SAN
DIEGO, Dec. 13, 2021 /PRNewswire/ -- Poseida
Therapeutics, Inc. (Nasdaq: PSTX), a clinical-stage
biopharmaceutical company utilizing proprietary genetic engineering
platform technologies to create cell and gene therapeutics with the
capacity to cure, today reported interim results from its Phase 1/2
PRIME clinical trial of P-BCMA-101 for the treatment of
relapsed/refractory multiple myeloma (R/R MM) at the 2021 American
Society of Hematology (ASH) Annual Meeting.
The results show that P-BCMA-101, a non-viral transposon-based
autologous CAR-T, was well tolerated and demonstrated strong
anti-tumor activity in advanced, late line R/R MM patients. The
learnings from P-BCMA-101 informed the development of the Company's
first allogeneic program, P-BCMA-ALLO1 which is also being
evaluated in R/R MM patients. The Company previously announced that
it is winding down the P-BCMA-101 autologous program in favor of
the allogeneic program, P-BCMA-ALLO1.
"We are encouraged by the outcomes seen from our clinical trial
of P-BCMA-101, results that continue to validate our approach and
that have informed P-BCMA-ALLO1, our first fully allogeneic CAR-T
program for patients with multiple myeloma, as well as our other
programs. Our focus is on creating differentiated product
candidates with a high percentage of T stem cell memory (Tscm)
cells," said Eric Ostertag, M.D.,
Ph.D., chief executive officer of Poseida Therapeutics. "Looking
ahead, we continue to advance P-BCMA-ALLO1 and P-MUC1C-ALLO1 and
look forward to presenting data in 2022 for both of these
allogeneic programs."
The PRIME trial is a Phase 1/2, open label 3+3 single dose
escalation of P-BCMA-101 CAR-T cells. The primary objective of the
study is to determine the safety and maximum tolerated dose of
P-BCMA-101 based on dose limiting toxicities (DLT), and the key
secondary objective is to assess the anti-myeloma effect of the
product. The median patient age was 62, with a median time since
diagnosis of approximately 5.8 years. Patients were heavily
pre-treated, with a median of 7 prior lines of therapy (2-18). As
of the data cut-off date of October 15,
2021, a total of 98 patients have been dosed with
P-BCMA-101.
The best observed treatment regimen was a combination with
rituximab (n=14), with an overall response rate (ORR) of 78%, a
VGPR/sCR rate of 43% and 100% overall survival at the time of the
data cutoff. Progression free survival was also improved with
rituximab, with median overall survival rates not yet reached in
several cohorts including the rituximab combination cohorts.
Response rates for other cohorts are consistent with results
previously reported.
Across the study, no dose-limiting toxicities were observed. 28%
of patients developed cytokine release syndrome (CRS) and 7% of
patients developed neurotoxicity. None of the patients developed
Grade 3 or higher CRS, and 2% of patients developed Grade 3
neurotoxicity. There were no treatment-related deaths among the
patient population and no patients needed ICU admission as a result
of CAR-T related toxicities. 28 patients were treated on a
fully outpatient basis.
"P-BCMA-101 demonstrated strong anti-tumor activity in advanced
multiple myeloma patients, and cohorts to date have shown minimal
CRS and neurotoxicity, which allows for safe administration in an
outpatient environment and combinations with other therapies," said
Caitlin Costello, M.D., Associate
Clinical Professor of Medicine and member of the Division of Blood
and Marrow Transplantation at the University
of California, San Diego. "These data indicate that the
piggyBac transposon-based platform is an attractive option for
allogeneic CAR-T cells, which has led to a first-in-human Phase 1
study."
The Company's first fully allogeneic CAR-T cell product,
P-BCMA-ALLO1 utilizes Poseida's proprietary piggyBac® DNA delivery
system and Cas-CLOVER™ site-specific gene editing system to create
an allogeneic product that prevents both graft-vs-host and
host-vs-graft diseases and also incorporates a next-generation BCMA
binder. P-BCMA-ALLO1 manufacturing involves a proprietary "booster"
molecule that allows for numerous doses to be produced from a
single manufacturing run, while maintaining desirable Tscm cells,
which can reach percentages in the 60-80% range.
The Investigational New Drug (IND) application for P-BCMA-ALLO1
was given a safe to proceed designation by the FDA in August 2021. The Phase 1 study is an open label,
dose escalation study following a 3+3 design of dose escalation in
subjects with R/R MM. The study will assess the safety and maximum
tolerated dose of P-BCMA-ALLO1 based on dose limiting toxicities.
Key secondary objectives of the study include the anti-myeloma
effect and safety of P-BCMA-ALLO1.
About Poseida Therapeutics, Inc.
Poseida Therapeutics
is a clinical-stage biopharmaceutical company dedicated to
utilizing our proprietary genetic engineering platform technologies
to create next generation cell and gene therapeutics with the
capacity to cure. We have discovered and are developing a broad
portfolio of product candidates in a variety of indications based
on our core proprietary platforms, including our non-viral
piggyBac® DNA Delivery System, Cas-CLOVER™ Site-specific Gene
Editing System and nanoparticle- and AAV-based gene delivery
technologies. Our core platform technologies have utility, either
alone or in combination, across many cell and gene therapeutic
modalities and enable us to engineer our portfolio of product
candidates that are designed to overcome the primary limitations of
current generation cell and gene therapeutics. To learn more, visit
www.poseida.com and connect with us on Twitter and LinkedIn.
Forward-Looking Statement
Statements contained in this
press release regarding matters that are not historical facts are
"forward-looking statements" within the meaning of the Private
Securities Litigation Reform Act of 1995. Such forward-looking
statements include statements regarding, among other things, the
potential benefits of Poseida's technology platforms and product
candidates, Poseida's plans and strategy with respect to developing
its technologies and product candidates, and anticipated timelines
and milestones with respect to Poseida's development programs and
manufacturing activities. Because such statements are subject to
risks and uncertainties, actual results may differ materially from
those expressed or implied by such forward-looking statements.
These forward-looking statements are based upon Poseida's current
expectations and involve assumptions that may never materialize or
may prove to be incorrect. Actual results could differ materially
from those anticipated in such forward-looking statements as a
result of various risks and uncertainties, which include, without
limitation, risks and uncertainties associated with development and
regulatory approval of novel product candidates in the
biopharmaceutical industry and the other risks described in
Poseida's filings with the Securities and Exchange Commission. All
forward-looking statement contained in this press release speak
only as of the date on which they were made. Poseida undertakes no
obligation to update such statements to reflect events that occur
or circumstances that exist after the date on which they were made,
except as required by law.
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SOURCE Poseida Therapeutics, Inc.