Evaluation of external-beam radiation therapy plus 5-fluorouracil (5-FU) versus external-beam radiation therapy plus hycanthone (HYC) in confined, unresectable pancreatic cancer.

From March 1981 to November 1987, 87 patients with histologically confirmed pancreatic adenocarcinoma, unresectable but confined to the pancreatic region, were randomized to two treatments. The standard treatment was 40-50 Gy external-beam radiation therapy (RT) to gross tumor plus potential microscopic tumor with a 5 Gy boost to gross tumor plus a 1.5-2.0 cm margin, using multiple fields and 5-fluorouracil (5-FU) 500 mg/m2/d intravenously by rapid infusion. The 5-FU was given each of the initial 3 days of each of three 20 Gy radiation courses. The experimental treatment used identical radiation fields, but the two Gy daily radiation fractions were administered in a continuous course to a total dose of 50 Gy. Hycanthone was administered 60 mg/m2 intravenously within 2 to 4 hr during each day of the 5-day course of infusions during the first and fifth weeks of radiation therapy. There was no statistically significant difference between treatment arms in survival (p = 0.82) or disease-free survival (p = 0.27). Seven percent of hycanthone-treated patients demonstrated hepatic toxicity which was usually mild in nature. There was, however, one death due to hepatic toxicity.

Analogues of hycanthone and lucanthone as antitumor agents.

Hycanthone analogues (5 and 6) containing 7-substituted hydroxyl groups were prepared and evaluated as antitumor agents. These compounds were significantly more active than the corresponding unsubstituted derivatives. The 7-hydroxylated 4-(hydroxymethyl)-9H-xanthen-9-ones, 11 and 12, were also active antitumor agents. However, the 7-hydroxy-9H-xanthen-9-one counterparts of the 7-hydroxylucanthones were totally devoid of antitumor activity. Results obtained thus far are consistent with the hypothesis that 4-hydroxymethyl substituents in the 9H-xanthen-9-one and 9H-thioxanthen-9-one series are required for antitumor activity.

Preparation and antischistosomal and antitumor activity of hycanthone and some of its congeners. Evidence for the mode of action of hycanthone.

The synthesis of a series of esters of hycanthone (HC) and 7-hydroxyhycanthone, their antitumor activity, and their antischistosomal effects on HC-sensitive and HC-resistant schistosomes are reported. Binding studies using tritium-labeled HC and hycanthone N-methylcarbamate (HNMC) with calf thymus DNA provided evidence that HNMC but not HC alkylated the DNA. Tritiated HNMC also bound to the DNA of intact HeLa cells exposed to the drug while very little tritiated HC bound to DNA under the same conditions. The mechanism proposed previously to account for the antischistosomal action of HC, namely, drug esterification followed by alkylation of DNA, applies also to the antitumor action of the drug as shown in Scheme I.

Susceptibility to chemotherapeutic agents of strains of Schistosoma mansoni isolated from treated and untreated patients.

Seven strains of Schistosoma mansoni were isolated from the feces of patients. Three of the patients had been unsuccessfully treated with hycanthone or oxamniquine; the remaining four had not been given any specific treatment. Mice infected with these strains were treated 45 days later with niridazole (50 or 100 mg/kg body weight per day for 5 days, per os), hycanthone (single dose of 80 or 160 mg/kg, intramuscularly), or oxamniquine (single dose of 50 or 100 mg/kg, per os). Significant differences in the strains' responses to the schistosomicidal agents used were observed. Oogram changes in mice treated with the same drug ranged from 10--100%, and percentages of dead worms from 0--45. Such differences seemed to be dependent on the strain's specific characters rather than t their having been exposed to schistosomicidal drugs.

Comparative effects of hycanthone in Schistosoma mansoni and Schistosoma japonicum.

After in vitro hycanthone treatment followed by a 20-hour incubation in drug-free medium, Schistosoma mansoni were still resistant to labeling by a fluorescent analog of acetylcholine. S. japonicum, in contrast with the hycanthone sensitive species, showed prompt reversal of the blocking effects of hycanthone on fluorescent labeling. This finding suggests that differences in the reversibility of hycanthone may correlate with the usefulness of the drug in the therapy of schistosome infections by different species of parasites. Scanning electron microscopy has been used to demonstrate that hycanthone treatment causes degeneration of the integument of S. mansoni, but not S. japonicum, over a period of few days after in vivo exposure to hycanthone. The mechanism by which hycanthone causes this effect is not known.

Curative chemotherapy and resistance to reinfection in murine schistosomiasis.

