Solid Tumors


Clinical Candidate: PNT6555


PNT6555 is an early-stage radioligand that targets Fibroblast Activation Protein-α (FAP-α), which is highly expressed on a wide range of solid tumors. PNT6555 was developed in collaboration with Dr. William Bachovchin at Tufts, a leader in designing inhibitors of DASH family proteases, including FAP.

FAP-α is a compelling pan-cancer target for imaging and therapy because it is found in greater than 90% of epithelial tumors.

PNT6555 targets FAP-α with best-in-class tumor retention and normal tissue clearance, exhibiting ideal radiopharmaceutical characteristics: delivery of large doses of radiation directly to a wide variety of tumors while being flushed from healthy tissues.

The Phase 1 clinical trial is expected to commence in summer 2022 in Canada and will use a gallium-68 (68Ga)-based PNT6555 molecular imaging agent to select patients to receive a no-carrier-added (n.c.a.) lutetium-177 (177Lu)-based PNT6555 therapeutic agent. The Phase 1 clinical protocol will evaluate PNT6555 in ~30 patients in five FAP-avid cancer indications: colorectal, pancreatic, esophageal, melanoma, and soft tissue sarcoma.

Dosing will start at 4 GBq with each subsequent dose level increasing by 4 GBq and 2 GBq dose de-escalations. Each 177Lu PNT6555 dose will be followed by a 6-week interval. 68Ga-PNT6555 PET/CT imaging will be conducted approximately 90 minutes post injection, and dosimetry will be completed at the time of first 177Lu-PNT6555 dose and each subsequent cycle. The primary objective of the study is to determine the maximum tolerated dose (MTD), and the Recommended Phase II Dose (RP2D). The company expects to present initial imaging and dosimetry data in early 2023.