Could Earlier Treatment and Better Patient Selection Improve Sickle Cell Pain Trials? STArT Investigator Explains

In an interview with Pharmacy Times, Claudia R. Morris, MD, lead investigator and author of the phase 3 Sickle Cell Disease Treatment With Arginine Therapy (STArT) trial and a pediatric emergency medicine physician at Children’s Healthcare of Atlanta, discussed how treatment timing and patient heterogeneity may inform the design of future sickle cell pain trials.

In STArT, participants received the study drug a median of approximately 8 hours after their first intravenous opioid dose. Twenty-three participants had already received their final intravenous opioid before the study drug was administered, making it impossible to determine whether arginine affected their opioid requirements. However, Morris explained that these participants represented only about 10% of the study population and were not the primary reason the trial failed to demonstrate a benefit.

Considering the operational challenges of obtaining informed consent and preparing an investigational therapy in a busy emergency department, Morris characterized the 8-hour interval as relatively efficient. Nevertheless, she said administering treatment earlier—ideally while patients are still in the emergency department—could provide a better opportunity to influence an acute pain episode. Future studies might also evaluate an oral intervention that patients could begin at home. This approach is supported by STArT findings showing that patients who experienced pain for longer than 24 hours before seeking care had longer times to crisis resolution.

Morris also emphasized that severe pain does not represent a single biological condition. Approximately 41% of STArT participants met criteria for chronic sickle cell pain, which may respond differently from acute vaso-occlusive pain. She identified acute chest syndrome as a potential target for future arginine research because affected participants remained hospitalized longer and had clearer evidence of vaso-occlusion.

Future trials could also select patients with documented arginine deficiency or use biomarkers associated with hemolysis, nitric oxide depletion, inflammation, and organ injury. According to Morris, narrowing enrollment to biologically defined patient groups may allow researchers to evaluate whether arginine benefits specific sickle cell phenotypes that broad, pain-based eligibility criteria cannot adequately distinguish.