Development of Vaccines for High-Risk Ductal Carcinoma In situ of the Breast

With the widespread use of screening mammography, ductal carcinoma in situ (DCIS) has become the most frequently diagnosed cancerous lesion identified in the breast. Like invasive breast cancer, DCIS is heterogeneous and represents a relatively wide spectrum of diseases.

Low-grade DCIS either rarely develops into invasive disease or progresses slowly to invasiveness over the course of 8 to 10 years. On the other hand, if untreated, high-grade DCIS lesions that display comedonecrosis will likely develop into invasive breast cancers over a 5- to 7-year period. Following current conventional treatment with surgery with wide margins (lumpectomy; ref. 1), lumpectomy plus radiation therapy (2), or mastectomy, the overall prognosis for these patients is excellent. Nonetheless, many patients (at least 30%) require the more aggressive therapeutic option (mastectomy) either because of extensive disease or for fear of cancer recurrence.

The latter remains a significant risk, particularly in younger patients. Fortunately, the relatively long period of latency between the onset of DCIS and development of invasive breast cancer offers an opportunity for novel neoadjuvant interventions. The potential benefits of such neoadjuvant therapies include (a) reduction of risk for subsequent breast cancer, (b) reduction in the psychological effect of the disease related to fear of recurrence, and (c) reduction in the morbidity resulting from surgery and radiation.

The latter would be achieved through diminution in the extent of disease before the application of standard therapies, limiting the need for radiation and decreasing the need for extensive surgical
resections.

Breast Cancer Developments

Over-expression of the HER2/neu receptor occurs in 20 to 30 percent of breast tumors and is linked to poorer prognosis. The HER2/neu expression status determines whether or not patient will receive trastuzumab-based treatment. In clinical practice, over-expression of HER2/neu is routinely identified using Immunohistochemistry (IHC) or Fluorescence in Situ Hybridization (FISH), both of which are invasive approaches requiring tissue samples. Serum assays for the Extra Cellular Domain of HER2/neu receptor (HER2 ECD) have been reported but the use is very limited due to serum interference factors (e.g. human anti-animal immunoglobulin antibodies) that lead to false test results and inconsistency with tissue Her2 status. We have developed an ELISA based approach using an MBB buffer to eliminate false results and to obtain more accurate assessment of HER2 ECD levels. Using this refined assay we retroactively measured HER2/neu levels from breast cancer patients and controls. Abnormal HER2 ECD levels were detected in about 32% of invasive breast cancer patients but not in controls or patients with benign diseases. In addition, we also showed that patients with elevated serum HER2 levels appeared to have worse survival regardless of treatments. In a small group of 12 Ductal Carcinoma in situ (DCIS) patients who received HER2/neu peptide vaccination and surgery, only one patient showed constantly rising HER2 levels after treatment and this patient had recurrence of HER2 positive tumor within 5 years. Our studies indicate that once the serum interference issue is resolved, serum HER2 ECD can have potential clinical utility to supplement the tissue based tests.

Affiliation

Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, U.S.A.

New Developments with T-Cells

The ErbB2 protein is a member of the tyrosine kinase family of growth factor receptors that is overexpressed in cancers of the breast, ovary, stomach, kidney, colon, and lung, and therefore represents an attractive candidate antigen for targeted cancer immunotherapy. Cytotoxic T lymphocytes specific for various immunogenic ErbB2 peptides have been described, but they often exhibit both poor functional avidity and tumor reactivity. In order to generate potent CD8(+) T cells with specificity for the ErbB2(369-377) peptide, we performed one round of in vitro peptide stimulation of CD8(+) T cells isolated from an HLA-A2(+) patient who was previously vaccinated with autologous dendritic cells pulsed with HLA class I ErbB2 peptides. Using this approach, we enriched highly avid ErbB2-reactive T cells with strong ErbB2-specific, antitumor effector functions. We then stimulated these ErbB2-reactive T cells with ErbB2(+) HLA-A2(+) tumor cells in vitro and sorted tumor-activated ErbB2(369-377) peptide T cells, which allowed for the isolation of a novel T-cell receptor (TCR) with ErbB2(369-377) peptide specificity. Primary human CD8(+) T cells genetically modified to express this ErbB2-specific TCR specifically bound ErbB2(369-377) peptide containing HLA-A2 tetramers, and efficiently recognized target cells pulsed with low nanomolar concentrations of ErbB2(369-377) peptide as well as nonpulsed ErbB2(+) HLA-A2(+) tumor cell lines in vitro. In a novel xenograft model, ErbB2-redirected T cells also significantly delayed progression of ErbB2(+) HLA-A2(+) human tumor in vivo. Together, these results support the notion that redirection of normal T-cell specificity by TCR gene transfer can have potential applications in the adoptive immunotherapy of ErbB2-expressing malignancies.

Affiliation

1 Ovarian Cancer Research Center, Department of Obstetrics and Gynecology, University of Pennsylvania , Philadelphia, PA 19104.