Strong CD8+ lymphocyte infiltration in combination with expression of HLA class I is associated with better tumor control in breast cancer patients treated with neoadjuvant chemotherapy.

PURPOSE: Tumor-infiltrating lymphocytes (TILs) are associated with pathological complete response (pCR) and survival after neoadjuvant chemotherapy (NAC) in patients with early breast cancer. We investigated the prognostic and predictive role of TILs, macrophages, and HLA class 1 expression after NAC with or without the potentially immune modulating compound zoledronic acid (ZA). METHODS: Baseline tumor biopsies from 196 patients in the NEOZOTAC trial were analyzed for CD8 (cytotoxic T-cells), FoxP3 (regulatory T-cells), CD68 (macrophages), and HLA class I (HCA2/HC10) expression by immunohistochemistry and subsequently related to pCR and disease-free survival (DFS). RESULTS: A strong intratumoral CD8+ infiltration or expression of HLA class 1 by cancer cells was associated with a higher pCR rate (p < 0.05). Clinical benefit of high CD8+ T-cell infiltration was found when cancer cells expressed HLA class 1 (pCR: 21.8% vs. 6.7%, p = 0.04) but not when HLA class 1 expression was lost or downregulated (pCR: 5.9% vs. 0%, p = 0.38). Interaction analyses revealed survival benefit between HLA class 1 expression and strong CD8+ T-cell infiltration, whereas in the absence or downregulation of HLA class 1 expression, high levels of CD8+ T-cells were associated with survival disadvantage (p for interaction 0.01; hazard ratio 0.41, 95% CI 0.15-1.10, p = 0.08 and hazard ratio 7.67, 95% CI 0.88-66.4, p = 0.07, respectively). Baseline immune markers were not related to ZA treatment. CONCLUSIONS: Strong baseline tumor infiltration with CD8+ T-cells in the presence of tumoral HLA class 1 expression in patients with HER2-negative breast cancer is related to a higher pCR rate and a better DFS after NAC.

Expression of cell adhesion molecules and prognosis in breast cancer.

BACKGROUND: Cell adhesion molecules (CAMs) play an important role in the process of metastasis. The prognostic value of tumour expression of N-cadherin, E-cadherin, carcinoembryonic antigen (CEA) and epithelial CAM (Ep-CAM) was evaluated in patients with breast cancer. METHODS: A tissue microarray of the patient cohort was stained immunohistochemically for all markers and analysed by microscopy. Expression was classified into two categories, with the median score as cut-off level. For CEA, the above-median category was further subdivided in two subgroups based on staining intensity (low or high intensity). RESULTS: The cohort consisted of 574 patients with breast cancer with a median follow-up of 19 years. Below-median expression of E-cadherin (P = 0·015), and above-median expression of N-cadherin (P = 0·004), Ep-CAM (P = 0·046) and CEA (P = 0·001) all resulted in a shorter relapse-free period. Multivariable analysis revealed E-cadherin and CEA to be independent prognostic variables. Combined analysis of CEA and E-cadherin expression showed a 3·6 times higher risk of relapse for patients with high-intensity expression of CEA, regardless of E-cadherin expression, compared with patients with below-median CEA and above-median E-cadherin tumour expression (hazard ratio 3·60, 95 per cent confidence interval 2·12 to 6·11; P < 0·001). An interaction was found between expression of these two CAMs (P < 0·001), suggesting a biological association. CONCLUSION: Combining E-cadherin and CEA tumour expression provides a prognostic parameter with high discriminative power that is a candidate tool for prediction of prognosis in breast cancer.

The development of novel mouse monoclonal antibodies against the CC531 rat colon adenocarcinoma.

In this paper we describe 4 new monoclonal antibodies to be applied in rat models for cancer. The monoclonal antibodies were obtained by immunizing Balb/c mice with CC531 rat colon adenocarcinoma cells. Hybridomas were produced and 4 were selected for their reactivity with CC531 in vitro (MG1, 2, 3 and 4). All 4 antibodies recognized other rat tumour cell lines and showed limited cross-reactivity with normal rat tissues. Intraperitoneally injected MG1, 2 and 4 homed to in vivo growing, artificially induced CC531 liver metastases. In these in vivo experiments, limited cross-reactivity with normal rat tissues, predominantly of the gastro-intestinal tract, was found. MG4 was found to enhance lysis of CC531 tumour cells mediated by IL-2 activated, cultured natural killer cells. These antibodies are potentially useful for antibody-based laboratory techniques and for investigation of antibody-based immunotherapy of cancer in a rat model.

