Randomized Phase II Study of Gemcitabine With or Without ATR Inhibitor Berzosertib in Platinum-Resistant Ovarian Cancer: Final Overall Survival and Biomarker Analyses.

PURPOSE: The multicenter, open-label, randomized phase 2 NCI-9944 study (NCT02595892) demonstrated that addition of ATR inhibitor (ATRi) berzosertib to gemcitabine increased progression-free survival (PFS) compared to gemcitabine alone (hazard ratio [HR]=0.57, one-sided log-rank P = .044, which met the one-sided significance level of 0.1 used for sample size calculation). METHODS: We report here the final overall survival (OS) analysis and biomarker correlations (ATM expression by immunohistochemistry, mutational signature 3 and a genomic biomarker of replication stress) along with post-hoc exploratory analyses to adjust for crossover from gemcitabine to gemcitabine/berzosertib. RESULTS: At the data cutoff of January 27, 2023 (>30 months of additional follow-up from the primary analysis), median OS was 59.4 weeks with gemcitabine/berzosertib versus 43.0 weeks with gemcitabine alone (HR 0.79, 90% CI 0.52 to 1.2, one-sided log-rank P = .18). An OS benefit with addition of berzosertib to gemcitabine was suggested in patients stratified into the platinum-free interval ≤3 months (N = 26) subgroup (HR, 0.48, 90% CI 0.22 to 1.01, one-sided log-rank P =.04) and in patients with ATM-negative/low (N = 24) tumors (HR, 0.50, 90% CI 0.23 to 1.08, one-sided log-rank P = .06). CONCLUSION: The results of this follow-up analysis continue to support the promise of combined gemcitabine/ATRi therapy in platinum resistant ovarian cancer, an active area of investigation with several ongoing clinical trials.

Case report: Response to everolimus in a patient with platinum resistant, high grade serous ovarian carcinoma with biallelic TSC2 inactivation.

Background: Patients with platinum-resistant recurrent high grade serous ovarian carcinoma have poor outcomes and limited treatment options. Case presentation: We present a case of a 48-year-old woman with platinum-resistant high grade serous ovarian carcinoma harboring the pathogenic TSC2 R611Q variant with concomitant single copy loss of TSC2 (suggesting biallelic TSC2 inactivation) identified in targeted tumor sequencing. The patient was treated with the mTOR inhibitor everolimus, with an excellent response by imaging and a marked decrease in CA125; she remained on everolimus for 19 months until she developed progressive disease. Conclusions: While mTOR inhibition is frequently used in tumors associated with tuberous sclerosis complex (TSC), such as lymphangioleiomyomatosis and malignant perivascular epithelioid cell tumors, this is the first case of a patient with ovarian cancer harboring TSC1/2 mutations who responded to mTOR inhibition. This case highlights the utility of targeted DNA sequencing in the management of ovarian carcinoma and demonstrates the value of tumor-agnostic targeted therapies.

Combined aromatase, CDK4/6 and PI3K blockade using letrozole/abemaciclib/LY3023414 in endometrial cancer.

Several lines of preclinical evidence indicate that combining PI3K and CDK4/6 inhibitors may further enhance the efficacy of hormonal therapy by overcoming de novo and acquired resistance to PI3K and CDK4/6 blockade. We evaluated the combination of abemaciclib, letrozole and LY3023414 (an orally available, selective inhibitor of the class I PI3K isoforms and mTORC1/2) in recurrent endometrial cancer (EC). This study was terminated prematurely after 5 patients initiated protocol therapy due to discontinuation of further development of LY3023414. We report our findings from these patients, including one with recurrent endometrioid EC with AKT1, CTNNB1 and ESR1 hotspot mutations who had previously progressed through letrozole/everolimus and achieved a partial response to letrozole/abemaciclib/LY3023414.

Endometrial Cancer Risk Among Germline BRCA1/2 Pathogenic Variant Carriers: Review of Our Current Understanding and Next Steps.

