Search Results (10)

Background/objectives: Hypoxia in the tumor microenvironment is linked to aggressiveness, epithelial–mesenchymal transition, metastasis, and therapy resistance. Targeting hypoxia to enhance antitumor immunity is crucial for overcoming therapeutic resistance. Here, we investigated the ability of Evofosfamide, a prodrug that gets activated under hypoxic conditions, to sensitize breast cancer cells to cell death. Evofosfamide is converted into bromo-isophosphoramide mustard, a potent DNA cross-linking agent that is expected to enhance the killing of cancer cells under hypoxic conditions, where these cells typically exhibit resistance. Methods: Representative breast cancer cell lines, MCF-7 and MDA-MB-231, were treated with Evofosfamide under normoxia and hypoxia. Changes in cell viability and the mechanism of cell death were measured using neutral red dye uptake, Annexin-FITC/propidium iodide staining, and Western blot analysis of markers—PARP1 and caspase 3/7. We tested Evofosfamide’s ability to counteract hypoxic suppression of type I Interferon signaling genes using quantitative PCR (qPCR), as well as its capacity to trigger natural killer (NK)-cell-mediated cytotoxicity. Results: Evofosfamide enhanced cell killing in both MCF-7 and MDA-MB-231 cells under hypoxic conditions compared to normoxic conditions. Cell killing was accompanied by increased cellular reactive oxygen species (ROS), diminished mitochondrial membrane potential, and induction of apoptosis, as demonstrated by the fragmentation or laddering of genomic DNA, the activation of caspase 3/7, and the cleavage of PARP. qPCR analysis revealed that Evofosfamide was capable of restoring type I interferon signaling in hypoxic breast cancer cells, leading to the subsequent cytolytic activity of NK cells against the tumor cells. Conclusions: Thus, conditioning the breast cancer cells with Evofosfamide resulted in enhanced cell killing under hypoxia, further underscoring its potential as a sensitizer to target hypoxia-driven tumors. Full article

Background/Objectives: Locally advanced and metastatic leiomyosarcoma (LMS) is an aggressive cancer with limited treatment options. This single-institution, retrospective study evaluated the efficacy of first-line chemotherapy regimens in patients with advanced or metastatic LMS treated at Stanford Medical Center. Methods: Seventy-four patients with unresectable or metastatic LMS were deemed eligible and treated with first-line chemotherapy regimens, including gemcitabine plus docetaxel, dacarbazine, doxorubicin combinations (with evofosfamide or ifosfamide), and doxorubicin monotherapy. Progression-free survival (PFS), overall survival (OS), and disease control rate (DCR) were assessed using RECIST v1.1, with survival analyses performed using Kaplan–Meier and Cox proportional hazards methods. Results: The cohort consisted of 56 females (75.7%) and 18 males (24.3%), with a median age of 55.5 years. The majority (93.2%) had metastatic disease. The median PFS for the entire cohort was 4.9 months (range: 0.6–28.1 mo), and the median OS was 27.3 months (range: 1.9–140.2 mo). The doxorubicin combination (DC) group had the highest median PFS of 7.9 months (range: 0.6–15.8 mo). Doxorubicin alone had the highest median OS of 33.8 months (4.2–100.2 mo). Doxorubicin combinations demonstrated superior PFS in both uterine and non-uterine LMS subgroups. Conclusions: These findings reaffirm the efficacy of doxorubicin-based combination regimens as a first-line treatment for locally advanced and metastatic LMS, particularly in non-uterine LMS. Full article

The kinetic parameters for the release of anticancer effectors from the radical anions of prodrugs through fragmentation have been measured under conditions that model the interfacial region where the enzymatic reduction in the prodrugs takes place. While the back-oxidation of the radical anions via O₂ mainly occurs under normoxia, preventing radical anion fragmentation, this is not the case for the lower concentrations of O₂ found in hypoxic regions of tumors. Rate-constant data show that O₂ concentrations known to bring about a 50% decrease in the level of cell kill arising from the prodrugs in anoxia (the K-value) do not significantly inhibit the fragmentation of radical anions. Evidence is put forward suggesting that radical anions can undergo an electron transfer to ubiquinone (CoQ₁₀, UQ) in competition with the fragmentation of the radical anions releasing effectors. The prior inhibition of the synthesis of UQ in cells is put forward as a possible approach to increase the effectiveness of such prodrugs in killing hypoxic tumor cells. Full article

