Decrease of a normal colon and granulocyte antigen (NCA) in whole lysed blood of myelosuppressed patients

Preclinical evaluation of carcinoembryonic cell adhesion molecule (CEACAM) 6 as potential therapy target for pancreatic adenocarcinoma

Despite the availability of new targeted therapies, ductal pancreatic adenocarcinoma continues to carry a poor prognosis. Carcinoembryonic antigen-related cell adhesion molecule (CEACAM)6 has been reported as a potential biomarker and therapy target for this malignancy. We have evaluated CEACAM6 as a potential therapy target, using an antibody-drug conjugate (ADC). Expression of CEACAM6 in pancreatic adenocarcinomas was determined using immunohistochemistry on tissue microarrays. The expression pattern in granulocytes and granulocytic precursors was measured by flow cytometry. Murine xenograft and non-human primate models served to evaluate efficacy and safety, respectively. Robust expression of CEACAM6 was found in > 90% of invasive pancreatic adenocarcinomas as well as in intraepithelial neoplastic lesions. In the granulocytic lineage, CEACAM6 was expressed at all stages of granulocytic maturation except for the early lineage-committed precursor cell. The anti-CEACAM6 ADC showed efficacy against established CEACAM6-expressing tumours. In non-human primates, antigen-dependent toxicity of the ADC consisted of dose-dependent and reversible depletion of granulocytes and their precursors. This was associated with preferential and rapid localization of the antibody in bone marrow, as determined by sequential in vivo PET imaging of the radiolabelled anti-CEACAM6. Localization of the radiolabelled tracer could be attenuated by predosing with unlabelled antibody confirming specific accumulation in this compartment. Based on the expression pattern in normal and malignant pancreatic tissues, efficacy against established tumours and limited and reversible bone marrow toxicity, we propose that CEACAM6 should be considered for an ADC-based therapy approach against pancreatic adenocarcinomas and possibly other CEACAM6-positive neoplasms.

Serum NCA in bone marrow transplant recipients and its metabolism

Normal colon and granulocyte antigen (NCA) in serum from 24 patients undergoing bone marrow transplantation (BMT), mostly for leukemic disease, was studied for a period of 0-60 days before/after transplantation. Out of the 23 patients with a take, 20 acquired elevated serum NCA. One patient had a rejection of the transplantation and never showed a rise of NCA values. Thirteen patients were studied in detail; 7 of them had an NCA rise 1-4 days before take, 4 at the day of take and 2 patients 1-4 days later. To investigate the rate of NCA turnover, 125I-NCA was injected into Macaca irus monkeys. One hour after injection, 87% of the injected substance had left the circulation. The prime site of accumulation was the liver. Thereafter, blood NCA decreased at a slower and linear rate. Of the substance seen at the beginning of the second phase 50% had been eliminated after 30 hours. The data support the theory that NCA is produced by the myeloid cells in bone marrow, that it has a rapid metabolism and therefore is of interest as a marker of bone marrow activity in health and malignant disease.

NCA: a differentiation antigen of myelopoietic cells in humans and hominoid monkeys

NCA, a normal colonic and granulocytic antigen, could be demonstrated in serum and in myelopoietic, but not lymphopoietic or erythropoietic, cells of Homo sapiens and other Primates. The levels of NCA in both serum and myelopoietic cells of Homo and hominoids were higher than those of more distant relatives of the same order. Thus, the classic phylogenetic differences are reflected also by the distribution of NCA. Hyperimmunization of Macaca irus, in which the NCA content of serum and cells is low, led to occurrence of anti-NCA IgG in all animals. The phylogenetic differences may accordingly have to do with slight antigenic NCA differences between Homo and other Primates rather than differences in amount only. Purified NCA did not affect growth and maturation of myelopoietic stem cells in vitro, whereas anti-NCA inhibited development of the majority of myelopoietic clusters and colonies.