Background and Importance Immune-mediated reactions play a major role in immunotherapy, so it is important to monitor patients and follow-up to improve patient safety.

Aim and Objectives To describe a case of immune-mediated hepatitis secondary to the use of pembrolizumab and multidisciplinary intervention in its management.

Material and Methods An 81-year-old patient diagnosed with advanced amelanotic nodular melanoma, with lung and axillary metastasis. Data obtained from the digital medical record and from the chemotherapy electronic prescription program. Safety profile of pembrolizumab in its technical data sheet (TDS) and the literature reported cases of hepatobiliary disorders with pembrolizumab were reviewed.

Results The patient began treatment with pembrolizumab 200 mg/3weeks for metastatic disease. Prior to the third infusion, she reported regular general condition, asthenia and dysgeusia, with elevation of transaminases (aspartate-transaminase: 31U/L (1–32); alanine-transaminase: 130U/L (0–55)) and total bilirubin: 1.60 mg/dL (0.30–1.20), diagnosing grade 4 immune-mediated hepatitis.

Specialist contacted with the hospital pharmacist to confirm whether it was an adverse effect (AE) secondary to pembrolizumab. The pharmacist performed a review of the TDS and literature that confirmed the event (hepatitis is described as a frequent AE (≥ 1/100 to < 1/10)).

Treatment with pembrolizumab suspended and the patient required immunosuppressive treatment (pulses of methylprednisolone and mycophenolate-mofetil). A control CT-scan showed a decrease in the size of the metastases.

After 2 weeks, the patient was asymptomatic and had grade 1 immune-mediated hepatitis, so restarted treatment with immunotherapy, switching to nivolumab 240 mg twice weekly. Close monitoring of transaminases levels and maintenance of immunosuppressive treatment continued.

The suspected AE notified to the Spanish Pharmacovigilance System and a causal relationship between the drug and the AE established according to the Naranjo Algorithm, obtaining a score of 5, which establishes a probable relationship.

Immune-mediated hepatitis is an AE also described with nivolumab, which was well tolerated by the patient, which did not occur with pembrolizumab despite having a similar safety profile.

Conclusion and Relevance Close monitoring and follow-up of AEs associated with drugs is important, as the participation of the pharmacist in multidisciplinary teams, validating treatments and carrying out their monitoring. All of this contributes to an improvement in the management of AEs and in patient safety.

Conflict of Interest No conflict of interest.