Regional 'pro-drug' gene therapy: intravenous administration of an adenoviral vector expressing the E. coli cytosine deaminase gene and systemic administration of 5-fluorocytosine suppresses growth of hepatic metastasis of colon carcinoma

Direct administration of an adenoviral vector expressing the cytosine deaminase gene (AdCMV.CD) to tumors of colon carcinoma cells, with concomitant systemic administration of 5-fluorocytosine (5FC), results in local production of 5-fluorouracil (5FU) and suppression of tumor growth. Based on the demonstration that in vivo adenovirus-mediated gene transfer to intrahepatic tumors is relatively inefficient compared with in vivo gene transfer to hepatocytes, we developed a 'regional' prodrug strategy using in vivo Ad-mediated CD gene transfer to normal liver, permitting hepatocytes to convert 5FC into 5FU to treat local metastasis effectively in a 'trans' fashion. To show that hepatocytes can generate and export sufficient 5FU to achieve this goal, primary rat hepatocytes were exposed to AdCMV.CD and 5FC. Evaluation of the supernatants by spectrophotometry and by HPLC demonstrated significant conversion of 5FC into 5FU. When supernatants of hepatocytes exposed to AdCMV.CD and 5FC were transferred to cultures of CT26 mouse colon carcinoma cells, the CT26 viability was reduced by 80%. To show that this regional AdCMV.CD/5FC prodrug strategy can suppress tumor growth in vivo, a model of metastatic colon carcinoma was established by injecting CT26 cells into the left lobe of the liver of syngeneic Balb/c mice. The next day, AdCMV.CD was transferred to hepatocytes by intravenous administration, and 5FC treatment was started the following day. Evaluation of tumor growth after 15 days showed marked suppression of tumor growth in AdCMV.CD- and 5FC- treated animals compared to control groups (P < 0.007). We conclude that primary hepatocytes are capable of converting 5FC into 5FU and exporting sufficient amounts of 5FU to the local milieu to suppress the growth of liver metastases of colon carcinoma cells.

[New antiviral agents in the treatment of chronic hepatitis B and C]

Interferon (IFN) is the drug universally used in the treatment of B and C chronic hepatitis. Due to its low efficacy, 40% in the treatment of chronic hepatitis B and 10-20% in the treatment of chronic hepatitis C, and to its adverse events, in some cases severe, new antiviric molecules are being investigated. Lamivudin, famciclovir and the association of ribavirin and IFN are the more relevant and will be clinically accepted in an immediate future. It is also probable that rigid indications for hepatic transplantation in patients with liver cirrhosis by B virus change in the next years due to the use of these new antiviric drugs before and after transplantation. In this revision we analyze the current situation of these new therapies. However, most information come from pilot studies, and multicentric randomized studies are needed to establish firm conclusions about the role that these new therapies are going to play in the treatment of viral chronic hepatitis.

Severe hepatic dysfunction after adenovirus-mediated transfer of the herpes simplex virus thymidine kinase gene and ganciclovir administration

The use of so-called 'suicide' genes to activate prodrugs has been effective in animal models for several solid tumor types and is now in phase I and II clinical trials. We have exploited adenovirus vectors (Ad) for transfer and expression of the herpes simplex virus thymidine kinase (HSVtk) gene to render rat colorectal liver metastases sensitive to the anti-herpetic agent ganciclovir (GCV). The efficacy and toxicity of this enzyme-prodrug combination were tested after in situ transduction of rat colorectal tumor cells and after intraportal administration of the vector Ad.CMV.TK. Our results demonstrate the validity of the approach but reveal that hepatic expression of HSVtk, both in tumor bearing and in tumor-free rats, provokes severe liver dysfunction and mortality upon GCV administration. These data show, that in contrast to the common assumption, normally non-mitotic tissues too, can be affected by adenovirus-mediated HSVtk transfer and subsequent GCV treatment. Given the hepatotropic nature of systemically administered adenovirus type 2- and 5-derived vectors, it will be essential to monitor liver functions of patients included in all gene therapy trials involving adenoviral vectors with the HSVtk gene.