PURPOSE: To review the literature exploring endometrial cancer (EC) risk among surgical candidates with germline BRCA1/2 pathogenic variants (PVs) to guide decisions around risk-reducing (rr) hysterectomy in this population. DESIGN: A comprehensive review was conducted of the current literature that influences clinical practice and informs expert consensus. We present our understanding of EC risk among BRCA1/2 PV carriers, the risk-modifying factors specific to this patient population, and the available research technology that may guide clinical practice in the future. Limitations of the existing literature are outlined. RESULTS: Patients with BRCA1/2 PVs, those with a personal history of tamoxifen use, those who desire long-term hormone replacement therapy, and/or have an elevated BMI are at higher risk of EC, primarily endometrioid EC and/or uterine papillary serous carcinoma, and may benefit from rr-hysterectomy. Although prescriptive clinical guidelines specific to BRCA1/2 PV carriers could inform decisions around rr-hysterectomy, limitations of the current literature prevent more definitive guidance at this time. A large population-based study of a contemporary cohort of BRCA1/2 PV carriers with lifetime follow-up compared with cancer-gene negative controls would advance this topic and facilitate care decisions. CONCLUSION: This review validates a potential role for rr-hysterectomy to address EC risk among surgical candidates with BRCA1/2 PVs. Evidence-based clinical guidelines for rr-hysterectomy in BRCA1/2 PV carriers are essential to ensure equitable access to this preventive measure, supporting insurance coverage for patients with either BRCA1 or BRCA2 PVs to pursue rr-hysterectomy. Overall, this review highlights the complexity of EC risk in BRCA1/2 PV carriers and offers a comprehensive framework to shared decision making to inform rr-hysterectomy for BRCA1/2 PV carriers.

Transforming ovarian cancer care by targeting minimal residual disease.

Frontline treatment and resultant cure rates in patients with advanced ovarian cancer have changed little over the past several decades. Here, we outline a multidisciplinary approach aimed at gaining novel therapeutic insights by focusing on the poorly understood minimal residual disease phase of ovarian cancer that leads to eventual incurable recurrences.

Niraparib and dostarlimab for the treatment of recurrent platinum-resistant ovarian cancer: results of a Phase II study (MOONSTONE/GOG-3032).

OBJECTIVE: This study assessed the efficacy, safety, and health-related quality of life (HRQoL) of the treatment regimen of dostarlimab, a programmed death-1 inhibitor, combined with niraparib, a poly (ADP-ribose) polymerase inhibitor, in patients with BRCA wild type (BRCAwt) recurrent platinum-resistant ovarian cancer (PROC) who had previously received bevacizumab treatment. METHODS: This Phase II, open-label, single-arm, multicenter study, conducted in the USA, enrolled patients with recurrent PROC to receive niraparib and dostarlimab until disease progression or unacceptable toxicity (up to 3 years). A preplanned interim futility analysis was performed after the first 41 patients had undergone ≥1 radiographic evaluation (approximately 9 weeks from the first treatment). RESULTS: The prespecified interim futility criterion was met and the study was therefore terminated. For the 41 patients assessed, the objective response rate (ORR) was 7.3% (95% confidence interval: 1.5-19.9); no patients achieved a complete response, 3 patients (7.3%) achieved a partial response (duration of response; 3.0, 3.8, and 9.2 months, respectively), and 9 patients (22.0%) had stable disease. In total, 39 patients (95.1%) experienced a treatment-related adverse event, but no new safety issues were observed. HRQoL, assessed using FOSI, or Functional Assessment of Cancer Therapy - Ovarian Symptom Index scores, worsened over time compared with baseline scores. CONCLUSIONS: The study was terminated due to the observed ORR at the interim futility analysis. This highlights a need for effective therapies in treating patients with recurrent BRCAwt PROC.

Dynamics of the DYNLL1-MRE11 complex regulate DNA end resection and recruitment of Shieldin to DSBs.

The extent and efficacy of DNA end resection at DNA double-strand breaks (DSB) determine the repair pathway choice. Here we describe how the 53BP1-associated protein DYNLL1 works in tandem with the Shieldin complex to protect DNA ends. DYNLL1 is recruited to DSBs by 53BP1, where it limits end resection by binding and disrupting the MRE11 dimer. The Shieldin complex is recruited to a fraction of 53BP1-positive DSBs hours after DYNLL1, predominantly in G1 cells. Shieldin localization to DSBs depends on MRE11 activity and is regulated by the interaction of DYNLL1 with MRE11. BRCA1-deficient cells rendered resistant to PARP inhibitors by the loss of Shieldin proteins can be resensitized by the constitutive association of DYNLL1 with MRE11. These results define the temporal and functional dynamics of the 53BP1-centric DNA end resection factors in cells.

Clinical and translational advances in ovarian cancer therapy.

