Feasibility study of using high-throughput drug sensitivity testing to target recurrent glioblastoma stem cells for individualized treatment

Intraoperative radiotherapy in recurrent IDH-wildtype glioblastoma with gross total resection: A single-center retrospective study

BACKGROUND

Isocitrate dehydrogenase-wildtype (IDHwt) glioblastoma (GBM) is one of the most aggressive primary brain tumors. The recurrence of GBM is almost inevitable. As an adjuvant option to surgery, intraoperative radiotherapy (IORT) is gaining increasing attention in the treatment of glioma. This study is aimed to evaluate the therapeutic efficacy of IORT on recurrent IDHwt GBM.

METHODS

In total, 34 recurrent IDHwt GBM patients who received a second surgery were included in the analysis (17 in the surgery group and 17 in the surgery + IORT group).

RESULTS

The progression-free survival and overall survival after the second surgery were defined as PFS2 and OS2, respectively. The median PFS2 was 7.3 months (95% CI: 6.3-10.5) and 10.6 months (95% CI: 9.3-14.6) for those patients who received surgery and surgery + IORT, respectively. Patients in the surgery + IORT group also had a longer OS2 (12.8 months, 95% CI: 11.4-17.2) than those in the surgery group (9.3 months, 95% CI: 8.9-12.9). The Kaplan-Meier survival curves, analyzed by log-rank test, revealed a statistically significant difference in PFS2 and OS2 between both groups, suggesting that IORT plays an active role in the observed benefits for PFS2 and OS2. The effects of IORT on PFS2 and OS2 were further confirmed by multivariate Cox hazards regression analysis. Two patients in the surgery group developed distant glioma metastases, and no radiation-related complications were observed in the IORT group.

CONCLUSIONS

This study suggests that low-dose IORT may improve the prognosis of recurrent IDHwt GBM patients. Future prospective large-scale studies are needed to validate the efficacy and safety of IORT.

Functional and Molecular Heterogeneity in Glioma Stem Cells Derived from Multiregional Sampling

Glioblastoma (GBM) is an aggressive and highly heterogeneous primary brain tumor. Glioma stem cells represent a subpopulation of tumor cells with stem cell traits that are presumed to be the cause of tumor relapse. There exists complex tumor heterogeneity in drug sensitivity patterns between glioma stem cell (GSC) cultures derived from different patients. Here, we describe that heterogeneity also exists between GSC cultures derived from multiple biopsies within a single tumor. From biopsies harvested within spatially distinct regions representing the entire tumor mass, we established seven GSC cultures and compared their stem cell properties, mutations, gene expression profiles, and drug sensitivity patterns against 115 different anticancer drugs. The results were compared to 14 GSC cultures derived from other patients. Between the multiregional-derived GSC cultures, we observed only minor differences in their phenotype, proliferative capacity, and global gene expression. Further, they displayed intratumoral heterogeneity in mutational profiles and sensitivity patterns to anticancer drugs. This heterogeneity, however, did not exceed the extensive heterogeneity found between GSC cultures derived from other GBM patients. Our results suggest that the use of GSC cultures from one single focal biopsy may underestimate the overall complexity of the GSC population and display the importance of including GSC cultures reflecting the entire tumor mass in drug screening strategies.

Breeze 2.0: an interactive web-tool for visual analysis and comparison of drug response data

Functional precision medicine (fPM) offers an exciting, simplified approach to finding the right applications for existing molecules and enhancing therapeutic potential. Integrative and robust tools ensuring high accuracy and reliability of the results are critical. In response to this need, we previously developed Breeze, a drug screening data analysis pipeline, designed to facilitate quality control, dose-response curve fitting, and data visualization in a user-friendly manner. Here, we describe the latest version of Breeze (release 2.0), which implements an array of advanced data exploration capabilities, providing users with comprehensive post-analysis and interactive visualization options that are essential for minimizing false positive/negative outcomes and ensuring accurate interpretation of drug sensitivity and resistance data. The Breeze 2.0 web-tool also enables integrative analysis and cross-comparison of user-uploaded data with publicly available drug response datasets. The updated version incorporates new drug quantification metrics, supports analysis of both multi-dose and single-dose drug screening data and introduces a redesigned, intuitive user interface. With these enhancements, Breeze 2.0 is anticipated to substantially broaden its potential applications in diverse domains of fPM.

