Ozekibart's 52% Risk Cut Drives 70% Surge as Liver Risks Loom

Inhibrx Biosciences (NASDAQ:INBX) shares surged over 70% in after-hours trading on October 23, 2025, following the release of positive Phase 2 trial results for its experimental cancer drug ozekibart (INBRX-109) in the treatment of chondrosarcoma, a rare and aggressive bone cancer with no approved systemic therapies, according to an Investing.com report. The ChonDRAgon study, which evaluated ozekibart as a monotherapy versus placebo, met its primary endpoint, demonstrating a statistically significant 52% reduction in the risk of disease progression or death compared to the control group. Patients receiving ozekibart achieved a median progression-free survival (PFS) of 5.52 months, more than double the 2.66 months observed in the placebo cohort. The drug also showed a 54% disease control rate versus 27.5% for placebo, with consistent benefits across all pre-specified subgroups, according to a Tokenist article.

The safety profile of ozekibart was generally manageable, though hepatotoxicity emerged as a key concern. Early in the trial, one fatal liver-related event occurred, prompting mitigation strategies such as excluding patients with severe liver impairment and implementing close monitoring during initial treatment cycles. These measures reduced the incidence of treatment-related hepatic adverse events to 11.8% in the ozekibart group compared to 4.5% in the placebo arm, with most events classified as mild or moderate, as noted in a StreetInsider release.

Beyond chondrosarcoma, Inhibrx reported promising interim data from expansion cohorts testing ozekibart in combination therapies for colorectal cancer and Ewing sarcoma. In heavily pretreated colorectal cancer patients, the drug combined with FOLFIRI chemotherapy achieved a 23% overall response rate and 92% disease control rate. For Ewing sarcoma, ozekibart paired with irinotecan and temozolomide demonstrated a 64% overall response rate and 92% disease control rate, reported by Investing.com. These findings suggest potential broader applications for the therapy in oncology.

The company plans to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration in the second quarter of 2026, per Investing.com. Detailed results from the ChonDRAgon trial are scheduled for presentation at the Connective Tissue Oncology Society Annual Meeting on November 14, 2025, according to Tokenist.

Market reaction to the news was robust, with INBX stock jumping from $28.36 on October 23 to $46.30 in pre-market trading the following day—a 63.26% gain, according to Tokenist. The surge followed a prior session's 10% decline, reflecting volatility typical of biotech stocks. Trading volume spiked to 1.15 million shares, far exceeding the average volume of 151,435, per Tokenist. Retail investor sentiment on platforms like Stocktwits also turned "extremely bullish," with message volume surging 985% in 24 hours, as shown on Stocktwits.

Financially, Inhibrx operates with a market capitalization of approximately $457 million and holds strong liquidity, with a current ratio of nearly 5, according to an Investing.com story. However, the company reported a net loss of $28.65 million for the most recent quarter, driven by heavy research and development expenses, according to Timothy Sykes. Despite these losses, analysts highlight the potential for ozekibart to become a revenue-generating asset if regulatory approval is secured.

The stock's year-to-date rally of 140% underscores investor optimism, though some caution that commercial success remains contingent on navigating regulatory hurdles and demonstrating long-term efficacy. With no approved treatments for chondrosarcoma, ozekibart's potential first-mover advantage has drawn comparisons to breakthrough therapies in niche oncology markets, according to Stocktwits.