Ovarian cancer is an aggressive disease that is frequently detected at advanced stages and is initially very responsive to platinum-based chemotherapy. However, the majority of patients relapse following initial surgery and chemotherapy, highlighting the urgent need to develop new therapeutic strategies. In this Review, we outline the main therapeutic principles behind the management of newly diagnosed and recurrent epithelial ovarian cancer and discuss the current landscape of targeted and immune-based approaches.

Durable remission in a patient with ERBB2-amplified recurrent mucinous ovarian carcinoma treated with Trastuzumab-Carboplatin-Paclitaxel.

Patients with advanced stage or recurrent mucinous ovarian carcinoma exhibit poor response to standard platinum- and taxane-based chemotherapy and poor prognosis. We report a 29-year-old patient with recurrent ERBB2-amplified mucinous ovarian carcinoma (with expansile growth pattern at initial diagnosis and previously treated with adjuvant capecitabine/oxaliplatin) who underwent optimal secondary cytoreduction followed by 6 cycles of carboplatin/paclitaxel/trastuzumab and 1-year maintenance trastuzumab. This patient remains without radiologic or biochemical evidence of disease for more than 3 years after secondary cytoreduction. This case supports routine assessment of HER2 status in patients with advanced or recurrent mucinous ovarian carcinoma and highlights the potential of HER2-targeted therapy with trastuzumab in combination with standard carboplatin and paclitaxel in this disease. This case also raises the possibility that expansile mucinous ovarian carcinomas with ERBB2 amplification and p53 mutant immunohistochemical staining pattern (as this patient had) may be associated with a more aggressive behavior and higher risk of relapse.

ARTISTRY-7: phase III trial of nemvaleukin alfa plus pembrolizumab vs chemotherapy for platinum-resistant ovarian cancer.

Standard single-agent nonplatinum chemotherapy provides only modest benefit in a small proportion of patients with platinum-resistant/-refractory ovarian cancer, with objective response rates of 6-20% and progression-free survival of ≈3-4 months. Nemvaleukin alfa (nemvaleukin, ALKS 4230) is a novel cytokine designed to capture and expand the therapeutic potential of high-dose interleukin-2 (IL-2) while mitigating its associated toxicity issues. Nemvaleukin preferentially activates cytotoxic CD8+ T cells and natural killer cells with minimal, non-dose-dependent effects on CD4+ regulatory T cells. The global, randomized, open-label, phase III ARTISTRY-7 trial will compare efficacy and safety of nemvaleukin plus pembrolizumab with chemotherapy in patients with platinum-resistant ovarian cancer. The primary end point is investigator-assessed progression-free survival. Clinical Trial Registration: GOG-3063; ENGOT-OV68; NCT05092360 (ClinicalTrials.gov).

In many patients with ovarian cancer who are treated with platinum-based chemotherapy, the tumor comes back after a few months and fails to respond to repeated treatment. This type of disease is called platinum-resistant ovarian cancer (PROC). Researchers are searching for new medicines to help more patients with PROC. One treatment approach that has shown promise in different cancers is called immunotherapy. These medicines work by helping the body's immune system attack cancer cells. One of the immunotherapies being studied is called nemvaleukin. It is designed to trigger specific immune responses that may result in the immune system attacking cancer cells while potentially avoiding other immune responses that can block the attack or cause certain unwanted side effects. Nemvaleukin is being studied in a variety of cancer types. In a worldwide clinical trial called ARTISTRY-7, researchers are investigating how nemvaleukin works in patients with PROC when given with another immunotherapy called pembrolizumab. Patients who participate in this trial will be randomly assigned to one of four treatment groups: the combination of nemvaleukin and pembrolizumab, nemvaleukin by itself, pembrolizumab by itself, or a type of chemotherapy selected by the treating physician. The main purpose of ARTISTRY-7 is to understand whether the combination of nemvaleukin and pembrolizumab helps patients with PROC live longer without their cancer getting worse. At the time of this writing, ARTISTRY-7 is open for new patients to join.

Identification of BRCA1/2 mutation female carriers using circulating microRNA profiles.

