XMT-2056 is a systemically-administered Immunosynthen STING agonist antibody drug conjugate (DAR 8) that is designed to target a novel HER2 epitope (distinct from pertuzumab and trasztuzumab) and locally activate STING signaling in both tumor-resident immune cells and in tumor cells (a “one-two punch”), providing the potential to treat patients with HER2-high or -low tumors as monotherapy or in combination with standard-of-care HER2 agents.​

In 2023, we initiated a multicenter Phase 1 open-label trial to investigate XMT-2056 in previously treated patients with advanced/recurrent solid tumors expressing HER2, including breast, gastric, colorectal and non-small-cell lung cancers. For more information about this trial, visit clinicaltrials.gov (NCT05514717).

The U.S. Food and Drug Administration (FDA) has granted orphan drug designation to XMT-2056 for the treatment of gastric cancer.


Expanded Access Policy Statement:

Patients with serious or life-threatening conditions occasionally request access to investigational agents outside of a clinical trial and prior to regulatory approval and commercial availability. These patients seek such access for any number of reasons, including failure of past treatments, intolerable side effects associated with their treatment, or because they do not meet the inclusion criteria for any ongoing clinical trial for their disease. 

Programs that allow for such access are known as Expanded Access Programs (EAPs) and are often also referred to as Early Access, Compassionate Use and Emergency Use. 

Currently, Mersana does not have an EAP for any of its investigational agents because we have not yet determined that there is sufficient clinical data to support granting expanded access. If Mersana ultimately adopts an EAP for one or more of its investigational agents, this Policy Statement will be updated accordingly.  In such event, Mersana will ensure that its EAP would comply with applicable legal and regulatory requirements. 

Questions regarding this Policy statement should be sent to medicalinformation@mersana.com. Information regarding Mersana’s clinical trials, as well as clinical trials and expanded access programs for other potential therapies, can be found on www.clinicaltrials.gov.