Predictors of anamorelin discontinuation in patients with cancer-associated cachexia undergoing chemotherapy: A retrospective observational study.

BACKGROUND: Anamorelin is the first drug approved for treating cancer-associated cachexia in Japan. However, factors influencing its discontinuation beyond a 12-week period have not been well studied. Moreover, death occurs in patients with cancer-associated cachexia and may compete with treatment discontinuation. OBJECTIVE: To investigate predictors of anamorelin discontinuation during a 48-week observation period, accounting for competing mortality risk. MATERIALS AND METHODS: This retrospective observational study investigated patients who commenced anamorelin administration for cancer-associated cachexia between October 1, 2021, and December 31, 2023, at Kindai University Nara Hospital. Predictors of discontinuation were evaluated using a multivariate Cox proportional hazards model to estimate HRs and 95% CIs. The Fine-Gray subdistribution hazards model was additionally applied, treating death as a competing event. A total of 93 patients were evaluated. RESULTS: An Eastern Cooperative Oncology Group performance status (PS) of ≥ 2 (adjusted HR 2.25, 95% CI 1.33 - 3.80, p = 0.003) and a prognostic nutritional index (PNI) of ≤ 39.6 (adjusted HR 1.79, 95% CI 1.10 - 2.90, p = 0.019) were predictors of discontinuation. Conversely, the Fine-Gray subdistribution hazards model identified PS ≥ 2 as significant (adjusted SHR 1.95, 95% CI 1.17 - 3.24, p = 0.010). CONCLUSION: In patients with cancer-associated cachexia, baseline PS and PNI were associated with anamorelin discontinuation. Furthermore, competing risk analysis demonstrated PS was the primary determinant of anamorelin discontinuation, whereas PNI may be more closely associated with mortality risk. Therefore, early diagnosis of cancer-associated cachexia and timely initiation of anamorelin before declines in PS and PNI may enable long-term administration.