Manijeh Daneshmand

Randomized dose-finding clinical trial of oncolytic immunotherapeutic vaccinia JX-594 in liver cancer

Oncolytic viruses and active immunotherapeutics have complementary mechanisms of action (MOA) that are both self amplifying in tumors, yet the impact of dose on subject outcome is unclear. JX-594 (Pexa-Vec) is an oncolytic and immunotherapeutic vaccinia virus. To determine the optimal JX-594 dose in subjects with advanced hepatocellular carcinoma (HCC), we conducted a randomized phase 2 dose-finding trial (n = 30). Radiologists infused low- or high-dose JX-594 into liver tumors (days 1, 15 and 29); infusions resulted in acute detectable intravascular JX-594 genomes. Objective intrahepatic Modified Response Evaluation Criteria in Solid Tumors (mRECIST) (15%) and Choi (62%) response rates and intrahepatic disease control (50%) were equivalent in injected and distant noninjected tumors at both doses. JX-594 replication and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression preceded the induction of anticancer immunity. In contrast to tumor response rate and immune endpoints, subject survival duration was significantly related to dose (median survival of 14.1 months compared to 6.7 months on the high and low dose, respectively; hazard ratio 0.39; P = 0.020). JX-594 demonstrated oncolytic and immunotherapy MOA, tumor responses and dose-related survival in individuals with HCC.

Intravenous delivery of a multi-mechanistic cancer-targeted oncolytic poxvirus in humans

The efficacy and safety of biological molecules in cancer therapy, such as peptides and small interfering RNAs (siRNAs), could be markedly increased if high concentrations could be achieved and amplified selectively in tumour tissues versus normal tissues after intravenous administration. This has not been achievable so far in humans. We hypothesized that a poxvirus, which evolved for blood-borne systemic spread in mammals, could be engineered for cancer-selective replication and used as a vehicle for the intravenous delivery and expression of transgenes in tumours. JX-594 is an oncolytic poxvirus engineered for replication, transgene expression and amplification in cancer cells harbouring activation of the epidermal growth factor receptor (EGFR)/Ras pathway, followed by cell lysis and anticancer immunity. Here we show in a clinical trial that JX-594 selectively infects, replicates and expresses transgene products in cancer tissue after intravenous infusion, in a dose-related fashion. Normal tissues were not affected clinically. This platform technology opens up the possibility of multifunctional products that selectively express high concentrations of several complementary therapeutic and imaging molecules in metastatic solid tumours in humans.

Use of a targeted oncolytic poxvirus, JX-594, in patients with refractory primary or metastatic liver cancer: a phase I trial

BACKGROUND JX-594 is a targeted oncolytic poxvirus designed to selectively replicate in and destroy cancer cells with cell-cycle abnormalities and epidermal growth factor receptor (EGFR)-ras pathway activation. Direct oncolysis plus granulocyte-macrophage colony-stimulating factor (GM-CSF) expression also stimulates shutdown of tumour vasculature and antitumoral immunity. We aimed to assess intratumoral injection of JX-594 in patients with refractory primary or metastatic liver cancer. METHODS Between Jan 4, 2006, and July 4, 2007, 14 patients with histologically confirmed refractory primary or metastatic liver tumours (up to 10.9 cm total diameter) that were amenable to image-guided intratumoral injections were enrolled into this non-comparative, open-label, phase I dose-escalation trial (standard 3x3 design; two to six patients for each dose with 12-18 estimated total patients). Patients received one of four doses of intratumoral JX-594 (10(8) plaque-forming units [pfu], 3x10(8) pfu, 10(9) pfu, or 3x10(9) pfu) every 3 weeks at Dong-A University Hospital (Busan, South Korea). Patients were monitored after treatment for at least 48 h in hospital and for at least 4 weeks as out-patients. Adverse event-monitoring according to the National Cancer Institute Common Toxicity Criteria (version 3) and standard laboratory toxicity grading for haematology, liver and renal function, coagulation studies, serum chemistry, and urinalysis were done. The primary aims were to ascertain the maximum-tolerated dose (MTD) and safety of JX-594 treatment. Data were also collected on pharmacokinetics, pharmacodynamics, and efficacy. Analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT00629759. FINDINGS Of 22 patients with liver tumours who were assessed for eligibility, eight patients did not meet inclusion criteria. Therefore, 14 patients, including those with hepatocellular, colorectal, melanoma, and lung cancer, were enrolled. Patients were heavily pretreated (5.6 previous treatments, SD 2.8, range 2.0-12.0) and had large tumours (7.0 cm diameter, SD 2.7, range 1.8-10.9). Patients received a mean of 3.4 (SD 2.2, range 1.0-8.0) cycles of JX-594. All patients were evaluable for toxicity. All patients experienced grade I-III flu-like symptoms, and four had transient grade I-III dose-related thrombocytopenia. Grade III hyperbilirubinaemia was dose-limiting in both patients at the highest dose; the MTD was therefore 1x10(9) pfu. JX-594 replication-dependent dissemination in blood was shown, with resultant infection of non-injected tumour sites. GM-CSF expression resulted in grade I-III increases in neutrophil counts in four of six patients at the MTD. Tumour responses were shown in injected and non-injected tumours. Ten patients were radiographically evaluable for objective responses; non-evaluable patients had contraindications to contrast medium (n=2) or no post-treatment scans (n=2). According to Response Evaluation Criteria in Solid Tumors (RECIST), three patients had partial response, six had stable disease, and one had progressive disease. INTERPRETATION Intratumoral injection of JX-594 into primary or metastatic liver tumours was generally well-tolerated. Direct hyperbilirubinaemia was the dose-limiting toxicity. Safety was acceptable in the context of JX-594 replication, GM-CSF expression, systemic dissemination, and JX-594 had anti-tumoral effects against several refractory carcinomas. Phase II trials are now underway.