The microscopic anatomy of experimental rat CC531 colon tumour metastases: consequences for immunotherapy?

The colon adenocarcinoma cell line CC531 was adopted as a model for immunotherapeutical treatment of experimental colorectal metastases in a syngeneic rat model. We studied the presence and localization of T and natural killer cells, vessels and matrix proteins in in vivo growing CC531 tumours by immunohistochemistry. CC531 tumours were induced either in the lungs by injecting CC531 tumour cells into a tail vein or in the liver by injection of CC531 tumour cells under the liver capsule or into a mesenteric vein. All 3 tumour types were composed of islets of tightly apposed tumour cells surrounded by abundantly present tumour-stroma which contained tumour vessels and matrix proteins. Some of these matrix proteins, especially laminin and collagen IV formed a basal membrane-like structure around the tumour nodules. This structure was most pronounced in mesenteric vein-induced liver tumours and less prominent in subcapsular-induced liver tumours and tail vein-induced lung tumours. Tumour-infiltrating lymphocytes of both T and natural killer cell origin were found in the tumours, but predominantly in the tumour stroma, separated from the islets of tumour cells by the basal membrane-like structure. We hypothesize that the matrix proteins of these tumours play an ambivalent role: they may provide a substratum for migration of effector cells into the tumour stroma but may also provide a barrier preventing direct contact between tumour target cells and immune effector cells.

The role of MHC class I expression in rat NK cell-mediated lysis of syngeneic tumor cells and virus-infected cells.

In this study the role of MHC class I antigen expression in rat natural killer (NK) cell-mediated lysis was investigated. Various rat tumor cell lines and two Adenovirus (Ad)-transformed rat cell lines were tested for their expression levels of total MHC class I and two MHC class I alleles, RT1.A and RT1.C, by flow cytometry. Their susceptibility to NK cell-mediated lysis in relation to MHC class I expression was determined by 51Cr release assays. IFN-gamma is know to increase the expression of MHC class I. Therefore target cell with and without prior IFN-gamma treatment were examined for MHC class I expression and its effect on NK lysis. An significant inverse exponential relationship was found. To investigate the effect of virus infection on MHC class I expression and target cell lysis by NK cells, rat embryonal fibroblasts (REF) were infected with cytomegalovirus (CMV) and used as target cells for NK cell-mediated lysis. Results showed that these virus-infected cells were less susceptible to NK lysis than non-infected cells. Moreover, the non-infected cells expressed less MHC class I than the infected cells, indicating that also in this case, there was an inverse correlation between MHC class I expression and susceptibility to lysis by NK cells. Subsequently, we showed that sorted subsets of predominantly CD8-positive and CD8-negative NK cells lysed a MHC class I-positive tumor cell line at the same level. This suggests that CD8 is not likely to participate as a receptor for MHC class I in NK cell-mediated lysis in a syngeneic rat model.

The development of a bi-specific anti-CD161A x anti-tumor antibody for rat NK cell targeting.

In order to improve the therapeutic efficacy of adoptive immunotherapy of cancer using IL-2-activated NK (A-NK) cells, we developed a bi-specific monoclonal antibody (BimAb) 3.2.3xCC52. One specificity of the BimAb (mAb 3.2.3) was directed against rat CD161A (NKR-P1A) which has been shown to be an activation structure on rat NK cells involved in lysis of target cells and cytokine secretion. The other specificity (mAb CC52) was directed against a tumor associated antigen on the rat colon adenocarcinoma cell line CC531. The hybridomas producing 3.2.3 and CC52 were fused, resulting in a quadroma producing the desired 3.2.3xCC52 BimAb. The hybridomas produced antibodies of different isotypes (IgG2b and IgG1 respectively) which enabled us to pre-select quadromas with a high likelihood for production of BimAb, through testing for the production of bi-isotypic antibodies. Production of functional BimAb by the selected quadromas was demonstrated in an assay showing enhanced conjugate formation between CD161A+ cells and CC531 tumor cells. We also tested the 3.2.3xCC52 BimAb for its capacity to enhance NK cell-mediated lysis of CC531 tumor cells in 4 h and 19 h 51Cr release assays; in a prolonged (2 day) tumor neutralization assay using a tetrazolium salt (MTT)-based assay; and in tests for apoptosis using Annexin V-FITC. Although this BimAb was not demonstrated to cause enhanced lysis of CC531 cells by CD161A+ effector cells in vitro, it might be a useful tool to enhance the number of NK cells at the tumor site and/or prolong contact between tumor cells and NK cells in vivo, thereby probably enhancing the therapeutic efficacy of NK cells.

