HLA-Dr Expression by Tumor Cells Compared with Survival in High Grade Astrocytomas

Therapeutic applications of the selective high affinity ligand drug SH7139 extend beyond non-Hodgkin's lymphoma to many other types of solid cancers

SH7139, the first of a series of selective high affinity ligand (SHAL) oncology drug candidates designed to target and bind to the HLA-DR proteins overexpressed by B-cell lymphomas, has demonstrated exceptional efficacy in the treatment of Burkitt lymphoma xenografts in mice and a safety profile that may prove to be unprecedented for an oncology drug. The aim of this study was to determine how frequently the HLA-DRs targeted by SH7139 are expressed by different subtypes of non-Hodgkin’s lymphoma and by other solid cancers that have been reported to express HLA-DR. Binding studies conducted with SH7129, a biotinylated analog of SH7139, reveal that more than half of the biopsy sections obtained from patients with different types of non-Hodgkin’s lymphoma express the HLA-DRs targeted by SH7139. Similar analyses of tumor biopsy tissue obtained from patients diagnosed with eighteen other solid cancers show the majority of these tumors also express the HLA-DRs targeted by SH7139. Cervical, ovarian, colorectal and prostate cancers expressed the most HLA-DR. Only a few esophageal and head and neck tumors bound the diagnostic. Within an individual’s tumor, cell to cell differences in HLA-DR target expression varied by only 2 to 3-fold while the expression levels in tumors obtained from different patients varied as much as 10 to 100-fold. The high frequency with which SH7129 was observed to bind to these cancers suggests that many patients diagnosed with B-cell lymphomas, myelomas, and other non-hematological cancers should be considered potential candidates for new therapies such as SH7139 that target HLA-DR-expressing tumors.

Lack of B7 expression, not human leukocyte antigen expression, facilitates immune evasion by human malignant gliomas

OBJECTIVE

Lack of human leukocyte antigens and costimulatory molecules have been suggested as mechanisms by which human malignant gliomas avoid immune recognition and elimination.

METHODS

Using quantitative multiparameter flow cytometric analysis, tumor cells from patients with glioblastoma multiforme (n = 18) were examined ex vivo for the expression of human leukocyte antigen Class I and II molecules and the costimulatory molecules B7-1 and B7-2. They were compared with reactive astrocytes from peritumoral brain metastases (n = 7), and astrocytes removed during nontumor surgery (n = 5).

RESULTS

In contrast to the vast majority of solid peripheral human tumors, these results demonstrate that glioblastoma multiforme frequently express both human leukocyte antigen Class I and II molecules. Like most solid peripheral tumors, glioblastoma multiforme tumor cells express few or no B7 costimulatory molecules. Functional assays using heterogeneous ex vivo tumor preparations or pure populations of ex vivo tumor cells and microglia obtained using fluorescence-activated cell sorting indicate that CD4+ T-cells are activated by tumor cells only in the presence of exogenous B7 costimulation (provided by addition of soluble agonist anti-CD28 monoclonal antibody).

CONCLUSION

Thus, in contrast to many solid peripheral tumors, failure to present tumor antigens is not a likely impediment to immunotherapeutic strategies against malignant gliomas. Rather, immunotherapeutic strategies need to overcome low levels of B7 costimulation.

Long-term survival of a patient with giant cell glioblastoma. Case report

The authors report on a patient who had undergone resection of a left-sided temporal giant cell glioblastoma at the age of 69 years and who survived for more than 17 years. This man had not undergone postoperative radiotherapy or adjuvant chemotherapy. He died at the age of 86 years without clinical evidence of tumor recurrence. Histologically, the lesion was characterized by highly pleomorphic tumor cells (including bizarre multinucleated giant cells) with high mitotic activity, large necroses, and prominent mononuclear infiltration. A point mutation in the TP53 tumor suppressor gene (c.524G>A; R175H) and no epidermal growth factor receptor gene amplification were revealed on molecular genetic analysis. No diagnostic chromosomal imbalances were identified on comparative genomic hybridization, although the average ratio profile for chromosome 10 indicated loss of 10p15 in a subpopulation of tumor cells. This patient is exceptional because tumor resection, probably in conjunction with a marked antitumor immune response, apparently resulted in eradication of the lesion.

Differential expression of MHC class II molecules by microglia and neoplastic astroglia: relevance for the escape of astrocytoma cells from immune surveillance

There is increasing evidence that microglia serve as antigen presenters in the human CNS. Although the occurrence of MHC class II immunoreactive cells has been reported in astrocytic gliomas, the relative contribution of microglia to this cell population has not been studied in detail. Using computer-assisted image analysis, we have investigated the expression of MHC class II molecules and of the microglia/macrophage markers Ki-MIP, RCA-1, KP1 and iba1, in 97 astrocytic gliomas comprising all WHO grades to answer the question whether there is a correlation between tumour grade and the number of MHC class II positive microglia/macrophage profiles. Microglia expressing MHC class II were common in astrocytomas and anaplastic astrocytomas but rare in pilocytic tumours although there was significant variation within each group. MHC class II immunoreactivity was reduced in highly cellular areas of glioblastomas where large numbers of cells expressing macrophage markers were still present. Thus, there was no simple relationship between tumour grade and microglial/macrophage MHC class II expression. In addition, up to 55% of astrocytic gliomas contained MHC class II immunoreactive tumour cells. Microglia but not tumour cells were found to express the BB1/B7 costimulator. We conclude that microglia in astrocytic gliomas are well equipped to function as antigen presenting cells. Yet, neoplastic astroglia appear to acquire the capacity to downregulate microglial MHC class II expression and, at the same time, may induce T-cell clonal anergy through aberrant expression of MHC class II molecules.

Characterization of the mononuclear cell infiltrate and HLA-Dr expression in 19 oligodendrogliomas

We have studied frozen tissue from 19 oligodendrogliomas with a panel of antibodies to lymphocytes and their subsets, macrophages, natural killer cells, and HLA-Dr antigens. Macrophages were detected in moderate numbers in 60%-100% of tumors depending on the antibody used. T lymphocytes were fewer in number than macrophages and were present in 62% of cases. Most of the T lymphocytes were of the CD8 phenotype. CD4 lymphocytes were very few in number and present in only 18%. B cells and natural killer cells were absent from all cases. HLA-Dr antigens were expressed by macrophages in all cases but never on tumor cells. The implications of these findings are that macrophages and, to a lesser extent, CD8 lymphocytes are the predominant cells infiltrating oligodendrogliomas and that they may exert cellular immune functions.