Fiona Simpkins

Olaparib as treatment for platinum‐sensitive relapsed ovarian cancer by BRCA mutation and homologous recombination deficiency: Phase 2 LIGHT study final overall survival analysis

AbstractBackgroundLIGHT (oLaparib In HRD‐Grouped Tumor types; NCT02983799) prospectively evaluated olaparib treatment in patients with platinum‐sensitive relapsed ovarian cancer (PSROC) assigned to cohorts by known BRCA mutation (BRCAm) and homologous recombination deficiency (HRD) status: germline BRCAm (gBRCAm), somatic BRCAm (sBRCAm), HRD‐positive non‐BRCAm, and HRD‐negative. At the primary analysis, olaparib treatment demonstrated activity across all cohorts, with greatest efficacy in terms of objective response rate and progression‐free survival observed in the g/sBRCAm cohorts. The authors report final overall survival (OS).MethodsIn this phase 2, open‐label, noncomparative study, patients with PSROC and one or more prior line of platinum‐based chemotherapy were assigned to cohorts by BRCAm and HRD status. OS was a secondary end point. Tumors were analyzed using Myriad BRACAnalysis CDx and MyChoice CDx assays; HRD‐positive tumors were defined using a genomic instability score of ≥42.ResultsOf 272 enrolled patients, 271 received olaparib and 270 met the inclusion criteria for the efficacy analysis. At data cutoff, 18‐month OS rates in the gBRCAm, sBRCAm, HRD‐positive non‐BRCAm, and HRD‐negative cohorts were 86.4%, 88.0%, 78.6%, and 59.6%, respectively. No new safety signals were observed. In a post hoc analysis, patients on treatment for >18 months were most frequently present in g/sBRCAm cohorts (31.0%).ConclusionsOlaparib treatment continued to demonstrate benefit across all cohorts. Consistent with the primary analysis, the highest OS rates were observed in the BRCAm cohorts, regardless of g/sBRCAm. In patients without a BRCAm, a higher OS rate was observed in the HRD‐positive non‐BRCAm than the HRD‐negative cohorts. These results highlight the importance of biomarker testing in this treatment setting.

C ombination A TR (ceralasertib) and P A R P (olaparib) I nhibitor (CAPRI) Trial in Acquired PARP Inhibitor–Resistant Homologous Recombination–Deficient Ovarian Cancer

Abstract Purpose: Addition of ataxia telangiectasia and Rad3-related kinase inhibitors (ATRi) to PARP inhibitors (PARPi) overcomes PARPi resistance in high-grade serous ovarian cancer (HGSOC) cell and mouse models. We present the results of an investigator-initiated study of combination PARPi (olaparib) and ATRi (ceralasertib) in patients with acquired PARPi-resistant HGSOC. Patients and Methods: Eligible patients had recurrent, platinum-sensitive BRCA1/2 mutated or homologous recombination (HR)–deficient (HRD) HGSOC and clinically benefited from PARPi (response by imaging/CA-125 or duration of maintenance therapy; > 12 months first-line or > 6 months ≥ second-line) before progression. No intervening chemotherapy was permitted. Patients received olaparib 300 mg twice daily and ceralasertib 160 mg daily on days 1 to 7 of a 28-day cycle. Primary objectives were safety and objective response rate (ORR). Results: Thirteen patients enrolled were evaluable for safety and 12 for efficacy; 62% (n = 8) had germline BRCA1/2 mutations, 23% (n = 3) somatic BRCA1/2 mutations, and 15% (n = 2) tumors with positive HRD assay. Prior PARPi indication was treatment for recurrence (54%, n = 7), second-line maintenance (38%, n = 5) and first-line treatment with carboplatin/paclitaxel (8%, n = 1). There were 6 partial responses yielding an ORR of 50% (95% confidence interval, 0.15–0.72). Median treatment duration was 8 cycles (range 4–23+). Grade (G) 3/4 toxicities were 38% (n = 5); 15% (n = 2) G3 anemia, 23% (n = 3) G3 thrombocytopenia, 8% (n = 1) G4 neutropenia. Four patients required dose reductions. No patient discontinued treatment due to toxicity. Conclusions: Combination olaparib and ceralasertib is tolerable and shows activity in HR-deficient platinum-sensitive recurrent HGSOC that benefited and then progressed with PARPi as the penultimate regimen. These data suggest that ceralasertib resensitizes PARPi-resistant HGSOCs to olaparib, warranting further investigation.

