Mersana Therapeutics Reports Updated Interim Data from the Ovarian Cancer Cohort of the XMT-1536 Phase 1 Expansion Study
September 17 2020 - 06:00AM
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, today reported updated interim
safety, tolerability and efficacy data for the ovarian cancer
cohort of the ongoing expansion portion of the Phase 1 study
evaluating XMT-1536, its first-in-class ADC candidate targeting
NaPi2b, as part of the 2020 European Society of Medical Oncology
(ESMO) Virtual Congress. The Company will host a conference call
and webcast today at 8:00 a.m. ET, during which
investigator Erika Hamilton, MD, Director of the Breast Cancer and
Gynecologic Cancer Research Program from the Sarah Cannon Research
Institute at Tennessee Oncology, and members of the Mersana
executive team will present and discuss these data.
“These data further support the continued
development of XMT-1536, our first-in-class Dolaflexin ADC
targeting NaPi2b, which has recently been granted FDA Fast Track
Designation. We are eager to advance XMT-1536 into
registration-enabling studies based on its observed antitumor
activity and favorable safety profile in an ovarian cancer
population with a very poor prognosis and limited treatment
options,” said Anna Protopapas, President and Chief Executive
Officer of Mersana Therapeutics. “Additionally, we look forward to
presenting more comprehensive and mature results from the ongoing
expansion cohort around the end of this year.”
This interim analysis focused on the ovarian
cancer cohort of the Phase 1 expansion study, including heavily
pre-treated patients with platinum-resistant or refractory ovarian
cancer, fallopian tube or primary peritoneal cancer who have
received up to three lines of prior therapy, and in some cases four
lines of prior therapy regardless of platinum status. With a data
cutoff of August 18, 2020 these data include 47 patients. These
data include additional follow up on the 27 ovarian cancer patients
previously presented at the American Society of Clinical Oncology
(ASCO) virtual program in May of 2020 as well as 20 new patients
who entered the study between May 1, 2020 and August 18, 2020.
Key findings include:
• |
Safety profile consistent with previously reported expansion data
and no new safety signals observed |
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The most frequently reported treatment-related adverse events
(TRAEs) were generally Grade 1-2 fatigue, nausea, decreased
appetite, vomiting and transient AST elevation without associated
changes in bilirubin or cases of Hy’s law. |
|
o |
There were no reported cases of severe neutropenia, peripheral
neuropathy or ocular toxicity. |
|
|
|
|
• |
Continued, significant anti-tumor activity in platinum-resistant
and platinum-refractory ovarian cancer and in ovarian cancer
previously treated with bevacizumab, PARP inhibitors, or both |
|
o |
Of the 29 patients that were evaluable for response, 2/29 (7%)
achieved confirmed complete responses (CRs) and 8/29 (28%) achieved
confirmed partial responses (PRs) for an objective response rate
(ORR) of 34%. Additionally, 13/29 (45%) patients achieved stable
disease (SD); the disease control rate (DCR) was 23/29 (79%). |
|
|
• |
70% of responses were observed within two cycles and 100% of
responses were observed within four cycles. Responses appeared to
deepen over time, including responses in patients receiving reduced
dose levels. |
|
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• |
The majority of responders had prior treatment with bevacizumab,
PARP inhibitors, or both. Both patients with confirmed CRs had
prior treatment with bevacizumab and PARP inhibitors. |
|
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• |
Reduction in tumor volume was observed in the majority of patients
achieving a best response of stable disease. |
|
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• |
Data continue to support a NaPi2b biomarker-based patient selection
strategy based on depth, time on study and quality of response |
|
o |
50% of patients with higher NaPi2b expression are ongoing in the
study while only 33% of patients with lower Napi2b expression are
ongoing in study. Median duration of response was not yet reached
in the 7 patients with ovarian cancer with higher NaPi2b
expression. |
|
o |
The Company expects to define the patient selection strategy based
on the total data set from patients treated with XMT-1536. |
Conference Call DetailsMersana
Therapeutics will host a conference call and webcast today at 8:00
a.m. ET to discuss these data. To access the call, please dial
877-303-9226 (domestic) or 409-981-0870 (international) and provide
the Conference ID 5731456. A live webcast of the presentation will
be available on the Investors & Media section of the Mersana
website at www.mersana.com.
About Mersana
TherapeuticsMersana Therapeutics is a clinical-stage
biopharmaceutical company using its differentiated and proprietary
ADC platforms to rapidly develop novel ADCs with optimal efficacy,
safety and tolerability to meaningfully improve the lives of people
fighting cancer. Mersana’s lead product candidate, XMT-1536, is in
the expansion portion of a Phase 1 proof-of-concept clinical study
in patients with ovarian cancer and NSCLC adenocarcinoma. XMT-1592,
Mersana’s second ADC product candidate targeting NaPi2b-expressing
tumors, was created using Mersana’s customizable and homogeneous
Dolasynthen platform and is in the dose escalation portion of a
Phase 1 proof-of-concept clinical study. The Company’s early stage
programs include a B7-H4 targeting ADC, as well as a STING-agonist
ADC developed using the Company’s Immunosynthen platform. In
addition, multiple partners are using Mersana’s Dolaflexin platform
to advance their ADC pipelines.
Forward-Looking StatementsThis
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 “aims,” “anticipates,” “believes,” “contemplates,”
“continues,” “could,” “estimates,” “expects,” “goal,” “intends,”
“may,” “on track,” “plans,” “possible,” “potential,” “predicts,”
“projects,” “seeks,” “should,” “target,” “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, 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 February 28, 2020, with the
Securities and Exchange Commission (“SEC”), the Company’s Quarterly
Report on Form 10-Q filed on May 8, 2020, with the SEC and
subsequent SEC filings. In addition, while we expect that the
COVID-19 pandemic might adversely affect the Company’s preclinical
and clinical development efforts, business operations and financial
results, the extent of the impact on the Company’s operations and
the value of and market for the Company’s common stock will depend
on future developments that are highly uncertain and cannot be
predicted with confidence at this time, such as the ultimate
duration of the pandemic, travel restrictions, quarantines,
physical distancing and business closure requirements in the U.S.
and in other countries, and the effectiveness of actions taken
globally to contain and treat the disease. Except as required by
law, the Company assumes no obligation to update these
forward-looking statements publicly, or to update the reasons
actual results could differ materially from those anticipated in
the forward-looking statements, even if new information becomes
available in the future.
Contact:
Investor & Media Contact Sarah
Carmody617-844-8577scarmody@mersana.com
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