Peter A. Forsyth

Recent progress in the battle between oncolytic viruses and tumours

In the past 5 years, the field of oncolytic virus research has matured significantly and is moving past the stage of being a laboratory novelty into a new era of preclinical and clinical trials. What have recent anticancer trials of oncolytic viruses taught us about this exciting new line of therapeutics?

Gelatinase-A (MMP-2), gelatinase-B (MMP-9) and membrane type matrix metalloproteinase-1 (MT1-MMP) are involved in different aspects of the pathophysiology of malignant gliomas.

SummaryMatrix metalloproteinases (MMPs) have been implicated as important factors in gliomas since they may both facilitate invasion into the surrounding brain and participate in neovascularization. We have tested the hypothesis that deregulated expression of gelatinase-A or B, or an activator of gelatinase-A, MT1-MMP, may contribute directly to human gliomas by quantifying the expression of these MMPs in 46 brain tumour specimens and seven control tissues. Quantitative RT-PCR and gelatin zymography showed that gelatinase-A in glioma specimens was higher than in normal tissue; these were significantly elevated in low grade gliomas and remained elevated in GBMs. Gelatinase-B transcript and activity levels were also higher than in normal brain and more strongly correlated with tumour grade. We did not see a close relationship between the levels of expression of MT1-MMP mRNA and amounts of activated gelatinase-A. In situ hybridization localized gelatinase-A and MT1-MMP transcripts to normal neuronal and glia, malignant glioma cells and blood vessels. In contrast, gelatinase-B showed a more restricted pattern of expression; it was strongly expressed in blood vessels at proliferating margins, as well as tumour cells in some cases. These data suggest that gelatinase-A, -B and MT1-MMP are important in the pathophysiology of human gliomas. The primary role of gelatinase-B may lie in remodelling associated with neovascularization, whereas gelatinase-A and MT1-MMP may be involved in both glial invasion and angiogenesis.

Headaches in patients with brain tumors: a study of 111 patients.

We examined 111 consecutive patients with primary or metastatic brain tumors identified by CT or MRI to characterize brain tumor headache. The median age was 44 years; 34% had primary and 66% metastatic tumors. Headaches were present in 48%, equally for primary and metastatic brain tumors. Headaches were similar to tension-type in 77%, migraine-type in 9%, and other types in 14%. The typical headache was bifrontal but worse ipsi-laterally, and was the worst symptom in only 45% of patients. Unlike true tension-type headaches, brain tumor headaches were worse with bending over in 32%, and nausea or vomiting was present in 40% of patients. The “classic” early morning brain tumor headache is uncommon. Nausea, vomiting, an abnormal neurologic examination, or a significant change in prior headache pattern suggest that the headache may be caused by a tumor.

Health-related quality of life in patients with glioblastoma: a randomised controlled trial

BACKGROUND A randomised controlled trial of radiotherapy alone versus radiotherapy with concomitant and adjuvant temozolomide for patients with glioblastoma showed that survival was higher for patients assigned combination treatment compared with those assigned standard radiotherapy alone. This paper reports the health-related quality of life (HRQOL) of the patients in this trial. METHODS 573 patients with newly diagnosed glioblastoma were randomly allocated either radiotherapy alone or radiotherapy and temozolomide. The primary endpoint was survival, and HRQOL was a secondary endpoint. We assessed HRQOL at baseline and at every 3 months during treatment until progression using the European Organisation for Research and Treatment of Cancer (EORTC) quality of life questionnaire core-30 (QLQ-C30) and the EORTC brain cancer module (EORTC BN-20). We calculated changes from baseline score for seven predefined HRQOL measures (fatigue, overall health, social function, emotional function, future uncertainty, insomnia, and communication deficit) and differences between groups for these measures at every time point. The significance of, and proportions of patients with, improved HRQOL scores--defined as a change of 10 points or more--were recorded. This trial is registered on the US National Cancer Institute website http://www.cancer.gov/search/NewClinicalTrials, NCT00006353. FINDINGS Baseline questionnaires were available for 490 (86%) patients. Baseline HRQOL scores did not differ between groups. At first follow-up, groups differed only in social functioning, favouring the radiotherapy-only group (mean score 79.0 [SD 3.2] for patients assigned radiotherapy vs 67.4 [2.7] for those assigned radiotherapy and temozolomide; difference between groups 11.6 points [95% CI 3.5-19.7], p=0.0052). Over subsequent assessments, HRQOL was much the same between treatment groups. INTERPRETATION Addition of temozolomide during and after radiotherapy for patients with newly diagnosed glioblastoma significantly improved survival without a negative effect on HRQOL.