Identifying germline BRCA1/2 mutation carriers is vital for reducing their risk of breast and ovarian cancer. To derive a serum miRNA-based diagnostic test we used samples from 653 healthy women from six international cohorts, including 350 (53.6%) with BRCA1/2 mutations and 303 (46.4%) BRCA1/2 wild-type. All individuals were cancer-free before and at least 12 months after sampling. RNA-sequencing followed by differential expression analysis identified 19 miRNAs significantly associated with BRCA mutations, 10 of which were ultimately used for classification: hsa-miR-20b-5p, hsa-miR-19b-3p, hsa-let-7b-5p, hsa-miR-320b, hsa-miR-139-3p, hsa-miR-30d-5p, hsa-miR-17-5p, hsa-miR-182-5p, hsa-miR-421, hsa-miR-375-3p. The final logistic regression model achieved area under the receiver operating characteristic curve 0.89 (95% CI: 0.87-0.93), 93.88% sensitivity and 80.72% specificity in an independent validation cohort. Mutated gene, menopausal status or having preemptive oophorectomy did not affect classification performance. Circulating microRNAs may be used to identify BRCA1/2 mutations in patients of high risk of cancer, offering an opportunity to reduce screening costs.

Dynamics of the DYNLL1/MRE11 complex regulates DNA end resection and recruitment of the Shieldin complex to DSBs.

Extent and efficacy of DNA end resection at DNA double strand break (DSB)s determines the choice of repair pathway. Here we describe how the 53BP1 associated protein DYNLL1 works in tandem with Shieldin and the CST complex to protect DNA ends. DYNLL1 is recruited to DSBs by 53BP1 where it limits end resection by binding and disrupting the MRE11 dimer. The Shieldin complex is recruited to a fraction of 53BP1-positive DSBs hours after DYNLL1 predominantly in the G1 cells. Shieldin localization to DSBs is dependent on MRE11 activity and is regulated by the interaction of DYNLL1 with MRE11. BRCA1-deficient cells rendered resistant to PARP inhibitors by the loss of Shieldin proteins can be re-sensitized by the constitutive association of DYNLL1 with MRE11. These results define the temporal and functional dynamics of the 53BP1-centric DNA end resection factors in cells.

STING agonism overcomes STAT3-mediated immunosuppression and adaptive resistance to PARP inhibition in ovarian cancer.

BACKGROUND: Poly (ADP-ribose) polymerase (PARP) inhibition (PARPi) has demonstrated potent therapeutic efficacy in patients with BRCA-mutant ovarian cancer. However, acquired resistance to PARPi remains a major challenge in the clinic. METHODS: PARPi-resistant ovarian cancer mouse models were generated by long-term treatment of olaparib in syngeneic Brca1-deficient ovarian tumors. Signal transducer and activator of transcription 3 (STAT3)-mediated immunosuppression was investigated in vitro by co-culture experiments and in vivo by analysis of immune cells in the tumor microenvironment (TME) of human and mouse PARPi-resistant tumors. Whole genome transcriptome analysis was performed to assess the antitumor immunomodulatory effect of STING (stimulator of interferon genes) agonists on myeloid cells in the TME of PARPi-resistant ovarian tumors. A STING agonist was used to overcome STAT3-mediated immunosuppression and acquired PARPi resistance in syngeneic and patient-derived xenografts models of ovarian cancer. RESULTS: In this study, we uncover an adaptive resistance mechanism to PARP inhibition mediated by tumor-associated macrophages (TAMs) in the TME. Markedly increased populations of protumor macrophages are found in BRCA-deficient ovarian tumors that rendered resistance to PARPi in both murine models and patients. Mechanistically, PARP inhibition elevates the STAT3 signaling pathway in tumor cells, which in turn promotes protumor polarization of TAMs. STAT3 ablation in tumor cells mitigates polarization of protumor macrophages and increases tumor-infiltrating T cells on PARP inhibition. These findings are corroborated in patient-derived, PARPi-resistant BRCA1-mutant ovarian tumors. Importantly, STING agonists reshape the immunosuppressive TME by reprogramming myeloid cells and overcome the TME-dependent adaptive resistance to PARPi in ovarian cancer. This effect is further enhanced by addition of the programmed cell death protein-1 blockade. CONCLUSIONS: We elucidate an adaptive immunosuppression mechanism rendering resistance to PARPi in BRCA1-mutant ovarian tumors. This is mediated by enrichment of protumor TAMs propelled by PARPi-induced STAT3 activation in tumor cells. We also provide a new strategy to reshape the immunosuppressive TME with STING agonists and overcome PARPi resistance in ovarian cancer.

Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: ASCO Endorsement of College of American Pathologists Guideline.

