similar between groups (74% E vs. 72% P). No notable differences between groups were observed in the types of study-drug-related AEs. The majority of study-drug-related AEs occurred with an incidence ≤10% for both E and P. As expected with myeloid growth factors, study-drug-related AEs occurring in >10% in either group were bone pain (E vs P: 33% vs 34%), arthralgia (15% vs 10%), back pain (14% vs 9%), myalgia (14% vs 9%), and headache (11% vs 8%). Incidence of febrile neutropenia and neutropenic complications were similar and less than 5% in each treatment group. No leukocytosis, splenic rupture, or anaphylaxis was reported in any patient receiving E or P. The overall incidence of immunogenicity was similar in both groups and there was no demonstrable impact on clinical safety or efficacy. Conclusions: Two large, randomized Phase III trials (Total n=660) of E vs P administered once-per-cycle showed E at a lower G-CSF dose to be safe and effective for the prophylaxis of CIN in patients with ESBC receiving TC chemotherapy. E is a novel long-acting rhG-CSF with increased potency and similar toxicity to P and may provide an attractive alternative for growth factor support of patients at high risk for CIN-related complications. Citation Format: Lee S Schwartzberg, Gajanan Bhat, Julio Peguero, Richy Agajanian, Jayaram Bharadwaj, Alvaro Restrepo, Osama Hlalah, Inderjit Mehmi, Shanta Chawla, Francois Lebel, Patrick W Cobb. Eflapegrastim, a novel long-acting granulocyte-colony stimulating factor: Integrated safety results in patients with early-stage breast cancer treated with TC chemotherapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-12.

Background: The phase 1/2 KEYMAKER-U02 substudy 02C (NCT04303169) is evaluating neoadjuvant pembro + investigational agents or pembro alone followed by adjuvant pembro in stage IIIB-D melanoma. Results from patients treated with neoadjuvant pembro (anti-PD-1) + vibo (anti-TIGIT; arm 1), pembro + geba (coxsackievirus A21; arm 2), or pembro alone (arm 3) are presented. Methods: Eligible patients were ≥18 y with resectable stage IIIB, IIIC, or IIID melanoma per AJCC 8th ed criteria, ≥1 measurable lesion per RECIST v1.1, and ECOG PS ≤1. Patients were randomly allocated across open investigational arms. Before resection, patients in arm 1 received 2 administrations of pembro 200 mg Q3W + vibo 200 mg Q3W (cycle 1, day 1; cycle 2, day 1); patients in arm 2 received 1 administration of pembro 400 mg (cycle 1, day 8) + 5 administrations of geba at a fixed dose of 3 × 108 tissue culture infectious dose 50% during cycle 1 (days 1, 3, 5, 8, and 22); and patients in arm 3 received 1 administration of pembro 400 mg. Surgical resection was performed at week 6. At week 12, patients started adjuvant pembro 400 mg Q6W for ≤8 administrations (total treatment duration, ~1 y). Primary end points were safety and tolerability and pCR rate by central review. Secondary end points were near pCR rate and pPR rate by central review and RFS by investigator review. ORR per RECIST v1.1 and EFS by investigator review were exploratory. Results: At data cutoff (September 9, 2022), 66 patients had been assigned to treatment (arm 1 [pembro + vibo], n = 26; arm 2 [pembro + geba], n = 25; arm 3 [pembro alone], n = 15). Median follow-up was 14.1 mo (range, 8.0-26.1). Treatment-related AEs occurred in 92% of patients in arm 1, 84% in arm 2, and 80% in arm 3. Grade 3/4 treatment-related AEs occurred in 8%, 24%, and 7% of patients, respectively, with no grade 5 treatment-related AEs. 3 patients (12%) in arm 1, 5 (20%) in arm 2, and 0 in arm 3 discontinued any drug because of treatment-related AEs. Immune-mediated AEs or infusion reactions were reported in 31% of patients in arm 1, 32% in arm 2, and 27% in arm 3. The pCR rate was 38% (95% CI, 20-59) in arm 1, 28% (12-49) in arm 2, and 40% (16-68) in arm 3; the near pCR rate was 12% (2-30), 12% (3-31), and 7% ( Conclusions: Neoadjuvant pembro + vibo, pembro + geba, and pembro alone followed by adjuvant pembro had manageable safety and promising antitumor activity in patients with stage IIIB-D melanoma. Of the combination treatments, pembro + vibo showed the most promise. Citation Format: Reinhard Dummer, Caroline Robert, Richard A. Scolyer, Janis M. Taube, Michael T. Tetzlaff, Andrew Hill, Jean-Jacques Grob, David C. Portnoy, Celeste Lebbe, Muhammad A. Khattak, Jonathan Cohen, Gil Bar-Sela, Inderjit Mehmi, Ronnie Shapira Frommer, Nicolas Meyer, Yixin Ren, Mizuho Fukunaga-Kalabis, Clemens Krepler, Georgina V. Long. KEYMAKER-U02 substudy 02C: neoadjuvant pembrolizumab (pembro) + vibostolimab (vibo) or gebasaxturev (geba) or pembro alone followed by adjuvant pembro for stage IIIB-D melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT002.

Background: TAPUR is a phase II basket study evaluating antitumor activity of commercially available targeted agents in pts with advanced cancers with specific genomic alterations. Results in a cohort of pts with solid tumors and MET amp or mut treated with C are reported. Methods: Eligible pts had no standard treatment (tx) options, had measurable disease, ECOG performance status (PS) 0-2, and adequate organ function. Pts with non-small cell lung cancer were excluded. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. Pts received C at 250 mg orally BID until disease progression. Low accruing histology-specific cohorts with MET amp or mut were collapsed into 1 histology-pooled cohort for analysis. Primary end point was disease control (DC) per investigator, defined as complete or partial response (PR) or stable disease (SD) of at least 16+ weeks (wks) duration (SD16+) per RECIST v1.1. The primary end point was summarized as a proportion and the hypothesized null DC rate of 15% was evaluated by a 1-sided exact binomial test with α= 0.10. Other end points were progression-free survival (PFS), overall survival (OS), duration of response and SD, and safety. Results: 31 pts with solid tumors (12 tumor types) and MET mut only (n=10), amp only (n=19), or mut and amp (n=1) were enrolled; 1 pt with overexpression was ineligible. 3 additional pts were unevaluable for efficacy. Table shows demographics and outcomes. 2 PR (both esophageal adenocarcinoma with MET amp) and 4 SD16+ (2 renal cell carcinoma, 1 with mut, 1 with amp; colorectal with amp; small intestine with amp) were observed for DC rate of 21% (1-sided 90% CI: 12%, 100%) and objective response rate of 7% (95% CI: 1%, 24%). The null DC rate was not rejected. 5 pts had ≥1 grade 3 tx-related adverse or serious adverse event. Conclusions: C did not meet prespecified criteria to declare a signal of activity in pts with solid tumors with MET amp or mut. Table: Baseline Characteristics (N=31); Efficacy Outcomes (n=28); Toxicity Outcomes (N=31) Median (Med) age, years (range) 61 (30, 82) Female, % 16 (52) ECOG PS, % 0 15 (48) 1 12 (39) 2 4 (13) Prior systemic regimens, % 1 3 (10) 2 5 (16) ≥3 23 (74) DC rate, % (OR and SD16+) (1-sided 90% CI) 21 (12, 100) Objective response rate, % (95% CI) 7 (1, 24) Med PFS, wks (95% CI) 8 (8, 13) Med OS, wks (95% CI) 37 (26, 68) Duration of response, wks (n=2) 14 and 20 Med duration SD, wks (n=4) 27 (26, 28) Number of pts1 with tx-related grade 3 adverse or any grade serious adverse event AE2 5 (16) SAE3 3 (10) 1Pts may have experienced one or more events 2ALT increase, diarrhea and all SAEs 3Acute kidney injury, ALT increase, AST increase, blood bilirubin increase, creatinine increase, dehydration, fatigue, GGT increase, hyperkalemia, nausea, sinus bradycardia Citation Format: Kathryn F. Mileham, Michael Rothe, Pam K. Mangat, Elizabeth Garrett-Mayer, Herbert L. Duvivier, Carmen J. Calfa, Carrie L. Dul, Alissa S. Marr, Eugene R. Ahn, Deepti Behl, Michael J. Hall, Inderjit Mehmi, Anu Gaba, Rom Leidner, Mark M. Zalupski, Gina N. Grantham, Abigail Gregory, Susan Halabi, Richard L. Schilsky. Crizotinib (C) in patients (pts) with solid tumors with MET amplification (amp) or mutation (mut): Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT226.

