Results of a Multicenter Phase II Study of Atezolizumab and Bevacizumab for Patients With Metastatic Renal Cell Carcinoma With Variant Histology and/or Sarcomatoid Features.

In this multicenter phase II trial, we evaluated atezolizumab combined with bevacizumab in patients with advanced renal cell carcinoma (RCC) with variant histology or any RCC histology with ≥ 20% sarcomatoid differentiation.

Eligible patients may have received previous systemic therapy, excluding prior bevacizumab or checkpoint inhibitors. Patients underwent a baseline biopsy and received atezolizumab 1,200 mg and bevacizumab 15 mg/kg intravenously every 3 weeks. The primary end point was overall response rate (ORR) by RECIST version 1.1. Additional end points were progression-free survival (PFS), toxicity, biomarkers of response as determined by programmed death-ligand 1 (PD-L1) status, and on-therapy quality-of-life (QOL) metrics using the Functional Assessment of Cancer Therapy Kidney Symptom Index-19 and the Brief Fatigue Inventory.

Sixty patients received at least 1 dose of either study agent; the majority (65%) were treatment naïve. The ORR for the overall population was 33% and 50% in patients with clear cell RCC with sarcomatoid differentiation and 26% in patients with variant histology RCC. Median PFS was 8.3 months (95% CI, 5.7 to 10.9 months). PD-L1 status was available for 36 patients; 15 (42%) had ≥ 1% expression on tumor cells. ORR in PD-L1-positive patients was 60% (n = 9) v 19% (n = 4) in PD-L1-negative patients. Eight patients (13%) developed treatment-related grade 3 toxicities. There were no treatment-related grade 4-5 toxicities. QOL was maintained throughout therapy.

In this study, atezolizumab and bevacizumab demonstrated safety and resulted in objective responses in patients with variant histology RCC or RCC with ≥ 20% sarcomatoid differentiation. This regimen warrants additional exploration in patients with rare RCC, particularly those with PD-L1-positive tumors.

Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2019 Nov 13 [Epub ahead of print]

Bradley A McGregor, Rana R McKay, David A Braun, Lillian Werner, Kathryn Gray, Abdallah Flaifel, Sabina Signoretti, Michelle S Hirsch, John A Steinharter, Ziad Bakouny, Ronan Flippot, Xiao X Wei, Atish Choudhury, Kerry Kilbridge, Gordon J Freeman, Eliezer M Van Allen, Lauren C Harshman, David F McDermott, Ulka Vaishampayan, Toni K Choueiri

Dana-Farber Cancer Institute, Boston, MA., Moores Cancer Center, La Jolla, CA., Beth Israel Deaconess Medical Center, Boston, MA., Karmanos Cancer Institute, Detroit, MI.