Expression of immune checkpoint regulators, cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed death-ligand 1 (PD-L1), in female breast carcinomas

BACKGROUND

Immune checkpoint regulators, cytotoxic T lymphocyte antigen 4 (CTLA-4) and the programmed cell death protein-1/programmed death-ligand 1 (PD-1/PD-L1) have emerged as promising new targets for cancer therapeutics. While tumor expression of PD-L1 has been shown to have objective responses to anti-PD-L1 immunotherapies, the clinical implications of CTLA-4 expression in tumor cells or immune cells in the tumor microenvironment is still controversial. We investigated the expression of CTLA-4 and PD-L1 in human breast tumors and provided a scoring system for the systematic evaluation of CTLA-4 staining.

METHODS

Immunohistochemical staining for PD-L1 and CTLA-4 expression was performed on a tissue microarray of 102 cores, which included normal and neoplastic breast tissues. Neoplastic cores were divided into four groups: Ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC) and invasive tubular carcinoma (ITC). PD-L1 and CTLA-4 expressions were scored based on a system which accounted for the percentage and intensity of positivity and results provided in conjunction with available clinical and demographic data.

RESULTS

Overall, CTLA-4 was over-expressed in 49 of 93 (52.7%) breast tumors. Subcategorically, CTLA-4 was positive in 3 of 8 (37.5%) ductal carcinoma in situ, 40 of 73 (55%) of invasive ductal carcinomas, 4 of 10 (40%) of invasive lobular carcinomas and 2 of 2 (100%) of invasive tubular carcinomas. All 6 normal breast tissues were interpreted as negative for CTLA-4 staining. Only 4.1% of the invasive ductal carcinomas were positive for PD-L1 reactivity and the remaining carcinomas stained negative.

CONCLUSIONS

This study shows a significant overexpression of CTLA-4 in >50% of breast carcinomas with no such overexpression of CTLA-4 in benign breast tissues. PDL-1 staining is seen in only a small number of invasive ductal carcinomas (4.1%). These findings suggest the need for further investigation of anti-CTLA-4 and anti-PD-L1 immunotherapies and their efficacy in the treatment of breast carcinomas with overexpression of these immune modulators. In addition, the proposed scoring system will facilitate a more systematic correlation between tumor reactivity and clinical outcome which can be applied to all intracytoplasmic tumor markers.

Programmed death-ligand 1 (PD-L1) is expressed in a significant number of the uterine cervical carcinomas

BACKGROUND

The programmed death-1/programmed death-ligand-1 (PD-1/PD-L1) immune regulatory axis has emerged as a promising new target for cancer therapeutics, with lasting responses seen in the treatment of metastatic renal and lung carcinomas, as well as melanomas. As tumor surface expression of PD-L1 has been found to correlate with objective responses to anti-PD-L1 immunotherapies, we investigated the expression of PD-L1 in human cervical tumors and provide an adopted scoring system for the systematic evaluation of PD-L1 staining.

METHODS

Immunohistochemical staining for PD-L1 expression was performed on a tissue microarray of 101 normal and neoplastic cervical tissues. Neoplastic cores were divided into three groups: squamous cell carcinoma, adenosquamous carcinoma, and endocervical adenocarcinoma. PD-L1 expression was scored based on an adopted scoring system accounting to percentage and intensity of positivity, and results provided alongside available clinical and demographic data.

RESULTS

Overall, PD-L1 was positive in 32 of 93 (34.4%) cervical carcinomas. Subcategorically, PD-L1 was positive in 28 of 74 (37.8%) squamous cell carcinomas, two of seven (28.6%) adenosquamous carcinomas, and two of 12 (16.7%) endocervical adenocarcinomas. It was negative in six benign cervical tissues.

CONCLUSIONS

This study shows a significant expression of PD-L1 in 34.4% of cervical carcinomas and no expression of PD-L1 in benign cervical tissues. These findings suggest a role for further investigation of anti-PD-L1/PD-1 immunotherapies in the treatment of PD-L1-positive cervical tumors. In addition, our adopted scoring system will facilitate more systematic correlations between tumor reactivity and response to treatment.

Prostate Stem Cell Antigen Expression is Associated With Gleason Score, Seminal Vesicle Invasion and Capsular Invasion in Prostate Cancer

PURPOSE

Few successful therapeutic options exist for men who present with metastatic prostate cancer (CaP) or for the 30% with recurrence. The development and characterization of molecular markers are vital to the development of prognostic and therapeutic modalities in CaP. We investigated the expression and potential clinical usefulness of prostate stem cell antigen (PSCA) in CaP using tissue microarrays.

MATERIALS AND METHODS

Immunohistochemical analysis using a PSCA monoclonal antibody was performed on tissue microarrays constructed from paraffin embedded specimens from 246 patients who underwent radical retropubic prostatectomy. PSCA staining was correlated with established prognostic factors, such as Gleason score, prostate specific antigen (PSA), and seminal vesicle invasion. In addition, recurrence-free survival was analyzed.

RESULTS

A high PSCA intensity of 3 was associated with adverse prognostic features, such as Gleason score 7 and above (p = 0.001), seminal vesicle invasion (p = 0.005) and capsular involvement (p = 0.033). On univariate analysis tumors with a PSCA intensity of 3 carried an increased risk of PSA recurrence (p = 0.031, HR 1.77, 95% CI 1.05 to 2.96). However, after adjusting for these variables a PSCA intensity of 3 was no longer an independent predictor of PSA recurrence.