Allopurinol as an additive to quinine in the treatment of acute complicated falciparum malaria

The emergence of chloroquine resistance, and a world-wide scarcity of quinine, have resulted in a search for newer antimalarial drugs directed against falciparum malaria. Allopurinol causes virtually complete inhibition of purine biosynthesis of malaria parasites, which may prove lethal to the parasites. This study was designed to examine if allopurinol is additive to quinine in the treatment of acute falciparum malaria. Forty-seven Asian-Indian adults with acute complicated falciparum malaria were assigned to a treatment period of five days. They were randomly assigned to receive either oral allopurinol (12 mg/kg in three divided doses for five days) plus quinine (600 mg intravenously every 8 hr for two days, followed by 600 mg orally every 8 hr for three days ) (n = 24), or quinine alone (600 mg intravenously every 8 hr for two days, followed by 600 mg orally every 8 hr for three days) (n = 23). The responses were assessed by parasite clearance time, defervescence time, splenomegaly disappearance time, and cure rate. In the allopurinol-quinine (ALLQUIN)-treated group, all the durations were significantly shorter than those in the quinine alone (QUIN)-treated group. They were ALLQUIN versus QUIN (mean +/- SD = 65.33 +/- 11.47 hr versus 76.78 +/- 18.20 hr; P = 0.0214; 57.66 +/- 13.01 hr versus 82.52 +/- 23.55 hr, P = 0.0002; 10 +/- 1.64 days versus 14.65 +/- 2.4 days; P = 0.0002), respectively. The cure rate was higher in the ALLQUIN group (91.7%) than in the QUIN group (87%). However, this difference was not statistically significant. Therefore, this study indicates that allopurinol can be an additive to quinine to bring about both faster eradication of Plasmodium falciparum and clinical remission than with quinine alone.

Technique and outcome of combined phacoemulsification and trabeculectomy

The efficacy of combined surgery for the treatment of concurrent glaucoma and cataract has long been under scrutiny. Comparisons between sequential surgery and combined procedures have shown mixed results, and current guidelines have been drawn for the indication of combined surgery. The evolution of combined triple surgery--cataract extraction, intraocular lens implantation, and filtering procedure--has evolved from planned extracapsular cataract extraction to small-incision phacoemulsification. The improvements of phacoemulsification over extracapsular surgery have naturally given rise to improvements in the results of combined procedures; good outcomes in both intraocular pressure control and visual acuity have been reported along with low complication rates. The techniques of combined phacoemulsification-trabeculectomy are under continual development as new sutureless incisions, filtration procedures, and antimetabolite use are studied. The results of numerous studies show that the combined procedure is an effective method of treatment of glaucoma and cataract. This review examines various recent aspects of the combined procedure, phacoemulsification-trabeculectomy, antimetabolites, results and complications, as well as current developments of new techniques. In addition, we review studies on combined cataract extraction and trabeculectomy, including older literature on planned extracapsular extraction plus trabeculectomy as well as newer studies on phacoemulsification-trabeculectomy.

Sonographic diagnosis of triplet tubal pregnancy after in vitro fertilization and embryo transfer

Ectopic pregnancy (EP) after in vitro fertilization and embryo transfer (IVF/ET) is not rare, but triplet tubal pregnancy after IVF/ET is very rare. We describe a patient with hydrosalpinx in whom a triplet tubal pregnancy occurred on the same side as the hydrosalpinx. Close hormonal and sonographic monitoring of pregnancies achieved through IVF is recommended to ensure the early diagnosis of EP and to avert complications. A triplet tubal EP was considered highly probable after 3 gestational sacs were observed outside the uterus during sonography performed at 6 weeks' gestation. Therapeutic laparoscopy was then performed because methotrexate treatment failed. Appropriate management strategies are discussed.

