Efficacy and safety of fentanyl inhalant for the treatment of breakthrough cancer pain: a multicenter, randomized, double-blind, placebo-controlled trial.

Background: Breakthrough cancer pain (BTcP) has a negative impact on patients' quality of life, general activities, and is related to worse clinical outcomes. Fentanyl inhalant is a hand-held combination drug-device delivery system providing rapid, multi-dose (25μg/dose) administration of fentanyl via inhalation of a thermally generated aerosol. This multicenter, randomized, placebo-controlled, multiple-crossover, double-blind study evaluated the efficacy, safety, and tolerability of fentanyl inhalant in treating BTcP in opioid-tolerant patients.

Methods: The trial was conducted in opioid-tolerant cancer patients with 1 ~ 4 BTcP outbursts per day. Each patient was treated and observed for 6 episodes of BTcP (4 with fentanyl inhalant, 2 with placebo). During each episode of targeted BTcP, patients were allowed up to six inhalations, with an interval of at least 4 min between doses. Primary outcome was the time-weighted sum of PID (pain intensity difference) scores at 30 min (SPID30).

Results: A total of 335 BTcP episodes in 59 patients were treated. The mean SPID30 was -97.4 ± 48.43 for fentanyl inhalant-treated episodes, and -64.6 ± 40.25 for placebo-treated episodes (p < 0.001). Significant differences in PID for episodes treated with fentanyl inhalant versus placebo was seen as early as 4 min and maintained for up to 60 min. The percentage of episodes reported PI (pain intensity) scores ≤ 3, a ≥ 33% or ≥ 50% reduction in PI scores at 30 min, PR30 (pain relief scores at 30 min) and SPID60 favored fentanyl inhalant over placebo. Only 4.4% of BTcP episodes required rescue medication in fentanyl inhalant group. Most AEs were of mild or moderate severity and typical of opioid drugs.

Conclusion: Treatment with fentanyl inhalant was shown to be a promising therapeutic option for BTcP, with significant pain relief starting very soon after dosing. Confirmation of effectiveness requires a larger phase III trial.

Trial registration: ClinicalTrials.gov: NCT05531422 registered on 6 September 2022 after major amendment, NCT04713189 registered on 14 January 2021.