MiR129-5p-loaded exosomes suppress seizure-associated neurodegeneration in status epilepticus model mice by inhibiting HMGB1/TLR4-mediated neuroinflammation

BACKGROUND

Neuroinflammation contributes to both epileptogenesis and the associated neurodegeneration, so regulation of inflammatory signaling is a potential strategy for suppressing epilepsy development and pathological progression. Exosomes are enriched in microRNAs (miRNAs), considered as vital communication tools between cells, which have been proven as potential therapeutic method for neurological disease. Here, we investigated the role of miR129-5p-loaded mesenchymal stem cell (MSC)-derived exosomes in status epilepticus (SE) mice model.

METHODS

Mice were divided into four groups: untreated control (CON group), kainic acid (KA)-induced SE groups (KA group), control exosome injection (KA + Exo-con group), miR129-5p-loaded exosome injection (KA + Exo-miR129-5p group). Hippocampal expression levels of miR129-5p, HMGB1, and TLR4 were compared among groups. Nissl and Fluoro-jade B staining were conducted to evaluate neuronal damage. In addition, immunofluorescence staining for IBA-1 and GFAP was performed to assess glial cell activation, and inflammatory factor content was determined by ELISA. Hippocampal neurogenesis was assessed by BrdU staining.

RESULTS

The expression of HMGB1 was increased after KA-induced SE and peaking at 48 h, while hippocampal miR129-5p expression decreased in SE mice. Exo-miR129-5p injection reversed KA-induced upregulation of hippocampal HMGB1 and TLR4, alleviated neuronal damage in the hippocampal CA3, reduced IBA-1 + and GFAP + staining intensity, suppressed SE-associated increases in inflammatory factors, and decreased BrdU + cell number in dentate gyrus.

CONCLUSIONS

Exosomes loaded with miR129-5p can protect neurons against SE-mediated degeneration by inhibiting the pro-inflammatory HMGB1/TLR4 signaling axis.

Characterization of the blastogenic response to LPS of bovine peripheral blood mononuclear cells

Mitogens are diverse compounds of plant and microbial origin, widely employed to test immunocompetence in animals. The blastogenic response of bovine Peripheral Blood Mononuclear Cells (PBMC) to lypopolysaccharides (LPS) has been investigated in our laboratories for a long time. In particular, a possible correlation between blastogenic response to LPS and disease resistance of periparturient dairy cows had been observed in previous studies. Most important, low responder cows presented a higher frequency of disease cases after calving, compared with high responder animals. Owing to the above, different aspects of the blastogenic response to LPS were investigated on PBMC of healthy Friesian cows, using a 72-hour Bromodeoxyuridin (BrDU) cell proliferation assay. Stimulation with LPS induced little if any replication of bovine PBMC over 72 hours despite consistent BrDU detection in all the PBMC samples under study. Poor replication of LPS-stimulated PBMC was confirmed by cell cycle and cell growth flow cytometry analyses. In particular, LPS stimulation gave rise to very low percentages of S phase cells, sometimes lower than in control, unstimulated cells, as opposed to Concanavalin A-stimulated PBMC. Magnetic separation and analysis of BrDU-treated bovine PBMC after exposure to LPS showed that both B and CD4 T cells are involved in the blastogenic response to LPS, in contrast with current data based on human and murine models. Finally, LPS caused an early, specific up-regulation of TNF-α and TLR4 genes in bovine PBMC, and significant correlations were shown between the expression of inflammatory cytokine and Indoleamine-pyrrole 2,3-dioxygenase (IDO1) genes. On the whole, our data indicate that differences in the blastogenic response to LPS could be partly accounted for by heterogenicity of responding cells (B and T lymphocytes), which might also have an impact on induction and regulation of inflammatory responses and endotoxin tolerance.

Repeated exposure to 5-bromo-2'-deoxyuridine causes decreased proliferation and low-grade inflammation in the lungs of mice

Incorporation of 5-bromo-2'-deoxyuridine (BrdU) into proliferating cells has been used to label dividing cells in many tissues. Although BrdU has been shown to be genotoxic, teratogenic and mutagenic, such adverse effects have largely been ignored by researchers. We determined whether long-term BrdU exposure causes any histopathological changes in the lungs of mice. Eight-week-old male C57/BL6J mice were administered BrdU by intraperitoneal injection on 3 consecutive days of each week for 14 weeks. While no obvious structural changes such as tissue damage, fibrosis, emphysema, airway remodeling, vascular thickening or tumorigenesis were noted, a moderate degree of macrophage infiltration was observed in the airways and lung parenchyma in the lungs of the mice exposed repeatedly to BrdU (BrdU-exposed mice). The proliferative activities of the airway and alveolar epithelial and mesenchymal cells were reduced in the BrdU-exposed mice, although the numbers of these cells in the lungs were maintained. Double immunofluorescence study of the lungs of the BrdU-exposed mice showed overexpression of IL-6 in the airway epithelial and alveolar wall cells, some of which were also double-positive for BrdU. These results indicate that long-term exposure to BrdU inhibits cell proliferation and induces low-grade inflammation in the lungs of mice. Our findings underscore the need for caution in the interpretation of studies that involve long-term exposure to BrdU.

Cumulative labeling of embryonic mouse neural retina with bromodeoxyuridine supplied by an osmotic minipump

I describe a method for providing cumulative label of bromodeoxyuridine (BrdU) to mouse embryos. Commercially available osmotic pumps, which release their contents at a steady rate, were implanted subcutaneously in the interscapular space of pregnant mice on embryonic day (E) 9.5-12.5. Survival times varied from 4h to 37 days. Tissues (embryonic and neonatal eyes and maternal intestine) were immunochemically labeled for BrdU and examined histologically. The first detectably labeled cells appeared 4-7h post-implantation (hpi) and all cycling cells were labeled for at least 7 days post-implantation (dpi). Retinal development appeared normal. Terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) stained retinas that had been exposed to BrdU showed no more apoptotic cells than those unexposed. I conclude that the maternally implanted osmotic pump successfully provides cumulative BrdU labeling in the mouse embryo.

