Several cancers are highly refractory to conventional chemotherapy. The survival 
of tumors in several cases is assisted by checkpoint immunomodulation to 
maintain the imbalance between immune surveillance and cancer cell 
proliferation. Check point antibody inhibitors, such as anti-PD-1/PD-L1, are a 
novel class of inhibitors that function as a tumor suppressing factor via 
modulation of immune cell-tumor cell interaction. These checkpoint blockers are 
rapidly becoming a highly promising cancer therapeutic approach that yields 
remarkable antitumor responses with limited side effects. In recent times, more 
than four check point antibody inhibitors have been commercialized for targeting 
PD-1, PDL-1, and CTLA-4. Despite the huge success and efficacy of the anti-PD 
therapy response, it is limited to specific types of cancers, which attributes 
to the insufficient and heterogeneous expression of PD-1 in the tumor 
microenvironment. Herein, we review the current landscape of the PD-1/PD-L1 
mechanistic role in tumor immune evasion and therapeutic outcome for cancer 
treatment. We also review the current progress in clinical trials, combination 
of drug therapy with immunotherapy, safety, and future of check point inhibitors 
for multiple types of cancer.