C4 Therapeutics Highlights Recent Achievement in Biogen Collaboration

C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation science, today announced that its partner Biogen has had its investigational new drug (IND) application for BIIB142 accepted by the U.S. Food and Drug Administration (FDA). BIIB142 is a degrader of IRAK4 that Biogen intends to explore for therapeutic use in patients with autoimmune diseases.

"We are thrilled to see Biogen quickly advance the IRAK4 degrader that resulted from our collaboration toward the clinic in the hopes this molecule may bring a new treatment option to patients with autoimmune disease," said Paige Mahaney, Ph.D., chief scientific officer of C4 Therapeutics. "Our long-standing collaboration with Biogen helped C4T build and deepen capabilities across our platform as we worked together to develop degraders for a broad range of target classes and therapeutic areas to reach a sizeable number of patients with unmet needs. We look forward to Biogen's continued progress with BIIB142, as well as the second development candidate delivered under our collaboration."

"Our collaboration with C4 Therapeutics has been both powerful and deeply productive, pairing C4T's expertise in targeted protein degradation with Biogen's scientific leadership and drug development capabilities," said Jane Grogan, Ph.D., head of research at Biogen. "I'm proud that we have advanced this program based on a cutting-edge modality for a disease with high unmet need, and we see great promise in continuing to pioneer these types of investigational approaches."

Under the terms of the strategic collaboration established in 2018, C4T provided expertise and research services in targeted protein degradation and Biogen provided scientific and drug development capabilities. C4T delivered two development candidates to Biogen under this collaboration. Biogen is responsible for all future clinical development and commercialization for these development candidates. C4T is entitled to receive a $2 million milestone payment upon Biogen dosing patients in the BIIB142 clinical trial.

About C4 Therapeutics
C4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients' lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO ^® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T's degrader medicines are designed to harness the body's natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com .

Forward-Looking Statements
This press release contains "forward-looking statements" of C4 Therapeutics, Inc. within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding the design and potential efficacy of our therapeutic approaches; and the potential timing of clinical development activities or the receipt of related milestone payments. Any forward-looking statements in this press release are based on management's current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of clinical studies by Biogen; the risk that this product candidate may not be successfully developed and commercialized; and the risk that we will receive future milestone or royalty payments related to the development of this product candidate. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled "Risk Factors" in C4 Therapeutics' most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law.

Contacts:
Investors:
Courtney Solberg
Associate Director, Investor Relations
CSolberg@c4therapeutics.com

Media:
Loraine Spreen
Senior Director, Corporate Communications & Patient Advocacy
LSpreen@c4therapeutics.com