Granulocyte-macrophage colony-stimulating factor (GM-CSF) to increase efficacy of intensive sequential chemotherapy with etoposide, mitoxantrone and cytarabine (EMA) in previously treated acute myeloid leukemia: a multicenter randomized placebo-controlled trial (EMA91 Trial)

Efficacy and safety of gemtuzumab ozogamicin in patients with CD33-positive acute myeloid leukaemia in first relapse

Gemtuzumab ozogamicin (CMA-676, Mylotarg, an antibody-targeted chemotherapy agent, was recently approved by the FDA for the treatment of patients with CD33+ acute myeloid leukaemia (AML) in first relapse who are 60 years of age or older and who are not considered candidates for other types of cytotoxic chemotherapy. In combined Phase II studies of 142 patients with CD33+ AML in first relapse, gemtuzumab ozogamicin monotherapy was associated with a 30% overall response rate. While treated patients had relatively high incidences of myelosuppression, grade 3 or grade 4 hyperbilirubinaemia (23%) and elevated hepatic transaminases (17%), the incidences of grade 3 or grade 4 mucositis (4%) and infections (28%) were low compared with what might be expected in association with conventional chemotherapeutic treatment. In contrast with the usual in-patient administration of cytarabine and anthracycline-containing induction regimens, a large number of patients were treated with gemtuzumab ozogamicin as outpatients (38% and 41% for the first and second doses, respectively). Two prognostic factors for patients with AML in first relapse, age and duration of complete remission, had relatively little effect on response rates to gemtuzumab ozogamicin. Preliminary data in pediatric patients also suggest the immunoconjugate to be reasonably well tolerated. Studies of gemtuzumab ozogamicin in combination with anthracycline and cytarabine are underway. Gemtuzumab ozogamicin, administered to patients with CD33+ AML in first relapse, has shown overall response rates comparable to conventional agents and a safety profile that appears to be favourable.

Efficacy and safety of gemtuzumab ozogamicin in patients with CD33-positive acute myeloid leukemia in first relapse

PURPOSE

Three open-label, multicenter trials were conducted to evaluate the efficacy and safety of single-agent Mylotarg (gemtuzumab ozogamicin; CMA-676; Wyeth Laboratories, Philadelphia, PA), an antibody-targeted chemotherapy agent, in patients with CD33-positive acute myeloid leukemia (AML) in untreated first relapse.

PATIENTS AND METHODS

The study population comprised 142 patients with AML in first relapse with no history of an antecedent hematologic disorder and a median age of 61 years. All patients received Mylotarg as a 2-hour intravenous infusion, at a dose of 9 mg/m(2), at 2-week intervals for two doses. Patients were evaluated for remission, survival, and treatment-emergent adverse events.

RESULTS

Thirty percent of patients treated with Mylotarg obtained remission as characterized by 5% or less blasts in the marrow, recovery of neutrophils to at least 1,500/microL, and RBC and platelet transfusion independence. Although patients treated with Mylotarg had relatively high incidences of myelosuppression, grade 3 or 4 hyperbilirubinemia (23%), and elevated hepatic transaminase levels (17%), the incidences of grade 3 or 4 mucositis (4%) and infections (28%) were relatively low. There was a low incidence of severe nausea and vomiting (11%) and no treatment-related cardiotoxicity, cerebellar toxicity, or alopecia. Many patients received Mylotarg on an outpatient basis (38% and 41% of patients for the first and second doses, respectively). Among the 142 patients, the median total duration of hospitalization was 24 days; 16% of patients required 7 days of hospitalization or less.

CONCLUSION

Administration of the antibody-targeted chemotherapy agent Mylotarg to patients with CD33-positive AML in first relapse induces complete remissions with what appears to be a favorable safety profile.

Current Perspectives on the Use of Growth Factors in the Therapy of Acute Myeloid Leukaemia; Malignancy

Recombinant haematopoietic growth factors have been available for clinical use for over a decade, however their role in the management of patients with acute myeloid leukaemia (AML) has yet to be established. There are several potential roles for the use of growth factors in the management of patients with AML, including reduction in the infective complications associated with the underlying disease and its treatment, use as mobilising agents in stem cell transplantation and as priming agents with chemotherapy. Clinical trials have failed to give clear indications for the use of growth factors following chemotherapy, mainly due to the variability of patient populations, chemotherapy and growth factor schedules used. G-CSF appears to be associated with no negative impact on remission rate or survival but clear benefits in terms of infection-related endpoints were not universally seen. Three studies did show a reduction in duration of hospitalisation, particularly when G-CSF was used following consolidation chemotherapy and economic analyses have also shown financial advantages to the administration of G-CSF. GM-CSF had a variable impact on survival and only two studies demonstrated reduction in serious infections or antimicrobial therapy use. These trials also showed economic benefits for the use of GM-CSF. Clinical studies which have attempted to exploit possible potentiation of chemotherapeutic activity by recruitment of leukaemic cells into the cell cycle have generally been disappointing. Use of growth factors for this purpose, outside the context of randomised clinical trials cannot be recommended. GM-CSF may have a role in modulating the cellular immune response against cancer cells but experimental data on its activity against leukaemia cells is limited. Augmentation of white cell function by G-CSF or GM-CSF may also be of clinical benefit in patients with suspected or confirmed fungal infection and further trials are underway.