Hello, and thank you for standing by. My name is Regina, and I will be your conference operator today. At this time, I would like to welcome everyone to the Inhibrx report's positive top-line results from its registrational trial of ozekibart in chondrosarcoma and provides updates on colorectal cancer and Ewing sarcoma expansion cohort's conference call. All lines have been placed on mute to prevent any background noise. If you should need assistance during the call, press star, then zero, and an operator will come back online to assist you. I'd now like to turn the conference over to Mark Lappe, CEO. Please go ahead.
Thank you, everyone, for joining the call this afternoon. This is Mark Lappe, the CEO and one of the founders of Inhibrx. Earlier today, we shared the top-line results from ChonDRAgon, our registrational trial with ozekibart, our tetravalent DR5 agonist, as a single agent in patients with unresectable or metastatic chondrosarcoma. We also provided an update on the colorectal and Ewing sarcoma combination cohorts. We are excited and encouraged by these results, which suggest the potential of ozekibart to expand not only in sarcomas but also in high unmet need solid tumor indications. It marks a significant milestone for our company and, most importantly, for patients who currently have either no or very limited treatment options. Before proceeding, I would like to remind you that during our call today, we will be making several forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.
These forward-looking statements include goals, beliefs, expectations, plans, prospects, timing of events, and future results, are based on current information, assumptions, and expectations that are inherently subject to change and involve several risks and uncertainties that may cause results to differ materially. These factors and other risks associated with our business can be found in our filings made with the SEC. You are cautioned not to place undue reliance on these forward-looking statements, which are made only as of today's date, and we assume no obligation to update or revise these forward-looking statements as circumstances change except as required by law. Now that that's out of the way, we will first discuss the results from ChonDRAgon . As many of you know, conventional chondrosarcoma is a rare type of bone cancer that's notoriously resistant to both chemotherapy and radiation.
Surgical resection is the only curative treatment for localized chondrosarcoma, but there are no treatments approved for patients with unresectable or metastatic disease, and the patients have poor prognosis. This study was a randomized, blinded registrational labeling study designed to evaluate the efficacy, safety, and tolerability of ozekibart versus placebo in patients with unresectable or metastatic disease. The primary endpoint was progression-free survival, and patients were required to have disease progression within six months prior to screening, which is the most rapidly progressing chondrosarcoma population. The patients that will be eligible for ozekibart treatment include not only the rapid progressing population but also the moderately to slowly progressing populations as well. Patients treated with ozekibart showed a median PFS of 5.52 months compared to 2.66 months in the placebo group, more than doubling PFS.
The hazard ratio was 0.479, representing a 52% reduction in the risk of progression or death, and the p-value was less than 0.0001. Additionally, the benefit of ozekibart was consistent across all pre-specified subgroups, including patients with IDH wild type and IDH mutant tumors. The disease control rate for ozekibart was 54% versus 27.5% in the placebo arm. Additionally, a delay in time to deterioration was observed in pain and physical function as compared to the control group, further supporting the clinical benefit observed. O zekibart was generally well tolerated with a manageable safety profile. The most common treatment-related adverse events were fatigue, constipation, and nausea. Hepatotoxicity, a known risk for this mechanism of action, occurs during the first treatment cycle and is in patients with underlying hepatic impairment. One hepatotoxicity-related fatal event occurred early in the study prior to the implementation of mitigation measures.
Over the course of the ChonDRAgon study, this risk was effectively mitigated by excluding patients with severe liver impairment and by implementing close monitoring during early treatment cycles, allowing for prompt management of liver enzyme elevations. This approach resulted in a low overall incidence of treatment-related hepatic adverse events, 11.8% compared to 4.5% in the placebo arm, and the majority of these events were just Grade 1 and Grade 2 in severity. Based on these compelling results, we plan to file a BLA in the second quarter of 2026. We plan to present data in more detail at CTOS on November 14th. Moving next to colorectal cancer. Based on initial results from the phase I trial of o zekibart in combination with FOLFIRI for the treatment of advanced or metastatic unresectable colorectal cancer, or CRC, Inhibrx initiated an expansion cohort enrolling 44 patients.
