Clonal expansion and loss of heterozygosity at chromosomes 9p and 17p in premalignant esophageal (Barrett's) tissue.

BACKGROUND: Abnormalities involving the p16 (also known as cyclin-dependent kinase N2 [CDKN2], p16 [INK4a], or MTS1) and p53 (also known as TP53) tumor suppressor genes are highly prevalent in esophageal adenocarcinomas. Loss of heterozygosity (LOH) at 9p21 and 17p13 chromosomes (locations for p16 and p53 genes, respectively) is frequently observed in the premalignant condition, Barrett's esophagus. We studied extensively the distribution and heterogeneity of LOH at 9p and 17p chromosomes throughout the Barrett's segment in patients who have not yet developed esophageal adenocarcinoma. METHODS: We evaluated 404 samples from 61 consecutive patients enrolled in the Seattle Barrett's Esophagus Study from February 1995 through September 1998. All patients had high-grade dysplasia but no diagnosis of cancer. The samples were assayed for LOH at 9p and 17p chromosomes after amplification of genomic DNA by use of polymerase chain reaction and DNA genotyping. The cell fractions were purified by flow cytometry on the basis of DNA content and proliferation-associated antigen labeling. Association between LOH at 9p and LOH at 17p with flow cytometric abnormalities was determined by chi-squared test, and logistic regression models were used to model and test for the extent to which a particular genotype was found in 2-cm intervals. RESULTS AND CONCLUSIONS: LOH at 9p and 17p chromosomes are highly prevalent somatic genetic lesions in premalignant Barrett's tissue. LOH at 9p is more common than LOH at 17p in diploid samples and can be detected over greater regions of Barrett's epithelium. In most patients with high-grade dysplasia, the Barrett's mucosa contains a mosaic of clones and subclones with different patterns of LOH. Some clones had expanded to involve extensive regions of Barrett's epithelium. LOH at 9p and 17p chromosomes may be useful biomarkers to stratify patients' risk of progression to esophageal cancer.

Population study of allelic diversity in the human MHC class I-related MIC-A gene.

The polymorphism of major histocompatibility complex (MHC) class I HLA-A, -B, and -C molecules may have evolved through pathogen-driven selection of alleles with diverse peptide-binding specificities. Two MHC-encoded molecules that are distantly related to class I, MIC-A and MIC-B, do not function in the presentation of pathogen-derived peptides to T cells with alphabeta T-cell receptors (TCRs), but are broadly recognized by intraepithelial T cells with gammadelta TCRs. However, both MIC-A and MIC-B are polymorphic, displaying an unusual distribution of a number of variant amino acids in their extracellular alpha1, alpha2, and alpha3 domains. In order to further define the polymorphism of MIC-A, we examined its alleles among 275 individuals with common and rare HLA genotypes. Of 16 previously defined alleles, 12 were confirmed and 5 new alleles were identified. A two-by-two analysis of MIC-A and HLA-B alleles uncovered a number of statistically significant associations. These results confirm and extend previous knowledge on the polymorphism of MIC-A. The strong positive linkage of certain MIC-A and HLA-B alleles may have implications for studies related to MHC-associated diseases and transplantation.

Association of HLA-C disparity with graft failure after marrow transplantation from unrelated donors.

Disparity for HLA-A or HLA-B antigens increases the risk of marrow graft rejection, but the relevance of HLA-C is unknown because typing methods have not been sufficiently accurate for clinical use. We designed a matched case-control study and employed DNA sequencing methods to evaluate the role of HLA-C disparity in 21 patients who experienced graft failure (cases) following transplantation with unmanipulated marrow from either HLA-A, B serologically matched, DRB1 matched (n = 14) or single locus mismatched (n = 7) unrelated donors. For each case, two patients who successfully engrafted were selected as controls based on similarity for factors known or suspected to influence engraftment. The estimated odds ratio (OR) of graft failure for an HLA-C mismatch relative to match (univariable model) was 5.2 (95% CI, 1.4, 19; P = .01). Serologically undetectable HLA-A or HLA-B allele disparity was also associated with graft failure. The association between HLA-C disparity and graft failure remained significant even after accounting for the contribution of HLA-A and/or HLA-B allele disparity (OR 4.0; 95% CI, 1.1, 15; likelihood ratio test P = .03). These results show that HLA-C functions as a transplantation antigen and that HLA-A and HLA-B allele mismatches are biologically important. Molecular-based methods for pretransplant assessment of class I compatibility should be implemented for the selection of unrelated marrow donors.

