RAS (KRAS, NRAS and HRAS) is the most frequently mutated gene family in cancers, and, consequently, investigators have sought an effective RAS inhibitor for more than three decades. Even 10 years ago, RAS inhibitors were so elusive that RAS was termed ‘undruggable’. Now, with the success of allele-specific covalent inhibitors against the most frequently mutated version of RAS in non-small-cell lung cancer, KRASG12C, we have the opportunity to evaluate the best therapeutic strategies to treat RAS-driven cancers. Mutation-specific biochemical properties, as well as the tissue of origin, are likely to affect the effectiveness of such treatments. Currently, direct inhibition of mutant RAS through allele-specific inhibitors provides the best therapeutic approach. Therapies that target RAS-activating pathways or RAS effector pathways could be combined with these direct RAS inhibitors, immune checkpoint inhibitors or T cell-targeting approaches to treat RAS-mutant tumours. Here we review recent advances in therapies that target mutant RAS proteins and discuss the future challenges of these therapies, including combination strategies. RAS proteins, which are frequently altered in cancer, were once considered undruggable, but compounds targeting some mutant RAS proteins have recently demonstrated clinical efficacy. In this Review, Malek and colleagues explore how these and other drugs that target RAS or associated pathways might be used effectively, particularly in combinations, and discuss other RAS-targeted therapies in the pipeline.

RAS-targeted therapies: is the undruggable drugged?

PURPOSESingle-agent PD-1 blockade exhibits limited efficacy in epithelial ovarian cancer (EOC). We evaluated ipilimumab plus nivolumab compared with nivolumab alone in women with persistent or recu...

https://ascopubs.org/doi/pdf/10.1200/JCO.19.02059

Randomized Phase II Trial of Nivolumab Versus Nivolumab and Ipilimumab for Recurrent or Persistent Ovarian Cancer: An NRG Oncology Study

Combined PARP and immune checkpoint inhibition has yielded encouraging results in ovarian cancer, but predictive biomarkers are lacking. We performed immunogenomic profiling and highly multiplexed single-cell imaging on tumor samples from patients enrolled in a Phase I/II trial of niraparib and pembrolizumab in ovarian cancer (NCT02657889). We identify two determinants of response; mutational signature 3 reflecting defective homologous recombination DNA repair, and positive immune score as a surrogate of interferon-primed exhausted CD8 + T-cells in the tumor microenvironment. Presence of one or both features associates with an improved outcome while concurrent absence yields no responses. Single-cell spatial analysis reveals prominent interactions of exhausted CD8 + T-cells and PD-L1 + macrophages and PD-L1 + tumor cells as mechanistic determinants of response. Furthermore, spatial analysis of two extreme responders shows differential clustering of exhausted CD8 + T-cells with PD-L1 + macrophages in the first, and exhausted CD8 + T-cells with cancer cells harboring genomic PD-L1 and PD-L2 amplification in the second. A Phase I/II trial previously revealed variable anti-tumor efficacy of the PARP inhibitor niraparib in combination with the PD-1 inhibitor pembrolizumab in platinum-resistant ovarian cancer patients. Here, the authors perform an integrated genomic and immunomics analysis of tumor samples from the same patients and find potential predictive biomarkers of response to such combination therapy.

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Immunogenomic profiling determines responses to combined PARP and PD-1 inhibition in ovarian cancer.

