Jayant Shetye

Immunohistochemical monitoring of metastatic colorectal carcinoma in patients treated with monoclonal antibodies (MAb 17-1A)*

SummaryA therapeutic trial using repeated doses of a mouse monoclonal antibody against the tumor-associated antigen (TAA) CO17-1A in metastatic colorectal carcinomas was carried out. Metastatic lesions sampled by repeated thick needle (1.2 mm) biopsies during therapy were examined immunohistochemically for the presence of various TAAs, mouse IgG, complement, and infiltrating leukocytes. The CO17-1A was consistently expressed in all cases along the basement membrane of tumor glands and could only be demonstrated on cryostat sections whereas the TAAs GICA19-9, GA73-3, and Br55-2 were also visualized in B5-fixed paraffin-embedded biopsies. The CO17-1A and GA73-3 were predominantly present at the basal region in contrast to the GICA 19-9 and Br55-2 which were predominant at the luminal and the apical region of the tumor glands. Antigenic modulation was not seen either after 24–72 h or during prolonged treatment. In all cases the infused mouse IgG was detected, from 24 h after infusion up to 6–8 weeks, mainly along the basal region of tumor glands. In 13/14 posttreatment biopsies, complement factor C3 was found at the same sites as mouse IgG. In 6 out of 9 posttreatment biopsies an increase in mononuclear cells (monocytes, natural killer (NK) cells and/or T cells) was observed. Monocytes were close to the tumor cells whereas NK cells and T cells were predominantly scattered in the stroma.

Augmentation of the immune response with granulocyte-macrophage colony-stimulating factor and other hematopoietic growth factors.

Granulocyte-macrophage colony-stimulating factor is by far the most widely used hematopoietic growth factor to augment immune responses. At present, the best secured effect is as an adjuvant cytokine for vaccination. Granulocyte-macrophage colony-stimulating factor can be delivered as gene-transduced tumor cells, as plasmid DNA, or as the soluble free granulocyte-macrophage colony-stimulating factor protein. Granulocyte-macrophage colony-stimulating factor must be present at the same site as the vaccine component. Granulocyte-macrophage colony-stimulating factor may also augment the effect of therapeutic monoclonal antibodies by enhancing various effector functions such as antibody-dependent cellular cytotoxicity and amplifying an idiotypic network response (i.e., antitumor immunity). It may also be advantageous to combine granulocyte colony-stimulating factor with monoclonal antibodies (neutrophil and monocyte antibody-dependent cellular cytotoxicity) for tumor therapy. However, these growth factors might also induce immune suppression, which may hamper the contemplated effect of the growth factor. It is urgently warranted to better understand these dual effects on the immune system so that we can find optimal uses for the growth factors in various clinical settings.

Flat adenoma-adenocarcinoma sequence in the colon of rats

PURPOSE: As there is an increased awareness of the existence of a “flat adenoma-adenocarcinoma sequence” in the colonic mucosa of human subjects, the aims of the study were to assess whether flat colonic adenocarcinomas in rats are also preceded by flat adenomas, as is reported in humans, and to determine the frequency of flat lesions compared with exophytic lesions in the colon of rats. METHOD: The colonotropic carcinogen 1,2-dimethylhydrazine was injected subcutaneously in 300 Sprague-Dawley rats for 27 weeks. RESULTS: A total of 358 tumors developed in 278 of the 300 rats. Of the 60 adenomas found at histology, 25 percent were flat adenomas. Of the 298 adenocarcinomas, 12.7 percent had originated in a fiat adenoma. Of the 180 colonic neoplasias (adenomas or adenocarcinomas), 29.4 percent were flat neoplasias (flat adenomas or adenocarcinomas arising in a flat adenoma), and the remaining 70.6 percent were exophytic neoplasias (tubulo or villous adenomas or adenocarcinomas arising in exophytic adenomas). From the 298 colonic adenocarcinomas, 1 was a intramucosal adenocarcinoma, 87 were overt adenocarcinomas, and 90 were lymphoid-associated carcinomas; in those 298 adenocarcinomas, no preneoplastic lesion could be recorded. In 208 animals, biopsies were taken from macroscopically visible colonic lesions, and, in the remaining 70 animals, the entire colon was processed for histologic examination. Flat adenomas were found in 3.8 percent of the 208 biopsy specimens and in 10 percent of the 70 colectomy specimens. Further, of the 40 adenomas found in biopsy specimens, 20 percent were flat adenomas, and, of the 20 adenomas found in colectomy specimens, 35 percent were flat adenomas. CONCLUSIONS: The study reported herein indicates the existence of a “flat adenomaadenocarcinoma sequence” in the colonic mucosa of Sprague-Dawley rats. The flat lesions of the colon constituted approximately one-third of the total neoplastic lesions seen in the rat following injections of 1,2-dimethylhydrazine. More flat adenomas were detected at histologic examination of the entire colon than in biopsies obtained from the macroscopically visible colonic lesions. Consequently, flat adenomas may be overlooked by naked-eye examination.

