Marc García-Moure

Abstract CT027: Oncolytic virus DNX-2401 with a short course of temozolomide for glioblastoma at first recurrence: Clinical data and prognostic biomarkers

DNX-2401 is a replication competent oncolytic adenovirus that has shown a potent antitumor effect in preclinical glioma models and a safe profile when administer as a single agent in glioma patients. Previously, our group showed that combination of DNX-2401 with temozolomide significantly increased the survival of mice bearing gliomas. Even though virotherapy is becoming a real therapeutic option still the precise mechanism of action, the interplay with the tumor microenvironment and biomarkers that predict response remain elusive. The main objective of this clinical trial was to investigate safety, OR, and OS following treatment with DNX-2401 and temozolomide. In addition, we aim to seek biomarkers that predict response to the virus. We included 31 glioma patients at first recurrence after prior surgery and standard treatment with radiotherapy, and temozolomide. Tumor resection or biopsy was performed to confirm recurrent disease. All patients received a single intraparenchymal injection of DNX-2401 (3x1010 vp) followed by 4 cycles of 150 mg/m2 temozolomide 2-4 weeks later. Ninety-four percent of patients completed all 4 planned cycles. The safety objective of the trial was achieved with no severe toxicities related to DNX-2401. Grade 3-4 adverse events were consistent with those associated with temozolomide (e.g., lymphopenia) or underlying disease. Several objective responses were observed with three patients alive 30, 19 and 27 months after treatment. The study is ongoing and results will be updated. Patients with higher titers of neutralizing antibodies prior to virus administration appeared to respond better to treatment. No differences were seen in the levels of serum cytokines amongst patients and treatment times. FGF2 is a growth factor that has been shown to increased cell susceptibility to virus infection and replication through inhibition of the interferon pathway. Interestingly, high expression of FGF2 in tumor samples was associated with significantly longer overall survival. FGF2 expression was inversely correlated with IFN-γ expression in the tumor and in exosomes isolated from liquid biopsies in the same patient. These data also suggest that patients with stronger innate responses did worse than those where the IFN pathway was downregulated. In summary, our data demonstrate that DNX-2401 in combination with temozolomide is well tolerated, can be safely administered and shows therapeutic activity. Moreover, FGF2 as a prognostic biomarker of DNX-2401 treatment response deserves further investigation. Citation Format: Marta M. Alonso, Marc Garcia-Moure, Marisol Gonzalez-Huarriz, Miguel Marigil, Ruben Hernandez-Alcoceba, Maria Bunales, Sandra Hervas, Jaime Gallego, Candelaria Gomez-Manzano, Juan Fueyo, Frederick Lang, Joanna Peterkin, Ricardo Diez-Valle, Sonia Tejada. Oncolytic virus DNX-2401 with a short course of temozolomide for glioblastoma at first recurrence: Clinical data and prognostic biomarkers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT027. doi:10.1158/1538-7445.AM2017-CT027

Oncolytic adenoviruses as a therapeutic approach for osteosarcoma: A new hope

Osteosarcoma is the most common bone cancer among those with non-hematological origin and affects mainly pediatric patients. In the last 50 years, refinements in surgical procedures, as well as the introduction of aggressive neoadjuvant and adjuvant chemotherapeutic cocktails, have increased to nearly 70% the survival rate of these patients. Despite the initial therapeutic progress the fight against osteosarcoma has not substantially improved during the last three decades, and almost 30% of the patients do not respond or recur after the standard treatment. For this group there is an urgent need to implement new therapeutic approaches. Oncolytic adenoviruses are conditionally replicative viruses engineered to selectively replicate in and kill tumor cells, while remaining quiescent in healthy cells. In the last years there have been multiple preclinical and clinical studies using these viruses as therapeutic agents in the treatment of a broad range of cancers, including osteosarcoma. In this review, we summarize some of the most relevant published literature about the use of oncolytic adenoviruses to treat human osteosarcoma tumors in subcutaneous, orthotopic and metastatic mouse models. In conclusion, up to date the preclinical studies with oncolytic adenoviruses have demonstrated that are safe and efficacious against local and metastatic osteosarcoma. Knowledge arising from phase I/II clinical trials with oncolytic adenoviruses in other tumors have shown the potential of viruses to awake the patient´s own immune system generating a response against the tumor. Generating osteosarcoma immune-competent adenoviruses friendly models will allow to better understand this potential. Future clinical trials with oncolytic adenoviruses for osteosarcoma tumors are warranted.

