Jubilant Therapeutics Announces First Preliminary Clinical Data from Ongoing Phase 1/2 Study of JBI-802 in Patients with Myeloproliferative Neoplasms at SOHO 2026

Presentation highlights data demonstrating that the dual LSD1/HDAC6 inhibitor achieves rapid and sustained dose-responsive reductions in platelet counts in patients with essential thrombocythemia (ET), with consistent activity also observed in polycythemia vera (PV) and other myeloproliferative neoplasms (MPNs)

YARDLEY, Pa., Sept. 15, 2026 /PRNewswire/ -- Jubilant Therapeutics Inc., a clinical-stage biopharmaceutical company advancing precision therapies for hematological malignancies, today announced the presentation of the first clinical data from its ongoing Phase 1/2 study of JBI-802, the company's first-in-class oral dual LSD1/HDAC6 inhibitor, at the Society of Hematologic Oncology (SOHO) 2026 Annual Meeting, which took place during September 9-12, 2026, in Houston, Texas. The data demonstrated the first clinical evidence supporting dual inhibition of LSD1 and HDAC6 as a differentiated therapeutic approach for patients with myeloproliferative neoplasms (MPNs), a group of blood cancers, including essential thrombocythemia (ET) and polycythemia vera (PV).

The presentation titled, 'Breaking the Limits of LSD1 Inhibition: Dual LSD1/HDAC6 Epigenetic Targeting with JBI-802 in MPNs,' was given by Dr. Sandra Aung, Chief Development Officer, and reported clinical activity across patients (n = 12) with ET, PV, myelofibrosis (MF) and myelodysplastic syndrome/ myeloproliferative neoplasm (MDS/MPN), with rapid, sustained and durable, dose-dependent reductions in platelet counts with a manageable safety profile.

Clinical Highlights

Rapid and Meaningful Platelet Reductions Across MPN Subtypes

As of June 30, 2026, twelve patients across four dose cohorts (5 mg, 7 mg, 15 mg, and 20 mg) were evaluated in the dose-escalation portion of the study.

Key findings included:

• Platelet reductions were observed across ET, PV, MF and MDS/MPN patients, with clinical activity seen across JAK2, CALR, and MPL-mutated disease.
• At the 15 mg dose level, all three patients achieved rapid and substantial platelet reductions of 75%, 72%, and 81%, respectively within the first 30 days of treatment.
• 9 of 9 ET/PV patients, evaluable for platelet reduction, achieved reductions ranging from 36-91%. Four ET/PV patients with extreme thrombocytosis (baseline platelet counts >1,000 × 10⁹/L) achieved rapid platelet reductions of 30% to 75% within the first 30 days of treatment and subsequently achieved maximum platelet reductions ranging from 72% to 91% during treatment.
• Platelet responses were durable and maintained through dose modification, supporting a controllable pharmacokinetic-pharmacodynamic relationship.

Manageable Safety Profile

As of June 30, 2026, data cutoff:

• No investigator assessed dose-limiting toxicities were observed at the 5 mg, 7 mg, or 15 mg dose levels.
• One dose-limiting thrombocytopenia event was observed at the 20 mg dose level and was successfully managed through protocol-defined dose modification. Following dose reduction to 10 mg, the patient remains on treatment with platelet counts maintained within the normal range.
• Of the 12 treatment-emergent adverse events (TEAEs) reported, 10 were Grade 1 or 2 in severity and two were Grade 3 or higher. No patients discontinued treatment due to thrombocytopenia or treatment-related adverse events.

"These preliminary findings highlight several characteristics that we believe are important for the long-term management of myeloproliferative neoplasms," said Daniel O'Connor, President and Chief Executive Officer of Jubilant Therapeutics. "In addition to rapid and sustained reductions in platelet counts across multiple MPN subtypes, JBI-802 has demonstrated a favorable tolerability profile, with patients remaining on treatment for more than six months and continuing to derive clinical benefit. We are particularly encouraged by the combination of meaningful clinical activity, prolonged treatment exposure, and a pharmacokinetic profile that supports flexible dose adjustment. Together, these data suggest JBI-802 has the potential to offer a differentiated therapeutic option for patients living with these chronic hematologic malignancies."

