Investigation of the antitumor activity of new epoxide derivatives. Part II: N-glycidylated oxo-nitrogen heterocycles

A number of N-glycidyl compounds derived from oxo-substituted nitrogen heterocycles such as diazines, triazines, diazoles, triazoles as well as condensed ring systems containing these units have been synthesised. All products were tested for their antitumor activity against leukaemia in the mouse. Almost all of the approx. 50 di- and triglycidyl compounds showed activity, whereby 5 of them exhibited an increase of lifespan of 200% and more. The most active compound was 1,2,4-triglycidyl-urazol.

Antineoplastic activity of ASTA Z 7557 (NSC-345842, INN mafosfamide) on transplantable murine tumors

The antitumor activity of ASTA Z 7557, a stabilized primary metabolite of cyclophosphamide, was evaluated in comparison with cyclophosphamide (CP) against different rodent tumor systems. At equimolar doses, which corresponded in mg/kg to the optimal doses of each compound, Z 7557 showed a higher therapeutic activity than CP when both drugs were administered intraperitoneally (ip) during 5 consecutive days. The drug remained active against a P388 subline totally resistant to CP, but to a much lesser extent. The ip-implanted B16 melanoma was highly sensitive to 100 and 50 mg/kg administered during 9 consecutive days: an increase in lifespan (ILS) of 244% was produced and 5 mice out of 10 were cured. This treatment administered against Lewis lung carcinoma (LL) transplanted intravenously (iv) induced an ILS of 179% and 3 mice out of 10 survived on day 60. This effect was slightly inferior to that produced by 50 mg/kg of CP, but is balanced by the number of long-term survivors recorded after administration of low doses of Z 7557. When mice bearing the subcutaneously (sc) implanted colon 38 (C38) tumor were treated with 200 mg/kg on days 2 and 9, the tumor growth was inhibited by 83% in comparison to the control mice. The wide range of activity of Z 7557, its stability and its different chemical reactivity as compared to CP appear to justify interest in this activated oxazaphosphorine.

Investigation of the antitumor activity of new epoxide derivatives. Part I: s-Triazinetrione derivatives

The noteworthy cytostatic activity of triglycidyl-s-triazinetrione and the planned clinical testing of this new active substance induced us to subject this class of substances to closer examination. By chemical reaction of one of the three glycidyl groups present it was possible to introduce wide variations in the properties of the compounds, whilst still retaining the active principle. A number of these substances possessed very high antitumor activity as revealed in the leukemia screening test (P 388; mouse). The influence of other substituents within the glycidyl groups affecting the reactivity of the epoxides groups was also examined.

Regional variations in proliferation rate and degree of differentiation in B16 melanomas

The relationship between proliferation rate and degree of differentiation has been studied in different regions of transplantable B16 melanomas. The regions studied were peripheral parts of the tumours and the inner (perivascular) and outer (external) zones of so-called corded structures. The highest proliferation rates and the poorest cellular differentiation (estimated by volume densities of premelanosomes and melanosomes) occurred in the perivascular zones of corded structures. Conversely, the lowest proliferation rates and the best cellular differentiation was encountered in the external zones of corded structures. Proliferation rates and cellular differentiation in the peripheral parts of the tumours were intermediate between the values obtained in the perivascular or external regions of corded structures. The results in corded structures indicate an inverse relationship between proliferation rate and degree of differentiation, and a positive correlation between proliferative capacity and blood vessel proximity. The intermediate values in the peripheral parts of tumours may reflect the presence of a mixed population of cells which vary in their proximity to the nearest blood vessel.

Iv administration of a water-insoluble antimitotic compound entrapped in liposomes. Preliminary report on infusion of large volumes of liposomes to man

Five patients with advanced multiresistant neoplasms were infused with NSC-251635 (a water-insoluble antimitotic agent) entrapped in egg yolk lecithin, cholesterol, and stearylamine liposomes. The maximum volume injected was 400 ml containing 8 g of lipids, ie, a dose of 135 mg/kg of body weight. Overall tolerance of the treatment was excellent. This study indicates that liposomes may be used safely as carriers for the iv administration of water-insoluble drugs to humans.