Spatial and temporal proteome dynamics of glioma cells during oncolytic adenovirus Delta-24-RGD infection

Glioblastoma multiforme (GBM) is the most common and aggressive type of malignant glioma. Oncolytic adenoviruses are being modified to exploit the aberrant expression of proteins in tumor cells to increase the antiglioma efficacy. E1A mutant adenovirus Delta-24-RGD (DNX-2401) has shown a favorable toxicity profile and remarkable efficacy in a first-in-human phase I clinical trial. However, the comprehensive modulation of glioma metabolism in response to Delta-24-RGD infection is poorly understood. Integrating mass spectrometry based-quantitative proteomics, physical and functional interaction data, and biochemical approaches, we conducted a cell-wide study of cytosolic, nuclear, and secreted glioma proteomes throughout the early time course of Delta-24-RGD infection. In addition to the severe proteostasis impairment detected during the first hours post-infection (hpi), Delta-24-RGD induces a transient inhibition of signal transducer and activator of transcription 3 (STAT3), and transcription factor AP-1 (c-JUN) between 3 and 10hpi, increasing the nuclear factor kappa B (NF-κB) activity at 6hpi. Furthermore, Delta-24-RGD specifically modulates the activation dynamics of protein kinase C (PKC), extracellular signal–regulated kinase 1/2 (ERK1/2), and p38 mitogen-activated protein kinase (p38 MAPK) pathways early in infection. At extracellular level, Delta-24-RGD triggers a time –dependent dynamic production of multitasking cytokines, and chemotactic factors, suggesting potential pleiotropic effects on the immune system reactivation. Taken together, these data help us to understand the mechanisms used by Delta-24-RGD to exploit glioma proteome organization. Further mining of this proteomic resource may enable design and engineering complementary adenoviral based-vectors to increase the specificity and potency against glioma.

The aberrant splicing of BAF45d links splicing regulation and transcription in glioblastoma

Background Glioblastoma, the most aggressive primary brain tumor, is genetically heterogeneous. Alternative splicing (AS) plays a key role in numerous pathologies, including cancer. The objectives of our study were to determine whether aberrant AS could play a role in the malignant phenotype of glioma and to understand the mechanism underlying its aberrant regulation. Methods We obtained surgical samples from patients with glioblastoma who underwent 5-aminolevulinic fluorescence-guided surgery. Biopsies were taken from the tumor center as well as from adjacent normal-appearing tissue. We used a global splicing array to identify candidate genes aberrantly spliced in these glioblastoma samples. Mechanistic and functional studies were performed to elucidate the role of our top candidate splice variant, BAF45d, in glioblastoma. Results BAF45d is part of the switch/sucrose nonfermentable complex and plays a key role in the development of the CNS. The BAF45d/6A isoform is present in 85% of over 200 glioma samples that have been analyzed and contributes to the malignant glioma phenotype through the maintenance of an undifferentiated cellular state. We demonstrate that BAF45d splicing is mediated by polypyrimidine tract-binding protein 1 (PTBP1) and that BAF45d regulates PTBP1, uncovering a reciprocal interplay between RNA splicing regulation and transcription. Conclusions Our data indicate that AS is a mechanism that contributes to the malignant phenotype of glioblastoma. Understanding the consequences of this biological process will uncover new therapeutic targets for this devastating disease.

Oncolytic Viruses as Therapeutic Tools for Pediatric Brain Tumors

In recent years, we have seen an important progress in our comprehension of the molecular basis of pediatric brain tumors (PBTs). However, they still represent the main cause of death by disease in children. Due to the poor prognosis of some types of PBTs and the long-term adverse effects associated with the traditional treatments, oncolytic viruses (OVs) have emerged as an interesting therapeutic option since they displayed safety and high tolerability in pre-clinical and clinical levels. In this review, we summarize the OVs evaluated in different types of PBTs, mostly in pre-clinical studies, and we discuss the possible future direction of research in this field. In this sense, one important aspect of OVs antitumoral effect is the stimulation of an immune response against the tumor which is necessary for a complete response in preclinical immunocompetent models and in the clinic. The role of the immune system in the response of OVs needs to be evaluated in PBTs and represents an experimental challenge due to the limited immunocompetent models of these diseases available for pre-clinical research.