Brivudin (Bromovinyl Deoxyuridine)

Brivudin is an oral thymidine analogue indicated for the early treatment of acute herpes zoster in immunocompetent adults. It has high, selective activity against varicella zoster virus (VZV), inhibiting VZV replication, possibly through competitive inhibition of viral DNA polymerase, or by acting as an alternative substrate to deoxythymidine triphosphate, causing viral DNA strand breakage. In a large, 7-day, phase III trial in immunocompetent patients with herpes zoster, once-daily brivudin 125mg was significantly more effective than oral acyclovir 800mg five times daily in reducing the mean time from start of treatment to last vesicular eruption, and was as effective as acyclovir at healing lesions and alleviating acute zoster-related pain. The likelihood of developing post-herpetic neuralgia (PHN) in immunocompetent patients aged > or =50 years was significantly lower with brivudin than with acyclovir. Brivudin was as effective as oral famciclovir 250mg three times daily in terms of the prevalence of PHN, the time to last vesicular eruption and lesion healing in another large, 7-day, phase III study in immunocompetent patients with herpes zoster. Oral brivudin is generally well tolerated, with a similar tolerability profile to those of oral acyclovir or famciclovir. Nausea was the most commonly reported adverse event.

Brivudin als alternative systemische Therapie zu Aciclovir und Ganciclovir bei akutem retinalen Nekrosesyndrom durch Varizella-Zoster-Virus

BACKGROUND

Two cases of acute retinal necrosis (ARN-) syndrome caused by an infection with varicella zoster virus (VZV) are demonstrated. VZV-DNA was detected in vitreous biopsies by polymerase-chain-reaction (PCR). The course of retinal necrosis was decisively improved by changing antiviral therapy from aciclovir and/or ganciclovir to brivudine.

MATERIAL AND METHODS

Patient 1: 51 years, male, initial visual acuity 20/40; patient 2: 17 years, female, initial visual acuity 20/30. Both patients were immunocompetent and presented with an unilateral acute retinal necrosis syndrome with peripheral chorioretinitis, retinal vasculitis, vitreous inflammation and optic disc swelling, which resulted in progressive visual loss in a few days.

RESULTS

In both patients VZV-DNA was detected in vitreous biopsies with PCR. A regression of intraocular inflammation and necrotic retinal foci was only observed after changing the initial systemic therapy from aciclovir (Zovirax) intravenously 1500 mg/day) and/or ganciclovir (Cymeven) intravenously 250 mg/day) to brivudine (Zostex) per os 500 mg/day). Vitreoretinal surgery was necessary in both patients because of rhegmatogenous retinal detachment. Visual acuity stabilised in patient 1 to 20/200 and in patient 2 to 20/25 during a follow-up of 16 or 32 months, respectively.

CONCLUSION

Brivudine represents an alternative therapy, if standard treatment with aciclovir and/or ganciclovir failed in cases of ARN-syndrome due to presumed drug-resistant varicella zoster virus-subtypes. Complete remission and preservation of a satisfactory function can be achieved.

Primary central nervous system lymphoma: Phase I evaluation of infusional bromodeoxyuridine with whole brain accelerated fractionation radiation therapy after chemotherapy

BACKGROUND

The current study was performed to determine the maximum tolerated dose (MTD), toxicity, and outcome of infusional 5 bromo-2'-deoxyuridine (bromodeoxyuridine; BUdR) given with accelerated fractionation whole brain radiation therapy (WBRT) after chemotherapy for the treatment of primary central nervous system lymphoma (PCNSL).

METHODS

Twelve patients with untreated and histologically confirmed PCNSL were entered on the study between 1994 and 1996. Chemotherapy was comprised of one course of IDHAP plus high-dose methotrexate (HD-MTX). IDHAP is comprised of idarubicin at a dose of 1.5 mg/m(2)/day x 4 days intravenously by continuous infusion (i.v. CI), dexamethasone at a dose of 40 mg i.v. on Days 1-5, cytosine arabinoside at a dose of 2000 mg/ m(2) i.v. on Day 5 after cisplatin, and cisplatin at a dose of 25 mg/m(2)/day x 4 days i.v. CI. HD-MTX was given at a dose of 3.5 g/m(2) i.v. between Day 10 and Day 14 after IDHAP. BUdR was given as an i.v. CI over 48 hours, 2-3 days prior to WBRT and then weekly during WBRT. Dose escalation started at 1.5 g/m(2)/day for Cohort 1 with subsequent increments of 0.3 g/m(2)/day. The WBRT dose was 45 grays (Gy) at a dose of 1.5 Gy twice a day, 5 days per week. Neurocognitive testing was performed before, during, and after treatment.

RESULTS

Nine of 12 patients entered on the study received BUdR. One of 3 patients in Cohort 1 developed leukoencephalopathy (LEP), a dose-limiting toxicity (DLT), within 2 months of the completion of therapy. Therefore, the next cohort received the same dose level. Because no toxicity was observed in Cohort 2, the third cohort received a BUdR dose of 1.8 g /m(2)/day. Shortly after completing enrollment in Cohort 3, 3 more patients developed LEP, including 2 from Cohort 1 who had received a dose of 1.5 g/m(2)/day. Thus, DLT occurred at a dose of 1.5 g/m(2)/day, the starting level in the current study. As a result, the trial was stopped. Eight of 12 patients achieved a complete response, 3 achieved a partial response, and 1 patient died before response assessment.

CONCLUSIONS

Hyperfractionated WBRT with concurrent BUdR after chemotherapy was found to result in modest disease control but has unacceptable neurotoxicity.