Development and characterization of a new murine renal tumor model. Chemotherapeutic results

A murine renal cell carcinoma model, the RC tumor, was pharmacologically and histologically characterized and was used for the evaluation of 20 chemotherapeutic agents. This model, when implanted IP or SC showed reproducible behavior and was found to be very sensitive to many drugs with different mechanisms of action, and particularly to alkylating agents. The IP-implanted tumor was sensitive to some clinically active drugs which were reported inactive against L1210 or P388 murine leukemias. The highest sensitivity of this model than of L1210 and P388 leukemias makes the RC tumor a good prescreening system for testing potential chemotherapeutic agents.

Ineffectiveness of inicarone, a fibrinolytic agent, alone or in combination with chemotherapeutic agents on spontaneously metastasizing murine tumours

The effect of inicarone (L7035), a potent fibrinolytic, alone or in combination, was investigated on spontaneously metastasizing Lewis lung carcinoma (implanted intramuscularly) to verify whether it could prevent the formation of metastases. After intraperitoneal and oral administration, inicarone did not show any cytotoxicity since the survival of animals was not prolonged. Its activity was compared to that of warfarin, an anticoagulant: both drugs were inactive when administered in curative treatment and inicarone even enhanced the number of lung metastases. When administered in combination with cyclophosphamide, an antiproliferative agent, inicarone did not induce any synergism or antagonism, but this combination did not inhibit tumour growth or metastasis spreading. Moreover, when inicarone was combined with a potent antimetastatic agent, Nocodazole, it was shown to be in competition with the latter agent and totally overshadowed its activity; since inicarone had no antimetastatic effect, the number of metastases rose dramatically.

1,3-dipalmitoylglycerol ester of chlorambucil as a lymphotropic, orally administrable antineoplastic agent

A glyceride derivative of chlorambucil (2), 1,3-dipalmitoyl-2-[4-[bis (2-chloroethyl)amino]benzenebutanoyl]glycerol (1), was synthesized and tested as an orally administrable antineoplastic drug endowed with lymphotropic properties. A significantly higher efficacy (increased life span) and a reduced toxicity of 1, relative to 2, were apparent when both compounds given per os were evaluated against P388 leukemia subcutaneously implanted in mice, a situation where the tumor cells disseminate along the lymphatic route. In order to assess the selective absorption of 1 by the intestinal lymphatic system after oral administration, we determined plasma and intestinal lymphatic concentrations and compared them with that obtained with 2. The results clearly demonstrate that the esterification of 2 to a diacylglycerol moiety brings about considerably higher levels in the lymph and reduces plasma levels. Moreover, pharmacokinetic and biological data suggest that 1 is most probably acting by itself rather than as a prodrug of chlorambucil.

Antitumor activity of a water-insoluble compound entrapped in liposomes on L1210 leukemia in mice

The use of sonicated phospholipid vesicles (liposomes) as carriers of 2-[3'-(methoxycarbonylamino)-phenyl]-3-phenyl-6-methoxycarbonylamino-4-(3H)- quinazolone (NSC-251635), a water-insoluble antimitotic compound, was investigated in mice. NSC-251635 was incorporated in egg yolk lecithin, cholesterol, and stearylamine (4:3:1) liposomes. In vitro, NSC-251635 in suspension or entrapped in liposomes was not toxic for L1210 cells. In vivo, after ip or iv injections to CDF1 mice bearing intraperitoneal or intravenous L1210 leukemia, NSC-251635 was active only when it was incorporated in the liposomes and not when it was given as a suspension in Klucel or in saline. The NSC-251635 liposome preparation induced significantly prolonged survival of the treated animals.

