Gabriel L. Sica

B7-H3: A costimulatory molecule for T cell activation and IFN-γ production

We describe here a newly identified member of the human B7 family, designated B7 homolog 3 (B7-H3), that shares 20–27% amino acid identity with other B7 family members. B7-H3 mRNA is not detectable in peripheral blood mononuclear cells, although it is found in various normal tissues and in several tumor cell lines. Expression of B7-H3 protein, however, can be induced on dendritic cells (DCs) and monocytes by inflammatory cytokines and a combination of phorbol myristate acetate (PMA) + ionomycin. Soluble B7-H3 protein binds a putative counter-receptor on activated T cells that is distinct from CD28, cytotoxic T lymphocyte antigen 4 (CTLA-4), inducible costimulator (ICOS) and PD-1. B7-H3 costimulates proliferation of both CD4+ and CD8+ T cells, enhances the induction of cytotoxic T cells and selectively stimulates interferon γ (IFN-γ) production in the presence of T cell receptor signaling. In contrast, inclusion of antisense B7-H3 oligonucleotides decreases the expression of B7-H3 on DCs and inhibits IFN-γ production by DC-stimulated allogeneic T cells. Thus, we describe a newly identified costimulatory pathway that may participate in the regulation of cell-mediated immune responses.

B7-H4, a Molecule of the B7 Family, Negatively Regulates T Cell Immunity

We identify a B7 family molecule, B7-H4, by protein sequence analysis and comparative molecular modeling. While B7-H4 mRNA is widely distributed in mouse and human peripheral tissues, cell surface expression of B7-H4 protein is limited and shows an inducible pattern on hematopoietic cells. Putative receptor of B7-H4 can be upregulated on activated T cells. By arresting cell cycle, B7-H4 ligation of T cells has a profound inhibitory effect on the growth, cytokine secretion, and development of cytotoxicity. Administration of B7-H4Ig into mice impairs antigen-specific T cell responses whereas blockade of endogenous B7-H4 by specific monoclonal antibody promotes T cell responses. B7-H4 thus may participate in negative regulation of cell-mediated immunity in peripheral tissues.

Modulation of T-cell-mediated immunity in tumor and graft-versus-host disease models through the LIGHT co-stimulatory pathway.

LIGHT was recently described as a member of the tumor necrosis factor (TNF) ‘superfamily’. We have isolated a mouse homolog of human LIGHT and investigated its immunoregulatory functions in vitro and in vivo. LIGHT has potent, CD28-independent co-stimulatory activity leading to T-cell growth and secretion of gamma interferon and granulocyte–macrophage colony-stimulating factor. Gene transfer of LIGHT induced an antigen-specific cytolytic T-cell response and therapeutic immunity against established mouse P815 tumor. In contrast, blockade of LIGHT by administration of soluble receptor or antibody led to decreased cell-mediated immunity and ameliorated graft-versus-host disease. Our studies identify a previously unknown T-cell co-stimulatory pathway as a potential therapeutic target.

Genomic organization and expression analysis of B7-H4, an immune inhibitory molecule of the B7 family

B7-H4 is a recently identified B7 family member that negatively regulates T cell immunity by the inhibition of T cell proliferation, cytokine production, and cell cycle progression. In this study, we report that the genomic DNA of human B7-H4 is mapped on chromosome 1 comprised of six exons and five introns spanning 66 kb, of which exon 6 is used for alternative splicing to generate two different transcripts. Similar B7-H4 structure is also found in mouse genomic DNA in chromosome 3. A human B7-H4 pseudogene is identified in chromosome 20p11.1 with a single exon and two stop codons in the coding region. Immunohistochemistry analysis using B7-H4-specific mAb demonstrates that B7-H4 is not expressed on the majority of normal human tissues. In contrast, up to 85% (22 of 26) of ovarian cancer and 31% (5 of 16) of lung cancer tissues constitutively express B7-H4. Our results indicate a tight regulation of B7-H4 expression in the translational level in normal peripheral tissues and a potential role of B7-H4 in the evasion of tumor immunity.