PURPOSE: The College of American Pathologists (CAP) has developed a guideline on testing for mismatch repair (MMR) and microsatellite instability (MSI) for patients considered for immune checkpoint inhibitor therapy. ASCO has a policy and set of procedures for endorsing clinical practice guidelines that have been developed by other professional organizations. METHODS: The CAP guideline was reviewed for developmental rigor by methodologists. An ASCO Endorsement Panel subsequently reviewed the content and the recommendations. RESULTS: The ASCO Endorsement Panel determined that the recommendations from the CAP guideline, published on August 3, 2022, are clear, thorough, and based on the most relevant scientific evidence. ASCO endorses Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: Guideline From the College of American Pathologists in Collaboration With the Association for Molecular Pathology and Fight Colorectal Cancer. RECOMMENDATIONS: Within the guideline, MMR immunohistochemistry (IHC), MSI polymerase chain reaction, and MSI next-generation sequencing are all recommended testing options for colorectal cancer, MMR-IHC and MSI-polymerase chain reaction for gastroesophageal and small bowel cancer, and only MMR-IHC for endometrial cancer. No recommendation in favor of any testing method over another could be made for any other cancer. Tumor mutational burden was not recommended as a surrogate for DNA MMR deficiency. If MMR deficiency consistent with Lynch syndrome is detected, it should be communicated to the treating physician.Additional information is available at www.asco.org/molecular-testing-and-biomarkers-guidelines.

Phase II Trials of Iniparib (BSI-201) in Combination with Gemcitabine and Carboplatin in Patients with Recurrent Ovarian Cancer.

BACKGROUND: Iniparib (BSI-201), a novel anticancer agent thought to have poly(ADP-ribose) polymerase (PARP) inhibitory activity and synergy with both gemcitabine and carboplatin (GC) was evaluated in 2 cohorts with GC. METHODS: Parallel multicenter, single-arm, phase II studies using a Simon two-stage design. Eligible patients had a histological diagnosis of epithelial ovarian carcinoma, fallopian tube cancer, or primary peritoneal carcinoma and demonstration of platinum-sensitive (≥6 months [mo]) or -resistant disease (relapse 2-6 mo post-platinum). Carboplatin (AUC 4 IV day 1), gemcitabine (1000 mg/m2 IV days 1 and 8), and iniparib (5.6 mg/kg IV days 1, 4, 8, and 11) were given on a 21-day cycle. RESULTS: The overall response rate (ORR RECIST 1.0) in platinum sensitive disease was 66% (95% CI, 49-80) with a higher response rate in the 15 pts with germline BRCA mutations (gBRCAmut) (73%). Median PFS was 9.9 (95% CI, 8.2-11.3) months. In the platinum resistant population the ORR was 26% (95% CI, 14-42), however in the 11 pts for whom BRCA mutation was present, the best overall response was PR in 5 (46%). Median PFS was 6.8 months (range, 5.7-7.7 months). Notably, among the 17 CA-125-response-evaluable patients who did not achieve tumor response, 7 (41.2%) patients had a CA125 response, and 93% has clinical benefit (CR + PR + SD). The GCI combination was generally well tolerated despite a high incidence of thrombocytopenia and neutropenia, with no new toxicities. CONCLUSIONS: Given the subsequent lack of efficacy demonstrated for iniparib in breast cancer, these are studies of GC and demonstrate a higher than traditionally appreciated activity in patients with platinum-sensitive and -resistant recurrent ovarian cancer, especially in patients that harbor a BRCA mutation, resetting the benchmark for efficacy in phase II trials. (ClinicalTrials.gov Identifiers: NCT01033292 & NCT01033123).

Targeting replication stress in cancer therapy.

Replication stress is a major cause of genomic instability and a crucial vulnerability of cancer cells. This vulnerability can be therapeutically targeted by inhibiting kinases that coordinate the DNA damage response with cell cycle control, including ATR, CHK1, WEE1 and MYT1 checkpoint kinases. In addition, inhibiting the DNA damage response releases DNA fragments into the cytoplasm, eliciting an innate immune response. Therefore, several ATR, CHK1, WEE1 and MYT1 inhibitors are undergoing clinical evaluation as monotherapies or in combination with chemotherapy, poly[ADP-ribose]polymerase (PARP) inhibitors, or immune checkpoint inhibitors to capitalize on high replication stress, overcome therapeutic resistance and promote effective antitumour immunity. Here, we review current and emerging approaches for targeting replication stress in cancer, from preclinical and biomarker development to clinical trial evaluation.

