Phase I study of temozolomide and laromustine (VNP40101M) in patients with relapsed or refractory leukemia.
OBJECTIVE
Although alkylators are known to be effective against some myeloid leukemias, resistance is often mediated via O6-alkylguanine-DNA alkyltransferase (AGT). Temozolomide's inhibition of AGT may sensitize leukemia cells to the novel alkylator laromustine. We conducted a phase I translational study to evaluate the toxicities and estimate the maximum tolerated dose (MTD) of laromustine when administered with temozolomide (TMZ) in patients with hematologic malignancies.


METHODS
TMZ was delivered twice daily for 5 doses followed by a single infusion of laromustine. The target TMZ dose was the dose that would reliably result in > 90% AGT depletion. Once the target TMZ dose was identified, the laromustine dose was escalated. A total of 35 patients with relapsed/refractory leukemia were treated.


RESULTS
Treatment with TMZ 300 mg for 5 doses resulted in > 90% depletion of AGT levels in 5 of 6 patients. The MTD of the combination was established at TMZ 1500 mg and laromustine 300 mg/m2. Three of the 7 patients assayed from cohort 1 achieved > 90% depletion of AGT activity (range, 77%-100% depletion; median, 88%). Five of 6 patients enrolled in cohort 2 achieved > 90% depletion of AGT activity (range, 92%-100% depletion; median, 93.5%). This established that the 300-mg dose of TMZ (1500 mg total) would be maintained in subsequent cohorts. The majority of adverse events were primarily hematologic, with infectious and pulmonary complications also noted. Three (9%) of the patients with previous refractory disease achieved a complete remission, and 5 (14%) of the patients achieved a morphologic, leukemia-free, but persistent hypocellular bone marrow status.


CONCLUSIONS
Laromustine in combination with TMZ is tolerable and manageable at doses that predictably suppress AGT. Reliable TMZ-induced inhibition of AGT was observed in doses that are clinically tolerable. Evidence of antitumor effect was observed with this combination, suggesting that further efficacy studies should be performed.
Rizzieri
David
D
Division of Cellular Therapy, Duke University, Durham, NC, USA. rizzi003@mc.duke.edu
LoRusso
Samantha
S
Tse
William
W
Khan
Khuda
K
Advani
Anjali
A
Moore
Joseph
J
Karsten
Verena
V
Cahill
Ann
A
Gerson
Stanton L
SL
D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage* / Q000009:adverse effects*; D003606:Dacarbazine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D005260:Female; D049669:History, 16th Century; D006801:Humans; D006834:Hydrazines / Q000008:administration & dosage / Q000009:adverse effects; D007938:Leukemia / Q000188:drug therapy*; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy*; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000037:antagonists & inhibitors / Q000187:drug effects; D013449:Sulfonamides / Q000008:administration & dosage / Q000009:adverse effects; D000077204:Temozolomide; D055815:Young Adult
D006834:Hydrazines; D013449:Sulfonamides; C483604:laromustine; D003606:Dacarbazine; D019853:O(6)-Methylguanine-DNA Methyltransferase; D000077204:Temozolomide