WATERTOWN, Mass., September 2, 2026

Treeline Biosciences, Inc. announced a clinical trial collaboration and supply agreement with Roche to evaluate its investigational BCL6 degrader TLN-121 in combination with Roche’s CD20xCD3 T-cell-engaging bispecific antibodies, glofitamab-gxbm (COLUMVI®) and mosunetuzumab-axgb (LUNSUMIO®), in patients with B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). Under the agreement, Treeline will sponsor and conduct the Phase 1 dose-escalation and expansion study, while Roche will provide glofitamab and mosunetuzumab for specific expansion cohorts. Treeline expects combination dosing in the expansion cohorts to begin in the fourth quarter of 2026, expanding the clinical evaluation of TLN-121 beyond its ongoing single-agent development.

TLN-121 Advances Into Combination Development

The collaboration is based on preclinical evidence suggesting that TLN-121 may enhance the activity of T-cell-directed cancer immunotherapies. TLN-121 has already demonstrated single-agent activity in an ongoing Phase 1 study, including complete responses in patients with late-line DLBCL, follicular lymphoma (FL), and T follicular helper peripheral T-cell lymphoma (TFH PTCL). Treeline is now evaluating whether degrading BCL6 can improve the effectiveness of therapies that recruit T cells to attack malignant B cells. Roche’s glofitamab and mosunetuzumab are designed to engage CD20 on B cells and CD3 on T cells, creating an immune-mediated mechanism for eliminating lymphoma cells.

Preclinical Data Support Immune Combination

BCL6 is a transcriptional repressor that can contribute to immune evasion in B-cell lymphomas by suppressing genes involved in effective interactions between tumor cells and T cells. In DLBCL cell-line studies, TLN-121 restored expression of T-cell-recruiting cytokines and immune synapse genes, providing a biological rationale for combining the degrader with T-cell-engaging therapies. In an aggressive DLBCL mouse xenograft model containing human T cells, the combination of TLN-121 with a CD20xCD3 bispecific antibody produced complete tumor regressions in four of six mice, compared with zero of six animals treated with TLN-121 alone and one of five receiving the antibody alone. These findings suggest that BCL6 degradation could potentially make lymphoma cells more susceptible to immune-mediated attack..

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Expanding TLN-121 Across Immunotherapies

Treeline also reported activity when TLN-121 was combined with CD19-directed CAR-T cell therapy in an aggressive DLBCL xenograft model. The combination reduced tumor size in four of six mice and produced complete tumor regression in two of six, while neither monotherapy produced tumor shrinkage or regression in the model. The company plans to investigate these findings clinically through the Roche collaboration, while continuing development of TLN-121 as a potential treatment for B-cell malignancies. The planned Phase 1 combination cohorts will provide an opportunity to assess safety, tolerability, dosing and preliminary antitumor activity when TLN-121 is paired with established T-cell-engaging approaches.

Source:Treeline Biosciences,, press relese