Oral brivudin in comparison with acyclovir for improved therapy of herpes zoster in immunocompetent patients: results of a randomized, double-blind, multicentered study

Brivudin [(E)-5-(2-bromovinyl)-2'-deoxyuridine] is a nucleoside analogue with a high and selective antiviral activity against varicella-zoster virus (VZV) and herpes simplex virus type 1 (HSV-1). The double-blind, randomized study presented here compared efficacy and safety of oral brivudin 1 x 125 mg and acyclovir 5 x 800 mg, both for 7 days, in 1227 immunocompetent patients with herpes zoster. Main results were as follows: brivudin was superior to acyclovir in accelerating the "time to last formation of new vesicles" (primary parameter; risk ratio(ITT): 1.13, P=0.014). Equivalent effects of brivudin and acyclovir were observed for the secondary parameters "time to first crust" (RR(ITT): 0.93, P=0.004), "time to full crusting" (risk ratio(ITT): 1.03, P<0.001), and "time to loss of crusts" (RR(ITT): 0.95, P=0.002). The incidence of potentially treatment-related adverse events was similar under brivudin (7.7%) and acyclovir (10.0%). In conclusion, brivudin proved to be more effective than acyclovir in terminating vesicle formation, the parameter which reflects the end of viral replication, thus confirming, in the clinical setting, the greater in vitro antiviral activity of brivudin. Compared with acyclovir, brivudin provides a similar safety profile and a significant improvement in efficacy.

Brivudine: a herpes virostatic with rapid antiviral activity and once-daily dosing

Brivudine is an analog of thymidine, and is incorporated into the viral DNA. It blocks the action of DNA polymerases, thus inhibiting viral replication. It has a stronger antiviral effect against the varicella-zoster virus compared with reference compounds such as aciclovir or penciclovir. The efficacy of brivudine has been documented in a number of clinical trials in patients with herpesvirus-related infections, particularly in patients with herpes-zoster. At a dose of 125 mg once daily, brivudine has proved to be superior to aciclovir with respect to reducing the period of new blister production in patients with herpes-zoster, and has shortened the duration of post-herpetic neuralgia. Tolerability was equivalent to that of aciclovir or placebo, with occasional gastrointestinal disorders leading to treatment withdrawal in a minority of patients.

Herpes zoster guideline of the German Dermatology Society (DDG)

Varicella zoster virus (VZV) causes varicella (chickenpox), remains dormant in dorsal root and cranial nerve ganglia and can be reactivated as a consequence of declining VZV-specific cellular immunity leading to herpes zoster (shingles). Patients older than 50 years of age affected by herpes zoster may suffer a significant decrease of quality of life. These patients and immunocompromised individuals are at increased risks for severe complications, involving the eye, the peripheral and the central nervous system (prolonged pain, postherpetic neuralgia). Such complications occur with and without cutaneous symptoms. The German Dermatology Society (DDG) has released guidelines in order to guarantee updated management to anyone affected by herpes zoster. Diagnosis is primarily clinical. The gold standard of laboratory diagnosis comprises PCR and direct identification of VZV in cell cultures. Detection of IgM- and IgA-anti VZV antibodies may be helpful in immunocompromised patients. Therapy has become very effective in the last years. Systemic antiviral therapy is able to shorten the healing process of acute herpes zoster, to prevent or to alleviate pain and other acute and chronic complications, particularly, when given within 48 h to a maximum of 72 h after onset of the rash. Systemic antiviral therapy is urgently indicated in patients beyond the age of 50 years and in patients at any age with herpes zoster in the head and neck area, especially in patients with zoster ophthalmicus. Further urgent indications are severe herpes zoster on the trunk and on the extremities, herpes zoster in immunosuppressed patients and in patients with severe atopic dermatitis and severe ekzema. Only relative indications for antiviral therapy exist in patients younger than 50 years with zoster on the trunk and on the extremities. In Germany acyclovir, valacyclovir, famciclovir and brivudin are approved for the systemic antiviral treatment of herpes zoster. These compounds are all well tolerated by the patients and do not differ with regard to efficacy and safety. Brivudin has a markedly higher anti-VZV potency than oral acyclovir, valacyclovir and famciclovir and thus offers a simpler dosing regimen. It must be given only once daily during 7 days in comparison to three and five times dosing per day of valacyclovir, famciclovir and acyclovir, respectively. Brivudin is an antiviral agent with no nephrotoxic properties, which is an advantage when compared to acyclovir. The most important aim of therapy of herpes zoster is to achieve painlessness. Appropriately dosed analgesics in combination with a neuroactive agent (i.e. amitriptylin) are very helpful when given together with antiviral therapy. The additive therapy with corticosteroids may shorten the degree and duration of acute zoster pain, but has no essential effect on the development of postherpetic neuralgia, which is a very difficult condition to treat. Thus early presentation to a pain therapist is recommended in specific cases.

Cellular transformation of the investigational new anticancer drug NB1011, a phosphoramidate of 5-(2-bromovinyl)-2'-deoxyuridine, results in modification of cellular proteins not DNA

NB1011 [E-5-(2-bromovinyl)-2'-deoxyuridine-5'-(L-methylalaninyl)-phenylphosphoramidate], a phosphoramidate prodrug of E-5-(2-bromovinyl)-2'-deoxyuridine-5'-monophosphate (BVdUMP), is an investigational new anticancer drug. NB1011 targets thymidylate synthase (TS), which catalyzes the transformation of BVdUMP into cytotoxic reaction products. Due to the elevated levels of TS expression in tumor cells compared to normal cells, these cytotoxic products are preferentially generated inside tumor cells, and, as expected, NB1011 is more toxic to cells with higher levels of TS expression. Therefore, NB1011 therapy should kill tumor cells without severely damaging normal cells. Radiolabeled NB1011 was used to determine the intracellular fate of NB1011 reaction products and, possibly, the mechanism of action of this investigational new drug. We found significant incorporation of the radiolabel into cellular macromolecules. In contrast to our expectations that NB1011 product(s) would be incorporated into DNA, we discovered that cellular proteins were the labeled macromolecular fraction. Herein, we report that the intracellular transformation of NB1011 involves formation of the corresponding monophosphate, TS-dependent transformation into highly reactive intermediates, and subsequent incorporation into cellular proteins. TS itself appears to escape irreversible inactivation. Our data suggest that protein modification not DNA incorporation accounts for the therapeutic effect of NB1011. The proposed mechanism is rather unexpected for a nucleotide analogue and could lead to the discovery of new cellular protein targets for future drug design.

