Inhibrx Provides Clinical Update on Ozekibart (INBRX-109) in Late Line Colorectal Cancer

Rhea-AI Summary

Inhibrx (Nasdaq: INBX) reported updated Phase 1/2 interim data for ozekibart (INBRX-109) plus FOLFIRI in late-line colorectal cancer as of April 10, 2026. In 45 evaluable patients the ORR was 20%, median PFS 5.5 months, and DCR 87%; ~42% were progression-free at six months.

The combination showed a manageable safety profile dominated by Grade 1–2 diarrhea, fatigue, and nausea. Inhibrx plans FDA meetings in H2 2026 and submitted a BLA for chondrosarcoma in April 2026.

Positive

• ORR 20% in 45 evaluable late-line CRC patients
• DCR 87% indicating high tumor growth control
• Median PFS 5.5 months with 42% progression-free at 6 months
• BLA submitted for ozekibart in conventional chondrosarcoma (April 2026)

Negative

• Data from a small early-phase cohort of 45 evaluable patients
• Safety includes common TEAEs (diarrhea, fatigue, nausea) typical of FOLFIRI

News Market Reaction – INBX

+36.88% 1.7x vol

46 alerts

+36.88% Session close to close

+91.0% Peak in 17 hr 8 min

$2.24B Market Cap

1.7x Rel. Volume

In the Apr 22 session, INBX gained 36.88%, reflecting a significant positive market reaction. Argus tracked a peak move of +91.0% during that session. Our momentum scanner triggered 46 alerts that day, indicating elevated trading interest and price volatility. Trading volume was above average at 1.7x the daily average, suggesting increased trading activity.

Data tracked by StockTitan Argus on the day of publication.

Market Context

The stock surged +36.9% in the session following this news. A strong positive reaction aligns with t...

Analysis

The stock surged +36.9% in the session following this news. A strong positive reaction aligns with the pattern where clearly favorable ozekibart data have supported upside, as seen after the Oct 23, 2025 ChonDRAgon readout. Investors have previously rewarded statistically meaningful efficacy and disease control. However, with prior earnings events triggering pullbacks and a short interest of 23.09% (days to cover 8.58), squeezes and position unwinds could both amplify and later retrace moves as sentiment shifts.

Key Figures

Evaluable patients: 45 patients Fourth-line therapy use: 70% of patients Prior irinotecan regimens: 80% of patients +5 more

8 metrics

Evaluable patients 45 patients Phase 1/2 late-line colorectal cancer cohort

Fourth-line therapy use 70% of patients Received ozekibart as fourth-line therapy

Prior irinotecan regimens 80% of patients Previously progressed on irinotecan-based regimens

Objective Response Rate 20% ORR RECIST v1.1 in 45 evaluable CRC patients

Historical ORR range 1–6% ORR Reported for current standard of care per RECIST v1.1

Median PFS 5.5 months Evaluable late-line colorectal cancer population

Disease Control Rate 87% DCR Partial responses plus stable disease as best response

Liver metastases at baseline 68% of patients Presenting with liver metastases at baseline

Historical Context

5 past events · Latest: Mar 19 (Negative)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Mar 19	Earnings & outlook	Negative	-6.1%	Reported large 2025 net loss and outlined 2026 clinical milestones.
Mar 02	Conference participation	Neutral	-4.1%	Announced upcoming ESMO sarcoma conference presentations for ozekibart data.
Dec 16	Clinical program update	Positive	+1.9%	Provided progress on INBRX-106 trials and ozekibart expansion cohorts.
Nov 14	Earnings & trial win	Positive	+6.0%	Q3 2025 results plus ozekibart meeting registrational endpoint in chondrosarcoma.
Nov 04	Conference lineup	Neutral	+0.3%	Outlined multiple November 2025 scientific presentations for ozekibart and DR5 data.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

INBX has often traded lower on earnings and some neutral events, while clearly positive clinical updates have generally aligned with upward or modestly positive moves.

Recent Company History

Over the last six months, INBX has centered its story on ozekibart (INBRX-109) and INBRX-106. Positive registrational ChonDRAgon data in chondrosarcoma on Oct 23, 2025 and subsequent clinical updates supported the oncology thesis, with expansion cohorts in colorectal cancer and Ewing sarcoma showing encouraging activity. Financial reports on Nov 14, 2025 and Mar 19, 2026 highlighted significant R&D investment and net losses, which coincided with selloffs. The current colorectal cancer update builds directly on the prior late-line ozekibart expansion data outlined in December 2025.