This was the fourth- line of treatment for approximately 70% of patients and the third- line of treatment for approximately 30% of patients. Notably, 80% of these patients had been previously treated with regimens containing irinotecan. Of the 26 evaluable patients or those who had at least one post-baseline scan, we observed a 23% overall confirmed response rate and an overall disease control rate of 92%. These results are highly encouraging in a heavily pretreated CRC population, where responders are rare. The current standard of care only delivers a 6% response rate in the third-line setting. O zekibart in combination with FOLFIRI was well tolerated. The most common treatment-emergent adverse events included anemia, diarrhea, nausea, and fatigue, the majority being low grade and consistent with the known side effects of FOLFIRI. This now brings us to Ewing sarcoma.
Based on initial results from the phase I trial of o zekibart in combination with irinotecan and temozolomide for advanced or metastatic unresectable relapsed or refractory Ewing sarcoma, Inhibrx initiated an expansion cohort, which is expected to enroll up to 50 patients, including pediatric patients. Of the 33 patients recruited to date, more than 1/2 were third or fourth-line patients. Among the 25 evaluable patients to date, we've observed a 64% overall response rate and a disease control rate of 92%, with most patients experiencing measurable tumor reduction. Compared with the 15%- 30% response rate typically observed with irinotecan and temozolomide alone, these outcomes are highly encouraging and highlight the potential of o zekibart to provide meaningful benefit in this difficult-to-treat population. Overall, o zekibart in combination with irinotecan and temozolomide was well tolerated.
The most common adverse events were diarrhea, nausea, anemia, and fatigue, all consistent with the known safety profile of irinotecan and temozolomide. I also wanted to provide some background on the market opportunity for o zekibart . Our commercial team has conducted an in-depth assessment of the epidemiology and total addressable market for each of these indications, and I will now briefly walk you through those findings. First, chondrosarcoma. The prevalence of metastatic or unresectable chondrosarcoma is estimated to be 2,000 to 3,000 patients in the U.S. alone. There are currently no available FDA-approved treatment options for these patients. If approved, we believe we could achieve significant market share and pricing comparable to other rare oncology drugs, and we estimate global peak revenue could exceed $500 million in the metastatic and unresectable population. Second, colorectal cancer.
The annual incidence of CRC in the third- line or later is estimated to be 20,000 to 30,000 patients in the U.S. Given this high unmet need and large number of patients, we believe that if approved for this indication, the total commercial opportunity has the potential to exceed $1.5 billion in the late line setting in the U.S. alone, with the potential to move up to first line in the future, representing a $3.5 billion U.S. peak sales opportunity in the RAS wild type population. Finally, Ewing sarcoma, which in the second line or later presents a commercial opportunity similar to metastatic or unresectable chondrosarcoma. The prevalence of relapsed or refractory Ewing's is estimated to be around 3,000 patients in the U.S., and only chemotherapy with limited response rates is available as a treatment option.
If approved for this indication, we believe we could achieve significant market share, and we estimate the global peak revenue could exceed $500 million. In total, chondrosarcoma, late line CRC, and Ewing sarcoma have a combined market potential of greater than $2.5 billion. We are also very excited about our recent preclinical data in glioblastoma, which you can find in our latest investor deck on our website, which, if translated clinically and subject to regulatory approval, could represent a U.S. market opportunity of greater than $1 billion. We believe there are many expansion opportunities, such as first line CRC, glioblastoma, the perioperative Ewing and chondrosarcoma settings, among others, that can grow this drug into a much larger peak sales opportunity. We believe this program can offer high commercial synergy to existing pharmaceutical portfolios and infrastructures.
Our goal is to transact on this program by putting it in the hands of a third party in order to bring the utmost value to shareholders with a focus on tax efficiency and dilution sensitivity. We are actively engaged in conversations with StrategyX and are optimistic about the progress of those discussions thus far. DR5 has long been a validated and promising target with the potential to benefit many difficult-to-treat tumor indications. As confirmed by the numerous failed efforts over the last two decades, it has also proved to be a very challenging target to drug properly. We are excited that o zekibart may have finally unlocked the potential to be the first in class DR5 agonist.
I want to commend the entire team at Inhibrx for their perseverance and commitment to excellence on this program, and also want to extend our gratitude to the investigators, the patients, and their families who participated in our o zekibart trials. Thank you again for taking the time to listen to this call, and please reach out to set up a meeting if you have any questions.
That will conclude today's meeting. Thank you all for joining. You may now disconnect.