RCS - PureTech Health PLC - PRTC's Gallop: Positive Initial Topline AML Data

Puretech HealthAnnouncement

05/12/2025 18:00

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RNS Number : 5178K  PureTech Health PLC  05 December 2025

5 December 2025

PureTech Health plc

 

PureTech's Founded Entity Gallop Oncology Announces Positive Initial Topline
Data from Phase 1b Trial of LYT-200 in Relapsed/Refractory Acute Myeloid
Leukemia and High-Risk Myelodysplastic Syndrome

 

LYT-200 demonstrated favorable tolerability and strong efficacy in a heavily
pretreated population, both in combination with standard of care and as a
monotherapy, supporting advancement toward a potentially registrational Phase
2 trial

 

Initial median overall survival of 13.2 months observed in the combination
cohort at the proposed Phase 2 dose, exceeding expected late-line
relapsed/refractory setting survival of <2.5 months; overall survival data
at this dose continue to mature with final results expected in 1H 2026

 

Responses observed in patients with high-risk mutations, suggesting potential
broad applicability

 

Further details to be shared at the 67th American Society of Hematology (ASH)
Annual Meeting

 

PureTech Health plc (https://puretechhealth.com/)  (Nasdaq: PRTC, LSE: PRTC)
("PureTech" or the "Company"), a hub-and-spoke biotherapeutics company
dedicated to giving life to science and transforming innovation into value,
notes that its Founded Entity, Gallop Oncology, today announced initial
topline results from the Phase 1b clinical trial evaluating LYT-200, a
first-in-class anti-galectin-9 monoclonal antibody, in patients with
relapsed/refractory acute myeloid leukemia (AML) and high-risk myelodysplastic
syndrome (MDS). The data demonstrated a favorable tolerability profile and
strong efficacy, supporting the advancement of LYT-200 into a potentially
registrational Phase 2 trial in AML. Additional details will be shared at the
67th American Society of Hematology (ASH) Annual Meeting on December 6(th),
2025.

 

"Patients with relapsed/refractory AML or high-risk MDS face extremely limited
treatment options, and overall survival at this stage is typically less than
2.5 months. With LYT-200, we have demonstrated durable responses, enabled a
substantially meaningful proportion of patients to proceed to transplant, and
shown initial median overall survival data of 13.2 months at the proposed
Phase 2 dose - all alongside a very favorable safety profile. Together, these
findings represent a potential step change in the treatment of AML," said Luba
Greenwood, JD, Chief Executive Officer of Gallop Oncology. "Importantly, these
compelling results were observed in patients across several high-risk
mutations, underscoring the central role of galectin-9 in driving this disease
as well as the potential broad applicability of LYT-200 in AML and beyond. The
strength of the data gives us confidence as we advance toward a potentially
registrational Phase 2 study in AML and supports future evaluation of LYT-200
in earlier lines of treatment. We look forward to engaging with regulatory
authorities once the maturing overall survival data are finalized."

 

The Phase 1b, open-label, dose-escalation and dose-expansion trial evaluated
LYT-200 both in combination with the standard-of-care (SOC) regimen of
venetoclax (VEN) and a hypomethylating agent (HMA) and as a monotherapy in a
heavily pretreated patient population (median prior lines of treatment: 3;
range: 1-7).

 

TOPLINE SAFETY

LYT-200 demonstrated a favorable safety profile, with no LYT-200-related
serious adverse events or dose-limiting toxicities observed in the trial
(n=101). Importantly, no overlapping or additive toxicities were seen when
LYT-200 was combined with VEN/HMA.

 

INITIAL TOPLINE EFFICACY

Combination Cohorts

The majority of participants (87.5%) in the combination cohort had previously
been treated with VEN/HMA, and their disease had either returned or failed to
respond. Across all evaluable patients 1  treated with LYT-200 in combination
with VEN/HMA (n=43), robust antileukemic activity was demonstrated, with a
combined complete response (complete response + complete response with
incomplete hematological recovery) rate of 33%. Among those who achieved a
complete response, 50% proceeded to stem cell transplant. Responses were
observed in patients with diverse, high-risk mutations, including KRAS, NRAS,
JAK2, and KIT, underscoring LYT-200's mutation-agnostic mechanism of action
and potential for broad use.

