Shares of Cambridge, Mass.-based Mersana Therapeutics are up more than 7 percent in premarket trading after the company announced that it will be able to continue with its Phase I trial studying the antibody drug conjugate XMT-1522 as a potential treatment for some breast cancer patients.
Shares of Cambridge, Mass.-based Mersana Therapeutics are up more than 7 percent in premarket trading after the company announced that it will be able to continue with its Phase I trial studying the antibody-drug conjugate XMT-1522 as a potential treatment for some breast cancer patients.
The U.S. Food and Drug Administration (FDA) placed a partial clinical hold on the trial in July following the death of a patient. In July, the company said the patient had received a “dose level 7” of XMT-1522 and added that the death could potentially be related to the medication. Now though, after reaching an agreement with the regulatory agency on trial protocol changes, including increased monitoring as well as the exclusion of patients with advanced hepatic impairment, Mersana will be able to proceed with the trial.
“We are excited to resume enrollment on the XMT-1522 trial and to work with investigators to explore the full potential of both promising drug candidates in the solid tumor setting,” Mersana Chief Executive Officer Anna Protopapas said in a statement.
XMT-1522 is a Dolaflexin ADC targeting HER2-expressing tumors that is being co-developed with Takeda Pharmaceutical. The company is exploring XMT-1522 as a potential treatment for HER2-expressing breast cancer, non-small cell lung cancer (NSCLC), and gastric cancer. XMT-1522 includes a proprietary HER2 antibody which is conjugated with Mersana’s Dolaflexin platform – a Fleximer polymer linked with a proprietary auristatin payload. The platform allows for the attachment of an extensive range of anti-tumor payloads to Fleximer. The ADC is designed to remain stable in the bloodstream and to release the drug payloads once inside the targeted cell, according to company data.
As the XMT-1522 trial moves forward, Mersana said it will evaluate alternative dosing levels. The XMT-1522 trial will begin with a once-every-four-week dose regimen.
Mersana added that it will implement the same protocols in its XMT-1522 trial in trials with XMT-1536, an ADC targeting NaPi2b, an antigen highly expressed in the majority of non-squamous NSCLC and epithelial ovarian cancer. XMT-1536 is currently in Phase 1 clinical trials for NaPi2b-expressing cancers, including ovarian cancer, non-small cell lung cancer and other cancers. Data on XMT-1536 is expected in the first half of 2019. Mersana said the alternative dosing levels that will be implemented in the XMT-1522 trial have already been executed in the XMT-1536 trial at “previously explored dose levels in order to enable a comparison of relevant doses and their impact on the safety, efficacy and PK profile of the drug candidate.” Mersana began dosing patients with NaPi2b-expressing tumors in the Phase 1 study in December 2017.
Shares of Mersana Therapeutics are up to $15.50 in premarket trading. The stock closed at $14.38 on Friday.