Ovarian granulosa cell tumor characterization identifies FOXL2 as an immunotherapeutic target

Granulosa cell tumors (GCT) are rare ovarian malignancies. Due to the lack of effective treatment in late relapse, there is a clear unmet need for novel therapies. Forkhead Box L2 (FOXL2) is a protein mainly expressed in granulosa cells (GC) and therefore is a rational therapeutic target. Since we identified tumor infiltrating lymphocytes (TILs) as the main immune population within GCT, TILs from 11 GCT patients were expanded, and their phenotypes were interrogated to determine that T cells acquired late antigen-experienced phenotypes and lower levels of PD1 expression. Importantly, TILs maintained their functionality after ex vivo expansion as they vigorously reacted against autologous tumors (100% of patients) and against FOXL2 peptides (57.1% of patients). To validate the relevance of FOXL2 as a target for immune therapy, we developed a plasmid DNA vaccine (FoxL2-tetanus toxin; FoxL2-TT) by fusing Foxl2 cDNA with the immune-enhancing domain of TT. Mice immunization with FoxL2-TT controlled growth of FOXL2-expressing ovarian (BR5) and breast (4T1) cancers in a T cell-mediated manner. Combination of anti-PD-L1 with FoxL2-TT vaccination further reduced tumor progression and improved mouse survival without affecting the female reproductive system and pregnancy. Together, our results suggest that FOXL2 immune targeting can produce substantial long-term clinical benefits. Our study can serve as a foundation for trials testing immunotherapeutic approaches in patients with ovarian GCT.

Combining PARP with ATR inhibition overcomes PARP inhibitor and platinum resistance in ovarian cancer models

AbstractOvarian cancer (OVCA) inevitably acquires resistance to platinum chemotherapy and PARP inhibitors (PARPi). We show that acquisition of PARPi-resistance is accompanied by increased ATR-CHK1 activity and sensitivity to ATR inhibition (ATRi). However, PARPi-resistant cells are remarkably more sensitive to ATRi when combined with PARPi (PARPi-ATRi). Sensitivity to PARPi-ATRi in diverse PARPi and platinum-resistant models, including BRCA1/2 reversion and CCNE1-amplified models, correlate with synergistic increases in replication fork stalling, double-strand breaks, and apoptosis. Surprisingly, BRCA reversion mutations and an ability to form RAD51 foci are frequently not observed in models of acquired PARPi-resistance, suggesting the existence of alternative resistance mechanisms. However, regardless of the mechanisms of resistance, complete and durable therapeutic responses to PARPi-ATRi that significantly increase survival are observed in clinically relevant platinum and acquired PARPi-resistant patient-derived xenografts (PDXs) models. These findings indicate that PARPi-ATRi is a highly promising strategy for OVCAs that acquire resistance to PARPi and platinum.

Phase 1 trial of nelfinavir added to standard cisplatin chemotherapy with concurrent pelvic radiation for locally advanced cervical cancer

BackgroundNelfinavir (NFV), an HIV‐1 protease inhibitor, has been shown to sensitize cancer cells to chemoradiation (CRT). The objectives of this phase 1 trial were to evaluate safety and identify the recommended phase 2 dose of NFV added to concurrent CRT for locally advanced cervical cancer.MethodsTwo dose levels of NFV were evaluated: 875 mg orally twice daily (dose level 1 [DL1]) and 1250 mg twice daily (DL2). NFV was initiated 7 days before CRT and continued through CRT completion. Toxicity, radiographic responses, and pathologic responses were evaluated. Serial tumor biopsies (baseline, after NFV monotherapy, on NFV + CRT, and posttreatment) were evaluated by immunohistochemistry, NanoString, and reverse‐phase‐protein‐array analyses.ResultsNFV sensitized cervical cancer cells to radiation, increasing apoptosis and tumor suppression in vivo. Patients (n = 13) with International Federation of Gynecology and Obstetrics stage IIA through IVA squamous cell cervical carcinoma were enrolled, including 7 patients at DL1 and 6 patients at DL2. At DL1, expansion to 6 patients was required after a patient developed a dose‐limiting toxicity, whereas no dose‐limiting toxicities occurred at DL2. Therefore, DL2 was established as the recommended phase 2 dose. All patients at DL2 completed CRT, and 1 of 6 experienced grade 3 or 4 anemia, nausea, and diarrhea. One recurrence was noted at DL2, with disease outside the radiation field. Ten of 11 evaluable patients remained without evidence of disease at a median follow‐up of 50 months. NFV significantly decreased phosphorylated Akt levels in tumors. Cell cycle and cancer pathways also were reduced by NFV and CRT.ConclusionsNFV with CRT is well tolerated. The response rate is promising compared with historic controls in this patient population and warrants further investigation.

