Select patients with advanced pancreatic cancer may have another effective treatment option for maintenance therapy. New data show that rucaparib is effective in stopping tumor growth or substantially shrinking tumors in the majority of patients with select biomarkers enrolled in a phase II trial by researchers at the Abramson Cancer Center at the University of Pennsylvania in Philadelphia.1 The open-label, single-arm, single-stage, phase II study was conducted to test the hypothesis that rucaparib, a poly(adenosine diphosphate ribose) polymerase inhibitor (PARPi), would confer at least 60% progression-free survival at 6 months as maintenance therapy in patients with platinum-sensitive advanced pancreatic cancer with select biomarkers. The study included 46 patients with locally advanced or metastatic pancreatic cancer with confirmed or likely pathogenic germline or somatic pathogenic variants in BRCA1, BRCA2, or PALB2 genes. Patients were aged at least 18 years and had received prior treatment with platinum-based chemotherapy; 34 patients received at least 16 weeks or more, whereas 8 patients received less than 16 weeks. All patients were treated with rucaparib at a dose of 600 mg delivered orally twice a day during every day of a 28-day cycle until disease progression or unacceptable toxicity. For the 42 patients available for evaluation, the progression-free survival rate at 6 months was 59.5%, and the median progression-free survival was 13.1 months. When disease control was examined, 41.7% of the patients, including 3 of 6 patients with the variant PALB2 and 1 of 2 patients with a somatic BRCA2 mutation, experienced either a complete response or a partial response. Kim A. Reiss, MD, assistant professor at the Abramson Cancer Center and lead author of the study, says that these findings expand on prior results from the phase III POLO study showing the efficacy of maintenance olaparib, the first poly(adenosine diphosphate ribose) polymerase 1 (PARP1) agent to be used as maintenance therapy for advanced pancreatic cancer, in select patients with germline BRCA mutations and platinum-sensitive metastatic pancreatic cancer.2 “Our study showed efficacy in patients with additional variants,” she says. “The role of maintenance PARP inhibition may possibly be expanded to patients with germline PALB2 mutations and those with somatic BRCA mutations.” Dr. Reiss also notes the efficacy of rucaparib for patients with locally advanced disease and patients who did not receive a full 4 months of prior platinum therapy. “Although platinum sensitivity is key for PARPi efficacy, a full 4 months of treatment may not be required prior to switching to maintenance therapy,” she says. This finding is important because of toxicities of platinum-based chemotherapy that typically emerge before the completion of 16 weeks of therapy.
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