SAN FRANCISCO – The combination of cisplatin and gemcitabine is highly efficacious as first-line therapy for advanced pancreatic cancer in patients with a germline BRCA1/2 or PALB2 mutation, with no additional benefit seen from concurrent veliparib, a phase 2 randomized controlled trial finds.
MDedge News/Susan London
Dr. Eileen Mary O'Reilly
Up to 9% of pancreatic ductal adenocarcinomas occur in individuals with one of these germline mutations, which render cells more sensitive to platinum agents and PARP inhibitors because of ineffective DNA repair.
In the trial, nearly two-thirds of patients had a response to cisplatin-gemcitabine alone, according to results reported at the 2020 GI Cancers Symposium and simultaneously published (J Clin Oncol. 2020 Jan 24. doi: 10.1200/JCO.19.02931). Although almost three-quarters had a response when the investigational PARP 1/2 inhibitor veliparib was added, the difference was not statistically significant and toxicity was greater.
“Both arms were very active and substantially exceeded the prespecified thresholds,” said lead investigator Eileen Mary O’Reilly, MD, section head of Hepatopancreaticobilary & Neuroendocrine Cancers at Memorial Sloan Kettering Cancer Center in New York.
“The doublet is our recommendation for moving forward, and we believe these data define a reference regimen for germline BRCA-mutated or PALB2-mutated pancreas cancer,” she stated, noting that the PARP inhibitor olaparib (Lynparza) conferred benefit when used as maintenance therapy in the POLO trial. “I think the strategy that at the current time is best supported by the totality of the data is platinum-based therapy upfront and then sequential use of the PARP inhibitor as a maintenance approach.”
The trial was designed in 2012, before efficacy of the FOLFIRINOX regimen was well established, so an obvious question is which chemotherapy to use, Dr. O’Reilly acknowledged.
“I would say these are the only prospective randomized data we have with platinum-based therapy in germline-mutated pancreas cancer. So it comes with a high level of evidence,” she maintained. “Nonetheless, I think FOLFIRINOX is also an option. The options are good, and it probably will depend on the patient in front of you because there certainly are some lack of toxicity advantages, for the most part, to cisplatin and gemcitabine. This was a well-tolerated regimen.”
Implications for practice
“I wouldn’t say this is a negative study. It’s negative with respect to the veliparib question, but otherwise, it’s a very exciting study,” Richard L. Schilsky, MD, chief medical officer and executive vice president of ASCO, said in an interview. “Seeing response rates of 60% and 70% in patients with metastatic pancreatic cancer is kind of unprecedented, and that’s quite remarkable.”
The reason for the lack of additional benefit from veliparib is unclear, he said. But it may be related to the specific PARP inhibitor or to the smaller sample size or very high response rate seen with chemotherapy alone, which possibly precluded detection of a significant difference.
When choosing between chemotherapy regimens, evidence favors the doublet, according to Dr. Schilsky. “FOLFIRINOX doesn’t have a 70% response rate; it may be 35%. If it was my family member, I would say, get gemcitabine-platinum if you have a BRCA mutation.”
“I think the real take-home message, quite honestly, for most oncologists is that patients with pancreatic cancer should be tested for germline BRCA mutations,” he recommended. “It can not only help inform the therapy choice, but of course, some of these cancers are going to run in families because these are germline mutations and they are going to reveal families that have a high risk of not only pancreatic cancer, but breast, ovarian, and all the other BRCA-associated cancers.”