Peter L. Stern

Implications for immunosurveillance of altered HLA class I phenotypes in human tumours

HLA class I downregulation is a frequent event associated with tumour invasion and development. Altered HLA class I tumour phenotypes can have profound effects on T-cell and natural killer (NK)-cell antitumour responses. Here, Federico Garrido and colleagues analyse these altered tumour phenotypes in detail, indicating their potential relevance for implementation of immunotherapeutic protocols and strategies to overcome tumour escape mechanisms.

Natural history of HLA expression during tumour development

HLA expression is frequently altered in tumours compared to the tissue from which they originate. Given the central role of MHC products in the restriction of T-cell recognition, regulation of tumour HLA expression might be a strategy for the evasion of immune surveillance by the malignant cells. Federico Garrido, Peter Stern and colleagues present data from a variety of tumour types, suggesting that HLA class I alterations may occur at a particular step between the development of an in situ lesion and an invasive carcinoma.

Epithelial-mesenchymal transition events during human embryonic stem cell differentiation.

Epithelial-mesenchymal transition (EMT) occurs during embryonic development and may also be associated with the metastatic spread of epithelial tumors. During EMT, E-cadherin is down-regulated and this correlates with increased motility and invasion of cells. We show that differentiation of human embryonic stem (ES) cells in monolayer culture is associated with an E- to N-cadherin switch, increased vimentin expression, up-regulation of E-cadherin repressor molecules (Snail and Slug proteins), and increased gelatinase (matrix metalloproteinases; MMP-2 and MMP-9) activity and cellular motility, all characteristic EMT events. The 5T4 oncofetal antigen, previously shown to be associated with early human ES cell differentiation, is also part of this process. Abrogation of E-cadherin-mediated cell-cell contact in undifferentiated ES cells using neutralizing antibody (nAb) SHE78.7 resulted in increased cellular motility, altered actin cytoskeleton arrangement and a mesenchymal phenotype together with presentation of the 5T4 antigen at the cell surface. nAb-treated ES cells remained in an undifferentiated state, as assessed by OCT-4 protein expression, and did not express EMT-associated transcripts. Removal of nAb from ES cells resulted in the restoration of cell-cell contact, absence of cell surface 5T4, decreased mesenchymal cellular morphology and motility, and enabled the differentiation of the cells to the three germ layers upon their removal from the fibroblast feeder layer. We conclude that E-cadherin functions in human ES cells to stabilize the cortical actin cyoskeletal arrangement and this prevents cell surface localization of the 5T4 antigen. Furthermore, human ES cells represent a useful model system with which to study EMT events relevant to embryonic development and tumor cell metastasis.

Prognostic significance of p53 overexpression in gastric and colorectal carcinoma.

p53 expression was examined in 55 gastric and 107 colorectal carcinomas with an immunoperoxidase technique, using the polyclonal antibody CM1 on routinely fixed, paraffin embedded tissue. p53 protein was detected in 47% gastric and in 46% colorectal carcinomas and found to correlate with stage of disease and unfavourable clinical outcome (P less than 0.001). Thus, the proportion of positively reacting neoplasms increased as the stage progressed, tumours which had invaded regional lymph-nodes overexpressed p53 more frequently than localised carcinomas and an elevated level of p53 was associated with early relapse and death. In colorectal carcinoma p53 positivity was also linked with site and macroscopic configuration of the primary tumour and was most frequently expressed in carcinomas from the rectum and in ulcerative tumours. p53 overexpression was irrespective of tumour grade. Uniform negative reactivity with anti-p53 antibody was seen in normal epithelium adjacent to carcinoma, intestinal metaplasia, atrophic gastritis and in colonic adenomas. There was a good correlation between immunohistochemical staining on paraffin and frozen sections. These studies suggest that in gastric and colorectal carcinoma, immunohistochemical detection of p53 protein in routinely fixed tissue can be used along with other established parameters to assess prognostic outcome, especially to identify patients with poor short-term prognosis.

The association of an HPV16 oncogene variant with HLA-B7 has implications for vaccine design in cervical cancer.

