Founder & Dirs Buy $3.5M After Positive Clinical Data at Inhibrx

Inhibrx Biosciences, Inc. (INBX:US) is a clinical-stage biopharmaceutical company focused on developing novel biologic therapeutic candidates for life-threatening conditions, including cancer. Its pipeline features candidates such as INBRX-106 (an OX40 agonist) and ozekibart (INBRX-109). As of early September 2026, Inhibrx has a market capitalization of approximately $1.7 billion.

Recent Insider Trades

Insider activity at Inhibrx turned strongly positive on September 8, 2026, with the Founder and two directors making open-market purchases totaling approximately $3.5 million. These mark the first insider buys at the company since 2024:

• Mark P. Lappe (Founder) purchased 25,000 shares at an average price of approximately $105.82 for $2.646 million, increasing his holdings to 730,548 shares.

• Jon Faiz Kayyem (Director) bought 5,000 shares at $113.52 for $567,698, raising his holdings to 424,360 shares.

• Douglas Gorman (Doug) Forsyth (Director) acquired 2,500 shares at $114.65 for $286,677, increasing his holdings to 227,064 shares.

The Founder’s substantial $2.65 million purchase, combined with meaningful director investments on the same day, carries significant weight. These being the first open-market buys since 2024 further underscores the strength of the internal conviction at current levels.

Clinical Results

On September 8, 2026, the same day as the insider purchases, Inhibrx announced positive primary endpoint results from the randomized Phase 2 portion of its HexAgon study evaluating INBRX-106 in combination with pembrolizumab (Keytruda) versus pembrolizumab alone in first-line head and neck squamous cell carcinoma (HNSCC).

The combination nearly doubled the confirmed objective response rate (48.3% vs. 26.5%) and showed a median progression-free survival of 9.6 months versus 4.9 months for Keytruda alone. Results were particularly strong in HPV-positive patients. The company plans to expand the study and is exploring a potential pathway to accelerated approval.

Overall, this significant founder- and director-led cluster buy of approximately $3.5 million, the first since 2024, is a strong positive signal, reflecting high internal confidence in Inhibrx’s clinical progress and long-term prospects following the encouraging Phase 2 data.