Comparing the Efficacy of Fosnetupitant, an NK1 Receptor Antagonist in CDDP-Based Regimens, with That of Fosaprepitant and Aprepitant: A Retrospective Observational Study

Existing antiemetic therapy against emetic-risk agents across malignancies 24 h post-dose in the acute period in cisplatin (CDDP)-based regimens yields a satisfactory complete response (CR) rate of ≥90%. However, the control rate after 24 h in the delayed period is unsatisfactory. This study compared the efficacy of fosnetupitant (F-NTP), a neurokinin 1 receptor antagonist, with that of fosaprepitant (F-APR) and aprepitant (APR) in the treatment of patients with cancer at high emetic risk due to chemotherapy. In this retrospective case-control study involving patients receiving cisplatin-containing regimens and neurokinin 1 receptor antagonists, patients were divided into three groups based on prophylactic antiemetic therapy: F-NTP, F-APR, and APR. The CR rate was evaluated for each period up to 168 h and further subdivided into acute (0-24 h), delayed (24-120 h), overall (0-120 h), and beyond-delayed (120-168 h) periods. Eighty-eight patients were included in the F-NTP group, 66 in the F-APR group, and 268 in the APR group. The CR rates at 0-168 and 120-168 h after cisplatin administration were significantly higher in the F-NTP group than in the F-APR and APR groups. After adjusting for confounding factors, F-NTP use was an independent factor in the multivariate analysis. Prophylactic antiemetic therapy, including F-NTP, was effective and well-tolerated during the delayed period. The efficacy of F-NTP in managing chemotherapy-induced nausea and vomiting was superior to those of F-APR and APR during the study period.

Challenges in the Development of Intravenous Neurokinin-1 Receptor Antagonists: Results of a Safety and Pharmacokinetics Dose-Finding, Phase 1 Study of Intravenous Fosnetupitant

Oral NEPA is the fixed-combination antiemetic comprising netupitant (neurokinin-1 receptor antagonist [NK₁ RA]) and palonosetron (5-hydroxytryptamine-3 receptor antagonist [5-HT₃ RA]). Intravenous (IV) NEPA, containing fosnetupitant, a water-soluble N-phosphoryloxymethyl prodrug of netupitant, has been developed. Fosnetupitant does not require excipients or solubility enhancers often used to increase IV NK₁ RA water solubility, preventing the occurrence of hypersensitivity and infusion-site reactions associated with these products. In this phase 1 study, subjects received a 30-minute placebo or fosnetupitant (17.6-353 mg) infusion and an oral NEPA or placebo capsule, with 2-sequence crossover treatment for fosnetupitant 118- to 353-mg dose cohorts. IV fosnetupitant safety and pharmacokinetics were evaluated, and its equivalence to an oral netupitant 300-mg dose was defined. Overall, 158 healthy volunteers were enrolled. All adverse events (AEs) were mild or moderate in intensity. Doppler-identified infusion-site asymptomatic thrombosis occurred in 5.4% (fosnetupitant) and 1.2% (oral NEPA) of subjects. The frequency or number of treatment-related AEs did not increase with ascending fosnetupitant doses. The most common treatment-related AEs were headache (fosnetupitant, 8.1%; oral NEPA, 12.7%) and constipation (fosnetupitant, 1.4%; oral NEPA, 7.5%). A fosnetupitant 235-mg dose was equivalent, in terms of netupitant exposure, to 300-mg oral netupitant. The safety profile of a single fosnetupitant 235-mg infusion was similar to that of single-dose oral NEPA.

Multicenter, placebo-controlled, double-blind, randomized study of fosnetupitant in combination with palonosetron for the prevention of chemotherapy-induced nausea and vomiting in patients receiving highly emetogenic chemotherapy

Background

The current randomized, double‐blind, phase 2 study assessed the efficacy and safety profile of a single intravenous administration of fosnetupitant, a neurokinin 1 receptor antagonist prodrug, for the prevention of chemotherapy‐induced nausea and vomiting in Japanese patients receiving cisplatin‐based chemotherapy.

Methods

Patients scheduled to receive cisplatin (at a dose of ≥70 mg/m²)‐based regimens were randomly assigned to receive fosnetupitant at a dose of 81 mg or 235 mg or placebo in combination with palonosetron at a dose of 0.75 mg and dexamethasone. The primary endpoint was complete response (CR; no vomiting and no rescue medication) during the overall phase (0‐120 hours). The overall CR rate was compared between each dose of fosnetupitant and the placebo group adjusting for the stratification factors of sex and age class (age <55 years vs age ≥55 years). Safety was assessed, with special attention given to events that potentially were suggestive of infusion site reactions.

Results

A total of 594 patients were randomized. Of these, 194 patients, 195 patients, and 195 patients, respectively, in the placebo and fosnetupitant 81‐mg and 235‐mg dose groups were evaluable for efficacy. The overall CR rate was 54.7% for the placebo group, 63.8% for the fosnetupitant 81‐mg dose group (adjusted difference, 9.1%; 95% CI, ‐0.4% to 18.6% [P = .061]), and 76.8% for the fosnetupitant 235‐mg dose group (adjusted difference, 22.0%; 97.5% CI, 11.7% to 32.3% [P < .001]). Safety profiles were comparable between the 3 groups. The incidence of infusion site reactions related to fosnetupitant was ≤1% in each dose group.

Conclusions

Fosnetupitant at a dose of 235 mg provided superior prevention of chemotherapy‐induced nausea and vomiting among patients receiving cisplatin‐based chemotherapy compared with the control group, and with a satisfactory safety profile.

Fosnetupitant at a dose of 235 mg combined with palonosetron and dexamethasone was demonstrated to be effective in the prevention of emesis during the first 0 to 120 hours after the administration of cisplatin. The results of the current study suggest that fosnetupitant at a dose of 235 mg also may improve the percentage of patients with no nausea in the delayed phase (24 ‐ 120 hours after cisplatin administration), which is an unmet medical need of patients with cancer who are receiving chemotherapy.