Four years' experience of melarsen oxide/BAL in the treatment of late-stage Rhodesian sleeping sickness

Chemotherapy for second-stage human African trypanosomiasis

BACKGROUND

Human African trypanosomiasis, or sleeping sickness, is a painful and protracted disease affecting people in the poorest parts of Africa and is fatal without treatment. Few drugs are currently available for second-stage sleeping sickness, with considerable adverse events and variable efficacy.

OBJECTIVES

To evaluate the effectiveness and safety of drugs for treating second-stage human African trypanosomiasis.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register (January 2013), CENTRAL (The Cochrane Library Issue 12 2012) , MEDLINE (1966 to January 2013), EMBASE (1974 to January 2013), LILACS (1982 to January 2013 ), BIOSIS (1926-January 2013), mRCT (January 2013) and reference lists. We contacted researchers working in the field and organizations.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials including adults and children with second-stage HAT, treated with anti-trypanosomal drugs.

DATA COLLECTION AND ANALYSIS

Two authors (VL and AK) extracted data and assessed methodological quality; a third author (JS) acted as an arbitrator. Included trials only reported dichotomous outcomes, and we present these as risk ratio (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Nine trials with 2577 participants, all with Trypansoma brucei gambiense HAT, were included. Seven trials tested currently available drugs: melarsoprol, eflornithine, nifurtimox, alone or in combination; one trial tested pentamidine, and one trial assessed the addition of prednisolone to melarsoprol. The frequency of death and number of adverse events were similar between patients treated with fixed 10-day regimens of melarsoprol or 26-days regimens. Melarsoprol monotherapy gave fewer relapses than pentamidine or nifurtimox, but resulted in more adverse events.Later trials evaluate nifurtimox combined with eflornithine (NECT), showing this gives few relapses and is well tolerated. It also has practical advantages in reducing the frequency and number of eflornithine slow infusions to twice a day, thus easing the burden on health personnel and patients.

AUTHORS' CONCLUSIONS

Choice of therapy for second stage Gambiense HAT will continue to be determined by what is locally available, but eflornithine and NECT are likely to replace melarsoprol, with careful parasite resistance monitoring. We need research on reducing adverse effects of currently used drugs, testing different regimens, and experimental and clinical studies of new compounds, effective for both stages of the disease.

Safety and efficacy of the 10-day melarsoprol schedule for the treatment of second stage Rhodesiense sleeping sickness

OBJECTIVE

Assessment of the safety and efficacy of a 10-day melarsoprol schedule in second stage T.b. rhodesiense patients and the effect of suramin-pretreatment on the incidence of encephalopathic syndrome (ES) during melarsoprol therapy.

DESIGN

Sequential conduct of a proof-of-concept trial (n = 60) and a utilization study (n = 78) using historic controls as comparator.

SETTING

Two trial centres in the T.b. rhodesiense endemic regions of Tanzania and Uganda.

PARTICIPANTS

Consenting patients with confirmed second stage disease and a minimum age of 6 years were eligible for participation. Unconscious and pregnant patients were excluded.

MAIN OUTCOME MEASURES

The primary outcome measures were safety and efficacy at end of treatment. The secondary outcome measure was efficacy during follow-up after 3, 6 and 12 months.

RESULTS

The incidence of ES in the trial population was 11.2% (CI 5-17%) and 13% (CI 9-17%) in the historic data. The respective case fatality rates were 8.4% (CI 3-13.8%) and 9.3% (CI 6-12.6%). All patients discharged alive were free of parasites at end of treatment. Twelve months after discharge, 96% of patients were clinically cured. The mean hospitalization time was reduced from 29 to 13 days (p<0.0001) per patient.

CONCLUSIONS

The 10-day melarsoprol schedule does not expose patients to a higher risk of ES or death than does treatment according to national schedules in current use. The efficacy of the 10-day melarsoprol schedule was highly satisfactory. No benefit could be attributed to the suramin pre-treatment.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN40537886.

