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BridgeBio Oncology Therapeutics reported data from its phase 1 Onkoras-101 trial suggesting its KRAS G12C inhibitor BBO-8520 may be more effective than existing drugs in the class.

The company said BBO-8520 achieved a 65% overall response rate (ORR) in second-line KRAS G12C-mutant non-small cell lung cancer (NSCLC) among 17 patients; that figure includes one unconfirmed response. Excluding the unconfirmed response yields a confirmed ORR of 58%. By comparison, Amgen’s Lumakras produced a 36% ORR and Bristol Myers Squibb’s Krazati a 43% ORR in trials supporting accelerated approval. Revolution Medicines’ elironrasib, which also targets the on state of KRAS G12C, has reported a 56% ORR in a similar setting.

BBO-8520 targets both the “on” and “off” states of KRAS G12C, while approved drugs only target the off state. BridgeBio says this dual-state activity could increase potency and lower the drug levels needed for efficacy.

BridgeBio also presented early combination data for BBO-8520 plus the PD-1 inhibitor pembrolizumab (Keytruda). Among eight patients — both treatment-naive and previously treated — five had partial responses: three of three in the treatment-naive cohort and two of five in the treatment-experienced cohort (all of whom had prior KRAS G12C inhibitor therapy). Responses were observed across PD-L1 expression levels, including two in patients with 1–2% expression.

Combining KRAS G12C inhibitors with checkpoint inhibitors has been challenging previously, with liver enzyme elevations derailing some efforts. BridgeBio reported one case of grade 3 liver enzyme elevation in the BBO-8520/Keytruda cohort, which the company attributed to concomitant medications; the event resolved and the patient remained on therapy.

Investors reacted positively to the update, sending BridgeBio Oncology Therapeutics’ stock up about 4% on Wednesday. BridgeBio expects another BBO-8520 update in the second half of 2026 and plans a combination program pairing the agent with its PI3Kα:RAS breaker BBO-10203.

BridgeBio Oncology Therapeutics reported early clinical data suggesting its KRAS G12C inhibitor BBO-8520 may outperform existing drugs in the class.

In the phase 1 Onkoras-101 trial, the company announced a 65% overall response rate (ORR) in second-line KRAS G12C-mutant non-small cell lung cancer based on 17 patients. One response was unconfirmed; excluding that case lowers the ORR to 58%. Those figures compare with ORRs of 36% for Amgen’s Lumakras and 43% for Bristol Myers Squibb’s Krazati in trials supporting their accelerated approvals, and are similar to Revolution Medicines’ reported 56% ORR for elironrasib. BridgeBio cautioned the findings are early and based on small numbers and will need confirmation in larger studies.

BBO-8520 is designed to bind both the active (“on”) and inactive (“off”) states of KRAS G12C, while approved agents target only the off state. BridgeBio says this dual-state targeting could increase potency and reduce required drug levels.

BridgeBio also released initial results for BBO-8520 combined with pembrolizumab (Keytruda). Among eight patients—both treatment-naive and treatment-experienced—five achieved partial responses: three of three in the treatment-naive cohort and two of five in the treatment-experienced cohort (all of whom had prior KRAS G12C inhibitor therapy). Responses were observed across PD-L1 expression levels, including two responses in patients with 1–2% PD-L1. One grade 3 liver enzyme elevation was reported; the company attributed it to co-medications, said the event resolved, and the patient remained on therapy.

Investors appeared encouraged by the update, sending BridgeBio Oncology Therapeutics’ stock up about 4% at Wednesday’s close.

BridgeBio plans another data update in the second half of 2026 and intends to test BBO-8520 in combination with its PI3Kα:RAS breaker BBO-10203.

BridgeBio Oncology Therapeutics (BBOT) reported phase 1 data suggesting its KRAS G12C inhibitor BBO-8520 may outperform existing agents in second-line non–small cell lung cancer (NSCLC). In the Onkoras-101 trial the company reported a 65% overall response rate (ORR) among 17 patients; excluding one unconfirmed response the confirmed ORR was 58%.

BBO-8520 targets both the active (“on”) and inactive (“off”) states of KRAS G12C, whereas approved drugs such as Amgen’s Lumakras and Bristol Myers Squibb’s Krazati target only the off state. In trials supporting accelerated approval in second-line NSCLC, Lumakras produced a 36% ORR and Krazati 43%. Revolution Medicines’ elironrasib, which also targets the on state, has reported a 56% ORR in a similar setting and is further advanced clinically.

BridgeBio also presented early results for BBO-8520 combined with Keytruda. Among eight patients (treatment‑naive and treatment‑experienced), five achieved partial responses: 3 of 3 in the treatment‑naive cohort and 2 of 5 in the treatment‑experienced cohort, the latter of whom had prior KRAS G12C inhibitor therapy. Responses were seen across PD‑L1 expression levels, including two responses in patients with 1–2% PD‑L1. There was one grade 3 elevation in liver enzymes; the company attributed this to co‑medications, reported the event resolved, and said the patient remained on therapy.

Combining KRAS G12C inhibitors with checkpoint inhibitors has previously been challenging because of liver toxicity, notably disrupting plans for a Lumakras/checkpoint inhibitor regimen. BridgeBio said BBO-8520’s therapeutic index could alleviate this issue, but cautioned that the current combination data are very preliminary.

Investors reacted positively to the update, pushing BBOT shares up about 4% on Wednesday. BridgeBio plans another BBO-8520 update in the second half of 2026 and intends to test the compound in combination with its PI3Kα:RAS breaker BBO-10203. All findings remain preliminary and will need confirmation in larger trials.