Cullinan Therapeutics, Inc. filed a Current Report on Form 8-K on November 4, 2026, disclosing updated clinical data from its CLN-049 Phase 1 dose escalation trial in patients with relapsed or refractory acute myeloid leukemia or myelodysplastic syndrome, ahead of a December presentation at the 68th American Society of Hematology Annual Meeting and Exposition.

Key Highlights

  • Enrollment: As of the data cutoff, 87 patients (76 AML, 11 MDS) were enrolled across 13 cohorts with a target dose range of 1.5 to 24 µg/kg, according to the filing.
  • CRS reduction: A two step-up dosing regimen reduced cytokine release syndrome incidence from 36% (13/36 patients) to 26% (7/27 patients), with no Grade 3 or higher events in the two step-up group.
  • Efficacy at 12 µg/kg: At the 12 µg/kg target dose level, the company reported a CRc rate of 21% (6/29 patients) and an overall response rate of 45%.
  • Higher ORR in lower step-up subset: Among patients at 12 µg/kg who received a starting step-up dose of 1.5 µg/kg or lower, the CRc rate was 26% (5/19 patients) and the ORR was 53%, the filing stated.
  • Transaminase elevation mitigation: The two step-up dosing regimen reduced transaminase elevations to 4% (1/27 patients); the filing noted these elevations were "asymptomatic, reversible, and not associated with other liver lab abnormalities."
  • Durable responses: Two responding patients remained on CLN-049 treatment for longer than 12 months without further consolidation, and four additional responding patients received CLN-049 as a bridge to allogeneic hematopoietic stem cell transplantation.

CLN-049 Phase 1 Findings in AML and MDS: Dose Regimen and Response Data

According to the filing, Cullinan Therapeutics (NASDAQ:CGEM) shared updated data from its Phase 1 dose escalation trial of CLN-049 on November 4, 2026. The trial enrolled 87 patients across 13 cohorts. The company reported that immune effector cell-associated neurotoxicity syndrome (ICANS) was uncommon, occurring in 6% of patients (5/87), with one Grade 3 event, and all events were described as self-limiting. Grade 3 or greater treatment-emergent adverse events occurring in more than 10% of patients included febrile neutropenia (18%), transaminase elevations (14%), and pneumonia (12%).

The filing described how implementation of a two step-up dosing regimen (1 or 1.5 µg/kg to 6 µg/kg) reduced both the incidence and severity of cytokine release syndrome relative to a one step-up regimen. At the 6 µg/kg target dose level, 80 efficacy-evaluable patients contributed data showing a CRc rate of 19% (3/16 patients, all complete responses) and an ORR of 25%. Measurable residual disease-negative responses by multiparameter flow cytometry were observed in five patients across the study.

The company disclosed that these results indicated "a two step-up dosing regimen on day one (1.5 µg/kg) and day four (6 µg/kg) provided optimal immune priming and favorable clinical safety," and that the highest CRc rates were observed at target dose levels of 6 or 12 µg/kg. The filing noted that CLN-049 is being further explored in an ongoing Phase 2 clinical trial. The updated data are scheduled for presentation at the 68th American Society of Hematology Annual Meeting and Exposition in December, as stated in the filing.

What Was Disclosed

Cullinan Therapeutics filed an 8-K on November 4, 2026, releasing updated Phase 1 clinical trial data for CLN-049 in relapsed or refractory AML and MDS patients, covering safety, dosing regimen effects, and efficacy response rates across multiple dose levels.