Two consecutive phase II window trials of irinotecan alone or in combination with vincristine for the treatment of metastatic rhabdomyosarcoma: the Children's Oncology Group.
OBJECTIVE
To estimate the antitumor activity and toxicity of irinotecan alone and in combination with vincristine when administered as window therapy and in combination with standard chemotherapy in pediatric patients with newly diagnosed metastatic rhabdomyosarcoma.


METHODS
Nineteen patients younger than age 21 years with newly diagnosed metastatic rhabdomyosarcoma or undifferentiated sarcoma received window therapy with two cycles of irinotecan (20 mg/m2 daily for 5 days, repeated for 2 weeks) and 50 patients received window therapy with vincristine 1.5 mg/m2 (weeks 0, 1, 3, and 4) and two cycles of irinotecan (20 mg/m2 daily for 5 days, repeated for 2 weeks). Patients who achieved a partial response (PR) or complete response (CR) received these agents alternating with vincristine (V; 1.5/mg/m2), dactinomycin (A; 1.5 mg/m2), and cyclophosphamide (C; 2.2 g/m2) during weeks 6 through 41. Nonresponders were treated with VAC alone. Radiotherapy was administered to sites of disease at weeks 15 to 21.


RESULTS
The window response rate (PR/CR) for patients who received irinotecan was 42% (95% CI, 38% to 80%) but the high progressive disease (PD) rate of 32% (95% CI, 11% to 52%) prompted closure of the trial. The window CR/PR rate for patients who received vincristine and irinotecan was 70% (95% CI, 57% to 83%), and the PD rate was only 8%. GI toxicities (abdominal pain, diarrhea, dehydration) were the most common adverse effects associated with the administration of irinotecan.


CONCLUSIONS
The combination of vincristine and irinotecan is highly active in metastatic rhabdomyosarcoma. The different mechanism of action and nonoverlapping toxicity profile with VAC makes this combination an attractive candidate for further testing in intermediate risk patients with rhabdomyosarcoma.
Pappo
Alberto S
AS
Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA. aspappo@txccc.org
Lyden
Elizabeth
E
Breitfeld
Phillip
P
Donaldson
Sarah S
SS
Wiener
Eugene
E
Parham
David
D
Crews
Kristine R
KR
Houghton
Peter
P
Meyer
William H
WH
D000293:Adolescent; D000328:Adult; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002166:Camptothecin / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000008:administration & dosage; D003609:Dactinomycin / Q000008:administration & dosage; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007223:Infant; D000077146:Irinotecan; D008297:Male; D009362:Neoplasm Metastasis; D012208:Rhabdomyosarcoma / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy; D016896:Treatment Outcome; D014750:Vincristine / Q000008:administration & dosage
D000972:Antineoplastic Agents, Phytogenic; D003609:Dactinomycin; D014750:Vincristine; D000077146:Irinotecan; D003520:Cyclophosphamide; D002166:Camptothecin