Targeting CCNE1 amplified ovarian and endometrial cancers by combined inhibition of PKMYT1 and ATR

Abstract Ovarian cancers (OVCAs) and endometrial cancers (EMCAs) with CCNE1- amplification are often resistant to standard treatment and represent an unmet clinical need. Synthetic-lethal screening identified loss of the CDK1 regulator, PKMYT1, as synthetically lethal with CCNE1 -amplification. We hypothesize that CCNE1 -amplification associated replication stress will be more effectively targeted by combining PKMYT1 inhibitor lunresertib (RP-6306), with ATR inhibitor camonsertib (RP-3500/RG6526). Low dose combination RP-6306 with RP-3500 synergistically increases cytotoxicity more so in CCNE1 -amplified compared to non-amplified cells. Combination treatment produces durable antitumor activity, reduces metastasis and increases survival in CCNE1 -amplified patient-derived OVCA and EMCA xenografts. Mechanistically, low doses of RP-6306 with RP-3500 increase CDK1 activation more so than monotherapy, triggering rapid and robust induction of premature mitosis, DNA damage, and apoptosis in a CCNE1 -dependent manner. These findings suggest that targeting CDK1 activity by combining RP-6306 with RP-3500 is an effective therapeutic approach to treat CCNE1 -amplifed OVCAs and EMCAs.

A B7-H4–Targeting Antibody–Drug Conjugate Shows Antitumor Activity in PARPi and Platinum-Resistant Cancers with B7-H4 Expression

Abstract Purpose: Platinum and PARP inhibitors (PARPi) demonstrate activity in breast and ovarian cancers, but drug resistance ultimately emerges. Here, we examine B7-H4 expression in primary and recurrent high-grade serous ovarian carcinoma (HGSOC) and the activity of a B7-H4-directed antibody–drug conjugate (B7-H4-ADC), using a pyrrolobenzodiazepine-dimer payload, in PARPi- and platinum-resistant HGSOC patient-derived xenograft (PDX) models. Experimental Design: B7-H4 expression was quantified by flow cytometry and IHC. B7-H4-ADC efficacy was tested against multiple cell lines in vitro and PDX in vivo. The effect of B7-H4-ADC on cell cycle, DNA damage, and apoptosis was measured using flow cytometry. Results: B7-H4 is overexpressed in 92% of HGSOC tumors at diagnosis (n = 12), persisted in recurrent matched samples after platinum treatment, and was expressed at similar levels across metastatic sites after acquired multi-drug resistance (n = 4). Treatment with B7-H4-ADC resulted in target-specific growth inhibition of multiple ovarian and breast cancer cell lines. In platinum- or PARPi-resistant ovarian cancer cells, B7-H4-ADC significantly decreased viability and colony formation while increasing cell-cycle arrest and DNA damage, ultimately leading to apoptosis. Single-dose B7-H4-ADC led to tumor regression in 65.5% of breast and ovarian PDX models (n = 29), with reduced activity in B7-H4 low or negative models. In PARPi and platinum-resistant HGSOC PDX models, scheduled B7-H4-ADC dosing led to sustained tumor regression and increased survival. Conclusions: These data support B7-H4 as an attractive ADC target for treatment of drug-resistant HGSOC and provide evidence for activity of an ADC with a DNA-damaging payload in this population. See related commentary by Veneziani et al., p. 1434