A phase I trial of autologous RAK cell immunotherapy in metastatic renal cell carcinoma

Treatment of metastatic renal cell carcinoma (mRCC) remains a challenge worldwide. Here, we introduced a phase I trial of autologous RAK cell therapy in patients with mRCC whose cancers progressed after prior systemic therapy. Although RAK cells have been used in clinic for many years, there has been no dose-escalation study to demonstrate its safety and efficacy.

We conducted a phase I trial with a 3 + 3 dose-escalation design to investigate the dose-related safety and efficacy of RAK cells in patients with mRCC whose cancers have failed to response to systemic therapy (ChiCTR1900021334).

Autologous RAK cells, primarily composed of CD8⁺ T and NKT cells, were infused intravenously to patients at a dose of 5 × 10⁹, 1 × 10¹⁰ or 1.5 × 10¹⁰ cells every 28 days per cycle. Our study demonstrated general safety of RAK cells in a total of 12 patients. Four patients (33.3%) showed tumor shrinkage, two of them achieved durable partial responses. Peripheral blood analysis showed a significant increase in absolute counts of CD3⁺ and CD8⁺ T cells after infusion, with a greater fold change observed in naive CD8⁺ T cells (CD8⁺CD45RA⁺). Higher peak values of IL-2 and IFN-γ were observed in responders after RAK infusion.

This study suggests that autologous RAK cell immunotherapy is safe and has clinical activity in previously treated mRCC patients. The improvement in peripheral blood immune profiling after RAK cell infusion highlights its potential as a cancer treatment. Further investigation is necessary to understand its clinical utility.