Olanzapine vs fosaprepitant: Which is better for CINV prevention?

Olanzapine appears to be just as effective as fosaprepitant, a neurokinin-1 receptor antagonist (NK1-RA), in controlling chemotherapy-induced nausea and vomiting (CINV) in patients with gynaecologic malignancies who were receiving carboplatin/paclitaxel chemotherapy every 3 weeks, a prospective study presented at SGO 2024 suggests. However, the former trumps the latter in terms of cost effectiveness.

Fifty-eight percent of olanzapine-treated participants experienced a complete response (CR) 0–120 hours post-chemotherapy. The investigators defined CR as no emesis and no need for rescue medications. In the fosaprepitant arm, the corresponding percentage of participants who achieved CR was 40 percent. Despite the numerical difference, it did not achieve statistical significance (p=0.2).

This trend was similarly seen during the acute (0–24 hours after chemotherapy; 92 percent vs 72 percent; p=0.08) and delayed time periods (>24 to 120 hours after chemotherapy; 58 percent vs 48 percent; p=0.47). [SGO 2024, poster ID 2290]

There were also no differences in the rates of no nausea between the olanzapine and the fosaprepitant arms overall (25 percent vs 28 percent; p=0.81) and during the acute (79 percent vs 60 percent; p=0.15) and delayed time periods (33 percent vs 32 percent; p=0.92).

“Both regimens were well-tolerated, with few adverse events,” the researchers noted. There were only two olanzapine-treated patients and one fosaprepitant recipient who reported grade 3 fatigue that was potentially related to the study drug.

Of note was the cost differential per cycle between the olanzapine and fosaprepitant arms, with the former being substantially cheaper than the latter ($0.24 vs 61.32).

Eligible participants for this study were individuals who had a known diagnosis of a gynaecologic malignancy, were aged between 18 and 90 years, and have not had chemotherapy over the last 12 months. A total of 59 patients (49 evaluable) were randomized between January 2021 and August 2023 to receive either oral olanzapine 5 mg on days 1–4 or IV fosaprepitant on day 1.

Participants in both treatment arms were also administered IV dexamethasone 20 mg on day 1 and ondansetron 8 mg IV or 16 mg PO on day 1, then 8 mg PO BID on days 2–4 after chemotherapy. Rescue medication (ie, oral compazine 5–10 mg Q6H) was given on days 1–5 if needed.

Proposed algorithm for CINV prophylaxis

In the proposed algorithm for CINV prophylaxis for carboplatin AUC ≥4, the initial regimen comprised olanzapine (days 1–4), IV dexamethasone (day 1), and ondansetron (days 1–4).

If CINV is inadequately controlled, an IV NK1-RA was added to the prophylactic regimen on day 1. “If the nausea and vomiting was only delayed, [patients were advised to consider] extending olanzapine to 7 days first,” the researchers noted in their poster presentation.

If there was still inadequate control of CINV, participants were to add oral dexamethasone to their regimen on days 2 and 3.

Takeaway

“[Taken together,] given the similar efficacy and cost-saving implications, primary utilization of olanzapine, rather than a NK1-RA [such as fosaprepitant], as part of a prophylactic anti-emetic regimen should be considered,” the researchers concluded.