Erasca Announces Positive Preliminary Phase 1 Dose Escalation Data for Potentially Best-in-Class Pan-RAS Molecular Glue ERAS-0015 in KRAS-Mutant Solid Tumors

Robust monotherapy efficacy in KRAS G12X NSCLC: 62% uORR in 2L+ and 75% uORR in post-ICI/platinum 2/3L at 16-32 mg QD PAD, and 64% uORR in 2L+ at 24-32 mg QD RDE

Robust monotherapy efficacy in 2L KRAS G12X PDAC: 40% uORR at 16-32 mg QD PAD, 42% uORR at 24-32 mg QD RDE, and 50% uORR at 32 mg QD

Monotherapy generally well-tolerated with mostly low-grade AEs, no DLTs as of DCO, and low rate of dose reductions and no discontinuations due to TRAEs

Preliminary data suggest ERAS-0015 may combine safely with standard-of-care doses of panitumumab with no DLTs as of DCO (N=3) and 1/1 uPR in CRC

Well-behaved PK, with dose-dependent increase in PK exposure up to MAD of 40 mg QD and no exposure plateau observed

Anticipated data disclosure of select ERAS-0015 monotherapy dose expansion and combination dose escalation cohorts narrowed to H1 2027

Conference call and live webcast today at 4:30 PM Eastern Time

SAN DIEGO, April 27, 2026 (GLOBE NEWSWIRE) -- Erasca, Inc. (NASDAQ:ERAS), a clinical-stage precision oncology company singularly focused on discovering, developing, and commercializing therapies for patients with RAS/MAPK pathway-driven cancers, today announced positive preliminary Phase 1 dose escalation data for its potentially best-in-class, pan-RAS molecular glue ERAS-0015 in patients with RAS-mutant solid tumors.

The preliminary data are from Erasca's ongoing AURORAS-1 Phase 1 dose escalation trial in the U.S. and the ongoing JYP0015M101 Phase 1 dose escalation trial in China sponsored by Joyo Pharmatech Co., Ltd. (Joyo), both evaluating ERAS-0015 in patients with RAS-mutant solid tumors.

"We are thrilled with the robust efficacy results demonstrated so far by our pan-RAS inhibitor ERAS-0015 in patients with lung and pancreatic cancer," said Jonathan E. Lim, M.D., Erasca's chairman, CEO, and co-founder. "The magnitude of clinical benefit seen during dose escalation is particularly striking and compares favorably with other pan-RAS, pan-KRAS, or KRAS-mutant selective inhibitors. This efficacy is accompanied by generally well-tolerated safety results, primarily characterized by manageable, low-grade adverse events. Notably, preliminary data support ERAS-0015 may be combined with standard-of-care doses of panitumumab, positioning it as a potential backbone therapy for future combination regimens. Together, we believe these findings support the best-in-class potential of ERAS-0015, and we look forward to continued progress in our Phase 1 monotherapy dose expansion cohorts and combination dose escalation cohorts."

Highlights of Phase 1 Preliminary Results

• Pharmacokinetics (PK):
  • Well-behaved PK, with dose-dependent increase in PK exposure up to the maximum administered dose (MAD) of 40 mg once daily (QD) and no exposure plateau observed
  • Pharmacologically active dose (PAD) range of 16-32 mg QD defined based on mean steady-state average exposures that exceeded target exposure threshold (based on the insensitive xenograft model)
• Pharmacodynamics (PD):
  • Substantial reductions in KRAS G12X circulating tumor DNA (ctDNA) were observed at the PAD doses (16-32 mg QD), with 100% of patients (14/14) showing at least 75% reduction in KRAS G12X variant allele fraction, including 5 out of 14 patients showing 100% reduction
• Efficacy: Robust monotherapy overall response rates (ORR) in patients with KRAS G12X non-small cell lung cancer (NSCLC) and with KRAS G12X pancreatic cancer (PDAC), in each case as of the relevant data cutoff (DCO)^1,2:
  • NSCLC
    • At PADs of 16-32 mg QD, 62% uORR_8wk (N=37) in second line or greater (2L+) KRAS G12X NSCLC, which exceeded comparator by 24 percentage points^3,4
    • At PADs of 16-32 mg QD, 75% uORR_8wk (N=16) in post-ICI/platinum (2/3L) KRAS G12X NSCLC, which exceeded comparator by 37 percentage points^3,4
    • At recommended doses for expansion (RDEs) of 24-32 mg QD, 64% uORR_8wk (N=25) in 2L+ KRAS G12X NSCLC³
  • PDAC
    • At PADs of 16-32 mg QD, 40% uORR_14wk (N=20) in 2L KRAS G12X PDAC, which exceeded comparator by 11 percentage points^5,6
    • At RDEs of 24-32 mg QD, 42% uORR_14wk (N=12) in 2L KRAS G12X PDAC, which exceeded comparator by 13 percentage points^5,6
    • At RDE of 32 mg QD, 50% uORR_14wk (N=2) in 2L KRAS G12X PDAC, which exceeded comparator by 15 percentage points^5,7
• Multiple ongoing responses: Nearly all responding patients—including all unconfirmed responders—remain on treatment as of the DCO:
  • NSCLC
    • 23 out of 24 responding patients remain on treatment, including all responders treated at 24-32 mg QD RDEs
  • PDAC
    • 20 out of 23 responding patients remain on treatment, including all responders treated at 24-32 mg QD RDEs
• Safety and Tolerability: Generally well-tolerated with mostly low-grade adverse events (AEs), no dose-limiting toxicities (DLTs), low rate of dose interruptions or reductions due to treatment-related adverse events (TRAEs), and no discontinuations due to TRAEs
• Monotherapy RDE: Based on the totality of the preliminary Phase 1 dose escalation data, 24 mg and 32 mg QD were selected as the go-forward monotherapy RDEs
• Combinability: ERAS-0015 showed promising clinical potential to combine with panitumumab (anti-EGFR monoclonal antibody)
  • No DLTs observed through the 31Mar2026 DCO (N=3) with 1 unconfirmed partial response (uPR) in 1 efficacy-evaluable patient with metastatic colorectal cancer (CRC)
    
