On August 21, 2019 Mersana Therapeutics, Inc. (NASDAQ:MRSN), a clinical-stage biopharmaceutical company focused on discovering and developing a pipeline of antibody drug conjugates (ADCs) targeting cancers in areas of high unmet medical need, reported the dosing of the first patient in the expansion portion of the Phase 1 study of XMT-1536, its first-in-class, wholly-owned Dolaflexin ADC targeting NaPi2b (Press release, Mersana Therapeutics, AUG 21, 2019, View Source [SID1234538905]). The expansion cohorts will assess the efficacy, safety and tolerability of XMT-1536 at 36 mg/m2 every four weeks in patients with platinum-resistant ovarian cancer and NSCLC adenocarcinoma. The Company also announced that it has not determined a maximum tolerated dose and that it plans to continue the dose escalation portion of the study in parallel.

Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:

Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing

                  Schedule Your 30 min Free Demo!

"The initiation of the expansion cohorts is an important milestone for Mersana. We have chosen a dose that continues to show a promising efficacy and tolerability profile in heavily pretreated patients without selecting for NaPi2b expression," said Anna Protopapas, President and CEO of Mersana Therapeutics. "The advancement of XMT-1536 brings us one step closer to proof of concept and our goal of significantly improving outcomes for people living with cancer."

"We are excited to move our study into this important next phase of clinical development. With additional sites participating in the expansion cohorts we look forward to establishing the benefits of XMT-1536 in larger, more defined patient populations with high unmet medical need," said Dirk Huebner, M.D., Chief Medical Officer of Mersana Therapeutics. "In addition, because we have not determined a maximum tolerated dose and have not observed the severe toxicities seen with other ADC platforms (e.g., neutropenia, peripheral neuropathy or ocular toxicity), we plan to continue dose escalation and will begin dosing patients at 43 mg/m2. Taken together, these data will provide critical information to guide our path to registration for XMT-1536."

The expansion study includes two patient cohorts. One is enrolling platinum-resistant ovarian cancer patients who have failed standard therapy and have had no more than three lines of prior therapy. The other cohort is enrolling NSCLC adenocarcinoma patients who have failed front line platinum-based chemotherapy, either in combination or sequentially treated with an anti-PD-1 or anti-PD-L1 therapy. Patients in the expansion portion of the XMT-1536 Phase 1 study will be treated with the 36 mg/m2 once-every-four-week dosing regimen. Patients will not be pre-selected for NaPi2b expression, but eligibility criteria require archived tumor samples and fresh tumor biopsies when medically feasible. The study aims to enroll approximately 45 patients in each cohort.

Additional information can be found at: View Source;rank=1

About XMT-1536

XMT-1536 is a first-in-class ADC targeting the sodium-dependent phosphate transport protein (NaPi2b) and utilizing the Dolaflexin platform to deliver an average of 10-15 DolaLock payload molecules per antibody. The NaPi2b antigen is broadly expressed in non-small cell lung cancer (NSCLC) adenocarcinoma and ovarian cancer. XMT-1536 is in Phase 1 clinical trials in patients with tumors expressing NaPi2b, including ovarian cancer and NSCLC adenocarcinoma. More information on the ongoing Phase 1 clinical trial can be found at clinicaltrials.gov (NCT03319628).