A Phase II, Two-Stage Study of Letrozole and Abemaciclib in Estrogen Receptor-Positive Recurrent Endometrial Cancer.

PURPOSE: Estrogen receptor (ER)-positive endometrial cancers (ECs) are characterized by phosphatidylinositol 3-kinase (PI3K) and receptor tyrosine kinase (RTK)/RAS/ß-catenin (CTNNB1) pathway alterations in approximately 90% and 80% of cases, respectively. Extensive cross-talk between ER, PI3K, and RTK/RAS/CTNNB1 pathways leads to both ligand-dependent and ligand-independent ER transcriptional activity as well as upregulation of cyclin D1 which, in complex with cyclin-dependent kinases 4 and 6 (CDK4 and CDK6), is a critical regulator of cell cycle progression and a key mediator of resistance to hormonal therapy. We hypothesized that the combination of the aromatase inhibitor letrozole and CDK4/6 inhibitor abemaciclib would demonstrate promising activity in this setting. METHODS: We conducted a phase II, two-stage study of letrozole/abemaciclib in recurrent ER-positive EC. Eligibility criteria included measurable disease, no limit on prior therapies, and all EC histologies; prior hormonal therapy was allowed. Primary end points were objective response rate by RECIST 1.1 and progression-free survival (PFS) rate at 6 months. RESULTS: At the data cutoff date (December 03, 2021), 30 patients (28 with endometrioid EC) initiated protocol therapy; 15 (50%) patients had prior hormonal therapy. There were nine total responses (eight confirmed), for an objective response rate of 30% (95% CI, 14.7 to 49.4), all in endometrioid adenocarcinomas. Median PFS was 9.1 months, PFS at 6 months was 55.6% (95% CI, 35.1 to 72), and median duration of response was 7.4 months. Most common ≥ grade 3 treatment-related adverse events were neutropenia (20%) and anemia (17%). Responses were observed regardless of grade, prior hormonal therapy, mismatch repair, and progesterone receptor status. Exploratory tumor profiling revealed several mechanistically relevant candidate predictors of response (CTNNB1, KRAS, and CDKN2A mutations) or absence of response (TP53 mutations), which require independent validation. CONCLUSION: Letrozole/abemaciclib demonstrated encouraging and durable evidence of activity in recurrent ER positive endometrioid EC.

Avelumab Plus Talazoparib in Patients With Advanced Solid Tumors: The JAVELIN PARP Medley Nonrandomized Controlled Trial.

Importance: Preclinical data suggest that poly(ADP-ribose) polymerase (PARP) inhibitors have synergistic activity when combined with immune checkpoint inhibitors (ICIs); however, it is unknown which tumor types or molecular subtypes may benefit from this combination. Objective: To investigate responses associated with the combination of avelumab and talazoparib in different tumor types and/or molecular subtypes. Design, Setting, and Participants: In this phase 1b and 2 basket nonrandomized controlled trial, patients with advanced solid tumors were enrolled in the following cohorts: non-small cell lung cancer (NSCLC); DNA damage response (DDR)-positive NSCLC; triple-negative breast cancer (TNBC); hormone receptor-positive, human epidermal growth factor receptor 2 (ERBB2)-negative, DDR-positive breast cancer; recurrent, platinum-sensitive ovarian cancer (OC); recurrent, platinum-sensitive, BRCA1/2-altered OC; urothelial cancer; metastatic castration-resistant prostate cancer (mCRPC); DDR-positive mCRPC; and BRCA1/2- or ATM-altered solid tumors. Data were analyzed between June 17, 2021, and August 6, 2021. Interventions: All patients in phases 1b and 2 received avelumab plus talazoparib. Main Outcomes and Measures: The phase 1b primary end point was dose-limiting toxic effects. The phase 2 primary end point was objective response, measured as objective response rate (ORR). Secondary end points included safety, time to response, duration of response (DOR), progression-free survival, time to prostate-specific antigen progression and PSA response of 50% or greater (for mCRPC), cancer antigen 125 response (for OC), pharmacokinetics, immunogenicity, and biomarkers. Results: A total of 223 patients (mean [SD] age, 63.2 [11.0] years; 117 [52.5%] men) were treated, including 12 patients in phase 1b and 211 patients in phase 2. The recommended phase 2 dose was avelumab 800 mg every 2 weeks plus talazoparib 1 mg once daily. In phase 2, the ORR was 18.2% (95% CI, 5.2%-40.3%) in patients with TNBC; 34.8% (95% CI, 16.4%-57.3%) in patients with HR-positive, ERBB2-negative, and DDR-positive BC; and 63.6% (95% CI, 30.8%-89.1%) in patients with platinum-sensitive, BRCA1/2-altered OC. Responses occurred more frequently in patients with BRCA1/2-altered tumors. Durable responses were observed in patients with TNBC (median [range] DOR, 11.1 [3.4-20.4] months); HR-positive, ERBB2-negative, and DDR-positive BC (median [range] DOR, 15.7 [3.9 to ≥20.6] months); and BRCA1/2-altered OC (median DOR not reached; range, 5.6 to ≥18.4 months). The most common grade 3 or greater treatment-related adverse events were anemia (75 patients [33.6%]), thrombocytopenia (48 patients [21.5%]), and neutropenia (31 patients [13.9%]). Conclusions and Relevance: This nonrandomized controlled trial found that ORRs for avelumab plus talazoparib were comparable with those with PARP inhibitor or ICI monotherapy. Prolonged DOR in patients with TNBC; HR-positive, ERBB2-negative, and DDR-positive BC; and BRCA1/2-altered OC warrant further investigation in randomized clinical trials. These data highlight the importance of prospective patient selection in future studies of ICI and PARP-inhibitor combinations. Trial Registration: ClinicalTrials.gov Identifier: NCT03330405.