 

At the proposed Phase 2 dose of 12 mg/kg (n=32 evaluable), treatment with
LYT-200 in combination with VEN/HMA demonstrated:

 * 38% combined complete response rate

 * 97% disease control rate

 * Initial median overall survival of 13.2 months, with data continuing to mature
into the first half of 2026

 

Monotherapy Cohorts

As a monotherapy (n=26 evaluable), LYT-200 demonstrated clinical activity and
disease stabilization in patients whose disease had progressed following
multiple prior lines of treatment, supporting the independent mechanism of
galectin-9 blockade as a single agent. Median overall survival in this cohort
was 6.5 months, and one partial response has been maintained for 27 months in
a patient whose disease previously progressed following five prior rounds of
treatment.

 

"For patients whose AML has progressed, survival is often measured in months,
and the toxicities of additional treatments frequently limit what we can
realistically offer. What stands out with the LYT-200 data is not only the
durable responses we have seen and the ability for some patients to proceed to
transplant, but that these outcomes were achieved with a highly favorable
tolerability profile," said Amir T. Fathi, MD, Program Director of the Center
for Leukemia at the Massachusetts General Hospital Cancer Center and Associate
Professor of Medicine at Harvard Medical School. "LYT-200 is not a targeted
therapy in the traditional sense; it targets galectin-9, a foundational driver
of leukemia biology. The significance of this approach is evidenced by the
activity observed across multiple high-risk mutations, suggesting LYT-200 may
be uniquely applicable across a broad patient population. Coupled with the
emerging overall survival signal at the proposed Phase 2 dose, these data
provide strong clinical rationale to advance LYT-200 into late-stage
development for the treatment of AML."

 

LYT-200 has been granted Fast Track and Orphan Drug designations from the U.S.
Food and Drug Administration (FDA) for the treatment of AML. Gallop intends to
engage with regulatory authorities to discuss the proposed Phase 2 dose and
potentially registrational path after the overall survival data have fully
matured. Final overall survival results are expected in the first half of
2026.

 

The poster shared at ASH 2025 will be made available on Gallop's website.

 

About AML

Acute myeloid leukemia (AML) is an aggressive blood cancer characterized by
the rapid growth of abnormal myeloid cells in the bone marrow and blood. It is
the most common form of acute leukemia in adults, with a five-year survival
rate of less than 30%. Despite available therapies, many patients relapse or
fail to respond, and outcomes are especially poor in the relapsed/refractory
setting. Around 450,000 people globally are living with AML.

 

AML is an area of urgent medical need where new therapies with improved
efficacy and durability are critical. Importantly, the incidence of AML is
increasing, and the market is expected to grow to $6 billion by 2030,
underscoring the scale of the opportunity to bring forward therapies that are
not only more effective but also applicable across a broader segment of
patients. 2 

 

About LYT-200

LYT-200 is a fully human IgG4 monoclonal antibody in development for the
treatment of hematological malignancies and solid tumors with otherwise poor
survival rates.

 

LYT-200's target, galectin-9, is a key oncogenic driver and potent
immunosuppressor in cancer. Blocking galectin-9 is believed to have a dual
mode of action, both killing tumor cells directly while also stimulating
anti-tumor immunity. Galectin-9 is the fundamental driver of the AML disease
process. AML stem cells have higher expression of galectin-9 than their
healthy counterparts, and higher expression is associated with treatment
failure.

 

LYT-200 has been granted Fast Track
(https://news.puretechhealth.com/news-releases/news-release-details/puretech-receives-fda-fast-track-designation-lyt-200-acute)
and Orphan Drug
(https://news.puretechhealth.com/news-releases/news-release-details/puretech-receives-orphan-drug-designation-lyt-200-acute-myeloid)
designations from the U.S. Food and Drug Administration (FDA) for the
treatment of acute myeloid leukemia, underscoring the high unmet need in this
disease and the potential for LYT-200 to serve as a meaningful therapeutic
option.