NK cells modulate MHC class I expression on tumor cells and their susceptibility to lysis.

Cytotoxicity and production of cytokines are two important functions of NK cells. These two different NK functions were studied in a syngeneic rat model in relation to MHC class I expression. We focussed on the mechanism by which NK cells modulate MHC class I expression on target cells and how this interferes with NK cell-mediated lysis. Using transfection experiments an inhibitory role on NK cell cytotoxicity for expression of target cells of RT1.A, rat MHC class I, was found. Co-culturing syngeneic tumor cells and NK cells resulted in enhanced MHC class I expression on the surviving tumor cell fraction, which was less susceptible to NK lysis. Increased tumor cell MHC class I was due to production of a soluble factor by NK cells, most likely interferon gamma. The regulatory function of NK cells shows here, that the enhancing of MHC class I expression on tumor cells in vitro and in vivo, results in downregulation of their target cell killing, but at the same time may facilitate the cytotoxic T cell function.

Expression of CD46, CD55, and CD59 on renal tumor cell lines and their role in preventing complement-mediated tumor cell lysis.

Nucleated cells are protected from complement-mediated injury by the expression of membrane-bound regulators of complement activation (mRCA) CD46, CD55, and CD59. Increased expression of these mRCA may be a mechanism by which tumor cells protect themselves from complement-mediated injury and prevent an inflammatory response. In the present study, we have investigated whether human renal tumor cell lines and cultured proximal tubular epithelial cells express CD46, CD55, and CD59 and whether these mRCA influence complement-mediated lysis of these cells. The expression of CD46, CD55, and CD59 was measured by flow cytometry. To determine the effect of mRCA on lysis, tumor cells were opsonized with complement activating anti-HLA class l mAb. Lysis was measured in the presence or absence of anti-CD46, anti-CD55 or anti-CD59 mAb and serum as a source of complement, using a 51Cr release assay. Flow cytometric analysis revealed that renal tumor cell lines and proximal tubular epithelial cells all express CD46, CD55, and CD59. Lysis of renal tumor cell lines in the presence of rabbit serum depended on the number of HLA class I molecules expressed by the tumor cells. Using human serum, complement-mediated lysis was decreased by at least one-third as compared with rabbit serum. The susceptibility of renal tumor cells for complement-mediated lysis could be increased up to the level observed with rabbit serum by inhibiting the function of CD59. Inhibition of the function of CD46 or CD55 with mAb directed against these mRCA had no substantial effect on lysis. We conclude from this work that renal tumor cells and proximal tubular epithelial cells express CD46, CD55, and CD59. Of these mRCA, CD59 is most efficient in preventing complement-mediated lysis of these cells. Expression of mRCA on tumor cells may influence the effectiveness of immunotherapy with tumor-associated mAb.

Administration of BiMAb-retargeted T cells in a rat hepatic metastases colon tumour model results in T-cell tumour infiltration independent of the route of administration.

In this study, cultured T cells, pre-incubated with the bispecific monoclonal antibody (BiMAb) R73IgG1 x CC52IgG1 were adoptively transferred, via systemic and regional routes, to rats bearing day 10 hepatic metastases of the CC531 adenocarcinoma of the colon to investigate the role of the route of administration in tumour infiltration by these BiMAb-retargeted effector cells. The BiMAb, directed against the T-cell receptor and the tumour-associated antigen CC52, were used to crosslink CC531 tumour cells and T cells to induce tumour cell lysis. Retargeted T cells were administered via the jugular vein, hepatic artery or the portal vein. The number of BiMAb-retargeted T cells that reached the liver tumours was independent of the route of administration. There was also no difference between the number of T cells that reached the portal tracts, central veins of parenchyma of the liver, after loco-regional or systemic administration. These findings are in contrast to the interleukin (IL)-2 activated NK (A-NK) cells biodistribution studies earlier performed in the same animal model in our laboratory. Compared with A-NK cells, a lower number of BiMAb-retargeted T cells reached the tumours, irrespective of their route of administration while for A-NK cells, there was an advantage of administration via the hepatic artery.

Endogenous natural killer cells do not play a role in antitumor effects induced by interleukin-2 in a syngeneic rat colon tumor model.