    

¹ AURORAS-1 data cutoff (DCO) 4Apr2026; JYP0015M101 data cutoff (DCO) 27Feb2026

² Pooled data from the Company's Phase 1 trial (US trial, or AURORAS-1) and Joyo's Phase 1 trial (China (CN) trial, or JYP0015M101) of ERAS-0015

³ The uORR_8wk is the ORR (confirmed and unconfirmed responses) for patients who received first dose of ERAS-0015 at least 8 weeks prior to data cutoff date (US trial) or at least one post-dose tumor assessment (CN trial)

⁴ Comparator as used in this press release, RMC-6236. Punekar et al. Journal of Thoracic Oncology 2025; data cutoff (DCO) 30Sep2024

⁵ The uORR_14wk is the ORR (confirmed and unconfirmed responses) for patients who received first dose of ERAS-0015 (US, CN) at least 14 weeks prior to data cutoff date

⁶ Wolpin et al. EORTC-NCI-AACR (ENA) 2024; DCO 23Jul2024

⁷ Revolution Medicines Press Release (10Sep2025); data cutoff (DCO) 30Jun2025

Key Upcoming and Completed Milestones

The Company initiated ERAS-0015 monotherapy expansion and combination dose escalation cohorts in the US (in Q2 2026 and Q1 2026, respectively), both ahead of previous guidance.

Upcoming milestones include:

• AURORAS-1: Phase 1 trial for ERAS-0015 (pan-RAS molecular glue) in patients with RAS-mutant solid tumors
  • Monotherapy expansion data and combination dose escalation data narrowed to an expected date of H1 2027
• BOREALIS-1: Phase 1 trial for ERAS-4001 (pan-KRAS inhibitor) in patients with KRAS-mutant solid tumors
  • Preliminary Phase 1 monotherapy data expected in the second half of 2026
  • Initiation of monotherapy expansion cohorts and combination dose escalation cohorts planned for 2027
    
    

Conference Call and Webcast Information

Erasca will hold a conference call and webcast Monday, April 27, 2026, at 4:30 pm ET. The webcast link for the conference call is here. The dial-in number is 1-877-407-3982 (U.S./Canada) or 1-201-493-6780 (international) or click the Call me™ Link. The live webcast and replay may be accessed by visiting Erasca's website at Erasca.com/events.

About ERAS-0015

ERAS-0015 is an investigational, oral, highly potent pan-RAS molecular glue designed to inhibit RAS signaling with a potential best-in-class profile. Erasca is evaluating ERAS-0015 in the AURORAS-1 Phase 1 trial in patients with RAS-mutant solid tumors. Early dose escalation data in AURORAS-1 demonstrated favorable safety and tolerability results, well-behaved, linear PK, and confirmed and unconfirmed partial responses in multiple patients across multiple tumor types with different RAS mutations, including confirmed and unconfirmed partial responses at doses as low as 8 mg once daily (QD). ERAS-0015 is also designed to prevent resistance against mutant-selective inhibitors through inhibition of RAS wildtype variants. In addition, ERAS-0015 has demonstrated favorable absorption, distribution, metabolism, and excretion (ADME) and pharmacokinetic (PK) properties in multiple animal species. 

About ERAS-4001

ERAS-4001 is an investigational, oral, highly potent, and selective pan-KRAS inhibitor with a potential first-in-class and best-in-class profile. Erasca is evaluating ERAS-4001 in the BOREALIS-1 Phase 1 trial in patients with KRAS-mutant solid tumors. ERAS-4001 demonstrated favorable preclinical in vitro potency against KRAS G12X mutations as well as KRAS wildtype amplifications, which may limit treatment resistance mediated through KRAS wildtype activation. No activity was observed for ERAS-4001 against HRAS or NRAS wildtype proteins in preclinical studies, which may enable a better therapeutic window compared to pan-RAS inhibitors. ERAS-4001 showed potent activity against both GTP-bound (active state) and GDP-bound (inactive state) KRAS with single digit nanomolar IC50s. In vivo, ERAS-4001 induced tumor regression in multiple KRAS-mutant models. In preclinical studies, ERAS-4001 showed encouraging ADME and PK properties. 

