Biomarker screen for efficacy of oncolytic virotherapy in patient-derived pancreatic cancer cultures.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a tumour entity with unmet medical need. To assess the therapeutic potential of oncolytic virotherapy (OVT) against PDAC, different oncolytic viruses (OVs) are currently investigated in clinical trials. However, systematic comparisons of these different OVs in terms of efficacy against PDAC and biomarkers predicting therapeutic response are lacking. METHODS: We screened fourteen patient-derived PDAC cultures which reflect the intra- and intertumoural heterogeneity of PDAC for their sensitivity to five clinically relevant OVs, namely serotype 5 adenovirus Ad5-hTERT, herpes virus T-VEC, measles vaccine strain MV-NIS, reovirus jin-3, and protoparvovirus H-1PV. Live cell analysis, quantification of viral genome/gene expression, cell viability as well as cytotoxicity assays and titration of viral progeny were conducted. Transcriptome profiling was employed to identify potential predictive biomarkers for response to OV treatment. FINDINGS: Patient-derived PDAC cultures showed individual response patterns to OV treatment. Twelve of fourteen cultures were responsive to at least one OV, with no single OV proving superior or inferior across all cultures. Known host factors for distinct viruses were retrieved as potential biomarkers. Compared to the classical molecular subtype, the quasi-mesenchymal or basal-like subtype of PDAC was found to be more sensitive to H-1PV, jin-3, and T-VEC. Generally, expression of viral entry receptors did not correlate with sensitivity to OV treatment, with one exception: Expression of Galectin-1 (LGALS1), a factor involved in H-1PV entry, positively correlated with H-1PV induced cell killing. Rather, cellular pathways controlling immunological, metabolic and proliferative signaling appeared to determine outcome. For instance, high baseline expression of interferon-stimulated genes (ISGs) correlated with relative resistance to oncolytic measles virus, whereas low cyclic GMP-AMP synthase (cGAS) expression was associated with exceptional response. Combination treatment of MV-NIS with a cGAS inhibitor improved tumour cell killing in several PDAC cultures and cells overexpressing cGAS were found to be less sensitive to MV oncolysis. INTERPRETATION: Considering the heterogeneity of PDAC and the complexity of biological therapies such as OVs, no single biomarker can explain the spectrum of response patterns. For selection of a particular OV, PDAC molecular subtype, ISG expression as well as activation of distinct signaling and metabolic pathways should be considered. Combination therapies can overcome resistance in specific constellations. Overall, oncolytic virotherapy is a viable treatment option for PDAC, which warrants further development. This study highlights the need for personalised treatment in OVT. By providing all primary data, this study provides a rich source and guidance for ongoing developments. FUNDING: German National Science Foundation (Deutsche Forschungsgemeinschaft, DFG), German Cancer Aid (Deutsche Krebshilfe), German National Academic Scholarship Foundation (Studienstiftung des deutschen Volkes), Survival with Pancreatic Cancer Foundation.

Partial-Volume Irradiation of Murine Tumors.

Radiotherapy is a widely used approach for cancer treatment. However, delivering a single high dose of radiation to bulky tumors can be challenging due to the toxicities induced in the surrounding healthy tissue. To overcome this issue, a nonuniform high dose can be delivered using partial-volume tumor irradiation or spatially fractionated radiotherapy (SFRT). Moreover, SFRT has the potential to induce a stronger antitumor immune response compared to traditional radiotherapy due to the preservation of immune cells in the unirradiated tumor regions. There are several SFRT approaches, including GRID therapy, three-dimensional GRID therapy (LATTICE), microbeam radiation therapy (MRT), and Stereotactic Body Radiation Therapy for PArtial Tumor irradiation targeting exclusively the HYpoxic segment (SBRT-PATHY). The following protocol describes partial-volume tumor irradiation, a technique that enables dose delivery to only a part of the tumor in mice using an X-ray generator and collimators of different dimensions that limit the size of the irradiation field.

What We Learned about the Feasibility of Gene Electrotransfer for Vaccination on a Model of COVID-19 Vaccine.

DNA vaccination is one of the emerging approaches for a wide range of applications, including prophylactic vaccination against infectious diseases and therapeutic vaccination against cancer. The aim of this study was to evaluate the feasibility of our previously optimized protocols for gene electrotransfer (GET)-mediated delivery of plasmid DNA into skin and muscle tissues on a model of COVID-19 vaccine. Plasmids encoding the SARS-CoV-2 proteins spike (S) and nucleocapsid (N) were used as the antigen source, and a plasmid encoding interleukin 12 (IL-12) was used as an adjuvant. Vaccination was performed in the skin or muscle tissue of C57BL/6J mice on days 0 and 14 (boost). Two weeks after the boost, blood, spleen, and transfected tissues were collected to determine the expression of S, N, IL-12, serum interferon-γ, the induction of antigen-specific IgG antibodies, and cytotoxic T-cells. In accordance with prior in vitro experiments that indicated problems with proper expression of the S protein, vaccination with S did not induce S-specific antibodies, whereas significant induction of N-specific antibodies was detected after vaccination with N. Intramuscular vaccination outperformed skin vaccination and resulted in significant induction of humoral and cell-mediated immunity. Moreover, both boost and adjuvant were found to be redundant for the induction of an immune response. Overall, the study confirmed the feasibility of the GET for DNA vaccination and provided valuable insights into this approach.

Association of Circulating Tumor Cells, Megakaryocytes and a High Immune-Inflammatory Environment in Metastatic Breast Cancer.