Single-cell molecular profiling using ex vivo functional readouts fuels precision oncology in glioblastoma

BACKGROUND

Functional profiling of freshly isolated glioblastoma (GBM) cells is being evaluated as a next-generation method for precision oncology. While promising, its success largely depends on the method to evaluate treatment activity which requires sufficient resolution and specificity.

METHODS

Here, we describe the 'precision oncology by single-cell profiling using ex vivo readouts of functionality' (PROSPERO) assay to evaluate the intrinsic susceptibility of high-grade brain tumor cells to respond to therapy. Different from other assays, PROSPERO extends beyond life/death screening by rapidly evaluating acute molecular drug responses at single-cell resolution.

RESULTS

The PROSPERO assay was developed by correlating short-term single-cell molecular signatures using mass cytometry by time-of-flight (CyTOF) to long-term cytotoxicity readouts in representative patient-derived glioblastoma cell cultures (n = 14) that were exposed to radiotherapy and the small-molecule p53/MDM2 inhibitor AMG232. The predictive model was subsequently projected to evaluate drug activity in freshly resected GBM samples from patients (n = 34). Here, PROSPERO revealed an overall limited capacity of tumor cells to respond to therapy, as reflected by the inability to induce key molecular markers upon ex vivo treatment exposure, while retaining proliferative capacity, insights that were validated in patient-derived xenograft (PDX) models. This approach also allowed the investigation of cellular plasticity, which in PDCLs highlighted therapy-induced proneural-to-mesenchymal (PMT) transitions, while in patients' samples this was more heterogeneous.

CONCLUSION

PROSPERO provides a precise way to evaluate therapy efficacy by measuring molecular drug responses using specific biomarker changes in freshly resected brain tumor samples, in addition to providing key functional insights in cellular behavior, which may ultimately complement standard, clinical biomarker evaluations.

Glioblastoma and the search for non-hypothesis driven combination therapeutics in academia

Glioblastoma (GBM) remains a cancer of high unmet clinical need. Current standard of care for GBM, consisting of maximal surgical resection, followed by ionisation radiation (IR) plus concomitant and adjuvant temozolomide (TMZ), provides less than 15-month survival benefit. Efforts by conventional drug discovery to improve overall survival have failed to overcome challenges presented by inherent tumor heterogeneity, therapeutic resistance attributed to GBM stem cells, and tumor niches supporting self-renewal. In this review we describe the steps academic researchers are taking to address these limitations in high throughput screening programs to identify novel GBM combinatorial targets. We detail how they are implementing more physiologically relevant phenotypic assays which better recapitulate key areas of disease biology coupled with more focussed libraries of small compounds, such as drug repurposing, target discovery, pharmacologically active and novel, more comprehensive anti-cancer target-annotated compound libraries. Herein, we discuss the rationale for current GBM combination trials and the need for more systematic and transparent strategies for identification, validation and prioritisation of combinations that lead to clinical trials. Finally, we make specific recommendations to the preclinical, small compound screening paradigm that could increase the likelihood of identifying tractable, combinatorial, small molecule inhibitors and better drug targets specific to GBM.

Functional temozolomide sensitivity testing of patient-specific glioblastoma stem cell cultures is predictive of clinical outcome

Serum-free culturing of patient-derived glioblastoma biopsies enrich for glioblastoma stem cells (GSCs) and is recognized as a disease-relevant model system in glioblastoma (GBM). We hypothesized that the temozolomide (TMZ) drug sensitivity of patient-derived GSC cultures correlates to clinical sensitivity patterns and has clinical predictive value in a cohort of GBM patients. To this aim, we established 51 individual GSC cultures from surgical biopsies from both treatment-naïve primary and pretreated recurrent GBM patients. The cultures were evaluated for sensitivity to TMZ over a dosing range achievable in normal clinical practice. Drug efficacy was quantified by the drug sensitivity score. MGMT-methylation status was investigated by pyrosequencing. Correlative, contingency, and survival analyses were performed for associations between experimental and clinical data. We found a heterogeneous response to temozolomide in the GSC culture cohort. There were significant differences in the sensitivity to TMZ between the newly diagnosed and the TMZ-treated recurrent disease (p <0.01). There was a moderate correlation between MGMT-status and sensitivity to TMZ (r=0.459, p=0.0009). The relationship between MGMT status and TMZ efficacy was statistically significant on multivariate analyses (p=0.0051). We found a predictive value of TMZ sensitivity in individual GSC cultures to patient survival (p=0.0089). We conclude that GSC-enriched cultures hold clinical and translational relevance by their ability to reflect the clinical heterogeneity in TMZ-sensitivity, substantiate the association between TMZ-sensitivity and MGMT-promotor methylation status and appear to have a stronger predictive value than MGMT-promotor methylation on clinical responses to TMZ.