A mechanistic proof-of-concept clinical trial with JX-594, a targeted multi-mechanistic oncolytic poxvirus, in patients with metastatic melanoma.

JX-594 is a targeted and granulocyte macrophage-colony stimulating factor (GM-CSF)-expressing oncolytic poxvirus designed to selectively replicate in and destroy cancer cells through viral oncolysis and tumor-specific immunity. In order to study the mechanisms-of-action (MOA) of JX-594 in humans, a mechanistic proof-of-concept clinical trial was performed at a low dose equivalent to ≤10% of the maximum-tolerated dose (MTD) in other clinical trials. Ten patients with previously treated stage IV melanoma were enrolled. Tumors were injected weekly for up to nine total treatments. Blood samples and tumor biopsies were analyzed for evidence of transgene activity, virus replication, and immune stimulation. The β-galactosidase (β-gal) transgene was expressed in all patients as evidenced by antibody induction. Six patients had significant induction of GM-CSF-responsive white blood cell (WBC) subsets such as neutrophils (25-300% increase). JX-594 replication and subsequent shedding into blood was detectable in five patients after cycles 1-9. Tumor biopsies demonstrated JX-594 replication, perivascular lymphocytic infiltration, and diffuse tumor necrosis. Mild flu-like symptoms were the most common adverse events. In sum, JX-594 replication, oncolysis, and expression of both transgenes were demonstrated; replication was still evident after multiple cycles. These findings have implications for further clinical development of JX-594 and other transgene-armed oncolytic viruses.

Oncolytic Vaccinia Virus Disrupts Tumor-Associated Vasculature in Humans

Efforts to selectively target and disrupt established tumor vasculature have largely failed to date. We hypothesized that a vaccinia virus engineered to target cells with activation of the ras/MAPK signaling pathway (JX-594) could specifically infect and express transgenes (hGM-CSF, β-galactosidase) in tumor-associated vascular endothelial cells in humans. Efficient replication and transgene expression in normal human endothelial cells in vitro required either VEGF or FGF-2 stimulation. Intravenous infusion in mice resulted in virus replication in tumor-associated endothelial cells, disruption of tumor blood flow, and hypoxia within 48 hours; massive tumor necrosis ensued within 5 days. Normal vessels were not affected. In patients treated with intravenous JX-594 in a phase I clinical trial, we showed dose-dependent endothelial cell infection and transgene expression in tumor biopsies of diverse histologies. Finally, patients with advanced hepatocellular carcinoma, a hypervascular and VEGF-rich tumor type, were treated with JX-594 on phase II clinical trials. JX-594 treatment caused disruption of tumor perfusion as early as 5 days in both VEGF receptor inhibitor-naïve and -refractory patients. Toxicities to normal blood vessels or to wound healing were not evident clinically or on MRI scans. This platform technology opens up the possibility of multifunctional engineered vaccinia products that selectively target and infect tumor-associated endothelial cells, as well as cancer cells, resulting in transgene expression, vasculature disruption, and tumor destruction in humans systemically.

Targeting Tumor Vasculature With an Oncolytic Virus

Oncolytic viruses (OVs) have been engineered or selected for cancer cell-specific infection however, we have found that following intravenous administration of vesicular stomatitis virus (VSV), tumor cell killing rapidly extends far beyond the initial sites of infection. We show here for the first time that VSV directly infects and destroys tumor vasculature in vivo but leaves normal vasculature intact. Three-dimensional (3D) reconstruction of infected tumors revealed that the majority of the tumor mass lacks significant blood flow in contrast to uninfected tumors, which exhibit relatively uniform perfusion. VSV replication in tumor neovasculature and spread within the tumor mass, initiates an inflammatory reaction including a neutrophil-dependent initiation of microclots within tumor blood vessels. Within 6 hours of intravenous administration of VSV and continuing for at least 24 hours, we observed the initiation of blood clots within the tumor vasculature whereas normal vasculature remained clot free. Blocking blood clot formation with thrombin inhibitors prevented tumor vascular collapse. Our results demonstrate that the therapeutic activity of an OV can go far beyond simple infection and lysis of malignant cells.

