C4 Therapeutics, Inc.

Previous wording

We are a clinical-stage biopharmaceutical company with limited operating history. Our net loss was $52.3 million and $46.1 million for six months ended June 30, 2025 and 2024, respectively. As of June 30, 2025, we had an accumulated deficit of $686.0 million. To date, we have not generated any revenue from product sales and have financed our operations primarily through sales of our equity interests, including public offerings of our common stock, proceeds from our collaborations, share issuances and debt financing. We are still in the early stages of development of our product candidates. As a result, we expect that it will be several years, if ever, before we have a product candidate ready for regulatory approval and commercialization. We may never succeed in these activities and, even if we do, may never generate revenues that are significant enough to achieve profitability. To become and remain profitable, we must succeed in developing, obtaining marketing approval for, and commercializing products that generate significant revenue. This will require us to be successful in a range of challenging activities, including, without limitation, successfully completing preclinical studies and clinical trials of our product candidates, discovering additional product candidates, establishing arrangements with third parties for the conduct of our clinical trials, procuring clinical and commercial-scale manufacturing, obtaining marketing approval for our product candidates, manufacturing, marketing and selling any products for which we may obtain marketing approval, identifying collaborators to develop product candidates we identify or additional uses of existing product candidates, and successfully completing development of product candidates for our collaboration partners.

Current wording

We are a clinical-stage biopharmaceutical company with limited operating history. Our net loss was $84.5 million and $70.7 million for nine months ended September 30, 2025 and 2024, respectively. As of September 30, 2025, we had an accumulated deficit of $718.2 million. To date, we have not generated any revenue from product sales and have financed our operations primarily through sales of our equity interests, including public offerings of our common stock, proceeds from our collaborations, share issuances and debt financing. We are still in the early stages of development of our product candidates. As a result, we expect that it will be several years, if ever, before we have a product candidate ready for regulatory approval and commercialization. We may never succeed in these activities and, even if we do, may never generate revenues that are significant enough to achieve profitability. To become and remain profitable, we must succeed in developing, obtaining marketing approval for, and commercializing products that generate significant revenue. This will require us to be successful in a range of challenging activities, including, without limitation, successfully completing preclinical studies and clinical trials of our product candidates, discovering additional product candidates, establishing arrangements with third parties for the conduct of our clinical trials, procuring clinical and commercial-scale manufacturing, obtaining marketing approval for our product candidates, manufacturing, marketing and selling any products for which we may obtain marketing approval, identifying collaborators to develop product candidates we identify or additional uses of existing product candidates, and successfully completing development of product candidates for our collaboration partners.

Previous wording

We had cash, cash equivalents, and marketable securities of approximately $223.0 million as of June 30, 2025. We believe that these funds will be sufficient to fund our planned operating expenses to mid-2027. We have based this estimate on assumptions that may prove to be wrong, and we could deplete our current capital resources sooner than we currently expect. Our future capital requirements will depend on many factors, including:

Current wording

We had cash, cash equivalents, and marketable securities of approximately $199.8 million as of September 30, 2025. In October 2025, we sold 21,895,000 shares, or the Shares, of our common stock and, in lieu of common stock to certain investors, pre-funded warrants to purchase 28,713,500 shares of common stock, or the Pre-Funded Warrants, as well as accompanying Class A warrants to purchase an aggregate of 50,608,500 shares of our common stock (or, for those investors who so choose, pre-funded warrants), or the Class A Warrants, and Class B warrants to purchase an aggregate of 50,608,500 shares of our common stock (or, for those investors who so choose, pre-funded warrants), of the Class B Warrants, in an underwritten offering, or the 2025 Offering. We received net proceeds of approximately $117.0 million, after deducting the underwriting discount and commissions and estimated offering expenses. We believe that together these funds will be sufficient to fund our planned operating expenses to end of 2028. We have based this estimate on assumptions that may prove to be wrong, and we could deplete our current capital resources sooner than we currently expect. We cannot predict whether any pre-funded warrants, Class A Warrants or Class B Warrants issued in the 2025 Offering will be exercised and, therefore, have not included any anticipated proceeds from the potential exercise of these warrants in our estimate of our cash runway.

