Combined addition of anti-CTLA4 and anti-PDL1 mAbs to LTT cultures of SJS/TEN (2 CBZ and 2 SMX) and DRESS (4 CBZ) increased drug-induced proliferation index, even turning some negative LTT into positive LTT (4 out of 8; 50%). Here, CD274 is linked to toxic epidermal necrolysis.