A model of accelerated aging induced by 5-bromodeoxyuridine

We consider a scheme of aging with two possible mechanisms of senescence processes: aging with apoptosis and necrosis for differentiated cells and a multistage process of malignant transformation. Our model describes the multistage phenomena of aging and carcinogenesis by a set of stochastic equations using multivariate and diffusion processes. This model fits experimental data on the acceleration of aging processes from postnatal exposure to 5-bromodeoxyuridine (BrdU), and the induction of genome instability. The methods of stochastic modeling and computer simulation of the processes of aging and carcinogenesis have been used for the verification of the biological suggestions.

Vascular endothelial growth factor-A and -C protein up-regulation and early angiogenesis in a rat photothrombotic ring stroke model with spontaneous reperfusion

This study explored the temporal expression pattern of two subtypes of vascular endothelial growth factor (VEGF) proteins and three subforms of their receptors as well as endothelial proliferation in adult rats subjected to photothrombotic ring stroke with spontaneous reperfusion in the cortical region at risk. The exposed crania of halothane-anesthetized, temperature- and blood gas-controlled male Wistar rats were irradiated with a ring laser beam started simultaneously with systemic injection of the photosensitizer erythrosin B. Rats were repeatedly injected with 5-bromodeoxyuridine (BrdU) after stroke induction. Immunohistochemistry of coronal brain sections showed that VEGF protein subtype C increased simultaneously with subtype A in the ring lesion region at 2 h after irradiation. In the cortical region at risk (i.e., the penumbra-like zone), increased VEGF-C and VEGF-A immunostaining was seen at 24 h with sustained appearance up to 72 h after ischemic onset. Correspondingly, the VEGF-C-specific receptor flt-4 and the VEGF-A receptors flt-1 and flk-1 were up-regulated in a temporal sequence similar to that of their agonist proteins in the cortical ring lesion and the region at risk. At 48 h after stroke induction, proliferating BrdU-immunopositive endothelial cells formed microvessels in the post-ischemic cortical region at risk. These vessels became more pronounced at 72 h and were still visible at 100 days after the stroke. This study suggests that VEGF-C and its receptor flt-4 may cooperate with VEGF-A and its receptors flt-1 and flk-1 to promote early angiogenesis after stroke, which may in turn contribute to spontaneous reperfusion in this focal thromboembolic stroke model.

[Mathematical and simulating model of accelerated aging induced by 5-bromo-2-deoxyuridine]

The principles of stochastic modeling and simulation of the processes of aging and carcinogenesis by means of semimartingale methods are considered. The model fits to the experiments on activating of processes of aging be 5-bromodeoxiuridine postnatal exposure inducing genome instability. The model describes the multistage phenomena of aging and carcinogenesis by the system of stochastic equations in terms of multivariate and diffusion processes.

A phase II trial of high-dose bromodeoxyuridine with accelerated fractionation radiotherapy followed by procarbazine, lomustine, and vincristine for glioblastoma multiforme

PURPOSE

To conduct a Phase II study to evaluate the long-term efficacy and safety of high-dose 5'-bromodeoxyuridine (BrdU) and accelerated radiotherapy followed by procarbazine, lomustine (CCNU), and vincristine (PCV) chemotherapy in patients with glioblastoma multiforme.

METHODS AND MATERIALS

Between 1994 and 1996, 88 patients were enrolled to receive 1.9 Gy of radiation three times a day for two 5-day cycles separated by 2 weeks; each 5-day cycle was preceded by a continuous 96-hour infusion of BrdU at a dose of 2.1 g/m2/day. After radiotherapy, patients received PCV chemotherapy.

RESULTS

Median survival for all 88 patients was 50 weeks. Seventy (79.5 %) received one or more courses of PCV; their median survival was 57 weeks. Covariates predictive of improved survival were gross total versus subtotal resection or biopsy (p = 0.0048) and radiation dose > or = 56 Gy (p = 0.019). While receiving BrdU, 47 patients (53%) suffered grade 3 or 4 thrombocytopenia or leukopenia; 22 patients (25%) suffered grade 3 or 4 dermatologic toxicity.

CONCLUSION

Survival was not extended in patients with glioblastoma or gliosarcoma who received BrdU at the dose and administration schedule used in this study. The BrdU dose used in this study resulted in substantial myelosuppressive and dermatologic toxicity.

Bromodeoxyuridine alternating with radiation for advanced uterine cervix cancer: a phase I and drug incorporation study

PURPOSE

Preclinical studies show a significant increase in the ratio of the radiosensitizer bromodeoxyuridine (BUdR) in tumors versus the intestinal mucosa during the drug elimination period, compared with the ratio during drug infusion. We constructed a phase I study in patients with locally advanced cervix cancer, using alternating cycles of BUdR and radiation therapy (RT).

PATIENTS AND METHODS

Eighteen patients with stage IIB to IVA cervix cancer participated. A treatment cycle consisted of a 4-day BUdR infusion followed by a week of pelvic RT, 15 Gy twice daily in 1.5-Gy fractions. After three cycles, additional BUdR was infused, followed by brachytherapy. The fraction of thymidine replaced by BUdR and the fraction of cells incorporating BUdR were determined in rectal mucosa and tumor biopsies at the end of the first BUdR infusion (day 5), at the middle of the first RT week (day 10), and at the time of brachytherapy.

RESULTS

Dose-limiting toxicity was observed in one of 16 patients receiving 1,000 mg/m2/d x 4 days and in both patients receiving 1,333 mg/m2/d x 4 days each cycle. After a median follow-up of 39 months, 12 patients (66%) were free of pelvic disease and nine (50%) were alive and disease free. The ratio of tumor to rectum BUdR incorporation averaged 1.5 to 1.8 and did not differ significantly between day 5 and day 10. A trend toward reduced ratio was observed at brachytherapy. Drug-containing cells in rectal biopsies migrated from the crypts to the mucosal surface.

