Research ArticlePain

Anti–PD-1 treatment impairs opioid antinociception in rodents and nonhuman primates

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Science Translational Medicine  19 Feb 2020:
Vol. 12, Issue 531, eaaw6471
DOI: 10.1126/scitranslmed.aaw6471

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A checkpoint for pain

Immune checkpoint blockade therapies using antibodies against programmed cell death protein–1 (PD-1) have been shown encouraging results for treating several tumors. Opioid treatment is frequently administered to patients with cancer for controlling disease-associated pain. PD-1 is expressed in sensory neurons and mediates pain sensitivity in mice. Now, Wang et al. studied the relationship between PD-1 expression and opioid effects in mice and nonhuman primates (NHPs). Morphine analgesic effect was diminished after PD-1 inhibition, and PD-1 blockade increased opioid-induced hyperalgesia in mice. In NHPs, immunotherapy targeting PD-1 inhibited morphine-induced antinociception. The results suggest that immunotherapies targeting PD-1 might reduce the sensitivity to opioids.


Emerging immunotherapies with monoclonal antibodies against programmed cell death protein–1 (PD-1) have shown success in treating cancers. However, PD-1 signaling in neurons is largely unknown. We recently reported that dorsal root ganglion (DRG) primary sensory neurons express PD-1 and activation of PD-1 inhibits neuronal excitability and pain. Opioids are mainstay treatments for cancer pain, and morphine produces antinociception via mu opioid receptor (MOR). Here, we report that morphine antinociception and MOR signaling require neuronal PD-1. Morphine-induced antinociception after systemic or intrathecal injection was compromised in Pd1−/− mice. Morphine antinociception was also diminished in wild-type mice after intravenous or intrathecal administration of nivolumab, a clinically used anti–PD-1 monoclonal antibody. In mouse models of inflammatory, neuropathic, and cancer pain, spinal morphine antinociception was compromised in Pd1−/− mice. MOR and PD-1 are coexpressed in sensory neurons and their axons in mouse and human DRG tissues. Morphine produced antinociception by (i) suppressing calcium currents in DRG neurons, (ii) suppressing excitatory synaptic transmission, and (iii) inducing outward currents in spinal cord neurons; all of these actions were impaired by PD-1 blockade in mice. Loss of PD-1 also enhanced opioid-induced hyperalgesia and tolerance and potentiates opioid-induced microgliosis and long-term potentiation in the spinal cord in mice. Last, intrathecal infusion of nivolumab inhibited intrathecal morphine-induced antinociception in nonhuman primates. Our findings demonstrate that PD-1 regulates opioid receptor signaling in nociceptive neurons, leading to altered opioid-induced antinociception in rodents and nonhuman primates.

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