Company: RNAC
Filing Date: 2025-01-08
Form Type: 424B7
Source: 0001140361-25-000631
Chunk: 1

Company: Cartesian Therapeutics, Inc.
Filing Date: 2025-01-08
Form: 424B7
Chunk 1
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 this prospectus forms a part.

You should carefully read this prospectus and any applicable prospectus supplement before you invest in any of the securities being offered.

Our Common Stock is traded on the Nasdaq Global Market under the symbol “RNAC.” On January 7, 2025, the last reported sale price for our Common Stock was $17.16 per share.

Investing in our securities involves a high degree of risk. Before investing in our securities, you should carefully consider the risks and uncertainties described under the caption “**

#### Risk Factors

#### ” beginning on page

#### 9
**of this prospectus and any similar section contained in the applicable prospectus supplement and in any free writing prospectus we have authorized for use in connection with a specific offering, and under similar headings in the documents incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.**

#### The date of this prospectus is January 8, 2025.
TABLE OF CONTENTS

TABLE OF CONTENTS

| ABOUT THIS PROSPECTUS                                |     |  1 |
| CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS |     |  2 |
| WHERE YOU CAN FIND MORE INFORMATION                  |     |  4 |
| INCORPORATION BY REFERENCE                           |     |  5 |
| THE COMPANY                                          |     |  6 |
| THE OFFERING                                         |     |  7 |
| RISK FACTORS                                         |     |  9 |
| USE OF PROCEEDS                                      |     | 10 |
| DESCRIPTION OF CAPITAL STOCK                         |     | 11 |
| SELLING STOCKHOLDERS                                 |     | 18 |
| PLAN OF DISTRIBUTION                                 |     | 24 |
| LEGAL MATTERS                                        |     | 27 |
| EXPERTS                                              |     | 28 |

i

#### TABLE OF CONTENTS

### ABOUT THIS PROSPECTUS
This prospectus is part of a registration statement that we filed with the SEC using a “shelf” registration process. Under this shelf registration process, the Selling Stockholders may, from time to time, sell the securities described in this prospectus in one or more offerings.

This prospectus contains information that you should consider when making your investment decision. Neither we nor the Selling Stockholders have authorized anyone