Functional Precision Oncology: The Next Frontier to Improve Glioblastoma Outcome?

Glioblastoma remains the most malignant and intrinsically resistant brain tumour in adults. Despite intensive research over the past few decades, through which numerous potentially druggable targets have been identified, virtually all clinical trials of the past 20 years have failed to improve the outcome for the vast majority of GBM patients. The observation that small subgroups of patients displayed a therapeutic response across several unsuccessful clinical trials suggests that the GBM patient population probably consists of multiple subgroups that probably all require a distinct therapeutic approach. Due to extensive inter- and intratumoral heterogeneity, assigning the right therapy to each patient remains a major challenge. Classically, bulk genetic profiling would be used to identify suitable therapies, although the success of this approach remains limited due to tumor heterogeneity and the absence of direct relationships between mutations and therapy responses in GBM. An attractive novel strategy aims at implementing methods for functional precision oncology, which refers to the evaluation of treatment efficacies and vulnerabilities of (ex vivo) living tumor cells in a highly personalized way. Such approaches are currently being implemented for other cancer types by providing rapid, translatable information to guide patient-tailored therapeutic selections. In this review, we discuss the current state of the art of transforming technologies, tools and challenges for functional precision oncology and how these could improve therapy selection for GBM patients.

Drug Repurposing, a Fast-Track Approach to Develop Effective Treatments for Glioblastoma

Glioblastoma (GBM) remains one of the most difficult tumors to treat. The mean overall survival rate of 15 months and the 5-year survival rate of 5% have not significantly changed for almost 2 decades. Despite progress in understanding the pathophysiology of the disease, no new effective treatments to combine with radiation therapy after surgical tumor debulking have become available since the introduction of temozolomide in 1999. One of the main reasons for this is the scarcity of compounds that cross the blood-brain barrier (BBB) and reach the brain tumor tissue in therapeutically effective concentrations. In this review, we focus on the role of the BBB and its importance in developing brain tumor treatments. Moreover, we discuss drug repurposing, a drug discovery approach to identify potential effective candidates with optimal pharmacokinetic profiles for central nervous system (CNS) penetration and that allows rapid implementation in clinical trials. Additionally, we provide an overview of repurposed candidate drug currently being investigated in GBM at the preclinical and clinical levels. Finally, we highlight the importance of phase 0 trials to confirm tumor drug exposure and we discuss emerging drug delivery technologies as an alternative route to maximize therapeutic efficacy of repurposed candidate drug.

Application of High-Efficiency Cell Expansion and High-Throughput Drug Sensitivity Screening for Leukemia Treatment

This study is to assess the clinical value of in vitro primary cell high-efficiency expansion and high-throughput drug sensitivity screening (HEHDS) system in leukemia, and we evaluated a cohort of 121 patients with acute myeloid leukemia (AML) and 27 patients with acute lymphoblastic leukemia (ALL) using HEHDS. Bone marrow aspirates were collected from patients with leukemia. Purified leukemic cancer cells were obtained, cultured, and screened with a panel of 247 FDA-approved compounds by HEHDS technology. Ninety-six patients received HEHDS-guided therapy while 52 patients who were subjected to physician directed therapy served as controls. ALL patients who received treatment guided by HEHDS showed higher rate of complete remission (CR) than that of patients in the non-HEHDS group (90.91% vs. 56.25%). Similarly, AML patients received HEHDS-guided therapy were found to have greater CR rate, when compared with patients who received physician-directed therapy (45.88% vs. 25%). There was a significantly higher rate of CR in HEHDS-guided therapy group compared to the non-HEHDS group. The application of HEHDS could be beneficial for leukemia treatment.

