title: A Phase I trial of 90Y-anti-carcinoembryonic antigen chimeric T84.66 radioimmunotherapy with 5-fluorouracil in patients with metastatic colorectal cancer.
abstract: OBJECTIVE
  Targeted systemic radiation therapy using radiolabeled antibodies results in tumor doses sufficient to produce significant objective responses in the radiosensitive hematological malignancies. Although comparable doses to tumor are achieved with radioimmunotherapy (RIT) in solid tumors, results have been modest primarily because of their relative lack of radiosensitivity. For solid tumors, as with external beam radiotherapy, RIT should have a more important clinical role if combined with other systemic, potentially radiation-enhancing chemotherapy agents and if used as consolidative therapy in the minimal tumor burden setting. The primary objective of this trial was to evaluate the feasibility and toxicities of systemic 90Y-chimeric T84.66 (cT84.66) anti-carcinoembryonic antigen RIT in combination with continuous infusion 5-fluorouracil (5-FU).
  
  
  METHODS
  Patients with chemotherapy-refractory metastatic colorectal cancer were entered. The study was designed for each patient to receive 90Y-cT84.66 anti-carcinoembryonic antigen at 16.6 mCi/m2 as an i.v. bolus infusion combined with 5-FU delivered as a 5-day continuous infusion initiated 4 h before antibody infusion. Cohorts of patients were entered at 5-FU dose levels of 700, 800, 900, and 1000 mg/m2/day. Upon reaching the highest planned dose level of 5-FU, a final cohort received 90Y-cT84.66 at 20.6 mCi/m2 and 5-FU at 1000 mg/m2/day. For all patients, Ca-diethylenetriaminepentaacetic acid at 125 mg/m2 every 12 h was administered for the first 72 h after 90Y-cT84.66. Patients were eligible to receive up to three cycles of 90Y-cT84.66/5-FU every 6 weeks.
  
  
  RESULTS
  Twenty-one patients were treated on this study. All had been heavily pretreated with 19 having previously received 5-FU and 16 having failed two to four chemotherapy regimens. A maximum-tolerated dose of 16.6 mCi/m2 90Y-cT84.66 combined with 1000 mg/m2/day 5-FU was reached. These dose levels are comparable with maximum-tolerated dose levels of each agent alone. Thirteen patients received one cycle and 8 patients two cycles of therapy. Hematopoietic toxicity was dose-limiting and reversible. RIT did not appear to increase nonhematopoietic toxicities associated with 5-FU. Two of 19 patients assayed developed a human anti-chimeric antibody immune response after the first cycle of therapy, which is significantly less than that observed in a previous trial evaluating 90Y-cT84.66 alone. No objective responses were observed. However, 11 patients with progressive disease entering the study demonstrated radiological stable disease of 3-8 months duration and 1 patient demonstrated a mixed response.
  
  
  CONCLUSIONS
  Results from this trial are encouraging and demonstrate the feasibility and possible advantages of combining continuous infusion 5-FU with 90Y-cT84.66 RIT. The addition of 5-FU does not appear to significantly enhance hematological toxicities of the radiolabeled antibody. In addition, 5-FU reduces the development of human anti-chimeric antibody response, permitting multicycle therapy in a larger number of patients. Future efforts should continue to focus on integrating radiation therapy delivered by radiolabeled antibodies into established 5-FU regimens.
authors.affiliation: Division of Radiation Oncology, Beckman Research Institute and City of Hope National Medical Center and Beckman Research Institute, Duarte, California 91010, USA. JWong@coh.org
authors.forename: Jeffrey Y C
authors.initials: JY
authors.lastname: Wong
authors.forename: Stephen
authors.initials: S
authors.lastname: Shibata
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Williams
authors.forename: Cheuk S
authors.initials: CS
authors.lastname: Kwok
authors.forename: An
authors.initials: A
authors.lastname: Liu
authors.forename: David Z
authors.initials: DZ
authors.lastname: Chu
authors.forename: Dave M
authors.initials: DM
authors.lastname: Yamauchi
authors.forename: Sharon
authors.initials: S
authors.lastname: Wilczynski
authors.forename: David N
authors.initials: DN
authors.lastname: Ikle
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wu
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Yazaki
authors.forename: John E
authors.initials: JE
authors.lastname: Shively
authors.forename: James H
authors.initials: JH
authors.lastname: Doroshow
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Raubitschek
mesh_terms: D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000556:secondary / Q000628:therapy*; D003131:Combined Modality Therapy; D005240:Feasibility Studies; D005472:Fluorouracil / Q000627:therapeutic use*; D006801:Humans; D020714:Maximum Tolerated Dose; D016499:Radioimmunotherapy; D011993:Recombinant Fusion Proteins / Q000627:therapeutic use*; D015021:Yttrium Radioisotopes / Q000627:therapeutic use*
chemical_list: D000911:Antibodies, Monoclonal; D000964:Antimetabolites, Antineoplastic; D002272:Carcinoembryonic Antigen; D011993:Recombinant Fusion Proteins; D015021:Yttrium Radioisotopes; D005472:Fluorouracil