9668 Background: Human Fibroblast Activation Protein (FAP)/seprase is a 97-kd surface glycoprotein with dipeptidyl peptidase and gelatinolytic activity expressed on tumor associated fibroblasts in the majority of epithelial cancers including colon adenocarcinomas. FAP overexpression has been shown to promote tumor growth in animal models, and clinical trials targeting FAP enzymatic activity have been initiated. The primary objective of this study was to evaluate expression levels of FAP in human colon cancers by immunohistochemisty and relate its expression to clinical outcome. Methods: Sections of paraffin-embedded resected primary human colon cancer specimens from 1996 through 2001 within the Fox Chase Cancer Center tumor bank were stained with D8 antibody directed against FAP/seprase. Grading of staining was performed by assessment of FAP staining intensity (none, light, medium, dark) and overall percent of stromal staining (0, 1–10%, 11–50%, 51%+) as previously established. Survival time and time to recurrence data were analyzed using Kaplan-Meier plots, log-rank tests and Cox proportional hazards models. Results: 138 patients with resected specimens were available for study (mean follow-up 1050 days) with 6 patients (4%) stage I, 52 (38%) stage II, 43 (31%) stage III, and 37 (27%) stage IV. FAP was detected in over 93% of specimens and semiquantitative staining was scored as 1+ in 28 (20%), 2+ in 52 (38%) and 3+ in 49 (35%). FAP staining was graded as light in 45 (33%), medium in 48 (35%), and dark in 36 (26%). Overall survival was higher in patients with medium or dark staining intensity (median days not yet achieved) versus those with no or light staining intensity (median = 1415 days, p= .02). However, the impact of FAP intensity on overall survival was lost when analyzed with stage within a multivariate model. Thus, FAP staining intensity correlated inversely with stage. Conclusion: Patients whose colon cancers intensely express FAP are more likely to have early stage disease. This suggests that clinical trials utilizing FAP as a therapeutic target to disrupt FAP-driven tumor growth may have greater potential efficacy prior to the establishment of metastatic disease. No significant financial relationships to disclose.

During clonal expansion of antigen (Ag)-stimulated B lymphocytes, the immunoglobulin (Ig) variable region (V) genes undergo point mutation at a high rate (McKean et al. 1984; Clarke et al. 1985). Somatic diversity results from the sequential accumulation of such mutations (Clarke et al. 1985; McKean et al. 1984; Cumano and Rajewsky 1986; Jacob et al. 1991b). These mutations, and selection of them by Ag, have important consequences for the kinetics, quality, and size of the resulting immune response. Hence, somatic mutation is a dynamic system and in this sense is distinct from mechanisms that shape the preimmune repertoire such as combinatorial joining and gene conversion.

The effect of the chemopreventive agent D,L-alpha-difluoromethylornithine (DFMO) on the incidence of skin squamous cell carcinoma was studied in SENCAR mice treated weekly with topical applications of benzo(a)pyrene (B(a)P) (0.15 mmol, 2 x /week) on the dorsal skin. Animals were randomized to receive either chow or chow supplemented with DFMO (1 g/1 kg) and studied at 10, 15, 20, 25, and 30 weeks of B(a)P treatment. Morphometric analyses at each timepoint evaluated the epidermal thickness (ET) and the number of epidermal nucleated layers (NL). The ET increased from 12-17 microns as early as 10 weeks after B(a)P treatment, reaching 22 microns at 20 weeks, and 27 microns at 25 weeks (130% increase). The NL also increased markedly. A relatively modest increase in ET was observed in animals treated with B(a)P and DFMO (16% at 15 weeks, 53% at 20 weeks, and 85% at 25 weeks) as compared to controls. The relative increase in NL showed a similar pattern. Although extensive epidermal hyperplasia was seen early, clear-cut focal premalignant lesions were not identifiable before week 20 of B(a)P treatment. At 20 weeks, the most frequently noted focal premalignant lesions in carcinogen-treated animals (without DFMO) were moderate dysplasias. At 25 and 30 weeks, a large increase was seen in the incidence of more advanced dysplastic lesions and invasive carcinomas. In the group treated with B(a)P and DFMO, a marked reduction in the number of carcinomas was observed at 25 and 30 weeks. At 25 weeks, DFMO reduced tumor yield from 5.8 to 3.2 carcinomas per mouse. At 30 weeks, the reduction was from 13.1 to 5.7 carcinomas per mouse (57% reduction). Collectively, these data emphasize the strong chemopreventive effect of DFMO against tumors in the mouse skin complete carcinogenesis model, as indicated by the reduction of overall skin tumor incidence and the decreased epidermal hyperplasia in DFMO-treated animals. Morphometrically defined increases in ET and NL can be used as early biomarkers of DFMO chemoprevention in mouse skin tumorigenesis.

