Shattuck Labs Announces Positive Initial Topline Data from Ongoing Phase 1 A/B Dose Expansion Clinical Trial of SL-172154 with Azacitidine in Frontline Higher-Risk Myelodysplastic Syndromes (HR-MDS) and TP53 mutant (TP53m) Acute Myeloid Leukemia (AML) Pati
13 December 2023 - 10:00PM
Shattuck Labs, Inc. (Shattuck) (NASDAQ: STTK), a clinical-stage
biotechnology company pioneering the development of bi-functional
fusion proteins as a new class of biologic medicine for the
treatment of patients with cancer and autoimmune disease, today
announced initial topline dose-expansion data from its ongoing
Phase 1A/B clinical trial of SL-172154 in combination with AZA in
frontline HR-MDS and TP53m AML patients. Initial data from the
dose-expansion cohorts build on the complete dose-escalation data
featured in a poster presentation on December 11, 2023 at the 65th
ASH Annual Meeting.
“Both the frontline HR-MDS and TP53m AML expansion cohorts
enrolled quickly after completion of the dose escalation study in
the middle of this year, and we are pleased to share initial
efficacy data, which begin to demonstrate the activity of SL-172154
beyond what is expected of AZA alone. In dose escalation, we saw a
monotherapy response to SL-172154 in a heavily pre-treated
relapsed/refractory (R/R) TP53m AML patient that allowed the
patient to receive a stem cell transplant. That patient remains
disease free.” said Dr. Lini Pandite, MBChB, M.B.A., Chief Medical
Officer of Shattuck. “In frontline, the rate of complete responses
in both the HR-MDS and TP53m AML cohorts is already encouraging,
and when coupled with the observation of peripheral blood count
recovery in most patients that have not yet achieved a complete
response, and the fact that many of these patients are very early
in their course of treatment and have not yet reached the median
time at which a complete response is expected for azacitidine,
suggests that the complete response rate may continue to improve in
the coming months. As a result, we have amended both studies to
increase the sample size and look forward to providing another
update by mid-year 2024.”
Phase 1B Trial of SL-172154 in Frontline TP53m AML and
HR-MDSKey takeaways: Early efficacy
observed for SL-172154 in combination with AZA in previously
untreated HR-MDS and TP53m AML:
- HR-MDS: In 14 evaluable patients with
previously untreated HR-MDS (13 of whom had TP53m or deletion),
five patients achieved a CR. Four patients achieved a mCR (3 with
hematologic improvement in at least one lineage), and two patients
achieved stable disease (both with hematologic improvement in at
least one lineage).
- TP53m AML: In 11 evaluable patients with
previously untreated TP53m AML, two patients achieved a CR. Another
patient achieved a CRi and was taken to allogeneic hematopoietic
cell transplantation (allo-HCT). Seven additional subjects with
stable disease had blast reductions, five of which had recovery of
platelets or neutrophils and remain on study and their response may
improve. One subject died during the first cycle.
- Safety: Preliminary data suggest that
SL-172154 has an acceptable safety and tolerability profile in
combination with azacitidine.
- Data Overview: As of the data cut-off date of
December 1, 2023, 14 frontline patients enrolled in the TP53m AML
cohort, and 22 frontline patients enrolled in the HR-MDS cohort.
Initial enrollment was completed in the fourth quarter of 2023 and
Shattuck has elected to expand the cohorts with additional data
expected mid-year 2024.
- Preliminary signs of anti-tumor activity:
Early signals of activity, in the form of rapid blast count
reductions, were observed in 100% of frontline TP53m AML patients
treated with SL-172154 in combination with AZA who received an
on-treatment bone marrow biopsy. Most patients in the HR-MDS cohort
showed blast count reductions with hematologic improvement early in
the treatment course.
- SL-172154 had an acceptable safety and tolerability
profile: Infusion-related reactions (IRRs) were the most
common SL-172154 related treatment-emergent adverse events (TEAEs).
- In the TP53m AML and HR-MDS cohorts, IRRs were reported in
seven patients (50%) and seven patients (32%) respectively.
- Grade 3 or 4 AEs related to SL-172154 were reported in two
patients (14%) in TP53m AML and four patient (18%) in HR-MDS,
including IRR (2), increased AST (1), increased ALT (1), fatigue
(1), hypoxia (1), pneumonia (1), chondrocalcinosis (1), and febrile
neutropenia (1). There were no reports of destructive anemia.
- In the TP35m AML expansion cohort, there was one Grade 5 AE of
cardiac arrest reported in one patient with history of coronary
artery disease, recent arrhythmia, and hypokalemia in the
setting of amiodarone use. In the HR-MDS cohort, there were no
Grade 5 AEs related to SL-172154 reported.
Phase 1A Trial of SL-172154 in R/R AML and HR-MDS and
Frontline TP53m HR-MDSA copy of the ASH presentation,
titled “Safety, Pharmacodynamic, and Anti-Tumor Activity of
SL-172154 as Monotherapy and in Combination with Azacitidine (AZA)
in Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML) and
Higher-Risk Myelodysplastic Syndromes/neoplasms (HR-MDS) Patients
(pts),” is accessible under posters in the “Our Science” section of
Shattuck’s website.
Key takeaways: Anti-tumor responses were observed as monotherapy
and in combination with AZA. SL-172154 alone and in combination
with AZA had an acceptable safety profile, consistent with the
safety profile of the individual agents (see SL-172154 safety
above). No destructive anemia was observed.
