The most common serious adverse reactions are adrenal insufficiency (1.4%), anaemia (1.4%), back pain (1.1%), colitis (1.1%), diarrhoea (1.1%), myocarditis (1.1%), pneumonia (1.1%), and urinary tract infection (1.1%).

The incidence of Grade 3-5 adverse reactions in patients with advanced (unresectable or metastatic) melanoma was 43% for Opdualag.

Immuno-related side effects: As with all immunotherapy, immune-related side effects can occur in any organ of the body, both during and after treatment. Immune-related side effects that affect more than one system in the body can occur simultaneously. Read more about side effects in the product information. All healthcare professionals who prescribe immunotherapy must be knowledgeable about treatment algorithms for immune-related side effects and how these are classified. Early identification and management of immune-related side effects is important, and patients receiving immunotherapy should be closely monitored both during and after treatment.

Other important warnings and precautions:

• Solid organ transplant rejection has been reported in patients treated with PD-1 inhibitors. Nivolumab combined with relatlimab may increase this risk, and the benefits versus the risk of organ rejection should be carefully considered in transplant recipients.
•  Haemophagocytic lymphohistiocytosis (HLH) has been observed with nivolumab as monotherapy, in combination with relatlimab, and with other agents, with a fatal event reported in some cases. Caution is advised, and if HLH is confirmed, treatment should be stopped, and HLH treatment initiated.
• In patients who have undergone allogeneic Haematopoietic Stem Cell Transplantation (HSCT), severe and rapid-onset graft-versus-host disease (GVHD), including fatal cases, have been reported, especially in those with a prior history of GVHD. 
• Nivolumab combined with relatlimab mayincrease the risk of severe GVHD and death in these patients. benefit-risk balance should be considered carefully.

Reference: 

1. Opdualag SmPC