Time to Onset of Gemcitabine-induced Thrombotic Microangiopathy in a Japanese Population: A Case Series and Large-scale Pharmacovigilance Analysis

Background/Aim: Gemcitabine-induced thrombotic microangiopathy (G-TMA) is associated with a high mortality rate. However, owing to its low incidence, data on G-TMA remain limited. Therefore, a detailed review of G-TMA cases is critical to understand this adverse event. In addition, reviewing literature and pharmacovigilance analytics may be useful to characterise G-TMA. Here, time to onset of G-TMA was analysed based on available data. Patients and Methods: We collected data for a case of TMA following gemcitabine administration at the Tokyo Metropolitan Geriatric Hospital. We also reviewed the literature on G-TMA cases in Japan from April 2000 to March 2022 to provide a case series. Moreover, we performed time-to-onset analysis of G-TMA using the data from the Japanese Adverse Drug Event Report (JADER) database. Results: Our case involved a patient with pancreatic cancer who developed thrombotic thrombocytopenic purpura 13 months after starting gemcitabine treatment. From the literature reviewed, in 14 out of 17 cases, G-TMA occurred 5-8 months after treatment initiation. The analysis of data from the JADER database showed that the median time to onset of G-TMA was 161 days. Weibull shape parameter analysis showed that the pattern of onset of G-TMA represented a random failure. Conclusion: This study elucidated the time to onset of G-TMA in a Japanese population. Weibull shape parameter analysis showed that G-TMA may not necessarily develop in a dose-dependent manner. These results may be useful for monitoring G-TMA in the clinical setting.