The HEAL (Helping to End Addiction Long-term) Initiative and BPN programs have launched a series of collaborative drug discovery and development projects focused on supporting preclinical optimization and development of safe, effective, and non-addictive small molecule and biologic therapeutics to treat pain and other neurological disorders. These projects will be developing therapeutic candidates through an iterative process of lead optimization, in vitro and in vivo testing. A component of this process will be the conduct of in vivo maximum tolerated dose (MTD) and doserange finding (DRF) toxicity assessment of compounds. This task order will cover rodent and nonrodent (MTD) and DRF studies of compounds generated by the HEAL or BPN Program.