Complete parasitological cure was obtained by specific chemotherapy in mice with a 10-week-old infection induced by inoculating 30 cercariae of Schistosoma mansoni. By challenging the cured animals with 100 cercariae it was found that cutaneous and pulmonary reactivity to invading schistosomula, the ability to modulate periovular granulomas in the liver, and the resistance to reinfection, as measured by survival rates and recovery of worms from the portal vein system, persisted for 1 and 2 months following treatment and disappeared after 6 months. Thus, a residual immunity and reactivity to reinfection seems to persist in the host for some time after curative chemotherapy of schistosomiasis.

Hycanthone dose-response in treatment of schistosomiasis mansoni in St. Lucia.

Clinical trials of hycanthone (single intramuscular dose) were undertaken in schistosomiasis mansoni patients in St. Lucia at five dose levels: 3.0, 2.5, 2.0, 1.5, and 1.0 mg/kg body weight. The most common side effect, vomiting, decreased in frequency from 51% at the highest dose to 3% at the lowest; minor side effects showed a similar trend. Three fecal specimens were examined before and at 6 months after treatment by qualitative, quantitative, and hatching techniques. All dose levels caused reductions in egg excretion of 89 to 98%. Rates of cure (absence of eggs by all three methods) according to dose (descending), pretreatment egg output (0-19, 20-49, 50-399, 400+ eggs/ml feces), and age (0-7, 8-14, 15-29, 30+ years) were analyzed to estimate the effect of each variable if the others had been constant. For dose, the standardized percentage success rates were 53.9%, 62.0%, 51.2% 54.0%, and 27.4%; for egg output, 67.0%, 51.8%, 43.2%, and 21.7%; and for age, 25.2%, 34.5%, 59.3% and 57.4%. Logit regression analysis shows a significant difference in cure rate (a) between the lowest dose and all others, among which latter there was no difference, (b) between patients excreting 0 to 49 eggs/ml before treatment and those excreting 50+ eggs/ml, and (c) between the age groups 0 to 14 and 15+ years. All dose levels caused some regression in enlargement of liver or spleen. A dose of 1.5 to 2.0 mg/kg body weight is considered to be as effective as one of 3.0 mg/kg and more acceptable for a control program because of the marked reduction in side effects.

Genetic analysis of hycanthone resistance in Schistosoma mansoni.

Interbreeding between hycanthone-resistant and hycanthone-sensitive schistosomes was achieved using a worm transfer technique which considerably reduced the length and the complexity of the operations generally involved in performing schistosome genetic crosses. A mouse was considered to harbor resistant schistosomes if, three weeks or more after a single intrasmuscular injection of 80 mg/kg hycanthone schistosome eggs were still excreted in the feces, at least one normal worm pair was obtained by perfusion, or miracidia could be seen hatching from the liver. The F1 hybrid progeny from crosses between sensitive and resistant schistosomes proved to be sensitive to hycanthone, irrespective of whether the resistant parent was the male or the female. The resistant phenotype reappeared in back-crosses and in the F2 progeny. These results could be confirmed using the traditional technique of single sex infections. It can thus be concluded that hycanthone resistance behaves like an autosomal recessive trait. These results suggest that hycanthone-resistant schistosomes are deficient in some factor, possibly an enzymatic activity which transforms hycanthone into a biologically active molecule, as suggested in a recent hypothesis on the mode of action of hycanthone.

A study of the mode of action of hycanthone against Schistosoma mansoni in vivo and in vitro.

Schistosomes obtained by perfusion from host animals as early as 2 hours after in vivo treatment with hycanthone and transferred into untreated recipient hamsters died in the recipient host. In contrast, unexposed schistosomes transferred into recipient hamsters treated from 7 days to 36 hours previously showed a normal survival. In vitro treatment of schistosomes with hycanthone concentrations comparable to those used in in vivo studies, followed by transfer of the parasites into normal hamsters, resulted in death of the worms. The time of lethal hycanthone exposure in vitro could be as short as 15 minutes. Hycanthone-resistant schistosomes or immature worms were not affected under similar in vitro conditions. Our data suggest that the schistosomicidal effect of hycanthone is not caused by a host-derived metabolite.

Control of Schistosoma mansoni transmission by chemotherapy in St. Lucia. I. Results in man.

Control of Schistosoma mansoni transmission solely by treatment of all infected persons was attempted in Marquis Valley (population about 3,100), St. Lucia. Two-year results are reported. Excluding 26 pregnant patients, 709 to 729 persons who were found to be infected received treatment the first year. Most of these, 677, were given a single injection of hycanthone (2.5 mg/kg of body weight), and the same treatment was administered to 159 patients the second year. Side effects were not severe; the major side effect, vomiting, occurred in about 22% on both occasions. In villages with initially high transmission rates, the incidence of new infections in children 0 to 14 years fell from 20.8% before chemotherapy to 7.4% after 1 year and to 3.7% after 2 years. This pattern was significantly different from that in the comparison area where no control scheme exists. Chemotherapy alone appears to be a rapid, effective, and comparatively inexpensive method of controlling S. mansoni transmission in St. Lucia.