About Erasca

At Erasca, our name is our mission: To erase cancer. We are a clinical-stage precision oncology company singularly focused on discovering, developing, and commercializing therapies for patients with RAS/MAPK pathway-driven cancers. Our company was co-founded by leading pioneers in precision oncology and RAS targeting to create novel therapies and combination regimens designed to comprehensively shut down the RAS/MAPK pathway for the treatment of patients with cancer. We believe our team's capabilities and experience, further guided by our scientific advisory board which includes the world's leading experts in the RAS/MAPK pathway, uniquely position us to achieve our bold mission of erasing cancer.

Cautionary Note Regarding Forward-Looking Statements

Erasca cautions you that statements contained in this press release regarding matters that are not historical facts are forward-looking statements. The forward-looking statements are based on our current beliefs and expectations and include, but are not limited to: our expectations regarding the potential therapeutic benefits of our product candidates, including ERAS-0015 and ERAS-4001, and the planned advancement of our development pipeline, including the anticipated timing of data readouts for the AURORAS-1 and BOREALIS-1 trials, characterizations of the clinical profile of our product candidates and any comparisons against other products or product candidates in development, the potential for ERAS-0015 to be best-in-class or serve as backbone therapy for future combination therapies, and the potential for ERAS-4001 to be first-in-class or best-in-class. Actual results may differ from those set forth in this press release due to the risks and uncertainties inherent in our business, including, without limitation: the timing of our clinical data readouts, including for the AURORAS-1 and BOREALIS-1 trials may be delayed; our product candidates, including ERAS-0015 and ERAS-4001, may not demonstrate therapeutic benefits that we expect; this press release includes clinical data generated by our third-party licensor, and such data are presented as received and have not been independently verified by us; topline and preliminary results of a clinical trial are not necessarily indicative of final results and one or more of the clinical outcomes may materially change as patient enrollment continues, following more comprehensive reviews of the data and as more patient data becomes available, including the risk that an unconfirmed partial response to treatment may not ultimately result in a confirmed partial response to treatment after follow-up evaluations; our observations, including those regarding the first dosage level at which a clinical response is detected and the efficacy and safety of ERAS-0015 compared to other products and product candidates, are based on data generated within separate, individual clinical trials with different designs, patient characteristics and other factors and are not based on any head-to-head clinical studies, and caution should be exercised in drawing any conclusions from a comparison of the data across studies as cross-study comparisons are inherently limited and such data may not be directly comparable; differences exist between trial designs, patient characteristics and other factors for the AURORAS-1 and JYP0015M101 clinical trials, and caution should be exercised in drawing any conclusions from such data across separate studies as such pooling and comparative data is inherently limited and such data may not be directly comparable; any forward-looking statements regarding dose-response relationships reflect current expectations and/or assumptions are subject to risks and uncertainties that could cause actual results to differ materially; our approach to the discovery and development of product candidates based on our singular focus on shutting down the RAS/MAPK pathway, a novel and unproven approach; results from preclinical studies not necessarily being predictive of future results; our assumptions around which programs may have a higher probability of success may not be accurate, and we may expend our limited resources to pursue a particular product candidate and/or indication and fail to capitalize on product candidates or indications with greater development or commercial potential; potential delays in the commencement, enrollment, data readout, and completion of clinical trials and preclinical studies; our dependence on third parties in connection with manufacturing, research, and preclinical and clinical testing; unexpected adverse side effects or inadequate efficacy of our product candidates that may limit their development, regulatory approval, and/or commercialization, or may result in recalls or product liability claims; unfavorable results from preclinical studies or clinical trials; the inability to realize any benefits from our current licenses, acquisitions, and collaborations, and any future licenses, acquisitions, or collaborations, and our ability to fulfill our obligations under such arrangements; regulatory developments in the United States and foreign countries; our ability to obtain and maintain intellectual property protection for our product candidates and maintain our rights under intellectual property licenses, including our ability to successfully defend against allegations raised by, or any future litigation initiated by, Revolution Medicines (RevMed) that ERAS-0015 infringes patents held by RevMed or was derived from RevMed trade secrets; the sufficiency of our cash, cash equivalents, and marketable securities to fund operations; we may use our capital resources sooner than we expect; and other risks described in our prior filings with the Securities and Exchange Commission (SEC), including under the heading "Risk Factors" in our annual report on Form 10-K for the year ended December 31, 2025, and any subsequent filings with the SEC. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and we undertake no obligation to update such statements to reflect events that occur or circumstances that exist after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

Contact:

Joyce Allaire

LifeSci Advisors, LLC

jallaire@lifesciadvisors.com

Source: Erasca, Inc.