Background: MEDI1191 is an IT-administered lipid nanoparticle-formulated mRNA encoding IL-12. This phase 1, open-label study (NCT03946800) showed that MEDI1191 in sequential (seq) or concurrent (conc) combination with IV D (anti-PD-L1) was safe and had preliminary antitumor activity in pts with advanced/metastatic solid tumors who had progressed on SoC. Here we present updated analyses, including the first report of pts with deep-seated lesions. Methods: In Part 1A (subcutaneous/cutaneous [SC/C] lesions), pts received MEDI1191 on Days 1 and 22, followed by D 1500 mg on Day 43 then Q4W. In Parts 1B (SC/C) and 1D (deep-seated lesions), pts received MEDI1191 on Days 1, 29 and 57 then Q8W, with D on Day 1 then Q4W. Treatment continued for up to 2 years, until progression or unacceptable toxicity. Primary objectives were safety, tolerability and maximum tolerated dose (MTD); secondary objectives included preliminary antitumor activity per RECIST v1.1 in injected/non-injected lesions. Results: As of October 5, 2022, 61 pts (40 had prior anti-PD-[L]1) received seq (Part 1A 0.1-12.0 μg, n=25 [4/25 had MEDI1191 only]) or conc (Part 1B 1.0-12.0 μg, n=27; Part 1D 1.0-3.0 μg, n=9) MEDI1191 + D. The most commonly represented cancer was melanoma (n=14). Pts in Part 1D had pancreatic (n=2), colorectal (n=2), gastric, anal, melanoma, neuroendocrine or unknown primary cancer (each n=1); all had hepatic metastases. There were no dose-limiting toxicities for MEDI1191 and no MTD was identified. Gr ≥3 MEDI1191-related AEs occurred in 3 pts (4.9%; Gr 3 asthenia and pyrexia, each n=1; Gr 4 lymphocyte count decreased, n=1); 2 pts (3.3%) had a MEDI1191-related serious AE (SAE; Gr 2 pyrexia and confusion, each n=1). Gr ≥3 D-related AEs occurred in 3 pts (4.9%; Gr 3 asthenia, pyrexia [both also MEDI1191-related] and pruritus; each n=1); 1 pt (1.6%) had a D- and MEDI1191-related SAE (Gr 2 pyrexia). In Parts 1A and 1B, 7 pts had partial responses (PRs): 5 confirmed (cPRs) in melanoma (n=2), sarcoma, breast and neuroendocrine cancer (each n=1), and 2 unconfirmed (uPRs) in melanoma and head and neck cancer (each n=1); no pts had PRs in Part 1D. 3/5 pts with cPR had prior anti-PD-(L)1; 2/3 also had prior anti-CTLA-4. For the 5 cPRs, DoR was 1.9-22.3 months (median not reached); 3 had ongoing PRs and 2 had stable disease (SD) at data cutoff. Non-target injected lesions shrank in 4 pts with cPRs. Overall, 15 pts had SD (including the 2 uPRs). MEDI1191 induced pharmacodynamic changes in the periphery and tumor microenvironment. A ≥2-fold increase in serum IL-12 levels was seen in 42/46 pts, with increases in serum IFNγ in 37/46; 9/22 pts had ≥2-fold increases in CD8+ T cell tumor infiltration and tumoral PD-L1 expression. Conclusions: MEDI1191 + D was safe and tolerable in pts with SC/C or deep-seated lesions. Antitumor activity was seen in injected and distant lesions, and pharmacodynamic activity was consistent with expectations based on mechanistic biology. Citation Format: Eduardo Castañón, Dmitriy Zamarin, Benedito A. Carneiro, Thomas Marron, Sandip Pravin Patel, Vivek Subbiah, Inderjit Mehmi, Honey Kumar Oberoi, Anthony El-Khoueiry, Benjamin Ridgway, Nairouz Elgeioushi, Nicholas M. Durham, Emily Jennings, Michael Abadier, Paula G. Fraenkel, Analia Azaro, Omid Hamid. Intratumoral (IT) MEDI1191 + durvalumab (D): Update on the first-in-human study in advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT004.

BackgroundThere are limited therapeutic options for patients with progressive disease (PD) on or after PD-1–blocking antibody therapy. Vidutolimod (CMP-001) is a first-in-class, immunostimulatory virus-like particle containing a CpG-A Toll-like receptor 9 (TLR9) agonist. This phase 1b study evaluated the safety and clinical activity of intratumoral vidutolimod with and without pembrolizumab in patients with refractory melanoma.MethodsThis two-part, open-label, multicenter, phase 1b study (NCT02680184) enrolled adults with histologically confirmed metastatic or unresectable cutaneous melanoma who had stable disease after ≥12 weeks or PD on anti−PD-1 treatment, measurable disease per RECIST v1.1, ECOG PS 0/1, and ≥1 lesion accessible for intratumoral injection. Part 1 evaluated vidutolimod + pembrolizumab and Part 2 evaluated vidutolimod monotherapy. Key objectives included assessment of safety and clinical activity, and exploratory analyses were performed on available tumor biopsies using immunohistochemistry and RNAseq.ResultsAt data cutoff (August 17, 2021), 159 patients had enrolled in Part 1 and 40 patients in Part 2. The median age was 64 years in Part 1 (range, 30-90) and 68 years in Part 2 (range, 30-89). Most patients had PD as their last response to prior anti–PD-1 therapy (Part 1, 93.1%; Part 2, 80.0%). Grade 3/4 treatment-related adverse events (TRAEs) occurred in 37.1% of patients treated with vidutolimod + pembrolizumab and in 22.5% of patients treated with vidutolimod monotherapy. No treatment-related deaths occurred. Based on the efficacy data presented in Table 1, vidutolimod polysorbate 20 (PS20) A was selected for further development as this formulation in combination with pembrolizumab had a best objective response rate (ORR; RECIST v1.1) of 23.5%, with a median duration of response (DOR) of 25.2 months. Vidutolimod monotherapy had an ORR of 20.0%, with a median DOR of 5.6 months. Exploratory translational analyses identified association of unique biomarkers with response among patients with T cell–inflamed versus non-T cell–inflamed tumors at baseline.Abstract 950 Table 1Safety and clinical activity of vidutolomod ± pembrolizumabConclusionsPromising clinical activity was observed with vidutolimod + pembrolizumab and vidutolimod monotherapy in patients with PD-1 blockade–refractory melanoma. A manageable safety profile was observed. The DOR with vidutolimod + pembrolizumab was substantially longer than with vidutolimod monotherapy. Clinical studies to confirm the efficacy of vidutolimod + PD-1 blockade in patients with previously untreated unresectable/metastatic melanoma (phase 2/3, NCT04695977) or PD-1 blockade–refractory melanoma (phase 2, NCT04698187) are ongoing.AcknowledgementsThis work was supported by Checkmate Pharmaceuticals. Medical writing assistance was provided by Steffen Biechele, PhD (ApotheCom, San Francisco, CA, USA), and funded by Checkmate Pharmaceuticals.Trial RegistrationNCT02680184Ethics ApprovalThis study was approved by the WCG-WIRB; WIRB approval tracking number: 20152597.

