CAR T cells redirected against tumor-specific antigen glycoforms: can low-sugar antigens guarantee a sweet success? / 医学前沿

Immune-based therapies have experienced a pronounced breakthrough in the past decades as they acquired multiple US Food and Drug Administration (FDA) approvals for various indications. To date, six chimeric antigen receptor T cell (CAR-T) therapies have been permitted for the treatment of certain patients with relapsed/refractory hematologic malignancies. However, several clinical trials of solid tumor CAR-T therapies were prematurely terminated, or they reported life-threatening treatment-related damages to healthy tissues. The simultaneous expression of target antigens by healthy organs and tumor cells is partly responsible for such toxicities. Alongside targeting tumor-specific antigens, targeting the aberrantly glycosylated glycoforms of tumor-associated antigens can also minimize the off-tumor effects of CAR-T therapies. Tn, T, and sialyl-Tn antigens have been reported to be involved in tumor progression and metastasis, and their expression results from the dysregulation of a series of glycosyltransferases and the endoplasmic reticulum protein chaperone, Cosmc. Moreover, these glycoforms have been associated with various types of cancers, including prostate, breast, colon, gastric, and lung cancers. Here, we discuss how underglycosylated antigens emerge and then detail the latest advances in the development of CAR-T-based immunotherapies that target some of such antigens.

Caracterização funcional da interação entre as proteínas CTSP-1 e CTCF / Functional characterization of the interaction between the proteins CTSP-1 and CTCF

Os antígenos cancer-testis (CT) são proteínas imunogênicas expressas em tecido gametogênico e em diferentes tipos de tumor, sendo considerados candidatos promissores para a imunoterapia do câncer. Entretanto, pouco se sabe sobre a função desses antígenos na tumorigênese. Em 2006, identificamos CTSP-1 como um novo antígeno CT, frequentemente expresso em vários tumores. Nesse trabalho, investigamos a função de CTSP-1 por meio da identificação de proteínas expressas em tumores de próstata e que são capazes de interagir fisicamente com esse antígeno. Demonstramos que CTSP-1 interage com a proteína CTCF em ensaios de duplo-híbrido em leveduras, pulldown e de co-localização e, em seguida, analisamos o impacto da superexpressão de CTSP-1 no controle da expressão de genes CT mediada por CTCF e na progressão do ciclo celular. Utilizando o CT NY-ESO-1 como modelo, demonstramos que a superexpressão de CTSP-1 não altera os níveis endógenos de NY-ESO-1 na linhagem celular tumoral H1299. Por outro lado, observamos que a superexpressão de CTSP-1 48h após as transfecções em H1299 induz um bloqueio do ciclo em G0/G1, reduzindo a capacidade clonogênica dessas células por um mecanismo dependente dos níveis de expressão de CTSP-1. Resultados semelhantes não foram observados em ensaios com clones superexpressando CTSP-1 estavelmente, o que sugere que eles tenham se originado de células que conseguiram escapar do bloqueio em G0/G1. Resultados preliminares sugerem que a redução da capacidade clonogênica das células H1299 que superexpressam CTSP-1 48h após as tansfecções não está associada à ocorrência de morte por apoptose.

Cancer-testis (CT) antigens are immunogenic proteins expressed in gametogenic tissues and in different histological types of tumors, being considered promising candidates for cancer immunotherapy. However, little is known about their role in tumorigenesis. In 2006, we identified CTSP-1 as a novel CT antigen, frequently expressed in different types of tumors. In this work, we investigated the functional role of CTSP-1 through the identification of proteins expressed in prostate tumors and that physically interact with this tumor antigen. We demonstrate that CTSP-1 interacts with the CTCF protein using the yeast two-hybrid system, pulldown and co-localization assays and have further analyzed the impact of CTSP-1 overexpression on the expression of CT genes mediated by CTCF and on the cell cycle progression. Using the CT antigen NY-ESO-1 as a model, we showed that the CTSP-1 overexpression does not alter the endogenous levels of NY-ESO-1 in the tumor cell line H1299. On the other hand, we observed that the overexpression of CTSP-1 in H1299 cells 48h after the transfections induces a cell cycle arrest in G0/G1 and reduces the clonogenic capacity of these cells by a mechanism dependent on the CTSP-1 expression levels. Similar results were not observed for cell clones stably overexpressing CTSP-1, suggesting that these clones have arisen from cells that managed to escape cell cycle arrest in G0/G1. Preliminary results suggest that the reduced clonogenic capacity of H1299 cells expressing CTSP-1 and analyzed 48h after the transfections is not associated with cell death by apoptosis.

