Low-dose interleukin-2 immunotherapy does not improve outcome of patients age 60 years and older with acute myeloid leukemia in first complete remission: Cancer and Leukemia Group B Study 9720.
OBJECTIVE
Cancer and Leukemia Group B (CALGB) 9720 evaluated subcutaneous low-dose recombinant interleukin-2 (rIL-2) maintenance immunotherapy as a strategy for prolonging remission in older patients with acute myeloid leukemia (AML).


METHODS
AML patients age 60 years and older in first complete remission after induction and consolidation chemotherapy were randomly assigned to no further therapy or a 90-day regimen of 14-day cycles of low-dose rIL-2, aimed at expanding natural killer (NK) cells, followed by 3-day higher doses aimed at activating cytotoxicity of expanded NK cells to lyse residual AML cells. All randomly assigned patients were included in an intention-to-treat analysis.


RESULTS
A total of 163 (64%) of 254 patients who completed induction and consolidation chemotherapy on CALGB 9720 were randomly assigned to rIL-2 (n = 81) or no further therapy (n = 82); the most common reasons for lack of random assignment were patient refusal and relapse. Fifteen patients randomly assigned to rIL-2 never initiated it because of refusal, intercurrent medical problems, or relapse, and 24 patients initiated rIL-2 but stopped early because of toxicity or relapse. Grade 4 toxicities during rIL-2 therapy included thrombocytopenia (65%) and neutropenia (64%), and grade 3 toxicities included anemia (33%), infection (24%) and malaise/fatigue (14%). Forty-two patients (52%) randomly assigned to rIL-2 completed the full 90-day course. Patients in both arms had similar distributions of both disease-free (combined median = 6.1 months; P = .47) and overall survival (combined median = 14.7 months; P = .61) after random assignment. Moreover, the 42 patients who completed all planned therapy did not show prolongation of disease-free or overall survival.


CONCLUSIONS
Low-dose rIL-2 maintenance immunotherapy is not a successful strategy in older AML patients.
Baer
Maria R
MR
University of Maryland Greenebaum Cancer Center, Baltimore, MD 21201, USA. mbaer@umm.edu
George
Stephen L
SL
Caligiuri
Michael A
MA
Sanford
Ben L
BL
Bothun
Sandra M
SM
Mrózek
Krzysztof
K
Kolitz
Jonathan E
JE
Powell
Bayard L
BL
Moore
Joseph O
JO
Stone
Richard M
RM
Anastasi
John
J
Bloomfield
Clara D
CD
Larson
Richard A
RA
D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D018572:Disease-Free Survival; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007167:Immunotherapy; D007376:Interleukin-2 / Q000627:therapeutic use*; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D012074:Remission Induction; D015996:Survival Rate; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D007376:Interleukin-2