PDCD1 and bone cancer: In addition, CCL2 directly activated CCR2-expressing DRG nociceptors, as evidenced by attenuated bone cancer pain after systemic administration of the CCR2 antagonist RS504393.89 Given that anti-PD-1 therapies are already used clinically in patients with various cancers, this may be an attractive new therapeutic option for patients with primary or metastatic bone cancer that could aid in pain control and bone destruction.