CTLA4 and melanoma: synthesized a P‐peptide using Fmoc‐protected d‐amino acids to target and disrupt the function of PD‐L1 in tumor cells.[101] In addition to PD‐1 and PD‐L1, the immune checkpoint inhibitor targeting CTLA‐4 also exhibits some radiosensitization effects in patients with melanoma and non‐small‐cell lung cancer.[102] A synthetic peptide that binds to the CTLA‐4 protein to block the contact of the CTLA‐4 receptor with B7‐1 has also been reported.[103]