HLA-restricted cytotoxic T-lymphocyte (CTL) recognition of human papillomavirus (HPV) oncogene products may be important in the control of the HPV infections associated with the development of cervical cancer. We have identified, in HLA-B7 individuals, a consistent variation in the HPV16 E6 oncoprotein sequence, which alters an HLA-B7 peptide binding epitope in a way likely to influence immune recognition by CTLs. These results illustrate a biologically relevant mechanism for escape from immune surveillance of HPV16 in HLA-B7 individuals. Thus, both HLA type and HPV16 strain variation need to be considered in the screening of at-risk individuals and for the rational design of anti-HPV vaccines.

Phase II trial of imiquimod and HPV therapeutic vaccination in patients with vulval intraepithelial neoplasia

Background:Vulval intraepithelial neoplasia (VIN) is a premalignant condition, which is frequently associated with type HPV16 infection, and multifocal disease has high rates of surgical treatment failure.Methods:We report a phase II clinical trial of the topical immunomodulator, imiquimod, for 8 weeks, followed by 3 doses (weeks 10, 14 and 18) of therapeutic human papillomavirus (HPV) vaccination (TA-CIN, fusion protein HPV16 E6E7L2) in 19 women with VIN grades 2 and 3. Histology and HPV testing of biopsies were performed at weeks 0, 10, 20 and 52. Intralesional infiltration of T-cell subsets and lymphocyte proliferation for HPV systemic immune responses were also assessed.Results:Lesion response (complete regression of VIN on histology) was observed in 32% (6 out of 19) of women at week 10, increasing to 58% (11 out of 19) at week 20 and 63% (12 out of 19) at week 52. At this time, 36% (5 out of 14) of lesions showed HPV16 clearance and 79% (15 out of 19) of women were symptom free. At week 20, after treatment with imiquimod and vaccination, there was significantly increased local infiltration of CD8 and CD4 T cells in lesion responders; in contrast, non-responders (persistent VIN by histology) showed an increased density of T regulatory cells. After vaccination, only lesion responders had significantly increased lympho-proliferation to the HPV vaccine antigens.Conclusion:The therapeutic effect of treatment depends on the differential immune response of responders and non-responders with affect locally and systemically.

Frequency of down-regulation of individual HLA-A and -B alleles in cervical carcinomas in relation to TAP-1 expression

The development of cervical carcinoma is strongly associated with specific types of human papillomaviruses (HPVs). A role for cellular immunity in cervical disease is supported by the increased occurrence of HPV-associated lesions in immunosuppressed individuals. Upon viral infection or malignant transformation, ensuing alterations in gene expression result in the generation of novel sets of peptides which can form complexes with specific HLA class I heavy chains and beta 2-microglobulin. These are then expressed at the cell surface as potential targets for specific T cells. In this study of 100 carcinomas HLA-A and -B class I expression by the tumour cells was down-regulated at one or more alleles in at least 73% of cervical carcinomas. Interference with the transporter associated with antigen presentation (TAP), which translocates cytosolic peptides from endogenously synthesised proteins (e.g. viral) into the lumen of the endoplasmic reticulum was found in 38% of the HLA class I down-regulated tumours. Loss of expression for common HLA class I alleles ranged from 36% to 71%, and such changes might be expected to influence specific immunogenic peptide presentation and consequent immune recognition. These results underline the importance of single as well as multiple allelic loss in cervical neoplasia and have important implications for attempts to intervene immunologically in cervical cancer.

The role of extracellular spacer regions in the optimal design of chimeric immune receptors: evaluation of four different scFvs and antigens.

Human peripheral blood lymphocytes can be transduced to express antigen-dependent CD3ζ chimeric immune receptors (CIRs), which function independently of the T-cell receptor (TCR). Although the exact function of these domains is unclear, previous studies imply that an extracellular spacer region is required for optimal CIR activity. In this study, four scFvs (in the context of CIRs with or without extracellular spacer regions) were used to target the human tumor-associated antigens carcinoembryonic antigen (CEA), neural cell adhesion molecule (NCAM), the oncofetal antigen 5T4, and the B-cell antigen CD19. In all cases human T-cell populations expressing the CIRs were functionally active against their respective targets, but the anti-5T4 and anti-NCAM CIRs showed enhanced specific cytokine release and cytotoxicity only when possessing an extracellular spacer region. In contrast, the anti-CEA and anti-CD19 CIRs displayed optimal cytokine release activity only in the absence of an extracellular spacer. Interestingly, mapping of the scFv epitopes has revealed that the anti-CEA scFv binds close to the amino-terminal of CEA, which is easily accessible to the CIR. In contrast, CIRs enhanced by a spacer domain appear to bind to epitopes residing closer to the cell membrane, suggesting that a more flexible extracellular domain may be required to permit the efficient binding of such epitopes. These results show that a spacer is not necessary for optimal activity of CIRs but that the optimal design varies.

