Company: INTS
Filing Date: 2025-06-12
Form Type: 424B5
Source: 0001628280-25-031040
Chunk: 1

Company: INTENSITY THERAPEUTICS, INC.
Filing Date: 2025-06-12
Form: 424B5
Chunk 1
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 any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

|                                  |     | Per Share |       |     | Total |           |
|:---------------------------------|:----|:----------|------:|:----|:------|----------:|
| Public offering price            |     | $         | 0.300 |     | $     | 2,002,500 |
| Underwriting discount(1)         |     | $         | 0.021 |     | $     |   140,175 |
| Proceeds, before expenses, to us |     | $         | 0.279 |     | $     | 1,862,325 |

(1) Underwriting discounts and commissions do not include a non-accountable expense allowance equal to 1.0% of the public offering price payable to the underwriters. See “ Underwriting ” page S- 22 of this prospectus supplement for a description of the compensation payable to the underwriter.

We have granted a 45-day option to the representative of the underwriters to purchase up to 1,001,250 additional shares of common stock solely to cover over-allotments, if any.

The underwriter expects to deliver the shares of common stock against payment on or about June 13, 2025.

| ThinkEquity |

<div align='center'>The date of this prospectus supplement is June 11, 2025.</div>

### TABLE OF CONTENTS
| Prospectus Supplement                             |     | Page |
| About This ProspectusSupplement                   |     | S-1  |
| Special Note Regarding Forward-Looking Statements |     | S-2  |
| Prospectus Supplement Summary                     |     | S-4  |
| The Offering                                      |     | S-8  |
| Risk Factors                                      |     | S-9  |
| Use of Proceeds                                   |     | S-12 |
| Dilution                                          |     | S-13 |
| Dividend Policy                                   |     | S-15 |
| Description of Securities Offered                 |     | S-16 |
| MaterialU.S. Federal Income Tax Considerations    |     | S-17 |
| Underwriting                                      |     | S-22 |
| Legal Matters                                     |     | S-30 |
| Experts                                           |     | S-30 |
| Where