Treatment discontinuation in desmoid tumors: Factors associated with better outcomes after sorafenib discontinuation.

Abstract

11562 Background: Sorafenib has shown effectiveness in managing desmoid tumors. However, the optimal duration of systemic therapy and the outcomes following its discontinuation remain unknown. This study investigates the outcomes of patients who discontinued sorafenib, aiming to provide guidance for clinicians on treatment cessation. Methods: We conducted an international, multi-institutional retrospective analysis of patients treated with sorafenib who discontinued therapy with no immediate plans to initiate a new treatment. We assessed whether the duration of sorafenib use (6 months, 1 year, or 2 years), the reason for discontinuation (side effects or shared decision-making), and the treatment response at the time of discontinuation influenced the likelihood of requiring subsequent treatment (treatment free survival, TFS) or experiencing disease progression (progression free survival, PFS). Kaplan-Meier curves were used for survival analysis, and group comparisons were performed using the log-rank test. Results: Between 2005 to 2022, a total of 48 patients were identified meeting the eligibility criteria. Three (6%) patients received therapy for less than 6 months, thirteen (27%) received less than 12 months, and thirty (63%) received less than 24 months. Seventeen (35%) patients stopped therapy due to side effects with the remaining thirty-one (65%) patients discontinuing due to other reasons, such as patient preference, provider decision, or payment coverage. Four (8%) patients experienced progression of disease while 38 (79%) had stable disease or partial response. The most common side effects were diarrhea (52%), palmar-plantar erythrodysesthesia syndrome (46%), and fatigue (23%). Patients who received less than 6 months of sorafenib treatment prior to discontinuation had a TFS of 10.1 months, compared to 54.5 months for over 6 months of duration (p < 0.001). At the 12-month mark, less than 12 months had median TFS of 49.1, compared to 54.5 for longer (p = 0.2). At the 24-month mark, less than had a median TFS of 49.1, compared to 54.5 for longer (p = 0.1). Other factors did not emerge as statistically significant (p > 0.05). Conclusions: Our data demonstrates the duration of sorafenib treatment is a significant indicator for future treatment need. Reaching the 6-month mark could be indicative of an important checkpoint, although the 1- and 2-year marks are also associated with a clinically, but not statistically, significant reduction in likelihood for future treatment. Clinicians and patients should be aware that duration is an important consideration for future outcomes in desmoid tumor treatment, and to factor it into shared decision-making.