Previous wording

While we have ongoing clinical trials, at this time, we have not yet completed a late stage or registrational clinical trial of any product candidate. As a result, we are only starting to assess the safety of our lead product candidates in patients, and we have not yet assessed the safety of any of our other earlier-stage product candidates in humans. Although some of our earlier-stage product candidates have produced observable results in animal studies, there is a limited safety data set for their effects in animals. In addition, these product candidates may not demonstrate the same chemical and pharmacological properties in humans and may interact with human biological systems in unforeseen, ineffective or harmful ways. As a result, there could be adverse effects from treatment with any of our current or future product candidates that we cannot predict at this time.

Current wording

While we have ongoing clinical trials, at this time, we have not yet completed a late stage or registrational clinical trial of any product candidate. As a result, we are only starting to assess the safety of our lead product candidate in patients, and we have not yet assessed the safety of any of our other earlier-stage product candidates in humans. Although some of our earlier-stage product candidates have produced observable results in animal studies, there is a limited safety data set for their effects in animals. In addition, these product candidates may not demonstrate the same chemical and pharmacological properties in humans and may interact with human biological systems in unforeseen, ineffective or harmful ways. As a result, there could be adverse effects from treatment with any of our current or future product candidates that we cannot predict at this time.

Previous wording

Further, large-scale clinical trials would require significant additional financial and management resources and reliance on third-party clinical investigators, contract research organizations, or CROs, and consultants. Relying on third-party clinical investigators, CROs and consultants may cause us to encounter delays that are outside of our control and, for each of the product candidates that is currently in clinical development, we have engaged a CRO to lead our first-in-human Phase 1/2 clinical trials. Relying on third parties in the conduct of our preclinical studies or clinical trials exposes us to a risk that they may not adequately adhere to study or trial protocols or comply with good laboratory practice or good clinical practice, or GCP, as required for any studies or trials we plan to submit to a regulatory authority. We may also be unable to identify and contract with sufficient investigators, CROs, and consultants on a timely basis or at all, and we may also determine and have in the past determined after a clinical trial has commenced that a change in CRO is warranted. There can be no assurance that we will be able to negotiate and enter into appropriate contractual arrangements with our current or potential future CROs, if and when necessary for our other product candidates, on terms that are acceptable to us on a timely basis or at all.

Current wording

Further, large-scale clinical trials would require significant additional financial and management resources and reliance on third-party clinical investigators, contract research organizations, or CROs, and consultants. Relying on third-party clinical investigators, CROs and consultants may cause us to encounter delays that are outside of our control and, for each of the product candidates that is currently in clinical development, we have engaged CROs to lead our first-in-human Phase 1/2 clinical trials. Relying on third parties in the conduct of our preclinical studies or clinical trials exposes us to a risk that they may not adequately adhere to study or trial protocols or comply with good laboratory practice or good clinical practice, or

Previous wording

Many of our current or potential competitors, either alone or with their collaboration partners, have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals, and marketing approved products than we do. These competitors also compete with us in recruiting and retaining qualified scientific and management personnel and establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our product candidates. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors, the scale of which could be difficult to compete against. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than any product candidate that we may develop. Our competitors also may obtain FDA or other regulatory approval for their product candidates more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of generic products. There are generic products currently on the market for certain of the indications that we are pursuing, and additional products are expected to become available on a generic basis over the coming years. If our product candidates are approved, we expect that they will be priced at a significant premium over competitive generic products.

Current wording

Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than any product candidate that we may develop. Our competitors also may obtain FDA or other regulatory approval for their product candidates more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of generic products. There are generic products currently on the market for certain of the indications that we are pursuing, and additional products are expected to become available on a generic basis over the coming years. If our product candidates are approved, we expect that they will be priced at a significant premium over competitive generic products.

Previous wording

We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We rely on and expect to continue to rely on CMOs for both drug substance and finished drug product. This reliance on third parties may increase the risk that we will not have sufficient quantities of our product candidates or products or that we will not have the quantities we desire or require at an acceptable cost or quality, which could delay, prevent, or impair our development or commercialization efforts, including where a pre-approval inspection or an inspection of manufacturing sites is required and FDA is unable to complete those required inspections during the review period for any reason.

