Lucanthone, a Potential PPT1 Inhibitor, Perturbs Stemness, Reduces Tumor Microtube Formation, and Slows the Growth of Temozolomide-Resistant Gliomas In Vivo.

Glioblastoma (GBM) is the most frequently diagnosed primary central nervous system tumor in adults. Despite the standard of care therapy, which includes surgical resection, temozolomide chemotherapy, radiation and the newly added tumor-treating fields, median survival remains only ∼20 months. Unfortunately, GBM has a ∼100% recurrence rate, but after recurrence there are no Food and Drug Administration-approved therapies to limit tumor growth and enhance patient survival, as these tumors are resistant to temozolomide (TMZ). Recently, our laboratory reported that lucanthone slows GBM by inhibiting autophagic flux through lysosome targeting and decreases the number of Olig2+ glioma stem-like cells (GSC) in vitro and in vivo. We now additionally report that lucanthone efficiently abates stemness in patient-derived GSC and reduces tumor microtube formation in GSC, an emerging hallmark of treatment resistance in GBM. In glioma tumors derived from cells with acquired resistance to TMZ, lucanthone retains the ability to perturb tumor growth, inhibits autophagy by targeting lysosomes, and reduces Olig2 positivity. We also find that lucanthone may act as an inhibitor of palmitoyl protein thioesterase 1. Our results suggest that lucanthone may function as a potential treatment option for GBM tumors that are not amenable to TMZ treatment. SIGNIFICANCE STATEMENT: We report that the antischistosome agent lucanthone impedes tumor growth in a preclinical model of temozolomide-resistant glioblastoma and reduces the numbers of stem-like glioma cells. In addition, it acts as an autophagy inhibitor, and its mechanism of action may be via inhibition of palmitoyl protein thioesterase 1. As there are no defined therapies approved for recurrent, TMZ-resistant tumor, lucanthone could emerge as a treatment for glioblastoma tumors that may not be amenable to TMZ both in the newly diagnosed and recurrent settings.

Schistosomiasis chemotherapy.

After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200,000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free-swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies.

Accelerated regression of brain metastases in patients receiving whole brain radiation and the topoisomerase II inhibitor, lucanthone.

PURPOSE: To determine if lucanthone crossed the blood-brain barrier in experimental animals; and to determine accelerated tumor regression of human brain metastases treated jointly with lucanthone and whole brain radiation. METHODS AND MATERIALS: The organ distribution of 3H lucanthone in mice and 125I lucanthone in rats was determined to learn if lucanthone crossed the blood-brain barrier. Size determinations were made of patients' brain metastases from magnetic resonance images or by computed tomography before and after treatment with 30 Gy whole brain radiation alone or with lucanthone. RESULTS: The time course of lucanthone's distribution in brain was identical to that in muscle and heart after intraperitoneal or intravenous administration in experimental animals. Lucanthone, therefore, readily crossed the blood-brain barrier in experimental animals. CONCLUSION: Compared with radiation alone, the tumor regression in patients with brain metastases treated with lucanthone and radiation was accelerated, approaching significance using a permutation test at p = 0.0536.

Overadditive synergism between the intercalators mitoxantrone and lucanthone in advanced L 12010 and P 388 leukemia.

The combination of mitoxantrone with lucanthone, a schistosomicidal and nonmyelotoxic agent, yielded a therapeutic synergism in L 1210 and P 388 leukemia with no increase in toxicity. In that combination the nonmyelotoxic lucanthone enabled the use of the optimal dose of mitoxantrone. The recent hypothesis that planar polycyclic aromatic compounds, mostly comprised by the term intercalators, intercalate with DNA or bind to DNA may need receiving with respect to membrane target sites.

Schistosoma mansoni: an in vivo study of drug-induced autophagy in the gastrodermis.

The effects of Astiban, Lucanthone, Hycanthone and Niridazole on autophagic activities in the gastrodermis of Schistosoma mansoni were determined in vivo, using different dosage levels and dosage times. With Astiban, high levels of autophagy were observed in the gastrodermis 2 hours after an injection of the drug into the mouse, and this response had declined by 20 hours, marking a recovery by the parasite from the drug. Hycanthone and Lucanthone produced an autophagic response several days after the onset of treatment, and no recovery was observed in the morphology of the gastrodermis after the drug was discontinued. The effects of Niridazole on the gastrodermis were to produce the most dramatic ultrastructural changes after high doses and over several days of treatment. With all the drugs examined, gastrodermal autophagy was characterized by the formation of vacuoles containing cell components, lipid droplets and sometimes hydrolytic enzyme reaction product. The autophagic vacuoles appeared to be formed by the sequestration of cytoplasmic material by the basal membrane infoldings, and the transfer of enzymes into the vacuole from within the limiting membrane. The residues from intracellular digestion appeared to be emptied into the caecal lumen.