Chemotherapy for second-stage Human African trypanosomiasis

BACKGROUND

Human African trypanosomiasis, or sleeping sickness, is a painful and protracted disease affecting people in the poorest parts of Africa and is fatal without treatment. Few drugs are currently available for second-stage sleeping sickness, with considerable adverse events and variable efficacy.

OBJECTIVES

To evaluate the effectiveness and safety of drugs for treating second-stage human African trypanosomiasis.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (May 2010), CENTRAL (The Cochrane Library Issue 3 2010) , MEDLINE (1966 to May 2010), EMBASE (1974 to May 2010), LILACS (1982 to May 2010 ), BIOSIS (1926-May 2010), mRCT (May 2010) and reference lists. We contacted researchers working in the field and organizations.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials.

DATA COLLECTION AND ANALYSIS

Two authors (VL and AK) extracted data and assessed methodological quality; a third author (JS) acted as an arbitrator. Included trials only reported dichotomous outcomes, and we present these as risk ratio (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Nine trials with 2577 participants, all with Trypansoma brucei gambiense HAT, were included. Seven trials tested currently available drugs: melarsoprol, eflornithine, nifurtimox, alone or in combination; one trial tested pentamidine, and one trial assessed the addition of prednisolone to melarsoprol. Fixed 10-day regimens of melarsoprol were found to be as effective as those of 26 days, with similar numbers of adverse events. Melarsoprol monotherapy gave fewer relapses than pentamidine or nifurtimox, but resulted in more adverse events.Later trials evaluate nifurtimox combined with eflornithine (NECT), showing this gives few relapses and is well tolerated. It also has practical advantages in reducing the burden on health personnel and patients, when compared to eflornithine monotherapy.

AUTHORS' CONCLUSIONS

Choice of therapy for second stage Gambiense HAT will continue to be determined by what is locally available, but eflornithine and NECT are likely to replace melarsoprol, with careful parasite resistance monitoring. We need research on reducing adverse effects of currently used drugs, testing different regimens, and experimental and clinical studies of new compounds, effective for both stages of the disease.

Effective measures for controlling trypanosomiasis

African trypanosomiasis, otherwise known as sleeping sickness in humans and 'Nagana' in cattle, is a disease that is resurgent in Africa. Research on the disease suggests that the development of a vaccine is still far away; even existing drugs are becoming ineffective on account of the emergence of drug-resistant trypanosomes. All this contributes to heavy economic losses and a sociopolitical crisis in the continent, thus underscoring the pressure to intensify research for inexpensive, less toxic and affordable trypanocides. This review discusses the current treatment of trypanosomiasis and the progress made towards the effective control of trypanosomiasis.

Treatment perspectives for human African trypanosomiasis

Human African trypanosomiasis (HAT), or sleeping sickness, is currently on the rise. HAT develops in two stages, the first involving the hemolymphatic system, and the second, the neurological system. Left untreated, HAT is invariably fatal. There have been no therapeutic advances in more than 40 years. Stage 1 can be treated with pentamidine and suramin, but stage 2 can only be treated with melarsoprol, a toxic arsenic derivative that has a 2-12% incidence of fatal side-effects (encephalopathy). Eflornithine has never achieved widespread use because it is difficult to administer under field conditions. Nifurtimox has been used successfully in the treatment of American trypanosomiasis, or Chagas disease, but only in small studies or as a compassionate use treatment. There is little research and development for new drugs in this area: only one prodrug is in the clinical development phase, a pentamidine analog that offers hope for the replacement of injectable pentamidine with an orally administered drug. Current efforts appear to be focused on reevaluating older drugs. A course of treatment with melarsoprol for 10 days at 2.2 mg/kg/day is now in the multicenter evaluation phase. Orally administered eflornithine is also slated for reevaluation. In addition, studies of drug combinations are recommended to determine possible combined or synergistic effects and find ways to reduce toxicity.

