Transient Worsening of Pain After Administration of Immune Checkpoint Inhibitors - A Case Series.

BACKGROUND/AIM: Transient pain enhancement or flare pain, is observed following the administration of immune checkpoint inhibitors (ICIs). However, the detailed mechanism of this phenomenon remains unclear. In this report, we present our experience of documenting the course of flare pain following ICI administration in six cases.

PATIENTS AND METHODS: Six patients with advanced solid tumors received ICI monotherapy between July 2017 and November 2019. Their pain increased within hours of ICI administration despite being stable before ICI administration. We evaluated the changes in the numerical rating scale (NRS) score over 72 h after ICI administration.

RESULTS: Four non-small cell lung cancer patients, one gastric cancer patient, and one renal cell cancer patient were included. Four patients experienced an increase in NRS, as evidenced by scores on two or more scales compared to the day before administration, whereas two patients showed an increase only on one scale. The NRS score decreased to almost the same level as that on the day before administration. Flare pain is observed in the same area as the primary site. Most of the pain was alleviated without the need for rescue analgesics, although one patient experienced a 4-point increase in the NRS scale.

CONCLUSION: Flare pain may occur following ICI administration. Healthcare providers should be aware of these events and provide patients with suitable information and coping techniques.