Celldex Pharmaceuticals has agreed to acquire Kolltan Pharmaceuticals for up to $235 million in a deal designed to expand the buyer’s antibody and immuno-oncology portfolio.

The acquisition would expand Celldex’s pipeline to seven drug candidates under study in a range of difficult-to-treat oncology indications, including therapeutic antibodies, antibody–drug conjugates (ADCs), and immune system modulators, as well as two active preclinical programs. The buyer said the expanded pipeline will allow for novel combination treatments, several of which are already under study.

Privately held Kolltan focuses on discovering and developing novel antibody-based drugs targeting receptor tyrosine kinases (RTKs). Kolltan has generated clinical and preclinical data showing that its candidates can help overcome tumor resistance mechanisms in patients who have failed other cancer therapies—mechanisms associated with current tyrosine kinase inhibitors. Kolltan’s candidates include:

  • KTN0158, intended to prevent KIT activation in tumor cells and mast cells by blocking receptor dimerization. The humanized monoclonal antibody has shown promising preclinical data and is in a Phase I dose escalation study in refractory gastrointestinal stromal tumors (GIST).
  • KTN3379, a humanized monoclonal antibody designed to block both ligand-independent and ligand-dependent ErbB3 (HER3) signaling by binding to a unique epitope. According to Kolltan, “meaningful” responses and stable disease has been seen in a Phase Ib study in cetuximab (Erbitux®)-refractory patients in head and neck squamous cell carcinoma and in BRAF-mutant non-small-cell lung cancer (NSCLC).
  • A program to generate antibodies that modulate the TAM family of RTKs, consisting of Tyro3, AXL, and MerTK, that are expressed on tumor-infiltrating macrophages, dendritic cells, and some tumors. The companies reason that modulating TAM pathways may enable development of additional drugs designed to overcome resistance mechanisms, especially in combination with Celldex or external product candidates, or with existing approved therapies.

“We firmly believe Celldex is uniquely positioned to advance our antibody portfolio targeting RTKs to improve outcomes for patients and create optimal value for our shareholders,” Kolltan President and CEO Gerald McMahon, Ph.D., said in a statement.

Celldex has agreed to acquire Kolltan in a stock-for-stock transaction, beginning with an upfront payment of approximately $62.5 million in equity. Celldex also agreed to pay Kolltan shareholders up to $172.5 million in additional payments tied to achieving development, regulatory, and commercial milestones.

The boards of Celldex and Kolltan have unanimously approved the transaction, which is expected to be completed by year’s end, subject to Kolltan stockholder approval and other customary closing conditions.

The deal comes 8 months after Celldex terminated a Phase III ACT IV  trial for its glioblastoma candidate Rintega® (rindopepimut) after the study’s independent data monitoring committee concluded the candidate would not achieve statistical significance for its primary endpoint of overall survival in patients with newly diagnosed epidermal growth factor receptor variant III (EGFRvIII)-positive glioblastoma.

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