Mersana Therapeutics Reports Updated Data from the XMT-1536 Phase 1 Dose Escalation Study
- Well tolerated at doses up to 43 mg/m2 with encouraging activity in heavily pre-treated patient populations
- Favorable trend towards higher response rates with higher NaPi2b expression
- On track for interim disclosure of Phase 1 expansion cohort data in Q2 2020
“These data demonstrate that XMT-1536, our first-in-class Dolaflexin ADC targeting NaPi2b, delivers confirmed responses and durable stable disease in heavily pretreated ovarian cancer and NSCLC adenocarcinoma patients who have exhausted all other treatment options. These data also show that XMT-1536 is well tolerated without the severe toxicities of other ADC platforms such as neutropenia, neuropathy and ocular toxicity. Moreover, these data establish the potential for a biomarker-response relationship to identify patients most likely to benefit from XMT-1536,” said
Of the 59 patients enrolled, tumor types included 37 ovarian cancer, 11 NSCLC adenocarcinoma, and 11 other tumor types previously disclosed at lower dose levels. Patients were heavily pre-treated, with a median of five prior lines of treatment (range 1-10). These data include new patients dosed at 30, 36 and 43 mg/m2. The majority of the ovarian cancer patients had received prior bevacizumab or PARP inhibitors. All NSCLC adenocarcinoma patients had received prior platinum and immunotherapy. Updated and new data as of
• Safety profile consistent with previously reported data at lower doses.
- The most common treatment-related adverse events (TRAEs) were Grade 1-2 nausea, fatigue, headache and the most frequent Grade 3 TRAE was transient AST elevation.
- There were no dose limiting toxicities observed in the 43 mg/m2 cohort.
- There was no reported severe neutropenia, peripheral neuropathy or ocular toxicity.
• Additional confirmed responses in heavily pretreated patients and favorable biomarker-response trend observed.
- First confirmed partial response seen in a NSCLC adenocarcinoma patient with prior treatments including carboplatin, pemetrexed, paclitaxel and nivolumab.
- At the 43 mg/m2 dose level, 2/7 (29%) patients achieved partial responses (PRs) and 4/7 (57%) patients achieved stable disease (SD) for a disease control rate (DCR) of 6/7 (86%). In
January 2020, the expansion portion of the Phase 1 study dose was amended from 36 mg/m2 to 43 mg/m2 for newly enrolled patients.
- For the subset of evaluable patients treated at >30 mg/m2 who had higher NaPi2b expression, 5/15 (33%) achieved PR and 6/15 (40%) achieved SD for a DCR of 11/15 (73%).
- In contrast, for the subset of evaluable patients treated at >30 mg/m2 who had lower NaPi2b expression, 0/9 (0%) achieved PR and 5/9 (55%) achieved SD for a DCR of 5/9 (55%).
|Response - Ovarian Cancer
|PR||1 (10%)||0 (0%)||0 (0%)||1 (100%)|
|SD||6 (60%)||4 (57%)||2 (100%)||0 (0%)|
|DCR (PR+SD)||7 (70%)||4 (57%)||2 (100%)||1 (100%)|
|30, 36, 40 mg/m2||N||22||12||7||3|
|PR||3 (14%)||3 (25%)||0 (0%)||0 (0%)|
|SD||10 (45%)||6 (50%)||3 (43%)||1 (33%)|
|DCR (PR+SD)||13 (59%)||9 (75%)||3 (43%)||1 (33%)|
|PR||2 (29%)||2 (67%)||0 (0%)||0 (0%)|
|SD||4 (57%)||0 (0%)||2 (100%)||2 (100%)|
|DCR (PR+SD)||6 (86%)||2 (67%)||2 (100%)||2 (100%)|
*Excludes 3 patients discontinued due to investigator/patient choice and 1 without RECIST scan
**Hypocellular specimen/indeterminate for H-score or not determined yet
O Higher NaPi2b Expression: at / above lowest H-score at which response observed (>110)
OO Lower NaPi2b Expression: below the lowest H-score at which response observed (<110)
Mersana plans to enroll approximately 45 patients in each of the ovarian cancer and NSCLC adenocarcinoma patient cohorts in the expansion portion of the XMT-1536 Phase 1 study. The Company expects to present interim data from the dose expansion study in the second quarter of 2020.
Conference Call Details
This press release contains “forward-looking” statements within the meaning of federal securities laws. These forward-looking statements are not statements of historical facts and are based on management’s beliefs and assumptions and on information currently available to management. Forward-looking statements include information concerning the Company’s business strategy and the design, progression and timing of its clinical trials. Forward-looking statements generally can be identified by terms such as “anticipates,” “believes,” “could,” “seeks,” “estimates,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would” or similar expressions and the negatives of those terms. Forward-looking statements represent management’s beliefs and assumptions only as of the date of this press release. The Company’s operations involve risks and uncertainties, many of which are outside its control, and any one of which, or combination of which, could materially affect its results of operations and whether the forward-looking statements ultimately prove to be correct. Factors that may materially affect the Company’s results of operations and whether these forward-looking statements prove to be correct include, among other things, that preclinical testing may not be predictive of the results or success of ongoing or later preclinical or clinical trials, that the development and testing of the Company’s product candidates and new platforms will take longer and/or cost more than planned, including as a result of any impact of the current pandemic, and that the identification of new product candidates will take longer than planned, as well as those listed in the Company’s Annual Report on Form 10-K filed on
Investor & Media Contact
Source: Mersana Therapeutics, Inc.