Effect of chemotherapy on experimental pulmonary schistosomiasis.

Mice with portal hypertension caused by portal vein ligation reproduced the model of severe pulmonary schistosomiasis when infected for 10 weeks with 30 cercariae of Schistosoma mansoni. Curative treatment promoted reversion, without fibrosis, of the periovular granulomatous lesions formed in the alveolar tissue. However, the arterial and arteriolar lesions were defectively repaired, with segmental vascular fibrosis, narrowing, and angiomatoid changes remaining for up to 120 days after treatment. There was also evidence that eggs are destroyed more rapidly and more completely in the lungs than in the liver.

The activity of a benzothiopyranoindazole (IA-4 N-oxide) against Schistosoma mansoni infection in rhesus monkeys.

The prophylactic and therapeutic efficacies of IA-4 N-oxide against Schistosoma mansoni in rhesus monkeys (Macaca mulatta) have been evaluated. Ten monkeys were divided into 5 groups of 2 monkeys each. All monkeys were exposed to S. mansoni cercariae on day 0 and treatment groups were established as follows: untreated controls, oral prophylactic administration, intramuscular prophylactic administration, oral therapeutic administration, and intramuscular therapeutic administration. Analysis of parasitologic and pathologic criteria indicate that the compound is most effective when administered as a therapeutic regimen. Complete cures were effected in these monkeys. Prophylactic treatments resulted in a delay in onset of patency and reductions in fecal egg excretion, worm burdens, and tissue damage.

A note on drug trials in schistosomiasis.

In schistosomiasis, if the subjects of drug trials are in contact with potentially contaminated water, then differences in the chemotherapeutic response to the same dose of a drug given in the same endemic area in different seasons, may be related to different levels of transmission. Because a reduction in egg excretion may occur from causes other than chemotherapy, moderate antischistosomal activity of a drug cannot be concluded in the absence of a control group.

Effect of chemotherapy on hepatic collagen and glycosaminoglycan metabolism in Schistosoma mansoni-infected mice.

The dynamics of biosynthesis and accumulation of collagenous proteins and glycosaminoglycans (GAGs) in liver granulomas induced by eggs of Schistosoma mansoni were studied in mice following eradication of adult worms by chemotherapy. The relatively synchronous granulomas around parasite eggs were isolated from the livers at ensuing 2-week intervals; the number of recoverable granulomas per liver gradually decreased and was 7% of initial values at 20 weeks. Hepatic or granuloma-associated extracellular matrix components increased for 4 weeks after treatment despite cessation of ova deposition. At 12 weeks after chemotherapy the rate of GAG biosynthesis per total liver granuloma fraction, measured by 3H-glucosamine incorporation, decreased dramatically; this was followed by a decrease in the amount of GAGs present. The rate of collagen biosynthesis per total liver granuloma fraction, measured by 3H-proline incorporation, began to decline at 14 weeks and a decrease in the amount of collagen present was noted at 16 weeks. Our results demonstrated that liver granulomas induced by S. mansoni eggs synthesize collagens and GAGs for about 4-6 weeks following parasitological cure. The subsequent resolution of granulomas proceeds first by a reduction in GAG biosynthesis followed 4-8 weeks later by decreased collagen biosynthesis, followed by accelerated resolution of both collagen and GAGs.

Observations on possible immunity to reinfection among Kenyan schoolchildren after treatment for Schistosoma mansoni.

In February 1977, 306 out of 409 six- to 16-year-old Kenyan schoolchildren were found to be infected with Schistosoma mansoni. Prevalence and intensity were directly related to age and indirectly to the distance between the child's home and the transmission site, but were not related to the child's sex. Most children were treated with hycanthone in July 1977. Pretreatment blood samples were taken from 100 study children for eosinophil counts and measurements of cytotoxic anti-schistosomular antibody levels. Blood and faecal samples were re-examined five times between November 1977 and July 1979. Whole school resurveys in July 1978 and 1979 confirmed the continuation of transmission after chemotherapy. 'Reinfection' rates in the study children, incorporating both failed treatment and true reinfections, were significantly reduced in children, with both detectable antibody and eosinophil counts above 400/mm3, compared with children with neither. Children with either detectable antibodies or high eosinophil counts (mainly the latter) had intermediate reinfection rates. Neither sex, age nor pretreatment intensities influenced reinfection rates, but location of dwelling did: children from distant homes had lower rates. However, the effects of residence and 'protection' were not directly linked. The implication of these results, namely that infection can confer immune protection to reinfection after treatment, is being explored in further studies.

