Attenuated, replication-competent herpes simplex virus type 1 mutant G207: safety evaluation in mice

Herpes simplex virus type 1 (HSV-1) mutants that are attenuated for neurovirulence are being used for the treatment of cancer. We have examined the safety of G207, a multimutated replication-competent HSV-1 vector, in mice. BALB/c mice inoculated intracerebrally or intracerebroventricularly with 10(7) PFU of G207 survived for over 20 weeks with no apparent symptoms of disease. In contrast, over 80% of animals inoculated intracerebrally with 1.5 x 10(3) PFU of HSV-1 wild-type strain KOS and 50% of animals inoculated intracerebroventricularly with 10(4) PFU of wild-type strain F died within 10 days. Similarly, after intrahepatic inoculation of G207 (3 x 10(7) PFU) all animals survived for over 10 weeks, whereas no animals survived for even 1 week after inoculation with 10(6) PFU of KOS. After intracerebroventricular inoculation, LacZ expression was initially observed in the cells lining the ventricles and subarachnoid space; expression decreased until almost absent within 5 days postinfection, with no apparent loss of ependymal cells. G207 DNA could be detected by PCR in the brains of mice 8 weeks after intracerebral inoculation; however, no infectious virus could be detected after 2 days. As a model for latent HSV in the brain, we used survivors of an intracerebral inoculation of HSV-1 KOS at the 50% lethal dose. Inoculation of a high dose of G207 at the same stereotactic coordinates did not result in reactivation of detectable infectious virus or symptoms of disease. We conclude that G207 is safe at or above doses that were efficacious in mouse tumor studies.

Influence of renal function on the pharmacokinetics of cerivastatin in normocholesterolemic adults

OBJECTIVE

The influence of impaired renal function on the pharmacokinetics of single and multiple doses of cerivastatin was evaluated in this nonrandomized, non-blinded, 7-day, multiple-dose study.

METHODS

Thirty-five adults between the ages of 21 years and 75 years with normal renal function (CL(CR) >90 ml/min/1.73 m2, n = 9), or patients with either mild (CL(CR) 61 ml/min/1.73 m2 to < or =90 ml/min/1.73 m2, n = 9), moderate (CL(CR) 30 ml/min/1.73 m2 to < or =60 ml/ min/1.73 m2, n = 8), or severe (CL(CR) <30 ml/min/ 1.73 m2, but not on dialysis, n = 9) renal impairment were given cerivastatin 0.3 mg daily each evening for 7 days. The steady-state pharmacokinetics of cerivastatin, including the area under the concentration-time curve (AUC)0-24, peak plasma concentration (Cmax), time to reach Cmax (tmax) and elimination half-life (t1/2), were determined on day 1 and day 7. The logarithm of the pharmacokinetic variables was analyzed using analysis of variance (ANOVA). Safety assessments included physical examination, fundoscopy, vital signs, electrocardiogram (ECG), adverse events, and laboratory safety indices.

RESULTS

The day-1 AUC in patients with mild renal impairment was similar to that of patients with normal function (19.6 microg/h/l vs 19.2 microg/h/l, respectively). However, the AUC for cerivastatin patients with moderate or severe renal impairment was 40-60% higher (30.8 microg/h/l and 29.0 microg/h/l, respectively). Cmax values for patients with normal, mild, moderate, and severe renal impairment were 3.3, 3.4, 4.6, and 5.2 microg/l, respectively. This modest increase in plasma cerivastatin levels is nearly equivalent to a 0.4-mg daily dose, which has been recently approved in the United States. The mean t1/2 of cerivastatin was less than 4.5 h in all patients, indicating that renal dysfunction did not promote cerivastatin accumulation. This observation was confirmed by the finding that the cerivastatin plasma levels on day 1 and day 7 were similar in all patient groups. Furthermore, the mean AUC and Cmax values for both demethylated and hydroxylated cerivastatin were similar in the patients with the most severe renal dysfunction to the corresponding values in healthy subjects. Cerivastatin was well tolerated in all patients irrespective of renal function. Adverse events were observed in 37% of the subjects; nearly all were mild and generally of short duration, and most resolved without intervention. Incidence of adverse events was similar across all three renal groups and the control group. There were no clinically significant laboratory changes other than those consistent with renal disease.

