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Treatment of cytomegalovirus esophagitis in patients with acquired immune deficiency syndrome: a randomized controlled study of foscarnet versus ganciclovir. The Italian Cytomegalovirus Study Group.

OBJECTIVE: Although several uncontrolled studies have shown that the response rate to ganciclovir and foscarnet for all forms of cytomegalovirus (CMV) infection in immunocompromised patients is almost similar, to date, no controlled clinical trial has been specifically designed to compare these two agents in the treatment of CMV esophagitis. The aim of this study was, therefore, to compare the efficacy and safety of these two drugs in the induction therapy of CMV esophagitis in patients with acquired immunodeficiency syndrome (AIDS). METHODS: Thirty-nine of 211 (18%) consecutive AIDS patients undergoing endoscopy for esophageal symptoms had macroscopic esophagitis that proved to be sustained by CMV based on the documentation of typical intranuclear inclusions at histology; 23 were considered eligible for this study and were randomized to receive foscarnet 90 mg/kg b.i.d. or ganciclovir 5 mg/kg b.i.d. for 21 days. Twelve patients received foscarnet, whereas 11 were treated with ganciclovir. Clinical and laboratory evaluation was performed weekly, and endoscopy was repeated at the end of therapy. The two treatment groups were well balanced as to the following characteristics at entry: age, sex, absolute number of CD4 cells, duration of AIDS, Karnofsky score, frequency of concomitant Candida esophagitis (grade I or II), and severity of esophageal symptoms. RESULTS: Marked endoscopic improvement (complete disappearance of macroscopic lesions or significant reduction of the endoscopic score) was observed in eight of 11 (73%) of foscarnet and seven of 10 (70%) of ganciclovir-treated patients, and inclusion bodies disappeared from follow-up biopsies in 55% and 50% of patients, respectively. The symptomatic response was also similar for both treatments: 82% of patients who received foscarnet and 80% of those treated with ganciclovir had a complete or at least a good clinical response. Frequency of adverse events was comparable with both drugs: only one patient in each group suspended treatment because of severe side effects. CONCLUSIONS: Foscarnet and ganciclovir appear to be similarly effective and safe in the induction therapy of AIDS-related CMV esophagitis. Consequently, the choice of the anti-CMV agent should be tailored to the individual patient according to the different toxicity profiles of the two drugs.

AIDS-Related Opportunistic Infections↗

Foscarnet treatment of cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome.

Ten patients with acquired immunodeficiency syndrome with newly diagnosed cytomegalovirus (CMV) retinitis were treated with an induction regimen of intravenous foscarnet, 60 mg/kg of body weight, administered as a 2-h infusion and repeated every 8 h for 14 days. At the end of induction, 9 of 10 patients had stabilized (no new retinal lesions and stable old lesions [7 patients]) or improved (decreased retinal opacification [2 patients]). All eight patients with CMV in urine or blood upon entry into the study had negative urine and blood cultures at the end of induction. After induction therapy, seven patients continued maintenance foscarnet therapy, 60 mg/kg as a single daily infusion, 5 days/week. In six patients, retinal lesions increased in size after 2 to 32 weeks of maintenance therapy. One was invaluable because a retinal detachment developed. Only 9 of 42 blood and urine cultures obtained during maintenance foscarnet therapy yielded CMV, compared with 7 of 14 obtained prior to the initiation of foscarnet induction therapy (P = 0.04). Foscarnet toxicity was mild and infrequent: elevation in serum creatinine by 0.5 to 1.3 mg/dl over the base line (two patients), muscle twitching (three patients), hemoglobin decrease by 1 mg/dl (two patients), nausea (two patients), absolute neutrophil count decrease by 50% (one patient), rise in serum phosphorus to greater than 5.5 mg/dl (four patients), and proteinuria (two patients). Intermittently administered intravenous foscarnet appears to be an effective, relatively nontoxic therapy for CMV retinitis. Additional studies to determine the optimal dosage for maintenance therapy are needed, as are comparative trials with ganciclovir.

Acquired Immunodeficiency Syndrome↗

Pharmacokinetics of foscarnet and distribution to cerebrospinal fluid after intravenous infusion in patients with human immunodeficiency virus infection.

