BBOT reports 75% ORR for BBO-8520 plus pembrolizumab in 2L+ NSCLC
BridgeBio Oncology Therapeutics (Nasdaq: BBOT) has published updated clinical data from its ONKORAS-101 Phase 1 study, reporting that BBO-8520 combined with pembrolizumab achieved a 75% objective response rate (ORR) at the 500 mg once-daily dose level in patients with second-line-or-later (2L+) NSCLC who had previously received a KRAS G12C inhibitor. Across all dose levels in that cohort of 17 patients, the ORR was 53%. The data cutoff was 1 June 2026.
As a monotherapy in KRAS G12C inhibitor-naïve 2L+ NSCLC patients, BBO-8520 continued to perform strongly, with an ORR of 63% across 41 patients, a disease control rate of 100%, and no grade 3 liver enzyme elevations. Among 28 patients eligible for a six-month follow-up, 75% remained on treatment beyond that point, a durability signal the company views as meaningful.
The science and the strategy
BBO-8520 is designed as a dual ON/OFF state KRAS G12C inhibitor, a mechanism intended to achieve deeper pathway suppression than first-generation OFF-state-only agents such as sotorasib and adagrasib. By targeting the active (ON) conformation as well as the inactive (OFF) state, BBOT argues the compound can achieve potent inhibition at lower free-drug exposures, which in turn may allow tolerable combination with a checkpoint inhibitor such as pembrolizumab. Safety data reported so far support that hypothesis: adverse events in the combination arm were predominantly gastrointestinal, with a profile the company describes as manageable.
The strategic rationale for the pembrolizumab combination is rooted in the evolving treatment landscape. BBOT estimates that approximately 21,000 patients in the United States will be diagnosed this year with NSCLC harbouring a KRAS G12C mutation. As G12C inhibitors begin to move into first-line treatment, an increasing number of patients will subsequently progress on those agents and face a setting where no approved targeted therapy currently exists. BBOT is positioning the combination programme squarely at that emerging 2L+ population.
Pipeline and financial runway
Beyond BBO-8520, the company is enrolling combination cohorts for two further KRAS-targeting compounds, BBO-11818 and BBO-10203, in patients with KRAS-mutant colorectal cancer and pancreatic ductal adenocarcinoma. Both indications carry significant unmet need: KRAS mutations drive the majority of PDAC cases and are common in CRC, yet no approved KRAS-targeted therapy exists for either tumour type. Monotherapy data updates for both programmes are expected in the fourth quarter of 2026, with combination readouts and an expanded BBO-8520 plus pembrolizumab dataset anticipated in mid-2027.
Chief executive Pedro Beltran said the portfolio had now generated "encouraging clinical data" across all three programmes, enabling the company to concentrate capital on the opportunities it views as most likely to succeed.
BBOT reported cash, equivalents and marketable securities of $344.1 million as of 30 June 2026, which management projects will fund operations into 2028. That runway provides meaningful insulation ahead of the mid-2027 data wave.
Competitive landscape
The KRAS G12C field has become one of the more crowded corners of oncology drug development. Amgen's sotorasib and Mirati's adagrasib are both approved in NSCLC, while Roche, Pfizer and several clinical-stage biotechs are pursuing next-generation or combination strategies. The primary competitive question for BBO-8520 is whether the dual ON/OFF mechanism translates into a clinically meaningful advantage over approved agents or rival combination programmes at comparable development stages. The Phase 1 ORR figures are encouraging in that context, though the dataset remains small and no head-to-head comparisons are available. Full dose-escalation data and, eventually, a randomised study will be required before the combination's place in the treatment algorithm can be established.