The Signaling Pathways Controlling the Efficacy of Glioblastoma Therapy

The resistance of glioblastoma to existing therapies puts limits on quality-of-life improvements and patient survival with a glioblastoma diagnosis. The development of new effective glioblastoma therapies is based on knowledge about the mechanisms governing tumor resistance to therapeutic agents. Virotherapy is one of the most actively developing approaches to the treatment of malignant neoplasms: glioblastoma in particular. Previously, we demonstrated that the recombinant vaccinia virus VV-GMCSF-Lact exhibits in vitro cytotoxic activity and in vivo antitumor efficacy against human glioblastoma. However, the studied glioblastoma cell cultures had different sensitivities to the oncotoxic effect of the virus. In this study, we investigated cancer stem cell (CSC) surface markers in glioblastoma cells with different sensitivities to VV-GMCSFLact using flow cytometry and we assessed the levels of proteins affecting viral entry into cells and virus infection efficiency by western blotting. We showed that cell cultures more sensitive to VV-GMCSF-Lact are characterized by a greater number of cells with CSC markers and a lower level of activated Akt kinase. Akt probably inhibits lactaptin-induced apoptosis in virus-resistant cells. Hence, we suggest that the sensitivity of glioblastoma cells to the oncotoxic effect of VV-GMCSF-Lact is determined by the nature and extent of the disturbances in cell death regulation in various cultures. Further investigation of the factors affecting glioblastoma resistance to virotherapy will test this hypothesis and identify targets for antitumor therapy, combined with VV-GMCSF-Lact.

High-throughput ex vivo drug testing identifies potential drugs and drug combinations for NRAS-positive malignant melanoma

Therapy options for patients with metastatic melanoma (MM) have considerably improved over the past decade. However, many patients still need effective therapy after unsuccessful immunotherapy, especially patients with BRAF-negative tumors who lack the option of targeted treatment second line. Therefore, the elucidation of efficient and personalized therapy options for these patients is required. In this study, three patient-derived cancer cells (PDCs) were established from NRAS Q61-positive MM patients. The response of PDCs and five established melanoma cell lines (two NRAS-positive, one wild type, and two BRAF V600-positive) was evaluated toward a panel of 527 oncology drugs using high-throughput drug sensitivity and resistance testing. The PDCs and cell lines displayed strong responses to MAPK inhibitors, as expected. Additionally, the PDCs and cell lines were responsive to PI3K/mTOR, mTOR, and PLK1 inhibitors among other effective drugs currently undergoing clinical trials. Combinations with a MEK inhibitor were tested with other targeted agents to identify effective synergies. MEK inhibitor showed synergy with multikinase inhibitor ponatinib, ABL inhibitor nilotinib, PI3K/mTOR inhibitor pictilisib, and pan-RAF inhibitor LY3009120. The application of the patients' cancer cells for functional drug testing ex vivo is one step further in the process of identifying potential agents and agent combinations to personalize treatment for patients with MM. Our preliminary study results suggest that this approach has the potential for larger-scale drug testing and personalized treatment applications in our expansion trial. Our results show that drug sensitivity and resistance testing may be implementable in the treatment planning of patients with MM.

Double Recombinant Vaccinia Virus: A Candidate Drug against Human Glioblastoma

Glioblastoma is one of the most aggressive brain tumors. Given the poor prognosis of this disease, novel methods for glioblastoma treatment are needed. Virotherapy is one of the most actively developed approaches for cancer therapy today. VV-GMCSF-Lact is a recombinant vaccinia virus with deletions of the viral thymidine kinase and growth factor genes and insertions of the granulocyte–macrophage colony-stimulating factor and oncotoxic protein lactaptin genes. The virus has high cytotoxic activity against human cancer cells of various histogenesis and antitumor efficacy against breast cancer. In this work, we show VV-GMCSF-Lact to be a promising therapeutic agent for glioblastoma treatment. VV-GMCSF-Lact effectively decreases the viability of glioblastoma cells of both immortalized and patient-derived cultures in vitro, crosses the blood–brain barrier, selectively replicates into orthotopically transplanted human glioblastoma when intravenously injected, and inhibits glioblastoma xenograft and metastasis growth when injected intratumorally.

