INTENSITY THERAPEUTICS, INC.

FOR THE SPECIAL MEETING OF STOCKHOLDERS

TO BE HELD ON OCTOBER 22, 2025

This proxy statement (the “Proxy Statement”) is furnished to stockholders of Intensity Therapeutics, Inc., a Delaware corporation (the “Company,” “we,” “us,” or “our”), in connection with the solicitation of proxies by our board of directors for use at a special meeting of stockholders to be held on October 22, 2025, and at any adjournment or postponement thereof (our “Special Meeting”). Our Special Meeting will be held at 10:30a.m. Eastern time via a live audio webcast at www.virtualshareholdermeeting.com/INTS2025SM.

On or about September 9, 2025, we will commence mailing of the proxy materials which are also available at www.proxyvote.com. The proxy materials are being sent to stockholders who owned our common stock at the close of business on August 29, 2025, the record date for the Special Meeting (the “Record Date”). This Proxy Statement contains important information for you to consider when deciding how to vote on the matters brought before the meeting. Please read it carefully.

Why am I receiving these materials?

We sent you this Proxy Statement because our board of directors is soliciting your proxy to vote at our Special Meeting. This Proxy Statement summarizes the information you need to vote at our Special Meeting. You do not need to attend our Special Meeting to vote your shares.

What proposals will be voted on at the Special Meeting?

Stockholders will vote on two proposals at the Special Meeting:

1. The approval of an amendment to our Amended and Restated Certificate of Incorporation, as amended (the “Amended and Restated Certificate of Incorporation”), to effect a reverse stock split of our common stock by a ratio of not less than one-for-five and not more than one-for-thirty (the “Reverse Stock Split”), with the exact ratio to be set within this range by our board of directors in its sole discretion (without reducing the authorized number of shares of our common stock) and with our board of directors able to elect to abandon such proposed amendment and not effect the Reverse Stock Split authorized by our stockholders in its sole discretion (the “Amendment Proposal”); and

2. The approval of the adjournment of the Special Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies in the event there are not sufficient votes in favor of the Amendment Proposal (the “Adjournment Proposal”).

Our board of directors knows of no other matters that will be presented for consideration at the Special Meeting. If any other matters are properly brought before the Special Meeting, it is the intention of the persons named in the accompanying proxy to vote on those matters in accordance with their best judgment.

How do I attend the Special Meeting?

To be admitted to the Special Meeting, you will need to visit www.virtualshareholdermeeting.com/INTS2025SM and enter the 16-digit control number found next to the label “Control Number” on your proxy card or voting instruction form. If you are a beneficial stockholder, you should contact the bank, broker, or other institution where you hold your account well in advance of the Special Meeting if you have questions about obtaining your control number/proxy to vote.

WHETHER OR NOT YOU PARTICIPATE IN THE SPECIAL MEETING, IT IS

IMPORTANT THAT YOU VOTE YOUR SHARES

Can I ask questions during the Special Meeting?

Stockholders will have the ability to submit questions during the Special Meeting via the Special Meeting website at www.virtualshareholdermeeting.com/INTS2025SM. Questions may be submitted online shortly prior to, and during, the Special Meeting by logging in with the 16-digit control number at www.virtualshareholdermeeting.com/INTS2025SM. We will answer questions during the Special Meeting that are pertinent to the proposals presented at the Special Meeting, subject to time constraints. If we receive substantially similar written questions, we plan to group such questions together and provide a single response to avoid repetition and allow time for additional question topics. Additional information regarding the rules and procedures for participating in the virtual Special Meeting will be provided in our rules of conduct for the Special Meeting, which stockholders can view during the Special Meeting at the Special Meeting website.

What happens if there are technical difficulties at the Special Meeting?

We will have technicians ready to assist you with any technical difficulties you may have when accessing the virtual Special Meeting, voting at the Special Meeting, or submitting questions at the Special Meeting. If you encounter any difficulties accessing the virtual Special Meeting during the check-in or meeting time, please call the technical support number on the log in screen at www.virtualshareholdermeeting.com/INTS2025SM.

How does the board of directors recommend that stockholders vote on the proposals?

Our board of directors recommends that stockholders vote “FOR” the Amendment Proposal and “FOR” the Adjournment Proposal.

Who is entitled to vote?

