Erasca Presents Promising Initial Phase 1b Dose Escalation Data from FLAGSHP-1 for ERAS-601 Plus Cetuximab in Patients with Advanced Solid Tumors at the 2023 AACR Annual Meeting

ERAS-601, a potential best-in-class SHP2 inhibitor, blocks oncogenic signal transduction to delay onset of therapeutic resistance

Combination was well-tolerated; supports ‘three weeks on, one week off’ dosing of ERAS-601

Dose expansion data in HPV-negative HNSCC expected in H1 2024

SAN DIEGO, April 18, 2023 (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 presented promising initial Phase 1b dose escalation data from FLAGSHP-1 for ERAS-601 in combination with cetuximab (ERBITUX^®) in patients with advanced solid tumors as part of a poster presentation at the American Association for Cancer Research (AACR) Annual Meeting in Orlando, Florida. ERAS-601 is a potent, selective, oral small molecule SHP2 inhibitor with best-in-class potential. The poster is available online at Erasca.com/science/presentations.

“We are pleased with the outcome of the FLAGSHP-1 dose escalation evaluation of ERAS-601 plus cetuximab, which supports ERAS-601 being a backbone for combination therapy. The combination with cetuximab was well-tolerated with favorable pharmacokinetics and no apparent drug-drug interactions. In addition, to our knowledge, this is the first clinical evaluation of a SHP2 inhibitor and EGFR monoclonal antibody, the combination of which effectively inhibits oncogenic receptor tyrosine kinase signaling,” said Jonathan E. Lim, M.D., Erasca’s chairman, CEO, and co-founder. “That we saw predominantly low-grade adverse events (AEs) reinforces our hypothesis that a ‘three weeks on, one week off’ dosing regimen for ERAS-601 in combination may lead to fewer and milder AEs.”

Dr. Lim continued, “The stable disease observed during this initial all comers dose escalation evaluation in heavily pretreated patients supports our plan to explore preliminary efficacy in human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC), an indication of high unmet need, with the now identified maximum tolerated dose (MTD) for the combination. We believe this patient population may be particularly responsive to this combination based on encouraging synergistic activity observed in preclinical studies. We expect to share initial Phase 1b dose expansion combination data in the first half of 2024.”

Poster Presentation Highlights
Preliminary dose escalation results of ERAS-601 in combination with cetuximab in FLAGSHP-1: A Phase I study of ERAS-601, a potent and selective SHP2 inhibitor, in patients with previously treated advanced or metastatic solid tumors
ERAS-601 in combination with cetuximab inhibits RAS/MAPK signaling at multiple nodes which is predicted to limit the development of treatment resistance and offer more robust synergistic anti-tumor activity over monotherapy alone. Characterization of the safety profile, determination of the maximum tolerated dose (MTD)/recommended dose (RD), and characterization of the pharmacokinetic profile of ERAS-601 in combination with cetuximab was evaluated as part of the Phase 1/1b FLAGSHP-1 trial in patients with advanced or metastatic solid tumors.

• ERAS-601 in combination with cetuximab shows promising preliminary safety and tolerability with reversible and manageable treatment-related adverse events (TRAEs)
• Only grade 1 or 2 TRAEs occurred at or below the combination MTD for ERAS-601
• ERAS-601 MTD was determined to be 40 mg BID 3/1 (three-week dosing followed by a one-week break) in combination with cetuximab (500 mg/m²) administered every 2 weeks
• Initial Phase 1b dose expansion data in HPV-negative HNSCC tumors (NCT04670679) is expected in H1 2024

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 cancer. We have assembled what we believe to be the deepest RAS/MAPK pathway-focused pipeline in the industry. 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 and safety profile of our product candidates, including ERAS-601; and the planned advancement of our development pipeline, including the anticipated timing of data readouts for the FLAGSHP-1 trial, and other upcoming development milestones. 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: 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; potential delays in the commencement, enrollment, 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; results from preclinical studies or early clinical trials not necessarily being predictive of future results; the inability to realize any benefits from our current licenses, collaborations, and acquisitions and any future licenses, collaborations, and acquisitions, and our ability to fulfill our obligations under such arrangements; regulatory developments in the United States and foreign countries; our dependence on third parties in connection with our existing collaboration and supply agreements and the inability realize any benefits from such agreements; our ability to obtain and maintain intellectual property protection for our product candidates and maintain our rights under intellectual property licenses; our ability to fund our operating plans with our current cash, cash equivalents, and marketable securities; our ability to maintain undisrupted business operations due to the COVID-19 pandemic and global geopolitical events, such as the ongoing conflict between Russia and Ukraine; unstable market and economic conditions and adverse developments with respect to financial institutions and associated liquidity risk may adversely affect our business, financial condition and stock price, and the broader economy and biotechnology industry; and other risks described in our prior filings with the Securities and Exchange Commission (SEC), including under the heading “Risk Factors” in our quarterly report on Form 10-K for the year ended December 31, 2022, 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.

ERBITUX^® is a registered trademark owned or licensed by Eli Lilly and Company, its subsidiaries, or affiliates.

Contact:
Joyce Allaire
LifeSci Advisors, LLC
jallaire@lifesciadvisors.com