SAN ANTONIO —
Although it’s highly effective in combination with standard antiemetic therapy, olanzapine at the standard dose of 10 mg makes people too drowsy. “This has prevented its widespread use in clinical practice,” medical oncologist Jyoti Bajpai, DM, of Tata Memorial Cancer Centre, Mumbai, India, explained at the San Antonio Breast Cancer Symposium.
She and her colleagues had a simple idea: Reduce the dose to 2.5 mg instead of 10 mg to prevent the problem. In a randomized trial with 267 patients that Dr. Bajpai presented at the meeting, they found that the lower dose was just as effective for nausea and vomiting prophylaxis, and it greatly reduced daytime somnolence.
“This merits consideration as an antiemetic regimen of choice for highly emetogenic chemotherapy.” The findings are “practice changing,” Dr. Bajpai, the lead investigator, said.
Laura Huppert, MD, a breast oncologist at the University of California, San Francisco, wasn’t surprised by the finding.
She said she and her colleagues at UCSF use a lot of olanzapine for nausea and vomiting prophylaxis. Like the team in India, they have found that 2.5 mg is effective and causes far less sleepiness. Some patients require 5 mg, but the full 10-mg dose is rarely needed.
Although the approach is familiar at UCSF, Dr. Huppert said she doesn’t think a lot of oncologists outside of academic centers know that olanzapine is “really helpful” and that “you don’t need a high dose.” It’s “a very good clinical pearl” and “definitely a new message for some,” she said in an interview.
Over 90% of the subjects in the study were women with breast cancer. Other cancers included sarcoma, germ cell tumors, and head and neck cancer. Subjects were scheduled for their first chemotherapy session with anthracycline-cyclophosphamide and high-dose cisplatin.
The trial randomized 135 patients to 10 mg of olanzapine and 132 to 2.5mg for 5 days, starting the day of their session. They were also on standard triple-antiemetic therapy (selective serotonin receptor (5-HT3) antagonist, neurokinin-1 receptor antagonist, and single-dose dexamethasone).
There were no significant differences between the two arms regarding nausea and vomiting, which patients tracked in daily journals using symptom severity and visual analog scales.
For instance, 44.7% in the 2.5-mg arm and 43.7% in the 10-mg arm reported no vomiting, no use of rescue medications, and no or only mild nausea (P = .87). Results were similar in the first 24 hours as well as on subsequent days.
There was also no difference in the proportion of patients who did have an emetic episode or needed rescue medication: 49.2% in the 2.5-mg arm versus 48.9% with 10 mg (P = .954).
Where the two groups split was on the incidence of daytime somnolence, which was reported by 65.2% of patients in the low-dose arm but 89.6% in the standard-dose group (P < .001). During the first 24 hours, 4.5% of low-dose patients reported severe somnolence versus 40% with 10-mg dosing (P < .001).
The overall incidence declined over the remaining study days, but the differences between the two groups were comparable. On day 5, for instance, 0.8% of low-dose patients but 8.1% of standard-dose patients reported severe somnolence (P = .004).
Low-dose patients also reported less appetite suppression.
The work was supported by the Progressive Ladies Welfare Association. Dr. Bajpai didn’t have any disclosures. Dr. Huppert is an adviser for AstraZeneca.