Treatment of recurrent malignant glioma with G207, a genetically engineered herpes simplex virus-1, followed by irradiation: Phase I study results

2042

Background: G207 is a doubly mutated (deletion of both γ134.5 loci, insertional inactivation of UL39) herpes simplex virus (HSV)-1. Safety and efficacy of intracerebral inoculations of G207 to patients suffering from recurrent malignant gliomas have been demonstrated in previous clinical trials. Methods: In this phase I clinical trial, a total of 1 x 109 plaque forming units (pfu) G207 were administered by five stereotactic injections of 0.2 mL each into regions of recurrent malignant glioma defined by MRI, followed by focal radiation therapy 24 hours post injection. Included patients suffered from inoperable pathologically proven recurrent glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA) which was progressive despite radiotherapy or chemotherapy and failed external beam radiotherapy > 5 Gray prior to study enrolment. Results: 9 patients were treated in this phase I study. 5 patients were suffering from relapsed GBM, 4 patients were suffering from relapsed AA. 1 month after treatment, 3 patients (3xGBM) showed SD, 2 patients (1xGBM, 1xAA) PR, and 4 patients (1xGBM, 3xAA) PD. The 2 patients with initial PR (1xGBM, 1xAA) were re-treated with G207/Irradiation at time point of tumor recurrence, showing PR one month after re-treatment again. Median overall survival time for all 9 patients was 229 days (7.6 months), with one patient still alive at time of abstract submission. In patients suffering from relapsed GBM, mOS was 7.4 months, in patients suffering from relapsed AA, mOS was 9.25 months. 20 serious adverse events occurred in this study, only 3 were possible/probable related to G207/irradiation. Within persistent areas of tumor, HSV staining was present by using a polyclonal antibody for HSV, indicating intratumoral G207 replication (proof of concept). Conclusions: In 9 patients suffering from relapsed GBM or AA, stereotactic intracerebral G207 inoculation followed by radiation therapy was feasible, safe, and induced clinically relevant responses. G207/Irradiation re-treatment was possible and induced anew clinical responses. Median overall survival is superior to published data in this patient population. Therefore, further clinical development of G207 in GBM is medically reasonable.

[Table: see text]

Enhanced antiglioma activity of chimeric HCMV/HSV-1 oncolytic viruses

Oncolytic herpes simplex virus (HSV)-1 gamma(1)34.5-deletion mutants (Deltagamma(1)34.5 HSV) are promising agents for tumor therapy. The attenuating mutation renders the virus aneurovirulent but also limits late viral protein synthesis and efficient replication in many tumors. We tested whether one function of gamma(1)34.5 gene, which mediates late viral protein synthesis through host protein kinase R (PKR) antiviral response evasion, could be restored, without restoring the neurovirulence. We have previously reported the construction of two chimeric Deltagamma(1)34.5 HSV vectors (chimeric HSV), C130 and C134, which express the human cytomegalovirus (HCMV) PKR-evasion genes TRS1 and IRS1, respectively. We now demonstrate the following. The HCMV/HSV-1 chimeric viruses (i) maintain late viral protein synthesis in the human malignant glioma cells tested (D54-MG, U87-MG and U251-MG); (ii) replicate to higher titers than Deltagamma(1)34.5 HSV in malignant glioma cells in vitro and in vivo; (iii) are aneurovirulent; and (iv) are superior to other Deltagamma(1)34.5 HSV with both improved reduction of tumor volumes in vivo, and improved survival in two experimental murine brain tumor models. These findings demonstrate that transfer of HCMV IRS1 or TRS1 gene into Deltagamma(1)34.5 HSV significantly improves replication in malignant gliomas without restoring wild-type neurovirulence, resulting in enhanced tumor reduction and prolonged survival.

Engineered herpes simplex virus expressing bacterial cytosine deaminase for experimental therapy of brain tumors

Lack of effective therapy of primary brain tumors has promoted the development of novel experimental approaches utilizing oncolytic viruses combined with gene therapy. Towards this end, we have assessed a conditionally replication-competent, gamma(1)34.5-deleted herpes simplex virus type 1 (HSV-1) expressing cytosine deaminase (CD) for treatment of malignant brain tumors. Our results are summarized as follows: (i) a recombinant HSV (M012) was constructed in which both copies of the gamma(1)34.5 gene were replaced with the bacterial CD gene, under the control of the cellular promoter Egr-1; (ii) M012-infected cells in vitro efficiently convert 5-fluorocytosine (5-FC) to 5-fluorouracil, thereby enhancing cytotoxicity of neighboring, uninfected cells; (iii) both direct and bystander cytotoxicity of murine neuroblastoma and human glioma cell lines after infection with M012 were demonstrated; (iv) direct intracerebral inoculation of A/J mice demonstrated lack of neurotoxicity at doses similar to G207, a gamma(1)34.5-deleted HSV with demonstrated safety in human patient trials and (v) intratumoral injection of M012 into Neuro-2a flank tumors in combination with 5-FC administration significantly reduced tumor growth versus tumors treated with R3659 combined with 5-FC, or treated with M012 alone. Thus, M012 is a promising new oncolytic HSV vector with an enhanced prodrug-mediated, antineoplastic effect that is safe for intracranial administration.

