📰 What This Document Is 📄

This 8-K filing is a Current Report, meaning Inhibrx Biosciences is providing an immediate, detailed update to the public about major developments, specifically clinical trial data. Since the company is developing complex biologics, investors need to know about the progress of their drug candidates.

👉 The core message is extremely positive: the company is presenting compelling, supportive data from two separate programs—one for colorectal cancer (CRC) and one for chondrosarcoma—and is outlining specific steps to move toward FDA approval for both.

🏥 What The Company Does 🧬

In simple terms, Inhibrx is a clinical-stage biopharmaceutical company. It doesn't sell finished drugs; instead, it focuses on developing novel therapeutic proteins (biologics) that target specific parts of disease biology.

👉 The company uses proprietary protein engineering platforms and diverse scientific methods to build drugs like ozekibart. Its goal is to treat serious diseases for which current treatments are limited or ineffective.

🔬 Ozekibart’s Scientific Role 🛠️

Ozekibart (INBRX-109) is the company’s primary drug candidate discussed in this update. Understanding its mechanism helps readers understand its potential power.

👉 Ozekibart is a "precision-engineered, tetravalent death receptor 5 (DR5) agonist antibody." This complex terminology simply means it is an antibody designed to activate a specific cell-death signal (DR5) within tumors, making the cancer cells die.

Key Developmental Milestones

• Fast Track/Orphan Status: The FDA granted Fast Track designation for ozekibart in conventional chondrosarcoma in January 2021, and Orphan Drug designation in November 2021.
  • Why it matters: These designations mean the FDA recognizes the drug for rare or life-threatening diseases and may provide an accelerated path toward approval.
• Pipeline: In addition to ozekibart, the company’s current pipeline includes another candidate, INBRX-106.
  • Why it matters: The company isn't relying on just one drug; having a diverse pipeline reduces risk.

🍎 CRC Clinical Update: Ozekibart in Colorectal Cancer 📊

This section details the updated interim data from a Phase 1/2 study, focusing on Ozekibart combined with FOLFIRI for locally advanced or metastatic, unresectable colorectal cancer (CRC). This is the most immediate signal for the company.

👉 This data was gathered from a heavily pretreated patient group—meaning the cancer was advanced and previous standard treatments had already failed.

Performance Metrics (As of April 10, 2026, cutoff date):

• Objective Response Rate (ORR): The ORR was 20% across 45 evaluable patients.
  • Why it matters: This is significantly higher than the current standard of care, which typically yields ORR rates of only 1–6% per RECIST v1.1 criteria.
• Durable Responses: Nearly half of the observed responses were durable, lasting more than 6 months.
  • Why it matters: It’s not enough for a drug to just shrink a tumor; sustained responses suggest long-term control, which is highly valuable to patients.
• Disease Control Rate (DCR): The overall DCR remained robust at 87%.
  • Why it matters: This high rate indicates that the drug is very effective at preventing the tumor from growing significantly (stable disease counts).
• Progression-Free Survival (PFS): The median PFS was 5.5 months.
  • Note: The data also highlighted that 42% of patients remained progression-free at the 6-month mark, suggesting prolonged disease control beyond the median.

Safety Profile and Tolerability

• Tolerability: Ozekibart maintained a manageable safety profile. The most common issues were diarrhea, fatigue, and nausea, which were mostly Grade 1 or 2 (mild to moderate).
• Liver Safety: Crucially, despite 68% of patients presenting with liver metastases at baseline, no significant liver toxicity was observed.
  • Why it matters: This addresses a major concern in CRC treatment and suggests that the combination treatment can be safely administered even when the disease is advanced and widespread.

🏆 Chondrosarcoma Program Update (ChonDRAgon Study) 🦴

This section presents data from a separate, earlier trial for chondrosarcoma (a rare bone cancer), demonstrating the drug's proven benefit in a controlled setting.

👉 The standout finding is that ozekibart proved superior to placebo in a large, randomized trial, establishing a strong clinical anchor for this indication.