Background: The ABC trials and the WSG Plan B trial demonstrated that certain early stage breast cancer patients can be appropriately treated with docetaxel and cyclophosphamide (TC) rather than doxorubicin and cyclophosphamide (AC); however both of these trials utilized six cycles of TC as the comparator. TC is given for 4 cycles based on the US Oncology 9735 trial. To our knowledge, there is no available data that has compared adverse events or outcomes of four versus six cycles of TC. Methods: This was a single-center, retrospective study evaluating recurrence-free survival, overall survival, and occurrence of toxicities between four and six cycles of docetaxel and cyclophosphamide adjuvant chemotherapy for early stage breast cancer at West Virginia University Cancer Institute. Results: 112 patients were included; 81 received four cycles and 31 received six. Recurrence free survival rates of patients that received four and six cycles of chemotherapy were 94% and 90%, respectively, at three years (P=0.68). Overall survival at three years was 99% versus 97% (P=0.49), respectively. The incidence of peripheral neuropathy requiring treatment was 42% in patients that received six cycles and 19% in patients that received four (P=0.015). Conclusion: The addition of two cycles of docetaxel and cyclophosphamide adjuvant chemotherapy for early stage breast cancer provides no additional recurrence-free or overall survival benefit but does increase the incidence of peripheral neuropathy requiring treatment. Table 1.Baseline Characteristics 4 Cycles (n=81)6 Cycles (n=31)P-valueAge, median years (range)57 (37-75)48 (32-71)0.001Receptor status, n (%) 0.63HR positive, HER2 negative61 (75)25 (81) Triple negative20 (25)6 (19) Cancer stage, n (%) 0.031I39 (48)9 (29) II39 (48)17 (55) III3 (4)5 (16) Lymph node involvement, n (%)24 (30)20 (65)0.001Ki67 (%), median (range)23 (2-99)23.5 (4-99)0.99Tumor grade, n (%) 0.07212 (2)4 (13) 242 (52)12 (39) 337 (46)15 (48) Surgery, n (%) Breast conservation35 (43)14 (45)0.99Unilateral mastectomy32 (40)9 (29)0.38Bilateral mastectomy14 (17)8 (26)0.43 Table 2.Adverse Events 4 Cycles (n=81)6 Cycles (n=31)P-valueDose reductions, n (%)17 (21)8 (26)0.62Dose delay, n (%)3 (4)1 (3)0.99Inpatient admissions, n (%)22 (27)8 (26)0.99Treatment for peripheral neuropathy, n (%)15 (19)13 (42)0.015 Citation Format: Mehmi I, Wight CE, Hill JL. Comparison of overall and recurrence-free survival between four and six cycles of adjuvant docetaxel and cyclophosphamide in early stage breast cancer [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 P1-13-10.

Simple Summary Overactivation of the human epidermal growth factor receptor 2 (HER2) is one of the main drivers of tamoxifen resistance in estrogen receptor (ER)-positive breast cancer patients. Combined targeting of HER2 and ER, however, has yielded disappointing results in the clinical setting. Therefore, other potential mechanisms for tamoxifen resistance would not be overcome by solely blocking the cross-talk between ER and HER2 at the receptor(s) level. Using cell lines, animal models, and clinical data, we provide evidence to support a critical role of fatty acid synthase (FASN)—the major site for endogenous fat synthesis—in HER2-driven tamoxifen resistance. Importantly, treatment with a FASN inhibitor impeded the estrogen-like tumor-promoting effects of tamoxifen and fully restored the anti-estrogenic activity of tamoxifen in ER+/HER2-overexpressing breast cancer xenografts. We postulate FASN as a biological determinant of HER2-driven tamoxifen resistance and FASN inhibition as a novel therapeutic approach to restore tamoxifen sensitivity in endocrine-resistant breast cancer. Abstract The identification of clinically important molecular mechanisms driving endocrine resistance is a priority in estrogen receptor-positive (ER+) breast cancer. Although both genomic and non-genomic cross-talk between the ER and growth factor receptors such as human epidermal growth factor receptor 2 (HER2) has frequently been associated with both experimental and clinical endocrine therapy resistance, combined targeting of ER and HER2 has failed to improve overall survival in endocrine non-responsive disease. Herein, we questioned the role of fatty acid synthase (FASN), a lipogenic enzyme linked to HER2-driven breast cancer aggressiveness, in the development and maintenance of hormone-independent growth and resistance to anti-estrogens in ER/HER2-positive (ER+/HER2+) breast cancer. The stimulatory effects of estradiol on FASN gene promoter activity and protein expression were blunted by anti-estrogens in endocrine-responsive breast cancer cells. Conversely, an AKT/MAPK-related constitutive hyperactivation of FASN gene promoter activity was unaltered in response to estradiol in non-endocrine responsive ER+/HER2+ breast cancer cells, and could be further enhanced by tamoxifen. Pharmacological blockade with structurally and mechanistically unrelated FASN inhibitors fully impeded the strong stimulatory activity of tamoxifen on the soft-agar colony forming capacity—an in vitro metric of tumorigenicity—of ER+/HER2+ breast cancer cells. In vivo treatment with a FASN inhibitor completely prevented the agonistic tumor-promoting activity of tamoxifen and fully restored its estrogen antagonist properties against ER/HER2-positive xenograft tumors in mice. Functional cancer proteomic data from The Cancer Proteome Atlas (TCPA) revealed that the ER+/HER2+ subtype was the highest FASN protein expressor compared to basal-like, HER2-enriched, and ER+/HER2-negative breast cancer groups. FASN is a biological determinant of HER2-driven endocrine resistance in ER+ breast cancer. Next-generation, clinical-grade FASN inhibitors may be therapeutically relevant to countering resistance to tamoxifen in FASN-overexpressing ER+/HER2+ breast carcinomas.

Background: IL-12 is a key mediator of antitumor immune response. In preclinical models, IT IL-12 mRNA led to IFNγ release and CD8+ T cell-dependent tumor regression and potentiated PD-L1 blockade. MEDI1191, a lipid nanoparticle-formulated mRNA encoding IL-12 delivered by IT injection, drives IL-12 production and enhances antitumor immune response with improved tolerability. We hypothesized that combining MEDI1191 with PD-L1 blockade would augment antitumor immunity in vivo. Here we report updated results from the dose-escalation phase of the first-in-human study of IT MEDI1191 and IV durvalumab (D; anti-PD-L1) for advanced/metastatic solid tumors (NCT03946800). Methods: In this multicenter, open-label study, MEDI1191 was dosed sequentially (seq, Part 1A) or concurrently (conc, Part 1B) with D. In Part 1A, MEDI1191 was given IT on Days 1 and 22 followed by D 1500 mg on day 43 and then Q4W IV. In Part 1B, MEDI1191 was given IT on Days 1, 29, 57 and then Q8W, along with D on Day 1 and then Q4W. Treatment continued until progression or unacceptable toxicity for up to 2 years. Eligible adult pts had any solid tumor with cutaneous or subcutaneous lesions suitable for IT injection and progression on standard therapy for recurrent/metastatic disease. Primary objectives were safety and tolerability and determination of maximum tolerated dose (MTD); secondary objectives included preliminary antitumor activity by RECIST v1.1. Results: Starting in May 2019, 31 pts received seq MEDI1191 with D (Part 1A cohorts 0.1-12 μg; n=20) or conc MEDI1191 with D (Part 1B cohorts 1.0-3.0 μg; n=11); 23 pts had received prior anti-PD-1/PD-L1 therapy. Most common tumor types were melanoma, n=8; head and neck cancer, n=4; and breast cancer, n=4. At the data cutoff of Dec 7, 2021, there were no dose-limiting toxicities and no MTD was identified. One pt (3.2%) had a Gr ≥3 MEDI1191-related AE (Gr 3 pyrexia, resolved within 24 hr) and 1 (3.2%) had a MEDI1191-related serious AE (SAE; Gr 2 confusion). Two pts had Gr 3 D-related AEs (6.5%, pyrexia also related to MEDI1191 and pruritus; each n=1); none had a D-related SAE. There were no Gr 4 related AEs. 3 pts had partial responses (PR): 1 with head and neck cancer (unconfirmed, off study) and 2 with anti-PD-1 resistant melanoma (1 confirmed, >12 months on treatment; 1 unconfirmed, off study); 10 pts had stable disease (including the 2 unconfirmed PRs). Among pts with available biomarker data (up to 3 μg in Part 1A and 1 μg in Part 1B), MEDI1191 increased serum IL-12 in 15/17 pts, increased CD8+ T cell tumor infiltration by >2-fold in 8/14 pts and increased tumor PD-L1 expression in 6/14 pts. Conclusions: IT MEDI1191 plus systemic anti-PD-L1 was safe and feasible. Preliminary antitumor efficacy and pharmacodynamics, including tumor CD8+ T cell recruitment, were consistent with expected mechanism of action. Pts with injectable deep visceral and superficial lesions are being recruited. Citation Format: Benedito A. Carneiro, Dmitriy Zamarin, Thomas Marron, Inderjit Mehmi, Sandip P. Patel, Vivek Subbiah, Anthony El-Khoueiry, David Grand, Kirema Garcia-Reyes, Sanjay Goel, Phillip Martin, Jixin Wang, Yuling Wu, Steven Eck, Benjamin Ridgway, Nairouz Elgeioushi, Jim Eyles, Nicholas Durham, Analia Azaro, Omid Hamid. First-in-human study of MEDI1191 (mRNA encoding IL-12) plus durvalumab in patients (pts) with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT183.