Optimized detection of homologous recombination deficiency improves the prediction of clinical outcomes in cancer.

Homologous recombination DNA-repair deficiency (HRD) is a common driver of genomic instability and confers a therapeutic vulnerability in cancer. The accurate detection of somatic allelic imbalances (AIs) has been limited by methods focused on BRCA1/2 mutations and using mixtures of cancer types. Using pan-cancer data, we revealed distinct patterns of AIs in high-grade serous ovarian cancer (HGSC). We used machine learning and statistics to generate improved criteria to identify HRD in HGSC (ovaHRDscar). ovaHRDscar significantly predicted clinical outcomes in three independent patient cohorts with higher precision than previous methods. Characterization of 98 spatiotemporally distinct metastatic samples revealed low intra-patient variation and indicated the primary tumor as the preferred site for clinical sampling in HGSC. Further, our approach improved the prediction of clinical outcomes in triple-negative breast cancer (tnbcHRDscar), validated in two independent patient cohorts. In conclusion, our tumor-specific, systematic approach has the potential to improve patient selection for HR-targeted therapies.

A Phase 2 study of prexasertib (LY2606368) in platinum resistant or refractory recurrent ovarian cancer.

OBJECTIVE: High-grade serous ovarian cancer, the most frequent type of ovarian cancer, has a poor prognosis and novel treatments are needed for patients with platinum resistant/refractory disease. New therapeutic strategies targeting cell cycle checkpoints, including CHK1 inhibition with prexasertib, may help improve clinical response and overcome resistance. METHODS: Patients with ovarian cancer (N = 169) were assigned to 4 cohorts as part of the Phase 2 multicenter trial (NCT03414047): Cohort 1: platinum resistant, BRCA-wildtype with ≥3 lines prior therapy; Cohort 2: platinum resistant BRCA-wildtype with <3 lines prior therapy; Cohort 3: platinum resistant, BRCA-mutated with prior PARP inhibitor therapy; Cohort 4: platinum refractory, BRCA-mutated, or BRCA-wildtype with any number of prior therapy lines. The primary endpoint was objective response rate (ORR) and secondary endpoints included disease control rate (DCR), and safety. DNA from tumor biopsies was sequenced to identify biomarkers. RESULTS: The ORR in platinum resistant patients (Cohorts 1--3) was 12.1%, and 6.9% in platinum refractory patients. In platinum resistant patients, DCR was 37.1%, and consistent across cohorts. In platinum refractory patients, DCR was 31.0%. Consistent with the prexasertib mechanism of action, the most common treatment related adverse events of all grades included thrombocytopenia, neutropenia, fatigue, nausea, and anemia. CONCLUSIONS: Prexasertib demonstrated durable single agent activity in a subset of patients with recurrent ovarian cancer regardless of clinical characteristics, BRCA status, or prior therapies, including PARPi. There was no obvious correlation with genomic alterations in responders vs non-responders, emphasizing the need for alternative biomarker approaches for responder identification.