The transcription factor hypoxia-inducible factor 1α (HIF-1α) drives metabolic reprogramming in gliomas (GLs) under hypoxic conditions, promoting glycolysis for tumor development. Evofosfamide (EVO) releases a DNA-alkylating agent within hypoxic regions, indicating that it may serve as a hypoxia-targeted therapy. The aim of this study was to investigate the glycolytic metabolism and antitumor effects of EVO in a canine GL model. Our clinical data showed that overall survival was significantly decreased in GL dog patients with higher HIF-1α expression compared to that of those with lower HIF-1α expression, and there was a positive correlation between HIF-1α and pyruvate dehydrogenase kinase 1 (PDK1) expression, suggesting that glycolytic activity under hypoxia conditions may contribute to poor outcomes in canine GL. Our glycolysis assay tests showed that the glycolytic ATP level was higher than the mitochondrial ATP level in three types of canine GL cell lines by activating the HIF-1 signal pathway under hypoxia conditions, resulting in an overall increase in total cellular ATP production. However, treatment with EVO inhibited the glycolytic ATP level in the GL cell lines under hypoxia conditions by targeting HIF-1α-positive cells, leading to decrease in total cellular ATP production. Our in vivo tests showed that EVO significantly reduced tumor development compared to controls and temozolomide in murine GL models. A metabolic analysis demonstrated that EVO effectively suppressed glycolytic metabolism by eliminating HIF-1α-positive cells, suggesting that it may restore metabolism in canine GLs. The evidence presented here supports the favorable preclinical evaluation of EVO as a potential improvement in cancer metabolism. Full article

Purpose: Success of clinical trials increasingly relies on effective selection of the target patient populations. We hypothesize that computational analysis of pre-accrual imaging data can be used for patient enrichment to better identify patients who can potentially benefit from investigational agents. Methods: This was tested retrospectively in soft-tissue sarcoma (STS) patients accrued into a randomized clinical trial (SARC021) that evaluated the efficacy of evofosfamide (Evo), a hypoxia activated prodrug, in combination with doxorubicin (Dox). Notably, SARC021 failed to meet its overall survival (OS) objective. We tested whether a radiomic biomarker-driven inclusion/exclusion criterion could have been used to improve the difference between the two arms (Evo + Dox vs. Dox) of the study. 164 radiomics features were extracted from 296 SARC021 patients with lung metastases, divided into training and test sets. Results: A single radiomics feature, Short Run Emphasis (SRE), was representative of a group of correlated features that were the most informative. The SRE feature value was combined into a model along with histological classification and smoking history. This model as able to identify an enriched subset (52%) of patients who had a significantly longer OS in Evo + Dox vs. Dox groups [p = 0.036, Hazard Ratio (HR) = 0.64 (0.42–0.97)]. Applying the same model and threshold value in an independent test set confirmed the significant survival difference [p = 0.016, HR = 0.42 (0.20–0.85)]. Notably, this model was best at identifying exclusion criteria for patients most likely to benefit from doxorubicin alone. Conclusions: The study presents a first of its kind clinical-radiomic approach for patient enrichment in clinical trials. We show that, had an appropriate model been used for selective patient inclusion, SARC021 trial could have met its primary survival objective for patients with metastatic STS. Full article

The magnitude of the host immune response can be regulated by either stimulatory or inhibitory immune checkpoint molecules. Receptor-ligand binding between inhibitory molecules is often exploited by tumours to suppress anti-tumour immune responses. Immune checkpoint inhibitors that block these inhibitory interactions can relieve T-cells from negative regulation, and have yielded remarkable activity in the clinic. Despite this success, clinical data reveal that durable responses are limited to a minority of patients and malignancies, indicating the presence of underlying resistance mechanisms. Accumulating evidence suggests that tumour hypoxia, a pervasive feature of many solid cancers, is a critical phenomenon involved in suppressing the anti-tumour immune response generated by checkpoint inhibitors. In this review, we discuss the mechanisms associated with hypoxia-mediate immunosuppression and focus on modulating tumour hypoxia as an approach to improve immunotherapy responsiveness. Full article