Background Therapeutic options are limited for patients with advanced melanoma that is refractory to PD-1 blockade. This study was performed in this patient population to assess the safety and antitumor activity of CMP-001, a CpG-A TLR9 agonist packaged within a virus-like particle. Methods Patients were eligible for this 2-part, open-label, multicenter, phase 1b study if they had metastatic/unresectable melanoma and stable disease after =12 weeks or progressive disease (PD) on/after anti-PD-1 therapy. Part 1 evaluated CMP-001 plus pembrolizumab dose-escalation and dose-expansion. Part 2 evaluated CMP-001 monotherapy. Accessible lesion(s) were injected intratumorally with CMP-001, at a polysorbate 20 (PS20) concentration of either 0.01% or 0.00167%. The Part 1 primary objective was to identify the recommended phase 2 dose (RP2D) and schedule of CMP-001 plus pembrolizumab, while the Part 2 primary objective was to assess the safety of CMP-001 monotherapy. Secondary objectives for both parts were a preliminary assessment of antitumor activity of CMP-001 plus pembrolizumab and CMP-001 monotherapy, and the overall safety profile and pharmacodynamics of the combination. Results In Part 1 (N=159) and Part 2 (N=40), 93.1% and 80.0% of patients had PD as their last response to prior anti–PD-1 therapy, respectively. The most common treatment-related adverse events (TRAEs; >25%) were flu-like symptoms (Parts 1 and 2) and injection-site reactions (Part 1). Grade 3/4 TRAEs were reported in 36.5% (Part 1) and 22.5% (Part 2) of patients, the most common being hypotension (Part 1: 6.9%; Part 2: 5.0%). No Grade 5 TRAEs were observed. In Part 1, the best objective response rate (ORR; RECIST v1.1) in patients treated with pembrolizumab and CMP-001 (PS20 0.01%) was 23.5% (23/98), while CMP-001 PS20 (0.00167%) resulted in a lower ORR of 11.5% (7/61). Seven additional patients had a delayed response after initial PD (table 1). The median duration of response was >1 year. In the 37 RECIST v1.1 and post-progression responders, the mean regression in injected and noninjected target lesions was 54.7% and 52.7%, respectively. In Part 2, the best ORR with CMP-001 monotherapy was 17.5% (7/40 patients); the response duration was shorter than in Part 1. Intratumoral CMP-001 PS20 0.01% 10 mg was selected as the RP2D. Conclusions Intratumoral CMP-001 was well-tolerated and provided both local and distant responses in patients with advanced melanoma with disease progression on prior PD-1 blockade. CMP-001 monotherapy induced systemic tumor regression in some patients, but duration of response was substantially increased by the addition of pembrolizumab. Acknowledgements This work was supported by Checkmate Pharmaceuticals. Medical writing assistance was provided by Cindy Rigby, PhD, of ApotheCom (San Francisco, CA) and was funded by Checkmate Pharmaceuticals. Trial Registration NCT02680184 Ethics Approval This study was approved by the WCG-WIRB, WIRB approval tracking number 20152597. Consent N/A References N/A

HER2 transactivation by the HER3 ligand heregulin (HRG) promotes an endocrine-resistant phenotype in the estrogen receptor-positive (ER+) luminal-B subtype of breast cancer. The underlying biological mechanisms that link them are, however, incompletely understood. Here, we evaluated the putative role of the lipogenic enzyme fatty acid synthase (FASN) as a major cause of HRG-driven endocrine resistance in ER+/HER2-negative breast cancer cells. MCF-7 cells engineered to stably overexpress HRG (MCF-7/HRG), an in vitro model of tamoxifen/fulvestrant-resistant luminal B-like breast cancer, showed a pronounced up-regulation of FASN gene/FASN protein expression. Autocrine HRG up-regulated FASN expression via HER2 transactivation and downstream activation of PI-3K/AKT and MAPK-ERK1/2 signaling pathways. The HRG-driven FASN-overexpressing phenotype was fully prevented in MCF-7 cells expressing a structural deletion mutant of HRG that is sequestered in a cellular compartment and lacks the ability to promote endocrine-resistance in an autocrine manner. Pharmacological inhibition of FASN activity blocked the estradiol-independent and tamoxifen/fulvestrant-refractory ability of MCF-7/HRG cells to anchorage-independently grow in soft-agar. In vivo treatment with a FASN inhibitor restored the anti-tumor activity of tamoxifen and fulvestrant against fast-growing, hormone-resistant MCF-7/HRG xenograft tumors in mice. Overall, these findings implicate FASN as a key enabler for endocrine resistance in HRG+/HER2-breast cancer and highlight the therapeutic potential of FASN inhibitors for the treatment of endocrine therapy-resistant luminal-B breast cancer. Fil: Menendez, Javier A.. Institut D'investigació Biomèdica de Girona Dr. Josep Trueta; España. Institut Català d'Oncologia ; España Fil: Mehmi, Inderjit. The Angeles Clinic And Research Institute; Estados Unidos Fil: Papadimitropoulou, Adriana. Academy of Athens; Grecia Fil: Steen, Travis Vander. Mayo Clinic; Estados Unidos Fil: Cuyàs, Elisabet. Institut D'investigació Biomèdica de Girona Dr. Josep Trueta; España. Institut Català d'Oncologia ; España Fil: Verdura, Sara. Institut Català d'Oncologia ; España. Institut D'investigació Biomèdica de Girona Dr. Josep Trueta; España Fil: Espinoza, Ingrid. University of Mississippi; Estados Unidos Fil: Vellón, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Atlas, Ella. University of Ottawa; Canadá Fil: Lupu, Ruth. Mayo Clinic Cancer Center; Estados Unidos. Mayo Clinic; Estados Unidos. Academy of Athens; Grecia

