Incidence and risk of fatal adverse events in cancer patients treated with HER2-targeted antibody-drug conjugates: a systematic review and meta-analysis of randomized controlled trials

Objective: Antibody-drug conjugates (ADCs) that target human epidermal growth factor receptor 2 (HER2) are leading a new era of targeted cancer therapy. These drugs have also been associated with several fatal adverse events, such as pneumonia, interstitial lung disease, and infection. We performed a meta-analysis of randomized controlled trials (RCTs) to estimate the incidence and risk of fatal adverse events in cancer patients treated with HER2-targeted ADCs.

Methods: We performed a systematic search in Embase, PubMed, Web of Science, and Scopus databases from inception to February 1, 2022, and the last search was updated to July 1, 2023. The eligible studies for inclusion in our analysis were limited to RCTs of HER2-targeted ADCs that were approved by the US Food and Drug Administration and examined on cancer patients with available data on fatal adverse events. The protocol for this study was registered in PROSPERO (No. CRD42022331627).

Results: Fifteen studies (13 RCTs) involving 7,277 patients were finally included for meta-analysis. Of these patients, 4,246 received HER2-targeted ADCs and 3,481 received the control treatment. The data were combined using Bayesian hierarchical modeling, which allowed for the estimation of the mean incidence of fatal adverse events to be 0.78% (95% CrI: 0.28-1.37%, τ = 0.006) for the patients treated with HER2-targeted ADCs. The relative risk was 0.80 (95% CrI, 0.5-1.26, τ = 0.17) compared to control patients. Among 43 reported deaths caused by HER2-targeted ADCs, the most common fatal adverse event was respiratory toxicity, including pneumonia, pneumonitis, and interstitial lung disease. On subgroup analysis, no difference in the risk of fatal adverse events was found between different HER2-targeted ADCs or cancer types.

Conclusion: Our findings suggest that the risk of fatal adverse events with HER2-targeted ADCs may be lower compared to standard control therapies in cancer patients, and there is no significant difference in risk observed between different HER2-targeted ADCs or cancer types. However, the most common fatal adverse event was respiratory toxicity, suggesting that cancer patients who use the above drugs should strengthen respiratory system monitoring and take preventive measures in some severe cases.