Schistosoma mansoni control in Cul de Sac Valley, Saint Lucia. II. Chemotherapy as a supplement to a focal mollusciciding programme.

After an intensive area-wide mollusciciding campaign, over four and a half years, transmission of Schistosoma mansoni was reduced. A cheaper scheme suitable for the follow-up or consolidation stage of control was evaluated and two selective population chemotherapy campaigns using hycanthone (2 mg/kg b.w.) and oxamniquine (15 mg/kg b.w.) were mounted. Prevalence dropped to 6% and 3% in areas with previously high and low levels of transmission respectively. Calculations suggested that these figures were falsely low and that perhaps 20% of the population were still excreting S. mansoni ova in small numbers. The unco-operative groups in the population are probably more important in maintaining a reservoir of infection in the community than persons with light infections undetected by the sedimentation concentration stool examination technique used. The benefit of more sensitive but more costly examination techniques is not clear since the importance of very light infections in transmission is uncertain. Case detection absorbs an increasing proportion of the total cost of chemotherapy programmes with fewer cases being found amongst the same number screened. Using hycanthone (649 treated) the cost per person protected was $0.74 and using oxamniquine (264 treated) $0.94. The need to develop low cost consolidation or follow-up procedures for preventing a resurgence of transmission after successful control, when the infection is no longer of public health importance, is stressed.

Use of praziquantel in patients with schistosomiasis mansoni previously treated with oxamniquine and/or hycanthone: resistance of Schistosoma mansoni to schistosomicidal agents.

Fourteen patients with active schistosomiasis mansoni in spite of previous treatment with oxamniquine and/or hycanthone were treated with praziquantel, single oral dose of 45 to 50 mg/kg body-weight. All underwent clinical, laboratory and electrocardiographic examination before and after treatment. Untoward effects (dizziness, drowziness, nausea and abdominal pain) were observed in ten. Laboratory findings disclosed no significant alteration and the electrocardiograms showed no abnormalities. Monthly follow-up examinations of 13 patients for six consecutive months showed parasitological cure in all. Before praziquantel treatment strains of Schistosoma mansoni were isolated from two patients, one treated three times with oxamniquine and the other with hycanthone once and oxamniquine twice. Progenies of these strains were maintained in Biomphalaria glabrata and mice. Groups of these infected mice were then treated with oxamniquine, hycanthone, niridazole and praziquantel and results compared with the BH strain maintained in our laboratory for many years. Schistosomicidal activity was assessed by the localization of worms in the portal vein system and oogram changes. Progenies from the strains isolated in this study were resistant to oxamniquine and hycanthone but sensitive to niridazole and praziquantel. The BH strain was sensitive to all four drugs. The serial runs of S. mansoni strains through intermediate and definitive hosts have not influenced their reactions to these schistosomicides.

Drug resistance to schistosomicides and other anthelmintics of medical significance.

It is usual for people to be infected for some period in life with parasitic worms, which may cause morbidity or even kill. Anthelmintics are used for the treatment and control of the human helminthiases, since no vaccines are yet available. Despite the widespread use of these compounds, drug resistance has become apparent only with antischistosomal chemotherapy, in contrast to the situation with other anti-infective agents in human medicine and with veterinary anthelmintics, where resistance is widespread. This paper reviews research on drug resistance in human helminthiasis with emphasis on schistosomicidal drugs.

Synthesis of new 8-(5-substituted amino-1,3,4-oxadiazol-2-yl) and 8-(5-substituted amino-1,3,4-thiadiazol-2-yl) methoxyquinolines with antibilharzial activity.

Several 5-substituted amino-1,3,4-oxadiazol-2-yl and 5-substituted amino-1,3,4-thiadiazol-2-yl derivatives with different 8-hydroxyquinoline moieties in the 2-position were prepared and tested for their antiparasitic activity. Preliminary biological tests on mice experimentally infested with Schistosoma mansoni revealed that the new compounds show moderate schistosomicidal activity.

The influence of anti-parasitic therapy on the course of the glomerulopathy associated with Schistosomiasis mansoni.

Although several aspects of the association between S. mansoni infection and renal disease are well known, the influence of the anti-parasitic therapy on the clinical course of the glomerulopathy remains undefined. With the aim of studying this aspect, 16 patients with glomerulopathy associated with schistosomiasis mansoni were evaluated (proteinuria and levels of BUN and creatinine) before therapy, 1 week, 1 month, 2-3 months and 6 months after therapy of the parasitic infections. During the follow-up of such cases no benefit could unquestionably be demonstrated in the patients. Also, no permanent deterioration of renal function related to anti-parasitic therapy could be documented. It is concluded that the treatment of the S. mansoni infection, once the consequent glomerulopathy is clinically apparent, does not influence the clinical course of the disease.