Phase I dose finding studies of obatoclax (GX15-070), a small molecule pan-BCL-2 family antagonist, in patients with advanced solid tumors or lymphoma.
OBJECTIVE
Two phase I, single-agent studies were conducted to determine the dose and regimen of obatoclax, an antagonist of all BCL-2 antiapoptotic proteins, for evaluation in phase II trials. The two studies, GX001 and GX005, evaluated the safety and tolerability of weekly 1-hour and 3-hour infusions of obatoclax, respectively.


METHODS
Eligible patients in both studies were adults with solid tumor or lymphoma and performance status 0-1 for whom standard therapies were not appropriate. In the GX001 study an accelerated dose titration design was initially used with subsequent cohorts of three to six patients with 40% dose increments between levels. In the GX005 study three to six patients entered at each dose level with 40% dose increments between levels.


RESULTS
Thirty-five patients were enrolled in studies GX001 (n = 8) and GX005 (n = 27). Clinically significant central nervous system (CNS) toxicity was observed using the 1-hour infusion schedule. The obatoclax maximum tolerated dose (MTD) in GX001 was 1.25 mg/m(2) due to these infusional CNS events. The 3-hour infusion schedule studied in GX005 had improved tolerability, and the obatoclax MTD was 20 mg/m(2). One patient in GX005 with relapsed non-Hodgkin's lymphoma achieved partial response of 2 months' duration, and one patient with relapsed non-Hodgkin's lymphoma had stable disease for 18 months.


CONCLUSIONS
The 1-hour infusion schedule of obatoclax was associated with neuropsychiatric dose-limiting toxicities at relatively low doses (MTD, 1.25 mg/m(2)). The 3-hour i.v. infusion of obatoclax administered once weekly to patients with solid tumors was better tolerated (MTD, 20 mg/m(2)), and evidence of clinical activity was observed.
Lombardi Cancer Center, Georgetown Medical Center, 3800 Reservoir Road NW, Washington, DC 20007-2113, USA.
Jimmy J
JJ
Hwang
John
J
Kuruvilla
David
D
Mendelson
Michael J
MJ
Pishvaian
J F
JF
Deeken
Lillian L
LL
Siu
Mark S
MS
Berger
Jean
J
Viallet
John L
JL
Marshall
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D019540:Area Under Curve; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007211:Indoles; D008223:Lymphoma / Q000188:drug therapy*; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors; D011758:Pyrroles / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D012074:Remission Induction
D000970:Antineoplastic Agents; D007211:Indoles; D019253:Proto-Oncogene Proteins c-bcl-2; D011758:Pyrroles; C520962:obatoclax