C4 Therapeutics Inc美股招股说明书(2025-10-16版)

21,895,000 Shares of Common StockPre-fundedWarrants to Purchase up to 28,713,500 Shares of Common StockClass A Warrants to Purchase up to 50,608,500 Shares of Common Stock(orPre-FundedWarrants)Class B Warrants to Purchase up to 50,608,500 Shares of Common Stock(orPre-FundedWarrants) We are offering 21,895,000 shares of our common stock and, in lieu of common stock to certain investors that so choose,pre-fundedwarrants topurchase 28,713,500 shares of common stock, as well as accompanying ClassA warrants, or ClassA Warrants, to purchase an aggregate of 50,608,500shares of our common stock (or, for those investors who so choose,pre-fundedwarrants) and ClassB warrants, or ClassB Warrants, to purchase anaggregate of 50,608,500 shares of our common stock (or, for those investors who so choose,pre-fundedwarrants). The purchase price of eachpre-fundedwarrant equals the price per share at which shares of common stock and the accompanying ClassA and ClassB Warrants are being sold tothe public in this offering, minus the $0.0001 per share exercise price of each suchpre-fundedwarrant. This prospectus supplement also relates to theoffering of the shares of common stock issuable upon exercise of suchpre-fundedwarrants and ClassA and ClassB Warrants. The common stock andpre-fundedwarrants will be sold in combination, with each share of common stock orpre-fundedwarrant that we sell in this offering being accompaniedby a Class A Warrant to purchase one share of common stock orpre-fundedwarrant and a ClassB Warrant to purchase one share of common stock orpre-fundedwarrant. The shares of our common stock (orpre-fundedwarrants) and ClassA and ClassB Warrants are immediately separable and will be issued separately,but can only be purchased together in the offering. The ClassA Warrants have an exercise price of $2.22 per share of common stock, or $2.2199 perpre-fundedwarrant, are exercisable at any time after the date of issuance and will expire on the earlier of (i)30 calendar days following the public releaseofnine-monthmedianfollow-updata from any expansion cohort in our planned Phase1b study of cemsidomide with elranatamab and (ii)the fifthanniversary of the date of issuance. The ClassB Warrants have an exercise price of $2.22 per share of common stock, or $2.2199 perpre-fundedwarrant, are exercisable any time after the date of issuance and will expire on the fifth anniversary of the date of issuance; provided that we may requirethe mandatory exercise of the ClassB Warrants, in whole or in part, on or after thesix-monthanniversary of the date of issuance and so long as the pershare closing price of our common stock on The Nasdaq Global Select Market on each of the ten consecutive trading days prior to the date of our noticeof mandatory exercise is above $6.66, subject to certain adjustments. Thepre-fundedwarrants are immediately exercisable, subject to the limitationsdescribed in the section “Description of Securities We Are Offering.” We refer to the common stock, thepre-fundedwarrants and the respective accompanying ClassA Warrants and ClassB Warrants issued in this offering,collectively, as the securities. We refer to the ClassA Warrants and ClassB Warrants accompanying the common stock andpre-fundedwarrants as theClassA and ClassB Warrants. Our common stock is listed on The Nasdaq Global Select Market under the symbol “CCCC.” On October15, 2025, the closing price of our common stock,as reported on The Nasdaq Global Select Market, was $2.22 per share. Investing in our common stock involves a high degree of risk. You should review carefully the risks and uncertainties referenced under theheading “Risk Factors” onpageS-8of this prospectus supplement and page2 of the accompanying prospectus and in the documents that areincorporated by reference herein and therein. You should read the entire prospectus supplement and the accompanying prospectus, includingany information incorporated by reference herein or therein, carefully before you make your investment decision. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities ordetermined if this prospectus supplement and the accompanying prospectus is truthful or complete. Any representation to the contrary is acriminal offense. We are a “smaller reporting company” under the federal securities laws and, as such, are subject to reduced public company reporting requirements. See“Prospectus Supplement Summary—Implications of Being a Smaller Reporting Company.” Delivery of the shares of common stock andpre-fundedwarrants (and the respective accompanying ClassA and ClassB Warrants) is expected to bemade on or about October17, 2025. TDCowen Table of Contents TABLE OF CONTENTS Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This document is part of the registration statement that we filed with the Securities and Exchange Commission, or the SEC, using a “shelf”registration process, and consists of