CXCL12 and CXCR4 in adenocarcinoma of the lung: Association with metastasis and survival

OBJECTIVES Although the chemokine CXCL12 and its receptor CXCR4 have been implicated in metastasis of non-small cell lung carcinoma, the prognostic significance of these molecules is poorly defined. This study aimed to determine whether expression of these molecules is associated with clinicopathologic features and disease-free survival in non-small cell lung carcinoma. METHODS Immunohistochemical staining for CXCL12 and CXCR4 was performed on 154 primary non-small cell lung carcinomas. Staining intensity was compared with tumor histotype, TNM stage, and disease-free survival; correlation was assessed by using the Fishers exact test, and Kaplan-Meier and Cox multivariate proportional hazards regression analysis. RESULTS Intense CXCL12 immunostaining was associated with nodal metastasis, although no difference in survival was observed. The prognostic relevance of CXCR4 was dependent on its subcellular location: in univariate analysis intense nuclear staining was significantly associated with lower T classification and improved disease-free survival in patients with adenocarcinoma, whereas cytomembranous staining was associated with distant metastasis and decreased disease-free survival. On multivariate analysis, cytomembranous CXCR4 expression conferred a significantly worse disease-free survival (relative risk, 2.8; 95% confidence interval, 1.4-5.7; P = .004). CONCLUSIONS Cytomembranous expression of the chemokine receptor CXCR4 in adenocarcinoma of the lung is an independent risk factor associated with worse disease-free survival, whereas nuclear staining confers a survival benefit. These findings are consistent with a model in which CXCR4 promotes tumor cell proliferation and metastasis when present in the cytoplasm or cell membrane, whereas localization of this molecule in the nucleus prevents it from exerting these effects.

p53 overexpression in morphologically ambiguous endometrial carcinomas correlates with adverse clinical outcomes

The distinction between uterine serous and endometrioid carcinomas can usually be achieved by morphologic examination alone. However, there are occasional ‘morphologically ambiguous endometrial carcinomas’ that show overlapping serous and endometrioid features and defy histologic classification. The primary aim of this study was to assess the clinical significance of p53 overexpression using immunohistochemistry in such tumors. Related aims included (1) assessing interobserver diagnostic concordance for histologic subclassification of these tumors using a panel of pathologists with and without gynecologic pathology expertise and (2) elucidating the histologic features that correlate with p53 status. Thirty-five such cases were identified during the study period. p53 overexpression was seen in 17 of 35 cases. Tumors with p53 overexpression were associated with a significantly inferior progression-free survival and disease-specific survival compared with those that lacked p53 overexpression (3-year progression-free survival and disease-specific survival were 94 and 100% in patients with no p53 overexpression, and 52 and 54% in patients with p53 overexpression; P=0.02 and 0.003, respectively). The consensus diagnosis rendered by gynecologic pathologists was predictive of disease-specific survival (P=0.002), but not progression-free survival (P=0.11). Although the interobserver diagnostic concordance (kappa=0.70) was substantial for gynecologic pathologists, and highly associated with p53 status (77% of ‘favor serous’ cases showed p53 overexpression, whereas only 25% of ‘favor endometrioid’ cases showed p53 overexpression; P=0.005), the concordance between the consensus diagnosis of the two specialized pathologists versus each of three non-specialized pathologists was poor (kappa=0.13–0.25). The histologic feature that correlated most with p53 overexpression was the presence of diffuse high nuclear grade. p53 immunohistochemistry assays in morphologically ambiguous endometrial carcinomas are roughly as clinically informative as gynecologic pathology consultation and can be helpful for prognostic assessment and therapeutic decision making in difficult endometrial carcinomas.

