In the phase 2 OVARIO study, median progression-free survival (PFS) has not yet been reached in women with advanced ovarian cancer who are being treated with the combination of niraparib and bevacizumab after response to first-line platinum-based chemotherapy plus bevacizumab. The combination did not appear to cause cumulative toxicities.
In women with high-grade serous ovarian cancer who responded to first-line platinum-based chemotherapy plus bevacizumab, subsequent treatment with a combination of niraparib and bevacizumab induced an 89.5% 6-month PFS rate, according to an interim analysis of the phase 2 OVARIO study. Melissa M. Hardesty, MD, Gynecologic Medical Oncology Specialist, Alaska Women’s Cancer Care, Anchorage, reported at the 2020 Society of Gynecologic Oncology Annual Meeting on Women’s Cancer that the combination did not cause cumulative toxicities in the single-arm study.
The primary end point of OVARIO is PFS at 18 months from the start of treatment.
“As upfront maintenance therapy, our preliminary data suggest that niraparib in combination with bevacizumab is an effective combination to prolong PFS in all biomarker subgroups, consistent with the continuum of clinical benefit observed with monotherapy niraparib maintenance treatment in the PRIMA trial,” reported Dr Hardesty. She also noted that, although they are in a very high-risk population, 75% of women in the study were still progression-free at 12 months.
Advanced, high-grade serous ovarian cancer often recurs following primary therapy, generally within the first 1 to 2 years of follow-up. “The use of tolerable maintenance therapy to prevent or delay this recurrence has been a long sought-after goal,” Dr Hardesty said.
OVARIO includes 105 patients (median age, 60 years) with newly diagnosed International Federation of Gynecology and Obstetrics stage IIIB-IV ovarian cancer who had a complete response or partial response after first-line platinum-based chemotherapy plus bevacizumab. Results of tissue testing at enrollment showed that nearly half (47%) of patients had homologous recombination deficiency (HRD).
Patients were treated with bevacizumab 15 mg/kg every 3 weeks for up to 15 months. Niraparib was dosed at 300 or 200 mg once daily, based on baseline body weight and platelet count, starting within 12 weeks of completing first-line treatment and continued for 3 years or until progressive disease or unacceptable toxicity. The starting niraparib dosage was 200 mg in 78% of patients.
Sixty-three percent of patients received neoadjuvant chemotherapy and 21% of patients had stage IV disease. A partial response at the completion of primary therapy was reported in nearly 40% of patients.
The 12-month PFS rate was 75%, with median PFS still not reached. Patients with HRD had PFS rates of 98% at 6 months and 88% at 12 months.
The researchers reported no new safety signals. Dose interruptions and reductions were common, but only 25% led to treatment discontinuation.
“As has been shown previously with the combination of PARP and VEGF inhibition, the incidence of adverse events was high, with almost all patients experiencing some adverse events, and the majority having some grade ≥3 events,” said Dr Hardesty. The most common grade ≥3 treatment-related adverse events were thrombocytopenia, anemia, and hypertension, similar to that seen in the AVANOVA trial, which used the same drug combination, she noted.
Source: Hardesty MM, et al. Gynecol Oncol. 2020;159(1_suppl). Abstract 4.