The objective of this study is to construct a noninvasive approach using radiolabbled peptide 68Ga-cPP-BCH PET/CT to detect the PD-L1 expression of tumor lesion in patients with lung cancer, melanoma and other solid tumor to identify patients benefiting from anti-PD-(L)1 treatment.

Inclusion Criteria:

1. Aged 18-75, male and female, with ECOG score of 0 or 1;
2. Subjects with lung cancer, melanoma, or other solid tumors scheduled for immunotherapy or combined immunotherapy;
3. underwent PD-L1 IHC examination before therapy;
4. The expected survival was more than 26 weeks;
5. Blood routine test, liver and kidney function meet the following standards: blood routine: WBC >= 4.0 x 10^9/L or neutrophil >= 1.5 x 10^9/:, PLT >= 100 x 10^9 / L, Hb >= 90g / L; Pt or APTT <= 1.5 upper limit of normal value; liver and kidney function: total bilirubin <= 1.5 x ULT (upper limit of normal value), ALT / AST <= 2.5 upper limit of normal value or <= 5 x ULT (subject with liver metastasis), ALP <= 2.5 upper limit of normal value (if bone metastasis or liver metastasis exists, ALP <= 4.5 upper limit of normal value); BUN <= 1.5 x ULT, SCR <= 1.5 x ULT;
6. According to RECIST1.1, there was at least one measurable target lesion;
7. Understand and sign informed consent voluntarily with good compliance.

Exclusion Criteria:

1. The function of liver and kidney was seriously abnormal;
2. Preparation for pregnant, pregnant and lactating women;
3. Inability to lie flat for half an hour;
4. Suffering from claustrophobia or other mental disorders;
5. Other researchers considered it unsuitable to participate in the trial.

patients with lung cancer, melanoma or other solid tumors scheduled for immunotherapy or combined immunotherapy; underwent PD-L1 IHC examination before therapy