2018 SGO Annual Meeting Highlights

Results from a phase I/II trial presented at the meeting held in New Orleans, Louisiana, showed that patients with platinum-resistant/refractory ovarian cancer had durable responses to the combination of niraparib and pembrolizumab.

Overall, 15 of 60 evaluable patients had objective responses, and the combination achieved disease control in 68% of the cohort. A subgroup analysis showed consistent activity across biomarker-selected groups. Additionally, the safety was consistent with the profiles of the individual drugs, and no new or unexpected toxicities occurred.

Phase I of the trial included 9 patients and resulted in recommended phase II doses of 200 mg of niraparib daily and 200 mg every 3 weeks of pembrolizumab. During the phase II portion, investigators enrolled an additional 53 patients, 2 of whom discontinued after less than 9 weeks and did not have post-baseline scans. Investigators acquired comprehensive biomarker data for 83% of the patients.

In an analysis of 46 biomarker-selected patients, the combination led to objective responses in 2 of 7 patients with BRCA mutations, 4 of 15 who were HRD positive, 9 of 34 who had BRCA wild-type tumors, and 7 of 24 who were HRD negative.

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Patients with HER2-positive uterine serous carcinoma had a greater than 50% improvement in progression-free survival when treated with trastuzumab and chemotherapy versus chemotherapy alone, according to findings of a small randomized trial presented at the meeting.

Data showed that the median PFS increased from 8.0 months with carboplatin and paclitaxel to 12.6 months with the addition of trastuzumab to the same chemotherapy regimen. Patients with more advanced disease had almost a twofold increase in median PFS from 9.3 months with chemotherapy versus 17.9 months with the trastuzumab combination.

A preliminary survival analysis showed a trend in favor of the trastuzumab arm, which appeared to increase for patients with more advanced-stage disease and those who received the combination as initial systemic therapy.

Moreover, an analysis of all 58 evaluable patients showed that the addition of trastuzumab reduced the hazard ratio for progression or death by 56%. The small group of patients with recurrent disease also benefited from trastuzumab, as the median PFS was 9.2 months with the anti-HER2 drug and 6.0 months for chemotherapy alone.

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An analysis of the phase III ENGOT-OV16/NOVA study showed that baseline body weight and platelet counts were found to be early predictors for future adverse event-related dose modifications for niraparib in women with platinum-sensitive, relapsed, high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancer.

The retrospective analysis showed that just 17% of patients with body weight less than 77 kg or platelet counts less than 150,000 per microliter could remain at the 300-mg starting dose. Additionally, a greater incidence of grade 3/4 treatment-emergent AEs in this group resulted in dose reduction or treatment discontinuation for niraparib.

Overall, patients less than 58 kg had greater incidence of grade 3 or higher treatment-emergent adverse events compared with patients greater than or equal to 77 kg.

Of those with a baseline platelet count of less than 180,000 at baseline, 42% had a grade 3/4 thrombocytopenia event versus 25% for those with counts between 180,000 and 215,000, 31% for those between 215,000 and 273,000, and 20% for those with counts greater than or equal to 273,000.

Moreover, in an analysis completed from 4 months and beyond, no difference was seen in progression-free survival between the 300-mg and the 200-mg dose. Nor were any seen between the 300-mg and the 100-mg doses.

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Initial findings of a study presented at the SGO meeting demonstrated that nearly half of patients with platinum-resistant ovarian cancer had objective responses to combination therapy with pembrolizumab mirvetuximab soravtansine.

Results showed that 6 of 14 patients had confirmed partial responses to the PD-1 inhibitor and the antifolate antibody-drug conjugate. Five of 8 patients who had moderate-to-high levels of folate receptor-alpha expression had responses.

The median progression-free survival was 5.2 months in the entire cohort and 8.6 months in the moderate-to-high cohort. The median duration of response was 30.1 weeks overall and 36.1 weeks in the patients with medium to high folate receptor-alpha expression.

The results supported continued investigation of the combination, which is ongoing in an expansion phase that will accrue an additional 35 patients with moderate-to-high expression of folate receptor-alpha. A phase III trial of mirvetuximab soravtansine for those with platinum-resistant disease also is ongoing.

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Finally, results of the phase II MEDIOLA trial showed that combination treatment with the PARP inhibitor olaparib plus the PD-L1 inhibitor durvalumab led to a 72% overall response rate in patients with relapsed, platinum-sensitive, BRCA-mutant ovarian cancer.

Twenty-three of 32 patients had objective responses with olaparib plus durvalumab, including 6 complete responses and 17 partial responses. A subgroup analysis showed a consistency of response in patients who had received as many as 3 prior lines of therapy. The regimen was also found to be well tolerated.

Additional data showed that the combination achieved a 12-week disease-control rate of 81%. An additional 3 patients had stable disease, bringing the disease control rate to 81%. Three patients had progressive disease.

Future evaluation of the combination will include expansion of the BRCA-mutant cohort to a total 100 patients. A patient cohort with relapsed BRCA wild-type tumors will also receive the combination. And, a global phase III trial of the combination as first-line therapy in ovarian cancer is expected to begin by the end of the second quarter of 2018.

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That’s all for today.

Thank you for watching OncLive News Network! I’m Gina Columbus.