Hypoxia is a hallmark of many solid tumors and is associated with resistance to anticancer treatments. Hypoxia-activated prodrugs (HAPs) were developed to target the hypoxic regions of these tumors. Among 2nd generation HAPs, Evofosfamide (Evo, also known as TH-302) exhibits preclinical and clinical activities against adult glioblastoma. In this study, we evaluated its potential in the field of pediatric neuro-oncology. We assessed the efficacy of Evo in vitro as a single drug, or in combination with SN38, doxorubicin, and etoposide, against three pediatric high-grade glioma (pHGG) and three diffuse intrinsic pontine glioma (DIPG) cell lines under hypoxic conditions. We also investigated radio-sensitizing effects using clonogenic assays. Evo inhibited the growth of all cell lines, mainly under hypoxia. We also highlighted a significant synergism between Evo and doxorubicin, SN38, or etoposide. Finally, Evo radio-sensitized the pHGG cell line tested, both with fractionated and single-dose irradiation schedules. Altogether, we report here the first preclinical proof of evidence about Evofosfamide efficiency against hypoxic pHGG and DIPG cells. Since such tumors are highly hypoxic, and Evo potentiates the effect of ionizing radiation and chemotherapy, it appears as a promising therapeutic strategy for children with brain tumors. Full article

Background: The design and development of prodrugs is the most common and effective strategy to overcome pharmacokinetic and pharmacodynamic drawbacks of active drugs. A respected number of prodrugs have been reached the drugs market throughout history and the recent years have witnessed a significant increase in the use of prodrugs as a replacement of their parent drugs for an efficient treatment of various ailment. Methods: A Scan conducted to find recent approved prodrugs and prodrugs in development. Results: Selected prodrugs were reported and categorized in accordance to their target systems. Conclusions: the prodrug approach has shown many successes and still remains a viable and effective approach to deliver new active agents. This conclusion is supported by the recent approved prodrugs and the scan of clinical trials conducted between 2013–2018. Full article

Tumour hypoxia is a marker of poor prognosis and failure of chemoradiotherapy in head and neck squamous cell carcinoma (HNSCC), providing a strategy for therapeutic intervention in this setting. To evaluate the utility of the hypoxia-activated prodrug evofosfamide (TH-302) in HNSCC, we established ten early passage patient-derived xenograft (PDX) models of HNSCC that were characterised by their histopathology, hypoxia status, gene expression, and sensitivity to evofosfamide. All PDX models closely resembled the histology of the patient tumours they were derived from. Pimonidazole-positive tumour hypoxic fractions ranged from 1.7–7.9% in line with reported HNSCC clinical values, while mRNA expression of the Toustrup hypoxia gene signature showed close correlations between PDX and matched patient tumours, together suggesting the PDX models may accurately model clinical tumour hypoxia. Evofosfamide as a single agent (50 mg/kg IP, qd × 5 for three weeks) demonstrated antitumour efficacy that was variable across the PDX models, ranging from complete regressions in one p16-positive PDX model to lack of significant activity in the three most resistant models. Despite all PDX models showing evidence of tumour hypoxia, and hypoxia being essential for activation of evofosfamide, the antitumour activity of evofosfamide only weakly correlated with tumour hypoxia status determined by pimonidazole immunohistochemistry. Other candidate evofosfamide sensitivity genes—MKI67, POR, and SLFN11—did not strongly influence evofosfamide sensitivity in univariate analyses, although a weak significant relationship with MKI67 was observed, while SLFN11 expression was lost in PDX tumours. Overall, these data confirm that evofosfamide has antitumour activity in clinically-relevant PDX tumour models of HNSCC and support further clinical evaluation of this drug in HNSCC patients. Further research is required to identify those factors that, alongside hypoxia, can influence sensitivity to evofosfamide and could act as predictive biomarkers to support its use in precision medicine therapy of HNSCC. Full article

High-grade gliomas are often characterized by hypoxia, which is associated with both poor long-term prognosis and therapy resistance. The adverse role hypoxia plays in treatment resistance and disease progression has led to the development of hypoxia imaging methods and hypoxia-targeted treatments. Here, we determined the tumor hypoxia and vascular perfusion characteristics of 2 rat orthotopic glioma models using 18-fluoromisonidozole positron emission tomography. In addition, we determined tumor response to the hypoxia-activated prodrug evofosfamide (TH-302) in these rat glioma models. C6 tumors exhibited more hypoxia and were less perfused than 9L tumors. On the basis of these differences in their tumor hypoxic burden, treatment with evofosfamide resulted in 4- and 2-fold decreases in tumor growth rates of C6 and 9L tumors, respectively. This work shows that imaging methods sensitive to tumor hypoxia and perfusion are able to predict response to hypoxia-targeted agents. This has implications for improved patient selection, particularly in clinical trials, for treatment with hypoxia-activated cytotoxic prodrugs, such as evofosfamide. Full article