XMT-1660 is a B7-H4-directed Dolasynthen ADC with a precise, target-optimized drug-to-antibody ratio (DAR 6) and a proprietary payload with controlled bystander effect. B7-H4 is overexpressed in a range of cancers, including breast, endometrial and ovarian tumors. 

In 2022, we initiated a multicenter Phase 1 trial to investigate the safety, tolerability and anti-tumor activity of XMT-1660 in patients with solid tumors, including in breast, endometrial and ovarian cancers. 

The U.S. Food and Drug Administration has granted Fast Track Designation to XMT-1660 for the treatment of adult patients with advanced or metastatic triple-negative breast cancer.

For more information about our Phase 1 trial of XMT-1660, visit clinicaltrials.gov (NCT05377996).

XMT-1660 symbol

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.