CONCLUSION

In this schedule, 1,000 mg/m2/d is the maximum-tolerated dose of BUdR. BUdR incorporation levels in tumors were consistent with clinically significant radiosensitization. The migration of BUdR-containing rectal mucosa cells from the crypts to the surface at the time of RT suggests that this regimen may offer a relative sparing of the mucosa from radiosensitization.

Oral brivudin vs. intravenous acyclovir in the treatment of herpes zoster in immunocompromised patients: a randomized double-blind trial

The efficacy of oral brivudin vs. intravenous acyclovir was compared in a randomized multicentered study under double-blind conditions using the double-dummy technique. Forty-eight patients with a herpes zoster rash less than 72 hours in duration were entered in the study. Brivudin was given as one 125-mg tablet every 6 hours. Acyclovir was infused over 1 hour at a dose of 10 mg/kg every 8 hours. Treatment was continued for 5 days. There was no significant difference between the treatment groups when analyzed in terms of new lesion formation, increase in the area of rash within the primary dermatome, cutaneous dissemination, and affection of mucous membranes or visceral organs. Both treatment regimes were also equally effective in the time to full crusting of lesions. Oral brivudin and intravenous acyclovir were well tolerated by most patients. There was no need to interrupt the treatment in any case. As effective as intravenous acyclovir in the treatment of herpes zoster, oral brivudin offers the potential for outpatient treatment of herpes zoster in immunocompromised patients.

Radiation therapy and bromodeoxyuridine chemotherapy followed by procarbazine, lomustine, and vincristine for the treatment of anaplastic gliomas

PURPOSE

To conduct a Phase II study to evaluate the long-term efficacy and safety of radiotherapy combined with intravenous bromodeoxyuridine for patients with anaplastic glioma tumors.

METHODS AND MATERIALS

Between 1983 and 1987, study patients received 1.7-1.8 Gy radiation once a day, Monday through Friday, to a total dose of 60 Gy. On the Thursday prior to beginning radiotherapy and for the next 5 weeks (6 weeks total), patients received a continuous 96 h intravenous infusion of bromodeoxyuridine at 0.8 g/m2/24 h; following radiotherapy, patients received procarbazine, lomustine (CCNU), and vincristine (PCV) for 1 year or until tumor progressed.

RESULTS

One-hundred thirty eight patients (median age, 43 years) were evaluable for analysis. Estimated 4-year survival for the anaplastic astrocytoma (AA) stratum (n = 116) is 46%. For the astrocytoma (ASTRO) stratum (n = 22), the 6-year survival is estimated at 79%. Estimated 4-year progression-free survival for AAs is 42%, and for ASTROs, 68%. Whole brain irradiation was used in 23% and limited-field irradiation in 77%; patients receiving limited-field irradiation had a better survival rate (p = 0.07). Total tumor resection was performed in 15%, partial resection in 53%, and biopsy only in 32%. For the 81 patients with tumor recurrence, 34 (42%) are known to have received additional treatment(s). For AA, fits of the Cox proportional hazards regression model showed that covariates individually predictive of survival were younger age (p < 0.001), Karnofsky performance score (p = 0.10). Major toxicities were rash during Weeks 1 through 6 requiring dose modification in 14%, Grade > or = III leukopenia in 18%, and Grade > or = III thrombocytopeni in 9%.

CONCLUSION

The study suggests that the bromodeoxyuridine-radiotherapy-PCV, compared with other published therapies, can improve progression-free survival, and aggressive treatment of ASTRO patients can lead to substantial increases in survival compared to published survival data.

The application of 5-bromodeoxyuridine in the management of CNS tumors

A variety of clinical reports have described the application of the bromodeoxyuridine labeling index as an adjunct to conventional pathological examination of CNS tumors. This index has proven useful in predicting the clinical outcome associated with many such tumors. Furthermore, because of its efficacy as a radiosensitizing agent, bromodeoxyuridine (and the closely related iododeoxyuridine) has been used in combination with radiation therapy for malignant glial neoplasms, with some encouraging results. Although most studies suggest that bromodeoxyuridine is safe, there is evidence that this compound does have potential side-effects, including the observation that it is a mutagen and carcinogen in some experimental systems. A number of new alternative approaches for predicting the clinical outcome of CNS tumors has been developed based on an increased understanding of their molecular biology. However, until such approaches are better characterized, the clinical application of bromodeoxyuridine will continue to play an important role in predicting the clinical behavior of many CNS tumors.

Evaluation of bromodeoxyuridine in glioblastoma multiforme: a Northern California Cancer Center Phase II study

In a study activated in 1983 and closed in 1987, the Brain Tumor Research Center of the University of California and the Northern California Cancer Center evaluated the effect of bromodeoxyuridine in the treatment of glioblastoma multiforme. A total of 160 patients were evaluable of 173 entered. Patients were to receive a bromodeoxyuridine infusion of 0.8 g/m2 daily over 24 hours for 4 days of each of 6 weeks of radiotherapy directed to the tumor plus a margin delivering a total of 60 Gy. Eligibility requirements included Karnofsky performance status greater than or equal to 70, biopsy or resection and central pathology review by one of the authors. Following radiotherapy patients were to receive chemotherapy with procarbazine, CCNU, and vincristine for 1 year. Median survival was 55.7 weeks and time to failure, 34.5 weeks for the evaluable group of 160 patients. In a univariate analysis the variables that influence survival and time to failure were: age, Karnofsky performance status, bromodeoxyuridine dose and the delivery of at least one procarbazine, CCNU, and vincristine cycle following radiotherapy. In multivariate analysis, age, Karnofsky performance status, and bromodeoxyuridine dose remain significant for time to failure; age and Karnofsky performance status remain significant for survival.

