Cessation Therapeutics Announces Oral Presentation of Preliminary Findings from First-in-Human Study of Anti-Fentanyl Monoclonal Antibody, CSX-1004

June 19, 2024 |

4 min read

Cessation Therapeutics, Inc. (“Cessation”), a clinical-stage biotechnology company advancing biologics that target substances of abuse, today announced the presentation of preliminary data from its Phase 1a first-in-human study of CSX-1004, an investigational monoclonal antibody for prophylaxis against fentanyl-related overdose.

Data presented at the annual meeting of the College on Problems of Drug Dependence

CSX-1004 was well-tolerated across the entire dose range, with no dose-limiting toxicities

CSX-1004 is advancing to a Phase 2 Study

CHAPEL HILL, N.C.--(BUSINESS WIRE)-- Cessation Therapeutics, Inc. (“Cessation”), a clinical-stage biotechnology company advancing biologics that target substances of abuse, today announced the presentation of preliminary data from its Phase 1a first-in-human study of CSX-1004, an investigational monoclonal antibody for prophylaxis against fentanyl-related overdose.

The following abstract is being presented as an oral presentation at the annual meeting of the College on Problems of Drug Dependence (CPDD) in Montreal on June 19 at 11:30 am ET. The preliminary data showed that CSX-1004 is safe and well-tolerated under the conditions tested. The exposure data were also predictive of efficacy for blocking fentanyl-induced respiratory depression. CSX-1004 will advance to a Phase 2 proof-of-concept study.

First-in-Human Study of the Safety, Tolerability and Pharmacokinetics of CSX-1004, an Investigational Anti-Fentanyl Monoclonal Antibody

Authors: B. Vince, A. Barrett, N. Jacob, P. Bremer, S. Hull

Date/Time: June 19, 2024 (11:30 am ET)

Preliminary results indicate that CSX-1004 was generally well-tolerated across the dose range tested, with no dose-limiting toxicities. Of the 17 total adverse events (AEs) reported, 16 (94%) were rated as mild in severity. There were no serious AEs. Further, there were no clinically significant laboratory abnormalities, effect on vital signs, or ECG findings. The profile of CSX-1004 exposure in serum was consistent with other IgG monoclonal antibodies, with a fast distribution phase and slower elimination phase yielding a multi-week half-life. For at least one month post-dosing, serum concentrations of CSX-1004 were greater than those demonstrated to block life-threatening fentanyl-induced respiratory depression in nonhuman primates. There was no evidence of immunogenicity (i.e., development of anti-drug antibodies) in blood samples analyzed to date.

“We are encouraged with the safety profile and overall performance of CSX-1004 in this initial Phase 1 study,” said Andy Barrett, PhD, President and Chief Scientific Officer at Cessation Therapeutics. “The finding that serum concentrations of CSX-1004 remained above a minimum threshold for blocking fentanyl-induced respiratory depression for an extended period of time provides added confidence in the capabilities of the molecule. We are advancing this potentially groundbreaking therapy into Phase 2 clinical development.”

“The opioid crisis in America, specifically with illegally manufactured fentanyl and fentanyl analogs, continues to take countless lives and decimate families and loved ones,” stated Dr. Brad Vince, CEO & Chief Medical Officer of Dr. Vince Clinical Research. “CSX-1004, especially secondary to its exceptionally long half-life, has the potential to supply healthcare providers with another treatment and prevention option as they help combat the fentanyl epidemic in this country.”

In this Phase 1a randomized, placebo-controlled, single ascending dose study (NCT06005402), 32 healthy subjects were enrolled. Four doses of CSX-1004 were tested sequentially, beginning with the lowest dose: 1.0, 3.0, 10 and 30 mg/kg. Eight subjects in each cohort were randomized to receive CSX-1004 or placebo in a 3:1 ratio. After each cohort completed dosing, a Safety Monitoring Committee (SMC) reviewed the blinded data to approve escalation to the next higher dose. The trial was conducted at Dr. Vince Clinical Research in Overland Park, KS.

A Phase 2a proof-of-concept study is planned that will evaluate the ability of CSX-1004 to block the respiratory depressant effects of fentanyl in repeated challenges over 28 days in healthy volunteers and patients with Opioid Use Disorder.

About CSX-1004

CSX-1004 is an investigational, recombinant human immunoglobulin G (IgG)1λ monoclonal antibody specific for fentanyl and related synthetic opioids. CSX-1004 sequesters and directly neutralizes fentanyl in the bloodstream, preventing fentanyl from exerting its effects in the brain, including the brain’s respiratory centers. CSX-1004 gained FDA Fast Track designation in October 2023 and is being developed for prophylaxis against fentanyl-related overdose.

About Cessation Therapeutics

Cessation Therapeutics is a clinical-stage pharmaceutical company working to develop novel immunobiologics designed to prevent and protect against overdose. With an initial focus on fentanyl, Cessation’s monoclonal antibodies can be adapted to target future synthetic opioids and other substances. Cessation has the potential to treat a range of substance use disorders and improve the lives of patients and families affected by the addiction crisis. Cessation was founded in 2018 by Mark Pearson and John D. Harkey, Jr., experienced, successful long-term biotech investors. Cessation has been financed through their investment firms Altamont Pharmaceutical Holdings, LLC and JDH Investment Management, LLC, respectively, as well as grant support for the National Institute on Drug Abuse (NIDA). For more information, please visit www.cessationtherapeutics.com.