Gemcitabine plus platinum-based chemotherapy in combination with bevacizumab for kidney metastatic collecting duct and medullary carcinomas: Results of a prospective phase II trial (BEVABEL-GETUG/AFU24)

Background: Renal medullary carcinoma (RMC) and collecting duct carcinoma (CDC) are rare entities with a poor outcome. First-line metastatic treatment is based on gemcitabine + platinum chemotherapy (GC) regimen but retrospective data suggest enhanced anti-tumour activity with the addition of bevacizumab. Therefore, we performed a prospective assessment of the safety and efficacy of GC + bevacizumab in metastatic RMC/CDC. Methods: We conducted a phase 2 open-label trial in 18 centres in France in patients with metastatic RMC/CDC and no prior systemic treatment. Patients received bevacizumab plus GC up to 6 cycles followed, for non-progressive disease, by maintenance therapy with bevacizumab until progression or unacceptable toxicity. The co-primary end-points were objective response rates (ORRs) and progression-free survival (PFS) at 6 months (ORR-6; PFS-6). PFS, overall survival (OS) and safety were secondary end-points. At interim analysis, the trial was closed due to toxicity and lack of efficacy. Results: From 2015 to 2019, 34 of the 41 planned patients have been enroled. After a median follow-up of 25 months, ORR-6 and PFS-6 were 29.4% and 47.1%, respectively. Median OS was 11.1 months (95% confidence interval [CI]: 7.6–24.2). Seven patients (20.6%) discontinued bevacizumab because of toxicities (hypertension, proteinuria, colonic perforation). Grade 3–4 toxicities were reported in 82% patients, the most common being haematologic toxicities and hypertension. Two patients experienced grade 5 toxicity (subdural haematoma related to bevacizumab and encephalopathy of unknown origin). Conclusion: Our study showed no benefit for bevacizumab added to chemotherapy in metastatic RMC and CDC with higher than expected toxicity. Consequently, GC regimen remains a therapeutic option for RMC/CDC patients.