In 1970, before any antigen-bound immunoglobulin structure had been solved, Elvin Kabat proposed that regions of high amino acid diversity would be the antigen binding sites of immunoglobulin (Kabat, 1970). Conversely, sites of low variability were proposed to be structural, framework regions. This variability was defined by Wu and Kabat as the number of different amino acids found at a site divided by the relative frequency of the most common amino acid at that site (Wu and Kabat, 1970). Several groups have subsequently devised improvements of Kabat-Wu variability analysis (Litwin and Jores, 1992). While these methods are somewhat better than Kabat Wu, they still suffer from Kabat-Wu's basic limitation: they account for only the most common one or two amino acids in estimating diversity. This leads to underestimates of low diversities and exaggerations of high diversities. Shannon information analysis eliminates serious bias and is more stable than Kabat-Wu and second generation measures of diversity (Jores et al. 1990; Wu and Kabat 1970). Statistical reliability can be measured using Shannon analysis, and Shannon measurements can be provided with error estimates. Here we use Shannon's method to analyze the amino acid diversity at each site of T cell receptor Vα and Vβ to identify complementarity determining regions and framework sites. Our results reveal that the T cell receptor is significantly more diverse than immunoglobulin-suggesting T cell receptor has more than the previously-discovered four complementarity determining regions. These new complementarity determining regions may represent a larger antigen combining site, additional combining sites, or an evolutionary strategy to avoid inappropriate interaction with other molecules

In order to determine whether preresectional chemoradiotherapy (CTRT) would influence resectability, local control, and survival of patients with localized pancreatic adenocarcinoma, a 5 1/2-year prospective study of 39 patients treated with preoperative radiation therapy, 5-Fluorouracil (5-FU), and Mitomycin C has been performed. Thirty patients had celiotomy after CTRT (1/39 died while receiving CTRT, one refused surgery, and seven had extrapancreatic disease progression). Seventeen (57%) had resections (seven total, two distal subtotal, and eight Whipple pancreaticoduodenectomies). All had clear margins of excision, and only one had any positive lymph nodes in the resected specimen. Eleven patients with resection had Stage I cancers (5 T1b, 6 T2), five had Stage II, and one had a Stage III lesion. Previous bypass surgery, age, clinical response to CTRT, and tumor size had no influence on resectability. Two patients died postoperatively (12%) early in the series. Three others suffered major morbidity (chylous ascites requiring peritoneovenous shunt, ARDS, and prolonged afferent loop obstruction leading to a fatal liver abscess 5 months after surgery). Two patients with resection are alive without recurrence at 48 months after tissue diagnosis, and six others are also alive without recurrence, after from 6 to 23 months. In summary, resectability is probably enhanced and nodal metastases and resection margins are downstaged by preoperative CTRT. Demonstration of an improved survival benefit awaits further observation and phase III trials.

Epithelial cells obtained from autopsies of full-term fetuses or infants less than 1 year old were isolated, amplified in primary cultures and inoculated in deepithelialized rat tracheas. These tracheas were then sealed and transplanted subcutaneously into irradiated athymic nude mice. Four weeks after transplantation the tracheal lumen was completely covered by epithelium, most of which was of mucociliary respiratory type. At this stage, tracheal transplants containing tracheobronchial epithelium from 20 different donors were exposed to silastic devices containing 0, 0.5, 1 and 2 mg paraformaldehyde. The tracheal transplants were examined histologically at 2, 4, 8, and 16 weeks after transplantation. Before sacrifice, all animals were injected with a single pulse of tritiated thymidine. Important epithelial alterations could be seen in the formaldehyde treated transplants with a maximum effect visible at 2 weeks after exposure. The highest dose of 2 mg produced, in most cases, numerous areas of epithelial erosion and inflammation whereas this effect was not as evident with the lower doses. All doses produced areas of hyperplastic epithelium alternating with areas of pleomorphic-atrophic epithelium. Although the differences in predominance of different types of epithelium was not clearly dose-dependent, the labeling index (LI) showed dose dependence between 2 and 4 weeks after initiation of exposure. The maximum mean LI was three to four times higher than normal, although in some focal hyperplastic-metaplastic lesions the LI was increased up to 20 times. These studies show that formaldehyde, although toxic at higher doses, is able to elicit at lower doses a proliferative response of the human respiratory epithelium that is not preceded by a massive toxic effect. This response is similar, although less intense than that of the rat respiratory epithelium in which formaldehyde proved to be a carcinogen.