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Preliminary results of the TACITO trial indicated that fecal microbiota transplantation (FMT) significantly improved progression-free survival in patients receiving pembrolizumab and axitinib for metastatic renal cell carcinoma (RCC). FMT was well tolerated and could enhance the efficacy of immune checkpoint inhibitor (ICI) and VEGFR-TKI combination therapies.

Chiara Ciccarese, MD, from Fondazione Policlinico Universitario Agostino Gemelli IRCCS, in Italy, presented the preliminary findings of the phase 2 TACITO trial (NCT04758507), which explored the use of FMT versus placebo in patients receiving pembrolizumab and axitinib for metastatic RCC¹. The study focused on the role of gut microbiota in influencing the efficacy of ICIs, particularly in RCC, where it has been shown that the composition of the intestinal microbiota may affect response to ICIs².

The TACITO trial aimed to determine whether FMT from a patient who had responded to treatment could enhance the anti-tumor activity of pembrolizumab and axitinib in patients with treatment-naïve metastatic RCC. Participants (n=50) were randomly assigned to receive either FMT or placebo at three intervals alongside standard treatment with pembrolizumab and axitinib. The primary endpoint of the study was the proportion of participants free from progression after 1 year, and the results were promising: the 1-year progression-free survival (PFS) rate was significantly higher in the FMT group compared with the placebo group (66.7% vs 35.0%; P=0.036). The median PFS was also extended, with participants who received FMT achieving a median of 14.2 months, compared with 9.2 months in the placebo group. The overall response rate (ORR) was 52% in the FMT group, compared with 28% in the placebo group, although no complete responders were identified in either cohort. The overall survival (OS) was not reached in the intervention arm, whereas it was 25.3 months in the placebo group.

Despite some challenges with administering FMT, Dr. Ciccarese highlighted that the procedure was well tolerated, with no severe AEs reported. “The preliminary results suggest that FMT could play a significant role in enhancing the efficacy of ICI and VEGFR-TKI therapies in metastatic RCC,” she explained. However, she stressed that longer follow-up is necessary to fully assess the impact of FMT on OS and median PFS.

Further microbiome analysis is ongoing to better understand the changes in gut microbiota before and after FMT. Dr. Ciccarese concluded that while these early findings are encouraging, they warrant further investigation in larger, randomized trials to explore the potential of FMT as a complementary treatment in metastatic RCC.

Medical writing support was provided by Dr. Rachel Giles.

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