As of the Record Date, there were 49,055,462 shares of our common stock and no shares of our preferred stock outstanding and entitled to vote at the Special Meeting. Holders of record of our common stock as of the Record Date will be entitled to vote on the Amendment Proposal and the Adjournment Proposal at our Special Meeting or any adjournment or postponement thereof.

A list of stockholders entitled to vote at the Special Meeting will be available for examination during normal business hours for ten days before the Special Meeting at our address above.

If on the Record Date your shares were registered directly in your name with our transfer agent, Continental Stock Transfer & Trust Company, then you are a stockholder of record. As a stockholder of record, you may vote online at the Special Meeting or vote by proxy. Whether or not you plan to attend the Special Meeting, we urge you to vote by proxy over the telephone, on the internet as instructed below or by proxy using a proxy card that you may request or that we may elect to deliver at a later time to ensure your vote is counted.

Beneficial Owner. Shares Registered in the Name of a Broker or Bank

If on the Record Date your shares were held not in your name but rather in an account at a brokerage firm, bank, dealer, or other similar organization, then you are the beneficial owner of shares held in “street name” and the proxy materials are being forwarded to you by that organization. The organization holding your account is considered to be the stockholder of record for purposes of voting at the Special Meeting. As a beneficial owner, you have the right to direct your broker or other agent regarding how to vote the shares in your account. You are also invited to attend the Special Meeting. However, since you are not the stockholder of record, you may not vote your shares virtually at the Special Meeting unless you request and obtain a valid proxy from your broker or other agent.

How do I vote?

The procedures for voting are as follows:

If you are a stockholder of record, you may vote online at the Special Meeting, vote by proxy over the telephone, vote by proxy through the internet, or vote by proxy by mail using the enclosed proxy card. Whether or not you plan to attend the Special Meeting, we urge you to vote by proxy to ensure your vote is counted. You may still attend the Special Meeting and vote online even if you have already voted by proxy.

•To vote during the Special Meeting, if you are a stockholder of record as of the Record Date, follow the instructions at www.virtualshareholdermeeting.com/INTS2025SM. You will need to enter the 16-digit control number found on your proxy card or voting instruction form.

•To vote using the proxy card that may be delivered to you, simply complete, sign, and date the proxy card and return it promptly in the envelope provided. If you return your signed proxy card to us before the Special Meeting, we will vote your shares as you direct. If you sign the proxy card but do not specify how you want your shares voted, they will be voted in accordance with our board of directors’ recommendations as noted above.

•To vote over the telephone, dial toll-free 1-800-690-6903 and follow the recorded instructions. You will be asked to provide the control number from your proxy card or voting instruction form. Your telephone vote must be received by 11:59 p.m., Eastern time on October 21, 2025 to be counted.

•To vote through the internet, go to www.proxyvote.com to complete an electronic proxy card. You will be asked to provide the control number from the proxy card or voting instruction form. Your internet vote must be received by 11:59 p.m. Eastern time on October 21, 2025 to be counted.

If you are a beneficial owner of shares registered in the name of your broker, bank, or other agent, you should have received a full set of proxy materials containing voting instructions from that organization rather than from the Company. Simply follow the voting instructions in the proxy materials to ensure that your vote is counted. To vote online at the Special Meeting, you must obtain a valid proxy from your broker, bank, or other agent. Follow the instructions from your broker, bank, or other agent included with these proxy materials or contact your broker, bank, or other agent to request a proxy form.

How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you own as of the Record Date.

What happens if I do not vote?

If you are a stockholder of record and do not vote by completing your proxy card, by mail, by telephone, through the internet or online at the Special Meeting, your shares will not be voted.

If you are a beneficial owner and do not instruct your broker, bank, or other agent how to vote your shares, your broker, bank, or other agent will still be able to vote your shares in its discretion. In this regard, brokers, banks, and other securities intermediaries may use their discretion to vote your “uninstructed” shares with respect to matters considered to be “routine,” but not with respect to “non-routine” matters. The Amendment Proposal and Adjournment Proposal are considered “routine” matters, meaning that if you do not return voting instructions to your broker before its deadline, your shares may be voted by your broker in its discretion on the Amendment Proposal and Adjournment Proposal.

What are “broker non-votes”?

As discussed above, when a beneficial owner of shares held in “street name” does not give instructions to the broker or nominee holding the shares as to how to vote on matters deemed by applicable stock exchange rules to be “non-routine,” the broker or nominee cannot vote the shares. These unvoted shares are counted as “broker non-votes.”