CONCLUSION

This study demonstrates that dosage adjustment of the daily 0.3-mg cerivastatin dose in patients with significant renal impairment is likely unnecessary.

Systemic antitumor immunity in experimental brain tumor therapy using a multimutated, replication-competent herpes simplex virus

Replication-competent, attenuated herpes simplex virus (HSV) vectors have been developed for viral oncolytic therapy of primary and metastatic malignant brain tumors. However, the role of the host immune responses in the brain has not been elucidated. N18 neuroblastoma cells were used as a tumor model in syngeneic A/J mice to test the therapeutic efficacy of G207, a conditionally replicating HSV vector, in an immunocompetent condition. G207 inoculated intraneoplastically exhibited a prominent oncolytic antitumor effect in mice harboring N18 tumors in the brain or subcutaneously, and, in addition, elicited a systemic antitumor immune response. Subcutaneous tumor therapy with G207 caused regression of a remote, established tumor in the brain or in the periphery, which was potentially mediated by the systemic antitumor immune response, and provided persistent tumor-specific protection against N18 tumor rechallenge in the brain as well as in the periphery. Antitumor immunity was associated with an elevation of specific CTL activity against N18 tumor cells that persisted for at least 13 months. The results suggest that the oncolytic antitumor action of replication-competent HSV may be augmented by induction of specific and systemic antitumor immunity effective both in the periphery and in the brain.

Effect of prior exposure to herpes simplex virus 1 on viral vector-mediated tumor therapy in immunocompetent mice

Replication-competent, attenuated mutants of herpes simplex virus type 1 (HSV-1) have been shown to be efficacious for tumor therapy. However, these studies did not address the consequences of prior exposure to HSV, as will be the case with many patients likely to receive this therapy. Two strains of mice, A/J and BALB/c, were infected with wild-type HSV-1 by intraperitoneal injection and the immune response was determined by plaque reduction assay for neutralizing antibody and ELISA for IgG and IgM. Syngeneic tumors, N18 neuroblastoma and CT26 colon carcinoma, were implanted subcutaneously in HSV-1 seropositive and naive A/J and BALB/c mice, respectively. Established tumors were subsequently treated intratumorally with a multi-mutated HSV-1, G207. G207 inhibited tumor growth to a similar extent whether the mice were seropositive or not. We next examined the effect of multiple intratumoral inoculations of a 10-fold lower dose of G207 on tumor growth. In the multiple treatment group (biweekly for 3 weeks), 75% of tumors were cured, whereas no cures were seen in the single treatment group. We conclude that HSV seropositivity should not deleteriously affect the efficacy of G207 tumor therapy, and multiple inoculations of virus should be considered for clinical evaluation.

Local and systemic therapy of human prostate adenocarcinoma with the conditionally replicating herpes simplex virus vector G207

Prostate adenocarcinoma is the most common nonskin malignancy in males and the second most common cause of cancer death in the United States (Landis et al., 1998). Initial treatments of surgery or radiotherapy may cause impotence and/or incontinence from neural damage (Eastham and Scardino, 1998; Porter et al., 1998). When extraprostatic or metastatic disease develops, castration or pharmaceutical androgen ablation is utilized (Catalona, 1994). Androgen-resistant recurrence indicates a poor prognosis and justifies experimental chemotherapy (Oh and Kantoff, 1998). G207 (Mineta et al., 1995; Yazaki et al., 1995) is a multimutated herpes simplex virus 1 (HSV) vector that replicates within cancer cells, causing cellular death; however, replication is limited in normal cells, including those of the nervous system. In vitro, G207 at a low multiplicity of infection (MOI of 0.01) is oncolytic for multiple human prostate cancer cells. In athymic mice, a single intraneoplastic inoculation of G207 completely eradicates >22% of established subcutaneous human prostate cancer tumors irrespective of hormonal responsiveness. Two intraneoplastic inoculations of G207 completely eradicated two of three recurrent previously irradiated tumors and two intravenous administration of G207 induced tumor regression in distant subcutaneous tumors and completely eradicated one-fourth of the tumors.