Preoperative idoxuridine and radiation for large soft tissue sarcomas: clinical results with five-year follow-up

BACKGROUND

Local control remains an important issue in the management of large soft tissue sarcomas. Radiation is the main adjuvant to surgery for local therapy of sarcomas, but it requires relatively high doses, hitherto considered prohibitive in areas such as the retroperitoneum. We developed a preoperative treatment approach to large soft tissue sarcomas that would deliver a high total dose of radiation administered in conjunction with the halogenated pyrimidine radiosensitizer idoxuridine (IdUrd).

METHODS

Thirty-seven patients with large sarcomas of the head and neck, mediastinum, retroperitoneum, or extremity received three or five cycles of sequential IdUrd infusion (1000-1600 mg/m2/d x 5 d) alternating weekly with twice daily radiation (125-150 cGy per dose) and were then evaluated for resection. The delivered preoperative radiation dose was up to 6250 to 7500 cGy.

RESULTS

Five patients (14%) had a partial response to preoperative therapy, and 28 of 37 patients underwent successful resection. There were no intra- or postoperative deaths. Local control was achieved in 19 of 28 resected patients, but in only 1 of 6 patients who remained unresectable despite therapy. With a median follow-up of 5.8 years, 28% of patients are alive with no evidence of disease, 17% are alive with disease, and 53% have died of their disease.

CONCLUSIONS

Using the dose and schedule we employed, resection of large soft tissue sarcomas was possible after high-dose radiation delivered in conjunction with IdUrd. Although local control was acceptable, the high rate of distant failure represents a limitation of any local approach to the treatment of large soft tissue sarcomas and suggests the need for integration of this approach with an effective systemic therapy.

Long-term results and complications after trabeculectomy with a single per-operative application of 5-fluorouracil

We retrospectively evaluated a consecutive series of 45 patients (45 eyes) who underwent trabeculectomy augmented with a single intra-operative 5 minute application of 5-fluorouracil (5-FU; 25 mg/ml). All patients were at an increased risk of subconjunctival fibrosis and surgical failure. The mean follow-up period was 24 months (range 12-42, SD 6.9). The mean pre-operative intraocular pressure (IOP) was 29.1 mmHg (SD 6.1) and the mean IOP at the last post-operative visit was 16.6 mmHg (SD 6.4) (p < 0.0001) with a mean IOP reduction of 42%. The number of medications reduced from a mean of 2.3 (SD 0.7) pre-operatively, to 0.8 (SD 0.7) post-operatively (p < 0.0001) and 22 eyes (49%) required no topical treatment for IOP control. An IOP of 21 mmHg or less with or without medications was achieved in 80% of cases. There was no significant difference in final IOP or success rate over time between low- and high-risk patients, although the low-risk patients did better in the first 12-18 months. Complications included hypotony maculopathy in 2 cases (4%), leaking bleb in 5 cases (11%) and giant bleb in 1 case (2%), giving a total of 8 cases (18%) with bleb-related sequelae. In the short to medium term, a single per-operative application of 5-FU is a useful adjunctive treatment during glaucoma filtering surgery for low- to moderate-risk cases, although a steady increase in the failure rate was associated with increasing length of follow-up.

Correction of lower eyelid retraction in thyroid eye disease: a randomised controlled trial of retractor tenotomy with adjuvant antimetabolite versus scleral graft

BACKGROUND/AIMS

Lower eyelid retraction in thyroid eye disease contributes to ocular discomfort and an unsightly appearance, especially if asymmetrical. The use of donor scleral grafts is effective in lengthening the lower eyelids but carries a risk of virus transmission. Other techniques, including those which do not use grafts, need to be compared with scleral grafts. Recurrent retraction is a recognised complication of thyroid eyelid surgery; therefore, the authors investigated the use of antimetabolites to reduce postoperative fibrosis.

