AbataCept for the Treatment of Immune-cHeckpoint Inhibitors Induced mYocarditiS

Immune-checkpoint-inhibitors (ICI) have revolutionized treatment for about 20 cancer types. They unleash anti-tumor immune responses. Unfortunately, in 0.36-1.23% of patients, this activation can also lead to lethal immune-related adverse events (irAEs) that can affect any organ. Among those irAEs, ICI-induced myocarditis was the most frequently fatal with death rate reaching 50% in a large case-series of over 100 patients. This study is a dose-finding Phase II trial where 3 abatacept IV regimen (A-10 mg/kg; B-20 mg/kg and C-25 mg/kg at Day0, Day5+/-2, Day14+/-2) will be tested aiming at reaching promptly (after the first dose) and sustainably a CD86RO≥80% during the first 3 weeks of ICI-myocarditis management. The main objective is to find the lowest dose required to achieve a circulating monocytes CD86RO≥80% within the first week of treatment and sustainably over three weeks. The target population is all adult patients with cancer (all cancer types) treated by immune checkpoint inhibitors (anti-PD1, anti-PDL1, anti-CTLA4 monotherapies or combination) and presenting drug-induced myocarditis.

Inclusion Criteria: 1. Age ≥ 18 years old 2. Weight ≥ 40 kg and ≤ 125 kg 3. Patients treated with ICI immunotherapy (monotherapy or combination), including anti-PD1, anti-PDL1, anti-CTLA4; and including any type of cancer (even those in which ICI is not currently approved by regulatory) 4. Definite, probable or possible ICI-induced myocarditis according to the diagnostic criteria of the most recent expert consensus recommendations (e.g27, to be updated with any new recommendations to be published) 5. Severe or corticosteroid-resistant ICI-myocarditis: * Severe ICI-myocarditis is defined either 1/ by the appearance of an alteration of the LVEF\