Key Findings from the ChonDRAgon Study (October 2025):

• Primary Endpoint: The study successfully met its primary endpoint for median progression-free survival (PFS).
• Survival Improvement: Ozekibart achieved a 52% reduction in the risk of disease progression or death compared to placebo.
  • The Metric: This is quantified by a Stratified Hazard Ratio (HR) of 0.479.
• Median PFS Comparison: The drug more than doubled the median PFS, achieving 5.52 months versus 2.66 months for the placebo group.
  • Why it matters: Doubling the time before the disease progresses is a highly significant clinical outcome.
• Consistency: The benefit was consistent across all pre-specified subgroups, including both IDH-wild-type and IDH-mutant tumors, broadening the drug's potential use.

🚀 Future Regulatory Plans and Guidance 🎯

Inhibrx has used these positive data points to set a clear, aggressive roadmap for regulatory approval and market expansion.

👉 The company plans to use these positive findings to secure formal meetings with the FDA to solidify its development strategy.

Planned FDA Engagements:

• First-Line CRC: The company plans to meet with the FDA in the second half of 2026 to discuss initiating a first-line (earlier treatment stage) registrational trial for CRC.
• Accelerated Pathways: They also plan to discuss accelerated regulatory pathways for both fourth-line CRC and refractory Ewing sarcoma.
• BLA Submission: The company officially submitted a Biologics License Application (BLA) to the FDA for ozekibart in conventional chondrosarcoma in April 2026.

Executive Commentary

Mark Lappe, CEO of Inhibrx Biosciences, summarized the findings' impact by stating: "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."

• Implication: The CEO is explicitly setting the expectation for the next stage—advancing from late-line (4th-line) to first-line treatment, which represents a major step up in clinical value.

🏢 Corporate Structure and History 💼

This section provides background context on the company's legal status and history, which is typical for a biopharma filing after significant corporate restructuring.

👉 The company has undergone significant changes since its inception, which affects its current legal structure and ownership.

Corporate Status

• Incorporation: Inhibrx Biosciences was incorporated in January 2024.
• Background: It operates as a direct, wholly-owned subsidiary of Inhibrx, Inc.
• Prior Transactions: The corporate structure was formed through internal restructuring, including the prior sale of Inhibrx, Inc. and the INBRX-101 program to Sanofi S.A.
  • Why it matters: While complex, knowing the company has successfully navigated these transactions indicates operational stability, even if the structure is complicated.

🗓️ Key Event Dates and Contacts 🌐

If you want to dive deeper into the data or ask questions, this section lists the critical follow-up resources.

👉 Investors are encouraged to attend a live webcast to get a detailed presentation of the results.

Event Details

• Webcast Date & Time: Today, April 21, 2026, at 1:30 p.m. Pacific Time.
• Webcast Link: https://app.webinar.net/JqrDlM8B4ak
• Phone Call: Investors can also dial (1-888-880-3330) and refer to Inhibrx Biosciences, Inc. or the conference ID 9536529.
• Contact: For immediate investor questions, the CFO, Kelly Deck, can be reached at [email protected] or 858-795-4260.

🧠 The Analogy 🗽

Think of a drug like Ozekibart like a high-powered weed killer (the drug) for a stubborn, resistant weed (the cancer). Most existing treatments are basic, weaker sprays that only kill the top growth, leaving the roots intact (low ORR of 1-6%). Ozekibart, however, works by targeting a specific vulnerability (the DR5 receptor) that is unique to the weed. By finding this single, powerful point of failure, the drug can systematically kill the entire plant, leading to deeply durable and powerful results (20% ORR, 5.5 months PFS).

🧩 Final Takeaway 🚀

Inhibrx provided highly encouraging clinical data for Ozekibart in late-line CRC (ORR 20%, PFS 5.5 months) and showcased strong historical success in chondrosarcoma. The company is translating these positive results into a clear, aggressive development plan aiming for first-line CRC and continued regulatory advancement for both indications.