Company: ERAS
Filing Date: 2025-08-12
Form Type: S-3
Source: 0001193125-25-179038
Chunk: 46

Company: Erasca, Inc.
Filing Date: 2025-08-12
Form: S-3
Chunk 46
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 shares of our common stock to be outstanding immediately after this offering is based on 283,650,139 shares of our common stock outstanding as of June 30, 2025. The number of shares outstanding as of June 30, 2025 excludes:

| • |     | 47,790,988 shares of common stock issuable upon the exercise of options outstanding as of June 30, 2025, at 
 a weighted average exercise price of $3.25 per share; and                                                   |

| • |     | 17,516,848 shares of common stock reserved for future issuance under our 2021 Incentive Award Plan and our 2021 
 Employee Stock Purchase Plan as of June 30, 2025.                                                               |

S-5

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully review the risks and uncertainties described below and under the section titled “Risk Factors” in our most recent Annual Report on Form 10-Kand any subsequent Quarterly Reports on Form 10-Qor Current Reports on Form 8-Kwe file after the date of this prospectus, and all other information contained or incorporated by reference into this prospectus, as updated by our subsequent filings under the Exchange Act, before acquiring any of such securities. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities.

Risks Relating to this Offering

If you purchase shares of our common stock sold in this offering, you will experience immediate and substantial dilution in the net tangible book value of your shares. In addition, we may issue additional equity or convertible debt securities in the future, which may result in additional dilution to investors.

The price per share of our common stock being offered may be higher than the net tangible book value per share of our outstanding common stock prior to this
offering. Assuming that an aggregate of 142,857,142 shares of our common stock are sold at a price of $1.40 per share, the last reported sale price of our common stock on the Nasdaq Global Select Market on August 8, 2025, for aggregate gross
proceeds of approximately $200 million, and after deducting commissions and estimated offering expenses payable by us, new investors in this offering would incur immediate dilution of $0.07 per share. For a more detailed discussion of the
foregoing, see the section entitled “Dilution” below. To the extent outstanding stock