MOONSTONE/GOG-3032: Interim analysis of a phase 2 study of niraparib + dostarlimab in patients (pts) with platinum-resistant ovarian cancer (PROC)

5573

Background: PROC is poorly responsive to anticancer therapy. PARP inhibitors such as niraparib may increase neoantigen load and synergize with anti-PD-1 agents. TOPACIO reported a preliminary objective response rate (ORR: 18%) and disease control rate (DCR: 65%) to niraparib + pembrolizumab in pts with OC of any BRCA status. MOONSTONE sought to determine efficacy in pts without BRCA mutation ( BRCAm). Methods: In this phase 2 open-label, single-arm study, eligible pts received 1–3 prior lines of therapy including platinum, taxane, and bevacizumab, had RECIST v1.1 radiographic progression within 6 mo of last platinum line and had no known germline BRCAm. Pts were treated with niraparib 300/200 mg PO daily (based on weight/platelets) and 500 mg dostarlimab IV Q3W (cycles 1–4) followed by 1000 mg Q6W until disease progression, toxicity or consent withdrawal. Programmed death-ligand 1 (PD-L1) positive status was determined by Ventana SP263 assay using visually-estimated combined positive score ≥5%. The primary endpoint was investigator-assessed ORR per RECIST v1.1. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), DCR, and safety. Futility was prespecified as ≤5 responses in the first 40 pts. Results: At interim analysis (data cutoff Oct 6, 2021), 41 pts were enrolled; median age was 65.0 y (range 35–77). At baseline, 8 (20%)/22 (54%)/11 (27%) pts had received 1/2/3 prior lines of therapy, respectively; 26 (63%) pts had primary resistance to platinum therapy and 15 (37%) were sensitive to first platinum treatment. Overall, tumors were PD-L1+/PD-L1–/unknown in 13 (32%)/25 (61%)/3 (7%), respectively. Efficacy results are shown in the Table. Treatment-related adverse events were reported in 95% of pts, most commonly nausea (56%), fatigue (34%), vomiting (32%), and anemia (29%). Conclusions: PROC remains difficult to treat; the ORR observed with niraparib + dostarlimab did not reach the threshold for 2nd-stage accrual in this cohort of pts with PROC, no known BRCAm, and prior bevacizumab treatment. PD-L1 status did not predict response; HRD testing is in process. Although DCR was 29%, futility was declared based on low ORR. The safety of the combination was similar to the safety profile of each monotherapy. Clinical trial information: NCT03955471. [Table: see text]

A phase III study comparing single-agent olaparib or the combination of cediranib and olaparib to standard platinum-based chemotherapy in recurrent platinum-sensitive ovarian cancer

6003

Background: Combination cediranib (C) and olaparib (O) improved progression-free survival (PFS) in patients (pts) with relapsed platinum (plat)-sensitive high-grade ovarian cancer (ovca) compared to O alone in a Phase 2 trial (NCT01116648). We conducted this randomized, open-label Phase 3 trial (NCT02446600) to assess whether combination C+O, or O alone, was superior to standard of care (SOC) plat-based therapy in relapsed plat-sensitive ovca. Methods: Eligible pts had recurrent plat-sensitive [ > 6-month plat-free interval (PFI)] high-grade serous or endometrioid, or BRCA-related, ovca. One prior non-plat therapy and unlimited prior plat-therapies were allowed; prior anti-angiogenics in the recurrent setting or prior PARP inhibitor were exclusions. Pts were randomized 1:1:1 to SOC (carboplatin/paclitaxel; carboplatin/gemcitabine; or carboplatin/liposomal doxorubicin), O (300mg twice daily), or C+O (C 30mg daily + O 200mg twice daily). Randomization was stratified by g BRCA status, PFI (6-12 vs > 12 months), and prior anti-angiogenic therapy. Target sample size was 549 pts; primary analysis occurred 2 years after the last pt enrolled. The primary endpoint was PFS. Type 1 error = 0.025 was controlled by a gatekeeping hierarchy that assessed C+O vs SOC, then O alone vs SOC, and finally C+O vs O. All maintenance therapy was prohibited. Results: Between 4FEB2016 and 13NOV2017, 565 pts enrolled (187 SOC, 189 O, 189 C+O), and 528 pts initiated treatment (166 SOC, 183 O, 179 C+O). 23.7% of patients had g BRCAmut. Median follow-up was 29.1 months. 53 pts on SOC initiated non-protocol therapy (predominantly PARP inhibitor maintenance) before disease progression. The hazard ratio (HR) for PFS was 0.856 (95% CI 0.66-1.11, p = 0.08, 1-tail) between C+O and SOC and 1.20 (95% CI 0.93-1.54) between O and SOC, with median PFS of 10.3, 8.2, and 10.4 months for SOC, O, and C+O, respectively. Response rates were 71.3% (SOC), 52.4% (O), and 69.4% (C+O). In gBRCA pts, HR for PFS was 0.55 (95% CI 0.73-1.30) for C+O vs SOC, and 0.63 (95% CI 0.37-1.07) for O vs SOC. In non-g BRCA pts, HR for these comparisons was 0.97 (95% CI 0.73-1.30) and 1.41 (1.07-1.86). No OS differences between arms were observed at 44% events. Pts receiving C+O (vs SOC) had more frequent Grade 3 or higher gastrointestinal (30.1% vs 8.4%), hypertension (31.7% vs 1.8%), and fatigue events (17.5% vs 1.8%). Conclusion: C+O demonstrated similar activity to SOC in relapsed plat-sensitive ovca but did not meet the primary endpoint of improved PFS. Clinical trial information: NCT02446600.