Previous experiments in a syngeneic rat liver tumor model using the colon adenocarcinoma CC531 demonstrated that injection of interleukin-2 (IL-2) induced significant antitumor responses. Furthermore, it was found that this treatment strategy was accompanied by an increase in the number of natural killer (NK) cells in and around the tumor. In the present study, the role of endogenous NK cells in IL-2-mediated antitumor responses was further elucidated by depleting tumor-bearing rats of NK cells, using the anti-CD161A mouse IgG1 antibody 3.2.3. Rats were depleted either after or prior to tumor induction and subsequently treated with IL-2. The results demonstrated that depletion of NK cells in tumor-bearing rats did not influence IL-2-induced antitumor effects. In addition, injection of IL-2 in NK-cell-depleted rats induced repopulation of NK cells in the peripheral blood from 3 days on and further after the last injection with IL-2. Therefore, the possibility cannot be excluded that de novo recruited NK cells play a role in attaining IL-2 mediated antitumor effects, but NK cells, which were present before or during the start of IL-2 therapy, were not relevant.

Regional administration of natural killer cells in a rat hepatic metastasis model results in better tumor infiltration and anti-tumor response than systemic administration.

A syngeneic rat liver metastasis model, the CC531 colon carcinoma cell line in Wag rats, was used to study the homing properties and anti-tumor effects of adoptively transferred, interleukin-2 (IL-2)-activated, cultured natural killer (A-NK) cells. To identify the route of administration that gives the highest tumor infiltration, 1.5 x 10(8) A-NK cells were dyed with fluorescent rhodamine and injected via 4 different routes into rats, bearing subcapsularly induced (day 10) liver metastases. The routes chosen were: jugular vein, portal vein, hepatic artery and directly into the peritoneal cavity (i.p). The rats were sacrificed 20 hr after administration of A-NK cells. The highest (p < 0.05) infiltration of tumors by A-NK cells was found both at the tumor border and in the tumor center after injection via the hepatic artery: 65 +/- 7 A-NK cells/mm2 at the tumor border and 26 +/- 14 A-NK cells/mm2 in the center of the tumor (jugular vein infusion: 32 +/- 10 and 9 +/- 5 A-NK cells/mm2, respectively; portal vein infusion: 36 +/- 13 and 7 +/- 4 A-NK cells/mm2, respectively). No A-NK cells were detected in the liver after i.p. injection. Rats bearing day 5 tumors were injected with 1.5 x 10(8) A-NK cells via the hepatic artery or via the jugular vein (n = 5 and n = 6 respectively). Regional administration of A-NK cells via the hepatic artery resulted in a significant (p < 0.05) lower weight (35 +/- 23 mg) of tumors than did systemic administration (70 +/- 10 mg). Our results suggest that both the level of tumor infiltration by adoptively transferred A-NK cells and the therapeutic outcome depend on the route of administration.

Characteristics of tumor infiltration by adoptively transferred and endogenous natural-killer cells in a syngeneic rat model: implications for the mechanism behind anti-tumor responses.

Interleukin-2-activated, cultured NK cells (A-NK) cells were adoptively transferred into a syngeneic rat liver-tumor model. The kinetics of tumor infiltration by NK cells, originating either from adoptively transferred or from endogenous sources, the localization of these cells in the tumor, and their interactions with extracellular-matrix proteins were studied by immunohistochemistry and transmission-electron microscopy. The adoptive transfer of A-NK cells via the hepatic artery and s.c. injections of IL-2 into rats bearing subcapsularly induced CC531 liver tumors, but also IL-2 monotherapy, resulted in a significant increase of the number of NK cells both at the tumor border and in the tumor center. The majority of tumor-infiltrating NK cells was present in the tumor stroma and only occasionally was an NK cell observed in a tumor nodule in direct contact with tumor cells. Observations by electron microscopy suggested that matrix proteins, abundantly present in the tumor stroma but absent in the tumor nodules, provide a substrate for migration of infiltrating cells, whereas tight structures of matrix proteins surrounding tumor nodules provide a barrier for establishment of direct NK-cell-to-tumor-cell-contact. Our results suggest that direct NK-cell-to-target-cell-contact-mediated lysis is of minor importance for attaining an anti-tumor effect in this model. We hypothesize that treatment of tumor-bearing rats with A-NK cells and/or IL-2 initiates a cascade of events (e.g., secretion of tumor-killing cytokines and/or infiltration of other immune cells) ultimately leading to tumor regression.

The phenotypic heterogeneity of human natural killer cells: presence of at least 48 different subsets in the peripheral blood.

