Nktr-214+Nivolumab In First-Line Advanced/Metastatic Urothelial Carcinoma (Muc): Updated Results From Pivot-02.

388 Background: Single-agent checkpoint inhibitors have changed the mUC treatment landscape; however, unmet need remains in first-line (1L) cisplatin ineligible mUC, particularly for PD-L1 negative (–) patients (pts). NKTR-214 is a CD122-biased agonist designed to provide sustained signaling through the IL-2 βγ receptor. PIVOT-02 is an ongoing study of NKTR-214 + nivolumab (nivo) in pts with advanced cancers, including mUC. Methods: Pts with mUC who were 1L cisplatin ineligible or refused standard of care (SOC) received NKTR-214 IV 0.006 mg/kg + nivo IV 360 mg q3w. Responses were assessed every 8 wks. Matched blood and tumor biopsies were evaluated for biomarkers including PD-L1 expression (assessed by Dako 28-8 PharmaDx IHC; PD-L1+ defined as ≥ 1% tumor cell staining). Results: As of 11 Oct. 2018, 34 pts received ≥ 1 dose of treatment (cisplatin ineligible [n=22]; refused SOC [n=12]). Median age was 70. Of 34 pts, 23 were efficacy evaluable (defined per protocol as having ≥ 1 post-treatment scan), 7 were pending a first scan, 1 pt was excluded for non-eligibility (no target lesion), and 3 discontinued prior to first scan. Thresholds for efficacy were exceeded in all 1L mUC cohorts under a pre-specified Fleming ORR analysis. In the efficacy evaluable population, overall ORR was 48% (11/23; 95% CI 27–69%) with a 17% CR rate (4/23) and 70% (16/23) DCR. The ORR was 50% in PD-L1– pts (5/10; 95% CI 19–81%) and 56% in PD-L1+ pts (5/9; 95% CI 21–86%). PD-L1 status was unknown in 4 efficacy-evaluable pts. The most common treatment-related AEs (TRAE, >30%) were fatigue (59%), pyrexia (38%), chills (32%), and flu-like symptoms (32%). Grade ≥ 3 TRAEs occurred in 18% of pts and 8.8% discontinued due to TRAEs. No G4/G5 TRAEs occurred. 22 pts had available baseline PD-L1 results (PD-L1+ [n=11]; PD-L1– [n=11]). 10 of the 11 PD-L1– baseline samples had matched wk 3 biopsies. Of these, 6/10 (60%) converted to PD-L1+ at wk 3. Updated results will be presented. Conclusions: NKTR-214 + nivo showed encouraging clinical activity, including CRs, and an acceptable preliminary safety profile in pts with mUC. Efficacy appears independent of PD-L1 status with a similar ORR in PD-L1– and + tumors. These data support further evaluation of the combination. Clinical trial information: NCT02983045.