Relationship of DNA strand breakage produced by bromodeoxyuridine to topoisomerase II activity in Bloom-syndrome fibroblasts

Cells from patients with Bloom syndrome, a cancer-prone disorder with cutaneous photosensitivity and spontaneous chromosome breakage, exhibit an abnormally increased number of sister-chromatid exchanges following treatment with 5-bromodeoxyuridine (BrdU). This effect has been postulated to be mediated by abnormal topoisomerase II activity. We used alkaline elution to measure DNA single-strand breakage following prolonged exposure to BrdU. Five-day exposure to BrdU produced equal numbers of alkali-labile sites in normal and Bloom-syndrome fibroblasts. These breaks were not protein-associated but were produced by alkali. Treatment with topoisomerase II inhibitors induced similar frequencies of DNA single-strand breaks in normal and Bloom-syndrome fibroblasts. These findings imply that BrdU incorporation into cellular DNA induces alkali-labile DNA lesions that are independent of topoisomerase II activity in Bloom and normal cells.

Intra-arterial bromodeoxyuridine radiosensitization of malignant gliomas

In the 1950's it was first observed that mammalian cells exposed to the halogenated deoxyuridines were more sensitive to ultraviolet light and radiation than untreated cells. This prompted early clinical trials with bromodeoxyuridine (BUdR) which showed mixed results. More recently, several Phase I studies, while establishing the feasibility of continuous intravenous (IV) infusion of BUdR, have reported significant dose limiting skin and bone marrow toxicities and have questioned the optimal method of BUdR delivery. To exploit the high mitotic activity of malignant gliomas relative to surrounding normal brain tissue, we have developed a permanently implantable infusion pump system for safe, continuous intraarterial (IA) internal carotid BUdR delivery. Since July 1985, 23 patients with malignant brain tumors (18 grade 4, 5 grade 3) have been treated in a Phase I clinical trial using IA BUdR (400-600 mg/m2/day X 8 1/2 weeks) and focal external beam radiotherapy (59.4 Gy at 1.8 Gy/day in 6 1/2 weeks). Following initial biopsy/surgery the infusion pump system was implanted; BUdR infusion began 2 weeks prior to and continued throughout the 6 1/2 week course of radiotherapy. There have been no vascular complications. Side-effects in all patients have included varying degrees of anorexia, fatigue, ipsilateral forehead dermatitis, blepharitis, and conjunctivitis. Myelosuppression requiring dose reduction occurred in one patient. An overall Kaplan-Meier estimated median survival of 20 months has been achieved. As in larger controlled series, histologic grade and age are prognostically significant. We have shown in a Phase I study that IA BUdR radiosensitization is safe, tolerable, may lead to improved survival, and appears to be an efficacious primary treatment of malignant gliomas.

The ocular effects of intracarotid bromodeoxyuridine and radiation therapy in the treatment of malignant glioma

Since July 1985, 23 patients have been entered into a phase I/II clinical trial using intraarterial 5-bromodeoxyuridine (BUdR) (400-600 mg/m2 daily for 8.5 weeks) and focal external beam radiotherapy (59.4 Gy at 1.8 Gy daily in 6.5 weeks) in the treatment of malignant gliomas (Kernohan grades 3 and 4). The side effects in all patients have included varying degrees of anorexia, fatigue, ipsilateral forehead dermatitis, blepharitis, and conjunctivitis. Mucopurulent conjunctivitis and exposure keratitis developed in several patients and spontaneous corneal perforation developed in one. Eyes from two individuals examined at autopsy showed significant changes. Animal studies that predated clinical trials using rhesus monkeys did not predict the ophthalmologic complications seen in human subjects.

Mucocutaneous complications of intraarterial 5-bromodeoxyuridine and radiation

5-Bromodeoxyuridine (BUDR), a halopyrimidine thymidine analogue, is incorporated into the DNA of dividing cells and causes photoradiosensitization. Twenty-five patients with malignant astrocytomas were treated with continuous intracarotid BUDR radiosensitization and radiotherapy for 8 1/2 weeks. Unique dose-limiting mucocutaneous complications were encountered. Ipsilateral facial dermatitis with epilation of eyebrows and eyelashes, ocular irritation, and bilateral nail dystrophy developed in all patients. Less common reactions included oral ulceration in six patients, body exanthem on the trunk in five, and atypical erythema multiforme major in one.

Intra-arterial 5-bromo-2-deoxyuridine (BUdR) radiosensitization with external beam radiation in rhesus monkeys: toxicity study

A primate toxicity study was performed to test the hypothesis that BUdR does not increase the likelihood of unilateral or bilateral central nervous system damage secondary to radiation therapy. BUdR, a halogenated pyrimidine analog is incorporated into DNA of dividing cells and sensitizes them to radiation. It is best given unilaterally, intra-arterially by continuous infusion because of its regional advantage (Rd) estimated to be between 11 and 16. Six rhesus monkeys were implanted with a Model 400 Infusaid pump perfusing the right internal carotid artery. Three of the six monkeys received intra-arterial (IA) BUdR infusion plus whole brain external beam radiation (6,000 R over 6 weeks) and three received radiation alone. The two BUdR treated animals completing radiation developed symmetric bilateral high signal aberrations on MRI in the frontal, parietal, and occipital centrum semiovale and corona radiata at nine months. At autopsy, confluent microinfarcts were found to correspond topographically to the MRI abnormalities. In the radiation alone group, two animals had normal MRI and autopsy while the third animal had bilateral MRI high signal aberrations develop sequentially with corresponding microinfarcts at autopsy. These changes were greater in severity than those seen in the BUdR treated animals. We support previous evidence that there is differential intraspecies sensitivity to radiation. We find that BUdR produces no unilateral potentiation of radiation toxicity.

