Authors

Authors: Dan V. Mourich*, Carl E. Ruby, Shay Bracha, Christopher K. Cebra, Laura Crowell Orella, Patrick Iversen

Abstract

Single domain antibodies (SDAb) represent an alternative immunotherapeutic platform for veterinary use. Several SDAb targeting canine PD-1 were previously identified with potential for canine cancer immunotherapy. A lead SDAb, clone STX-1B5, with nanomolar binding to canine PD-1 was selected for evaluation of tolerability in dogs. The anti-PD-1 SDAb was expressed in wild-type Komagataella phaffii (Pichia pastoris) at a 100 mg scale, purified by tangential flow filtration, and quality confirmed controlled for host-cell protein, host-cell DNA, and endotoxin. Single 1.0 mL subcutaneous (SQ) injections of 0.15 to 1.12 mg/kg were administered to three adult Beagle dogs (1 male and 2 female) one per week to allow observations from each dose level prior to dose escalation. The dogs were monitored by a veterinarian on the day of dosing and daily for three days. Administering 1.0 ml of STX-1B5 subcutaneously at 0.146, 0.383 or 1.154 mg/kg in young adult male or female Beagle dogs was well tolerated and did not result in adverse test article-related clinical observations.

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