Modification of immune response by low dose ionizing radiation: role of apoptosis

Acute as well as fractionated whole body exposures to low doses (< 50 cGy) of ionizing radiation (LDR) have been reported to alter several immunological parameters in experimental animals. It is, however, not clear whether the augmentation of immune response by LDR will be observed for all responses and across genetic barriers. Since several proteins including p53 are synthesized following radiation exposure, the role of p53 and consequently that of activation induced apoptosis in the immunomodulation by LDR also remained to be evaluated. Experiments were, therefore, carried out in two different strains of inbred mice viz. C57BL/6 and BALB/c, exposed to fractionated LDR (4 cGy/day, 5 days/week, total dose 20 cGy) and subsequently stimulated with the polyclonal mitogen Con A or immunized with Mycobacterium vaccae or dinitrofluorobenzene (DNFB) for delayed type hypersensitivity (DTH) response. The proliferation of spleen cells in response to con A as measured by [3H]thymidine incorporation was significantly higher in 20 cGy-irradiated C57BL/6 mice as compared with that in the Con A-stimulated cells from sham-irradiated controls. The same response was suppressed by LDR in BALB/c mice. On the other hand, DTH to M. vaccae as well as DNFB was suppressed in C57BL/6 mice while DTH to M. vaccae was augmented in BALB/c mice and that to DNFB was not significantly affected following same dose. The augmentation of response to con A in C57BL/6 mice was prominent in CD4- (CD8+) T cells and was marked by the decrease in the proportion of cells expressing p53 as estimated by flow cytometry. Reduction in expression of p53 was accompanied by reduced apoptosis, as measured by TUNEL assay, in the Con A-stimulated spleen cells of irradiated C57BL/6 mice when compared with that in the sham-treated controls. The spleen cells of BALB/c mice showed exactly opposite profiles in this respect. Thus alteration in the immune response following LDR depends on antigen, type of response as well as the strain of mice used. Furthermore, the alterations in the expression of pro-apoptosis gene p53 and activation induced apoptosis in the effector or regulatory cells seem to contribute to the end result.

Hepatoma-specific antitumor activity of an albumin enhancer/promoter regulated herpes simplex virus in vivo

Targeting viral vectors to appropriate cell types so that normal cells are not adversely affected is an important goal for gene therapy. Previously, we described a novel approach to viral gene therapy using a conditional, replication-competent herpes simplex virus (HSV), where replication and associated cytotoxicity are limited to a specific cell-type by the regulated expression of an essential immediate-early viral gene product. In this report we analyze the hepatoma-specific replication, cytotoxicity and anti-tumor effect of recombinant HSV G92A, regulated by the albumin enhancer/promoter. G92A efficiently replicated in vitro in two human hepatoma cell lines expressing albumin, but not in four human non-hepatoma, albumin-non-expressing tumor cell lines, while all cell lines were equally susceptible to a tissue nonspecific HSV recombinant, hrR3. In vivo, G92A replicated well in subcutaneous xenografts of human hepatoma cells (Hep3B) in athymic mice, but not in non-hepatoma subcutaneous tumors (PC3 and HeLa), whereas, hrR3 replicated well in both tumor types. Intratumoral inoculation of G92A inhibited the growth of established subcutaneous hepatoma tumors in nude mice, but not prostate tumors. Replication-competent viral vectors controlled by cell-specific transcriptional regulatory sequences provide a new therapeutic strategy for tumor therapy.

