Erasca, Inc. 8-K

What Happened
Erasca announced on April 27, 2026 that preliminary Phase 1 dose‑escalation data for its pan‑RAS molecular glue ERAS‑0015 were positive across its U.S. AURORAS‑1 trial and Joyo’s China trial (JYP0015M101). Key clinical findings include a well‑behaved pharmacokinetic (PK) profile up to the maximum administered dose (MAD) of 40 mg once daily (QD), a pharmacologically active dose (PAD) range of 16–32 mg QD, and selection of 24 mg and 32 mg QD as recommended doses for expansion (RDEs). Pharmacodynamic (PD) data showed substantial KRAS G12X circulating tumor DNA (ctDNA) reductions (14/14 patients had ≥75% reduction, 5/14 had 100% reduction). Reported efficacy signals: NSCLC at PADs showed 62% unconfirmed ORR at 8 weeks (uORR8wk, N=37) in 2L+ KRAS G12X NSCLC and 75% uORR8wk (N=16) in post‑ICI/platinum patients; PDAC showed 40% uORR14wk (N=20) in 2L KRAS G12X PDAC. Safety was generally manageable with mostly low‑grade adverse events, no dose‑limiting toxicities (DLTs) reported in escalation, but one Grade 5 pneumonitis death was reported in a patient who received 24 mg.

Key Details

• PK/PD: PAD 16–32 mg QD; MAD 40 mg QD; 100% (14/14) of evaluated patients had ≥75% reduction in KRAS G12X ctDNA.
• Efficacy (pooled/early): NSCLC 62% uORR8wk (N=37) at PADs; NSCLC post‑ICI/platinum 75% (N=16); PDAC 40% uORR14wk (N=20) at PADs. RDEs selected at 24 mg and 32 mg QD.
• Safety: Generally well tolerated, low rates of dose changes for treatment‑related AEs; one Grade 5 pneumonitis after withdrawal of supportive care; no DLTs through the 31Mar2026 combination data cut-off (combo N=3).
• Milestones: U.S. monotherapy expansion and combination dose‑escalation cohorts initiated in Q1–Q2 2026; AURORAS‑1 expansion/combo data expected H1 2027. BOREALIS‑1 (ERAS‑4001) preliminary data expected H2 2026.

Why It Matters
For investors, these results represent an early but potentially meaningful clinical signal for ERAS‑0015 in multiple hard‑to‑treat KRAS‑mutant cancers (NSCLC, PDAC, CRC). The combination of clear PK/PD activity, objective responses at selected dose ranges, and planned expansion cohorts could de‑risk near‑term clinical development if results hold up in larger cohorts. However, the company stresses these are preliminary, pooled and cross‑study comparisons are limited, and outcomes may change as enrollment continues and data mature (see filing for forward‑looking risk cautions).