Definition of HLA-DQ as a transplantation antigen.

Recent studies have demonstrated the importance of recipient HLA-DRB1 allele disparity in the development of acute graft-versus-host disease (GVHD) after unrelated donor marrow transplantation. The role of HLA-DQB1 allele disparity in this clinical setting is unknown. To elucidate the biological importance of HLA-DQB1, we conducted a retrospective analysis of 449 HLA-A, -B, and -DR serologically matched unrelated donor transplants. Molecular typing of HLA-DRB1 and HLA-DQB1 alleles revealed 335 DRB1 and DQB1 matched pairs; 41 DRB1 matched and DQB1 mismatched pairs; 48 DRB1 mismatched and DQB1 matched pairs; and 25 DRB1 and DQB1 mismatched pairs. The conditional probabilities of grades III-IV acute GVHD were 0.42, 0.61, 0.55, and 0.71, respectively. The relative risk of acute GVHD associated with a single locus HLA-DQB1 mismatch was 1.8 (1.1, 2.7; P = 0.01), and the risk associated with any HLA-DQB1 and/or HLA-DRB1 mismatch was 1.6 (1.2, 2.2; P = 0.003). These results provide evidence that HLA-DQ is a transplant antigen and suggest that evaluation of both HLA-DQB1 and HLA-DRB1 is necessary in selecting potential donors.

False positive tumor markers: elevation in patients with breast cancer on FAC-type chemotherapy and correlation with the development of hand-foot syndrome.

Breast cancer patients on dose-intensive chemotherapy often have elevated tumor markers during the course of treatment. Our objective was to estimate the incidence of a "false positive" tumor marker screen and to determine whether hand-foot epithelial damage was correlated. Data from 53 patients with high risk primary breast cancer who had undergone adjuvant or neoadjuvant 5FU-containing chemotherapy (FAC or FAC plus G-CSF) for 3 to 12 months were reviewed. The relationship between tumor marker elevation and disease recurrence, regimen intensity, and the occurrence of hand-foot syndrome was examined. Thirty-three of the 53 patients had elevated tumor markers in the absence of recurrent disease. The false positive rate was higher in patients who underwent FAC plus G-CSF chemotherapy than in patients who underwent FAC chemotherapy (92% vs 55%, p = .01). A false positive marker screen was associated with the occurrence of hand-foot syndrome even when the effect of regimen was accounted for by stratification (p = .01). Tumor marker screening of breast cancer patients on this type of adjuvant chemotherapy has poor specificity for recurrent malignancy. These data suggest tumor marker elevation may be an indicator of epithelial toxicity during chemotherapy, manifested clinically as hand-foot syndrome.

The significance of HLA-DRB1 matching on clinical outcome after HLA-A, B, DR identical unrelated donor marrow transplantation.

Despite matching for serologically defined HLA-A, B, DR antigens, acute graft-versus-host disease (GVHD) is a major complication contributing to increased morbidity and mortality in patients who undergo marrow transplantation from unrelated donors. The extent to which unrecognized mismatching for alleles that encode DR1-DR18 contribute to the increased risk of acute GVHD and overall survival is unknown. We analyzed 364 patients and their HLA-A, B, DR serologically matched donors to determine whether molecular typing of DRB1 alleles can allow more accurate donor/recipient matching and thereby improve clinical outcome after marrow transplantation. DRB1 alleles were typed by sequence-specific oligonucleotide probe hybridization methods. Selected alleles were confirmed by DNA sequencing. Of the 364 pairs, 305 were matched and 59 were mismatched for DRB1. The probability of moderate to severe acute GVHD was .48 for the matched and .70 for the mismatched patients. Compared with mismatched patients, the estimated relative risk (RR) of GVHD for matched patients was .58 (95% confidence interval [CI], .40 to .85). DRB1 matching decreased the risk of transplant-related mortality (RR, .66; 95% CI, .44 to .97) and was associated with decreased overall mortality (RR, .71; 95% CI, .51 to 1.0). Therefore, matching DRB1 alleles of the donor and recipient decreases the risk of acute GVHD and improves survival after unrelated marrow transplantation. These results indicate that prospective matching of patients and donors for DRB1 alleles is warranted.

