Combination of masofaniten plus enzalutamide
continues to be well tolerated with deep and durable reductions in
PSA in patients with mCRPC
Across all cohorts of patients including those
recently enrolled into cohort four, 69% of patients achieved PSA90,
63% of patients achieved PSA90 in less than 90 days, and 56% of
patients achieved PSA <0.2mg/mL
SOUTH
SAN FRANCISCO, Calif. and VANCOUVER, Canada, Oct. 21,
2023 /CNW/ - ESSA Pharma Inc. ("ESSA", or the
"Company") (NASDAQ: EPIX), a clinical-stage pharmaceutical company
focused on developing novel therapies for the treatment of prostate
cancer, today announced the presentation of updated dose escalation
data from its Phase 1/2 study evaluating
masofaniten (formerly EPI-7386) in combination with enzalutamide at
the European Society of Medical Oncology (ESMO) 2023 Congress,
taking place October 20-24, 2023, in
Madrid, Spain. Masofaniten is a
first-in-class N-terminal domain androgen receptor ("AR") inhibitor
that suppresses androgen activity through a novel mechanism of
action and is being developed for the treatment of prostate cancer.
The poster presentation is available on the ESMO Digital
Program and in the "Publications" section of the Company's
website at www.essapharma.com.
"The dose escalation data presented at ESMO this year continue
to demonstrate that the combination of masofaniten and enzalutamide
is well tolerated and results in deep and durable reductions in
prostrate-specific antigen ("PSA") in patients with metastatic
castration-resistant prostate cancer ("mCRPC")," said David Parkinson, MD, President and CEO of ESSA.
"While the data for patients in cohort four are not yet mature, we
are highly encouraged by the PSA responses seen thus far in the
cohort and in the study as a whole. We look forward to further
elucidating the potential clinical benefit of this combination in
the randomized Phase 2 portion of the study which
is currently underway."
Poster presentation details:
Title: Phase 1/2 Trial of Oral EPI-7386
(masofaniten) in Combination with Enzalutamide (Enz) Compared with
Enz Alone in Subjects with Metastatic Castration-Resistant Prostate
Cancer (mCRPC): Current Phase 1 (P1) results
Presenting Author: Andrew Laccetti, MD, MS, Memorial
Sloan Kettering Cancer Center
Abstract # 1813P
Date: Sunday, October 22, 2023
Data summary: This Phase 1/2 multicenter, open-label
clinical trial is enrolling patients with mCRPC who have received
androgen deprivation therapy and who are naïve to second-generation
antiandrogens but may have been treated previously with one line of
prior chemotherapy in the metastatic hormone-sensitive prostate
cancer setting. The data presented today are from the first four
cohorts of patients in the Phase 1 dose
escalation portion of the study. Masofaniten has no effect on
enzalutamide exposure, thus allowing the use of full dose per label
(160mg) of enzalutamide in combination. Enzalutamide reduces
masofaniten exposure but twice daily dosing of masofaniten appears
to mitigate the reduction and maintains clinically relevant drug
exposures.
In patients evaluable for safety (n=18), masofaniten combined
with enzalutamide, continues to be well-tolerated at the doses
tested through 21 cycles of dosing in some patients. Most frequent
adverse events were Grade 1 and 2, related to
either AR inhibition or gastrointestinal tract irritation. In
Cohort 4, one patient experienced a Grade 3 rash,
which was observed immediately following administration of
masofaniten combined with enzalutamide and deemed probably
related.
In the patients evaluable for efficacy (n=16), rapid, deep and
durable reductions in PSA were observed, regardless of previous
chemotherapy status, including in patients who received lower than
the full dose of enzalutamide (120 mg). In the first three cohorts,
90% of patients (9 of 10) achieved PSA50 and PSA90, 80% of patients
(8 of 10) achieved PSA90 in less than 90 days, and 70% of patients
(7 of 10) achieved PSA <0.2mg/mL. Across all dose cohorts
including patients in the recently enrolled cohort four, 88% of
patients (14 of 16) achieved PSA50, 69% of patients (11 of 16)
achieved PSA90, 63% of patients (10 of 16) achieved PSA90 in less
than 90 days, and 56% of patients (9 of 16) achieved PSA
<0.2mg/mL. The randomized Phase 2 dose
expansion portion of the study is currently enrolling.
