Tecovirimat Use under Expanded Access to Treat Mpox in the United States, 2022-2023

Abstract

Background: During the ongoing outbreak of clade II monkeypox virus (MPXV), many U.S. patients were prescribed tecovirimat, an antiviral drug that was made available under an expanded access Investigational New Drug (EA-IND) program. We evaluated EA-IND data to summarize characteristics of treated patients, outcomes, and serious adverse events (SAEs).

Methods: We evaluated data from patients prescribed tecovirimat from May 29, 2022, through July 10, 2023. Baseline patient characteristics, clinical courses, and outcomes were evaluated via intake forms, outcome forms, and patient diaries. Data were summarized in aggregate by human immunodeficiency virus (HIV) status and by comorbidities of special interest. Reported SAEs were also compiled.

Results: Tecovirimat was prescribed for over 7100 patients in the United States, most often for lesions in sensitive anatomical areas, such as certain anogenital lesions (83.5%; 5135 out of 6148 patients), and pain (52.5%; 3227 out of 6148 patients). The demographic and clinical characteristics mirrored those of patients worldwide. Among the 7181 patients with returned intake forms, 1626 also had returned outcome forms (22.6%). Many patients with severe immunocompromise (e.g., HIV with CD4 counts <200 cells/μl) received multiple courses of tecovirimat (43.1%; 22 out of 51 patients), including intravenously, and often experienced poor outcomes (35.3%; 18 out of 51 patients). Overall, 223 SAEs and 40 deaths were reported. Most SAEs were among patients who were severely immunocompromised, one of whom experienced hallucinations after tecovirimat was administered at twice the standard dose.

Conclusions: Tecovirimat was used extensively. The returned EA-IND data suggest that life-threatening or protracted infections occurred in persons who were severely immunocompromised. SAEs were not commonly reported. The EA-IND data are not definitive; controlled clinical trial data are essential to elucidating if and how tecovirimat should be used.

Figure 1.

Assessment of Returned EA-IND Report Forms for Patients Prescribed Tecovirimat for Treatment of Mpox from May 29, 2022, through July 10, 2023. PCR denotes polymerase chain reaction; and, EA-IND, expanded access Investigational New Drug.

Figure 2.

Summary of Returned EA-IND Data Elements Matched and Analyzed for Patients Prescribed Tecovirimat for Treatment of Mpox from May 29, 2022, through July 10, 2023. The figure shows the assessment time points that correspond to each expanded access Investigational New Drug form: assessment with the intake form at baseline, when tecovirimat was prescribed; an outcome form for days 1 to 7 of tecovirimat treatment; an outcome form with data for days 8 to 14 of tecovirimat treatment; the outcome form with data after the completion of tecovirimat treatment (posttreatment); and/or a patient diary, filled in daily from the start to the completion of tecovirimat treatment. A single outcome form may have included one or more assessments during treatment and/or posttreatment. The figure was created using the UpSetR software package.^, EA-IND denotes expanded access Investigational New Drug.

Figure 3.

The Number of Patients Deemed to Have Probable or Confirmed Mpox in the United States versus the Number of Patients Prescribed Tecovirimat for Whom Intake Form Was Returned and Included in Analysis from May 29, 2022, through July 10, 2023. Mpox outbreak case surveillance data are available at https://www.cdc.gov/poxvirus/mpox/response/2022 (accessed February 1, 2024). It is not known how many of the patients prescribed tecovirimat would also have been deemed to have a probable or confirmed mpox infection.