- Data Overview: As of the data cut-off date of
September 15, 2023, 32 adult patients with R/R AML and HR-MDS
received SL-172154 as monotherapy or in combination with AZA in the
parallel staggered dose-escalation portion of a Phase 1A/B clinical
trial. Patients had a median of two prior lines of therapy. An
additional five subjects with frontline TP53m HR-MDS received
SL-172154 with AZA.
- Preliminary signs of anti-tumor activity:
Monotherapy response in a R/R AML patient and early signals of
anti-leukemic activity (in the form of blast count reductions) in
patients with R/R AML who received SL-172154 in combination with
AZA were observed in a dose-dependent manner.
- SL-172154 monotherapy activity (Morphologic Leukemia-Free
State) was observed in a heavily pretreated R/R AML patient and
subsequently proceeded to allo-HCT.
- Patient achieved MLFS (blast reduction from 19% to <5%)
after one cycle of SL-172154.
- Anti-tumor activity was also observed in combination with AZA
in previously untreated TP53m HR-MDS patients. Out of four
evaluable previously untreated TP53m HR-MDS patients, there was one
CR and one mCR. One patient with mCR and one patient with SD
proceeded to allo-HCT. The patient in a CR remains in a CR long
term.
Conference Call at 8:00 a.m. ET TodayShattuck
will host a conference call today at 8:00 a.m. ET featuring key
opinion leader Dr. Naval Daver, MD, (Professor, Director Leukemia
Research Alliance Program, Department of Leukemia, The University
of Texas MD Anderson Cancer Center, Houston, TX) to present the
initial data from the frontline expansion cohorts in HR-MDS and
TP53m AML. Additionally, a review of data from the poster
presentation featured at the 65th ASH Annual Meeting will be
discussed. To listen to the live webcast, please visit the Investor
Relations page of the Shattuck Labs website here. Participants
may register for the call here. While not required, interested
participants are encouraged to join 10 minutes prior to the start
of the event.
A replay of the webcast will be available following the
conclusion of the live call and will be accessible on the Company’s
website.
About SL-172154SL-172154 (SIRPα-Fc-CD40L) is an
investigational ARC® fusion protein designed to simultaneously
inhibit the CD47/SIRPα checkpoint interaction and activate the CD40
costimulatory receptor to bolster an anti-tumor immune response in
patients with advanced cancer. Multiple Phase 1 clinical trials are
ongoing for patients with PROC (NCT04406623, NCT05483933) and
patients with AML and HR-MDS (NCT05275439).
About Shattuck Labs, Inc.Shattuck Labs, Inc.
(NASDAQ: STTK) is a clinical-stage biotechnology company pioneering
the development of bi-functional fusion proteins as a new class of
biologic medicine for the treatment of patients with cancer and
autoimmune disease. Compounds derived from Shattuck’s proprietary
Agonist Redirected Checkpoint, (“ARC®”), platform are designed to
simultaneously inhibit checkpoint molecules and activate
costimulatory molecules with a single therapeutic. The company’s
lead SL-172154 (SIRPα-Fc-CD40L) program, which is designed to block
the CD47 immune checkpoint and simultaneously agonize the CD40
pathway, is being evaluated in multiple Phase 1 trials. Shattuck
has offices in both Austin, Texas and Durham, North Carolina. For
more information, please visit: www.ShattuckLabs.com.
Forward-Looking StatementsCertain statements in
this press release may constitute “forward-looking statements”
within the meaning of the federal securities laws, including, but
not limited to, the clinical benefit of SL-172154 in frontline
HR-MDS and TP53m AML patients, the safety and tolerability profile
of SL-172154, and the anticipated timing of additional data from
our clinical trials. Words such as “may,” “might,” “will,”
“objective,” “intend,” “should,” “could,” “can,” “would,” “expect,”
“believe,” “design,” “estimate,” “predict,” “potential,” “develop,”
“plan” or the negative of these terms, and similar expressions, or
statements regarding intent, belief, or current expectations, are
forward-looking statements. While we believe these forward-looking
statements are reasonable, undue reliance should not be placed on
any such forward-looking statements, which are based on information
available to us on the date of this release. These forward-looking
statements are based upon current estimates and assumptions and are
subject to various risks and uncertainties (including, without
limitation, those set forth in our filings with the U.S. Securities
and Exchange Commission (the “SEC”)), many of which are beyond our
control and subject to change. Actual results could be materially
different. Risks and uncertainties include: global macroeconomic
conditions and related volatility, expectations regarding the
initiation, progress, and expected results of our preclinical
studies, clinical trials and research and development programs;
expectations regarding the timing, completion and outcome of our
clinical trials; the unpredictable relationship between preclinical
study results and clinical study results; the timing or likelihood
of regulatory filings and approvals; liquidity and capital
resources; and other risks and uncertainties identified in our
Annual Report on Form 10-K for the year ended December 31, 2022,
and subsequent disclosure documents filed with the SEC. We claim
the protection of the Safe Harbor contained in the Private
Securities Litigation Reform Act of 1995 for forward-looking
statements. We expressly disclaim any obligation to update or alter
any statements whether as a result of new information, future
events or otherwise, except as required by law.
The Company intends to use the investor relations portion of its
website as a means of disclosing material non-public information
and for complying with disclosure obligations under Regulation
FD.
Investor & Media Contact: Conor
RichardsonVice President of Investor RelationsShattuck Labs,
Inc.InvestorRelations@shattucklabs.com
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