In vitro chemoresistance and biomarker profiles are unique for histologic subtypes of epithelial ovarian cancer

OBJECTIVES

To determine whether there is a relationship between histologic subtype of epithelial ovarian cancer and chemoresistance, we evaluated ovarian carcinomas of six histologic subtypes and correlated histology with in vitro drug response. Biomarker profiles (p53, Her-2 neu, and EGFR) were also evaluated to determine if their expression patterns were associated with histology.

METHODS

In vitro drug response profiles for different histologic subsets of epithelial ovarian carcinomas exposed to standard relevant chemotherapy agents were determined in the Extreme Drug Resistance assay (EDR). Immunohistochemistry techniques were employed to determine biomarker expression.

RESULTS

Of 5195 referred serial cases of epithelial ovarian cancer, there were 2660 papillary serous, 303 endometrioid, 142 mucinous, 102 clear cell, 952 undifferentiated carcinomas, and 42 tumors of low malignant potential. For the samples as a whole, the incidences of extreme drug resistance to the tested chemotherapeutic agents were cisplatin 10%, carboplatin 16%, cyclophosphamide 16%, doxorubicin 40%, gemcitabine 21%, paclitaxel 22%, and topotecan 13%. When compared to papillary serous tumors, mucinous tumors were more frequently resistant to cisplatin (10% vs. 18%) but less frequently resistant to topotecan (13% vs. 5%) and doxorubicin (42% vs. 16%). Endometrioid tumors were less resistant to cisplatin (10% vs. 6%) and doxorubicin (42% vs. 20%). Clear cell and undifferentiated tumors had the lowest rates of EDR to paclitaxel (13% and 18%) and cyclophosphamide (7% and 11%), while borderline tumors showed high rates of EDR to these agents (52% and 63%, respectively). With respect to biomarker profiles, mP53 was detected in 46%, Her-2 neu in 16%, and EGFR in 30% of the cases evaluated. As compared to all other subtypes, clear cell carcinomas had significantly higher Her-2 neu expression (19%). Relative to papillary serous carcinomas, borderline tumors exhibited significantly lower rates of mP53 expression (60% vs.17%).

CONCLUSIONS

We found significant differences in the frequencies of extreme drug resistance to chemotherapeutic agents and biomarker expression among histologic subtypes of epithelial ovarian cancer. The data collected in this investigation may provide a guide for stratification of patients entering clinical trials based on histology and biomarker expression.

Evaluation of D-methionine as a cytoprotectant in cisplatin treatment of an animal model for ovarian cancer

BACKGROUND

To evaluate the use of D-methionine(D-met) as a cytoprotectant in the context of clinically relevant doses of cisplatin.