Background In the treatment-naive setting, PD-1 blockade is associated with greater response in T cell-inflamed vs non-T cell-inflamed tumors. CMP-001 is a CpG-A oligonucleotide TLR9 agonist in a virus-like particle that is hypothesized to activate tumor-associated plasmacytoid dendritic cells (pDCs) to secrete type I interferons. Through this activity, CMP-001 may convert the tumor microenvironment to a Th1-like chemokine milieu (eg, increased CXCL10) and induce an antitumor CD8+ T-cell response. We have recently reported that intratumoral injection of CMP-001 + IV pembrolizumab (pembro) had an acceptable safety profile and can reverse PD-1 blockade resistance in patients (pts) with melanoma (Milhem et al, SITC 2019). Regression was observed in injected and uninjected lesions. Herein we report pharmacodynamic and translational data. Methods This 2-part, open-label, multicenter, phase 1b study (NCT02680184) enrolled pts with metastatic/unresectable melanoma and stable disease (SD) or progressive disease (PD) on/after anti−PD-1 therapy. In part 1 (3+3 dose-escalation and dose-expansion), pts received CMP-001 + pembro. In part 2, pts received CMP-001 monotherapy. Determination of safety and clinical activity were the study's main objectives. Prespecified pharmacodynamic and translational studies evaluated serum chemokines and evaluated tumor biopsies using RNA and/or whole exome sequencing and immunohistochemistry for PD-L1 (reported as H-score), CD8, and CD303 (pDC marker). Results As of September 30, 2020, 159 pts (part 1) and 40 pts (part 2) have been treated. A greater median fold increase of serum CXCL10 (a marker of innate immunity, n=40) was observed in responders (R) to CMP-001 + pembro (18.8x) vs nonresponders (NR) after treatment (9.9x in SD; 6.15x in PD; differences were not statistically significant). Preliminary analyses showed that interferon gene expression distinguished R vs NR. Tumor biopsy analyses (part 1, n=139; part 2, n=34) showed that pts with high PD-L1, high CD8+ T cells, or inflamed transcriptional signatures at baseline were less likely to respond to CMP-001 + pembro vs pts without inflammation markers at baseline. Baseline mean PD-L1 expression (H-score) was 8.1 in R (n=10) vs 21.8 in NR (n=49). Posttreatment biopsies generally showed increased PD-L1, CD8+ T cells, and inflamed transcriptional signatures in R vs NR. Neither tumor mutational burden nor baseline pDC density distinguished R vs NR. Conclusions In pts with anti-PD-1 refractory melanoma, intratumoral CMP-001 ± pembro appears to disproportionately induce antitumor responses in noninflamed tumors. Clinical response to CMP-001 ± pembro was associated with induction of markers of both innate and adaptive antitumor immunity. Citation Format: Jason John Luke, Riyue Bao, John M. Kirkwood, Yousef Zakharia, Diwakar Davar, Elizabeth Buchbinder, Theresa Medina, Adil Daud, Antoni Ribas, Jiaxin Niu, Geoffrey Gibney, Kim Margolin, Anthony J. Olszanski, Inderjit Mehmi, Takami Sato, Montaser Shaheen, Aaron Morris, Dmitri Bobilev, Katie Campbell, George Weiner, James E. Wooldridge, Arthur M. Krieg, Mohammed Milhem. CMP-001 demonstrates improved response in noninflamed anti-PD-1 refractory melanoma and response is associated with serum CXCL10 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT032.

TPS9589 Background: Interleukin 6 (IL-6) functions in the maintenance of hepatocytes, haemotopoietic progenitor cells, a variety of other tissues, and regulates the innate and adaptive immune system. IL-6 may play a role as a chronic inflammatory mediator in altering levels of acute phase proteins synthesized by the liver and circulating myeloid cells which have been shown to be associated with short survival with checkpoint inhibition and which are immune suppressive. The immunomodulatory properties of interleukin-6 may in part also be responsible for immune related adverse events, given the reversal of those toxicities observed with IL-6 receptor blockade in clinical practice. To assess if blockade of IL-6 binding is associated with a decrease in irAEs and/or an increase in efficacy defined as overall response rate (ORR) at week 24 in patients receiving ICB, we added tocilizumab to ipilimumab and nivolumab therapy. Methods: The current phase II trial is a two-stage design to assess the safety, tolerability, and grades 3-5 immune related toxicities of tocilizumab administered every 6 weeks up to week 24 in combination with ipilimumab at 1 mg/kg and nivolumab at 3 mg/kg every 3 weeks for 4 doses each during a 12 week induction period, then administered every 6 weeks with nivolumab at 240 mg flat dose every 2 weeks in maintenance for up to 24 weeks, and nivolumab alone will be given at 480 mg flat dose every 4 weeks thereafter for up to 2 years. Eligible patients include those age 18 or older with measurable and unresectable stages III/IV melanoma (cutaneous, acral, mucosal), without prior systemic treatment for metastatic disease. Adjuvant therapy (IFN-alpha, ipilimumab and/or nivolumab, or pembrolizumab) is allowed. Patients with metastatic melanoma of brain are allowed, if neurologically stable and off immunosuppressive steroids. A total of 18 patients will be treated in the first stage, and 49 additional patients in the second stage for a total of 67. The comparator data are from the N3I1 arm of Checkmate-511 trial, in which treatment-related grades 3-5 irAEs were 33.9% with a 45.6% response rate (1). Prespecified activity goal for the first stage of accrual has been met; second stage accrual began in January 2021. References: (1) Lebbé C, Meyer N, Mortier L, Marquez-Rodas I, et al. Evaluation of Two Dosing Regimens for Nivolumab in Combination With Ipilimumab in Patients With Advanced Melanoma: Results From the Phase IIIb/IV CheckMate 511 Trial. Journal of Clinical Oncology 2019 37:11, 867-875. Clinical trial information: NCT03999749.

TPS5600 Background: KIF18A is a mitotic kinesin motor protein that regulates chromosome positioning during cell division and is overexpressed in a subset of human cancers. TP53 mutant unstable aneuploid cancer cells with chromosomal instability (CIN) features are dependent on KIF18A motor activity to prevent lethal multipolar cell division. Preclinical data demonstrate that treatment with AMG 650; an oral, first in class, selective small molecule inhibitor of KIF18A may be safe and tolerable. We are conducting a first-in-human phase 1 study with AMG 650 in adult subjects with locally advanced or metastatic solid tumors with TP53MUT, triple negative breast cancer (TNBC), high grade serous ovarian cancer (HGSOC) or serous like endometrial cancers and other solid tumors. Methods: In this phase 1, multicentric, dose escalation and dose expansion study we evaluate the safety and tolerability of AMG 650 monotherapy in patients with advanced/metastatic solid tumors (NCT04293094). The main objective is to determine the maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D) based on emerging safety, efficacy, and pharmacodynamics (PD) data prior to reaching the MTD. Key inclusion criteria include the presence of measurable disease and diagnosis of advanced/metastatic triple negative breast cancer (TNBC), high-grade serous ovarian cancer (HGSOC), serous-like endometrial cancer or other solid tumors with documented TP53 mutations. In the dose expansion phase, participants with locally advanced or metastatic TNBC or HGSOC will be treated with the preliminary RP2D identified from the dose exploration part of the study. Primary endpoints include the incidence of Dose Limiting Toxicities (DLTs),Treatment-Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), Treatment-related Adverse Events and the evaluation of the number of participants who experience a clinically significant change from baseline in vital signs, electrocardiogram and laboratory tests parameters. Secondary endpoints include Objective Response Rate, Duration of Response, Progression-free Survival, Clinical Benefit Rate, Time to Response, Time to Progression, Overall Survival (OS), Maximum Plasma Concentration (Cmax) of AMG 650, Time to Maximum Plasma Concentration (Tmax) of AMG 650 as well as Area Under the Plasma Concentration-time Curve (AUC) Over the Dosing Interval for AMG 650. Continuous monitoring of toxicity is conducted. The study began enrolling pts in March 2020 and is ongoing. For more information, please contact Amgen Medical Information: medinfo@amgen.com Clinical trial information: NCT04293094.

