Evaluation of factors contributing to the response to fosaprepitant in a heterogeneous, moderately emetogenic chemotherapy population: an exploratory analysis of a randomized phase III trial

Purpose Fosaprepitant improved prevention of chemotherapy-induced nausea and vomiting (CINV) in a randomized, double-blind phase III trial (PN031). This post hoc analysis explored factors that may have influenced response. Methods Adult subjects ( N = 1000) scheduled to receive non-anthracycline and cyclophosphamide (AC) moderately emetogenic chemotherapy (MEC) on day 1 were randomly assigned 1:1 to a single-dose, 150-mg intravenous fosaprepitant regimen or a control regimen. Both regimens included dexamethasone and ondansetron on day 1, with ondansetron continuing through day 3 in the control arm only. Complete response (CR; no vomiting and no rescue medication) rates in the acute, delayed, and overall phases (0–25, 25–120, and 0–120 h, respectively) were analyzed by chemotherapy type (carboplatin-based vs non-carboplatin-based), chemotherapy duration (single-day vs multiple-day), and baseline characteristics. Results Most subjects received single-day chemotherapeutic regimens (70.6%), which were mainly carboplatin-based (67.6%). CR with fosaprepitant was consistent (76–80%) during the delayed and overall phases in carboplatin-based and non-carboplatin-based subgroups and in subgroups receiving single-day or multiple-day MEC regimens. Treatment effects favored fosaprepitant for the carboplatin-based versus the non-carboplatin-based group during the delayed phase (14.1 vs 6.5%; p = 0.06), and for the single-day versus the multiple-day subgroup during the delayed (13.2 vs 3.2%; p = 0.02) and overall phases (12.8 vs 4.0%; p = 0.06). Conclusions This exploratory analysis confirms that single-dose fosaprepitant is effective for the prevention of CINV in subjects receiving carboplatin or non-carboplatin in both single- and multiple-day non-AC MEC chemotherapy regimens. This trial is registered at ClinicalTrials.gov , number NCT01594749.