To investigate the pharmacokinetics and effects of intravenous foscarnet, 13 relatively healthy male patients with human immunodeficiency virus infection and a mean CD4+ lymphocyte value of 0.45 x 10(-9) cells per liter were given a continuous intravenous infusion of foscarnet (0.14 to 0.19 mg/kg per min) for 8 to 21 days. Blood and urine samples were taken during and after drug administration to monitor foscarnet concentrations. Lumbar puncture was performed during the infusion in five patients. The concentrations in plasma showed large variations both within and between patients. The disposition of foscarnet could be explained by a triexponential equation (t1/2 lambda 1, 0.40 to 2.52 h; t1/2 lambda 2, 3.20 to 16.7 h; t1/2 lambda 3, 36 to 196 h). Renal clearance accounted for most of the plasma clearance, the difference probably reflecting the passage of foscarnet into bone. Up to 20% of the cumulative dose may have been deposited in bone 7 days postinfusion. Foscarnet was distributed to the cerebrospinal fluid in a concentration varying from 13 to 68% of the simultaneous concentration in plasma. Polyuria and polydipsia were recorded in all patients. There appears to be an association between the degree of malaise, including symptoms such as nausea, vomiting, fatigue, and headache, and concentrations in plasma above 350 mumol/liter.

Acquired Immunodeficiency Syndrome↗

Relationship between 3'-azido-3'-deoxythymidine resistance and primer unblocking activity in foscarnet-resistant mutants of human immunodeficiency virus type 1 reverse transcriptase.

Phosphonoformate (foscarnet) is a pyrophosphate (PP(i)) analogue and a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), acting through the PP(i) binding site on the enzyme. HIV-1 RT can unblock a chain-terminated DNA primer by phosphorolytic transfer of the terminal residue to an acceptor substrate (PP(i) or a nucleotide such as ATP) which also interacts with the PP(i) binding site. Primer-unblocking activity is increased in mutants of HIV-1 that are resistant to the chain-terminating nucleoside inhibitor 3'-azido-3'-deoxythymidine (AZT). We have compared the primer-unblocking activity for HIV-1 RT containing various foscarnet resistance mutations (K65R, W88G, W88S, E89K, S117T, Q161L, M164I, and the double mutant Q161L/H208Y) alone or in combination with AZT resistance mutations. The level of primer-unblocking activity varied over a 150-fold range for these enzymes and was inversely correlated with foscarnet resistance and directly correlated with AZT resistance. Based on published crystal structures of HIV-1 RT, many of the foscarnet resistance mutations affect residues that do not make direct contact with the catalytic residues of RT, the incoming deoxynucleoside triphosphate (dNTP), or the primer-template. These mutations may confer foscarnet resistance and reduce primer unblocking by indirectly decreasing the binding and retention of foscarnet, PP(i), and ATP. Alternatively, the binding position or orientation of PP(i), ATP, or the primer-template may be changed in the mutant enzyme complex so that molecular interactions required for the unblocking reaction are impaired while dNTP binding and incorporation are not.

Antiviral Agents↗

Topical treatment of recurrent genital herpes infections with foscarnet.

In a double-blind study 86 patients with a total of 129 episodes of recurrent genital herpes were treated topically with 0.3% foscarnet or placebo cream. All patients considered, healing time was significantly shortened in the foscarnet group as compared to the placebo group (p less than 0.01). Subgrouped by sex, the healing time among men treated with foscarnet was significantly shortened as compared to those treated with placebo (p less than 0.002), whereas no statistical significant difference was observed among women. Foscarnet treated men with subpreputial lesions had a shorter period of ulcers (1.7 days) than placebo (3.4 days) treated men (p less than 0.02). Overall, foscarnet treatment reduced the period of redness, swelling, blisters and ulcers. Foscarnet was well tolerated, only in 1/57 patients treated was a moderate local adverse reaction recorded.

Administration, Topical↗

Foscarnet and ganciclovir in the treatment of cytomegalovirus retinitis.

