Phanes Therapeutics' PT217 has received Fast Track designation from the U.S. Food and Drug Administration (FDA) for the treatment of patients with metastatic de novo or treatment-emergent neuroendocrine prostate cancer (NEPC). This marks the second Fast Track designation for PT217, highlighting its potential to address unmet needs in aggressive cancers. The FDA's decision underscores the urgent need for new therapies for NEPC, a particularly challenging form of prostate cancer with limited treatment options.
PT217 is a first-in-class native IgG-like bispecific antibody (bsAb) that targets DLL3 and CD47. It is being developed for the treatment of patients with small cell lung cancer (SCLC) and neuroendocrine carcinoma, including NEPC. The bispecific antibody is designed to simultaneously engage DLL3, a protein highly expressed in neuroendocrine tumors, and CD47, a protein that inhibits macrophage-mediated killing of cancer cells. By targeting both DLL3 and CD47, PT217 aims to directly kill tumor cells and enhance the anti-tumor immune response.
Clinical Development and Ongoing Trials
The multi-center Phase I/II clinical trial of PT217 (NCT05652686), known as the SKYBRIDGE study, is currently evaluating the safety, tolerability, pharmacokinetics, and preliminary efficacy of PT217 in patients with advanced or refractory cancers expressing DLL3. The SKYBRIDGE study is enrolling patients across multiple sites in the United States. A Phase I clinical trial of PT217 is also ongoing in China (CTR20242720).
The SKYBRIDGE trial includes a dose escalation phase (Part A), a dose expansion phase (Part B), a chemotherapy combination phase (Part C) and an ICI combination therapy phase (Part D). In Part D, PT217 will be administered in combination with atezolizumab (Tecentriq) with or without chemotherapy (carboplatin plus etoposide).
Collaboration with Roche
Phanes Therapeutics has entered into a clinical supply agreement with Roche to study PT217 in combination with Roche's anti-PD-L1 therapy, atezolizumab. This collaboration aims to explore the potential synergistic effects of combining PT217 with immune checkpoint inhibition in DLL3-expressing cancers.
Prior Designations
In addition to the Fast Track designation for NEPC, PT217 was previously granted Fast Track designation for extensive-stage small cell lung cancer (ES-SCLC) with disease progression following platinum chemotherapy with or without a checkpoint inhibitor. PT217 has also received orphan drug designations for the treatment of small cell lung cancer and neuroendocrine carcinoma (NEC).