The curative power of 4-(2:6-diaminopyrimidin-4-ylamino) phenylarsine oxide (compound 12,065) in infections of Trypanosoma rhodesiense in laboratory animals

The toxicity to laboratory animals of 4-(2:6-diaminopyrimidin-4-ylamino)phenylarsine oxide (compound 12,065), and its ability to cure laboratory infections of Trypanosoma rhodesiense were investigated. The intramuscular LD50 to mice was 22 mg./kg.; rats were more susceptible. Monkeys tolerated two daily doses of 6 mg./kg., but not two daily doses of 10 mg./kg. The intramuscular CD50 to mice was about 6 mg./kg. with two strains of T. rhodesiense recently isolated from human patients, and 2 mg./kg. with a strain of T. rhodesiense which had been maintained by cyclical transmission through tsetse flies in the laboratory for about 17 months. These results are compared with those reported by Ainley and Davey (1958) for a strain of T. rhodesiense which had been maintained in the laboratory by cyclical transmission for about 12 years and then by syringe transmission for about 10 years. The syringe-transmitted strain was at least 20 times more susceptible to the drug than the recently isolated strains. The potencies of compound 12,065 and melarsen oxide/BAL in curing T. rhodesiense infections in mice were compared: the CD50 for compound 12,065 was 6.5 mg./kg. and for melarsen oxide/BAL was 3.7 mg./kg. The ratios LD50/CD50 for the drugs were about 4 and 6 respectively.

Risk factors for encephalopathy and mortality during melarsoprol treatment of Trypanosoma brucei gambiense sleeping sickness

This paper reviews the incidence of, and risk factors for, drug-induced encephalopathy and mortality (from all causes) during treatment with melarsoprol of 1083 patients with Trypanosoma brucei gambiense sleeping sickness in Nioki hospital (Zaire) between 1983 and 1990. Sixty-four patients (5.9%) developed encephalopathy and 62 (5.7%) died: 43 from reactive encephalopathy and 19 from other causes. Univariate and multivariate analyses showed that the administration of prednisolone reduced significantly the incidence of encephalopathy and mortality during treatment, especially in patients with trypanosomes observed in the cerebrospinal fluid (CSF) and/or with a CSF white blood cell (WBC) count of 100 or more per mm3. The risk of encephalopathy was associated more strongly with the CSF WBC count than with the presence of CSF trypanosomes. In the subgroup of patients with a CSF WBC count of 100 or more mm3, changing the melarsoprol regimen to 3 series of 3 injections instead of 3 series of 4 injections halved the mortality rate during treatment. Treatment of patients who do develop reactive encephalopathy with the heavy metal chelator dimercaprol, in addition to intravenous steroids and anticonvulsants, may be harmful. The data suggest that a further reduction of the total dose of melarsoprol may decrease toxicity without jeopardizing efficacy.

Gambiense trypanosomiasis: frequency of, and risk factors for, failure of melarsoprol therapy

1083 patients with late-stage Trypanosoma brucei gambiense sleeping sickness were treated with melarsoprol in Nioki hospital, Zaire, between 1983 and 1990. Sixty-two (5.7%) died during treatment. Of the 1021 patients who survived the treatment, 63 (6.2%) subsequently relapsed, 58 (92%) of whom were diagnosed within 2 years of melarsoprol treatment. There was no evidence of an increase in the frequency of treatment failures during the study period, and the rate of relapses that we documented is comparable to that reported from Zaire more than 30 years ago. Relapses were more frequent among patients who had trypanosomes seen in the cerebrospinal fluid (CSF) at the time of the initial diagnosis (odds ratio [OR] = 2.76, 95% confidence interval [CI] = 1.65-4.63, P = 0.0001). Male patients had twice as many relapses as females (OR = 2.00, 95% CI = 1.19-3.36, P = 0.009), which was partly explained by males having trypanosomes in the CSF more often than females. There were important geographical variations in the frequency of relapses within the territory of the Nioki rural health zone, suggesting that the circulation of trypanosomes was geographically limited. Prednisolone treatment did not increase the risk of treatment failure, nor did decreasing the total dose of melarsoprol from 12 to 9 injections for patients with > or = 100 white blood cells/mm3 of CSF. Since patients with trypanosomes in the CSF are also those who are at the highest risk of melarsoprol-induced encephalopathy, more aggressive treatment regimens cannot be recommended.(ABSTRACT TRUNCATED AT 250 WORDS)