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that upon activation by the toxicant 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) stimulates gene expression and toxicity. AHR is also important for normal mouse physiology and may play a role in cancer progression in the absence of environmental toxicants. The objective of this report was to identify AHR-dependent genes (ADGs) whose expression is regulated by AHR in the absence of toxicants. RNA-Seq analysis revealed that AHR regulated the expression of over 600 genes at an FDR

61 Background: Eflapegrastim (E) is a novel, long-acting GCSF comprised of recombinant human GCSF covalently linked to human IgG4 Fc fragment via a PEG linker (MW, 72 kDa). E showed increased potency vs pegfilgrastim (P) in preclinical and Phase I and II trials. Two identically designed Phase III pivotal trials (NCT02643420, NCT02953340) were conducted globally with a fixed dose of 13.2 mg E containing 3.6 mg GCSF to evaluate E vs P (6 mg) in pts receiving chemotherapy for early-stage breast cancer. Methods: Each open-label trial randomized pts 1:1 to a single subcutaneous dose of E 13.2 mg/0.6 mL or P 6 mg/0.6 mL on Day 2 of each of four 21-day cycles following Day 1 adj/neoadj docetaxel 75 mg/m2 + cyclophosphamide 600mg/m2 (TC) . The primary endpoint was to demonstrate E non-inferiority (NI) to P as measured by mean duration of severe neutropenia (DSN) in Cycle 1. Results: A total 643 intent-to-treat pts (314 E/329 P) with median age 60 yrs (24–88) were enrolled. Cycle 1 mean (SD) DSN was 0.24 (0.581) vs 0.36 (0.789) days for E and P, confirming NI (p75kg) pts, DSN was reduced for E vs P. In Cycle 1, E showed an absolute risk reduction for severe neutropenia of 6.5% vs P (27.1% relative risk reduction, p

539 Background: Eflapegrastim (E) is a novel long-acting GCSF comprised of recombinant human GCSF covalently linked to human IgG4 Fc fragment via a PEG linker (MW, 72 kDa). E showed increased potency vs pegfilgrastim (P) in preclinical and Phase I and II trials. Two identically designed Phase III pivotal trials (NCT02643420, NCT02953340) were conducted globally with a fixed dose of 13.2 mg E containing 3.6 mg GCSF to evaluate E vs P (6 mg) in pts receiving chemotherapy for early-stage breast cancer. Methods: Each open-label trial randomized pts 1:1 to a single subcutaneous dose of E 13.2 mg/0.6 mL or P 6 mg/0.6 mL on Day 2 of each of four 21-day cycles following Day 1 adj/neoadj docetaxel 75 mg/m2 + cyclophosphamide 600mg/m2 (TC). The primary endpoint was to demonstrate E non-inferiority (NI) to P as measured by mean duration of severe neutropenia (DSN) in Cycle 1. Results: A total 643 intent-to-treat pts (314 E/329 P) with median age 60 yrs (24–88) were enrolled. Cycle 1 mean (SD) DSN was 0.24 (0.581) vs 0.36 (0.789) days for E and P, confirming NI (p < .0001) and suggesting statistical superiority (p < .029). DSN NI was also shown across cycles 2–4. Among subgroups, including elderly (≥65 yrs) and overweight ( > 75kg) pts, DSN was reduced for E vs P. In Cycle 1, E showed an absolute risk reduction for severe neutropenia of 6.5% vs P (27.1% relative risk reduction, p < .043). Neutropenic complications (hospitalization and/or anti-infective use) were 2.9% and 4.0% for E and P (p = ns). Incidence of FN was low for both E and P, 1.6% vs 1.8% in Cycle 1 and 3.2% vs 3.0% overall. ANC profiles showed sustained increased levels for E vs P in the recovery phase across all cycles. Safety profiles were similar for E and P, including primarily for expected hematologic AEs and for bone pain and other musculoskeletal pain. Conclusions: These integrated pivotal trial results confirm a similar safety profile and non-inferiority in reducing neutropenic risk for E at a lower GCSF dose vs P. The data also suggests the potential for increased potency of E to deliver improved clinical benefit, a possibility that warrants further clinical trials. Clinical trial information: NCT02643420, NCT02953340.

140 Background: Reduced-dose nivolumab in combination with standard-dose ipilimumab was shown to improve overall response rate (58%), progression free survival (11.5 months), and overall survival compared to ipilimumab alone in Checkmate 067. Improved outcomes were accompanied by an increased risk of toxicities with a 59% rate of grade 3-4 toxicities for the combination. Keynote 029 evaluated standard-dose pembrolizumab with reduced-dose ipilimumab with a slightly lower risk of grade 3-4 toxicities at 45%. Here we report outcomes for standard-dose nivolumab combined with reduced-dose ipilimumab in metastatic melanoma. Methods: We conducted a retrospective review of metastatic melanoma patients that received standard-dose nivolumab with reduced-dose ipilimumab at West Virginia University Cancer Institute. Response to therapy and incidence of immune-related adverse events were assessed. Results: From February 2017 to October 2018, 11 patients received the alternative dosing regimen. Only 1 (9%) patient experienced a grade 3-4 toxicity, and 3 (27%) additional patients experienced a grade 1-2 toxicity. The overall response rate was 54%. Conclusions: Standard-dose nivolumab in combination with reduced-dose ipilimumab is better tolerated than reduced-dose nivolumab with standard-dose ipilimumab without a loss in overall response rate.

Background: CMP-001 comprises a CpG-A oligodeoxynucleotide packaged within a virus-like particle. It is designed to activate tumor-associated plasmacytoid dendritic cells via TLR9 inducing an interferon-rich tumor microenvironment and anti-tumor CD8+ T cell responses. Materials and Methods: CMP-001-001 is an ongoing phase Ib trial evaluating intratumoral (IT) CMP-001 in combination with pembrolizumab (administered per label) in subjects with advanced melanoma resistant (either did not respond or progressed) on prior anti-PD-1 monotherapy or in combination. During dose escalation, subjects were enrolled to cohorts of ≥ 3 subjects at CMP-001 doses of 1, 3, 5, 7.5, and 10 mg in two dosing schedules (weekly for 7w, followed by q3w; or weekly for 2w, followed by q3w). CMP-001 was administered IT into an accessible lesion(s), and response assessed in all target lesions (injected and non-injected) by RECIST v1.1. Study therapy was continued until progression, toxicity, investigator decision or withdrawal of consent. Baseline and on-therapy serum was collected for cytokine analysis. Immunohistochemical and RNA-Seq analysis was performed on available pre- and post-treatment tumor biopsies. Results: As of December 31, 2017, 68 subjects have been treated (44 in Escalation and 24 in Expansion). Safety data from 63 subjects demonstrated a manageable acute toxicity profile consisting predominately of fever, N/V, headache, hypotension and rigors. Grade 3/4 related AEs reported in ≥1 subject; hypotension (n=7), anemia (n=2), chills (n=2), hypertension (n=2) and fever (n=2). The Objective Response Rates (ORR) across all dose cohorts on weekly (n=40) and q3week schedules (n=13) were 22.5% (9/40; 95 % CI 11-39%) and 7.7%% (1/13; 95% CI 0-36%) respectively. For subjects dosed weekly at 3 and 5 mg, the ORR was 33.3% (6/18 95% CI 13-59%). Of the 10 responders, 1 progressed (w36), 2 withdrew consent (w13, w25), 7 remain on study with 2 subjects maintaining their response though w72. Regression of non-injected tumors occurred in cutaneous, nodal, hepatic, and splenic metastases. CMP-001 induced TLR9 activation with a median 5.9 fold increase in serum CXCL10 (range of 0.9 - 276.3; mean fold increase of 21.8 with SD=48.8; n=39). Immunohistochemical and RNA-Seq analysis of tumor biopsies revealed increases in tumor-infiltrating CD8 T cells (>5 fold), PD-L1 expression (>3 fold increase in H score), and transcriptional signature of inflammation in 2/4 subjects with analyzable pre-and post-treatment samples. Conclusions: CMP-001 in combination with pembrolizumab resulted in objective, durable tumor responses with tolerable toxicities in subjects with advanced melanoma resistant to prior anti-PD-1 therapy. CMP-001 dosing at 5 mg/weekly has been selected for further evaluation in the ongoing dose expansion phase of this study. Citation Format: Mohammed Milhem, Rene Gonzales, Theresa Medina, John M. Kirkwood, Elizabeth Buchbinder, Inderjit Mehmi, Jiaxin Niu, Montaser Shaheen, Ryan Weight, Kim Margolin, Jason Luke, Aaron Morris, David Mauro, Arthur M. Krieg, Antoni Ribas. Intratumoral toll-like receptor 9 (TLR9) agonist, CMP-001, in combination with pembrolizumab can reverse resistance to PD-1 inhibition in a phase Ib trial in subjects with advanced melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT144.

