1 PROJECT SUMMARY 2 There is an urgent need for a rapidly acting antidote for methamphetamine. Methamphetamine 3 (meth) is the fastest growing drug of abuse in the U.S., representing over 798,000 annual emergency department 4 (ED) visits, with deaths increasing 14-fold since 2015 (32,856 deaths in 2021 alone), yet no current therapeutics 5 are available to treat meth intoxication. Our objective is to obtain Federal Drug Administration (FDA) approval 6 for sale and marketing of CS-1103, a small-molecule sequestrant, to treat acute meth intoxication. CS-1103 7 selectively binds meth in blood and dramatically accelerates its removal from the body by clearance into the 8 urine, representing a new approach to the reversal of drug effect: remove the cause and remove the effect. 9 The indication for CS-1103 is to lower the level of methamphetamine in the human body. CS-1103 is 10 well-tolerated in rodent and canine and is highly effective in lowering the level of meth and rapidly reversing 11 its toxic effects in non-human primates. In our current U01 program (5U01DA053054-03), we have achieved 12 key milestones in current Good Manufacturing Practice (cGMP) manufacturing, Good Laboratory Practice (GLP) 13 toxicology and pharmacology studies, and held a pre-Investigational New Drug Application (IND) meeting with 14 the FDA. The current U01 will conclude with completion of the Phase 1a First-in-Human clinical trial. 15 We propose here to further develop CS-1103 by completing Phase 1b and Phase 2a clinical trials. These significant 16 milestones on the path to FDA approval will be achieved via completion of the following Aims: Aim 1 will 17 optimize manufacturing process and produce drug substance and drug product under cGMP. We 18 will produce drug substance and drug product that meet FDA requirements and generate a CMC document. 19 Expected outcome is 100 kg of CS-1103 and 5000 vials of drug product. Aim 2 will demonstrate the safety 20 and tolerability of CS-1103 in the presence of methamphetamine in a Phase 1b clinical trial. The 21 Phase 1b trial is a randomized, double-blinded, placebo-controlled 2-period crossover clinical study to evaluate 22 safety, tolerability, and PK of CS-1103 following a single IV dose after an IV dose of meth in 10 individuals with 23 meth use disorder not seeking treatment. Expected outcome is that CS-1103 is safe, and we can obtain FDA 24 approval to proceed to Phase 2a. Aim 3 will determine dosing requirements for CS-1103 in a Phase 25 2a clinical trial. The Phase 2a trial is an open-label, placebo-controlled, dose range-finding clinical study to 26 evaluate efficacy and dose-response of CS-1103. Single IV dose of CS-1103 will be administered after an IV dose 27 of meth in 64 individuals with meth use disorder not seeking treatment. Objectives are to: 1) establish dose 28 response of CS-1103 to remove meth from the body by quantification of meth in plasma and urine, 2) evaluate 29 efficacy of CS-1103 vs. time after administration of meth, and 3) select CS-1103 dose for Phase 2b/Phase 3 trials. 30 Expected outcome is FDA approval to proceed to the pivotal Phase 2b/Phase 3 trials.

PROJECT NARRATIVE Methamphetamine is the fastest growing drug of abuse in the U.S., representing 800,000 emergency department visits and nearly 35,000 deaths annually. The proposed project addresses the urgent need for a safe, rapidly acting therapeutic to treat methamphetamine overdose. Such an antidote would save lives, improve patient outcomes, and relieve burden on already strained hospital resources.