In vivo immune evasion mediated by the herpes simplex virus type 1 immunoglobulin G Fc receptor

Herpes simplex virus (HSV) glycoproteins gE and gI form an immunoglobulin G (IgG) Fc receptor (FcgammaR) that binds the Fc domain of human anti-HSV IgG and inhibits Fc-mediated immune functions in vitro. gE or gI deletion mutant viruses are avirulent, probably because gE and gI are also involved in cell-to-cell spread. In an effort to modify FcgammaR activity without affecting other gE functions, we constructed a mutant virus, NS-gE339, that has four amino acids inserted into gE within the domain homologous to mammalian IgG FcgammaRs. NS-gE339 expresses gE and gI, is FcgammaR-, and does not participate in antibody bipolar bridging since it does not block activities mediated by the Fc domain of anti-HSV IgG. In vivo studies were performed with mice because the HSV-1 FcgammaR does not bind murine IgG; therefore, the absence of an FcgammaR should not affect virulence in mice. NS-gE339 causes disease at the skin inoculation site comparably to wild-type and rescued viruses, indicating that the FcgammaR- mutant virus is pathogenic in animals. Mice were passively immunized with human anti-HSV IgG and then infected with mutant or wild-type virus. We postulated that the HSV-1 FcgammaR should protect wild-type virus from antibody attack. Human anti-HSV IgG greatly reduced viral titers and disease severity in NS-gE339-infected animals while having little effect on wild-type or rescued virus. We conclude that the HSV-1 FcgammaR enables the virus to evade antibody attack in vivo, which likely explains why antibodies are relatively ineffective against HSV infection.

Acute effects of oral glibenclamide on blood pressure and forearm vascular resistance in diabetics

1. To determine the effects of an acute oral dose of glibenclamide on blood pressure (BP), basal forearm vascular resistance (FVR) and FVR responses to the K+(ATP) channel activating vasodilator diazoxide, a placebo-controlled, double-blind cross-over study was performed in eight male volunteers with non-insulin-dependent diabetes mellitus. 2. Changes in vascular responses to progressively increasing concentrations of diazoxide (3.75-30 mg/kg per min) and noradrenaline (25-100 ng/kg per min) were measured by venous occlusion plethysmography. 3. Glibenclamide significantly lowered plasma glucose levels compared with placebo (P < 0.02) and attenuated the decrease in FVR (P < 0.05) and the decrease in systolic BP (P < 0.05) that followed a meal. However, vasodilator responses to diazoxide were potentiated by the administration of oral glibenclamide (P < 0.01). 4. Acute administration of oral glibenclamide attenuates the normal decrease in FVR and systolic BP that follows a meal and potentiates rather than inhibits forearm vasodilator responses to intra-arterial diazoxide, probably via indirect humoral effects. These results suggest that glibenclamide has direct or indirect vasoconstrictor effects that antagonize the normal increase in forearm blood flow that follows a meal and that the inhibition of vascular K+(ATP) channels following acute oral glibenclamide administration is clinically insignificant compared with other indirect vascular effects of the drug.

The herpes simplex virus-1 glycoprotein E (gE) mediates IgG binding and cell-to-cell spread through distinct gE domains

Herpes simplex virus-1 (HSV-1) glycoprotein E (gE) is a multifunctional protein capable of both binding the Fc portion of IgG and mediating cell-to-cell spread of HSV-1. Here we report that the domain on gE involved in IgG binding is distinct from the domain involved in mediating cell-to-cell spread. To do this we have used five mutants of the HSV-1 strain NS: NS-gE(null), a gE deletion virus; rNS-gE(null), a gE rescued virus; NS-gE339, a gE mutant virus with a four amino acid insert at position 339; rNS-gE339, a gE rescue of NS-gE339; and NS-gE406, a gE mutant virus with the same four amino acids inserted at position 406. Using IgG coated sheep red blood cells in rosetting assays, we show that the NS-gE339 does not bind IgG, yet retains the ability to mediate normal cell-to-cell spread. These results demonstrate that the gE domain involved in IgG binding differs from the domain involved in cell-to-cell spread.