A Novel Approach to Epigenetic Targeting in MPNs

JBI-802 is the only oral dual LSD1/HDAC6 inhibitor currently in clinical development and is administered once daily. JBI-802 was designed to simultaneously inhibit LSD1 and HDAC6, two complementary epigenetic regulators involved in the abnormal blood cell proliferation and production characteristic of MPNs. Preclinical studies have suggested that dual inhibition may provide broader biological activity than selective inhibition of either pathway alone.

The molecule has a short half-life of approximately 1.5 to 2 hours and is rapidly cleared from circulation, a profile that may offer several advantages for chronic treatment including predictable systemic exposure, rapid reversibility of pharmacologic effects, flexible dose titration and the ability to promptly manage on-target hematologic effects through dose titration.

The ongoing Phase 1/2 study (NCT07612280) is evaluating JBI-802 in patients with relapsed, refractory, or treatment-intolerant MPNs. Study objectives include evaluation of safety and tolerability, identification of the recommended Phase 2 dose, and assessment of preliminary efficacy through platelet reduction, durability of hematologic response, and molecular outcomes.

Enrollment is ongoing and Jubilant Therapeutics expects to present additional efficacy, safety, and molecular response data as the program advances.

The poster is available on the Jubilant website at SOHO 2026 – JBI-802 Poster

About Myeloproliferative Neoplasms (MPNs)

Myeloproliferative neoplasms (MPNs) are a group of chronic blood cancers driven by mutations in genes such as JAK2, CALR, and MPL, causing the bone marrow to overproduce blood cells. Essential thrombocythemia (ET) is characterized by excess platelet production, while polycythemia vera (PV) is characterized by excess red blood cell production; both are associated with an increased risk of blood clots and can progress to more advanced disease over time. Despite available treatments, many patients with ET and PV continue to experience inadequate disease control, underscoring the need for new therapeutic approaches.

About JBI-802

JBI-802 is an orally administered dual inhibitor of lysine-specific demethylase 1, or LSD1, and histone deacetylase 6, or HDAC6. JBI-802 is the only dual LSD1/HDAC6 inhibitor currently in clinical development. JBI-802 simultaneously targets multiple disease-relevant processes, including abnormal megakaryocyte differentiation, platelet production, leukocyte proliferation and inflammatory signaling. JBI-802 is being evaluated in an ongoing Phase 1/2 clinical study in patients with essential thrombocythemia, or ET, and other thrombocytosis-predominant myeloid malignancies. Emerging clinical data has demonstrated rapid reductions in platelet counts and activity across multiple molecular subtypes of disease. 

About Jubilant Therapeutics, Inc.

Jubilant Therapeutics is a clinical-stage biopharmaceutical company advancing precision therapeutics for oncology and autoimmune diseases. Jubilant Therapeutics leverages deep expertise in medicinal chemistry, structure-based drug design, translational science, and clinical development to discover and develop differentiated small-molecule medicines that address significant unmet medical needs. The company's lead clinical asset, JBI-802, is a first-in-class dual LSD1/HDAC6 (CoREST) inhibitor currently being evaluated in Essential Thrombocythemia (ET)/ Myeloproliferative Neoplasms (MPN) and other oncology indications. Jubilant's pipeline also includes JBI-3041, a selective first-in-class PAD4 inhibitor with potential applications across cancer and autoimmune diseases. Headquartered in Yardley, Pennsylvania, Jubilant Therapeutics is committed to delivering innovative therapies that improve outcomes for patients worldwide.  For more information, please visit www.jubilanttx.com or follow us on Twitter @JubilantTx and LinkedIn.

SOURCE Jubilant Therapeutics