Current wording

We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We rely on and expect to continue to rely on contract manufacturing organizations, or CMOs, for both drug substance and finished drug product. This reliance on third parties may increase the risk that we will not have sufficient quantities of our product candidates or products or that we will not have the quantities we desire or require at an acceptable cost or quality, which could delay, prevent, or impair our development or commercialization efforts, including where a pre-approval inspection or an inspection of manufacturing sites is required and FDA is unable to complete those required inspections during the review period for any reason.

Previous wording

Any performance failure or delay in performance on the part of our existing or future manufacturers could delay clinical development or marketing authorization. While our CMOs have experienced performance issues in the past that have not ultimately delayed our clinical development efforts, in the future, we could experience a manufacturing issue that would have a material impact on development of our product candidates and the occurrence of an event of this nature would largely be outside of our control. We do not currently have arrangements in place for redundant supply or a second source for drug substance or drug product. If our current CMOs cannot perform as agreed, we may be required to replace them. While we have identified several potential alternative vendors who could manufacture some or all of our product candidates, switching vendors could result in significant additional costs and delays to our operations as we select and qualify a replacement manufacturer, we may be constrained in the vendors we can select, particularly for compounds that have high OEB designations, or we may not be able to reach agreement with an alternative manufacturer on acceptable terms.

Current wording

Any performance failure or delay in performance on the part of our existing or future manufacturers could delay clinical development or marketing authorization. While our CMOs have experienced performance issues in the past that have not ultimately delayed our clinical development efforts, in the future, we could experience a manufacturing issue that would have a material impact on development of our product candidates and the occurrence of an event of this nature would largely be outside of our control. We do not currently have arrangements in place for redundant supply or a second source for drug substance or drug product. If our current CMOs cannot perform as agreed, we may be required to replace them. While we have identified several potential alternative vendors who could manufacture some or all of our product candidates, switching vendors could result in significant additional costs and delays to our operations as we select and qualify a replacement manufacturer, we may be constrained in the vendors we can select, particularly for compounds that have high OEB designations, or we may not be able to reach agreement with an alternative manufacturer on acceptable terms. Similarly, our clinical supply partners, such as Pfizer in the case of elranatamab, may rely on a variety of third parties in connection with the manufacturing of their products. Any performance failure or delay on the part of Pfizer or any of these third parties that delays, halts, or otherwise materially impacts the availability of supply of these combination therapies could have a material impact on development of our product candidates.

Previous wording

We have three ongoing collaborations involving our research programs:

Current wording

We have the following ongoing collaborations involving our research programs:

Previous wording

•a collaboration agreement with Roche that we entered into in December 2015, which we amended and restated in December 2018 and further amended periodically thereafter, with collaboration activities ongoing as to two targets;

Current wording

•a collaboration agreement with Roche that we entered into in December 2015, which we amended and restated in December 2018 and further amended periodically thereafter, with collaboration activities ongoing as to two targets; and

Previous wording

Because our clinical candidates are pharmaceutical molecules that will be reviewed by the Center for Drug Evaluation and Research of the FDA, after commercialization they will be subject in the United States to the patent litigation process of the Hatch-Waxman Act, as amended to date, which allows a generic company to submit an Abbreviated New Drug Application, or ANDA, to the FDA to obtain approval to sell a generic version of our drug using bioequivalence data only. Under the Hatch-Waxman Act, we will list patents that cover our drug products or their respective methods of use in the

Current wording

Because our clinical candidates are pharmaceutical molecules that will be reviewed by the Center for Drug Evaluation and Research of the FDA, after commercialization they will be subject in the United States to the patent litigation process of the Hatch-Waxman Act, as amended to date, which allows a generic company to submit an Abbreviated New Drug Application, or ANDA, to the FDA to obtain approval to sell a generic version of our drug using bioequivalence data only. Under the Hatch-Waxman Act, we will list patents that cover our drug products or their respective methods of use in the FDA’s compendium of “Approved Drug Products with Therapeutic Equivalence Evaluation,” sometimes referred to as the Orange Book.