Clinical trial of intravenous infusion of bromodeoxyuridine (BUdR) for radiosensitization of malignant brain tumors

Bromodeoxyuridine (BUdR) is a radiosensitizer that can be incorporated into cellular DNA as a substitute for thymidine at the time of DNA synthesis. As the steady-state arterial concentration of BUdR given by means of intravenous infusion was recently presented, the possibility of revival of BUdR as a radiosensitizer administered by the intravenous route was suggested. Based on the experience of BAR therapy and phase-I studies by NIH and UCSF, 12 hours of BUdR at a dose of 800-1,000 mg/m2 for five days a week was given to 23 patients with primary and secondary malignant brain tumors during radiation therapy. Radiation therapy was planned at a weekly dose of 10 Gy for five to six weeks. Fifteen patients received 1,000 mg/m2 of BUdR; six of them tolerated more than three weeks of treatment. In eight patients given doses of 800 mg/m2, five patients tolerated more than three weeks. The most remarkable toxic effects were myelosuppression and stomatitis, which were major obstacles to maintaining the schedule. More than 50% reduction of tumor volume was obtained in five of 12 cases of evaluated gliomas (42%) and three of four cases of metastatic tumors (75%). The median time to tumor progression in seven patients with glioblastoma was 37 weeks.

Distinctive eruption characterized by linear supravenous papules and erythroderma following broxuridine (bromodeoxyuridine) therapy and radiotherapy

A distinctive cutaneous eruption occurred in two patients with central nervous system tumors who were treated with broxuridine (bromodeoxyuridine) and radiotherapy. Findings included the initial appearance of papular lesions within skin directly overlying acral superficial veins and the later development of a more generalized eruption eventuating into exfoliative erythroderma.

Intra-arterial infusion of radiosensitizer (BUdR) combined with hypofractionated irradiation and chemotherapy for primary treatment of osteogenic sarcoma

Combined modality treatment was given in nine patients of osteogenic sarcoma wherein the tumor was unresectable because of location or amputation was refused. This alternative to massive surgery comprised hypofractionated irradiation, intra-arterial infusion of the radiosensitizer 5'-bromodeoxyuridine (BUdR) and adjuvant systemic chemotherapy. Local control was achieved in seven of the nine patients. Four survived, all without evidence of disease at 6, 7.1, 8.8, and 10.5 years after completion of irradiation. Pulmonary metastases developed in six patients--of whom one survives, following high-dose pulmonary irradiation and additional chemotherapy. Significant soft-tissue injury occurred in five patients. On the basis of our experience, we believe that new approaches using modifications of external beam irradiation with different fractionation schedules or better radiosensitizing compounds may hold promise for patients with non-resectable osteosarcoma.

Continuous intravenous infusions of bromodeoxyuridine as a clinical radiosensitizer

Twelve patients were treated with continuous intravenous (24-hour) infusions of bromodeoxyuridine (BUdR) at 650 or 1,000 mg/m2/d for up to two weeks. Myelosuppression, especially thrombocytopenia, was the major systemic toxicity and limited the infusion period to nine to 14 days. However, bone marrow recovery occurred within seven to ten days, allowing for a second infusion in most patients. Local toxicity (within the radiation field) was minimal, with the exception of one of four patients, who underwent abdominal irradiation. Pharmacology studies revealed a steady-state arterial plasma level of 6 X 10(-7) mol/L and 1 X 10(-6) mol/L during infusion of 650 and 1,000 mg/m2/d, respectively. In vivo BUdR uptake into normal bone marrow was evaluated in two patients by comparison of preinfusion and postinfusion in vitro radiation survival curves of marrow CFUc with enhancement ratios (D0-pre/D0-post) of 1.8 (with 650 mg/m2/d) and 2.5 (with 1,000 mg/m2/d). In vivo BUdR incorporation into normal skin and tumor cells using an anti-BUdR monoclonal antibody and immunohistochemistry was demonstrated in biopsies from three patients revealing substantially less cellular incorporation into normal skin (less than 10%) compared with tumor (up to 50% to 70%). We conclude that local and systemic toxicity of continuous infusion of BUdR at 1,000 mg/m2/d for approximately two weeks is tolerable. The observed normal tissue toxicity is comparable with our previous clinical experience with intermittent (12 hours every day for two weeks) infusions of BUdR. Theoretically, a constant infusion should allow for greater incorporation of BUdR into cycling tumor cells and thus, for further enhancement of radiosensitization.

Identification of bromodeoxyuridine in malignant and normal cells following therapy: relationship to complications

During a clinical Phase I study of bromodeoxyuridine (BUdR) as a radiation sensitizer we identified the normal and malignant cells that incorporated the BUdR. BUdR was infused for up to 14 days and the in vivo incorporation of BUdR into DNA was assessed using an immunohistochemical technique and a monoclonal antibody directed against BUdR. BUdR was identified in 50% of breast cancer cells and 10% of cells in a malignant melanoma. BUdR was also found in the basal layer of the normal epidermis and in 50% of cells in the marrow. The incorporation of BUdR into cells in the epidermis and marrow may produce the phototoxicity and myelosuppression observed in patients treated with BUdR. Sequential biopsies from a breast cancer taken prior to and following radiotherapy suggested that cells that incorporated BUdR may have been selectively killed by the radiation. The immunohistochemical technique used to identify BUdR appeared to be useful for studies of in vivo and in vitro cell proliferation.

Radiosensitization of hematopoietic precursor cells (CFUc) in glioblastoma patients receiving intermittent intravenous infusions of bromodeoxyuridine (BUdR)

The potential use of bromodeoxyuridine (BUdR) as a radiosensitizer given by an intermittent intravenous route is being studied in a Phase I/II trial at the National Cancer Institute. In order to assess the extent of radiosensitization, we have studied the radiation response of human bone marrow cells CFUc taken from 6 patients prior to and after a 14-day infusion of BUdR. Varying concentrations (1000-1500 mg) of BUdR were infused for 12 hours every 24 hours for up to 14 consecutive days. Cell survival was determined by colony formation of CFUc in soft agar suspension. X ray survival curves were generated over a dose range of 0-300 rad and the slopes of the survival curves (DO) before and after BUdR infusion were compared. Radiation enhancement ratios (ER) (DO pre-BUdR/DO post-BUdR) ranged from 1.0-2.2 and appeared to be BUdR dose dependent. Above 650 mg/m2, the radiation ER was greater than or equal to 1.5. Dose dependent systemic toxicity to bone marrow and skin was also observed with intermittent intravenous infusions of BUdR. From our study, it appears that an intravenous dose of less than 700 mg/m2/12 hours is well tolerated and may result in radiosensitization of CFUc in man.

