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Risk of Secondary Hematologic Malignancy Not Significantly Increased by PARP Inhibitors

2020 Year in Review - Ovarian Cancer

Although researchers noted a trend toward increased incidence of secondary hematologic malignancy in patients with newly diagnosed ovarian cancer treated with poly (ADP-ribose) polymerase (PARP) inhibitors, the difference was not statistically significant.

In women with advanced ovarian cancer who are treated with PARP inhibitor maintenance or as first-line treatment, the risk of secondary hematologic malignancies is not increased significantly. In a combined meta-analysis of 7 phase 3 randomized controlled trials of women with advanced ovarian cancer, the overall incidence of secondary hematologic malignancies was 0.80% in the women randomized to PARP inhibitors as maintenance compared with 0.47% in controls (risk ratio [RR], 1.45; 95% confidence interval [CI], 0.68-3.07; P = .34). Data were reported by Thura W. Htut, MBBS, MRCP, Haematology Fellow, Aberdeen Royal Infirmary, Scotland, UK, and colleagues in poster format at this year’s virtual scientific program of the American Society of Clinical Oncology.

A total of 4445 patients were included from the ARIEL3, ENGOT-OV16/NOVA, and SOLO-2 clinical trials in which PARP inhibitors were studied in the treatment of recurrent ovarian cancer, and the VELIA, PRIMA, SOLO-1, and PAOLA-1 clinical trials in which PARP inhibitors were studied as first-line treatment. In the study arm, treatment regimens were olaparib, niraparib, rucaparib, veliparib, or olaparib plus bevacizumab. The control arm consisted of placebo or bevacizumab. Randomization was 2:1 in all studies.

The incidence of a secondary hematologic malignancy in patients with newly diagnosed ovarian cancer (N = 3044) was 0.59% in the group randomized to PARP inhibitors compared with 0.09% in the control group. The difference was not statistically significant (RR, 2.7; 95% CI, 0.7-10.37; P = .15) despite a numeric trend toward increased incidence in patients receiving PARP inhibitors.

The secondary hematologic malignancy rate in women with recurrent ovarian cancer (N = 1401) was identical (1.28%) in the PARP inhibitor and control arms (RR, 0.96; 95% CI, 0.38-2.46; P = .94).

Within the PARP inhibitor group, estimates were derived for patients treated with olaparib or niraparib. The rate of secondary hematologic malignancy for those treated with olaparib was 1.3% compared with 1% in the controls (RR, 1.24; 95% CI, 0.46-3.31; P = .67). The rates were identical among patients assigned to niraparib; 0.47% developed a secondary hematologic malignancy in both the niraparib and control groups (RR, 1.28; 95% CI, 0.30-5.45; P = .74).

Source: Htut T, et al. J Clin Oncol. 2020;38(15_suppl). Abstract 12076.

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