Comparative effects of glibenclamide and metformin on ambulatory blood pressure and cardiovascular reactivity in NIDDM

OBJECTIVE

To compare the effects of chronic glibenclamide and metformin therapy on blood pressure (BP) and cardiovascular responsiveness in patients with NIDDM.

RESEARCH DESIGN AND METHODS

Fourteen patients with NIDDM received metformin or glibenclamide for 1 month in a double-blind, randomized crossover study. At the end of each treatment period, patients were tested for forearm vascular responsiveness to intrabrachial arterial infusion of diazoxide (an ATP-sensitive potassium channel opener), acetylcholine, sodium nitroprusside, and norepinephrine, BP responses to intravenous infusions of NE and angiotensin II, BP responses to cold pressor testing and isometric exercise, and 24-h ambulatory BP monitoring.

RESULTS

Metformin and glibenclamide produced similar glycemic control. Mean 24-h BPs did not differ between the two groups, but mean 24-h heart rates were significantly lower (75 +/- 6 bpm vs. 80 +/- 6 bpm) on glibenclamide therapy than on metformin. Plasma norepinephrine levels were significantly higher on glibenclamide (6.41 +/- 1.77 vs. 4.26 +/- 1.54 mmol/l, P < 0.01), and systolic BP responses to intravenous norepinephrine and angiotensin II were significantly higher on glibenclamide than on metformin (P < 0.02 and P < 0.05, respectively). Systolic BP responses to cold pressor testing appeared higher on glibenclamide than on metformin, but the difference did not quite achieve statistical significance (P = 0.052). Baseline forearm vascular resistance did not differ between the two drugs, nor did forearm vascular resistance responses to diazoxide, acetylcholine, sodium nitroprusside, and norepinephrine differ.

CONCLUSIONS

Glibenclamide therapy is accompanied by greater systolic BP responses to norepinephrine and angiotensin II and higher plasma norepinephrine levels than those that occur on metformin therapy. Lower heart rates on glibenclamide therapy despite evidence of greater sympathetic activity suggests that glibenclamide may have negative chronotropic effects.

Acute effects of oral glibenclamide on blood pressure and forearm vascular resistance in diabetics

1. To determine the effects of an acute oral dose of glibenclamide on blood pressure (BP), basal forearm vascular resistance (FVR) and FVR responses to the K+ATP channel activating vasodilator diazoxide, a placebo-controlled, double-blind cross-over study was performed in eight male volunteers with non-insulin-dependent diabetes mellitus. 2. Changes in vascular responses to progressively increasing concentrations of diazoxide (3.75-30 mg/kg per min) and noradrenaline (25-100 ng/kg per min) were measured by venous occlusion plethysmography. 3. Glibenclamide significantly lowered plasma glucose levels compared with placebo (P < 0.02) and attenuated the decrease in FVR (P < 0.05) and the decrease in systolic BP (P < 0.05) that followed a meal. However, vasodilator responses to diazoxide were potentiated by the administration of oral glibenclamide (P < 0.01). 4. Acute administration of oral glibenclamide attenuates the normal decrease in FVR and systolic BP that follows a meal and potentiates rather than inhibits forearm vasodilator responses to intra-arterial diazoxide, probably via indirect humoral effects. These results suggest that glibenclamide has direct or indirect vasoconstrictor effects that antagonize the normal increase in forearm blood flow that follows a meal and that the inhibition of vascular K+ATP channels following acute oral glibenclamide administration is clinically insignificant compared with other indirect vascular effects of the drug.

