Reactivation of P-BCMA-101 CAR-T cells
and a repeat stringent complete response (sCR) more than 3 years
after original CAR-T therapy
Demonstrates potential of stem cell memory T
cells (TSCM), a key differentiator for Poseida's CAR-T
programs
SAN
DIEGO, Sept. 4, 2024 /PRNewswire/ -- Poseida
Therapeutics, Inc. (Nasdaq: PSTX), a clinical-stage allogeneic cell
therapy and genetic medicines company advancing differentiated
non-viral treatments for patients with cancer and rare diseases,
highlighted new data from a case study of a patient with relapsed
multiple myeloma treated in a clinical trial of P-BCMA-101, the
Company's original investigational T stem cell memory
(TSCM)-rich BCMA targeting autologous CAR-T cell
therapy. The data were presented in an oral session at the Society
of Hematologic Oncology (SOHO) Twelfth Annual Meeting in
Houston.
"This case study demonstrates the remarkable potential of T stem
cell memory-based therapies, providing a strong anti-myeloma
response with a long-term remission and notably CAR-T cell
persistence," said Thomas G. Martin,
M.D., Clinical Professor of Medicine, Adult Leukemia and Bone
Marrow Transplantation Program and Director of Hematology, Blood
and Marrow Transplantation and Cellular Therapy at UCSF, and
co-leader of the Cancer Immunology & Immunotherapy Program at
the UCSF Helen Diller Family Comprehensive Cancer Center. "Most
notably, we believe this is the first time that a T-cell engager
has been seen to reactivate a CAR-T therapy, and the evidence
suggests that this reactivation drove a second wave of CAR-T cell
proliferation that led to another complete response three years
after the initial successful CAR-T treatment. This patient is now
off all anti-myeloma treatments and living in remission for more
than nine months following 1 week of TCE therapy, a truly
amazing outcome."
"These patient clinical data demonstrate the power of
TSCM CAR-T cells, which are a core element of all our
investigational next-generation, off-the-shelf allogeneic CAR-T
cell therapies," said Syed Rizvi,
M.D., Chief Medical Officer of Poseida Therapeutics. "P-BCMA-101
demonstrated durable persistence due to the high TSCM
content in the final product. This long-term persistence and
engraftment led to activation by the TCE several years after
initial CAR-T therapy. The high TSCM content and durable
persistence is a unique feature of all autologous and allogeneic
Poseida CAR-T."
Background Information and Oral Presentation
Highlights
Patients with relapsed/refractory multiple
myeloma who receive BCMA-directed CAR-T therapy can achieve deep
and durable remissions, but most patients relapse. Detection of
CAR-positive cells wanes rapidly over the first six months, and
significant re-expansion of CAR-T cells has not been demonstrated
previously in the clinical setting.
In this case study, a 57-year-old female patient with relapsed
multiple myeloma received P-BCMA-101, an investigational
TSCM-rich autologous CAR-T therapy. TSCM
cells are a subset of T cells that have unique properties: They are
long-lived, multi-potent and self-replicating and can engraft and
create differentiated cells.
Two months after receiving treatment, the patient achieved a
partial response that deepened into a stringent complete response
and remained in remission for nearly 2 years (22.5 months). More
than three years after receiving P-BCMA-101, she relapsed and was
treated with one cycle of talquetamab, a T-cell engaging bispecific
antibody that targets CD3 and GPRC5D. Upon receiving talquetamab,
the patient developed a brisk lymphocytosis. Evaluation of
peripheral blood revealed high levels of P-BCMA-101 CAR-T cells.
Thorough molecular analysis revealed that the lymphocytosis was
benign and reactive. The patient achieved complete remission with
slow resolution of lymphocytosis. The patient continues to be in
sCR and off all therapy more than nine months after receiving the
last and only full dose of the T-cell engaging therapy.
Poseida's lead investigational allogeneic CAR-T program,
P-BCMA-ALLO1, is currently being evaluated in patients with
relapsed/refractory multiple myeloma. The Company will report new
clinical data at the International Myeloma Society 21st Annual
Meeting, which is being held in Rio de
Janeiro from September 25-28,
2024. Additional P-BCMA-ALLO1 clinical updates are planned
for the second half of 2024, subject to coordination with Roche,
which has a strategic collaboration with Poseida covering multiple
investigational allogeneic CAR-T therapies targeting blood cancers,
including P-BCMA-ALLO1.
In November 2022, Poseida made the
strategic decision to transition its cell therapy focus from an
autologous to an allogeneic approach. The Company believes the
future of cell therapy and its ability to offer new treatment
options lies in an allogeneic approach in which T cells are derived
from healthy donors rather than from the patients themselves.
Poseida has applied learnings from its autologous programs to
support the development of its allogeneic pipeline.
About P-BCMA-ALLO1
P-BCMA-ALLO1 is an investigational allogeneic CAR-T therapy
licensed to Roche that targets B-cell maturation antigen (BCMA) for
the treatment of patients with relapsed/refractory multiple
myeloma. This allogeneic program includes a VH-based binder that
targets BCMA. Phase 1 clinical data presented at ASH 2023 supports
the Company's belief that TSCM-rich allogeneic CAR-Ts
have the potential to offer an effective, safe and reliable
treatment addressing unmet needs in multiple myeloma. The U.S.
Food and Drug Administration granted Orphan Drug Designation
to P-BCMA-ALLO1 for the treatment of multiple myeloma. Additional
information about the Phase 1 study is available
at www.clinicaltrials.gov (NCT04960579).
About Poseida Therapeutics, Inc.
Poseida Therapeutics
is a clinical-stage biopharmaceutical company advancing
differentiated allogeneic cell therapies and genetic medicines with
the capacity to cure certain cancers and rare diseases. The
Company's pipeline includes investigational allogeneic CAR-T cell
therapies for both solid tumors and hematologic cancers as well as
investigational in vivo genetic medicines that address patient
populations with high unmet medical need. The Company's approach is
based on its proprietary genetic editing platforms, including its
non-viral piggyBac® DNA Delivery System, Cas-CLOVER™ Site-Specific
Gene Editing System, Booster Molecule and nanoparticle gene
delivery technologies, as well as in-house GMP cell therapy
manufacturing. The Company has formed strategic collaborations with
Roche and Astellas to unlock the promise of cell therapies for
cancer patients. Learn more at www.poseida.com and
connect with Poseida on X and LinkedIn.
Forward-Looking Statements
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, expected plans with respect to clinical trials,
including timing of regulatory submissions and approvals and
clinical data updates; anticipated timelines and milestones with
respect to the Company's development programs and manufacturing
activities and capabilities; the potential capabilities and
benefits of the Company's technology platforms and product
candidates, including the efficacy, safety and reliability profile
of such product candidates; the quotes from Drs.
Martin and Rizvi; and the Company's plans and strategy
with respect to developing its technologies and product candidates.
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 the Company'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,
the Company's reliance on third parties for various aspects of its
business; risks and uncertainties associated with development and
regulatory approval of novel product candidates in the
biopharmaceutical industry; the Company's ability to retain key
scientific or management personnel; and the other risks described
in the Company's filings with the Securities and Exchange
Commission. All forward-looking statements contained in this press
release speak only as of the date on which they were made. The
Company 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.
