Durability of complete response (CR) with atezolizumab (atezo) in locally advanced/metastatic urothelial carcinoma (mUC).

Yohann Loriot Institut de Cancérologie Gustave Roussy, Villejuif, France info_outline Yohann Loriot, Arjun Vasant Balar, Robert Dreicer, Jean H. Hoffman-Censits, Jose Luis Perez-Gracia, Daniel Peter Petrylak, Michiel Simon Van Der Heijden, Xiaodong Shen, Qian (Cindy) Zhu, Beiying Ding, Constanze Kaiser, Jonathan E. Rosenberg

Authors Yohann Loriot Institut de Cancérologie Gustave Roussy, Villejuif, France info_outline Yohann Loriot, Arjun Vasant Balar, Robert Dreicer, Jean H. Hoffman-Censits, Jose Luis Perez-Gracia, Daniel Peter Petrylak, Michiel Simon Van Der Heijden, Xiaodong Shen, Qian (Cindy) Zhu, Beiying Ding, Constanze Kaiser, Jonathan E. Rosenberg Organizations Institut de Cancérologie Gustave Roussy, Villejuif, France, Perlmutter Cancer Center at NYU Langone Health, New York, NY, University of Virginia, Charlottesville, VA, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD, Department of Medical Oncology, Clinica Universidad de Navarra, Pamplona, Spain, Yale School of Medicine, New Haven, CT, Netherlands Cancer Institute, Amsterdam, Netherlands, Oncology, Genentech, Inc., South San Francisco, CA, Genentech, Inc., San Francisco, CA, Genentech, Inc., South San Francisco, CA, Genentech, South San Francisco, CA, Memorial Sloan Kettering Cancer Center, New York, NY Abstract Disclosures Research Funding Pharmaceutical/Biotech Company Background: Atezo (anti–PD-L1) has been shown to elicit CRs in a number of mUC patients (pts) in clinical trials. We sought to describe the kinetics, durability and outcomes associated with these CRs in Ph I (PCD) and II (IMvigor210) atezo studies, each with long-term follow-up. Methods: In PCD (pre-treated mUC) and IMvigor210 (Cohort 1, cisplatin-ineligible untreated mUC; Cohort 2, platinum-treated mUC), pts received atezo per protocol (Petrylak JAMA Oncol 2018; Balar Lancet 2017; Rosenberg Lancet 2016). This post hoc analysis descriptively assessed pt disposition, time to and duration of RECIST 1.1 response and overall survival in pts with CR. Results: CR rates were 13%, 8% and 7% in PCD, IMvigor210 Cohort 1 and Cohort 2, respectively. First response was PR in most pts with CR. Median CR duration was > 3 y in PCD, not estimable (NE) in IMvigor210 Cohort 1 and > 2 y in Cohort 2 (Table). At data cutoff, all but 2, 0 and 1 pts were alive, respectively; across studies, ≥ 40% of pts with CR were on treatment. CR pts had a first response (PR/CR) by a median of 3.5 cycles. Further pt characteristics and survival outcomes will be reported. Conclusions: Across Ph I/II atezo mUC studies, CRs appeared durable (median duration > 2 y) despite small pt numbers. Most pts with CR were alive, with responses ongoing after long-term follow-up (median follow-up > 30 mo). Clinical trial information: NCT01375842, NCT02951767, NCT02108652 PCD (n = 12) a IMvigor210 Cohort 1 (n = 10) b IMvigor210 Cohort 2 (n = 22) c Median atezo duration (range), mo 33.6 (10.4-44.4) 21.5 (6.2-35.9) 32.6 (8.8-35.6) Median time to first response (range), mo d 1.4 (1.2-8.3) 2.2 (2.0-10.3) 2.0 (1.9-8.2) Median doses to first response (range), n 2.0 (2-12) 3.5 (3-15) 3.0 (3-12) Median time to CR (range), mo 8.1 (1.2-28.3) 6.2 (2.1-13.8) 4.2 (1.9-13.2) Median CR duration (95% CI), mo 37.5 (33.3, 37.5) NE 28.4 (18.6, NE) Pts with ongoing CR, n (%) e 8 (67) 8 (80) 12 (55) Pts with CR as first response, n (%) 2 (17) 3 (30) 8 (36) Treatment discontinuations due to PD, n (%) 2 (17) 0 3 (14) Treatment discontinuations due to non-PD, n (%) f 2 (17) 6 (60) 3 (14) PD, progressive disease. Data cutoff (median follow-up, mo): a Dec 31, 2016 (40.8); b Jul 12, 2017 (31.7); c Jul 12, 2017 (33.1). d First response of CR or PR. e No PD/death. f Excluded 1 PCD pt who completed only 16 cycles per an earlier protocol.