METHODS

In this prospective randomised controlled trial of 25 patients (35 eyelids), the use of donor sclera in 20 lower eyelids (13 patients) was compared with partial tenotomy of the anterior part of the lower eyelid retractors (ALER) with adjuvant peroperative antimetabolite in 15 lower eyelids (12 patients). A 5 minute peroperative application of either 5-fluorouracil (25 mg/ml) in nine lower eyelids (eight patients) or mitomycin C (0.2 mg/ml) in six lower eyelids (four patients) was used to focally inhibit fibroblasts. Follow up ranged from 3 to 18 months (mean 7.8).

RESULTS

One month after surgery the results of both groups were similar. However, at 3 months after surgery the results of scleral grafting were better than tenotomy with antimetabolites: 3/12 patients (25%) treated with tenotomy and adjuvant antimetabolite required subsequent surgery using grafts for correction of recurrent retraction. There were no significant complications associated with the use of antimetabolites in the eyelid in the doses used in this study.

CONCLUSIONS

This randomised prospective trial shows that donor scleral grafts were more effective in the long term than partial tenotomy with adjuvant antimetabolite in the correction of lower eyelid retraction associated with thyroid eye disease. The use of peroperative antimetabolites in the lower eyelid was safe.

Effect of allopurinol on postasphyxial free radical formation, cerebral hemodynamics, and electrical brain activity

OBJECTIVE

Free radical-induced postasphyxial reperfusion injury has been recognized as an important cause of brain tissue damage. We investigated the effect of high-dose allopurinol (ALLO; 40 mg/kg), a xanthine-oxidase inhibitor and free radical scavenger, on free radical status in severely asphyxiated newborns and on postasphyxial cerebral perfusion and electrical brain activity.

METHODS

Free radical status was assessed by serial plasma determination of nonprotein-bound iron (microM), antioxidative capacity, and malondialdehyde (MDA; microM). Cerebral perfusion was investigated by monitoring changes in cerebral blood volume (delta CBV; mL/100 g brain tissue) with near infrared spectroscopy; electrocortical brain activity (ECBA) was assessed in microvolts by cerebral function monitor. Eleven infants received 40 mg/kg ALLO intravenously, and 11 infants served as controls (CONT). Plasma nonprotein-bound iron, antioxidative capacity, and MDA were measured before 4 hours, between 16 and 20 hours, and at the second and third days of age. Changes in CBV and ECBA were monitored between 4 and 8, 16 and 20, 58 and 62, and 104 and 110 hours of age.

RESULTS

Six CONT and two ALLO infants died after neurologic deterioration. No toxic side effects of ALLO were detected. Nonprotein-bound iron (mean +/- SEM) in the CONT group showed an initial rise (18.7 +/- 4.6 microM to 21.3 +/- 3.4 microM) but dropped to 7.4 +/- 3.5 microM at day 3; in the ALLO group it dropped from 15.5 +/- 4.6 microM to 0 microM at day 3. Uric acid was significantly lower in ALLO-treated infants from 16 hours of life on. MDA remained stable in the ALLO group, but increased in the CONT group at 8 to 16 hours versus < 4 hours (mean +/- SEM; 0.83 +/- 0.31 microM vs 0.50 +/- 0.14 microM). During 4 to 8 hours, delta CBV-CONT showed a larger drop than delta CBV-ALLO from baseline. During the subsequent registrations CBV remained stable in both groups. ECBA-CONT decreased, but ECBA-ALLO remained stable during 4 to 8 hours of age. Neonates who died had the largest drops in CBV and ECBA.

CONCLUSION

This study suggests a beneficial effect of ALLO treatment on free radical formation, CBV, and electrical brain activity, without toxic side effects.

Routine diagnosis of herpes simplex virus (HSV) encephalitis by an internal DNA controlled HSV PCR and an IgG-capture assay for intrathecal synthesis of HSV antibodies

BACKGROUND

The development of antiviral therapy increases the need for rapid, sensitive and reliable methods or combination of methods for diagnosis and monitoring herpes simplex encephalitis, HSE.

