Patients with acute myeloid leukemia and RAS mutations benefit most from postremission high-dose cytarabine: a Cancer and Leukemia Group B study.
OBJECTIVE
RAS mutations occur in 12% to 27% of patients with acute myeloid leukemia (AML) and enhance sensitivity to cytarabine in vitro. We examined whether RAS mutations impact response to cytarabine in vivo.


METHODS
One hundred eighty-five patients with AML achieving complete remission on Cancer and Leukemia Group B study 8525 and randomly assigned to one of three doses of cytarabine postremission were screened for RAS mutations. We assessed the impact of cytarabine dose on cumulative incidence of relapse (CIR) of patients with (mutRAS) and without (wild-type; wtRAS) RAS mutations.


RESULTS
Thirty-four patients (18%) had RAS mutations. With 12.9 years median follow-up, the 10-year CIR was similar for mutRAS and wtRAS patients (65% v 73%; P = .31). However, mutRAS patients receiving high-dose cytarabine consolidation (HDAC; 3 g/m(2) every 12 hours on days 1, 3, and 5 or 400 mg/m(2)/d x 5 days) had the lowest 10-year CIR, 45%, compared with 68% for wtRAS patients receiving HDAC and 80% and 100%, respectively, for wtRAS and mutRAS patients receiving low-dose cytarabine (LDAC; 100 mg/m(2)/d x 5 days; overall comparison, P < .001). Multivariable analysis revealed an interaction of cytarabine dose and RAS status (P = .06). After adjusting for this interaction and cytogenetics (core binding factor [CBF] AML v non-CBF AML), wtRAS patients receiving HDAC had lower relapse risk than wtRAS patients receiving LDAC (hazard ratio [HR] = 0.67; P = .04); however, mutRAS patients receiving HDAC had greater reduction in relapse risk (HR = 0.28; P = .002) compared with mutRAS patients treated with LDAC.


CONCLUSIONS
AML patients carrying mutRAS benefit from higher cytarabine doses more than wtRAS patients. This seems to be the first example of an activating oncogene mutation favorably modifying response to higher drug doses in AML.
Neubauer
Andreas
A
Department for Hematology, Oncology and Immunology, Philipps University, Marburg, Germany.
Maharry
Kati
K
Mrózek
Krzysztof
K
Thiede
Christian
C
Marcucci
Guido
G
Paschka
Peter
P
Mayer
Robert J
RJ
Larson
Richard A
RA
Liu
Edison T
ET
Bloomfield
Clara D
CD
D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D003561:Cytarabine / Q000008:administration & dosage*; D003630:Daunorubicin / Q000008:administration & dosage; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D007262:Infusions, Intravenous; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D016016:Proportional Hazards Models; D012074:Remission Induction; D018709:Statistics, Nonparametric; D015996:Survival Rate
D003561:Cytarabine; D003630:Daunorubicin