A phase II study of atezolizumab (atezo) with or without bevacizumab (bev) versus sunitinib (sun) in untreated metastatic renal cell carcinoma (mRCC) patients (pts)

Background: While targeting VEGF improves outcomes for mRCC pts, resistance invariably develops, often within the first year. Here, we describe the efficacy and safety of atezo (anti‐PD‐L1) with bev (anti‐VEGF) and atezo monotherapy vs sun (TKI) in first‐line mRCC. Methods: Treatment‐naïve mRCC pts were enrolled in a hypothesis generating Ph II study (IMmotion150; NCT01984242) and randomized to atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w, atezo alone or sun 50 mg PO QD 4 wk on/2 wk off. Crossover to atezo + bev after disease progression was allowed for pts receiving atezo or sun. PD‐L1 expression was scored on tumor‐infiltrating immune cells (IC, SP142 IHC assay). Coprimary endpoints were PFS (RECIST v1.1 by independent review [IRF]) in ITT pts and pts with PD‐L1 expression on ≥ 1% of IC (PD‐L1+). Results: Baseline characteristics were comparable across arms and between ITT and PD‐L1+ pts. The majority of sun and atezo pts subsequently received atezo + bev. Median survival follow up was 20.7 mo. The PFS HR in ITT pts for atezo + bev vs sun was 1.00 and 1.19 for atezo vs sun. In PD‐L1+ pts, the PFS HR for atezo + bev vs sun was 0.64 and 1.03 for atezo vs sun (table). Tx‐related Gr 3‐4 AEs were seen in 40%, 16% and 57% of pts in the atezo + bev, atezo and sun arms, respectively. AEs leading to death occurred in 3%, 2% and 2% of pts, respectively. Conclusion: Atezo + bev resulted in encouraging antitumor activity in the PD‐L1+ subgroup of first‐line RCC pts. Atezo + bev safety is consistent with the known profile of atezo and bev individually. The clinical benefit of atezo + bev vs sun will be evaluated in the ongoing Ph III study IMmotion151 (NCT02420821). (Table Presented).