Evaluation of ABT-751 against childhood cancer models in vivo.
OBJECTIVE
ABT-751 is a novel antimitotic agent that binds tubulin at the colchicine binding site. ABT-751 is undergoing Phase I trials in children, but has not been evaluated against a range of pediatric tumor models in vivo.


METHODS
ABT-751 was evaluated against 27 subcutaneously implanted xenograft models of childhood cancer including neuroblastoma [4], osteosarcoma [4], Ewing sarcoma [2] rhabdomyosarcoma [8], medulloblastoma [1] and eight kidney cancer lines (six Wilms tumors, two rhabdoid). ABT-751 was administered at 100 mg/kg P.O. on a schedule of 5 days on, 5 days off, 5 days on, repeating the cycle at 21 days. Tumor diameters were measured at 7 day intervals for a period of 12 weeks. Three measures of antitumor activity were used: (1) clinical response criteria [e.g., partial response (PR), complete response (CR), etc.]; (2) treated to control (T/C) tumor volume at day 21; and (3) a time to event measure based on the median event free survival (EFS) of treated and control lines.


RESULTS
ABT-751 induced regression in 4 of 25 models (16%) including models of neuroblastoma that are refractory to vincristine and paclitaxel. Other regressions occurred in rhabdomyosarcoma and Wilms tumor models. ABT-751 significantly increased event free survival (EFS > 2.0) in eight models (33%) in addition to those with objective responses.


CONCLUSIONS
ABT-751 demonstrated intermediate activity against this tumor panel. Neuroblastoma models appear somewhat more sensitive to this agent, with objective regressions also in rhabdomyosarcoma and Wilms tumor. ABT-751 was also active in several tumor lines intrinsically refractory to vincristine or paclitaxel.
Morton
Christopher L
CL
Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 North Lauderdale St, Memphis, TN 38105, USA.
Favours
Edward G
EG
Mercer
Kimberly S
KS
Boltz
Claire R
CR
Crumpton
Jeri Carol
JC
Tucker
Chandra
C
Billups
Catherine A
CA
Houghton
Peter J
PJ
D000818:Animals; D050256:Antimitotic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D002648:Child; D005260:Female; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D009374:Neoplasms, Experimental / Q000188:drug therapy*; D010372:Pediatrics; D013449:Sulfonamides / Q000008:administration & dosage / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
C490492:ABT751; D050256:Antimitotic Agents; D013449:Sulfonamides