Salvage Immune Checkpoint Inhibitor (Io) Plus Tyrosine Kinase Inhibitor (Tki) Combination Therapy For Metastatic Renal Cell Carcinoma (Mrcc)

e16567 Background: ICI/TKI combinations are a new standard of care for the initial treatment (tx) of mRCC. Efficacy and toxicity of such combination regimens beyond the first-line (1L) setting remain unknown. Methods: We retrospectively reviewed charts for adult patients (pts) receiving an ICI/TKI combination in any line of tx for mRCC of any histology at one of two academic centers as of May 1, 2020. ICIs included pembrolizumab (Pm), nivolumab (Ni), ipilimumab (Ip), or avelumab (Av); TKIs included sunitinib (Su), axitinib (Ax), pazopanib (Pz), lenvatinib (Ln), or cabozantinib (Ca). Clinical data including pt demographics, histology, International mRCC Database Consortium (IMDC) risk group, tx history, and ICI/TKI tx and toxicity details were recorded. Outcomes included objective response rate (ORR), median progression-free survival (mPFS), and safety, analyzed via descriptive statistics and the Kaplan-Meier method. Results: Of 85 pts, 69 (81%) were male and 67 (79%) had clear cell histology. IMDC risk was favorable (24%), intermediate (54%), poor (20%), and unknown (2%). 39% had ICI/TKI tx in the 1L setting. ICI/TKI regimens included Pm/Ax (33%), Ni/Ca (25%), Ni/Ax (20%), Av/Ax (11%), Ni/Ip/Ca (8%), Ni/Su (2%), and Ni/Ln (1%). ORR and mPFS stratified by line of tx and prior tx are shown in the table. Of 52 pts who received ICI/TKI tx as salvage (after 1L), 52% had a grade 3 or higher (≥G3) adverse event (AE), of which the most common were anorexia (13.5%), diarrhea and hypertension (11.5% each), and fatigue (9.6%). 65% of pts on salvage ICI/TKI tx stopped tx for progression/death, while 16% stopped tx for ≥G3 AE. ≥G3 AE rates by line of tx were 62.5% (2L), 50% (3L), and 45% (≥4L). Conclusions: ICI/TKI combination therapy is effective and safe beyond the 1L setting. Prior tx history appears to impact efficacy but has less of an effect on safety/tolerability. These observations will need to be confirmed in prospective studies.[Table: see text]