About Masofaniten
Masofaniten (formerly known as EPI-7386) is a first-in-class
investigational, highly selective, oral, small molecule inhibitor
of the N-terminal domain ("NTD") of the androgen receptor ("AR").
Masofaniten's unique mechanism of action disrupts the AR signaling
pathway, the primary pathway that drives prostate cancer growth, by
selectively binding to the NTD, a region of the AR that is not
currently targeted by other therapies. Masofaniten is currently
being studied in an open-label, randomized
Phase 2 clinical trial (NCT05075577) in
combination with enzalutamide in patients with metastatic
castration-resistant prostate cancer (mCRPC) naïve to
second-generation antiandrogens. ESSA is also conducting a Phase 1
monotherapy study (NCT04421222) in patients with mCRPC whose tumors
have progressed on standard-of-care therapies. The U.S. Food and
Drug Administration has granted Fast Track designation to
masofaniten for the treatment of adult male patients with mCRPC
resistant to standard-of-care treatment. ESSA retains all rights to
masofaniten worldwide.
About ESSA Pharma Inc.
ESSA is a clinical-stage pharmaceutical company focused on
developing novel and proprietary therapies for the treatment of
patients with prostate cancer. For more information, please
visit www.essapharma.com, and follow us on Twitter and
LinkedIn.
Forward-Looking Statement
Disclaimer
This release contains certain information which, as presented,
constitutes "forward-looking information" within the meaning of the
Private Securities Litigation Reform Act of 1995 and/or applicable
Canadian securities laws. Forward-looking information involves
statements that relate to future events and often addresses
expected future business and financial performance, containing
words such as "anticipate", "believe", "plan", "estimate",
"expect", and "intend", statements that an action or event "may",
"might", "could", "should", or "will" be taken or occur, or other
similar expressions and includes, but is not limited to, statements
regarding presentations with respect to the Phase 1/2 study,
tolerability and PSA reductions in patients with mCRPC, the
potential clinical benefit of the combination of masofaniten and
enzalutamide, the timing of and enrollment in the Phase 2 portion
of the combination study and other statements surrounding the
Company's evaluation of masofaniten.
Forward-looking statements and information are subject to
various known and unknown risks and uncertainties, many of which
are beyond the ability of ESSA to control or predict, and which may
cause ESSA's actual results, performance or achievements to be
materially different from those expressed or implied thereby. Such
statements reflect ESSA's current views with respect to future
events, are subject to risks and uncertainties and are necessarily
based upon a number of estimates and assumptions that, while
considered reasonable by ESSA as of the date of such statements,
are inherently subject to significant medical, scientific,
business, economic, competitive, political and social uncertainties
and contingencies. In making forward looking statements, ESSA may
make various material assumptions, including but not limited to (i)
the accuracy of ESSA's financial projections; (ii) obtaining
positive results of clinical trials; (iii) obtaining necessary
regulatory approvals; and (iv) general business, market and
economic conditions.
Forward-looking information is developed based on assumptions
about such risks, uncertainties and other factors set out herein
and in ESSA's Annual Report on Form 10-K dated December 13, 2022, under the heading "Risk
Factors", a copy of which is available on ESSA's profile on EDGAR
at www.sec.gov and on SEDAR+ at www.sedarplus.ca, and as otherwise
disclosed from time to time on ESSA's EDGAR and SEDAR+ profiles.
Forward-looking statements are made based on management's beliefs,
estimates and opinions on the date that statements are made and
ESSA undertakes no obligation to update forward-looking statements
if these beliefs, estimates and opinions or other circumstances
should change, except as may be required by applicable United States and Canadian securities laws.
Readers are cautioned against attributing undue certainty to
forward-looking statements.
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