Abstract
Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare kidney tumor which is usually characterized by indolent disease physiology. While several high-grade and sarcomatoid MTSCC tumors have been reported, the clinical experience with contemporary immune checkpoint blockade (ICB) combination therapies extrapolated from treatment paradigms of conventional renal cell carcinoma (RCC) remains limited. Here, we report two patients with metastatic MTSCC treated with first-line ipilimumab plus nivolumab therapy who both achieved great clinical benefit. We subsequently performed immune deconvolution analysis on previously identified MTSCC-like kidney tumors from The Cancer Genome Atlas (TCGA) and discovered significantly higher PD-L1 transcriptomic expression compared to similar papillary RCC tumors, providing additional biomarker data supporting the observed ICB response. These data implicate ICB therapy as an effective treatment for patients with metastatic MTSCC.