Salvage ipilimumab associated with a significant response in sarcomatoid renal cell carcinoma

BACKGROUND: Metastatic sarcomatoid renal cell carcinoma (sRCC) is an aggressive variant of RCC with generally poor prognosis. Treatment with vascular endothelial growth factor inhibitors or chemotherapy generates only short-lived responses. Recent research has suggested a role for combination checkpoint inhibition as first line treatment for metastatic sRCC. This therapy consists of induction with cytotoxic T-lymphocyte-associated protein 4 inhibitor, ipilimumab, administered with programmed cell death protein 1 (PD-1) inhibitor, nivolumab. After completion of four cycles of combination therapy, single-agent maintenance nivolumab is recommended until progression. Patients who progress on maintenance nivolumab are switched to alternate therapy. Herein, we present a case of a patient with RCC who progressed on maintenance nivolumab who, on retreatment with ipilimumab, demonstrated a significant response In addition, we summarize important findings to support the role of salvage ipilimumab in patients with sRCC. CASE PRESENTATION: A 46-year-old man presented with flank pain and hematuria, the work up of which noted a left kidney mass for which he underwent nephrectomy and was diagnosed with localized sRCC with 60% sarcomatoid differentiation. Within 3 months of nephrectomy, he presented with recurrent flank pain and was diagnosed with recurrence of disease. He was treated with ipilimumab 1 mg/kg and nivolumab 3 mg/kg for four doses and demonstrated a partial response. He was then transitioned to single agent nivolumab maintenance. After 3 months on maintenance therapy, he was noted to have progression of disease. Given prior response to immune check point combination, it was decided to rechallenge the patient with 1 mg/kg ipilimumab. After two doses of ipilimumab and nivolumab combination therapy, the patient was noted to have a partial response. He maintained a response for an additional 9 months and treatment was eventually discontinued due to grade 3 toxicity and progression. CONCLUSIONS: This case report demonstrates the utility of retreatment with ipilimumab as a salvage option for patients progressing on maintenance PD-1 inhibitors in metastatic RCC. Further studies are needed to identify predictors of response and toxicity to this approach, as well as the optimal scheduling of ipilimumab with maintenance nivolumab.