XMT-1536, a first-in-class ADC targeting the sodium-dependent phosphate transport protein NaPi2b, utilizes the Dolaflexin platform to deliver an average of 10-12 DolaLock payload molecules per antibody. The NaPi2b antigen is broadly expressed in ovarian cancer and non-small cell lung cancer (NSCLC) adenocarcinoma. XMT-1536 is in a Phase 1 proof-of-concept clinical trial in patients with ovarian cancer and NSCLC adenocarcinoma.

Data from the dose escalation portion of the XMT-1536 Phase 1 study were presented in March 2020 and showed encouraging clinical activity with confirmed responses and prolonged stable disease in heavily pretreated patients, without pre-selection for NaPi2b expression. These data showed that XMT-1536 was well-tolerated without the severe toxicities commonly seen with other ADCs such as neutropenia, ocular toxicities, or peripheral neuropathy. 

Interim data from the expansion portion of the ongoing XMT-1536 Phase 1 study were presented at the ASCO virtual meeting in May 2020. Updated interim data from the ovarian cancer cohort of the XMT-1536 Phase 1 Expansion Study were presented at the ESMO virtual meeting in September 2020. These data showed promising anti-tumor activity with confirmed complete responses, partial responses and durable stable disease in platinum-resistant ovarian cancer patients and a safety profile consistent with previously reported dose escalation data with no new safety signals observed.


We continue to enroll ovarian cancer and NSCLC adenocarcinoma patients in the expansion portion of the Phase 1 study. The expansion study is designed to demonstrate proof of concept and inform the path to approval in these indications with high unmet medical need.

In August 2020, the U.S. Food and Drug Administration (FDA) granted Fast Track Designation for XMT-1536, for the treatment of patients with platinum-resistant high-grade serous ovarian cancer who have received up to three prior lines of systemic therapy or patients who have received four prior lines of systemic therapy regardless of platinum status.

For more information on this clinical trial, visit clinicaltrials.gov (NCT03319628). 

Expanded Access Policy:

Expanded access, or compassionate use, is the use of an investigational medicine prior to regulatory approval and outside of a clinical trial. Mersana does not currently have an expanded access program or compassionate use program for any of our investigational products. We understand that for people living with cancer, waiting for an approved treatment can be difficult. We believe that devoting ourselves to current and future clinical trial programs is the best path to meet our goal of providing therapeutics to patients with cancer. We encourage any person with cancer interested in gaining access to our investigational therapies to consult with their physicians regarding the possibility of participating in one of our clinical trials.