e21609Background: Combined immune checkpoint inhibition (ICI) has demonstrated improved survival in patients (pts) with advanced melanoma. Several factors have been associated with greater benefit ...

e21552Background: Metastatic melanoma (MM) continues to present a challenge in clinical oncology. Anti-PD-1 antibodies (nivolumab, pembrolizumab) have improved outcomes for a significant number of ...

e12513Background: Eflapegrastim is a novel investigational biologic comprised of recombinant human G-CSF covalently linked to the human immunoglobulin G4FC fragment using proprietary LAPSCOVERY™ te...

Overexpression of the lipogenic enzyme fatty acid synthase (FAS) is a common molecular feature in subsets of sex-steroid-related tumors including endometrium and breast carcinomas that are associated with poor prognosis. Pharmacological inhibition of tumor-associated FAS hyperactivity is under investigation as a chemotherapeutic target. We examined the effects of the mycotoxin cerulenin (a covalent FAS inactivator), and the novel small compound C75 (a slow-binding FAS inhibitor) on estradiol (E2)- and tamoxifen (TAM)-stimulated ER-driven molecular responses in Ishikawa cells, an in vitro model of well-differentiated human endometrial carcinoma. We evaluated the effects of FAS inhibition on E2- and TAM-induced estrogen receptor (ER) transcriptional activity by using transient cotransfection assays with an estrogen-response element reporter construct (ERE-Luciferase). Antiestrogenic effects of cerulenin and C75 were observed by dose-dependent inhibition of E2-stimulated ERE-dependent transcription, whereas FAS inhibitors did not significantly increase the levels of ERE transcriptional activity in the absence of E2. Moreover, pharmacological blockade of FAS activity completely abolished TAM-stimulated ERE activity. To address the reliability of transient transfection assays, the effects of FAS inhibitors on E2-inducible gene products were evaluated. FAS blockade induced a dose-dependent decrease in E2-inducible alkaline phosphatase activity. E2-stimulated accumulation of progesterone receptor (PR) and HER-2/neu oncogene was abolished in the presence of FAS blockers. FAS inhibition also resulted in a marked downregulation of E2-stimulated ERalpha expression, and noticeably impaired E2-induced ERalpha nuclear accumulation. A dose-dependent decrease in cell proliferation and cell viability was observed after FAS blockade. A Cell Death ELISA, detecting DNA fragmentation, demonstrated that FAS inhibitors stimulated apoptosis of Ishikawa cells. The analysis of critical E2- and TAM-related cell cycle proteins revealed an increase of both the expression and the nuclear accumulation of cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1 following FAS inhibition. To rule out non-FAS cerulenin- and C75-related effects, we finally monitored ER signaling after silencing of FAS gene expression using the highly sequence-specific mechanism of RNA interference (RNAi). The concentrations of E2 and TAM inducing half-maximal ERE activity (EC50) dramatically increased (100 times) in FAS RNAi-transfected Ishikawa cells. Moreover, depletion of FAS by RNAi also caused loss of ERalpha expression, downregulation of PR, and accumulation of p21WAF1/CIP1 and p27Kip1 in E2-stimulated Ishikawa cells. If chemically stable FAS inhibitors or cell-selective vector systems able to deliver RNAi targeting FAS gene demonstrate systemic anticancer effects in vivo, our results render FAS as a novel target for the prevention and treatment of endometrial carcinoma.

CYR61 (CNN1), a member of the cysteine rich 61/connective tissue growth factor/nephroblastoma overexpressed (CYR61/CTFG/NOV) family of growth regulators (CNN), is a pro-angiogenic factor that mediates diverse roles in development, cell proliferation, and tumorigenesis. We have recently shown that CYR61 is overexpressed in invasive and metastatic human breast cancer cells. Accordingly, elevated levels of CYR61 in breast cancer are associated with more advanced disease. Unfortunately, the exact mechanisms by which CYR61 promotes an aggressive breast cancer phenotype are still largely unknown. This review examines the functional role of CYR61 in breast cancer disease, presenting evidence that CYR61 signaling may play a major role in estrogen- as well as growth factor-dependent breast cancer progression. We also emphasize the functional significance of the molecular connection of CYR61 and its integrin receptor alpha(v)beta(3) enhancing breast cancer aggressiveness. Moreover, we describe experimental evidence that establishes a novel role for CYR61 determining the protection of human breast cancer cells against chemotherapy-induced apoptosis through its interactions with the integrin receptor alpha(v)beta(3). All these findings delineate a new noteworthy function of a CYR61/alpha(v)beta(3) autocrine-paracrine signaling pathway within both angiogenesis and breast cancer progression, which would allow a dual anti-angiogenic and anti-tumor benefit with a single drug.

Heregulin (HRG) is an activator of the erbB2-, erbB3- and erbB4-(erbB-2/3/4) signaling pathway. Transfection of full-length HRG cDNA into the estrogen (E2)-dependent cell line MCF-7 promoted an invasive E2-independent phenotype, as well as persistent activation of the erbB-2/3/4 receptors. Moreover, HRG expression in MCF-7 cells renders the cells sensitive to the topoisomerase II inhibitor doxorubicin (Doxo). In an attempt to dissociate the tumorigenic effect of HRG from the sensitizing effect to chemotherapy, we constructed a structural deletion mutant of HRG. Transfection of the deletion mutant of HRG described in this study (HRG/M) into MCF-7 cells resulted in the dissociation of the tumor-promoting activity of HRG from the sensitization to Doxo, that is, although the cells did not become more aggressive or E2-independent they became more sensitive to Doxo. HRG/M was unable to autophosphorylate the erbB receptors and did not affect the level of MAPK phosphorylation. Furthermore, the intracellular localization of the protein was different from that of the full-length protein. Our data show that the HRG/M sequences are sufficient to sensitize MCF-7 cells to Doxo, and provide evidence that this sensitization is independent of erbB2 activation.