Phase II Trial of Continuous Dose-Intense Temozolomide in Recurrent Malignant Glioma: RESCUE Study

PURPOSE Concomitant temozolomide (TMZ)/radiotherapy followed by adjuvant TMZ has increased survival in patients with glioblastoma multiforme (GBM). However, few options are effective for patients who experience treatment failure. We conducted a multicenter, phase II study to assess the efficacy and safety of continuous dose-intense TMZ for recurrent GBM. PATIENTS AND METHODS Patients with malignant glioma at progression after standard TMZ 150 to 200 mg/m(2) x 5 days in a 28-day cycle for three or more cycles were stratified by tumor type (anaplastic glioma group A, GBM, group B). Ninety-one patients with GBM were prospectively divided into three groups (early [B1], extended [B2], and rechallenge [B3]) according to the timing of progression during adjuvant therapy. All patients received continuous dose-intense TMZ 50 mg/m(2)/d for up to 1 year or until progression occurred. Response was assessed by using RECIST (Response Evaluation Criteria in Solid Tumors). Results A total of 116 of 120 patients were evaluable for efficacy. For patients with GBM, 6-month progression-free survival (PFS) was 23.9% (B1, 27.3%; B2, 7.4%; B3, 35.7%). One-year survival from time of study entry was 27.3%, 14.8%, and 28.6% for the B1, B2 and B3 groups, respectively. For patients with anaplastic glioma, 6-month PFS was 35.7%; 1-year survival was 60.7%. The most common grades 3 and 4 nonhematologic toxicities were nausea/vomiting (6.7%) and fatigue (5.8%). Grades 3 and 4 hematologic toxicities were uncommon. CONCLUSION Rechallenge with continuous dose-intense TMZ 50 mg/m(2)/d is a valuable therapeutic option for patients with recurrent GBM. Patients who experience progression during the first six cycles of conventional adjuvant TMZ therapy or after a treatment-free interval get the most benefit from therapy.

Broad antitumor and antiangiogenic activities of AG3340, a potent and selective MMP inhibitor undergoing advanced oncology clinical trials.

ABSTRACT: We studied AG3340, a potent metalloproteinase (MMP) inhibitor with pM affinities for inhibiting gelatinases (MMP‐2 and ‐9), MT‐MMP‐1 (MMP‐14), and collagenase‐3 (MMP‐13) in many tumor models. AG3340 produced dose‐dependent pharmacokinetics and was well tolerated after intraperitoneal (i.p.) and oral dosing in mice. Across human tumor models, AG3340 produced profound tumor growth delays when dosing began early or late after tumor implantation, although all established tumor types did not respond to AG3340. A dose‐response relationship was explored in three models: COLO‐320DM colon, MV522 lung, and MDA‐MB‐435 breast. Dose‐dependent inhibitions of tumor growth (over 12.5‐200 mg/kg given twice daily, b.i.d.) were observed in the colon and lung models; and in a third (breast), maximal inhibitions were produced by the lowest dose of AG3340 (50 mg/kg, b.i.d.) that was tested. In another model, AG3340 (100 mg/kg, once daily, i.p.) markedly inhibited U87 glioma growth and increased animal survival. AG3340 also inhibited tumor growth and increased the survival of nude mice bearing androgen‐independent PC‐3 prostatic tumors. In a sixth model, KKLS gastric, AG3340 did not inhibit tumor growth but potentiated the efficacy of Taxol. Importantly, AG3340 markedly decreased tumor angiogenesis (as assessed by CD‐31 staining) and cell proliferation (as assessed by bromodeoxyuridine incorporation), and increased tumor necrosis and apoptosis (as assessed by hematoxylin and eosin and TUNEL staining). These effects were model dependent, but angiogenesis was commonly inhibited. AG3340 had a superior therapeutic index to the cytotoxic agents, carboplatin and Taxol, in the MV522 lung cancer model. In combination, AG3340 enhanced the efficacy of these cytotoxic agents without altering drug tolerance. Additionally, AG3340 decreased the number of murine melanoma (B16‐F10) lesions arising in the lung in an intravenous metastasis model when given in combination with carboplatin or Taxol. These studies directly support the use of AG3340 in front‐line combination chemotherapy in ongoing clinical trials in patients with advanced malignancies of the lung and prostate.