OBJECTIVES

Evaluation of diagnostic performance of three successively developed HSV PCR assays when combined with a new capture ELISA for HSV intrathecal antibody production (ITT).

STUDY DESIGN

During a 3.6 year period a total of 4.206 CSF and serum samples from about 4.140 hospitalized patients with a tentative diagnosis of HSE were analyzed by a new ELISA for ITT. 1.962 CSF samples were examined also by PCR. Clinical signs and symptoms and additional tests were obtained on all ITT and/or PCR positive patients. In 1993 the PCR was a double PCR. In 1994 the PCR was a single PCR with internal inhibition control. Positive samples were confirmed by a different confirmative PCR to increase the specificity. From 1995 the PCR was as in 1994 but samples were no longer divided in the serology routine laboratory.

RESULTS

A total of 33 HSE cases was found (incidence 1.8 HSE per million people). All patients were treated with aciclovir. Three patients died, 9 patients had primary infection, 2 patients had HSE previously, and 2 patients relapsed. Only 11 patients recovered satisfactory. Of all 37 positive ITT 7 were unlikely positive. False positive PCR was seen in 1993 and 1994, due to sample-to-sample contamination during division of samples, but was not seen since 1995 when this procedure was changed. The test results depended on the state of the disease. Thus, the sensitivity, specificity, PPV and NPV for ITT were highest when performed more than 1 week after debut of symptoms whereas these values were highest using PCR within the first week.

CONCLUSION

Routine PCR diagnosis of HSE type 1 and 2 is a highly sensitive and specific method that should be performed together with serological ITT to cover the whole time span from debut of symptoms to several weeks after hospitalization.

Does intermittent "pulse" topical 5-fluorouracil therapy allow destruction of actinic keratoses without significant inflammation?

BACKGROUND

Topical 5-fluorouracil (5-FU) is effective in removing actinic keratoses but causes unsightly and painful erosions. Intermittent "pulse" 5-FU therapy has been described as being an effective and comfortable technique for destroying actinic keratoses.

OBJECTIVE

The purpose of this study was to determine the efficacy and cutaneous side effects of intermittent 5-FU therapy.

METHODS

Efficacy of treatment was evaluated by three experienced dermatologists separately comparing randomly arranged before and after photographs. Degree of skin reaction was graded from photographs taken during treatment.

RESULTS

Of 13 patients treated with intermittent 5-FU, two had an excellent result, three a good result, but eight failed to show discernible improvement. Efficacy was linked to the degree of skin irritation.

CONCLUSION

Pulse 5-FU failed to clear actinic keratoses in most patients. Intermittent 5-FU treatment does not dissociate its therapeutic efficacy from its undesirable erosive effects. Pulse therapy is a less intensive way of employing 5-FU and may be of value in patients unwilling to accept the erosions and discomfort that accompany the traditional course of daily 5-FU applications.

Pharmacokinetics and clearance of ganciclovir during continuous hemodiafiltration

OBJECTIVE

To evaluate the ganciclovir pharmacokinetics and clearance during continuous venovenous hemodiafiltration.

DESIGN

Case report.

SETTING

General intensive care unit of a tertiary care emergency department.

PATIENTS

A 63-yr-old female who has a history of active behçet's disease that has been controlled with oral prednisolone, and who has chronic renal failure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A 5-mg/kg dosage of ganciclovir was administered intravenously over a 60-min period under continuous venovenous hemodiafiltration. Samples from the arterial and venous blood catheters and from the ultradiafiltrate were collected over the next 12 hrs to calculate pharmacokinetic parameters and clearance of hemodiafiltration. The pharmacokinetic parameters were as follows: half-life of elimination phase 12.6 hrs; total clearance 0.55 mL/min/kg; and volume distribution of steady state 27.07 L. The clearance of hemodiafiltration was 0.63 mL/min/kg.

CONCLUSION

Continuous venovenous hemodiafiltration is effective in removing ganciclovir from the blood.

