Mersana Therapeutics, Inc.

June 23, 2023

Principle Contacts

Jeffrey P. Campisi

JCampisi@kaplanfox.com

NEW YORK, NY – June 23, 2023 – Kaplan Fox & Kilsheimer LLP (www.kaplanfox.com) 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 jcampisi@kaplanfox.com 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. 

WHY CONTACT KAPLAN FOX – Kaplan Fox is a leading national law firm focusing on complex litigation with offices in New York, Oakland, Los Angeles, Chicago and New Jersey.  With over 50 years of experience in securities litigation, Kaplan Fox offers the professional experience and track record that clients demand.  Through prosecuting cases on the federal and state levels, Kaplan Fox has successfully shaped the law through winning many important decisions on behalf of our clients.  For more information about Kaplan Fox & Kilsheimer LLP, you may visit our website at www.kaplanfox.com. 

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

Jeffrey P. Campisi
KAPLAN FOX & KILSHEIMER LLP
800 Third Avenue, 38th Floor
New York, New York 10022
(646) 315-9003
E-mail:  jcampisi@kaplanfox.com

Laurence D. King
KAPLAN FOX & KILSHEIMER LLP
1999 Harrison Street, Suite 1560
Oakland, California 94612
(415) 772-4704
Fax:  (415) 772-4707
E-mail: lking@kaplanfox.com