As we did not follow up with the loss of B7H6 expression on melanoma cells isolated ex vivo from a relapsed NSG mouse treated with NKp30-CD28 CAR TCRKO T therapy, we can only speculate that the appearance of a B7H6 negative melanoma clone was possibly due to dysfunctional transcriptional/post-transcriptional control mechanism described or metalloproteinase-mediated shedding. Here, CD28 is linked to melanoma.