Induction regimens of foscarnet and ganciclovir are highly effective in arresting cytomegalovirus (CMV) retinitis in patients with AIDS. Chronic maintenance therapy is nonetheless required to forestall progression of disease following induction. In open studies of these two agents in AIDS patients with CMV retinitis at dosages similar to those currently recommended, median times to retinitis progression during maintenance therapy of as long as greater than 100 days have been observed. In a randomized comparative trial of immediate and delayed foscarnet treatment utilizing rigorously defined end points, the mean times to retinitis progression were 13.3 weeks among patients receiving immediate foscarnet therapy and 3.2 weeks among those receiving no treatment. In a similar trial of ganciclovir, the mean times to progression were 68.5 days among patients receiving immediate treatment and 22.9 days among those receiving no treatment. Experience in a number of studies not designed to assess mortality has suggested that specific antiviral treatment for CMV retinitis is associated with prolongation of survival. One retrospective analysis of survival patterns in patients treated with ganciclovir has suggested a significant effect of this agent on survival; another analysis has shown no association between anti-CMV therapy and survival, with the relative hazard of death among patients receiving foscarnet therapy being equivalent to that among patients receiving ganciclovir therapy. In the one randomized study comparing the mortality of patients receiving initial treatment with either foscarnet or ganciclovir, foscarnet-treated patients had a median survival of 12.6 months compared with 8.5 months for ganciclovir-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytomegalovirus Infections↗

A novel mutation in the UL54 gene of human cytomegalovirus isolates that confers resistance to foscarnet.

Foscarnet is currently licensed for the treatment of human cytomegalovirus (HCMV) infection. Mutations proven to confer resistance to foscarnet have mostly been mapped to regions II, III and VI of the HCMV UL54-encoded DNA polymerase. We previously showed that sequential foscarnet-resistant HCMV isolates recovered from a patient with lymphoma had change N495K in region delta-C of the DNA polymerase. To evaluate the impact of change N495K on HCMV sensitivity to foscarnet, a recombinant HCMV strain carrying the mutation was produced by homologous recombination. The recombinant virus showed a 3.4-fold increase in foscarnet resistance, and remained sensitive to ganciclovir and cidofovir. In addition, the recombinant strain showed a reduction of infectious virus yield compared with its parent strain. Change N495K should be added to the list of mutations conferring resistance to foscarnet and be taken into account in the genotypic diagnosis of antiviral resistance.

Antiviral Agents↗

[Foscarnet sodium for treatment in patients with severe chronic hepatitis B].

OBJECTIVE: To investigate the effectiveness of foscarnet sodium in the treatment of severe chronic hepatitis B. METHODS: Two hundred and eight patients were enrolled in a multicenter, double-blind, controlled study. The patients received foscarnet sodium (foscarnet group) or saline (control group) injections for 4 weeks, and were then followed for 24 weeks. RESULTS: HBV DNA negative rate was 12.8% in the foscarnet group and 7.1% in the control group at the end of treatment; and it was 5.5% and 3.0% at the end of the follow-up period respectively (P > 0.05). The rate of HBV DNA decrease of more than 2 log copies/ml was 53.2% in the foscarnet group and 16.2% in the control group at the end of treatment, and 23.9% and 8.1% (P < 0.01) respectively at the end of the follow-up period. The rate of HBV DNA < 10(5) copies/ml was 64.2% and 30.3% at week 4 in the two groups respectively, and 40.4% and 22.2% (P < 0.01) at the end of the follow-up period. HBeAg negative rate was 17.3% and 5.8% at the end of the treatment, and 22% and 5.4% at the end of the follow-up period (P < 0.01). The rate of HBeAg seroconversion was 12.7% and 3.7% at week 4, and 16.7% and 1.5% at the end of the follow-up period. Response rate was 60.6% and 21.2% at the end of week 4 (P < 0.05). CONCLUSION: Foscarnet sodium injection has a good effect on severe chronic hepatitis B patients and it is safe to use on them.

Adolescent↗

A dose escalation study to determine the toxicity and maximally tolerated dose of foscarnet.