MATERIALS AND METHODS

Forty five Fischer rats were injected intraperitoneally with 10(6) NuTu-19 cells and treated as follows: group 1 was the control group and received no treatment, group 2 received cisplatin 4 mg/kg and group 3 received cisplatin 4 mg/kg plus D-met. There were two groups that received high dose cisplatin. Group 4 received cisplatin 8 mg/kg and group 5 received cisplatin 8 mg/kg plus D-met. Treatment was initiated four weeks after injection of the NuTu-19 cells, and consisted of four weekly intraperitoneal injections. Serum BUN and creatinine levels in the high dose groups evaluated nephrotoxicity and clinical outcome was measured by mean survival using Kaplan Meier analysis.

RESULTS

There were no significant elevations in serum BUN or creatinine levels in any of the rats treated with high dose cisplatin. In the animals given cisplatin 8 mg/kg plus D-met, death from toxicity was prevented and all animals completed four treatments. In contrast, only two animals in group 4 (cisplatin 8 mg/kg alone) completed 4 treatments. There was a significant improvement in survival for the animals given D-met. (p = .0001) In all treated groups except for group 4, there was an improvement in survival compared to the control group. When comparing groups 2 and 3 (4 mg/kg +/- D-met), there was a subjective decrease in tumor response for group 3 but mean survival was not statistically different. (91 vs. 81 days; p = 0.07) A comparison of groups 2 and 5 revealed no survival benefit using high dose cisplatin with D-met. (91 vs. 79 days; p = 0.10).

CONCLUSIONS

Our results indicate that D-methionine provides cytoprotection against cisplatin toxicity without significant compromise of antitumor activity. All though D-methionine allowed for significant dose intensification of cisplatin above standard doses, there was no survival advantage noted in this group of animals. The indications for its use in the treatment of ovarian cancer remain to be determined.

Management of ovarian cancer in patients older than 80 years of Age

OBJECTIVE

The objective of this study was to examine the treatment, associated morbidity, and survival in very elderly patients with epithelial ovarian cancer.

METHODS

A retrospective analysis of patients 80 years of age and older treated for epithelial ovarian cancer by the Gynecologic Oncology faculty at the University of California Irvine was performed.

RESULTS

Eighteen patients were older than 80 years of age at the time of diagnosis of ovarian cancer. Median age was 83 years (range 80-86 years). There were 2 stage I, 10 stage IIIC, 4 stage VI, and 2 unstaged patients. One patient had a tumor of low malignant potential, 4 patients had grade II tumors, and 10 patients had tumors that were grade III. Eighty-three percent of patients had one or more preexisting medical illnesses. Cardiac disease, stroke, and hypertension were most common. Sixteen of 18 patients (88%) underwent primary debulking surgery. American Society of Anesthesiologists physical status classification was as follows: 7/16 (44%) class II, 6/16 (38%) class III, and 2/16 (13%) class IV. The procedures performed included 16 bilateral salpingo-oophorectomies, 11 total abdominal hysterectomies, 16 omentectomies, 3 lymph node dissections, and 7 bowel resections. Four (25%) patients were optimally cytoreduced to <1 cm of residual disease. Seventy-five percent of surgical patients received blood transfusions of 2 or more units PRBC. Mean EBL was 600 cc (range 200-4200 cc). Thirty-eight percent of patients experienced major postoperative morbidity. There were 7 patients with postoperative congestive heart failure, 3 with sepsis, 1 with aspiration pneumonia, and 2 postoperative deaths. Seventy-five percent of patients spent time in the intensive care unit. Median number of days was 3 (range 1-22 days). Mean postoperative stay was 8 days (range 6-57 days). Sixty-five percent of patients were discharged to home. The other patients were discharged to intermediate care facilities or nursing homes. Eighty-three percent of patients received chemotherapy. Of the 10 patients (63%) receiving adjuvant chemotherapy, the mean interval from surgery to initiation of therapy was 3 weeks (range 1-4 weeks). Overall median survival was 6 months (range 1-45 months). Median survival in patients with optimal debulking was 32.5 months (range 7-45 months) compared to 3.5 months (range 1-41 months) in patients suboptimally debulked.

CONCLUSIONS

In patients older than 80 years of age who undergo debulking surgery for ovarian cancer, serious medical comorbidity and advanced ASA status are common. Despite aggressive surgical effort and frequent blood transfusions, optimal debulking to less than 1 cm is achieved in only 25% of patients. Impressive morbidity and mortality occurs in this group of patients, but most patients are discharged to home and are able to receive postoperative chemotherapy.