Real-world data on the effectiveness and safety of interferon-alpha-2a intralesional injection for the treatment of focally recalcitrant mycosis fungoides

Background: Focally recalcitrant mycosis fungoides (MF) is challenging to treat. Despite interferon (IFN)-α intralesional injection having been tested in randomized controlled trials for the treatment of patch or early plaque lesions of MF, no real-world data regarding this therapy for focally recalcitrant MF has been reported. This study aimed to evaluate the effectiveness and safety of IFN-α-2a intralesional injection in focally recalcitrant MF.

Methods: Data on all cases of focally recalcitrant MF treated by IFN-α-2a intralesional injection in Peking Union Medical College Hospital from January 1, 2015 to December 31, 2019 were retrospectively retrieved. Based on clearance of injected lesions and the proportion of adverse events (AEs), the effectiveness and safety of the treatment were analyzed, respectively.

Results: Of the 15 patients included, 10 (66.7%) achieved complete response (CR), and 1 (6.7%) patient had partial response. The overall response rate was 73.3%. The clearance rate of lesions in the sun-exposed areas was significantly higher than that in the non-sun-exposed areas (P<0.01). The CR rate in patients with disease duration of less than 20 years was significantly higher than that in the patients with disease duration of at least 20 years (P<0.05). Four (26.7%) patients had stable disease (SD). The median event-free survival (EFS) was 4.0 months (95% CI, 1.8-6.1 months; range, 1-28+ months). There were no severe acute or chronic side effects.

Conclusions: IFN-α-2a intralesional injection is an effective and safe treatment modality for the treatment of focally recalcitrant MF.