Previous wording

Any regulatory approvals that we receive for our product candidates may be subject to limitations on the approved indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for potentially costly post-marketing testing, including Phase 4 clinical trials and surveillance to monitor the safety and efficacy of the product candidate. The FDA may also require a REMS program as a condition of approval of our product candidates, which could entail requirements for long-term patient follow-up, a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries, and other risk minimization tools. Comparable foreign regulatory authorities may also have programs similar to REMS. In addition, if the FDA or a comparable foreign regulatory authority approves our product candidates, we will have to comply with requirements including submissions of safety and other post-marketing information and reports and registration.

Current wording

Any regulatory approvals that we receive for our product candidates may be subject to limitations on the approved indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for potentially costly post-marketing testing, including Phase 4 clinical trials and surveillance to monitor the safety and efficacy of the product candidate. The FDA may also require a REMS program as a condition of approval of our product candidates, which could entail requirements for long-term patient follow-up, a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries, and other risk minimization tools. Comparable foreign regulatory authorities may also have programs similar to REMS. In addition, if the

Previous wording

The global data protection landscape is rapidly evolving, and we may be or become subject to or affected by numerous federal, state, and foreign laws and regulations, as well as regulatory guidance, governing the collection, use, disclosure, transfer, security and processing of personal data, such as information that we collect about participants and healthcare providers in connection with clinical trials. Implementation standards and enforcement practices are likely to remain uncertain for the foreseeable future, which may create uncertainty in our business, affect our or our service providers’

Current wording

The global data protection landscape is rapidly evolving, and we may be or become subject to or affected by numerous federal, state, and foreign laws and regulations, as well as regulatory guidance, governing the collection, use, disclosure, transfer, security and processing of personal data, such as information that we collect about participants and healthcare providers in connection with clinical trials. Implementation standards and enforcement practices are likely to remain uncertain for the foreseeable future, which may create uncertainty in our business, affect our or our service providers’ ability to operate in certain jurisdictions or to collect, store, transfer use and share personal data, result in liability or impose additional compliance or other costs on us. Any failure or perceived failure by us to comply with federal, state or foreign laws or self-regulatory standards could result in negative publicity, diversion of management time and effort and proceedings against us by governmental entities or others.

Previous wording

Further, certain health privacy laws, data breach notification laws, consumer protection laws and genetic testing laws may apply directly to our operations and/or those of our collaborators and may impose restrictions on our collection, use and dissemination of individuals’ health information. Patients about whom we or our collaborators may obtain health information, as well as the providers who may share this information with us, may have statutory or contractual rights that limit our ability to use and disclose the information. We may be required to expend significant capital and other resources to ensure ongoing compliance with applicable privacy and data security laws. Claims that we have violated individuals’

Current wording

Further, certain health privacy laws, data breach notification laws, consumer protection laws and genetic testing laws may apply directly to our operations and/or those of our collaborators and may impose restrictions on our collection, use and dissemination of individuals’ health information. Patients about whom we or our collaborators may obtain health information, as well as the providers who may share this information with us, may have statutory or contractual rights that limit our ability to use and disclose the information. We may be required to expend significant capital and other resources to ensure ongoing compliance with applicable privacy and data security laws. Claims that we have violated individuals’ privacy rights or breached our contractual obligations, even if we are not found liable, could be expensive and time-consuming to defend and could result in adverse publicity that could harm our business.

Previous wording

We may choose to raise additional capital in the future through the sale of shares or other securities convertible into shares, depending on market conditions, strategic considerations, and operational requirements. To the extent we raise additional capital in this manner, our stockholders will be diluted. Future issuances of our common stock or other equity securities, or the perception that sales of this nature may occur, could adversely affect the trading price of our common stock, and impair our ability to raise capital through future offerings of shares or equity securities. No prediction can be made as to the effect, if any, that future sales of common stock or the availability of common stock for future sales will have on the trading price of our common stock.

Current wording

Future issuances of our common stock or other equity securities, or the perception that sales of this nature may occur, could adversely affect the trading price of our common stock, and impair our ability to raise capital through future offerings of shares or equity securities. No prediction can be made as to the effect, if any, that future sales of common stock or the availability of common stock for future sales will have on the trading price of our common stock.