Safety: MDS/AML
Hematologic treatment-emergent adverse events occurred primarily in the first year of niraparib treatment. The incidence of grade 3 or greater thrombocytopenia decreased from 33.8% at 1 year to 2.8% in years 2-3. The incidence of anemia decreased from 25.6% to 0.7%, and the neutropenia incidence decreased from 19.3% to 2.1%.
At last follow-up, 13 patients in the niraparib arm (3.5%) and 3 in the placebo arm (1.7%) had developed myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML).
The incidence of MDS/AML was 6.6% among patients with germline BRCA mutations who received niraparib, noted invited discussant Deborah K. Armstrong, MD, of the Johns Hopkins Kimmel Cancer Center in Baltimore.
That incidence was nearly as high as the 8% incidence of MDS/AML seen among similar patients in the SOLO-2 trial of olaparib maintenance, she noted.
This observation raises the question “of whether more extensive prior therapy or the longer duration of PARP inhibitor therapy in patients who have recurrent platinum-sensitive disease is the biggest contributor to that,” she said.
Dr. Armstrong commented that it remains to be seen whether the incidence of MDS/AML will increase with longer follow-up, particularly among patients who were more heavily pretreated with chemotherapy prior to PARP inhibitor maintenance, and in patients who remain on a PARP inhibitor until progression in ongoing trials of PARP inhibitors as frontline therapy.
The ENGOT-OV16/NOVA trial was funded by GlaxoSmithKline. Dr. Matulonis reported consulting/advisory fees from Merck, Novartis, and NextCure. Dr. Armstrong disclosed relationships with several companies, not including GlaxoSmithKline.