Purpose The decision for treating breast cancer patients with trastuzumab is based on HER-2 amplification and/or overexpression. Methods Using MCF-7 cells (Her-2 ±) engineered to overexpress heregulin (MCF-7/HRG), a ligand for the Her-2/3/4 network, we investigated whether HRG-induced transactivation of Her-2 affected breast cancer cell sensitivity to chemotherapy and whether trastuzumab trigger receptor-enhanced chemosensitivity (REC) when combined with chemotherapy without Her-2 overexpression. Results MCF-7/HRG cells were more than 10-fold resistant to the alkylating agent cisplatin (CDDP), while trastuzumab coexposure completely reversed HRG-promoted CDDP resistance. A synergistic interaction between trastuzumab in combination with CDDP (paclitaxel or vincristine) was obtained in MCF-7/HRG cells. Trastuzumab prevented activation of the antiapoptotic and proliferative cascades and inhibited HRG-induced Her-2/3 phosphorylation. CDDP efficacy was enhanced by trastuzumab in cells expressing endogenously high levels of HRG. Conversely, trastuzumab coexposure was ineffective in enhancing chemotherapy efficacy in cells that did not secrete HRG, such as MCF-7 cells overexpressing a structural mutated HRG isoform. Therefore, trastuzumab-induced REC, in the absence of Her-2 overexpression, occurs through the kinase activity of Her-2/3. Interestingly, HRG expression in tumor biopsies from invasive breast carcinomas (n = 189) revealed that, whereas the minority (12%) of Her-2 positive tumors (n = 60; 32%) demonstrated Her-2 phosphorylation, the majority (67%) of HRG-overexpressing and Her-2 tumors (n = 57; 30%) were in active Her-2 status. Conclusion We demonstrate that assessment of HRG expression and Her-2 activation define a particular breast cancer patient population for which trastuzumab plus CDDP or taxol are extremely efficient without Her-2 overexpression.

Elevated levels of p21 WAF1/CIP1 , an important mediator of DNA repair, have been observed in various aggressive tumors as well as linked to chemoresistance. We examined whether heregulin (HRG), a member of the EGF-like growth factor family closely related to breast cancer tumurigencsis and metastasis, modulates p21 WAF1/CIP1 expression and cellular localization. We used a model system that consisted of MCF-7 cells and MCF-7 cells engineered to overexpress the full-length cDNA of the human HRG gene (MCF-7/HRG). MCF-7/HRG cells demonstrate constitutive hyperactivation of Her-2/neu receptor as well as activation of down-stream PI-3'K/AKT and MAPK signaling cascades. Immunoblotting analyses showed that MCF-7/HRG cells significantly up-regulate p21 WAF1/CIP1 expression relative to control MCF-7/pBABE cells, while a strong nuclear accumulation of p21 WAF1/CIP1 in MCF-7/HRG cells was revealed by immunofluorescence microscopy studies. Protein degradation analyses demonstrated that the half-life of p21 WAF1/CIP1 protein was increased from -35 min in control MCF-7/pBABE cells to ≥3 h in MCF-7/HRG cells. Pharmacological inactivation of the PI-3'K/AKT and MAPK completely prevented HRG-induced accumulation of p21 WAF1/CIP1 . A structural deletion mutant of HRG (HRG-M4) lacking the N-terminus sequence and the cytoplasmic-transmembrane region of HRG was generated to investigate whether secretion of HRG and transactivation of Her-2/neu actively contributed to HRG-regulated p21 WAF1/CIP1 expression and cellular localization. MCF-7 cells engineered to overexpress HRG-M4 did not demonstrate either activation of Her-2/neu, PI-3'K/AKT, or MAPK. Remarkably, HRG-M4 overexpression completely abolished the ability of HRG to promote nuclear accumulation of p21 WAF1/CIP1 and concomitantly enhanced the apoptotic effects of cisplatin towards breast cancer cells. This novel interplay between HRG and p21 WAF1/CIP1 strongly suggests that one mechanism of HRG-rcgulmcd breast cancer cell proliferation, survival, and/or sensitivity to genotoxic damage is to stabilize and promote a nuclear accumulation of p21 WAF1/CIP1

The angiogenic inducer CYR61 is differentially overexpressed in breast cancer cells exhibiting high levels of Heregulin (HRG), a growth factor closely associated with a metastatic breast cancer phenotype. Here, we examined whether CYR61, independently of HRG, actively regulates breast cancer cell survival and chemosensitivity, and the pathways involved. Forced expression of CYR61 in HRG-negative MCF-7 cells notably upregulated the expression of its own integrin receptor alphavbeta3 (200 times). Small peptidomimetic alphavbeta3 integrin antagonists dramatically decreased cell viability of CYR61-overexpressing MCF-7 cells, whereas control MCF-7/V remained insensitive. Mechanistically, functional blockade of alphavbeta3 specifically abolished CYR6-induced hyperactivation of ERK1/ERK2 MAPK, whereas the activation status of AKT did not decrease. Moreover, CYR61 overexpression rendered MCF-7 cells significantly resistant (10-fold) to Taxol-induced cytotoxicity. Remarkably, alphavbeta3 inhibition converted the CYR61-induced Taxol-resistant phenotype into a hypersensitive one. Thus, the augmentation of Taxol-induced apoptotic cell death in the presence of alphavbeta3 antagonists demonstrated a strong synergism as verified by the terminal transferase-mediated dUTP nick-end labeling (TUNEL) assay and by flow cytometric analysis for DNA content. Indeed, functional blockade of alphavbeta3, similarly to the pharmacological MAPK inhibitor U0126, synergistically increased both the proportion of CYR61-overexpressing breast cancer cells in the G2 phase of the cell cycle and the appearance of sub-G1 hypodiploid (apoptotic) cells caused by Taxol. Strikingly, CYR61 overexpression impaired the accumulation of wild-type p53 following Taxol exposure, while inhibition of alphavbeta3 or ERK1/ERK2 MAPK signalings completely restored Taxol-induced upregulation of p53. Moreover, antisense downregulation of CYR61 expression abolished the anchorage-independent growth of breast cancer cells engineered to overexpress HRG, and significantly increased their sensitivity to Taxol. Our data provide evidence that CYR61 is sufficient to promote breast cancer cell proliferation, cell survival, and Taxol resistance through a alphavbeta3-activated ERK1/ERK2 MAPK signaling. The identification of a 'CYR61-alphavbeta3 autocrine loop' in the epithelial compartment of breast carcinoma strongly suggests that targeting alphavbeta3 may simultaneously prevent breast cancer angiogenesis, growth, and chemoresistance.

We designed our experiments to evaluate whether fatty acid synthase (FAS), a lipogenic enzyme linked to tumor virulence in population studies of human cancer, is necessary for the malignant transformation induced by Her-2/neu (erbB-2) oncogene, which is overexpressed not only in invasive breast cancer but also in premalignant atypical duct proliferations and in ductal carcinoma in situ of the breast. To avoid the genetic complexities associated with established breast cancer cell lines, we employed NIH-3T3 mouse fibroblasts engineered to overexpress human Her-2/neu coding sequence. NIH-3T3/Her-2 cells demonstrated a significant upregulation of FAS protein expression, which was dependent on the upstream activation of mitogen-activated protein kinase and phosphatidylinositol 3′-kinase/AKT pathways. Remarkably, pharmacological FAS blockade using the mycotoxin cerulenin or the novel small compound C75 completely suppressed the state of Her-2/neu-induced malignant transformation by inhibiting the ability of NIH-3T3/Her-2 cells to grow under either anchorage-independent (i.e., to form colonies in soft agar) or low-serum monolayer conditions. Moreover, NIH-3T3/Her-2 fibroblasts were up to three times more sensitive to chemical FAS inhibitors relative to untransformed controls as determined by MTT-based cell viability assays. In addition, pharmacological FAS blockade preferentially induced apoptotic cell death of NIH-3T3/Her-2 fibroblasts, as determined by an ELISA for histone-associated DNA fragments and by the terminal deoxynucleotidyltransferase (TdT)-mediated nick end labeling assay (TUNEL). Interestingly, the degree of Her-2/neu oncogene expression in a panel of breast cancer cell lines was predictive of sensitivity to chemical FAS inhibitors-induced cytotoxicity, while low-FAS expressing and chemical FAS inhibitors-resistant MDA-MB-231 breast cancer cells became hypersensitive to FAS blockade when they were engineered to overexpress Her-2/neu. Our observations strongly suggest that inhibition of FAS activity may provide a new molecular avenue for chemotherapeutic prevention and/or treatment of Her-2/neu-related breast carcinomas. © 2004 Wiley-Liss, Inc.