Immune changes in patients with colorectal cancer treated by adjuvant therapy with monoclonal antibody 17-1A: a pilot study

Immune responses in advanced colorectal cancer following repeated intradermal vaccination with the anti-CEA murine monoclonal antibody, PR1A3: results of a phase I study

BACKGROUND AND AIMS

The aim was to determine the toxicity, clinical and immune responses to the murine monoclonal anti-carcinoembryonic antigen (CEA) antibody, PR1A3, in patients with advanced colorectal cancer.

MATERIALS AND METHODS

Fifteen patients with advanced colorectal cancer received either 0.5-, 1.0- or 5.0-mg doses of PR1A3 mixed with 10% w/v Alum adjuvant (Superfos Biosector, Denmark) intradermally at 4-week intervals for 3 months. Patient serum was assessed for anti-idiotypic (Ab2), anti-anti-idiotypic (Ab3) and human anti-mouse antibody (HAMA) reactivity. Peripheral blood mononuclear cell (PBMC) proliferation with phytohaemagglutinin (PHA), CEA and PR1A3, stimulated IL-2, IL-4 and IFN-gamma levels and PR1A3-stimulated IL-2 receptor expression during immunotherapy were determined. Comparisons were made with 16 age-matched controls without malignant disease.

RESULTS

Hyperimmune sera from 12 of the 15 patients showed Ab2 reactivity with no detectable Ab3 responses. Strong HAMA reactivity was recorded in 7 of the 15 cases with no adverse clinical effect. Delayed-type hypersensitivity (DTH) responses developed in 12 of the 15 patients. Pre-treatment PBMC proliferation with PHA was subnormal in each patient compared with controls, becoming normal (or supranormal) in all patients during immunisation (P<0.001). PBMC proliferation with CEA and PR1A3 increased during immunotherapy (P<0.001) along with stimulated production of IL-2, IFN-gamma and IL-2 receptor expression. Progressive disease was observed in 14 of the 15 patients with minimal toxicity.

CONCLUSION

PR1A3 generated limited idiotypic responses but robust DTH reactivity in most patients. In vitro PBMC proliferation with mitogens and recall antigens is greatly increased during the course of immunisation, with a shift in stimulated cytokine profile.

The Effect of Edrecolomab (Mo17-1A) or Fluorouracil-Based Chemotherapy on Specific Immune Parameters in Patients with Colorectal Cancer

OBJECTIVES

We investigated the immune profile of patients with resected Dukes' stage C colorectal cancer (CRC), receiving adjuvant therapy with edrecolomab (Mo17-1A) or first-line 5-fluorouracil (5-FU)-based chemotherapy.

PATIENTS AND METHODS

Patients received either 5 doses of Mo17-1A over 13 weeks, or 5-FU/leucovorin, or 5-FU/levamisole over 6 and 12 months, respectively. Peripheral blood was collected postoperatively and 4 months after therapy initiation. Peripheral blood mononuclear cells were tested in the autologous mixed lymphocyte reaction (AMLR), for natural killer (NK) and lymphokine-activated killer (LAK) cell activity. Serum cytokines were quantified by ELISA.

RESULTS

Fifty-two patients entered the study. Postoperatively, they exhibited decreased levels of interleukin (IL)-2, interferon-gamma, IL-12, granulocyte-macrophage colony-stimulating factor and IL-15, low cellular immune responses (AMLR, NK- and LAK-cytotoxicity) and increased levels of IL-1beta, tumor necrosis factor-alpha, IL-6, IL-10 and prostaglandin E(2). After four months of therapy, patients receiving edrecolomab demonstrated enhanced AMLR, NK, LAK activity, increased serum levels of cytokines regulating such responses and reduced levels of acute-phase cytokines and immune suppressors, compared to patients treated with conventional chemotherapy.

CONCLUSIONS

Postoperative adjuvant therapy with edrecolomab restores the in vivo deficient immune responses of patients with resected Dukes' C CRC despite its clinical ineffectiveness in recent randomized adjuvant trials. These results suggest that further immunological studies with the combination of edrecolomab and chemotherapy are required.