On April 21, 2026 Inhibrx Biosciences, Inc. (Nasdaq: INBX) ("Inhibrx" or the "Company"), a clinical-stage biopharmaceutical company focused on developing novel biologic therapeutic candidates, reported updated interim data from its Phase 1/2 study evaluating ozekibart (INBRX-109) in combination with FOLFIRI in patients with locally advanced or metastatic, unresectable colorectal cancer (CRC).
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As of April 10, 2026, the cutoff date, the CRC cohort continued to demonstrate a compelling signal of activity in a heavily pretreated patient population. Of the 45 evaluable patients, approximately 70% received ozekibart as a fourth-line therapy, and 80% had previously progressed on irinotecan-based regimens. The following data were observed as of the cutoff date:
Objective Response Rate (ORR): Efficacy was assessed in 45 evaluable patients, resulting in an ORR of 20% per RECIST v1.1 criteria. Historically, the current standard of care has yielded limited response rates (ORR of 1-6% per RECIST v1.1 criteria). Nearly half of responses were durable with a duration of response exceeding 6 months. Responses were observed irrespective of RAS/RAF mutation status.
Progression-Free Survival (PFS): The median PFS for the evaluable population was 5.5 months. Notably, 42% of patients remained progression-free at the 6-month landmark, with 9 patients remaining on therapy, suggesting that a significant portion of patients achieve durable disease control that extends well beyond the median PFS.
Disease Control Rate (DCR): The overall disease control rate (partial responses and stable disease as best response) remained robust at 87%, further supporting the potential of ozekibart to control tumor growth in a heavily pre-treated population.
Safety and tolerability: Ozekibart in combination with FOLFIRI continues to maintain a manageable safety profile. The most common treatment-related adverse events (TEAEs) were diarrhea, fatigue, and nausea, which were largely Grade 1 or 2 and consistent with the known side effects of FOLFIRI. Despite the majority of the patients (68%) presenting with liver metastases at baseline, no significant liver toxicity was observed.
"The meaningful response rate and PFS, together with a manageable safety profile in this heavily pre-treated population, are highly encouraging and support our plans to advance into first line, where the potential for deeper and more durable responses may be even greater," said Mark Lappe, Chief Executive Officer of Inhibrx Biosciences. "It also highlights the opportunity for broader expansion of ozekibart into other indications, which we continue to explore."
Inhibrx plans to meet with the U.S. Food and Drug Administration (FDA) in the second half of 2026 to discuss plans to initiate a first-line registrational trial in CRC. The Company also plans to discuss with the FDA the potential for accelerated regulatory pathways for ozekibart in fourth-line colorectal cancer and in refractory Ewing sarcoma. Additionally, the Company submitted a Biologics License Application (BLA) to the FDA for ozekibart in conventional chondrosarcoma in April 2026.
The Company will host a live webcast presentation today, April 21, 2026, at 1:30 p.m. Pacific Time to further discuss the results.
About the Conference Call
Investors may join via the web: View Source or may listen to the call by dialing (1-888-880-3330). Please refer to Inhibrx Biosciences, Inc. or the conference ID 9536529 when calling in. Following the webcast, the presentation may be accessed through a link on the "Events and Presentations" section of Inhibrx’s website. The webcast will be available for 60 days following the event. Following the presentation, Inhibrx will also update its corporate presentation within the "Investors" section of its website at www.inhibrx.com.
About ozekibart (INBRX-109)
Ozekibart is a precision-engineered, tetravalent death receptor 5 (DR5) agonist antibody designed to exploit the tumor-biased cell death induced by DR5 activation. In January 2021, the FDA granted Fast Track designation to ozekibart for the treatment of patients with metastatic or unresectable conventional chondrosarcoma, and, in November 2021, the FDA granted orphan drug designation to ozekibart for chondrosarcoma.
In June 2021, Inhibrx initiated a randomized, blinded, placebo-controlled, registrational trial of ozekibart in metastatic, unresectable conventional chondrosarcoma. The trial enrolled a total of 206 patients across 67 different sites worldwide. In October 2025, Inhibrx announced the ChonDRAgon study met its primary endpoint of a statistically significant and clinically meaningful median progression-free survival (PFS) for patients with advanced or metastatic chondrosarcoma treated with ozekibart compared to placebo. Ozekibart achieved a 52% reduction in the risk of disease progression or death compared to placebo (stratified Hazard Ratio [HR] 0.479; 95% CI: 0.33, 0.68); P<0.0001), more than doubling median PFS to 5.52 months versus 2.66 months for placebo. Importantly, ozekibart is the first investigational therapy to demonstrate a significant PFS benefit in a randomized trial for chondrosarcoma, a disease with no approved systemic options.
The benefit of ozekibart was consistent across all pre-specified subgroups, including patients with IDH-wild-type and IDH-mutant tumors. Other key secondary endpoints, including disease control rate (54% vs 27.5%), and delay to deterioration in pain and physical function, further supported the clinical benefit observed with ozekibart.
(Press release, Inhibrx, APR 21, 2026, View Source [SID1234664640])