Interim results from phase 2 of the SUMMIT basket trial has found that neratinib is safe and tolerable in patients with advanced biliary tract cancers. According to Puma Biotechnology, the results also demonstrated activity similar to current standards of care.

The phase 2 SUMMIT basket trial is an open-label, multicenter, multinational study that included a cohort evaluating daily neratinib administered to patients with human epidermal growth factor 2 (HER2) mutation-positive advanced biliary cancer. Participants received 240 mg of neratinib daily as a single agent. The interim results were presented at the 2021 American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium.

In the cohort of 25 patients, 11 patients had cholangiocarcinoma, 10 patients had cancer of the gallbladder, and 4 patients had cancer of the ampulla of Vater. Of the 25 participants, 24 had received prior systemic chemotherapy with a median of 2 prior lines of therapy (ranging from 0 to 7) before entering the trial.

According to Puma Biotechnology, the efficacy results demonstrated that there were 4 patients with confirmed partial response, 3 of whom had gallbladder cancer and 1 who had cholangiocarcinoma. An additional 3 patients had stable disease lasting 16 weeks or longer. One patient with cholangiocarcinoma remained on treatment for 56 weeks before progression. These findings resulted in an objective response rate of 16%, and a clinical benefit rate of 28%. The durations of response were 3 months, 3.7 months, and 4.7 months, and 1 patient with gallbladder cancer has remained on treatment for more than 80 weeks.

The safety profile for patients with biliary tract tumors is similar to that previously reported for patients treated with neratinib monotherapy and mandatory loperamide prophylaxis in the first 2 months. According to Puma Biotechnology, treatment was manageable, with 56% of patients experiencing some diarrhea, including 24% with grade 3 diarrhea. There were no episodes of grade 4 diarrhea and no treatment discontinuations due to diarrhea. Four patients required dose reduction of neratinib, and 1 patient was hospitalized due to diarrhea.

“We have shown neratinib to be safe and tolerable in these patients with advanced biliary tract tumors and demonstrated activity comparable to current standards of care with similar progression-free survival and overall survival in these heavily pretreated patients,” said presenter James J. Harding, MD, regional director of early drug development at Memorial Sloan Kettering Cancer Center, in a prepared statement.

Puma Biotechnology Presents Interim Results from the Biliary Tract Cancers Cohort of the Phase II SUMMIT “Basket” Trial of Neratinib at ASCO GI [news release]. Los Angeles, CA; January 15, 2021: Business Wire. Accessed February 10, 2021.