Background Toxicity of oncology treatments in real-life patients is frequently disregarded and hence underreported. Objective To characterize adverse events (AEs) of immunotherapy and targeted therapy reported in patients with locally advanced or metastatic melanoma. Setting District Hospital for Cancer treatment (Instituto Português de Oncologia de Lisboa Francisco Gentil). Method A retrospective cohort of melanoma patients was established, comprising adult patients diagnosed with malignant melanoma treated with immunotherapy or targeted therapy. Exposure was characterized by nature, time and intensity of exposure. To account for different exposure periods, person-time was used as unit of analysis. Main outcomes measure Occurrence of AEs. Results Data from 111 patients included in the cohort indicates the majority received immunotherapy regimens (CTLA-4, anti-PD-1 and combination therapy; (n = 70; 63.1%), among which anti-PD-1 were the predominant treatment. Pembrolizumab was the most frequently prescribed drug (n = 30; 45.7%). Three hundred and seventy-one AEs were extracted. The incidence of AEs was lower in the anti-PD-1 mAc group (54 AEs per 1000 person.months) and the number of AEs/patient was also lower (3.1 ± 2.0). Grade 3 to 4 AEs occurred in 15.3% (n = 17) of the cohort, being more common in the targeted therapy group. Forty-two (11.6%) of the extracted AEs were not described in the Summary of Product Characteristics of the drugs under study. Conclusion This study suggests various known and unknown AEs of immunotherapy and targeted therapy may be identified using the Cancer Registry database. These events should be considered as signals worth further investigation for assessment of causality as the underreporting of AEs in cancer may have potential implications for the patient's quality of life.
Keywords: Adverse drug reactions; Adverse events; Drug-related side effects and adverse reactions; Immunotherapy; Malignant melanoma; Pharmacovigilance.