The role of HLA-DPB1 disparity in the development of acute graft-versus-host disease following unrelated donor marrow transplantation.

The role of HLA-DPB1 disparity in the development of acute graft-versus-host disease (GVHD) following unrelated donor (URD) marrow transplantation is unknown. We studied 129 patients who underwent marrow transplantation from HLA-A, -B, -DRB, and -DQB matched URDs to determine whether matching for HLA-DPB1 alleles significantly decreased the risk of developing acute GVHD. HLA-DPB1 alleles were determined by sequence-specific oligonucleotide hybridization and by the number of patient DPB1 alleles not shared by the donor scored. The Kaplan-Meier probability of developing grades II to IV acute GVHD was determined for patients incompatible for zero (group A), one (group B), or two (group C) DPB1 alleles. Of the 129 pairs, there was no recipient DPB1 incompatibility in 28 (22%), one DPB1 mismatch in 72 (56%), and two DPB1 mismatches in 29 (22%). The probability of grades II to IV acute GVHD was 0.69 (0.50, 0.86) for group A, 0.83 (0.73, 0.91) for group B, and 0.72 (0.56, 0.87) for group C (P = .63). These results indicate that matching patients and unrelated donors for HLA-A, -B, -DRB, and -DQB does not predict for matching at DPB1. However, recipient incompatibility for DPB1 alleles does not detectably influence the risk of acute GVHD. Therefore, HLA-DP disparity should not be used as an exclusion criterion for donor selection in unrelated marrow transplantation.

Marrow transplantation from unrelated donors for treatment of hematologic malignancies: effect of mismatching for one HLA locus.

One hundred twelve patients less than 36 years old received marrow grafts from unrelated donors as treatment for hematologic malignancy. Seventy donor/recipient pairs were phenotypically identical for HLA-A, -B, and -D, while 42 had a "minor" disparity at one HLA locus. There was an increase in the risk of acute graft-versus-host disease (GVHD) in patients receiving HLA-partially matched grafts compared with those receiving HLA-matched grafts (51% v 36% probability of grades III-IV acute GVHD). However, in this cohort of patients, there was no significant difference in survival (at 1.5 years, 46% v 51% for good-risk patients, 44% v 30% for poor-risk patients). This finding suggests that some degree of HLA disparity can be tolerated in young patients transplanted from unrelated donors for malignant disease, thus making transplantation an option available to larger numbers of patients.

Marrow transplantation from HLA-matched unrelated donors for treatment of hematologic malignancies.

Less than 40% of the patients who could benefit from marrow transplantation have an HLA-matched relative who can serve as a donor. For this reason, several centers have explored marrow transplantation from other categories of donors. This retrospective study analyzes the results of marrow transplantation for 52 patients receiving grafts from HLA-A,B,DR,Dw-phenotypically matched, MLC-compatible, unrelated volunteer donors compared to a disease, disease-stage, and age-matched cohort of 104 patients transplanted from HLA-genotypically identical sibling donors. The patients transplanted from unrelated donors had an increased incidence of grade II-IV acute graft-versus-host disease compared to patients transplanted from related donors (79% vs. 36%, P much less than 0.001). However, the probability of relapse-free survival appears similar in the two groups (P = 0.39 over all, with estimates of 41% vs. 46% at 1 year). We conclude from this preliminary data that marrow transplantation from HLA-matched unrelated donors should be considered in most, if not all, circumstances where transplantation from an HLA-matched sibling would be indicated if such a donor were available.