Phase II Trial of Cabozantinib in Recurrent/Metastatic Endometrial Cancer: A Study of the Princess Margaret, Chicago, and California Consortia (NCI9322/PHL86)

The relevance of the MET/hepatocyte growth factor pathway in endometrial cancer tumor biology supports the clinical evaluation of cabozantinib in this disease. PHL86/NCI#9322 (NCT01935934) is a single arm study that evaluated cabozantinib (60 mg once daily) in women with endometrial cancer with progression after chemotherapy. Coprimary endpoints were response rate and 12-week progression-free-survival (PFS). Patients with uncommon histology endometrial cancer (eg, carcinosarcoma and clear cell) were enrolled in a parallel exploratory cohort. A total of 102 patients were accrued. Among 36 endometrioid histology patients, response rate was 14%, 12-week PFS rate was 67%, and median PFS was 4.8 months. In serous cohort of 34 patients, response rate was 12%, 12-week PFS was 56%, and median PFS was 4.0 months. In a separate cohort of 32 patients with uncommon histology endometrial cancer (including carcinosarcoma), response rate was 6% and 12-week PFS was 47%. Six patients were on treatment for >12 months, including two for >30 months. Common cabozantinib-related toxicities (>30% patients) included hypertension, fatigue, diarrhea, nausea, and hand-foot syndrome. Gastrointestinal fistula/perforation occurred in four of 70 (6%) patients with serous/endometrioid cancer and five of 32 (16%) patients in exploratory cohort. We observed increased frequency of responses with somatic mutation [four partial responses (PRs) in 10 patients, median PFS 7.6 months] and concurrent and mutations (three PRs in 12 patients, median PFS 5.9 months). Cabozantinib has activity in serous and endometrioid histology endometrial cancer. These results support further evaluation in genomically characterized patient cohorts.