SAN FRANCISCOPatients receiving monoclonal antibody-targeted chemotherapy with gemtuzumab ozo-gamicin (Mylotarg) rather than conventional combination chemotherapy for first relapse of acute myelogenous leukemia (AML) are more likely to be treated as outpatients, resulting in considerable cost savings, according to a study from Fred Hutchinson Cancer Research Center and Wyeth-Ayerst Research.
An analysis of data from the pivotal study of gemtuzumab in 142 patients with AML in first relapse showed that outpatient care is as safe as inpatient delivery of the drug, Eric Sievers, MD, reported at the 42nd Annual Meeting of the American Society of Hematology (ASH).
"Clinical outcome was not significantly different among patients who were treated as outpatients vs those treated as inpatients," he told ONI. "So that led us to believe that, at least in terms of outcome, these two groups were the same."
Furthermore, comparison of the cost of gemtuzumab therapy with that of traditional combination chemotherapy showed gemtuzumab therapy to be significantly less expensive, despite the higher cost of the antibody.
Gemtuzumab received FDA approval last year for treatment of CD33-positive AML in patients age 60 and older who are in first relapse and are poor candidates for cytotoxic therapy. In the pivotal study, the administration setting was at the investigator’s discretion, said Dr. Sievers, assistant professor of pediatric hematology/oncology, University of Washington, and assistant member, Fred Hutchinson.
The outpatient-based program for administration of the antibody-targeted chemotherapy provided ambulatory support to patients from premedication through monitoring of count recovery, including inpatient or outpatient management of complications. Typically, patients stayed in the ambulatory setting while they were observed carefully; vital signs were monitored closely during and for at least 4 hours after the infusion.
The investigators found that 54 of 142 patients (38%) were treated as outpatients for the first dose of therapy; 61 (43%) were prehospitalized for the first dose, and 27 (19%) were hospitalized on the same day that the first dose was given. About two thirds (34 of 54 patients) who received the first dose as outpatients were also outpatients for the second dose.
As expected, the outpatient group spent fewer mean number of days in the hospital (38 days vs 46 days for preexisting hospitalization and 41 days for same-day hospitalization). The greatest savings occurred when one or both doses were received as an outpatient. There were minimal or no cost savings compared with conventional chemotherapy when patients were already hospitalized before initiation of treatment.
A control group for the gemtuzumab population was built from 12 published studies of 1,793 patients who received conventional AML chemotherapy, said Rajiv Mallick, PhD, director, Global Health Outcomes Assessment, Wyeth-Ayerst Research. "There are not that many studies in relapsed AML, so actually nine studies were of de novo patients. We had no hesitation in including them because our comparison will be conservative, since their prognosis is better," he said.
Among those patients receiving traditional chemotherapy, only 1% (19) were treated as outpatients, while 97% were hospitalized on the same day that chemotherapy was initiated. "Hospitalization is not a function of prognosis; it is a function of the treatment that patients got," Dr. Mallick commented.
A typical hospital stay for AML chemotherapy was associated with $1,700 in average daily costs. Assuming this daily cost for an average 31 days and incorporating wholesale drug acquisition costs ($11,700 for gemtuzumab and $3,800 for conventional treatment), expected global net cost savings with gemtuzumab equaled about $1,000 per patient.
This was due to a higher probability that gemtuzumab patients would receive outpatient therapy and spend fewer days in the hospital. These outpatient savings offset the higher drug costs.
US Subgroup Analysis
In a subgroup cost analysis of the gemtuzumab pivotal trial data, the researchers found that US patients were more likely to receive gemtuzumab on an outpatient basis than study patients in other countries, and their care was associated with fewer hospital days on average. Among US patients, 36% (28 of 78) received both doses as outpatients.
The subgroup analysis assumed $1,550 daily net cost of traditional chemotherapy during hospitalization and an expected cost of gemtuzumab therapy of $6,500 to $13,000, depending on whether patients received one or two doses. Based on these figures, the expected cost saving for US patients over the control patients was about $10,000 per patient, considerably higher than the savings seen in the base analysis.
As researchers develop a track record for gemtuzumab and physicians see that an outpatient approach can be successful, "I think the issue of cost savings will become even sharper, especially as far as US Medicare coverage is concerned," Dr. Mallick said.