What if I return a proxy card or otherwise vote but do not make specific choices?

If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted, as applicable, “FOR” the Amendment Proposal and “FOR” the Adjournment Proposal, in accordance with the recommendation of our board of directors. If any other matter is properly presented at the Special Meeting, your proxyholder (one of the individuals named on your proxy card) will vote your shares using his best judgment.

Who is paying for this proxy solicitation?

We will pay for the entire cost of soliciting proxies. In addition to these proxy materials, our directors and employees may also solicit proxies in person, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks, and other agents for the cost of forwarding proxy materials to beneficial owners.

What does it mean if I receive more than one full set of proxy materials?

If you receive more than one full set of proxy materials, your shares may be registered in more than one name or in different accounts. Please follow the voting instructions on each of the proxy cards or voting instruction forms to ensure that all of your shares are voted.

Can I change my vote after submitting my proxy?

Yes. You can revoke your proxy at any time before the final vote at the Special Meeting. If you are the record holder of your shares, you may revoke your proxy in any one of the following ways:

•You may submit another properly completed proxy card with a later date.

•You may grant a subsequent proxy by telephone or through the internet.

•You may send a timely written notice that you are revoking your proxy to Joseph Talamo, Intensity Therapeutics, Inc., 1 Enterprise Drive, Suite 430, Shelton, CT 06484.

•You may attend the Special Meeting and vote online. Simply attending the Special Meeting will not, by itself, revoke your proxy.

Your most current proxy card or telephone or internet proxy is the one that is counted.

If your shares are held by your broker or bank as a nominee or agent, you should follow the instructions provided by your broker or bank.

How many votes are needed to approve each proposal?

Votes will be counted by the inspector of election appointed for the Special Meeting. The minimum vote needed to approve each proposal and the effect of abstentions and broker non-votes is as follows:

•For Proposal 1, the Amendment Proposal, to be approved, the number of votes cast “FOR” the proposal must exceed the number of votes cast “AGAINST” the proposal; provided that our common stock is listed on The Nasdaq Stock Market LLC (“Nasdaq”) immediately before the Reverse Stock Split becomes effective and meets the listing requirements of Nasdaq relating to the minimum number of holders immediately after the Reverse Stock Split becomes effective (the “Listing Condition”), in which case, abstentions and any broker non-votes with respect to the Amendment Proposal will not be considered “votes cast” and will have no effect on the Amendment Proposal. If the Listing Condition is not met, the Amendment Proposal must receive the affirmative vote of the holders of a majority of our issued and outstanding shares of common stock as of the Record Date and abstentions and any broker non-votes with respect to the Amendment Proposal would have the same effect as a vote against the Amendment Proposal. Brokerage firms will have discretionary authority to vote their customers’ unvoted shares held by the firms in street name on the Amendment Proposal, and we do not anticipate receiving any broker non-votes on this proposal.

•For Proposal 2, the Adjournment Proposal, to be approved, the number of votes cast “FOR” the proposal must exceed the number of votes cast “AGAINST” the proposal. Abstentions and any broker non-votes with respect to the Adjournment Proposal will not be considered “votes cast” and will have no effect on the Adjournment Proposal. Brokerage firms will have discretionary authority to vote their customers’ unvoted shares held by the firms in street name on the Adjournment Proposal, and we do not anticipate receiving any broker non-votes on this proposal.

What if I do not specify how my shares are to be voted?

If you submit a proxy but do not indicate any voting instructions, the persons named as proxies will vote in accordance with the recommendations of our board of directors. Our board of directors’ recommendations are set forth above, as well as with the description of each proposal in this Proxy Statement.

What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding at least one-third of the voting power of the stock outstanding and entitled to vote at the meeting are present or represented by proxy. On the Record Date, there were 49,055,462 shares outstanding and entitled to vote. Thus, the holders of at least 16,351,821 shares must be present or represented by proxy at the Special Meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank, or other nominee) or if you vote online at the Special Meeting. Abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, the holders of a majority of the votes cast at the Special Meeting may adjourn the Special Meeting to another date.

How can I find out the results of the voting at the Special Meeting?

Preliminary voting results will be announced at the Special Meeting. In addition, final voting results will be published in a current report on Form 8-K that we expect to file within four business days after the Special Meeting. If final voting results are not available to us in time to file a Form 8-K within four business days after the Special Meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.