MicroRNA-670-3p suppresses ferroptosis of human glioblastoma cells through targeting ACSL4

Glioblastoma is one of the most frequent malignant tumors derived from the brain in adults with very poor prognosis. Ferroptosis is implicated in the initiation and progression of various tumors, including the glioblastoma. The present study aims to investigate the function of microRNA (miR)-670-3p in glioblastoma, and tries to demonstrate whether ferroptosis is involved in this process. Human glioblastoma cell lines, U87MG and A172, were transfected with the inhibitor, mimic and matched negative controls of miR-670-3p to manipulate intracellular miR-670-3p level. To validate the involvement of ferroptosis in miR-670-3p inhibitor-mediated tumor suppressive effects, ferrostain-1 and liproxstatin-1 were used to inhibit ferroptosis in the presence of miR-670-3p inhibitor. In addition, the small interfering RNA against acyl-CoA synthase long chain family member 4 (ACSL4) was used to knock down endogenous ACSL4 expression. To validate the combined effects between miR-670-3p inhibitor and temozolomide (TMZ), cells were pretreated with TMZ and then transfected with or without miR-670-3p inhibitor. miR-670-3p level was elevated in human glioblastoma, but decreased upon ferroptotic stimulation. miR-670-3p inhibitor suppressed, while miR-670-3p mimic promoted glioblastoma cell growth through modulating ferroptosis. Mechanistically, ACSL4 was required for the regulation on ferroptosis and growth of glioblastoma cells by miR-670-3p. Moreover, U87MG and A172 cells treated with miR-670-3p inhibitor showed an increased chemosensitivity to TMZ. We prove that miR-670-3p suppresses ferroptosis of human glioblastoma cells through targeting ACSL4, and that inhibiting miR-670-3p can be an alternative, at least adjuvant strategy to treat glioblastoma.

The effect of fascin 1 inhibition on head and neck squamous cell carcinoma cells

Fascin 1 plays important pro-metastatic roles in head and neck carcinoma (HNSCC) migration, invasion, and metastasis. However, limited advancement in targeting metastasis remains a major obstacle in improving HNSCC patients' survival. Therefore, we assessed the therapeutic potential of fascin 1 targeted inhibition and its potential prognostic value in HNSCC patients. Using in vitro and in vivo approaches, we investigated the effect of compound G2, a novel fascin 1 inhibitor, on HNSCC cells migration, invasion, and metastasis. High-throughput screening (HTS) was used to assess cytotoxic activity of compound G2 alone or combined with irradiation. We also evaluated the prognostic potential of fascin 1 in HNSCC patients. Interestingly, compound G2 reduced carcinoma cells migration and invasion in vitro and inhibited metastasis in vivo. Moreover, HTS revealed a modest cytotoxic activity of the compound G2 on HNSCC cell lines. Irradiation did not synergistically enhance the compound G2-mediated cytotoxic activity. Survival analyses showed that high fascin 1 immunoexpression, at the tumor invasive front, was associated with cancer-specific mortality in the advanced stages of HNSCC. Collectively, our findings suggest that fascin 1 represents a promising anti-metastatic therapeutic target and a useful prognostic marker in patients with HNSCC. Novel anti-metastatic agents could provide a valuable addition to cancer therapy.

The important role of routine cytopathology in pediatric precision oncology

BACKGROUND

The development of high-throughput drug screening (HTS) using primary cultures provides a promising, clinically translatable approach to tailoring treatment strategies for patients with cancer. However, this has been challenging for solid tumors because of often limited amounts of tissue available. In most cases, in vitro expansion is required before HTS, which may lead to overgrowth and contamination by non-neoplastic cells.

METHODS

In this study, hematoxylin and eosin staining and immunohistochemical staining were performed on 129 cytopathology cases from 95 patients. These cytopathology cases comprised cell block preparations derived from primary tumor specimens or patient-derived xenografts as part of a pediatric precision oncology trial. Cytopathology cases were compared with the morphology and immunohistochemical staining profile of the original tumor. Cases were reported as tumor cells present, equivocal, or tumor cells absent. The HTS results from cytopathologically validated cultures were incorporated into a multidisciplinary tumor board report issued to the treating clinician to guide clinical decision making.