Protection against Leishmania major challenge infection in mice vaccinated with live recombinant parasites expressing a cytotoxic gene

A "suicide" system based on thymidine kinase-ganciclovir combination was developed and tested in a Leishmania major experimental model. Susceptible BALB/c mice were infected with L. major expressing the thymidine kinase gene of herpes simplex virus type 1 and treated for 2 consecutive weeks with 7.5 mg/kg/day ganciclovir at different times from the initial infection. Ganciclovir treatment at varying times after infection had different effects on the outcome of disease. A complete inhibition of intracellular parasites was obtained in mice treated 1 or 4 days after infection, whereas ganciclovir administration 2 weeks later resulted in the control of infection only when the drug was provided. Variable levels of protection, from partial to total, against challenge infection with virulent L. major were observed, depending on the timing of ganciclovir treatment. The thymidine kinase-ganciclovir approach represents an excellent experimental model to control Leishmania infection and to evaluate the immunologic response of the host.

Multicomponent gene therapy vaccines for lung cancer: effective eradication of established murine tumors in vivo with interleukin-7/herpes simplex thymidine kinase-transduced autologous tumor and ex vivo activated dendritic cells

Multiple antitumor modalities may be necessary to overcome lung tumor-mediated immunosuppression and effectively treat non-small cell lung cancer (NSCLC). To evaluate a multimodality gene therapy approach for control of local tumor growth, a weakly immunogenic murine alveolar cell carcinoma, L1C2, was transduced with either the interleukin-7/hygromycin-herpes simplex thymidine kinase (IL-7/HyHSVtk) internal ribosome entry site (IRES) retroviral vector or a vector containing the HyHSVtk, but not the IL-7 gene. Of the many cytokines available for gene transfer, IL-7 was chosen for these studies because it both stimulates CTL responses and down-regulates tumor production of the immunosuppressive peptide TGF-beta. Following selection in hygromycin, IL-7 transduction was confirmed by ELISA. Clones produced 1.25 to 10 ng of IL-7/ml/10(6) cells per 24 h. In vitro, genetically modified tumor cells were significantly more sensitive to ganciclovir (GCV) than unmodified parental tumor cells. The in vivo growth of ex vivo modified L1C2 cells was evaluated. There was a dose-response relationship between the amount of IL-7 secreted in vitro and the growth of genetically modified murine tumor in vivo. Transduced tumor cells regressed in mice following GCV therapy. Although ex vivo gene modification of tumor cells led to complete resolution of the tumor following implantation in vivo, IL-7 and HSVtk gene modified tumor cells were not effective in treating established parental tumors. However when 5 x 10(5) bone marrow-derived, in vitro activated dendritic cells (DC) were administered in combination with transduced tumor and GCV, 5 day old established tumors were eradicated in 80% of mice. These studies suggest that multicomponent vaccines may facilitate improved host responses by replacing host immune deficits and thus could have a role in adjuvant therapy and local control of NSCLC.

Hyperammonemic encephalopathy after chemotherapy. Survival after treatment with sodium benzoate and sodium phenylacetate

A 16-year-old boy had hyperammonemia and encephalopathy develop after high-dose chemotherapy for acute lymphoblastic leukemia. He was treated successfully with the ammonia-trapping agents sodium benzoate and sodium phenylacetate.

Visceral leishmaniasis in patients infected with the human immunodeficiency virus