Primary lymphoma of the ovary.

Involvement of the ovary by malignant lymphoma is a well-known late manifestation of disseminated nodal disease. Primary ovarian lymphoma is rare. We report a case of primary ovarian non-Hodgkin's lymphoma with bilateral involvement which was managed by surgery and chemotherapy. A 29-year-old woman was admitted with signs and symptoms suggestive of an ovarian cancer. Computed tomography revealed an abdominal tumor measuring 20 cm in diameter, without enlarged lymph nodes. The diagnosis of malignant lymphoma was established after bilateral adnexectomy and histological study of the excised tissue. The tumor was classified as a diffuse large B-cell lymphoma. The patient has been advised 8 cycles of standard CHOP regimen and is presently on treatment. She has now been without disease for 7 months after the surgery. According to previous reports the treatment principles and prognosis of primary ovarian lymphoma is the same as that of other nodal lymphomas.

The centrosomal localization of KM-HN-1 (MGC33607) depends on the leucine zipper motif and the C-terminal coiled-coil domain

KM-HN-1 is a C-terminal coiled-coil domain containing protein previously referred to as image clone MGC33607. This protein has been previously identified as a cancer/testis antigen and reported as nuclear and chromatin localizing protein. We raised polyclonal antisera with the GST fusion protein and identified them as a 105 kDa protein. Motif analysis showed that this protein harbors the leucine zipper motif in internal 1/3 region and the coiled-coil domain in the C-terminal region. Using the full length and various deletion mutants, we determined the motif that governs the subcellular localization of KM-HN-1. Immunofluorescence staining of the endogenous KM-HN-1 and various kinds of GFP-tagged KM-HN-1 revealed that KM-HN-1 localizes to the centrosomes as well as nucleus. The centrosomal localization-determining region of this protein is C-terminal coiled-coil domain in which the leucine zipper motif and the nuclear export signal (NES) harbor.

Dendritic cell, the immunotherapeutic cell for cancer.

Dendritic cells play an important role in the development of effective cancer vaccines. These cells have the potential to present tumour-specific antigens and thereby induce an immune response. Various studies involving clinical trials have investigated the efficacy of administering antigen-loaded dendritic cells for cancer therapy. In order to design such experiments it is important to consider specific antigens, which initiate either a CD4+ or CD8+ response or both. The present review discusses the unique properties of dendritic cells as an immunotherapeutic cell for cancer.

Suppression of Ehrlich ascites tumor growth by immunization with ganglioside GT1b of its origin, its IgM antibody or anti-idiotype of the anti-GT1b IgM.

Ehrlich tumor expresses the ganglioside GT1b. The plasma of mice with Ehrlich ascites tumor burden also contains GT1b. The structural identity of plasma GT1b was ascertained by a series of enzymatic degradation and mass spectral analysis. Mice were vaccinated with purified plasma GT1b admixed with Freund's adjuvant (FA). Sixty nine percent suppression of Ehrlich ascites tumor growth was observed in vaccinated mice. The suppression was dose-dependent. It is hypothesized that the tumor growth-suppression is a result of immune response to GT1b Humoral immune response to GT1b was demonstrated by passive hemagglutination assay of the sera of vaccinated mice. To test the hypothesis, the mice were administered with rabbit polyclonal anti-GT1b IgM antibody in varying doses and challenged with Ehrlich tumor. A significant reduction in tumor growth (65%) was observed in mice administered with anti-GT1b IgM antibody. Again, the suppression was dose-dependent. To verify further, another batch of mice was immunized with anti-idiotypic antibodies to rabbit anti-GT1b IgM raised in rat. The polyclonal anti-idiotype antibody is expected to carry the structural image of GT1b. In a dose-dependent manner, a maximum of 82% suppression of tumor growth was observed in mice immunized with the anti-idiotype antibody. This observation further strengthened the hypothesis that ganglioside mediated suppression of tumor growth may be a result of immunogenicity of the target ganglioside. This was also supported by positive reaction of the sera of anti-idiotype vaccinated mice with both anti-idiotype antibody and ganglioside GT1b in passive hemagglutination assay. The results favour the therapeutic potential of immunogenic tumor-associated gangliosides.