Mersana Therapeutics, Inc.

June 23, 2023

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Jeffrey P. Campisi

NEW YORK, NY – June 23, 2023 – Kaplan Fox & Kilsheimer LLP ( is investigating potential claims on behalf of investors who purchased Mersana Therapeutics, Inc. (Nasdaq: MRSN) securities. Click Here To Join Investigation.

If you purchased Mersana securities and would like to discuss our investigation, please click here, or contact us by emailing or calling (212) 329-8571. 

On June 15, 2023, Mersana, a clinical-stage biopharmaceutical company, announced that “the U.S. Food and Drug Administration (FDA) has issued a partial clinical hold pausing new patient enrollment in UP-NEXT and UPGRADE-A, the company’s ongoing clinical trials of UpRi in platinum-sensitive ovarian cancer.  UPLIFT, Mersana’s ongoing clinical trial of UpRi in platinum-resistant ovarian cancer, completed enrollment in October 2022.”  The June 15 press release issued by the company states that “[t]he partial clinical hold follows a submission by Mersana of a recent aggregate safety report of all patients dosed with UpRi (approximately 560 patients) evaluating bleeding events.” As stated in the release, “Mersana’s recent assessment determined that serious bleeding events appear to occur at a higher rate than background.  While most bleeding cases in this aggregate safety analysis were low-grade, five (<1%) Grade 5 (fatal) bleeding events were observed among the approximately 560 patients dosed to date.  The causes of bleeding events remain under investigation.” 

Mersana’s stock price fell $5.66 per share, or 59.27%, to close at $3.89 per share on June 15, 2023 in response to the news issued in the press release. 

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If you have any questions about this investigation, please contact: 

Jeffrey P. Campisi
800 Third Avenue, 38th Floor
New York, New York 10022
(646) 315-9003

Laurence D. King
1999 Harrison Street, Suite 1560
Oakland, California 94612
(415) 772-4704
Fax:  (415) 772-4707

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