Circumferential resection margin as a prognostic marker in the modern multidisciplinary management of rectal cancer.

BACKGROUND: A positive circumferential resection margin has been associated with a high risk of local recurrence and a decrease in survival in patients who have rectal cancer. OBJECTIVE: The purpose of this study was to analyze the involvement of circumferential resection margin in local recurrence and survival in a multidisciplinary population-based setting by using tailored oncological therapy and surgery with total mesorectal excision. DESIGN: Data were collected in a prospective database and retrospectively analyzed. Between 1996 and 2009, 448 patients with rectal cancer underwent a curative bowel resection. SETTINGS: Population-based data were collected at a single institution in the county of Västmanland, Sweden. RESULTS: Preoperative radiotherapy was delivered to 334 patients (74%); it was delivered to 35 patients (8%) concomitantly with preoperative chemotherapy. In 70 patients (16%), en bloc resections of the prostate and vagina were performed. Intraoperative perforations were seen in 7 patients (1.6%). The mesorectal fascia was assessed as complete in 117/118 cases. In 32 cases (7%), the circumferential resection margin was 1 mm or less. After a median follow-up of 68 months, 5 (1.1%) patients developed a local recurrence; one of them had circumferential resection margin involvement. The 5-year overall survival was 77%. In the multivariate analysis, the circumferential resection margin was not an independent factor for disease-free survival. LIMITATIONS: Mesorectal fascia was not assessed before 2007. The findings might be explained by a type II error but, from a clinical perspective, enough patients were included to motivate the conclusion of the study. CONCLUSIONS: Circumferential resection margin is an important measurement in rectal cancer pathology, but the correlation to local recurrence is much less than previously stated, probably because of oncological treatment and surgery that respects the mesorectal fascia and, when required, en bloc resections. Circumferential resection margin should not be used as a prognostic marker in the modern multidisciplinary management of rectal cancer.

Normal colon of Sprague-Dawley rats

SummaryThe patterns of expression of the human-tumor-associated antigens, CO17-1A, GA73-3, BR55-2, GICA19-9, CA50 and carcino-embryonic antigen (CEA) were studied in the normal colonic mucosa (the last three also in the serum) of Sprague-Dawley rats. Four immunohistochemically different segments were identified: caecum, ascending colon, transverse colon and descending colon. The immunohistochemical reactions of the cells at the lower part of the crypt were essential for the distinction of the four segments. In the caecum, the MAbs 17-1A, 73-3 and 19-9 stained the glycocalyx of the cells of the lower part of the crypts and the Golgi apparatus of the intercalated cells (IC). MAb55-2 stained very weakly the goblet-like cells (GLC) of the lower part of the crypt of transverse colon, in addition to a nearly complete lack of reaction in the upper part of the crypts. In the ascending colon, the lower part of the crypts showed a characteristic diffuse staining of the intercalated cells with MAb55-2. The perinuclear and mucosal staining observed in the GLC of the transverse colon with MAbs 17-1A, 73-3 and 19-9 as against the supranuclear and Golgi zone staining observed in the GLC/goblet cells (GC)/columnar cells (CC) of the lower part of crypts of the descending colon with the same MAbs, distinguished the former segment from the latter. The IC demonstrated by immunohistochemistry in the lower parts of the crypts of caecum and ascending colon appear to correspond to the replicating cells of the colonic crypts.