Real-world experience with trastuzumab deruxtecan in patients with metastatic HER2-positive breast cancer and HER2-positive gastric cancer: A retrospective study

Aim. To evaluate the effectiveness of trastuzumab deruxtecan in real-world practice in the Russian Federation. Materials and methods. We performed a retrospective analysis of clinical case series related to the use of trastuzumab deruxtecan (N=15) in the setting of a single clinical center, University Headache Clinic (Dr. Laskov's Clinic), as part of the program for the import of an unapproved drug as a life-saving measure. The overall survival, progression-free survival, and objective response rate were assessed, and individual real-world cases of drug efficacy were presented. Results. Objective response rates are comparable to those shown in large randomized trials. The median follow-up was 67 days; the 6-month overall survival was 70.1% (95% confidence interval [CI] 49.4–99.6%), and the 6-month progression-free survival was 52.1% (95% CI 29.9–90.6%). There were no significant complications associated with therapy; in particular, no events of interstitial lung disease were reported. Discussion. The real-world efficacy of trastuzumab deruxtecan was comparable to that in randomized clinical trials. However, at the level of individual clinical cases, slightly lower efficacy was noted in initially frailer patients (ECOG score 3). Also, it should be noted that the study included patients who had the opportunity to purchase an expensive drug and, therefore, had a social status different from the general population, which could affect the results of this study. Conclusion. The use of trastuzumab deruxtecan in real-world settings has demonstrated high efficacy and a good safety profile.