The experience with 52 episodes of visceral leishmaniasis diagnosed in 43 patients is reported. The most common symptoms were fever (81%), splenomegaly (65%), hepatomegaly (63%), and pancytopenia (73%). In 79% of the patients, CD4+ cell counts were < 100 cells/mm3. Prior or simultaneous diagnosis of AIDS was made in 29 (67%) patients. Diagnosis was considered fortuitous in 19% of the episodes. In 27% of the episodes, the diagnosis was made on the basis of demonstration of parasites outside the reticuloendothelial system, chiefly blood (7 cases) and gastrointestinal mucosa (5 cases). Parasites were frequently observed or cultured from blood (22/37 episodes) or the digestive tract (8/9 episodes). High antimony doses were more effective than low doses in achieving clinical or parasitological cure (rate of cure, 80% vs. 40%, p = 0.11). Severe toxicity was observed in six (11.7%) of the 51 treated episodes. Severe AIDS-related diseases [odds ratio (OR) 10, p < 0.05] and CD4+ counts (OR 12, p < 0.05) were independent factors for early death. Prophylaxis with monthly pentamidine was not useful in reducing relapses of visceral leishmaniasis.

Steroid-sparing alternative treatments for sarcoidosis

Alternatives to corticosteroids for the treatment of sarcoidosis are reviewed. These include cytotoxic agents such as methotrexate, azathioprine, and cyclophosphamide. In addition, agents such as hydroxychloroquine and cyclosporine are reviewed. The efficacy, toxicity, and timing of these drugs in the management of sarcoidosis is discussed.

Urate oxidase in prevention and treatment of hyperuricemia associated with lymphoid malignancies

Standard prophylaxis and treatment of malignancy-associated hyperuricemia in the USA has been allopurinol with vigorous hydration, urinary alkalinization and osmotic diuresis. Urate oxidase, the enzyme that converts uric acid to allantoin (a readily excreted metabolite that has 5- to 10-fold higher solubility than uric acid), is an alternative therapy; however, few published findings support this practice. Between February 1994 and December 1996, we administered non-recombinant urate oxidase (Uricozyme) to 126 children with newly diagnosed non-B cell acute lymphoblastic leukemia (ALL) during the first 5 days of chemotherapy with methotrexate, 6-mercaptopurine or both. Their blood levels of uric acid and other indicators of tumor lysis were measured at diagnosis and during treatment and then compared with findings in 129 similarly treated historical controls who had received allopurinol to control hyperuricemia. Clinical responses to urate oxidase were also determined in eight patients with newly diagnosed B cell ALL or advanced-stage non-Hodgkin lymphoma. Patients treated with urate oxidase had rapid and significantly greater decreases in their blood uric acid levels than did the historical controls (median maximal level during treatment, 2.3 vs 3.9 mg/dl, P < 0.001). They also had lower creatinine (0.6 vs 0.7 mg/dl, P = 0.01) and blood urea nitrogen (11 vs 24 mg/dl, P < 0.001) levels. Similar findings were made in the eight cases of B cell ALL or non-Hodgkin lymphoma. None of the patients required dialysis for acute renal failure. Six (4.5%) of the 134 children given urate oxidase had allergic reactions, manifested primarily by urticaria, bronchospasm and hypoxemia. Thus, non-recombinant urate oxidase is a more effective uricolytic agent than allopurinol but is associated with acute hypersensitivity reactions, even in patients without a history of allergy.

HSV-1 thymidine kinase gene therapy for colorectal adenocarcinoma-derived peritoneal carcinomatosis

Peritoneal carcinomatosis is a common clinical situation which, in most cases, cannot be eradicated by surgery or chemotherapy. The feasibility of an HSV-TK-based suicide gene therapy for peritoneal carcinomatosis induced by DHD/K12 colon carcinoma cells was investigated. DHD/K12 cells stably expressing the tk gene were killed in vitro in the presence of low concentrations of ganciclovir, they exhibited a 'bystander effect' when mixed with TK-negative cells. BD-IX rats injected intraperitoneally, either directly or after surgical peritoneal irritations, with DHD/K12 cells developed peritoneal carcinomatosis within 2 weeks. Ganciclovir treatment of animals injected with DHD/K12-TK cells allowed a significant reduction of the tumor volume as well as a prolonged survival. Of these animals 35-40% showed a long-term disease-free survival after ganciclovir therapy. Residual or relapsing tumors could be explained by a low expression of the transgene as demonstrated by RT-PCR.