Prognostic significance of soluble PD-L1 in prostate cancer.

Purpose: The aim of this study was to assess the role of sPD-L1 and sPD-1 as potential biomarkers in prostate cancer (PCa). The association of the values of these soluble proteins were correlated to the clinical data: stage of disease, Gleason score, biochemical recurrence etc. For a comprehensive study, the relationship between sPD-L1 and sPD-1 and circulating immune cells was further investigated. Methods: A total of 88 patients with pT2 and pT3 PCa diagnosis and 41 heathy men were enrolled. Soluble sPD-L1 and sPD-1 levels were measured in plasma by ELISA method. Immunophenotyping was performed by flow cytometry analysis. Results: Our study's findings demonstrate that PCa patients had higher levels of circulating sPD-L1 and sPD-1 comparing to healthy controls (p < 0.001). We found a statistically significant (p < 0.05) relationship between improved progression free survival and lower initial sPD-L1 values. Furthermore, patients with a lower sPD-1/sPD-L1 ratio were associated with a higher probability of disease progression (p < 0.05). Additionally, a significant (p < 0.05) association was discovered between higher Gleason scores and elevated preoperative sPD-L1 levels and between sPD-1 and advanced stage of disease (p < 0.05). A strong correlation (p < 0.05), between immunosuppressive CD4+CD25+FoxP3+ regulatory T cells and baseline sPD-L1 was observed in patients with unfavorable postoperative course of the disease, supporting the idea that these elements influence each other in cancer progression. In addition to the postoperative drop in circulating PD-L1, the inverse relationship (p < 0.05), between the percentage of M-MDSC and sPD-L1 in patients with BCR suggests that M-MDSC is not a source of sPD-L1 in PCa patients. Conclusion: Our findings suggest the potential of sPD-L1 as a promising prognostic marker in prostate cancer.

Atezolizumab Retains Cellular Binding to Programmed Death Ligand 1 Following Aerosolization via Mesh Nebulizer.

BACKGROUND/AIM: Cytotoxic inhalable drugs were shown to be advantageous in treating malignancies of the respiratory tract. However, these drugs have not always presented a safe profile and were reported to induce local adverse events. Protein-based anticancer drugs, such as immune checkpoint and vascular endothelial growth factor inhibitors, do not induce tissue injury, nor do they exhibit vesicant properties upon direct contact with tissues. Protein drugs are susceptible to the heat and stress encountered during droplet generation for delivery by nebulization. The aim of this study was to investigate the capacity of atezolizumab, an antibody to programmed death ligand 1, to bind target cells after nebulization with a vibrating mesh (VM) nebulizer. MATERIALS AND METHODS: We compared Fourier-transformed infrared (FTIR) and Raman spectra of native atezolizumab (60 mg/ml) and its nebulized form following 10-min nebulization in a piezoceramic VM nebulizer. The binding of atezolizumab to DU-145 prostate cancer cells was evaluated using competitive blocking of anti-CD274 staining. RESULTS: Nebulization did not induce Raman or FTIR spectral modification nor did it affect the binding capacity of atezolizumab. Conversely, heat-inactivated atezolizumab lost its cell-binding capacity and did not reduce anti-CD274 immunostaining. Native and nebulized atezolizumab displayed identical spectra, whereas the FTIR spectra of the heat-inactivated drug was significantly altered. CONCLUSION: VM nebulization does not obliterate the functionality of the drug atezolizumab. The integrity of a nebulized form can be rapidly assessed by FTIR and Raman spectrometry.

Thymus Subset Alterations Accompanying Concomitant Tumor Immunity Mimics Phenotypic Patterns of Cytotoxic Drug Doxorubicin.

