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Combination treatment with avelumab and regorafenib has shown activity in patients with relapsed/refractory gastrointestinal stromal tumors (GIST), according to research presented at the ESMO Congress 2023.
A subset of patients derived a long-term benefit with the combination, according to study presenter Sophie Cousin, MD, of the Institut Bergonié in Bordeaux, France.
These results were seen in the phase 2 Regomune study (ClinicalTrials.gov identifier: NCT03475953). The trial enrolled 50 patients with unresectable, metastatic GIST. Their median age at baseline was 64 (range, 26-82) years, and 48% of patients were men.
The most common locations of the primary tumor were the stomach (46%) or small intestine (42%). An exon 11 KIT mutation was present in 58% of patients. The median number of prior therapies received was 2 (range, 1-4), and all patients had previously received imatinib.
The patients were treated with regorafenib at 160 mg daily for 3 out of 4 weeks and avelumab at 10 mg/kg every 2 weeks. The median follow-up was 31.2 months.
The 6-month progression-free survival (PFS) rate, the study’s primary endpoint, was 37%. The 1-year PFS rate was 29.3%. The median PFS was 5.5 months.
Patients with a gastric primary tumor were more likely to be progression-free at 6 months (56.7%) than patients with a tumor in the small intestine (16.7%; P =.01). There was no significant difference in PFS according to exon 11 KIT mutation status.
The 6-month overall survival (OS) rate was 95.6%, and the 1-year OS rate was 72.7%. The median OS was 17.7 months.
There were no complete responses, but 6.5% of patients had a partial response, 2.2% had an unconfirmed partial response, and 67.4% had stable disease. The median duration of response was 12.9 months.
All patients experienced at least 1 adverse event (AE). The rate of AEs that were possibly treatment-related was 98%. The rate of grade 3 or higher AEs that were potentially treatment-related was 70%.
The most common grade 3 or higher treatment-related AEs were palmar plantar erythrodysesthesia syndrome (n=9), hypertension (n=9), maculopapular rash (n=6), and diarrhea (n=6). Treatment-related AEs led to discontinuation in 18% of patients.
Disclosures: This study was supported by Bayer and Merck Serono SAS. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Reference
Cousin S, Bellera C, Guegan J-P, et al. Regomune: A phase II study of regorafenib + avelumab in solid tumors – Results of the advanced or metastatic gastrointestinal stromal tumors (mGIST) cohort. Presented at ESMO Congress 2023. Oct. 20-24, 2023. Madrid, Spain. Abstract 1920MO.
This article originally appeared on Cancer Therapy Advisor