Immunological Responses in Women with Human Papillomavirus Type 16 (HPV-16)-Associated Anogenital Intraepithelial Neoplasia Induced by Heterologous Prime-Boost HPV-16 Oncogene Vaccination

Purpose: The purpose is to study the immunogenicity of heterologous prime-boost human papillomavirus (HPV) oncogene vaccination in patients with anogenital intraepithelial neoplasia (AGIN). Experimental Design: Twenty-nine women with high-grade AGIN received three i.m. doses of TA-CIN (HPV-16 L2/E6/E7 protein) at four weekly intervals followed by a single dermal scarification of vaccinia HPV-16/18 E6/E7 and were followed up for 12 weeks. Immunity to HPV-16 was assessed by lymphoproliferation, IFN-γ enzyme-linked immunospot (ELISPOT), and ELISA. Results: The patient group significantly responded to TA-CIN and not to the control antigen HPV-6 L2/E7 at all postvaccination time points when compared with baseline responses (P ≤ 0.05). Ten of the patients showed at least a 3-fold increase in TA-CIN-specific proliferation at one or more time points after vaccination. Comparison of stimulation with HPV-16 E6- or E7-GST fusion proteins showed that proliferative responses were biased to HPV-16 E6. This bias was also seen by IFN-γ ELISPOT using overlapping peptides, with HPV-16 E6- or E7-specific T cells being detected in 9 and 2 patients, respectively. In addition, vaccination resulted in the induction of antibodies against the HPV-16 oncoproteins. Of the 6 clinical responders, 2 patients showed both a proliferative TA-CIN-specific response and an E6-specific IFN-γ response, whereas 3 other patients displayed E6-specific reactivity only. Stable disease was recorded in 19 patients, 8 of whom showed a concomitant TA-CIN-specific proliferative and/or E6-specific T-cell response. Of the 4 progressors, 2 failed to make a T-cell response and 2 responded by either proliferation or E6 ELISPOT alone. Conclusions: The prime-boost regimen is immunogenic in AGIN patients (humoral and cellular immunity), but there is no simple relationship between induction of systemic HPV-16-specific immunity and clinical outcome. Other factors that may play a role in the eradication of long-term established AGIN lesions need to be determined to identify the patient group that would benefit from immunotherapy with the vaccines used in this study.

HPV 16 infection and progression of cervical intra‐epithelial neoplasia: Analysis of HLA polymorphism and HPV 16 E6 sequence variants

High‐risk human papillomavirus (HPV) infection plays an important role in cervical intra‐epithelial neoplasia (CIN), but HPV infection alone is not sufficient for progression to cervical cancer. Several lines of evidence suggest that cellular immune surveillance is important in the control of HPV infection and the development of CIN. The presentation to T cells of target viral peptides in the context of HLA molecules is influenced by the genetic polymorphisms of both HPV and HLA and thereby influences the host immune response and clinical outcome of HPV infection. HLA class I and II polymorphism in susceptibility for HPV 16 infection, development and progression of CIN was analyzed in a group of 118 patients participating in a prospective study of women with initial abnormal cytology. Patients were stratified according to HPV status and course of the disease. HLA‐B*44 frequency was increased in the small group of patients with a lesion that showed clinical progression during follow‐up [OR = 9.0 (4.6–17.5),p= 0.007]. HLA‐DRB1*07 frequency was increased among HPV 16‐positive patients compared with patients who were negative for all HPV types [OR = 5.9 (3.0–11.3), p= 0.02]. Our results are consistent with the immunogenetic factors associated with disease progression being different from those associated with susceptibility to HPV 16 infection. Sequencing of the HPV 16 E6 and E7 open reading frames of a subset of these patients (n = 40) showed the frequency of HPV 16 variants to be similar to other studies. However, there was no significant correlation between variant incidence and disease progression or viral persistence and no significant correlation with any HLA allele. It appears that multiple HLA types can influence HPV 16‐associated cervical dysplasia but the role of HPV 16 variants in disease progression and susceptibility in relation to HLA polymorphism remains unclear. Int. J. Cancer 78:166–171, 1998.© 1998 Wiley‐Liss, Inc.