Sutro Biopharma, Inc. (Sutro or the Company) (NASDAQ: STRO), a
clinical-stage oncology company pioneering site-specific and
novel-format antibody drug conjugates (ADCs), today announced that
its research collaborators presented data on anti-leukemic activity
from the compassionate use of luveltamab tazevibulin (luvelta), a
novel folate receptor-α (FR-α) targeting ADC, in pediatric patients
with relapsed/refractory CBFA2T3-GLIS2 (CBF/GLIS) acute myeloid
leukemia (AML), commonly known as RAM phenotype AML. Data
demonstrated that treatment with luvelta produced meaningful
clinical responses, including complete remission (CR); and prolongs
overall survival (OS) enabling some patients to receive potentially
curative therapies such as hematopoietic stem cell transplant.
These patients were treated under the single patient IND mechanism.
These data were featured in a poster presentation at the 65th
American Society of Hematology Annual Meeting and Exposition (ASH
2023) in San Diego, CA.
“Treatment with luvelta led to notable response in a significant
subset of patients who had exhausted all therapeutic options,” said
Soheil Meshinchi, M.D., Ph.D., presenter and primary author.
“Response varied from deep remissions to disease stabilization with
minimal toxicity – mostly in outpatient setting. Luvelta was
well tolerated as long-term maintenance therapy with little to no
hematopoietic toxicity.”
CBF/GLIS subtype AML is a rare and highly lethal form of
leukemia found exclusively in infants and young children, with the
average age of onset at 18 months 1. There are no therapies
specifically approved to target this form of leukemia and it is
resistant to conventional chemotherapy, with an induction failure
rate of over 80%2. Due to a lack of effective treatment, children
diagnosed with the disease have a dismal two-year survival rate of
15%3. Recent studies have shown that FOLR1, which encodes for
FolRα, is silent in normal hematopoiesis, but is uniquely induced
by the CBF/GLIS fusion4.
Under compassionate use, 25 pediatric patients with
relapsed/refractory CBF/GLIS subtype AML were treated with luvelta
at doses up to 4.3 or 5.2mg/kg every two to four weeks for a median
duration of 15.9 weeks (3-73.1), with the majority of patients
receiving at least five doses (68%). Of the 25 treated patients, 19
had ≥5% blasts (morphologic disease, or MD) and 8 had <5% blasts
(sub-morphologic disease, or SMD)5. Collective results show that
treatment with luvelta produced clinically meaningful and durable
responses across a broad range of patients in various settings
including in patients with or without prior stem cell transplant
and in monotherapy or in combination with cytotoxic therapy. These
data were generated by the treating physicians and collected and
enabled for presentation by Sutro.
“It is clear from these data that luvelta is providing an
ongoing and promising impact on the lives of infants and young
children with this rare leukemia,” said Bill Newell, Sutro’s Chief
Executive Officer. “These results add to the growing body of
research supporting the development of luvelta, which has now seen
positive clinical results across three different tumor types,
including those with potentially low or variable folate receptor-α
expression.”
ASH Presentation Highlights:
- Overall, anti-leukemic activity was seen with luvelta either as
a single agent or in combination.
- 19 patients had ≥5% blasts and 8 patients had <5% blasts5.
- A CR/CRh was observed in 8 out of 19 (42%) patients with ≥5%
blasts treated with luvelta, with 5 out of 8 CR/CRh patients
reaching a minimal residual disease (MRD)-negative CR (63%).
- 6 out of 8 patients with <5% blasts experienced an
MRD-negative CR (75%).
- Patients whose leukemia experienced an MRD-negative CR had an
improved outcome over those who did not experience an MRD-negative
CR.
- Treatment with luvelta also enabled some children to bridge to
stem cell transplant, which is potentially curative therapy.
- Luvelta was well-tolerated as a monotherapy agent and in
combination with standard of care therapies with minimal
hematopoietic toxicity and can be delivered as outpatient
therapy.
- As of September 17, 2023, 8 patients remain on treatment, with
5 of the 8 (63%) in continued remission and on luvelta
maintenance.
The poster titled, “Anti-leukemic Activity of Luveltamab
Tazevibulin (LT, STRO-002), a Novel Folate Receptor-α
(FR-α)-targeting Antibody Drug Conjugate (ADC) in
Relapsed/Refractory CBFA2T3::GLIS2 AML,” will be accessible
through the News & Events page of the Investor Relations
section of the company’s website at www.sutrobio.com.