OBJECTIVE: To determine the maximum tolerated dose of intravenous foscarnet (trisodium phosphonoformate hexahydrate); and to examine antiviral activity at plasma levels shown to inhibit HIV-1. DESIGN: Dose escalation study in three male subjects with AIDS who received foscarnet by continuous intravenous infusion at a dose of 200 mg/kg per day, after a 20 mg/kg loading dose. The dose was increased until a plasma level > 150 micrograms/ml was attained. RESULTS: Foscarnet was discontinued due to progressive renal insufficiency in all three patients (days 11, 19, and 21). Renal function normalized in all three, and no adverse sequelae due to foscarnet were observed at 1 year of follow-up. A seizure was observed in one patient on day 19. Maximum daily doses of foscarnet achieved were 395 mg/kg, 389 mg/kg, and 523 mg/kg. No changes in serum Ca2+, Mg2+, or PO4- were observed. CONCLUSIONS: Renal effects and toxicity of foscarnet in evolving renal insufficiency is self-limiting and reversible when the drug is discontinued. Incremental increases in dose can result in rapid rises in the plasma level with renal failure and may be compounded by concomitant medications and underlying illnesses.

Acquired Immunodeficiency Syndrome↗

Foscarnet treatment in various cytomegalovirus infections.

We examined the effect of foscarnet (Foscavir) in 15 AIDS patients with cytomegalovirus infection. Cytomegalovirus infection was presented as retinits (n = 8), colitis (n = 3), oral (n = 1) and perianal ulcers (n = 3) and pneumonitis (n = 1). Induction therapy with foscarnet showed a complete response in 9 and a partial response in 6 patients after a medium therapy of 3.5 weeks. Three patients showed progressive disease under ganciclovir and were treated subsequently with foscarnet. Main side effects were ulcers of the glans penis (n = 6) and a rise of creatinine (> 1.5 mg/dl; n = 4). Therapy was changed to ganciclovir because of renal toxicity in 1 patient receiving induction therapy with foscarnet. Within a period of foscarnet therapy between 5 and 9 months (median: 7 months) no clinical progression occurred. Medium survival after diagnosis of cytomegalovirus infection was 7.4 months. We describe our experience with foscarnet and compare treatment results of cytomegalovirus infection at certain locations.

Acquired Immunodeficiency Syndrome↗

Controversies in the treatment of cytomegalovirus retinitis: foscarnet versus ganciclovir.

Cytomegalovirus (CMV) retinitis is the most common intraocular infection in patients with AIDS. Untreated, CMV retinitis is a binding disease. Ganciclovir, a nucleoside analog, and foscarnet, a pyrophosphate analog, are both effective in controlling CMV retinitis. A randomized, controlled, comparative trial of foscarnet and ganciclovir demonstrated that they were equivalent in terms of controlling CMV retinits, but that foscarnet was associated with a longer survival, possibly due to an antiretroviral effect of foscarnet. However, foscarnet was less well tolerated than ganciclovir, primarily due to the nature of its side effects. Because foscarnet and ganciclovir have different side effects, initial treatment of CMV retinitis should be individualized. Newer technological developments, including oral ganciclovir and the ganciclovir intraocular device, may influence the choice of initial treatment, particularly because of their effect on the quality of life when compared to chronic intravenous therapy. The occurrence of relapse and the development of resistance remain long-term concerns, which may alter the use of anti-CMV drugs over time.

AIDS-Related Opportunistic Infections↗

Combination ganciclovir and foscarnet in the treatment of clinically resistant cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome.