CONCLUSIONS

We found that high PSCA intensity is significantly associated with adverse prognostic features such as high Gleason score and extra-organ disease. The results of this study suggest that PSCA is a promising tumor marker for the selection of patients at high risk but additional studies are necessary to assess the usefulness of PSCA in patient biopsies.

Novel kidney cancer immunotherapy based on the granulocyte-macrophage colony-stimulating factor and carbonic anhydrase IX fusion gene

PURPOSE

We investigated the ability of the fusion protein granulocyte-macrophage colony-stimulating factor and carbonic anhydrase IX (GMCA-9)(1) to induce an immune response in vitro and in vivo for the development of a GMCA-9-based kidney cancer vaccine.

EXPERIMENTAL DESIGN

Human dendritic cells (DCs) were transduced with a recombinant adenovirus containing the GMCA-9 gene and tested for their capacity to induce CA9-specific cytotoxic T lymphocytes in vitro. Tumor growth was studied in severe compromised immunodeficiency disease (SCID) mice s.c. injected with R11-GMCA-9, a human renal cell carcinoma cell line stably transfected with the GMCA-9 gene. Involvement of natural killer (NK) cells in the antitumor activity of GMCA-9 was determined in SCID mice treated with the NK-blocking agent anti-asialoGM-1.

RESULTS

DC and R11 cells transduced with GMCA-9 produced a GMCA-9 protein that is targeted to the cell membrane and partially processed to granulocyte macrophage colony-stimulating factor- and CA9-like products. Furthermore, GMCA-9 was capable of inducing DC maturation, as well as CA9-specific cytotoxic lymphocytes in vitro. Tumor growth of R11 cells in SCID mice was significantly inhibited after transfection with the GMCA-9 fusion gene (P < 0.01). In mice treated with anti-asialoGM-1, R11-GMCA-9 tumors grew significantly faster than those of control mice (P < 0.05), suggesting an involvement of NK cells.

CONCLUSIONS

Our results suggest that the fusion protein GMCA-9 is capable of generating an immune response both in vitro and in vivo. Additional studies will confirm the utility of ex vivo GMCA-9-transduced DCs as a kidney cancer vaccine.

Induction of G250-targeted and T-cell-mediated antitumor activity against renal cell carcinoma using a chimeric fusion protein consisting of G250 and granulocyte/monocyte-colony stimulating factor

Immunotherapy targeting for the induction of a T-cell-mediated antitumor response in patients with renal cell carcinoma (RCC) appears to hold significant promise. Here we describe a novel RCC vaccine strategy that allows for the concomitant delivery of dual immune activators: G250, a widely expressed RCC associated antigen; and granulocyte/macrophage-colony stimulating factor (GM-CSF), an immunomodulatory factor for antigen-presenting cells. The G250-GM-CSF fusion gene was constructed and expressed in Sf9 cells using a baculovirus expression vector system. The Mr 66,000 fusion protein (FP) was subsequently purified through a 6xHis-Ni2+-NTA affinity column and SP Sepharose/fast protein liquid chromatography. The purified FP retains GM-CSF bioactivity, which is comparable, on a molar basis, to that of recombinant GM-CSF when tested in a GM-CSF-dependent cell line. When combined with interleukin 4 (IL-4; 1000 units/ml), FP (0.34 microg/ml) induces differentiation of monocytes (CD14+) into dendritic cells (DCs) expressing surface markers characteristic for antigen-presenting cells. Up-regulation of mature DCs (CD83+CD19-; 17% versus 6%) with enhanced expression of HLA class I and class II antigens was detected in FP-cultured DCs as compared with DCs cultured with recombinant GM-CSF. Treatment of peripheral blood mononuclear cells (PBMCs) with FP alone (2.7 microg/10(7) cells) augments both T-cell helper 1 (Th1) and Th2 cytokine mRNA expression (IL-2, IL-4, GM-CSF, IFN-gamma, and tumor necrosis factor-alpha). Comparison of various immune manipulation strategies in parallel, bulk PBMCs treated with FP (0.34 microg/ml) plus IL-4 (1000 units/ml) for 1 week and restimulated weekly with FP plus IL-2 (20 IU/ml) induced maximal growth expansion of active T cells expressing the T-cell receptor and specific anti-RCC cytotoxicity, which could be blocked by the addition of anti-HLA class I, anti-CD3, or anti-CD8 antibodies. In one tested patient, an augmented cytotoxicity against lymph node-derived RCC target was determined as compared with that against primary tumor targets, which corresponded to an 8-fold higher G250 mRNA expression in lymph node tumor as compared with primary tumor. The replacement of FP with recombinant GM-CSF as an immunostimulant completely abrogated the selection of RCC-specific killer cells in peripheral blood mononuclear cell cultures. All FP-modulated peripheral blood mononuclear cell cultures with antitumor activity showed an up-regulated CD3+CD4+ cell population. These results suggest that GM-CSF-G250 FP is a potent immunostimulant with the capacity for activating immunomodulatory DCs and inducing a T-helper cell-supported, G250-targeted, and CD8+-mediated antitumor response. These findings may have important implications for the use of GM-CSF-G250 FP as a tumor vaccine for the treatment of patients with advanced kidney cancer.