Cardiovascular effects of oral hypoglycaemic drugs

1. There is increasing evidence that sulfonylurea and biguanide oral hypoglycaemic drugs have cardiovascular effects and influence risk factors for cardiovascular disease in patients with non-insulin-dependent diabetes because of actions that are unrelated to alterations in glycaemic control. 2. While sulfonylureas may have anti-arrhythmic effects following myocardial ischaemia, there is concern that their action on vascular ATP-sensitive potassium channels may contribute to elevated blood pressure and enhanced vascular responsiveness. 3. In contrast to sulfonylureas, metformin (a biguanide) appears to reduce blood pressure and have beneficial effects on plasma lipoproteins by reducing low-density lipoprotein cholesterol and possibly increasing high-density lipoprotein cholesterol levels. 4. The pharmacological basis and clinical significance of these effects of sulfonylureas and biguanides require further investigation.

Electrokinetic behaviour of subpopulations of T lymphocytes in allografted mice

In AKR(H-2k) mice transplanted with DBA/2(H-2d) skin grafts, the mean electrophoretic mobilities (EPM) of total lymph node cells (LNC) and T cells were significantly reduced. Subpopulations of T lymphocytes, viz. CD4- (CD8- (CD4+) T cells were obtained by depletion treatment of T cells with monoclonal antibodies specific for these surface antigens and complement. Determination of EPM of these two subpopulations revealed that the electrokinetic change following immunostimulation equally afflicted these two subpopulations. These data thus confirmed that CD4+ as well as CD8+ T cells were activated in MHC unmatched allograft rejection.

Seasonal relapses in affective disorder in the Tropics: a prospective follow-up of 12 patients

Seasonal relapses of affective disorder are known. We report 12 patients who had season-linked relapses during a prospective follow-up period of 4 years. There were both winter and summer relapses of mania and depression. The centre is in the tropical zone, with lesser variation of sunshine and temperature than in more extreme latitudes. This may inference the pattern of relapse in affective disorder. Differences in relapses between tropical and temperate zones need to be investigated.

Suppression of skin allograft rejection by post-transplantation administration of specific anti-lymphocyte serum

An heterologous anti-lymphocyte serum ALS(I-GR), was raised in rabbits by immunization with draining lymph node cells of AKR mice which had rejected DBA/2 skin allografts. Treatment of AKR mice with this ALS on the 4th day after DBA/2 skin grafting, significantly prolonged the survival of the graft in comparison with that in allografted mice treated with normal rabbit serum. In contrast, ALS prepared against unsensitized lymph node cells was found to be ineffective when administered after transplantation. A further prolongation of allograft survival was obtained when ALS(I-GR) was administered to recipients on days +4 and +7. ALS(I-GR) seemed to specifically suppress the rejection of DBA/2, but not of C57 BL/6 skin grafts. The suppressive action of ALS(I-GR) was not due to cross reactive (anti-DBA) antibodies and was probably directed against idiotypic determinants on antigen-stimulated cells.

Differential interaction of anti-lymphocyte serum with sub-populations of lymph node cells

Interaction of normal and Salmonella typhi `H'-sensitized rat lymph node cells with two different types of anti-lymphocyte serum (ALS) has been studied. One type of ALS, named as ALS(N), was prepared by immunizing rabbits with normal non-sensitized lymph node cells while the other, ALS(I), was produced by injecting rabbits with sensitized cells.

The histogram of electrophoretic mobilities (EPM) of ALS(N)-treated normal cells resolves into two Gaussian components corresponding to Class `A' and Class `B' cells respectively. ALS(N) brings about a significant reduction in the mean EPM of both these components indicating that ALS(N) binds to both the functional cell types with equal avidity. Analysis of the histogram of EPM of ALS(N)-treated sensitized cells reveals that ALS(N) leaves the mean EPM of antibody-producing Class `C' cells unchanged. ALS(I), on the other hand, is effective in binding to Class `C' cells in addition to the other cell types. These investigations thus demonstrate that ALS(N) has a differential action on the antigen-sensitive cells as compared to the antibody-producing cells. Further, this lack of interaction with Class `C' cells appears to be a result of a radically different surface-antigenic configuration of these cells.