Preclinical data highlight potential target engagement biomarkers to support clinical evaluation of CBL-B inhibitors

BOSTON, MA, USA I November 3, 2023 I HotSpot Therapeutics, Inc., a biotechnology company pioneering the discovery and development of oral, small molecule allosteric therapies targeting regulatory sites on proteins referred to as “natural hotspots,” today announced the presentation of additional preclinical data from the Company’s Casitas B-lineage lymphoma proto-oncogene (CBL-B) program in a poster presentation at the 2023 Society for Immunotherapy of Cancer (SITC) Annual Meeting.

“Our enthusiasm for the therapeutic potential of HST-1011, a potential best-in-class CBL-B inhibitor, is partly driven by our belief that it can drive single-agent biological activity,” said Timothy Reilly, Ph.D., Chief Development Officer of HotSpot. “Understanding which peripheral biomarkers are associated with this biology and the reliability of their measurement is critical to our characterization of of HST-1011’s activity in patients as we advance our ongoing Phase 1/2 study.” 

The presentation describes preclinical data in which HotSpot CBL-B inhibitors were evaluated in both in vitro and in vivo settings to identify and then characterize a repertoire of potential proximal biomarkers of CBL-B inhibitory activity. Several proteins, including phosphorylated ZAP70, Notch1 and IGF1R, showed robust dose-dependent effects and were further assessed for their reliability and potential feasibility for use in a clinical setting. The results provide support for their potential use in evaluating HST-1011 in our ongoing Phase 1/2, open-label, clinical study designed to evaluate HST-1011 alone and subsequently in combination with Regeneron’s anti-PD-1 therapy, Libtayo® (cemiplimab), in patients with advanced solid tumors that are relapsed on or are refractory to anti-PD(L)-1 or standard of care therapies. Information on this clinical trial can be found on (NCT05662397).

About HST-1011
HST-1011 is an investigational orally bioavailable, selective, small molecule allosteric inhibitor of CBL-B, an E3 ubiquitin protein ligase critically involved in immune cell response. Because CBL-B functions as a master regulator of effector cell (T cell and natural killer cell) immunity, its inactivation removes its endogenous negative regulatory functions to substantially enhance anti-tumor immunity. Preclinical data has demonstrated HST-1011’s ability to bind to and inhibit a natural hotspot on CBL-B, yielding the activation and propagation of a targeted anti-tumor immune response. Enabled by HotSpot’s proprietary Smart Allostery™ platform, HST-1011 is designed with tight binding, low nanomolar potency, a slow dissociation rate from the target to enable sustained pharmacology, and greater selectivity for CBL-B relative to C-CBL.

About HotSpot Therapeutics, Inc.
HotSpot Therapeutics, Inc. is pioneering a new class of allosteric drugs that target certain naturally occurring pockets on proteins called “natural hotspots.” These pockets are decisive in controlling a protein’s cellular function and have significant potential for new drug discovery by enabling the systematic design of potent and selective small molecules with novel pharmacology. The Company’s proprietary Smart Allostery™ platform combines computational approaches and AI-driven data mining of large and diverse data sets to uncover hotspots with tailored pharmacology toolkits and bespoke chemistry to drive the rapid discovery of novel hotspot-targeted small molecules. Leveraging this approach, HotSpot is building a broad pipeline of novel allosteric therapies for the treatment of cancer and autoimmune diseases. To learn more, visit

SOURCE: HotSpot Therapeutics