Fewer Therapy Delays with Palonosetron than with Similar Antiemetics

October 2012, Vol 3, No 7

San Francisco, CA—An analysis of a large claims database showed that patients with breast cancer had fewer delays in chemotherapy and maintained better adherence to their regimens when treated with the 5-hydroxy­tryptamine 3 (5-HT3) receptor an­­tagonist palonosetron (Aloxi) than with other agents in this antiemetic class.

“The 5-HT3 receptor antagonists have proven to effectively prevent and manage CINV [chemotherapy-induced nausea and vomiting], with palonosetron found to significantly lower CINV risk relative to other 5-HT3 drugs,” reported Hope Rugo, MD, Professor of Medicine, University of California, San Francisco School of Medicine, and colleagues in a poster presentation. “However, little evidence exists regarding the impact of these drugs on chemotherapy adherence and preventing delayed therapy."

Among patients treated with highly emetogenic chemotherapy (HEC), palo­­nosetron was associated with a >30% reduction in the frequency of treatment delays related to CINV. The difference increased to >60% for patients receiving moderately emetogenic chemotherapy (MEC).

The study also confirmed the previously reported higher efficacy of palonosetron versus other 5-HT3 receptor antagonists for preventing episodes of CINV, as reported at the 2012 Breast Cancer Symposium.

The team analyzed records in the HealthCore Integrated Research Database. Using National Compre­hensive Cancer Network (NCCN) treatment guidelines, they searched the database for patients with early breast cancer who had claims for HEC or MEC regimens between January 2002 and October 2010.

Emetogenic drugs included in the search were cyclophosphamide, doxorubicin, epirubicin, and carboplatin. HEC was defined as any regimen containing ≥1 HEC drug or containing ≥2 MEC drugs.

Claims related to the targeted chemo­therapeutic regimens and agents were then cross-referenced with claims for 5-HT3 antagonists.

NCCN-recommended treatment cycles and rest periods were determined for each patient’s chemotherapy regimen, and the chemotherapy dose per cycle was calculated.

Dr Rugo and colleagues separated patients into 2 cohorts: palonosetron (all patients treated only with that agent) and “others” (those who received any other 5-HT3 antagonist).

Principal outcomes of interest were acute or delayed CINV, delayed therapy (lasting twice the “permissible gap” between cycles for the specific regimen), and adherence (receiving the requisite number of chemotherapy cycles within the recommended time frame).

The search revealed 4885 patients treated with HEC regimens: 1782 who received palonosetron and 3103 who received other 5-HT3 antagonists. An­other 1378 patients received MEC regimens (682 in the palonosetron cohort and 696 in the “others” category).

In the HEC subgroup, 27.33% of the palonosetron cohort had ≥1 CINV event compared with 35.68% in the other cohort (P <.001). The rates of CINV in the MEC subgroups were 33.72% with palonosetron and 49.71% with other 5-HT3 antagonists (P <.001).

In general, the multivariate analysis confirmed the superiority of palono­setron, based on these data:

  • CINV (HEC): odds ratio (OR), 0.61; P <.001
  • CINV (MEC): OR, 0.51; P <.001
  • HEC therapy delay: OR, 0.75; P = .08
  • MEC therapy delay: OR, 0.37; P = .005
  • HEC adherence: OR, 1.1; P = .18
  • MEC adherence: OR, 1.29; P = .02.

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