SELLAS Life Sciences Group, Inc. (Nasdaq: SLS) (“SELLAS” or the
“Company”), a late-stage clinical biopharmaceutical company focused
on the development of novel cancer immunotherapies for a broad
range of cancer indications, today announced initial data from two
clinical studies of galinpepimut-S (GPS), the Company’s Wilms
Tumor-1 (WT1)-targeting peptide immunotherapeutic, in combination
with checkpoint inhibitor therapies in patients with two different
types of advanced solid cancers who had exhausted their standard
therapy options.
In the first study, a phase 1/2 ‘basket’ trial of GPS in
combination with the checkpoint inhibitor pembrolizumab (Keytruda),
which is conducted under a Clinical Trial Collaboration and Supply
Agreement with Merck & Co., Inc., Kenilworth, N.J., USA (known
as MSD outside the United States and Canada), the first set of
evaluable patients (n = 8) diagnosed with 2nd or 3rd line WT1(+)
relapsed or refractory metastatic ovarian cancer demonstrated a
disease control rate (the sum of overall response rate and rate of
stable disease) of 87.5% with a median follow-up of 9.4 weeks. In
this difficult to treat patient population, at the first assessment
time-point of 6 weeks post-therapy initiation, 100% of the patients
were free of disease progression. Using a validated
immunohistochemistry (IHC) assay during the screening period, the
rate of WT1 positivity in this ovarian cancer patient population
was approximately 70%. Six of the eight evaluable patients are
continuing to receive GPS plus pembrolizumab. Enrollment is
continuing with a target of a total of 20 patients. More mature
clinical and immunobiological data are expected to be announced by
the end of the second quarter of 2021.
In the second study, a Phase 1 investigator-sponsored clinical
trial (IST) of GPS in combination with the checkpoint inhibitor
nivolumab (Opdivo) in patients with macroscopic measurable deposits
of malignant pleural mesothelioma (MPM) who were either refractory
to or relapsed after frontline tri-modality standard therapy, the
first set of evaluable patients (n = 3) had a median progression
free survival of at least 10 weeks since therapy initiation. In
primary refractory MPM patients, any prolongation of
progression-free interval greater than 8 weeks would be considered
clinically meaningful, considering the current lack of effective
therapies. All patients had the epithelioid variant of MPM, a tumor
which is universally expressing WT1. Moreover, in this
study, GPS was found to be appropriately immunogenic, leading to
the emergence of antigen (WT1)-specific CD4+ T-memory cell
responses at 3 months post-therapy initiation. Additional MPM
patients are currently being enrolled; completion of study
enrollment (target total n = 10) and more mature clinical and
immunobiological data are expected by the end of the second quarter
of 2021.
In both studies, the safety profile of the combination of GPS
with the checkpoint inhibitor was similar to that seen with
checkpoint inhibitors alone, with the addition of only low grade,
transitory local reactions at the site of injection of GPS,
consistent with previously performed clinical studies of GPS.
“These early data confirm the tolerability profile seen in
earlier studies of GPS, which is one of the primary endpoints in
these solid cancer trials, in a variety of cancer indications, even
in the most refractory patients who underwent numerous prior
therapies,” commented Jeffrey S. Weber, MD, PhD, Deputy Director of
the Perlmutter Cancer Center at New York University (NYU)-Langone
Health, co-Director of its Melanoma Research Program Center and
Chair of SELLAS’ Scientific Advisory Board. “These safety findings
are accompanied by promising early indications of an efficacy
signal for patients with advanced metastatic disease, whose
management is extremely challenging even with checkpoint inhibitor
monotherapy.”
“We are encouraged by the data shown in these two studies of GPS
in combination with checkpoint inhibitors and look forward to
additional data from these studies,” stated Dragan Cicic, MD,
Senior Vice President, Clinical Development of SELLAS. “We now have
early evidence that supports further expanding the field of
potential GPS indications into solid cancers with high rates of WT1
positivity. GPS has previously been shown to invoke
multi-epitope, broad cross-reactivity along the full-length of the
WT1 protein, suggestive of epitope spreading, and immunologically
mediated cancer cell destruction, which are hallmarks of an
effective cancer vaccine. The scientific rationale in combining GPS
with checkpoint inhibitors is the immunbiologic and pharmacodynamic
synergy between the two agents, whereby the negative influence of
the tumor microenvironment is mitigated by checkpoint inhibitors
and thus allowing the patients’ own immune cells specifically
sensitized against WT1, by GPS, to invade and destroy cancerous
cells.”