Genetically engineered human herpes simplex virus in the treatment of brain tumours

Central nervous system malignancies--particularly glioblastoma multiforme--pose significant problems for the development of novel therapeutics. In the absence of advances with standard surgical and chemotherapeutic approaches, the utilization of genetically engineered viruses--both as direct oncolytic agents (virus therapy) and for the delivery of foreign proteins (gene therapy)--represents a significant advance in the experimental approach to the management of patients with incurable tumours. Among other viruses, herpes simplex virus (HSV) offers an opportunity to influence the replication of tumour cells directly within the central nervous system. The propensity for HSV to replicate in tumour cells, and its large coding capacity, provide an experimental model for the development of novel therapeutics. The status of these experimental approaches and Phase I studies are summarized.

Casein kinase II phosphorylation of the human papillomavirus-18 E7 protein is critical for promoting S-phase entry

The human papillomavirus type 18 E7 protein subverts the pRb/E2F pathway to promote S-phase reentry by postmitotic, differentiated primary human keratinocytes in support of viral DNA amplification. We prepared a panel of HPV-18 E7 mutations in pRb binding or in casein kinase II (CKII) phosphorylation. Our results showed that the ability of E7 binding to pRb correlated with the activation of DNA polymerase alpha or cyclin E to various extents in differentiated keratinocytes of organotypic cultures but was insufficient to induce the proliferating cell nuclear antigen. Proteins mutated in the CKII recognition sequence or in one or both serine substrates (S32 and S34) bound pRb in vitro, but only those with negative charges at these two residues induced proliferating cell nuclear antigen effectively. Nevertheless, unscheduled cellular DNA synthesis occurred very inefficiently relative to the wild-type E7, if at all. Thus, both pRb binding and CKII phosphorylation of E7 are critical for activating cellular genes essential for S-phase entry.

Engineered herpes simplex virus expressing IL-12 in the treatment of experimental murine brain tumors

Genetically engineered, neuroattenuated herpes simplex viruses (HSVs) expressing various cytokines can improve survival when used in the treatment of experimental brain tumors. These attenuated viruses have both copies of gamma(1)34.5 deleted. Recently, we demonstrated increased survival of C57BL/6 mice bearing syngeneic GL-261 gliomas when treated with an engineered HSV expressing IL-4, as compared with treatment with the parent construct (gamma(1)34. 5(-)) alone or with a virus expressing IL-10. Herein, we report construction of a conditionally replication-competent mutant expressing both subunits of mIL-12 (M002) and its evaluation in a syngeneic neuroblastoma murine model. IL-12 induces a helper T cell subset type 1 response, which may induce more durable antitumor effects. In vitro studies showed that, when infected with M002, both Vero cells and murine Neuro-2a neuroblastoma cells produced physiologically relevant levels of IL-12 heterodimers, as determined by ELISA. M002 was cytotoxic for Neuro-2a cells and human glioma cell lines U251MG and D54MG. Neurotoxicity studies, as defined by plaque-forming units/LD(50), performed in HSV-1-sensitive A/J strain mice found that M002 was not toxic even at high doses. When evaluated in an intracranial syngeneic neuroblastoma murine model, median survival of M002-treated animals was significantly longer than the median survival of animals treated with R3659, the parent gamma(1)34.5(-) mutant lacking any cytokine gene insert. Immunohistochemical analysis of M002-treated tumors identified a pronounced influx of CD4(+) T cells and macrophages as well as CD8(+) cells when compared with an analysis of R3659-treated tumors. We conclude that M002 produced a survival benefit via oncolytic effects combined with immunologic effects meditated by helper T cells of subset type 1.

Viral E6-E7 transcription in the basal layer of organotypic cultures without apparent p21cip1 protein precedes immortalization of human papillomavirus type 16- and 18-transfected human keratinocytes

Organotypic cultures of human keratinocytes provide a useful model system to study human papillomavirus (HPV)-host cell interactions. In this study, we analyzed organotypic cultures of two HPV type 16 (HPV16) (FK16A and FK16B)- and two HPV18 (FK18A and FK18B)-transfected keratinocyte cell lines through the process of immortalization in vitro. For FK16A and FK18B cells, passages of both mortal cells in their extended life span and subsequent immortal stages were studied. Mortal cells of FK16A and FK18B showed a morphology reminiscent of mild to moderate dysplasia, whereas in their immortal descendants, severely dysplastic features were observed. Immortal FK18A cells were mildly to moderately dysplastic, while FK16B cells were severely dysplastic. The increasing degrees of dysplasia were associated with a decreasing expression of differentiation markers cytokeratin 10 and profilaggrin. All raft cultures expressed E6-E7 mRNAs in the basal layer, while the amount of viral transcripts in the suprabasal cells was in general proportional to the degree of dysplasia. In all cases, E6-E7 transcription and dysplastic features were highly correlated with cellular proliferation, as assessed by Ki-67 (MIB-1) antigen expression. Moreover, high levels of E6-E7 transcription and expression of p21cip1 protein in the basal layer seemed to be mutually exclusive. We conclude that expression of E6-E7 in the basal cells associated with increased proliferation in the absence of detectable p21cip1 protein is apparently necessary but not sufficient for immortalization, or for the loss of terminal differentiation, for which yet to be discovered additional events are required. The model system described in this study provides a valuable tool to analyze alterations in viral transcription regulation during HPV-mediated cell transformation.