*1: National Institutes of Health [NIH], 2022; Quessada et al
2021; Masseti et al 2019*2: Smith JL, et al. Comprehensive
Transcriptome Profiling of Cryptic CBFA2T3-GLIS2 Fusion-Positive
AML Defines Novel Therapeutic Options: A COG and TARGET Pediatric
AML Study. Clin Cancer Res. 2020 Feb 1;26(3):726-737. doi:
10.1158/1078-0432.CCR-19-1800. Epub 2019 Nov 12. PMID: 31719049;
PMCID: PMC7002196.*3: Tang T, et al. Targeting FOLR1 in high-risk
CBF2AT3-GLIS2 pediatric AML with STRO-002 FOLR1-antibody-drug
conjugate, Blood Adv. 2022 Nov 22;6(22):5933-5937. doi:
10.1182/bloodadvances.2022008503. PMID: 36149945; PMCID:
PMC9701621. *4: Le Q, et al. Targeting FOLR1 in High-Risk
CBFA2T3-GLIS2 AML with Stro-002 FOLR1-Directed Antibody-Drug
Conjugate, Blood, Volume 138, Supplement 1, 2021, Page 209, ISSN
0006-4971, https://doi.org/10.1182/blood-2021-153076.*5: Two
patients initially presented with <5% blasts, received luvelta
and proceeded to BMT. Both relapsed post-transplant with ≥5% blasts
and re-started luvelta.
About Luveltamab TazevibulinLuveltamab
tazevibulin, abbreviated as “luvelta” and formerly known as
STRO-002, is a FolRα-targeting antibody-drug conjugate (ADC)
designed to treat a broad range of patients with ovarian cancer,
including those with lower FolRα-expression who are not eligible
for approved treatment options targeting FolRα. Developed and
manufactured with Sutro’s cell-free XpressCF® platform, luvelta is
a homogeneous ADC with four hemiasterlin cytotoxins per antibody,
precisely positioned to efficiently deliver to the tumor while
ensuring systemic stability after dosing. Sutro recently initiated
REFRaME, a Phase 2/3 registration-directed study for patients with
platinum-resistant ovarian cancer. The company has ongoing trials
in patients with endometrial cancer and in combination with
bevacizumab in patients with ovarian cancer. The company is also
assessing the clinical path forward for CBF/GLIS2 acute myeloid
leukemia, a rare subtype of pediatric cancer, as well as non-small
cell lung cancer. The U.S. Food and Drug Administration (FDA) has
granted luvelta a Fast Track designation for Ovarian Cancer, as
well as Orphan and Rare Pediatric Disease designations for
CBF/GLIS2 Pediatric AML.
About Sutro
Biopharma Sutro Biopharma, Inc., is a
clinical-stage company relentlessly focused on the discovery and
development of precisely designed cancer therapeutics, transforming
what science can do for patients. Sutro’s fit-for-purpose
technology, including cell-free XpressCF®, provides the opportunity
for broader patient benefit and an improved patient experience.
Sutro has multiple clinical stage candidates, including luveltamab
tazevibulin, or luvelta, a registrational-stage folate receptor
alpha (FolRα)-targeting ADC in clinical studies. A robust pipeline,
coupled with high-value collaborations and industry partnerships,
validates Sutro’s continuous product innovation. Sutro is
headquartered in South San Francisco. For more information, follow
Sutro on social media @Sutrobio, or visit
www.sutrobio.com.
Forward-Looking StatementsThis
press release contains forward-looking statements within the
meaning of the “safe harbor” provisions of the Private Securities
Litigation Reform Act of 1995, including, but not limited to,
anticipated preclinical and clinical development activities, timing
of announcements of clinical results, trial initiation, and
regulatory filings, potential benefits of luvelta and the Company’s
other product candidates and platform, potential future milestone
and royalty payments, the Company’s expectations about its cash
runway, and potential market opportunities for luvelta and the
Company’s other product candidates. All statements other than
statements of historical fact are statements that could be deemed
forward-looking statements. Although the Company believes that the
expectations reflected in such forward-looking statements are
reasonable, the Company cannot guarantee future events, results,
actions, levels of activity, performance or achievements, and the
timing and results of biotechnology development and potential
regulatory approval is inherently uncertain. Forward-looking
statements are subject to risks and uncertainties that may cause
the Company’s actual activities or results to differ significantly
from those expressed in any forward-looking statement, including
risks and uncertainties related to the Company’s ability to advance
its product candidates, the receipt and timing of potential
regulatory designations, approvals and commercialization of product
candidates and the Company’s ability to successfully leverage Fast
Track designation, the market size for the Company’s product
candidates to be smaller than anticipated, clinical trial sites,
supply chain and manufacturing facilities, the Company’s ability to
maintain and recognize the benefits of certain designations
received by product candidates, the timing and results of
preclinical and clinical trials, the Company’s ability to fund
development activities and achieve development goals, the Company’s
ability to protect intellectual property, the value of the
Company’s holdings of Vaxcyte common stock, and the Company’s
commercial collaborations with third parties and other risks and
uncertainties described under the heading “Risk Factors” in
documents the Company files from time to time with the Securities
and Exchange Commission. These forward-looking statements speak
only as of the date of this press release, and the Company
undertakes no obligation to revise or update any forward-looking
statements to reflect events or circumstances after the date
hereof.
ContactEmily WhiteSutro Biopharma (650)
823-7681ewhite@sutrobio.com
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