Disproportionality Analysis of Pulmonary Adverse Events Associated with Trastuzumab Deruxtecan Using the Japanese Adverse Drug Event Report Database.

Aim: This study was conducted to examine disproportionality, times to onset, incidence rates, and outcomes of trastuzumab deruxtecan-associated pulmonary adverse events (AEs) using the Japanese Adverse Drug Event Report database.

Methods: We analyzed data for the period from April 2004 to December 2024. Data on pulmonary AEs were extracted, and the relative disproportionality of AEs was estimated using reporting odds ratios (RORs).

Results: Of the 3,221,393 reports analyzed, we identified 1561 reports of AEs associated with trastuzumab deruxtecan, including 505 pulmonary AEs. Only 474 reports were identified as signal-positive: interstitial lung disease, pulmonary toxicity, pneumonitis, and Pneumocystis jirovecii pneumonia. Among these, interstitial lung disease was the most frequently reported (26.6%) and included several fatal cases. Histograms of median times to onset for the four detected pulmonary AE signals showed that AEs occurred at a median of 7-27.5 days after trastuzumab deruxtecan administration. Weibull distributions showed that interstitial lung disease occurred early after administration (early failure type), but pulmonary toxicity occurred constantly throughout the exposure period (random failure type).

Conclusions: We focused on pulmonary AEs associated with trastuzumab deruxtecan as postmarketing AEs. Serious outcomes can arise after trastuzumab deruxtecan administration. Patients should be monitored for signs of onset of these AEs not only at the start of administration but also over an extended period.