Key Terms

objective response rate, progression-free survival, disease control rate, recist v1.1, +4 more

8 terms

objective response rate medical

"Objective Response Rate (ORR): Efficacy was assessed in 45 evaluable patients..."

The objective response rate (ORR) is the percentage of patients in a clinical trial whose tumors measurably shrink or disappear according to preset rules. Investors use it as a quick, objective signal of a drug’s ability to produce a clear treatment effect—like counting how many plants visibly respond after applying a new fertilizer—and higher ORR can improve odds of regulatory approval, commercial success, and company valuation.

progression-free survival medical

"Progression-Free Survival (PFS): The median PFS for the evaluable population was 5.5 months."

Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.

disease control rate medical

"Disease Control Rate (DCR): The overall disease control rate ... remained robust at 87%."

The disease control rate is the share of patients in a clinical trial whose cancer or condition either shrinks or stops getting worse for a specified period after treatment. Think of it like the percentage of people for whom a treatment hits pause or nudges back the problem rather than letting it progress; higher rates suggest the therapy can meaningfully limit disease, which matters to investors assessing a drug’s potential efficacy and commercial value.

recist v1.1 medical

"resulting in an ORR of 20% per RECIST v1.1 criteria."

RECIST v1.1 is a standardized set of rules used in cancer trials to measure how solid tumors change over time, defining when tumors shrink, grow, or stay the same based on imaging scans. Investors care because these consistent measurements determine key trial results and regulatory decisions—like whether a drug is seen as effective—so RECIST-based outcomes directly affect a therapy’s approval prospects, market potential, and company valuation.

folfiri medical

"ozekibart (INBRX-109) in combination with FOLFIRI in patients with ... colorectal cancer"

FOLFIRI is a chemotherapy combination used to treat certain cancers, made from the drugs fluorouracil (5-FU), leucovorin, and irinotecan — think of it as a three‑ingredient recipe designed to attack cancer cells in different ways. Investors care because its use affects demand for related drugs, influences clinical trial and approval outcomes, and can drive revenue or cost pressures for companies involved in manufacturing, supplying supportive care, or developing competing therapies.

treatment-related adverse events medical

"The most common treatment-related adverse events (TEAEs) were diarrhea, fatigue, and nausea..."

Treatment-related adverse events are harmful or unwanted health effects that doctors or regulators determine were caused by a drug, vaccine, device, or other medical therapy. Investors care because how often and how severe these side effects are can shape regulatory approval, labeling, sales potential and legal risk — similar to how product defects can stop or damage a company's ability to sell an item.

biologics license application regulatory

"Additionally, the Company submitted a Biologics License Application (BLA) to the FDA..."

A biologics license application is a formal request submitted to regulatory authorities seeking approval to market a new biological medicine, such as vaccines or treatments made from living organisms. It is a comprehensive review process that evaluates the safety, effectiveness, and manufacturing quality of the product. For investors, receiving approval signals that a biological therapy can be sold to the public, potentially leading to revenue growth and market success.

ewing sarcoma medical

"accelerated regulatory pathways for ozekibart in fourth-line colorectal cancer and in refractory Ewing sarcoma."

Ewing sarcoma is a rare, aggressive cancer that most often starts in bone or the soft tissue around bones, typically affecting children and young adults. It matters to investors because treatments, clinical trial results, and regulatory decisions for this disease can create significant commercial and financial impact: think of it like a small, high-stakes niche market where a successful new therapy can quickly change a company’s revenue prospects, valuation, and risk profile.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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SAN DIEGO, April 21, 2026 /PRNewswire/ -- Inhibrx Biosciences, Inc. (Nasdaq: INBX) ("Inhibrx" or the "Company"), a clinical-stage biopharmaceutical company focused on developing novel biologic therapeutic candidates, today announced 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).

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: https://app.webinar.net/JqrDlM8B4ak 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.

About Inhibrx Biosciences, Inc.

Inhibrx Biosciences is a clinical-stage biopharmaceutical company focused on developing a broad pipeline of novel biologic therapeutic candidates. Inhibrx Biosciences utilizes diverse methods of protein engineering to address the specific requirements of complex target and disease biology, including its proprietary protein engineering platforms. Inhibrx Biosciences was incorporated in January 2024 as a direct, wholly-owned subsidiary of Inhibrx, Inc. Prior to the sale of Inhibrx, Inc. and the INBRX-101 program to Sanofi S.A., Inhibrx Biosciences acquired certain corporate infrastructure and other assets and liabilities through a series of internal restructuring transactions effected by Inhibrx, Inc. Inhibrx, Inc. also completed a distribution to holders of its shares of common stock of 92% of the issued and outstanding shares of Inhibrx Biosciences. Following such transactions, Inhibrx Biosciences' current clinical pipeline of therapeutic candidates includes ozekibart and INBRX-106, both of which utilize multivalent formats where the precise valency can be optimized in a target-centric way to mediate what we believe to be the most appropriate agonist function. For more information, please visit www.inhibrx.com.

