Foghorn Therapeutics (FHTX) 8th Annual Targeted Protein Degradation & Induced Proximity Summit summary

Strategic overview and platform progress

• Focused on targeting the chromatin regulatory system, historically considered undruggable, to address hard-to-treat cancers using selective protein degraders.

• Advanced a portfolio of novel programs, including ARID1B, CBP, and EP300 degraders, with a biology-first approach and deep mechanistic understanding.

• Demonstrated ability to selectively drug targets previously inaccessible, leveraging proprietary chemistry and integrated platform capabilities.

• Collaboration with Lilly on FHD-909 (SMARCA2 inhibitor) is progressing in phase 1 trials, with dose escalation ongoing and potential for dose expansion decision in H1 2026.

• Pipeline includes both wholly owned and partnered assets, with multiple programs tracking toward IND-enabling studies in 2026.

ARID1B degrader program

• Achieved robust, selective degradation of ARID1B, a challenging target, with both VHL and cereblon-based degraders showing up to 80% degradation.

• Selective ARID1B degradation spares ARID1A and other BAF complex members, with high proteome-wide selectivity and on-mechanism activity confirmed.

• Targeting ARID1A-mutant cancers, which represent ~5% of all solid tumors, including endometrial, gastric, bladder, and NSCLC.

• In vivo proof-of-concept for ARID1B program is anticipated in 2026.

• Positive industry feedback received at the TPD and Induced Proximity Summit for achieving selective ARID1B degradation.

CBP degrader program

• Selective CBP degrader (CPPD171) demonstrates efficacy in EP300-mutant cancers and ER-positive breast cancer, with complete tumor regression in preclinical gastric cancer models.

• Avoids platelet toxicity seen with dual CBP/EP300 inhibitors, enabling a wider therapeutic window and better combinability.

• Long-acting injectable formulation allows for weekly or biweekly subcutaneous dosing, with IND readiness targeted for 2026.

• Basket trial approach considered for EP300-mutant cancers; separate study likely for ER-positive breast cancer.