Median progression-free survival with veliparib at two different doses in combination with temozolomide nearly doubled compared with placebo; however, the results did not reach statistical significance, a new study published online ahead of print in the journal Annals of Oncology has shown.
For the multicenter, double-blind, phase II trial, researchers enrolled 346 patients with unresectable stage III or IV metastatic melanoma and randomly assigned them 1:1:1 to receive temozolomide plus veliparib 20 mg or 40 mg, or placebo twice daily.
Results showed that median progression-free survival was 3.7 months (95% CI: 3.0, 5.5) with veliparib 20 mg, 3.6 months (95% CI: 1.9, 4.1) with veliparib 40 mg, and 2 (95% CI: 1.9, 3.7) with placebo.
Researchers found that median overall survival was 10.8 (95% CI: 9.0, 13.1), 13.6 (95% CI: 11.4, 15.9), and 12.9 (95% CI: 9.8, 14.3) months, respectively, indicating no statistically significant difference in overall survival between treatment arms.
The study also demonstrated an objective response rate of 10.3% with veliparib 20 mg, 8.7% with veliparib 40 mg, and 7.0% with placebo.
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Exploratory analyses demonstrated an improved progression-free survival among patients with low ERCC1 expression when they received veliparib.
In regard to safety, the frequencies of leukopenia, neutropenia, and thrombocytopenia were significantly higher in the veliparib treatment arms.
Veliparib is a potent, poly ADP-ribose polymerase-1 and -2 inhibitor that has been shown to increase the efficacy of temozolomide in preclinical models.