Multi-institutional Analysis of Immune-Oncology Combination Therapy for Metastatic MiT Family Translocation Renal Cell Carcinoma

Metastatic translocation renal cell carcinomas (mtRCCs) are rare and aggressive tumors with limited treatment options. Recent studies demonstrated promising activity of immune-oncology (IO) combinations in mtRCC. However, the effectiveness of dual IO combinations versus IO plus VEGF-TKI combinations remains unclear. We conducted a retrospective analysis of IO combinations in mtRCC patients at 4 institutions. Eligible patients had confirmed mtRCC by genitourinary pathologist and received IO combination therapy (IO+IO or IO+VEGF-TKI). Clinical data and treatment outcomes were recorded from the start of systemic therapy. Objective response rate (ORR) was retrospectively evaluated, and time to treatment failure (TTF), and overall survival (OS) were compared for IO+IO and IO+VEGF-TKI groups. We identified 22 mtRCC patients who received IO combinations, all confirmed to have TFE3 rearrangement by FISH. Most patients were female (68%) with a median age of 41 years (16-79). Treatment breakdown included: IO+IO (n=8, 36%) and IO+VEGF-TKI (n=14, 64%). In the evaluable patients for the efficacy analysis, ORR was 14% (1/7) for the IO+IO group and 54% (6/11) for the IO+VEGF-TKI group. With a median follow-up of 32.4 months, the median TTF was 1.2 months and 6.2 months in the IO+IO and IO+VEGF-TKI groups, respectively (P=0.12). There was no statistically significant difference in median OS between both groups, 36.7 months in the IO+IO group and 15.6 months in IO+VEGF-TKI (P=0.9). Our findings demonstrate that IO+VEGF-TKI resulted in higher ORR and TTF point estimates without statistically detectable differences, compared with IO+IO therapy. Larger studies are needed to validate these findings and optimize treatment selection.