Feasibility of a digital therapeutic for experiential negative symptoms of schizophrenia: results from an exploratory study

Experiential negative symptoms (ENS) of schizophrenia, such as asociality, anhedonia, and avolition, are associated with poor outcomes, yet no FDA-approved pharmacotherapies currently exist specifically to target these symptoms. With the increasing use of smartphones, evidence-based digital interventions delivered by prescription digital therapeutics (DTx) may present an opportunity to address the unmet therapeutic need for ENS of schizophrenia. CT‑155/BI 3972080 (CT-155) is being developed as a smartphone-based prescription DTx for the treatment of ENS. A multicenter, 7-week, single-arm, open-label, exploratory study (NCT05486312) evaluated the engagement, adherence, potential effectiveness, acceptability, user experience, and safety of an abbreviated version of CT-155 (CT‑155 beta). Engagement and adherence with CT-155 beta were measured passively throughout the study using the study app. Change in ENS severity was assessed using the clinically administered clinical assessment interview for negative symptoms, motivation, and pleasure subscale (CAINS-MAP). Acceptability and user experience were assessed using the validated Mobile App Rating Scale (MARS) along with an episodic user experience survey, respectively. Fifty participants with a clinically confirmed schizophrenia diagnosis were enrolled; 80% were male, 58% were Black or African American, and the median (range) age was 53.5 (23-64) years. At baseline, participants' mean (SD) CAINS-MAP total score was 20.5 (8.3). Most participants (n = 43; 86%) completed the 7-week study. Participants readily engaged with CT-155 beta. Kaplan-Meier retention analysis showed that 84% of participants (N = 42/50) engaged with CT-155 beta (i.e., last app open) until the end of the study period. Daily app check-ins were completed on a median (IQR) of 43.0 (19-47) days of the 49 possible days (88%). The median (IQR) duration of engagement was 11.6 (8.1-16.1) min per session. Additionally, adherence with CT-155 was high, with participants completing a median of 18 (IQR 13-20) of the 21 therapeutic lessons available. After 7 weeks of CT-155 beta usage, the mean change in within-subject CAINS-MAP score was 3.6 points from baseline (95% CI 1.3, 5.8; p = 0.0026; baseline: 20.4 (8.6) Week 7: 16.8 (7.7)). Most participants (91%; n = 39/43) rated CT-155 beta functionality using MARS assessment as acceptable or higher, with an overall mean MARS functionality subscale score of 4.2 points out of 5 points, with 5 corresponding to "excellent" at Week 7. The end of study participant feedback survey showed that 95% (n = 42/44) of participants would recommend using CT-155 beta. No app-related adverse events nor severe adverse events leading to discontinuation of the study were reported. Overall, the study demonstrated the feasibility of CT-155 beta in participants with ENS of schizophrenia. Results from this feasibility study show the potential of evidence-based DTx approaches to address ENS of schizophrenia.