Cullinan Therapeutics, Inc. (CGEM) · Nov 4, 2026 · Other events

Cullinan CLN-049 data show safer dosing but mixed AML efficacy

Phase 2 dose selected — 12 µg/kg: 26% CRc and 53% ORR with low-step-up dosing

Cullinan’s CLN-049 clinical update supports a safer Phase 2 regimen in AML, though efficacy at the selected doses is mixed.

Cullinan is moving CLN-049, its FLT3xCD3 T-cell engager, from dose escalation into a potentially registrational Phase 2 program for relapsed/refractory AML; the first Phase 2 patient was dosed in October 2026, and the company had already flagged longer-follow-up data for December. This filing therefore confirms an expected milestone, but adds the regimen-specific safety and efficacy detail that matters for whether the program is genuinely improving.

The clearest advance is dosing optimization. Moving to two step-up doses reduced CRS from 36% with one step-up to 26%, and removed Grade 3 CRS in the 27-patient two-step group; transaminase elevations also fell to 4% in that group. The safety improvement is meaningful because it makes the selected regimen more workable for Phase 2, although febrile neutropenia remained the most common serious adverse event at 18%. 〔0〕

Efficacy is encouraging but not a clean step-up from the prior readout. In December 2025, the 12 µg/kg group had shown a 31% CRc rate in 16 patients; this update reports 21% CRc across 29 patients at 12 µg/kg, improving to 26% among patients who received the low starting step-up dose, with a 53% ORR. That suggests the dosing fix may preserve activity, but the small, non-randomized Phase 1 dataset does not yet establish a stronger response signal than the earlier snapshot.

MeasureCurrent dataPrior readout
Enrolled patients (Other Events)8745
CRS rate (Other Events)26% two-step36% one-step
CRc at 12 µg/kg (Other Events)26% selected regimen31%
ORR at 12 µg/kg, low step-up (Other Events)53%—
Grade ≥3 febrile neutropenia (Other Events)18%20%

The business story advances operationally more than clinically. The filing supports the company’s decision to take 6 and 12 µg/kg forward and adds signs of durable activity, including five MRD-negative responses, two patients treated beyond 12 months, and four patients bridged to transplant. But those observations remain too small and selected to rewrite the program’s efficacy case before Phase 2 data mature. 〔1〕 〔2〕

Bottom line: This is a modestly positive development because Cullinan appears to have solved an important tolerability problem and kept meaningful activity at the intended Phase 2 doses. It strengthens the path into Phase 2, but the efficacy data are not yet a decisive upgrade from the earlier clinical signal.

What to watch next

ASH poster presentation, December 13, 2026

Original filing on SEC EDGAR

More Cullinan Therapeutics, Inc. news

Cullinan CLN-049 data show safer dosing but mixed AML efficacy | CGEM Stock News
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