BACKGROUND/AIM: Concomitant immunity (CIM) is a phenomenon that elicits an antitumor response not sufficient enough to destroy the primary tumor but prevents a secondary implant from growing and spreading. This study aimed to develop a method of identification of serum tumoricidal factors released into circulation during CIM and to compare the CIM-related effect to the effect elicited by the cytotoxic drug doxorubicin. MATERIALS AND METHODS: SL2 tumor-bearing mice were studied at three time points - day 4, day 7, and day 11 following i.p. 5×105 cell implantation. Hematological effects and thymocyte immunophenotyping (CD4/CD8) data were compared to the effects induced by intravenous 10 mg/kg doxorubicin (DOX) administration to intact DBA 2 mice. The level of plasma colony stimulating factor-granulocyte macrophage (CSF-GM) was evaluated by ELISA. RESULTS: Identical thymus histopathology and an extent of double-positive CD4+CD8+ subset depletion was found in day 11 tumor-bearing mice (TBM-11) and in DOX-administered animals. TBM-11 exhibited a leukemoid reaction with an increase in monocyte and granulocyte counts. Conversely, DOX administration was followed by severe leukocytopenia at the 72-h time point. No increase in CSF-GM was observed in mice with or without a leukemoid reaction. CONCLUSION: The complexity of CIM can be examined by tracking alterations in the most fragile cortical CD8+CD4+ double positive population. Thymocyte apoptosis induced by DOX and TBM-11 might be associated with different mechanisms. TBM-11 did not exhibit severe myelotoxicity as DOX did. CIM-related serum factors can be assessed and screened via thymocyte subset analysis.

Intratumoral Accumulation and Clonal Expansion May Not Be Decisive for Rejection of Allogeneic Tumors by CD8+ T-Lymphocytes.

BACKGROUND: The aim of this study was to analyze the spatial distribution and proliferation of adoptively transferred CD8+ T-lymphocytes sensitized against allogeneic tumors. MATERIALS AND METHODS: Transgenic ß-actin-luc mice that express luciferase were sensitized against allogeneic SL2 lymphoma. CD8+ T-lymphocytes from these mice were transferred to lymphocyte-deficient, recombination activating gene-deficient (Rag-/-) mice bearing SL2 tumors and were tracked using bioluminescence imaging. RESULTS: Two out of six Rag-/- mice rejected their tumors. There were no apparent differences in spatial distribution and proliferative intensity of adoptively-transferred CD8+ T-lymphocytes between the two Rag-/- mice that rejected allogeneic SL2 tumors and the four Rag-/- mice that did not. CONCLUSION: The pattern of distribution in the mouse body and proliferative intensity of CD8+ T-lymphocytes do not seem to be decisive factors influencing allogeneic tumor rejection.

Bioluminescence Imaging of Adoptively Transferred Lymphocytes During Allogeneic Tumor Rejection.

AIM: The aim of the present study was to analyze the survival, spatial distribution and proliferation of adoptively transferred lymphocytes in allogeneic tumor rejection. MATERIALS AND METHODS: Transgenic ß-actin-luc mice that express luciferase were sensitized against SL2 tumors and were used as lymphocyte donors to study the anti-tumor effect in SL2 tumor-bearing lymphocyte-deficient RAG(-/-) mice. Whole-body bioluminescence images of recipient mice were obtained to track the adoptively transferred lymphocytes. Proliferation of lymphocytes was estimated by quantification of photon emission. RESULTS: T lymphocytes sensitized against allogeneic SL2 tumors cured the majority of SL2 tumor-bearing RAG(-/-) mice. Bioluminescence imaging showed that transferred T lymphocytes survived in the spleen and lymph nodes. Tumor rejection was associated with lymphocyte proliferation and migration to the tumor site. CONCLUSION: Sensitized T lymphocytes from transgenic ß-actin-luc mice reject allogeneic SL2 tumors in RAG(-/-) mice and can be tracked in vivo using bioluminescence imaging.

Expanded effector memory T-lymphocytes in DBA/2 mice do not inhibit the growth of SL2 tumours.

BACKGROUND: The aim of this study was to analyse changes in levels of memory T-lymphocytes during growth of SL2 tumours in DBA/2 mice and to evaluate whether these lymphocytes may have an inhibitory effect on tumour growth. MATERIALS AND METHODS: Percentages of naïve (CD8+CD44lowCD62L+), central memory (CD8+CD44high CD62L+) and effector memory (CD8+CD44highCD62L-) lymphocytes in the CD8+ subset in peripheral blood, spleen and lymph nodes of tumour-bearing and control mice were analysed by flow cytometry. RESULTS: The percentage of effector memory lymphocytes in the CD8+ subset increased during growth of tumours, whereas that of naïve CD8+ lymphocytes decreased. No correlation between the levels of effector memory lymphocytes in peripheral blood and the mass of tumours was found. CONCLUSION: SL2 tumours induce expansion of effector memory lymphocytes in DBA/2 mice. However, expanded effector memory lymphocytes do not inhibit the growth of tumours.