Prospective study of paclitaxel-induced peripheral neuropathy with quantitative sensory testing.

Background. Paclitaxel-induced peripheral neuropathy (PN) may be severeand dose-limiting at initial doses ≥ 275 mg/M2, but itsneurotoxicity at doses ≤ 250 mg/M2 has been incompletelycharacterized. The purposes of this study were to characterize and quantifypaclitaxel-induced PN and to determine the utility of quantitative sensorytesting (QST). Methods. We prospectively examined clinically and by QST 37women with metastatic breast cancer, treated with paclitaxel (200–250mg/m2) (average number of cycles = 7.3 over an average of 20.1weeks). QST included thermal threshold (TT) and vibration threshold (VT).Results. Paresthesias appeared in 31 (84%) patients after an averageof 1.7 cycles and an average cumulative dose of 371.5 mg/M2. Symptomsoccurred after the first or second dose in 26 (84%) patients and thenstabilized in 10 (32%), improved in 13 (42%) despite continuedtreatment, resolved completely in 6 (19%), and were progressive in 2(7%). Paclitaxel was discontinued in only 1 (3%) patientbecause of neurotoxicity and no patient required dose reduction because ofPN. Thirty-six (97%) developed signs of PN. The most sensitive QSTwas great toe VT but QST did not predict or identify subclinical PN in anypatient. Neurologic syndromes other than PN developed in 12 (32%)patients, and 7 were due to metastatic cancer. Conclusions. 1)Paclitaxel-induced PN is mostly sensory, and begins after the first orsecond dose. At these doses the neuropathy is mild, and rarelydose-limiting. 2) QST quantified the neuropathy but was less sensitive thanthe clinical examination. 3) Knowledge of the features of paclitaxels PNallows it to be differentiated from other neurologic syndromes which maysignal tumor progression.

Proliferation of Human Glioblastoma Stem Cells Occurs Independently of Exogenous Mitogens

Primary glial tumors of the central nervous system, most commonly glioblastoma multiforme (GBM), are aggressive lesions with a dismal prognosis. Despite identification and isolation of human brain tumor stem cells (BTSCs), characteristics that distinguish BTSCs from neural stem cells remain to be elucidated. We cultured cells isolated from gliomas, using the neurosphere culture system, to understand their growth requirements. Both CD133+ and CD133− adult GBM BTSCs proliferated in the absence of exogenous mitogenic stimulation and gave rise to multipotent GBM spheres that were capable of self‐renewal. Epidermal growth factor (EGF) and fibroblast growth factor‐2 enhanced GBM BTSC survival, proliferation, and subsequent sphere size. Blockade of EGF receptor (EGFR) signaling reduced exogenous mitogen‐independent GBM sphere growth. Implantation of as few as 10 exogenous mitogen‐independent GBM BTSCs led to the formation of highly invasive intracranial tumors, which closely resembled human GBMs, in immunocompromised mice. These results demonstrate that exogenous mitogen independence, mediated in part through EGFR signaling, is one characteristic that distinguishes CD133+ and CD133− GBM BTSCs from neural stem cells. This novel experimental system will permit the elucidation of additional constitutively activated mechanisms that promote GBM BTSC survival, self‐renewal, and proliferation. STEM CELLS 2009;27:1722–1733

Prophylactic anticonvulsants in patients with brain tumour.

