Treeline Biosciences

Treeline Biosciences, Inc. is a privately held, clinical-stage biopharmaceutical company founded in 2021 by two medical oncologists, Josh Bilenker (CEO) and Jeff Engelman (CSO). The company pairs selected disease targets with clinically validated drug modalities — small-molecule inhibitors, protein degraders and molecular glues, and targeted-therapy antibody-drug conjugates (TT-ADCs) — and has built capability in all of these modalities in-house rather than relying on outsourced contract research. Its stated therapeutic focus spans oncology, neurological and autoimmune/immunology diseases, with the initial pipeline concentrated in cancer.

As of September 2025, Treeline had three programs entering Phase 1. TLN-121 is a BCL6 protein degrader designed to remove BCL6 from lymphoma cells while limiting off-target toxicity, potentially enabling combination with standard-of-care therapy; its Phase 1 trial (NCT07082803) enrolls patients with B-cell and T-cell lymphomas. TLN-372 is a small-molecule pan-KRAS inhibitor intended for deep, continuous inhibition across KRAS variants beyond G12C, in a Phase 1 study in KRAS-altered solid tumors. TLN-254 is an EZH2 inhibitor in-licensed from Hengrui Pharmaceuticals in 2023 after Phase 2 testing in refractory lymphoma and approved in China for relapsed or refractory peripheral T-cell lymphoma; its Phase 1 trial (NCT06733441) enrolls patients with peripheral and cutaneous T-cell lymphomas. A fourth disclosed program targets BCL-XL and could enter Phase 1 in 2026, with additional undisclosed programs in development.

In June 2026 Treeline announced plans to become publicly traded through a reverse merger with Standard BioTools, with the combined company expected to list on Nasdaq under the ticker "TRLN" and to hold nearly $900 million in cash.

Founding story

Co-founders Josh Bilenker and Jeff Engelman, both medical oncologists with experience leading R&D organizations, joined forces in 2021 to build a company with an in-house discovery team and access to leading-edge technologies, believing that outsourced contract research and a one-and-done pipeline would yield only incremental progress. Bilenker previously founded Loxo Oncology, which developed and commercialized three FDA-approved medicines before being acquired by Eli Lilly (reported at $8 billion in 2019), and previously worked in venture capital and at the FDA; he briefly led Lilly's cancer drug division afterward. Engelman was Global Head of Oncology at the Novartis Institutes for BioMedical Research and earlier led an academic lab and served as Director of Molecular Therapeutics and Director of Thoracic Oncology at Massachusetts General Hospital.

Business model

Treeline discovers and develops proprietary therapeutics in-house and supplements its pipeline with in-licensed clinical assets, funding operations through large private financings rather than commercial revenue. Its model emphasizes an integrated internal discovery organization across biology, chemistry, protein science, computation and clinical development, in contrast with outsourced contract research and single-asset pipelines.

Traction

Three programs entered Phase 1 trials as announced in September 2025 (TLN-121, TLN-372, TLN-254), with a fourth BCL-XL-directed candidate potentially entering Phase 1 in 2026 and further undisclosed programs in development. Cumulative private funding reached approximately $1.1 billion, and the company reported nearly $900 million in cash in connection with its planned public listing.

Latest developments

On 8-9 June 2026, Treeline announced a reverse merger with Standard BioTools that would take it public on Nasdaq under the ticker "TRLN," with Treeline investors holding an estimated 84.5% of the combined company, Standard BioTools shareholders 15.5% plus a contingent value right tied to pre-merger asset sale proceeds, and nearly $900 million in cash at closing, which is estimated for the second half of 2026. Bilenker will lead the combined company with CSO Jeff Engelman and CFO Spencer Smith. A fourth program targeting BCL-XL could begin Phase 1 testing in 2026.