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Preliminary Report of a Phase II Study of the Safety and Efficacy of Gemtuzumab Ozogamicin (Mylotarag)Given in Combination with Cytarabine in Patients with Acute Myelogenous Leukemia

Reviewer: Tracy d'Entremont, MD
OncoLink
Last Modified: December 7, 2002

Presenter: Michele Baccarani
Presenter's Affiliation: Ospedale S. Orsola; Bologna, Italy
Type of Session: Poster

Background

• Gemtuzumab has been approved in the United States for the treatment of patients aged sixty and above with CD33+ AML in first relapse for those patients without other cytotoxic options.
• A standard treatment approach for first line treatment of AML is cytarabine (ARA-C) in combination with an anthracycline.
• Standard anthracycline containing regimens cause severe mucositis and cardiac toxicity.
• This study was undertaken to combine gemtuzumab with ARA-C in patients over the age of sixty in order to decrease the cardiac toxicity and mucositis typically encountered with standard induction regimens.

Materials and Methods

• This was a Phase I/II study to evaluated the use of gemtuzumab in this setting
• The Phase 1 portion consisted of dose escalation in 21 patients with AML to determine the optimal dose level
• The Phase 2 study of 17 patients aged sixty or above with CD 33+ AML were given the combination of Mylotarg and ARA-C based on the Phase I results

Results

• Preliminary Results of 12 patients in the Phase II study were presented
• There were 5 CR (42%) CR was defined as: absence of blasts from peripheral blood, Less than 5% blasts in BM, BM biopsy with >20% cellularity, ANC > 1499, Plts > 99,999, Plt transfusion independence for > 1 wk
• There were 3 CRp (25%) CRp was defined as complete remission without platelet recovery
• The overall response rate (RR) of 8/12 (67%)
• The NCI grade 3/4 toxicities were as follows: Fever, Hypertension, Infection, AST/ALT rise (transient and reversible) each with 1 patient out of 12
• There were 2 deaths during treatment 1 for disease progression 1 for multi-organ failure

Author's Conclusions

• The authors conclude that this combination regimen is an option for patients over the age of 59 with CD33+ AML.
• The RR of 67% is similar to that seen in other induction regimens
• The toxicity was better than standard induction chemotherapy without cardiac toxicity and with no high grade mucositis.

Clinical/Scientific Implications

These data are certainly intriguing as many patients with AML are over age 59 at the time of diagnosis. Further follow-up is needed in regards to Relapse-Free and Overall Survival before its use will be adopted in the clinic. Given the data that we have for Mylotarg in the refractory or relapsed AML setting, it would be surprising if this regimen is more successful than standard chemotherapy. However, in a situation where the toxicity of anthracyclines is too great, this may prove to be an option

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