OBJECTIVE: To assess the clinical response and patient tolerance to daily infusions of both ganciclovir sodium and foscarnet sodium for the treatment of clinically resistant cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome. DESIGN AND PATIENTS: Nine patients with clinically resistant cytomegalovirus retinitis who had shown progression of retinitis despite extended intravenous induction single-drug therapy or alternating therapy with induction doses of ganciclovir or foscarnet at 6 weeks were subsequently treated with a combination of ganciclovir and foscarnet. The dosing regimen for induction combination therapy was ganciclovir at 5 mg/kg every 12 hours and foscarnet at 60 mg/kg every 8 hours. Maintenance combination therapy was ganciclovir at 5 mg/kg every 12 to 24 hours and foscarnet at 90 to 120 mg/kg every day. Patients were observed closely for signs of a toxic effect or intolerance to the drug regimen. RESULTS: All patients exhibited a favorable response to combination therapy, with complete healing of retinitis in 12 of 14 eyes and partial healing of retinitis with decreased border activity and a cessation of border advancement in two of 14 eyes. Two of the nine patients stopped receiving combination therapy before completion of the study owing to their dissatisfaction with the time commitment. The regimen was otherwise well tolerated, with no significant medical toxic effects attributable to the drugs requiring cessation of therapy. CONCLUSIONS: Combination anticytomegalovirus therapy should be considered in those patients who have shown a poor clinical response to sustained single-drug induction therapy and alternating drug therapy. As survival time for patients with cytomegalovirus retinitis continues to improve, clinical resistance may become more common. Further work to delineate the optimal dosing and indications for combination therapy will be important.

AIDS-Related Opportunistic Infections↗

Inhibitory effects of foscarnet on herpesvirus multiplication in cell culture.

The effect of phosphonoformate (INN; foscarnet sodium) on Herpes Simplex Virus type 1 replication in cell-culture has been studied. At 55 microM, foscarnet reduced the yield by 50 per cent which correlated well with a 50 per cent reduction of plaque formation at 60 microM. Foscarnet had to be added before 8 hours post infection to inhibit virus production. The inhibition of herpesvirus plaque formation by the presence of foscarnet for 24 hours was not reversed by the removal of the drug. The inhibition of virus replication by foscarnet could, in contrast to the inhibition by acycloguanosine, not be reversed by addition of deoxynucleosides.

Animals↗

Maintenance therapy for cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome: foscarnet.

The use of ganciclovir in the treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) is limited by marrow toxicity and by the development of resistance to this agent in CMV strains capable of causing progressive disease. Foscarnet retains activity against ganciclovir-resistant CMV and has an adverse effect profile different from that of ganciclovir. Preliminary data from studies conducted under the AIDS Clinical Trials Group (ACTG) program indicate that intravenous foscarnet maintenance therapy at 60, 90, and 120 mg/kg/day in AIDS patients with CMV retinitis successfully completing foscarnet induction therapy is associated with median times to retinitis progression of 90, 95, and greater than 123 days, respectively. An ACTG trial of foscarnet in patients failing ganciclovir therapy has been initiated, as has a trial jointly sponsored by the National Eye Institute and the National Institute of Allergy and Infectious Diseases comparing the safety and efficacy of foscarnet and ganciclovir. Also underway is a trial evaluating the effects of combination and alternating regimens of these two agents.

Antiviral Agents↗

Foscarnet decreases serum and liver duck hepatitis B virus DNA in chronically infected ducks.

Foscarnet (trisodium phosphonoformate) is a new antiviral compound with in vitro inhibitory effects against the DNA polymerases of hepadna viruses. To study the effects of the drug in chronic hepadna virus infection, we treated ducks chronically infected with duck hepatitis B virus for 10 days with either low-dose foscarnet (50 mg/kg i.p. b.i.d.), high-dose foscarnet (250 mg/kg i.p. b.i.d.), or sterile water injections. Serum duck hepatitis B virus DNA and intrahepatic replicative forms of the virus were measured using molecular biological techniques with both a double-stranded radiolabeled DNA probe and a plus-strand (noncoding) specific RNA probe. We found a dose-related decrease in serum and intrahepatic duck hepatitis B virus DNA during treatment, with a rapid return toward baseline values after the cessation of treatment. There was a disproportionate decrease in the plus strand of viral DNA with treatment. We conclude that foscarnet exerts its effect in hepadna virus infection through inhibition of viral DNA polymerase. Further study is necessary to determine whether foscarnet, by itself or in combination with other treatment modalities, has a role to play in the treatment of chronic hepatitis B infections in humans.

Animals↗

Mode of interference of trisodium phosphonoformate (INN: foscarnet sodium), with influenza virus mRNA synthesis.