Neoadjuvant and Adjuvant Chemotherapy in Resected Pulmonary Large Cell Neuroendocrine Carcinomas: A Single Institution Experience

BACKGROUND Pulmonary large cell neuroendocrine carcinomas (LCNEC) are aggressive neoplasms with poor prognosis. The role of neoadjuvant and adjuvant therapies in these tumors remains uncertain. METHODS We performed a retrospective review of a prospective database. Kaplan-Meier estimates of overall survival (OS) were determined and compared across prognostic factors using log-rank analysis and the Cox proportional hazards model. RESULTS One hundred patients with resected LCNEC were identified from 1992 to 2008. Of these, 54% were male and 98% current or former smokers (mean 60.3 pack-years). Twenty-two patients received neoadjuvant platinum chemotherapy with a response rate of 68% (15 of 22). Eighty percent (80 of 100) underwent lobectomy and 11% (11 of 100) pneumonectomy with a 90% (90 of 100) complete resection (R0) rate. Seventy-one percent (71 of 100) were stage I-II, and 20 of 71 received platinum adjuvant chemotherapy. Mean OS was 40 months. Univariate factors associated with decreased OS included male gender (p = 0.007), increasing tumor (T) stage (p = 0.004), and stage III-IV disease (p = 0.04). Stage IB patients fared significantly worse than IA (p = 0.006). Multivariate analyses identified male gender (hazard ratio [HR] 2.3, p = 0.007), comorbid pulmonary disease (HR 2.3, p = 0.012), and pathologic stage (HR = 2.2, p = 0.011) as associated with risk of death. Univariate analysis in stage IB-IIIA completely resected (R0) patients receiving combination platinum-based induction and (or) adjuvant chemotherapy showed a trend toward improved OS (median survival 7.4 vs 2 years, p = 0.052). CONCLUSIONS The LCNEC has a high response rate to platinum-based neoadjuvant chemotherapy. Resected advanced-stage patients receiving combination neoadjuvant and (or) adjuvant chemotherapy may have a survival advantage. These therapies should be considered in resectable patients with LCNEC.

PAX-5 expression in pulmonary neuroendocrine neoplasms: its usefulness in surgical and fine-needle aspiration biopsy specimens.

The World Health Organization classification of lung tumors recognizes 4 histologic subtypes of pulmonary neuroendocrine carcinomas (NECs), which include typical carcinoids (TCs), atypical carcinoids (ACs), small cell carcinomas (SCCs), and large cell NECs (LCNECs). These tumors can be misclassified owing to morphologic parallels, indicating the necessity for adjunctive tests for correct classification. We evaluated immunohistochemical expression of PAX-5 in histologic and fine-needle aspiration (FNA) specimens of pulmonary NECs. Staining was stratified by intensity (0 to 3+) and percentage of cells stained as focal (<10%) or diffuse (=10%). PAX-5 expression was present in 29/37 (78%) of high-grade NECs (22/26 SCCs, 1/2 LCNECs, and 6/9 combined tumors) and none of 51 TCs and ACs; FNA specimens showed concordant staining. This study confirmed that PAX-5 is a useful marker in FNA and surgical specimens for the discrimination of low- to intermediate-grade NECs from high-grade NECs with 100% specificity and 79% sensitivity in surgical specimens.

Adherence of published diabetes mellitus practice guidelines to methodologic standards of guideline development

There are multiple practice guidelines published pertaining to diabetes care. Experts have formulated methodologic standards of guideline formulation. To determine whether practice guidelines pertaining to diabetes and published in peer-reviewed publications and the Internet adhered to established methodologic standards of guideline development. We identified all guidelines pertaining to diabetes care published between 1980 and 2000 using a computerized search of Medline, the Practice Guidelines Clearinghouse, the Institute for Clinical Systems Improvement Web site, and a global internet search engine. We used a previously validated 25-item assessment tool to determine guideline adherence to methodologic standards in three categories: guideline development and format, identification and summary of evidence, and formulation of recommendations. We conducted a multivariable regression analysis to determine the influence of guideline author, publishing medium, year of publication, and guidelines length on adherence to methodologic standards of guideline development. We evaluated 43 guidelines: 33% published on the Internet, 66% in peer-reviewed journals; 51% published by organizations, and 49% by individual experts. Of a maximum of 25 methodologic standards, the number of standards adhered by a guideline was 9 (range, 2 to 19). Mean proportion (SD) of guidelines that adhered to methodologic standards on guideline development and format was 48% (28); on identification and summary of evidence, 21% (22); and on the formulation of recommendations, 36% (27). Longer guidelines had greater adherence to methodologic standards (P < 0.0001). Guidelines pertaining to diabetes care published on the internet and in peer-reviewed publications do not meet most methodologic standards of guideline development.