Importance To date, single-agent programmed cell death 1 protein 1 (PD-1)/programmed death ligand 1 (PD-L1) immune checkpoint blockade has shown limited activity in recurrent epithelial ovarian cancer. Combination strategies of PD-1/PD-L1 inhibition with antiangiogenic therapy have the potential for synergistic activity through modulation of the microenvironment and represent a potential therapeutic opportunity in this disease. Objective To evaluate the activity of combined nivolumab and bevacizumab in women with relapsed ovarian cancer. Design, Setting, and Participants A single-arm, phase 2 study enrolled patients between February 8, 2017, and December 29, 2017, at 2 sites in the United States; the primary data analysis was completed July 27, 2018. Thirty-eight women with relapsed epithelial ovarian cancer were enrolled in this study. Participants had disease recurrence within 12 months of their last platinum-based therapy and had received between 1 and 3 lines of prior therapy. Interventions Participants received intravenous nivolumab and intravenous bevacizumab once every 2 weeks. Main Outcome and Measures The primary end point was objective response rate (ORR) as measured by Response Evaluation Criteria in Solid Tumors 1.1. Secondary end points included evaluation of the ORR by platinum sensitivity, assessment of progression-free survival, assessment of safety data, and investigation of the association of tumor PD-L1 with response to therapy. Results Of the 38 women enrolled, 18 had platinum-resistant and 20 had platinum-sensitive disease; mean (SD) age was 63.0 (9.1) years. Eleven patients experienced a confirmed response to nivolumab with bevacizumab (ORR, 28.9%; 95% exact binomial CI, 15.4%-45.9%), with 1 additional unconfirmed response. The ORR was 40.0% (19.1%-64.0%) in platinum-sensitive and 16.7% (95% CI 3.6%-41.4%) in platinum-resistant participants. Thirty-four participants (89.5%) experienced at least 1 treatment-related adverse event; 9 participants (23.7%) experienced a grade 3 or higher treatment-related adverse event. Median progression-free survival was 8.1 months (95% CI, 6.3-14.7 months). In 36 histologic samples for which PD-L1 testing could be performed, 22 samples (61.1%) had a PD-L1 tumoral percentage less than 1, and 14 samples (38.9%) had a PD-L1 tumoral percentage of 1 or greater. Ten responses occurred in patients with PD-L1 tumor percentage less than 1, and 2 in patients with PD-L1 tumor percentages of 1 or greater. Conclusions and Relevance The nivolumab with bevacizumab combination appeared to show activity in patients with relapsed ovarian cancer, with greater activity in the platinum-sensitive setting. Alternative combinational strategies may be necessary in the platinum-resistant setting.

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Assessment of Combined Nivolumab and Bevacizumab in Relapsed Ovarian Cancer: A Phase 2 Clinical Trial

PURPOSEDespite the tissue-agnostic approval of pembrolizumab in mismatch repair deficient (MMRD) solid tumors, important unanswered questions remain about the role of immune checkpoint blockade in ...

https://ascopubs.org/doi/pdf/10.1200/JCO.19.01021

Phase II Study of Avelumab in Patients With Mismatch Repair Deficient and Mismatch Repair Proficient Recurrent/Persistent Endometrial Cancer.

Importance Current treatment options for progressive ovarian cancer provide limited benefit, particularly in patients whose disease has become resistant to platinum-based chemotherapy. Objective To assess the efficacy and safety of avelumab, an anti–programmed death-ligand 1 agent, in a cohort of patients with previously treated recurrent or refractory ovarian cancer. Design, Setting, and Participants In an expansion cohort of a phase 1b, open-label study (JAVELIN Solid Tumor), 125 patients with advanced ovarian cancer who had received chemotherapy including a platinum agent were enrolled between November 6, 2013, and August 27, 2015. Statistical analysis was performed from December 31, 2016, to October 9, 2018. Intervention Patients received avelumab, 10 mg/kg, every 2 weeks until disease progression, unacceptable toxic effects, or withdrawal from the study. Main Outcomes and Measures Prespecified end points in this cohort included confirmed best overall response (per Response Evaluation Criteria In Solid Tumors, version 1.1), immune-related best overall response, duration of response, progression-free survival, overall survival, results of programmed death-ligand 1 expression–based analyses, and safety. Results A total of 125 women (median age, 62.0 years [range, 27-84 years]) who had received a median of 3 prior lines of treatment (range, 0-10) for advanced disease were enrolled in the study. Patients received avelumab for a median of 2.8 months (range, 0.5-27.4 months), with a median follow-up of 26.6 months (range, 16-38 months). A confirmed objective response occurred in 12 patients (9.6%; 95% CI, 5.1%-16.2%), including a complete response in 1 patient (0.8%) and a partial response in 11 patients (8.8%). The 1-year progression-free survival rate was 10.2% (95% CI, 5.4%-16.7%) and median overall survival was 11.2 months (95% CI, 8.7-15.4 months). Infusion-related reactions occurred in 25 patients (20.0%). Other frequent treatment-related adverse events (any grade event occurring in ≥10% of patients) were fatigue (17 [13.6%]), diarrhea (15 [12.0%]), and nausea (14 [11.2%]). Grade 3 or higher treatment-related adverse events occurred in 9 patients (7.2%), of which only the level of lipase increased (3 [2.4%]) occurred in more than 1 patient. Twenty-one patients (16.8%) had an immune-related adverse event of any grade. No treatment-related deaths occurred. Conclusions and Relevance Avelumab demonstrated antitumor activity and acceptable safety in heavily pretreated patients with recurrent or refractory ovarian cancer. Trial Registration ClinicalTrials.gov identifier:NCT01772004

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Kathleen M. Moore

Papers

Efficacy and Safety of Avelumab for Patients With Recurrent or Refractory Ovarian Cancer: Phase 1b Results From the JAVELIN Solid Tumor Trial.