Cullinan Therapeutics (NASDAQ: CGEM) Surges 17.47% on 31% CRh in Phase 1, FDA Fast Track

Cullinan Therapeutics (NASDAQ: CGEM) surged 17.4693% in pre-market trading on December 9, 2025, following the release of updated Phase 1 data for its investigational FLT3xCD3 bispecific T cell engager, CLN-049. The trial demonstrated a 25% complete response (CR)/complete remission with incomplete recovery (CRh) rate at doses ≥6 µg/kg, with a 31% rate observed at the highest tested dose of 12 µg/kg. The results highlighted durable responses, including measurable residual disease (MRD) negativity in select patients, alongside a manageable safety profile marked by low-grade cytokine release syndrome and febrile neutropenia.

The data, presented at the 67th ASH Annual Meeting, underscore CLN-049’s potential to address unmet needs in relapsed/refractory acute myeloid leukemia (AML), particularly for patients with TP53 mutations. The FDA’s Fast Track designation further accelerates development, with dose escalation and expansion cohorts planned for early 2026. Analysts noted the trial’s alignment with Cullinan’s strategy to advance novel immunotherapies, positioning CLN-049 as a candidate for broad AML patient populations, including those with high-risk genetic profiles.

Clinical trial data for CLN-049 has drawn significant attention from both investors and medical professionals, as the compound's dual targeting of FLT3 and CD3 shows promise in activating T-cells against AML cancer cells. The trial's design emphasizes a careful balance between efficacy and safety, as early-stage bispecific therapies often face challenges with severe cytokine release syndrome. This trial's reported low-grade CRS incidents mark a key differentiator in its safety profile compared to similar therapies in development.

With the recent positive pre-market reaction, CGEM's stock valuation reflects optimism about the drug's potential. However, the long path to commercialization remains, with further trials, regulatory approvals, and manufacturing scalability hurdles ahead. The biotech sector is inherently volatile, and while early data is encouraging, long-term success will depend on robust Phase 2 and Phase 3 results. Investors are advised to remain cautious but attentive to upcoming catalysts in early 2026.

The broader market for AML therapies is expected to grow as personalized and targeted treatments become more mainstream. CLN-049's dual mechanism offers a differentiated approach in a space dominated by conventional chemotherapies and monotherapy immunotherapies. If the drug continues to demonstrate durable responses with manageable side effects, it could carve out a significant niche in the treatment landscape for high-risk AML patients.