Teratogenic and clastogenic effects of BUdR in mice

Pregnant mice (C57B1/6JFfm) were treated with BUdR on day 9 of gestation. For doses ranging from 300 to 1,200 mg/kg b.w. of BUdR the teratogenic effect in near-term fetuses was analyzed. The findings confirm the phase and dose dependency of the induced malformations found by other authors. They also demonstrate, however, a BUdR-specific induction of special malformations. For a dose of 1,200 mg/kg of BUdR the effect on mitotic rates and the induction of chromosomal aberrations were investigated. Mitotic rates were counted in single organs as well as in total homogenized embryos. The methods are equally useful. The embryos were analyzed 3, 6, 12, and 24 hours after BUdR treatment either after homogenization or in serial sections. Decrease of mitotic rates has been found to be most remarkable at 3 and 12 hours after treatment. At 24 hours only the neural tissue showed a slight decrease of the mitotic rate. Chromosomal aberrations are induced at all times, but the highest rates are seen at 3 and 12 hours after treatment. The aberrations are of the chromatid type.

Sister chromatid exchange induced by anti-herpes drugs

The rate of sister chromatid exchange induced by several anti-herpes agents was measured to assess their potential mutagenicity. The agents--5-iodo-deoxyuridine (IDU), 5-trifluoromethyl-deoxyuridine (TFT), and [E]-5-(2-bromovinyl)-deoxyuridine (BVDU)--were incubated at various concentrations with human lymphocytes and fibroblasts, and that rate of sister chromatid exchanges was measured. In lymphocytes and fibroblasts BVDU and IDU did not induce exchange except at concentrations of 50 mg/l, while TFT increased the rate of exchange at a concentration of 0.5 mg/l. The rate of sister chromatid exchange is a sensitive index of chromosomal damage, and these findings provide information on the safety of some of the antiherpes agents tested. TFT increased the rate of exchange at a concentration that coincides with its minimal antiviral concentration, but BVDU did not induce exchange at therapeutic concentrations.

Clastogenic effect of BrdU on different phases of human lymphocyte "in vitro" cell cycle

From the data presented, it can be pointed out a mitotic delay in the cell cycle, possibly due to BrdU cytotoxic effect. Irradiation in G1 phase does not produce any increase in SCE frequency while irradiation in S or G2 phase increases significantly this frequency. Our data support the hypothesis that BrdU does not produce by itself an increase of chromosome aberrations but act as sensitizer for cells which have incorporated it.

The effects of "BAR" therapy on oral malignant tumors

"BAR" therapy is a combined therapy with BUdR (Radiosensitizer), Antimetabolites (5-FU, FT-207 etc.) and Radiation for malignant tumours. How radiation can be reduced as far as possible and how the effects of treatment can be increased as much as possible are the objectives of this study of combining radiation and BUdR therapy. The authors attempted to irradiate 3-5 days after the BUdR and antimetabolite had been infused via the superficial temporal artery, in 12 malignant oral tumours (11 squamous cell carcinomas and 1 reticulum-cell sarcoma). BUdR 50-250 mg/day, antimetabolites (5-FU) 10-250 mg/day and a total irradiation dose of 6000 rads by 6 MeV Linac X-ray or Co-60 gamma ray, 200 rads/day were given. 9 marked responses, 2 moderate responses and 1 no response (2 cases were operated on by local resection) were obtained by the authors. Side effects of treatment were observed during the course of "BAR" therapy. Stomatitis was found in all patients and it occurred on the mucosa of the tumour-affected site especially. Dermatitis of the skin of the face was noted in 6 cases, resembling irradiation dermatitis. Fever was observed in 4 cases and it always occurred after irradiation. Diarrhoea was noted in 3 cases and occurred before irradiation, 2 out of 3 were given BUdR 0.1 g and the remaining one was given BUdR 1 g, and 5-FU lg. In addition, there were: 1 loss of appetite, 1 nausea and 1 exfoliation of nails.

Neural-tube defects caused by 5-bromodeoxyuridine in chicks

Chick embryos were explanted at HH stage 4 and cultured for 24 h on thin albumen with 10 mug/ml 5-bromodeoxyuridine (BrdU). BrdU inhibited closure of the neural tube in over 90% of the embryos. Mitotic figures were found throughout adversely effected neuroepithelium, suggesting that interkinetic nuclear migration had been inhibited. Electron microscopic studies of BrdU-treated neural-tube cells showed fewer and more amorphous cytoplasmic extensions, microfilaments, and demosomal (juctional) tonofibrils than in controls, but microtubules were unaffected.

Incorporation of 5-lododeoxyuridine into the DNA of mouse embryos: its relation to embryotoxicity

Pregnant female ICR mice were administered, ip, either a trace (200 muCi/kg) or teratogenic (200 muCi + 300 mg/kg) dose of [6(-3)H] 5-iododeoxyuridine (IdU) on day 10 of gestation. Maternal liver, spleen, intestine, and kidneys, and placentas and embryos were removed at various time intervals after injection, weighed, and homogenized in cold 0.5 m perchloric acid. The half-lives of IdU-derived nucleotides in the acid-soluble fraction ranged from 31-46 min (trace) to 57-131 min (teratogenic) for the tissues analyzed. [3H]IdU was incorporated into the DNA of all mitotically active tissues after both dosages. The presence of the label in iodouracil was demonstrated by thin-layer chromatography of DNA bases extracted from maternal spleen and embryo. Growth of embryos following injection on day 10 resulted in decreased 3H-specific activity in the DNA fraction and concomitant retention of total activity. It is suggested that the previously demonstrated embryotoxicity of IdU is related to its retention at its presumed intracellular site of action.