Aza analogues of lucanthone: synthesis and antitumor and bactericidal properties.

Three types of aza analogues of lucanthone were synthesized for evaluation as antitumor drugs. None of the compounds was found to have significant cytotoxic effects either on Friend tumor cells or on L1210 leukemia cells. However, one of the target compounds, 5,10-dihydro-10-oxo-1-[[3-(diethylamino)propyl]amino]-3-methylpyrido [4,3-b]quinoline, was shown to have noticeable antibiotic properties.

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.

A method for detecting therapeutic activity against Schistosoma mansoni in mice.

A simple and rapid assay, suitable for routine screening against Schistosoma mansoni in mice, can be achieved by using a reduction in the severity of hepatic lesions as the chief criterion of efficacy. Previous attempts to use this criterion were largely hampered by the use of inappropriate time schedules. Provided the timing of treatment and necropsy is restricted to a certain schedule, a mere glance at the opened abdomen of an infected mouse is sufficient to determine whether schistosome reproduction has been suppressed (by chemosterilization or by broader anthelmintic effects). The essence of the necessary schedule is treatment beginning at 4 weeks after infection and prolonged (continuously or intermittently) for 2 weeks, followed by necropsy at 8 weeks after infection. Using the methods described, two persons can easily examine mice for therapeutic response at the rate of 300 per hour. The assay has been shown to detect both schistosomaticidal and chemosterilizing compounds.

Clinically available antischistosomal drugs.

The indications, the contraindications, and the characteristics of the antimonial and nonantimonial drugs clinically available for the treatment of human schistosomiasis are outlined. Of the antimonial compounds, antimony potassium tartrate or antimony sodium tartrate, both given by the intravenous route, are effective against Schistosoma japonicum, S. mansoni, and S. hematobium, but the production of severe side effects limits their use outside the treatment of individuals. Sodium antimonyl gluconate is less effective against S. mansoni and S. hemotobium and is also given intravenously. Of those antimonial compounds given intramuscularly, antimony dimercaptosuccinate is the most effective against all three common human schistosomes. Four available nonmetallic schistosomicides are considered. Niridazole, orally administered, is effective against all three common species of schistosome infecting man, but activity is maximal against S. hematobium. Many minor side effects have been described, but the major and most important side effects, neuropsychiatric symptoms and signs, are fortunately rare. Lucanthone hydrochloride, of moderate efficiency when given orally for S. hematobium or S. mansoni infections, is probably best used as a suppressant in small doses. Troublesome gastrointestinal toxicity limits its therapeutic use. Metrifonate, a cholinesterase-inhibiting organophosphorus compound, is effective only against S. hematobium. Clinical tolerance is very good. Hycanthone mesylate is highly effective against S. mansoni and S. hematobium but ineffective against S. japonicum. It is given as a single intramuscular dose. Many contraindications to its use exist, and acute hepatotoxicity has occurred infrequently. Its association with mutagenicity in certain experimental test systems has stimulated numerous ongoing studies to clarify the implications of its use in humans.

Activity of known antischistosomal agents on early-developing forms of Schistosoma mansoni.

Sixteen compounds, including several series of antischistosomal agents, were tested in mice (subcutaneous, oral, and intramuscular routes), previously injected intraperitoneally with 175 plus or minus 25 Schistosoma mansoni cercariae. Most drugs were given in a 5-day regimen, first dose being administered 3 hr before cercarial inoculation. Ten days after infection the animals were killed, the schistosomules collected from peritoneal washings, and counted under a dissecting microscopy (free organisms and larvae surrounded by macrophages). A high degree of activity (abscess of free larvae) was observed with Hoechst S-616 and S668, Ciba 17,581, Oxamniquine (Pfizer), and RD 12,869 compounds. A significant reduction (P less than 0.05) in the number of larvae was observed with A-16,612, Sb-EDTA, Hycanthone, Schistomide, Trichlorphone, and Antiomaline. No activity on nearly developing forms of S. mansoni was observed after treatment with Mirasan, Hoechst S-201, Schistocide T-109, Lucanthone, and Wellcome 153C51. In conclusion, from 16 compounds taken at random, all of which are active on mature schistosome infections, 11 displayed prophylactic activity. This indicates a high sensitivity of the technique using peritoneal schistosomules.

The adjuvant effect of lucanthone (miracil D) in clinical radiation therapy.

Clinical trials were undertaken to determine whether lucanthone (miracil D) affects radiation-induced regression in measurable pulmonary metastases and advanced squamous-cell oral and pharyngeal tumors. The time required for 50% tumor regression was decreased by approximately 50% in those patients who received lucanthone in addition to irradiation. These results indicate that lucanthone has a definite adjuvant effect when used together with irradiation.