Foscarnet has previously been shown to inhibit influenza RNA polymerase activity. In this report the mode of inhibition of foscarnet has been investigated by enzyme-kinetic procedures and product analysis. Foscarnet shows noncompetitive inhibition with respect to ATP, CTP, and UTP, and a mixed inhibition with respect to GTP. In the presence of foscarnet the initiation of the mRNA synthesis can still occur, but the elongation is inhibited. The block of mRNA formation by foscarnet seems to occur after the synthesis of the 12-nucleotide-long conserved sequence found at the 5 prime end of the viral message.

Animals↗

Studies of ocular complications of AIDS Foscarnet-Ganciclovir Cytomegalovirus Retinitis Trial: 1. Rationale, design, and methods. AIDS Clinical Trials Group (ACTG).

Cytomegalovirus (CMV) retinitis is the most common intraocular infection in patients with AIDS and affects an estimated 20% of these patients. Two drugs, ganciclovir and foscarnet, are currently available for the treatment of CMV retinitis. The Foscarnet-Ganciclovir CMV Retinitis Trial was designed: (1) to evaluate the relative efficacy and safety of foscarnet and ganciclovir for the treatment of CMV retinitis in patients with AIDS; and (2) to compare the relative benefits of immediate treatment versus deferral of the treatment for patients with disease not involving the posterior pole. Prior to randomization, patients were assigned to one of two strata based upon the location and extent of retinitis in the more severely involved eye. Patients with retinitis in zone 1 (posterior pole) or extensive retinitis (extent greater than or equal to 25% retina) in zones 2 and/or 3 (peripheral retina) were randomly assigned to immediate treatment with either ganciclovir or foscarnet. Patients with CMV retinitis confined to less than or equal to 25% of the retina and in zones 2 and/or 3 were offered the option of participating in the comparison of immediate treatment versus deferral of treatment. Patients opting to participate in this comparison were randomly assigned to immediate treatment versus deferral. Patients preferring to choose either immediate treatment or deferral (treatment preference design) were randomized only to foscarnet or ganciclovir for treatment of CMV retinitis. Patients in the deferral group were started on drug treatment when the retinitis became more immediately sight-threatening either by virtue of location (involvement of zone 1) or size (extent greater than 25% of the retina). Outcome measures included: survival, retinitis progression, visual function (visual acuity and visual field), drug side effects, and morbidity. Enrollment in the trial began in March 1990 and was completed in October 1991.

Acquired Immunodeficiency Syndrome↗

Hypocalcemia induced by foscarnet (Foscavir) infusion in dogs.

Foscarnet (Foscavir) is an antiviral drug for intravenous (i.v.) treatment of cytomegalovirus (CMV) retinitis in immunocompromised patients. The drug forms complexes with divalent metal ions such as Ca2+ and serum calcium levels may be affected during its i.v. infusion. In this study, the effect on calcium homeostasis was investigated during daily 8-hr infusions of foscarnet in dogs. After priming infusions of 40 or 80 mg/kg administered during 0.5 hr, maintenance infusion rates were 46 or 91 mg/kg/hr (total daily doses of 410 or 810 mg/kg). At the low infusion rate, foscarnet was administered for 5 consecutive days. The mean plateau serum concentration was 0.56 mmol/liter and the main clinical sign was vomiting. Total serum calcium was reduced from about 2.5 to 2.0 mmol/liter and ionized calcium from 1.3 to 0.9 mmol/liter. Parathyroid hormone (PTH) levels in serum were elevated three to six times while calcitriol (1,25-(OH)2D3) levels were unaffected. At the high infusion rate, treatment was discontinued after 1-2 days of dosing due to pronounced adverse clinical signs such as extensive vomitings, apathy, ataxia, and muscle spasms. The mean serum plateau concentration of foscarnet at this dose level was 1.2 mmol/liter. Total serum calcium was reduced from 2.5 to 1.6 mmol/liter and ionized calcium from 1.3 to 0.7 mmol/liter. PTH as well as 1,25-(OH)2D3 levels in serum were elevated. Total and ionized calcium levels were normalized within 16 hr after stopping drug treatment. The results showed that foscarnet infusion affects calcium homeostasis and that calcium monitoring might be considered in the clinical use of the drug.

Animals↗