Peripheral blood natural killer (NK) cells are usually defined as a homogeneous cell population. However, NK cells show heterogeneous expression of a diversity of cell surface molecules, which might reflect the diversity of NK-cell functions. Therefore, a more specific phenotypic definition of NK cells is necessary. In this study, we made an inventory of phenotypic subsets that are present within the peripheral blood NK-cell population of healthy donors based on differential expression of nine cell-surface markers. Using three-colour flow cytometric analysis we were able to define at least 48 different CD56(+) NK-cell subsets within the peripheral blood. This phenotypic heterogeneity appeared to be stable among healthy individuals, and was also steady within CD56(dim) and CD56(bright) NK populations, indicating a possible role for these subsets in NK-cell function or differentiation.

Caspase-3 activity as a prognostic factor in colorectal carcinoma.

Several techniques to determine apoptotic frequencies in tumors have been described. In this study, we report that biochemical detection of enzymatic caspase-3 activity is a simple and quantitative technique to measure apoptosis in colorectal tumor cells. The relevance of the level of apoptosis in colorectal cancer for the clinical course remains unclear. Therefore, we studied the correlation between caspase-3 activity and prognosis of the disease in relation to different factors known to be involved in apoptosis induction. High caspase-3 activity significantly correlated with a higher risk of recurrence and was preferentially found in tumors of the right side of the colon. No correlation was detected between high caspase-3 activity and altered protein expression of p53, beta-catenin, or proteins of mismatched repair genes. This indicates that high caspase-3 activity has no evident correlation with the genetic Wnt-signaling or the mismatch repair mutational pathways. The caspase-3 activity significantly correlated with CD57(+) tumor infiltrating cells. Therefore, high caspase-3 activity in right-sided tumors might be induced by a specific lymphocytic reaction.

Recombinant adenoviral vectors have adjuvant activity and stimulate T cell responses against tumor cells.

The host-immune response against adenoviruses forms a major obstacle for their use as gene therapy vectors for treatment of genetic defects. None the less, they are the preferred vectors for in vivo gene transfer in experimental gene therapy protocols for cancer. In this article we demonstrate the antitumor efficacy of adenovirus-mediated transfer of human interleukin-2 cDNA in the rat-CC531 model for hepatic metastases of colorectal cancer: intratumoral administration of 10 plaque-forming units of the hlL-2-expressing adenoviral vector, AdCAIL-2, resulted in a cessation of tumor growth in 80% of the injected tumors. In control groups receiving AdCnull, a vector with the same viral backbone, but lacking transgene expression, none of the tumors responded. However, intratumoral treatment with this vector significantly enhanced tumor regression induced by systemic IL-2 protein treatment, which was used as a positive control. In addition we show, by performing delayed-type of hypersensitivity assays, that AdCnull when injected intratumorally enhances recognition of tumor antigens by T lymphocytes to the same extent as intratumoral treatment with the IL-2-expressing vector. The replication-deficient adenoviruses appear to have a therapeutic advantage in cytokine-mediated immunotherapy: even adenovirus vectors that do not express a transgene, show adjuvant activity and stimulate an antitumor immune response.

Dendritic cells in colorectal cancer correlate with other tumor-infiltrating immune cells.

Dendritic cells (DCs) are the most efficient antigen-presenting cells and play a key role in a cellular antitumor immune response. In this study we investigated the exact localization of DCs within colorectal tumors and their relationship to tumor-infiltrating lymphocytes as well as clinical outcome of the patients. Primary tumor specimens of 104 patients with a diagnosis of colorectal cancer were identified retrospectively and analyzed with the dendritic cell markers S-100 protein and human leukocyte antigens (HLA) class II. The markers were individually combined with laminin as a second marker to facilitate the observation of the different tumor localizations. S-100 or HLA class II positive cells were found in the three different compartments of colorectal tumors: tumor epithelium, tumor stroma, and advancing tumor margin, but mainly present in tumor stroma and advancing tumor margin. S-100-positive tumor-infiltrating DCs in direct contact with tumor cells, i.e., in tumor epithelium, significantly correlated to the intraepithelial infiltration of CD4+ (p=0.02) and CD8+ (p=0.01) lymphocytes. High HLA class II+ cell infiltration in the tumor stroma correlated to a lower intraepithelial infiltration of CD8+ (p=0.02) lymphocytes. High intraepithelial infiltration of S-100-positive DCs suggested increased disease-free survival, but was not statistically significant, while high amounts of HLA class II+ cells in the tumor stroma correlated with an adverse survival outcome. Our results show that the infiltration of DCs in colorectal cancer, depending on both location and type of marker, is correlated with local immune interactions and patient prognosis, suggesting a central role for DCs in controlling local tumor immunity.