First-in-man Study of Western Reserve Strain Oncolytic Vaccinia Virus: Safety, Systemic Spread, and Antitumor Activity

Oncolytic viral therapy utilizes a tumor-selective replicating virus which preferentially infects and destroys cancer cells and triggers antitumor immunity. The Western Reserve strain of vaccinia virus (VV) is the most virulent strain of VV in animal models and has been engineered for tumor selectivity through two targeted gene deletions (vvDD). We performed the first-in-human phase 1, intratumoral dose escalation clinical trial of vvDD in 16 patients with advanced solid tumors. In addition to safety, we evaluated signs of vvDD replication and spread to distant tumors, pharmacokinetics and pharmacodynamics, clinical and immune responses to vvDD. Dose escalation proceeded without dose-limiting toxicities to a maximum feasible dose of 3 × 10(9) pfu. vvDD replication in tumors was reproducible. vvDD genomes and/or infectious particles were recovered from injected (n = 5 patients) and noninjected (n = 2 patients) tumors. At the two highest doses, vvDD genomes were detected acutely in blood in all patients while delayed re-emergence of vvDD genomes in blood was detected in two patients. Fifteen of 16 patients exhibited late symptoms, consistent with ongoing vvDD replication. In summary, intratumoral injection of the oncolytic vaccinia vvDD was well-tolerated in patients and resulted in selective infection of injected and noninjected tumors and antitumor activity.

VEGF-Mediated Induction of PRD1-BF1/Blimp1 Expression Sensitizes Tumor Vasculature to Oncolytic Virus Infection.

Oncolytic viruses designed to attack malignant cells can in addition infect and destroy tumor vascular endothelial cells. We show here that this expanded tropism of oncolytic vaccinia virus to the endothelial compartment is a consequence of VEGF-mediated suppression of the intrinsic antiviral response. VEGF/VEGFR2 signaling through Erk1/2 and Stat3 leads to upregulation, nuclear localization, and activation of the transcription repressor PRD1-BF1/Blimp1. PRD1-BF1 does not contribute to the mitogenic effects of VEGF, but directly represses genes involved in type I interferon (IFN)-mediated antiviral signaling. In vivo suppression of VEGF signaling diminishes PRD1-BF1/Blimp1 expression in tumor vasculature and inhibits intravenously administered oncolytic vaccinia delivery to and consequent spread within the tumor.

ORFV: A Novel Oncolytic and Immune Stimulating Parapoxvirus Therapeutic

Replicating viruses for the treatment of cancer have a number of advantages over traditional therapeutic modalities. They are highly targeted, self-amplifying, and have the added potential to act as both gene-therapy delivery vehicles and oncolytic agents. Parapoxvirus ovis or Orf virus (ORFV) is the prototypic species of the Parapoxvirus genus, causing a benign disease in its natural ungulate host. ORFV possesses a number of unique properties that make it an ideal viral backbone for the development of a cancer therapeutic: it is safe in humans, has the ability to cause repeat infections even in the presence of antibody, and it induces a potent T(h)-1-dominated immune response. Here, we show that live replicating ORFV induces an antitumor immune response in multiple syngeneic mouse models of cancer that is mediated largely by the potent activation of both cytokine-secreting, and tumoricidal natural killer (NK) cells. We have also highlighted the clinical potential of the virus by demonstration of human cancer cell oncolysis including efficacy in an A549 xenograft model of cancer.

A New Spontaneously Transformed Syngeneic Model of High-Grade Serous Ovarian Cancer with a Tumor-Initiating Cell Population

Improving screening and treatment options for patients with epithelial ovarian cancer has been a major challenge in cancer research. Development of novel diagnostic and therapeutic approaches, particularly for the most common subtype, high-grade serous ovarian cancer (HGSC), has been hampered by controversies over the origin of the disease and a lack of spontaneous HGSC models to resolve this controversy. Over long-term culture in our laboratory, an ovarian surface epithelial (OSE) cell line spontaneously transformed OSE (STOSE). The objective of this study was to determine if the STOSE cell line is a good model of HGSC. STOSE cells grow faster than early passage parental M0505 cells with a doubling time of 13 and 48 h, respectively. STOSE cells form colonies in soft agar, an activity for which M0505 cells have negligible capacity. Microarray analysis identified 1755 down-regulated genes and 1203 up-regulated genes in STOSE compared to M0505 cells, many associated with aberrant Wnt/β-catenin and Nf-κB signaling. Upregulation of Ccnd1 and loss of Cdkn2a in STOSE tumors is consistent with changes identified in human ovarian cancers by The Cancer Genome Atlas. Intraperitoneal injection of STOSE cells into severe combined immunodeficient and syngeneic FVB/N mice produced cytokeratin+, WT1+, inhibin−, and PAX8+ tumors, a histotype resembling human HGSC. Based on evidence that a SCA1+ stem cell-like population exists in M0505 cells, we examined a subpopulation of SCA1+ cells that is present in STOSE cells. Compared to SCA1− cells, SCA1+ STOSE cells have increased colony-forming capacity and form palpable tumors 8 days faster after intrabursal injection into FVB/N mice. This study has identified the STOSE cells as the first spontaneous murine model of HGSC and provides evidence for the OSE as a possible origin of HGSC. Furthermore, this model provides a novel opportunity to study how normal stem-like OSE cells may transform into tumor-initiating cells.