About the Phase 1/2 Basket Study of GPS in Combination
with Pembrolizumab (Keytruda®) in Patients with Selected
WT1-Positive Advanced Cancers, Including Ovarian
Cancer
This is a Phase 1/2 open-label, multicenter, multi-arm study
conducted under a Clinical Trial Collaboration and Supply Agreement
(CTSA) with Merck & Co., Inc., Kenilworth, N.J., USA (known as
MSD outside the United States and Canada) to assess the efficacy
and safety of the combination of GPS and pembrolizumab (Keytruda®)
(ClinicalTrials.gov identifier: NCT03761914). The primary endpoints
of the study include safety and overall response rate, while
secondary endpoints include progression-free survival, overall
survival and immune response correlates. The study will enroll
approximately 90 patients at up to 20 centers in the United States.
The trial is currently evaluating patients with ovarian cancer
(second or third line).
About the Phase 1 Trial of GPS in Combination with
Nivolumab (Opdivo®) in Patients with Malignant Pleural Mesothelioma
(MPM)
This is a Phase 1 open-label clinical study conducted by
Memorial Sloan Kettering Cancer Center (MSK) and is enrolling
patients with MPM who harbor relapsed or refractory disease after
having received frontline, standard-of-care multimodality therapy
(target total n = 10; ClinicalTrials.gov identifier: NCT04040231).
The principal investigator for the study is Marjorie G. Zauderer,
MD, Co-Director, Mesothelioma Program and Associate Attending
Physician in the Thoracic Oncology Service, Department of Medicine
at MSK. The trial is investigating the potential of GPS in
combination with nivolumab (Opdivo®) to demonstrate anti-tumor
immune responses and meaningful clinical activity in the presence
of macroscopic advanced disease in MPM patients and gauging the
degree of clinical benefit by assessment of the overall response
rate with the combination in comparison with that reported with
nivolumab alone in historical comparable patient populations.
Keytruda® is a registered trademark of Merck Sharp & Dohme
Corp., a subsidiary of Merck & Co., Inc., Kenilworth, N.J.,
USA, and is not a trademark of SELLAS. The manufacturer of this
brand is not affiliated with and does not endorse SELLAS or its
products. Opdivo® is a registered trademark of Bristol Myers
Squibb, and is not a trademark of SELLAS. The manufacturer of this
brand is not affiliated with and does not endorse SELLAS or its
products.
About SELLAS Life Sciences Group, Inc.
SELLAS is a late-stage clinical biopharmaceutical company
focused on the development of novel cancer immunotherapeutics for a
broad range of cancer indications. SELLAS’ lead product candidate,
GPS, is licensed from MSK and targets the WT1 protein, which is
present in an array of tumor types. GPS has potential as a
monotherapy or in combination to address a broad spectrum of
hematologic malignancies and solid tumor indications. SELLAS’
second product candidate, nelipepimut-S, is a HER2-directed cancer
immunotherapy with potential for the treatment of patients with
early-stage breast cancer with low to intermediate HER2 expression,
otherwise known as HER2 1+ or 2+, which includes triple negative
breast cancer patients, following standard of care.
For more information on SELLAS, please visit
www.sellaslifesciences.com.
Forward-Looking Statements
This press release contains forward-looking statements. All
statements other than statements of historical facts are
“forward-looking statements,” including those relating to future
events. In some cases, forward-looking statements can be identified
by terminology such as “plan,” “expect,” “anticipate,” “may,”
“might,” “will,” “should,” “project,” “believe,” “estimate,”
“predict,” “potential,” “intend,” or “continue” and other words or
terms of similar meaning. These statements include, without
limitation, statements related to the clinical development of GPS
for various cancer indications, including ovarian cancer and MPM,
and the potential for GPS as a drug development candidate. These
forward-looking statements are based on current plans, objectives,
estimates, expectations and intentions, and inherently involve
significant risks and uncertainties. Actual results and the timing
of events could differ materially from those anticipated in such
forward-looking statements as a result of these risks and
uncertainties, which include, without limitation, risks and
uncertainties associated with the COVID-19 pandemic and its impact
on the Company’s clinical plans, risks and uncertainties associated
with immune-oncology product development and clinical success
thereof, the uncertainty of regulatory approval, and other risks
and uncertainties affecting SELLAS and its development programs as
set forth under the caption “Risk Factors” in SELLAS’ Annual Report
on Form 10-K filed on March 13, 2020 and in its other SEC filings.
Other risks and uncertainties of which SELLAS is not currently
aware may also affect SELLAS’ forward-looking statements and may
cause actual results and the timing of events to differ materially
from those anticipated. The forward-looking statements herein are
made only as of the date hereof. SELLAS undertakes no obligation to
update or supplement any forward-looking statements to reflect
actual results, new information, future events, changes in its
expectations or other circumstances that exist after the date as of
which the forward-looking statements were made.
Investor ContactsAdam HoldsworthPCG
Advisory917-497-9287adamh@pcgadvisory.com
Investor RelationsSELLAS Life Sciences Group,
Inc.917-438-4353info@sellaslife.com
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