Novel pembrolizumab-based treatments as first-line therapy in advanced clear-cell renal cell carcinoma: substudy 03A of the open-label, umbrella platform, phase I/II KEYMAKER-U03 trial.

BACKGROUND

First-line triplet therapy may expand clinical benefit for advanced clear-cell renal cell carcinoma (ccRCC). The phase Ib/II KEYMAKER-U03 substudy 03A (NCT04626479) investigated novel pembrolizumab (pembro)-based regimens in this setting.

PATIENTS AND

METHODS

Participants with advanced ccRCC and no prior systemic therapy were randomized 2 : 1 to quavonlimab (qmab)/pembro plus lenvatinib (lenva), favezelimab (fave)/pembro plus lenva, pembro plus lenva plus belzutifan (bel), and vibostolimab (vibo)/pembro plus bel or a concurrent reference treatment (pembro plus lenva). A safety lead-in of ∼10 participants occurred for all investigative treatments before randomization. Primary endpoints were objective response rate (ORR) per RECIST v1.1 by blinded independent central review in all randomized participants (excluding safety lead-in), and safety in all treated participants. Secondary endpoints included progression-free survival (PFS) and overall survival (OS).

RESULTS

As of 31 March 2025, 393 participants were enrolled. Median follow-up for randomized participants across the five cohorts ranged between 16 and 39 months. The ORR was 80.6% [95% confidence interval (CI) 68.6% to 89.6%] with pembro plus lenva, 71.3% (95% CI 60.0% to 80.8%) with qmab/pembro plus lenva, 62.7% (95% CI 48.1% to 75.9%) with fave/pembro plus lenva, 77.5% (95% CI 66.8% to 86.1%) with pembro plus lenva plus bel, and 42.5% (95% CI 31.5% to 54.1%) with vibo/pembro plus bel. Median PFS was 26.3 months (95% CI 15.3-39.8 months) with pembro plus lenva, 18.0 months (95% CI 11.6-34.3 months) with qmab/pembro plus lenva, 26.0 months (95% CI 8.2-31.8 months) with fave/pembro plus lenva, 31.8 months [95% CI 26.3 months-not reached (NR)] with pembro plus lenva plus bel, and 15.2 months (95% CI 12.4 months-NR) with vibo/pembro plus bel. Median OS was not reached in any arm. Grade ≥3 treatment-related adverse events occurred in 71.0% (44/62) of participants treated with pembro plus lenva, 73.3% (66/90) with qmab/pembro plus lenva, 86.9% (53/61) with fave/pembro plus lenva, 70.0% (63/90) with pembro plus lenva plus bel, and 68.9% (62/90) with vibo/pembro plus bel.

CONCLUSIONS

Observed efficacy and safety of pembro plus lenva were confirmatory of prior observations for this combination. ORR was similar to reference for pembro plus lenva plus bel and qmab/pembro plus lenva, but not the other investigative arms. Further investigation of pembro plus lenva plus bel and qmab/pembro plus lenva versus pembro plus lenva is ongoing in the phase III LITESPARK-012 study.