Combination of masofaniten plus enzalutamide
continues to be well tolerated with durable reductions in PSA in
patients with mCRPC
Phase 2 dose expansion currently underway at
the RP2CDs of masofaniten 600 mg BID in combination with
enzalutamide 160 mg QD
Across all dosing cohorts, 88% of patients
achieved PSA90, 69% of patients achieved PSA90 in less than 90
days, and 63% of patients achieved PSA <0.2ng/mL. After 15.2
months of follow up, median time to PSA progression and
radiographic progression free survival have not yet been
reached.
SOUTH
SAN FRANCISCO, Calif. and VANCOUVER, BC, Sept. 13,
2024 /PRNewswire/ - 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 2024 European
Society for Medical Oncology (ESMO) Congress, taking place
September 13-17, 2024, in
Barcelona, 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 "Publications" section
of the Company's website at www.essapharma.com.
"We are pleased to be sharing more mature data from the Phase 1
dose escalation study evaluating masofaniten in combination with
enzalutamide today at ESMO 2024. The combination continues to be
well tolerated with prolonged reductions in circulating
prostate-specific antigen ("PSA") levels in patients with
metastatic castration-resistant prostate cancer ("mCRPC"). After
15.2 months of follow up, neither median time to PSA progression
nor radiographic progression free survival have been reached. These
data compare favorably to historical data for single agent
enzalutamide treatment in the mCRPC patient population," said
David Parkinson, MD, President and
CEO of ESSA. "We continue to focus on the enrollment of the Phase 2
dose expansion study evaluating masofaniten in combination with
enzalutamide, with 33 sites activated in the
US, Canada and Australia and an additional 22
sites anticipated in Europe. We look forward to providing
further updates in 2025."
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): Phase 1 results and Phase 2 design
Presenting Author: Christos Kyriakopoulos, MD,
University of Wisconsin-Madison Carbone
Cancer Center
Presentation #: 1641P
Date and time: Sunday, September 15,
2024; 12:00-1:30 p.m. CEST/
6:00-7:30 a.m. ET
Data summary: This Phase 1/2 multicenter, open-label
clinical trial enrolled 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 includes 18 patients
across four cohorts 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 dose
levels tested through 32 cycles of dosing in some patients. Most
frequent adverse events were Grades 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, resulting in the expansion of the
cohort from four to seven patients. No additional dose-limiting
toxicities (DLTs) were observed, therefore the maximum tolerated
dose (MTD) was not reached. The recommended Phase 2 combination
doses (RP2CDs) were identified as masofaniten 600 mg twice daily
(BID) in combination with enzalutamide 160 mg once daily (QD).
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). Across all dose cohorts,
88% of patients (14 of 16) achieved PSA50, 88% of patients (14 of
16) achieved PSA90, 69% of patients (11 of 16) achieved PSA90 in
less than 90 days, and 63% of patients (10 of 16) achieved PSA
<0.2ng/mL. With a current median follow up of 15.2 months, the
median time to PSA progression and radiographic progression free
survival have not yet been reached.
The randomized, open-label, two arm, Phase 2 dose expansion
portion of the study is underway and is designed to evaluate the
combination of masofaniten and enzalutamide versus single agent
enzalutamide in patients with mCRPC naïve to second generation
anti-androgens. The study is currently enrolling at approximately
33 sites in the USA, Canada and Australia, and an additional 22 sites
anticipated in Europe.
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 X and LinkedIn.
Forward-Looking Statement Disclaimer
This release contains certain information which, as presented,
constitutes "forward-looking statements" within the meaning of the
Private Securities Litigation Reform Act of 1995 and
"forward-looking information" within the meaning of Canadian
securities laws (collectively, "forward-looking statements").
Forward-looking statements include, but are not limited to,
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, the
tolerability of masofaniten in combination with enzalutamide, PSA
reductions resulting from masofaniten in combination with
enzalutamide, the potential long-term benefits of
masofaniten, providing future updates on the Phase 1/2 and Phase 2
studies, the timing of and enrollment in the Company's studies and
other statements surrounding the Company's evaluation of
masofaniten.
Forward-looking statements 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 statements are 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 12, 2023, 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.
Contacts
ESSA Pharma, Inc.
Peter Virsik, Chief Operating
Officer
778.331.0962
pvirsik@essapharma.com
Investors and Media:
Argot Partners
212.600.1902
essa@argotpartners.com
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