 

About Gallop Oncology

Gallop is a clinical-stage biopharmaceutical company committed to transforming
treatment paradigms for hematologic malignancies. Guided by science and driven
to deliver meaningful outcomes for patients, Gallop is advancing a novel
approach where efficacy, safety, and durability converge. Its lead candidate,
LYT-200, is the most advanced candidate targeting galectin-9, a key oncogenic
driver, offering a differentiated strategy to address some of the most
challenging cancers. LYT-200's lead indication is acute myeloid leukemia
(AML).

 

Gallop Oncology was founded by and is currently wholly-owned by PureTech
Health plc (Nasdaq: PRTC, LSE: PRTC), a hub-and-spoke biotherapeutics company
dedicated to giving life to science. PureTech's innovative R&D engine
powers Founded Entities like Gallop, advancing highly promising medicines to
patients in a capital-efficient manner. For more information, please visit
www.galloponcology.com (https://www.galloponcology.com) .

 

About PureTech Health

PureTech Health is a hub-and-spoke biotherapeutics company dedicated to giving
life to science and transforming innovation into value. We do this through a
proven, capital-efficient R&D model focused on opportunities with
validated pharmacology and untapped potential to address significant patient
needs. This strategy has produced dozens of therapeutic candidates, including
three that have received U.S. FDA approval. By identifying, shaping, and
de-risking these high-conviction assets, and scaling them through dedicated
structures backed by external capital, we accelerate their path to patients
while creating sustainable value for shareholders.

 

For more information, visit www.puretechhealth.com or connect with us on X
(formerly Twitter) @puretechh.

 

Cautionary Note Regarding Forward-Looking Statements

This press release contains statements that are or may be forward-looking
statements within the meaning of the Private Securities Litigation Reform Act
of 1995. All statements contained in this press release that do not relate to
matters of historical fact should be considered forward-looking statements,
including without limitation those related to the LYT-200 development program
and development plans, its potential benefits to patients, plans for
discussions with regulatory authorities, the further development of the
program, future presentation of additional data from the program and our
future prospects, developments and strategies. The forward-looking statements
are based on current expectations and are subject to known and unknown risks,
uncertainties and other important factors that could cause actual results,
performance and achievements to differ materially from current expectations,
including, but not limited to, those risks, uncertainties and other important
factors described under the caption "Risk Factors" in our Annual Report on
Form 20-F for the year ended December 31, 2024, filed with the SEC and in our
other regulatory filings. These forward-looking statements are based on
assumptions regarding the present and future business strategies of the
Company and the environment in which it will operate in the future. Each
forward-looking statement speaks only as at the date of this press release.
Except as required by law and regulatory requirements, we disclaim any
obligation to update or revise these forward-looking statements, whether as a
result of new information, future events or otherwise.

 

PureTech
Public Relations
publicrelations@puretechhealth.com (mailto:publicrelations@puretechhealth.com)

Investor Relations
IR@puretechhealth.com (mailto:IR@puretechhealth.com)

UK/EU Media
Ben Atwell, Rob Winder

+44 (0) 20 3727 1000
puretech@fticonsulting.com (mailto:puretech@fticonsulting.com)

US Media
Justin Chen
jchen@tenbridgecommunications.com (mailto:jchen@tenbridgecommunications.com)

(( 1 )) Evaluable is defined in the protocol as all patients who received a
minimum one full cycle of LYT-200 (four doses) and had a minimum of one
on-study disease assessment.

 2  Grand View Research, Acute Myeloid Leukemia Treatment Market Size, Share
& Trends Analysis Report By Disease, By Treatment (Chemotherapy, Targeted
Therapy, Immunotherapy), By Route of Administration, By End Use, By Region,
And Segment Forecasts, 2025 Ð 2030

 

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