OBJECTIVE We conducted a clinical trial to determine if prophylactic anticonvulsants in brain tumour patients (without prior seizures) reduced seizure frequency. We stopped accrual at 100 patients on the basis of the interim analysis. METHODS One hundred newly diagnosed brain tumour patients received anticonvulsants (AC Group) or not (No AC Group) in this prospective randomized unblinded study. Sixty patients had metastatic, and 40 had primary brain tumours. Forty-six (46%) patients were randomized to the AC Group and 54 (54%) to the No AC Group. Median follow-up was 5.44 months (range 0.13-30.1 months). RESULTS Seizures occurred in 26 (26%) patients, eleven in the AC Group and 15 in the No AC Group. Seizure-free survivals were not different; at three months 87% of the AC Group and 90% of the No AC Group were seizure-free (log rank test, p = 0.98). Seventy patients died (unrelated to seizures) and survival rates were equivalent in both groups (median survival = 6.8 months versus 5.6 months, respectively; log rank test, p = 0.50). We then terminated accrual at 100 patients because seizure and survival rates were much lower than expected; we would need > or = 900 patients to have a suitably powered study. CONCLUSIONS These data should be used by individuals contemplating a clinical trial to determine if prophylactic anticonvulsants are effective in subsets of brain tumour patients (e.g. only anaplastic astrocytomas). When taken together with the results of a similar randomized trial, prophylactic anticonvulsants are unlikely to be effective or useful in brain tumour patients who have not had a seizure.

Efficacy of Systemically Administered Oncolytic Vaccinia Virotherapy for Malignant Gliomas Is Enhanced by Combination Therapy with Rapamycin or Cyclophosphamide

Purpose: The oncolytic effects of a systemically delivered, replicating, double-deleted vaccinia virus has been previously shown for the treatment of many cancers, including colon, ovarian, and others. The purpose of this study was to investigate the oncolytic potential of double-deleted vaccinia virus alone or in combination with rapamycin or cyclophosphamide to treat malignant gliomas in vitro and in vivo. Experimental Design: Rat (RG2, F98, C6) and human (A172, U87MG, U118) glioma cell lines were cultured in vitro and treated with live or UV-inactivated vaccinia virus. Viral gene [enhanced green fluorescent protein (EGFP)] expression by fluorescence-activated cell sorting, relative cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and assays for cytopathic effects were examined. S.c. murine tumor xenografts (U87MG, U118, C6) and i.c. (RG2, F98) tumor models in immunocompetent rats were treated with systemic administration of EGFP-expressing vaccinia virus (vvDD-EGFP), alone or in combination with rapamycin or cyclophosphamide, or controls. Tumor size, viral biodistribution, and animal survival were assessed. Lastly, the oncolytic effects of vvDD-EGFP on human malignant glioma explants were evaluated. Results: vvDD-EGFP was able to infect and kill glioma cells in vitro. A single systemic dose of vvDD-EGFP significantly inhibited the growth of xenografts in athymic mice. Systemic delivery of vvDD-EGFP alone was able to target solitary and multifocal i.c. tumors and prolong survival of immunocompetent rats, whereas combination therapy with rapamycin or cyclophosphamide enhanced viral replication and further prolonged survival. Finally, vvDD-EGFP was able to infect and kill ex vivo primary human malignant gliomas. Conclusions: These results suggest that vvDD-EGFP is a promising novel agent for human malignant glioma therapy, and in combination with immunosuppressive agents, may lead to prolonged survival from this disease.