Liquid biopsy is becoming an important source of new biomarkers during the treatment of metastatic cancer patients. Using size-based microfluid technology, we isolated circulating tumor cells (CTCs) from metastatic breast cancer patients to evaluate their presence and cluster formation, as well as the presence of megakaryocytes and immune-inflammatory blood cells, and to correlate their presence with clinicopathological data and overall survival (OS). In total, 59 patients (median age 60.4 years) were included in the study: 62.7% luminal A/B-like, 20.3% HER2-positive, and 17% triple-negative. Our results showed that at least one CTC was present in 79.7% and ≥5 CTCs in 35.2% of the patients. CTC clusters were present in patients with ≥5 CTCs only (in 19.2% of them), and megakaryocytes were present in 52% of all patients. The presence of CTC clusters and megakaryocytes was positively associated with the CTC count. Patients with low pan-inflammatory value (PIV), low systemic immune-inflammatory index (SII), and low relative change from baseline (ΔPIV%, ΔSII%) were associated with significantly higher OS than their counterparts. ΔPIV%, the presence of infection in the last month, and a long duration of metastatic disease were identified as independent prognostic factors for OS. The interplay of CTCs, CTC clusters, megakaryocytes, and PIV needs to be further explored.

HPV-positive murine oral squamous cell carcinoma: development and characterization of a new mouse tumor model for immunological studies.

BACKGROUND: Infection with high-risk human papillomavirus (HPV) strains is one of the risk factors for the development of oral squamous cell carcinoma (OSCC). Some patients with HPV-positive OSCC have a better prognosis and respond better to various treatment modalities, including radiotherapy or immunotherapy. However, since HPV can only infect human cells, there are only a few immunocompetent mouse models available that enable immunological studies. Therefore, the aim of our study was to develop a transplantable immunocompetent mouse model of HPV-positive OSCC and characterize it in vitro and in vivo. METHODS: Two monoclonal HPV-positive OSCC mouse cell lines were established by inducing the expression of HPV-16 oncogenes E6 and E7 in the MOC1 OSCC cell line using retroviral transduction. After confirming stable expression of HPV-16 E6 and E7 with quantitative real-time PCR and immunofluorescence staining, the cell lines were further characterized in vitro using proliferation assay, wound healing assay, clonogenic assay and RNA sequencing. In addition, tumor models were characterized in vivo in C57Bl/6NCrl mice in terms of their histological properties, tumor growth kinetics, and radiosensitivity. Furthermore, immunofluorescence staining of blood vessels, hypoxic areas, proliferating cells and immune cells was performed to characterize the tumor microenvironment of all three tumor models. RESULTS: Characterization of the resulting MOC1-HPV cell lines and tumor models confirmed stable expression of HPV-16 oncogenes and differences in cell morphology, in vitro migration capacity, and tumor microenvironment characteristics. Although the cell lines did not differ in their intrinsic radiosensitivity, one of the HPV-positive tumor models, MOC1-HPV K1, showed a significantly longer growth delay after irradiation with a single dose of 15 Gy compared to parental MOC1 tumors. Consistent with this, MOC1-HPV K1 tumors had a lower percentage of hypoxic tumor area and a higher percentage of proliferating cells. Characteristics of the newly developed HPV-positive OSCC tumor models correlate with the transcriptomic profile of MOC1-HPV cell lines. CONCLUSIONS: In conclusion, we developed and characterized a novel immunocompetent mouse model of HPV-positive OSCC that exhibits increased radiosensitivity and enables studies of immune-based treatment approaches in HPV-positive OSCC.

Morphological features of breast cancer circulating tumor cells in blood after physical and biological type of isolation.

BACKGROUND: Circulating tumor cells (CTCs) have become an important biomarker in breast cancer. Different isolation tech-niques based on their biological or physical features were established. Currently, the most widely used methods for visualization after their separation are based on immunofluorescent staining, which does not provide the information on the morphology. MATERIALS AND METHODS: The aim of this study was to evaluate how two different separation techniques affect cell morphology and to analyse cell morphology with techniques used in routine cytopathological laboratory. A direct side-by-side comparison of physical (Parsortix®) and biological (MACS®) separation technique was performed. RESULTS: In the preclinical setting, both isolation techniques retained the viability and antigenic characteristics of MCF7 breast cancer cells. Some signs of degeneration such as cell swelling, cytoplasmic blebs, villous projections and vacuolization were observed. In metastatic breast cancer patient cohort, morphological features of isolated CTCs were dependent on the separation technique. After physical separation, CTCs with preserved cell morphology were detected. After biological separation the majority of the isolated CTCs were so degenerated that their identity was difficult to confirm. CONCLUSIONS: Taken together, physical separation is a suitable technique for detection of CTCs with preserved cell morphology for the use in a routine cytopathological laboratory.

Recent developments in immunotherapy of cancers caused by human papillomaviruses.

A subset of oncogenic human papillomaviruses (HPVs) is the main cause of genital cancers, most importantly cervical cancer and an increasing number of head and neck cancers. Despite the availability of prophylactic vaccines against the most prevalent oncogenic HPV types, HPV-induced malignancies are still a major health and economic burden. Besides conventional treatment with surgery, chemotherapy and radiation, immunotherapy is emerging as an efficient adjuvant option. Here, we review relevant studies and ongoing clinical trials using immune checkpoint inhibitors, therapeutic vaccines, gene editing approaches and adoptive T cell therapies, with special focus on engineered TCR T cells, which are showing encouraging results and could lead to significant improvement in the treatment of HPV+-infected cancer patients.