Mutational analyses of differentiation-dependent human papillomavirus type 18 enhancer elements in epithelial raft cultures of neonatal foreskin keratinocytes

Human papillomaviruses (HPVs) reproduce only in differentiated squamous epithelia. Viral transcription is rather restricted in basal strata but increases dramatically in the spinous cells. Inopportune viral oncoprotein expression in the basal reserve cells can lead to dysplasias and carcinomas. Until now all studies to identify transcription factor binding sites within the upstream regulatory region (URR) that controls the expression of the oncogene have been conducted in proliferating cell cultures. We report the establishment of a reproducible and convenient system to examine cis elements important for differentiation-dependent transcriptional regulation. The bacterial lacZ gene under the control of the HPV URR-E6 promoter was transduced into primary human keratinocytes from neonatal foreskin by using high titer recombinant retroviruses. Acutely infected PHKs were then grown into stratified and differentiated epithelium on collagen rafts. lacZ expression was almost entirely restricted to the spinous cells, indicating that promoter activity was differentiation dependent, as seen in vivo. Using this system, we initiated a mutational analysis of previously identified promoter and enhancer elements within the HPV-18 URR. Three categories of mutation were observed: those that caused severe, moderate, or very small reduction in lacZ expressions. The results show both similarities and differences to previously published and present studies in proliferating primary human keratinocytes in monolayer cultures or in immortalized or transformed cell lines. This system is applicable to study both host and viral promoters that require squamous differentiation for their activity.

Transition of human papillomavirus type 16 and 18 transfected human foreskin keratinocytes towards immortality: activation of telomerase and allele losses at 3p, 10p, 11q and/or 18q

This study aimed at resolving cellular genetic alterations in the process of in vitro immortalization of human keratinocytes by human papillomavirus (HPV) types 16 and 18. Four cell lines of primary human foreskin keratinocytes transfected with HPV 16 and HPV 18, respectively, were analysed during the transition from the mortal to immortal state. All cell lines showed strong telomerase activity at the immortal state, whereas no or only weak telomerase activity was detected in mortal precursor cells. This was consistent with telomere stabilization or restoration only observed in immortal cells. HPV physical state and copy number appeared constant during immortalization and HPV E6/E7 transcripts were present throughout. Immortalization was associated with clonal allele losses at 3p combined with either 11q or 18q or at 10p, dependent on the cell line. Moreover, a correlation was evident between the onset of telomerase activity and allele loss at 3p or 10p. All immortalized cells retained the capability to differentiate after growth in the presence of physiological calcium and serum. Moreover, one of the immortal cell lines displayed terminal differentiation after organotypic culturing on collagen rafts. The data suggest that (a) several pathways exist for HPV mediated immortalization that may involve genes residing at 3p, 10p, 11q and/or 18q; (b) 3p and 10p may encode genes involved in telomerase regulation; and (c) immortalization in vitro can be correlated with a spectrum of morphological changes varying from mild to severe dysplasia.

Total condylar knee replacement. A study of factors influencing range of motion as late as two years after arthroplasty

The factors influencing the range of motion of the knee after total condylar knee replacement were analyzed in fifty-five consecutive patients who had seventy-one replacements and a minimum follow-up of two years. Statistically significant improvement in flexion occurred between the first postoperative evaluation in the hospital, the evaluation at discharge, and the evaluations at three months and one year after replacement. Postoperative range of motion was not influenced by the patient's gender, by the extent of the disease (monoarticular in comparison with polyarticular), or by treatment with a unilateral or bilateral procedure. The knees of patients with rheumatoid arthritis gained extension at the expense of flexion. The average flexion arcs of the knees with rheumatoid arthritis and of those with osteoarthritis were the same two years after operation as they had been preoperatively. Knees with preoperative flexion of more than 100 degrees had lost flexion at follow-up, whereas those with preoperative flexion of less than 100 degrees had gained flexion. Significant improvement in extension occurred only before discharge. For the patients whose preoperative flexion contracture was 10 degrees or more, virtually all improvement in the contracture occurred at the time of surgery. Patients who had a simultaneous bilateral total knee replacement did as well as those with a single knee replacement.(ABSTRACT TRUNCATED AT 250 WORDS)