Forward-Looking Statements

Inhibrx cautions you that statements contained in this press release regarding matters that are not historical facts are forward-looking statements. These statements are based on Inhibrx's current beliefs and expectations. These forward-looking statements include, but are not limited to, statements regarding: Inhibrx's judgments and beliefs regarding the strength of Inhibrx's pipeline; statements regarding the safety and efficacy of its therapeutic candidate, ozekibart, based on topline and interim results; the potential for ozekibart to be used for the treatment of CRC, Ewing sarcoma and solid tumor indications; the clinical development of ozekibart, including expected enrollment in the expansion cohort, data readouts, regulatory submissions and interactions, and the timing thereof; and any presumption that topline, interim or preliminary data will be representative of final data or data in later clinical trials. Actual results may differ from those set forth in this press release due to the risks and uncertainties inherent in Inhibrx's business, including, without limitation, risks and uncertainties regarding: topline data may not accurately reflect the complete results of a particular study or trial and remain subject to audit, and final data may differ materially from topline data; the initiation, timing, progress and results of its preclinical studies and clinical trials, and its research and development programs; its ability to advance therapeutic candidates into, and successfully complete, clinical trials; its interpretation of topline, interim or preliminary data from its clinical trials, including interpretations regarding disease control and disease response; results from preclinical studies or early clinical trials not necessarily being predictive of future results; unexpected adverse side effects or inadequate efficacy of its therapeutic candidates that may limit their development, regulatory approval and/or commercialization; the potential for its programs and prospects to be negatively impacted by developments relating to its competitors, including the results of studies or regulatory determinations relating to its competitors; the timing or likelihood of regulatory filings and approvals and regulatory developments in the U.S. and foreign countries; the successful commercialization of its therapeutic candidates, if approved; an accelerated development or approval pathway may not be available for ozekibart or other therapeutic candidates and any such pathway may not lead to a faster development process; it may not realize the benefits associated with orphan drug designation, including that orphan drug exclusivity may not effectively protect a product from competition and that such exclusivity may not be maintained; the pricing, coverage and reimbursement of its therapeutic candidates, if approved; its ability to utilize its technology platform to generate and advance additional therapeutic candidates; and other risks described from time to time in the "Risk Factors" section of its filings with the U.S. Securities and Exchange Commission, including those described in its Annual Report on Form 10-K, its Quarterly Reports on Form 10-Q, and supplemented from time to time by its Current Reports on Form 8-K as filed from time to time. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Inhibrx undertakes no obligation to update these statements to reflect events that occur or circumstances that exist after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

Investor and Media Contact:

Kelly Deck, CFO
ir@inhibrx.com
858-795-4260

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SOURCE Inhibrx Biosciences, Inc.

FAQ

What efficacy did INBX report for ozekibart (INBRX-109) in late-line colorectal cancer on April 21, 2026?

The company reported a 20% ORR in 45 evaluable patients, plus a 87% DCR. According to the company, median PFS was 5.5 months with 42% progression-free at six months, including durable responses beyond six months.

How tolerable was ozekibart with FOLFIRI in the INBX April 2026 update?

Ozekibart plus FOLFIRI maintained a manageable safety profile, mainly Grade 1–2 events. According to the company, most treatment-related adverse events were diarrhea, fatigue, and nausea, consistent with known FOLFIRI toxicities.

What regulatory steps did Inhibrx announce for ozekibart in April 2026 for INBX shareholders?

Inhibrx plans to meet the FDA in the second half of 2026 to discuss a first-line registrational trial and accelerated pathways. According to the company, a BLA for chondrosarcoma was submitted in April 2026.

Does the April 21, 2026 INBX update suggest responses across mutation subtypes in CRC?

Yes — responses were reported irrespective of RAS/RAF mutation status in the evaluable cohort. According to the company, nearly half of responses were durable, lasting more than six months.

How many INBX patients remained on therapy and how does that affect durability signals?

Nine patients remained on therapy at cutoff, supporting durability signals beyond median PFS. According to the company, this contributed to 42% of patients being progression-free at six months.