RESULTS

On cytopathologic examination, tumor cells were present in 77 of 129 cases (60%) and were absent in 38 of 129 cases (29%), whereas 14 of 129 cases (11%) were equivocal. Cultures that contained tumor cells resembled the tumors from which they were derived.

CONCLUSIONS

Cytopathologic examination of tumor cell block preparations is feasible and provides detailed morphologic characterization. Cytopathologic examination is essential for ensuring that samples submitted for HTS contain representative tumor cells and that in vitro drug sensitivity data are clinically translatable.

Designing precision medicine panels for drug refractory cancers targeting cancer stemness traits

Cancer is one amongst the major causes of death today and cancer biology is one of the most well researched fields in medicine. The driving force behind cancer is considered to be a minor subpopulation of cells, the cancer stem cells (CSCs). Similar to other stem cells, these cells are self-renewing and proliferating but CSCs are also difficult to target by chemo- or radio-therapies. Cancer stem cells are known to be present in most of the cancer subgroups such as carcinoma, sarcoma, myeloma, leukemia, lymphomas and mixed cancer types. There is a wide gamut of factors attributed to the stemness of cancers, ranging from dysregulated signaling pathways, and activation of enzymes aiding immune evasion, to conducive tumor microenvironment, to name a few. The defining outcome of the increased presence of CSCs is tumor metastasis and relapse. Predictive medicine approach based on the plethora of CSC markers would be a move towards precision medicine to specifically identify CSC-rich tumors. In this review, we discuss the cancer subtypes and the role of different CSC specific markers in these varying subtypes. We also categorize the CSC markers based their defining trait contributing to stemness. This review thus provides a comprehensive approach to catalogue a predictive set of markers to identify the resistant and refractory cancer stem cell population within different tumor subtypes, so as to facilitate better prognosis and targeted therapeutic strategies.

Robot technology identifies a Parkinsonian therapeutics repurpose to target stem cells of glioblastoma

Aim: Glioblastoma is a heterogeneous lethal disease, regulated by a stem-cell hierarchy and the neurotransmitter microenvironment. The identification of chemotherapies targeting individual cancer stem cells is a clinical need. Methodology: A robotic workstation was programmed to perform a drug concentration to cell-growth analysis on an in vitro model of glioblastoma stem cells (GSCs). Mode-of-action analysis of the selected top substance was performed with manual repetition assays and acquisition of further parameters. Results: We identified 22 therapeutic potential substances. Three suggested a repurpose potential of neurotransmitter signal-modulating agents to target GSCs, out of which the Parkinson's therapeutic trihexyphenidyl was most effective. Manual repetition assays and initial mode of action characterization revealed suppression of cell proliferation, cell cycle and survival. Conclusion: Anti-neurotransmitter signaling directed therapy has potential to target GSCs. We established a drug testing facility that is able to define a mid-scale chemo responsome of in vitro cancer models, possibly also suitable for other cell systems.

Roles of TP53 gene in the development of resistance to PI3K inhibitor resistances in CRISPR-Cas9-edited lung adenocarcinoma cells

The mutation rates of tumor suppressor protein p53 gene (TP53) are high in lung adenocarcinoma and promote the development of acquired drug resistance. The present study evaluated the p53-dependent role in lung cancer cell sensitivity to PI3K-specific inhibitors, PI3K-associated inhibitors, PI3K-non-related inhibitors, and protein-based stimuli using designed p53 mutation. We found that the deletion of p53 key regions from amino acid 96 to 393 with the CRISPR-Cas9 altered multi-dimensional structure and sequencing of p53, probably leading the secondary changes in chemical structures and properties of PI3K subunit proteins or in interactions between p53 and PI3K isoform genes. The p53-dependent cell sensitivity varied among target specificities, drug chemical properties, mechanism-specific signal pathways, and drug efficacies, independently upon the size of molecules. The effects of the designed p53 mutation highly depend upon p53-involved molecular mechanisms in the cell. Our results indicate that lung cancer cell resistance to drug can develop with dynamic formations of p53 mutations changing the cell sensitivity. This may explain the real-time occurrence of cancer cell resistance to drug treatment, during which drugs may induce the new mutations of p53. Thus, it is important to dynamically monitor the formation of new mutations during the therapy and discover new drug resistance-specific targets.