Chemotherapeutic efficacy of Nocodazole encapsulated in liposomes on L1210 murine leukemia

The use of sonicated phospholipid vesicles (liposomes) as carriers of methyl [5-(2-thienylcarbonyl)-1H-benzimidazol-2-yl] carbamate (Nocodazole), a water insoluble antimitotic compound active on mouse L1210 leukemia was investigated. Nocodazole was incorporated in dipalmitoyl-phosphatidylcholine: cholesterol: stearylamine (4:3:1) liposomes that were stable at room temperature for at least 48 hr. No drug leakage nor lipid exchange occurred after a 4 hr incubation at 37 degrees C with RPMI 1640 medium supplemented with 10% fetal calf serum. L1210 cells preincubated (2 x 10(6) cells/ml) at 37 degrees C for 3 hr with various concentrations of micronized Nocodazole or liposome-entrapped Nocodazole were injected i.p. into normal CDF1 mice (10(5) cells/mouse). Longest mean survival times and long-time survivors were observed in the group inoculated with L1210 cells preincubated with liposomes containing Nocodazole. CDF1 mice bearing i.p. or i.v. L1210 leukemia were treated i.p. on days 1, 5 and 9 with micronized or liposome-entrapped Nocodazole. Administration of this latter preparation induced a 50% increase in animal life span at the dosage (25 mg/kg/day) half the one required with the free compound (50 mg/kg/day). The present data indicate that enclosing Nocodazole, a water insoluble antimitotic compound, in liposomes results in an enhanced therapeutic activity against L1210 murine leukemia.

Degree of differentiation and blood vessel proximity in B16 melanoma

Corded structures consisting of rows of viable tumour cells around a central blood vessel are present in a number of transplantable mouse tumours, including transplantable B16 melanomas. These tumours were used to assess, by stereological means at the EM level, the range of differentiation of the melanoma cells, according to their position in relation to the central blood vessel. The mitotic index was also determined for perivascular and peripheral tumour cells separately. Furthermore, the transition of peripherally located cells into necrotic tumour cells is described at the EM level. Results shown an important increase in differentiation in peripheral tumour cells, whereas the mitotic index is highest in perivascular cells. Necrotic peripheral cells show features of apoptotic necrosis, together with necrosis of the ischaemic type. Results indicate that both proliferation and differentiation of melanoma cells are related to their position around a central blood vessel, and that peripheral necrosis is not exclusively due to lack of oxygen.

N-methylformamide: antitumour activity and metabolism in mice

The antitumour activities of N-methylformamide, N-ethylformamide and formamide against a number of murine tumours in vivo (Sarcoma 180, M5076 ovarian sarcoma and TLX5 lymphoma) have been estimated. In all cases N-methyl-formamide had significant activity, formamide had marginal or no activity and N-ethylformamide had no significant activity. N-methylformamide and N-ethylformamide were equitoxic to the TLX5 lymphoma in vitro. Formamide was found as a metabolite in the plasma and urine of animals given N-methylformamide and N-ethylformamide, but excretion profiles do not support the hypothesis that formamide is an active antitumour species formed from N-alkylformamides. No appreciable metabolism of N-methylformamide occurred under a variety of conditions with liver preparations in vitro. N-methylformamide, but not N-ethylformamide or formamide, reduced liver soluble non-protein thiols by 59.8% 1 h after administration of an effective antitumour dose.

Successful immunotherapy with micrococcus, BCG or related polysaccharides on L1210 leukaemia after BCNU chemotherapy

The experiments aimed at evaluating the optimal parameters in the chemo-immunotherapeutic treatment of the L1210 lymphoid leukaemia grafted to [female BALB/c (H2d) X male DBA/2 (H2d)]F1 hybrid mice, hereafter referred to as CDF1 mice. In vitro irradiation of leukaemic ascites cells by X- or gamma-rays and subsequent inoculation in mice showed that optimum immunogenicity is radiation dose-dependent. Grafting mice with 10(7) leukaemic ascites cells irradiated at optimum dose (80 GyX- or gamma-rays) delays mortality of the animals when challenged later with untreated L1210 cells, but is unable to cure mice. By contrast, specific immunoprophylaxis induced by Micrococcus, complement-triggering polysaccharides or BCG and irradiated leukaemic cells was able to protect mice against grafts of 10(4) L1210 cells. The i.p. route was notably superior to the i.v. route. When mice bearing advanced L1210 tumour were treated by chemotherapy (12 mg/kg of BCNU) on Day 6.5 after grafting 10(4) L1210 cells and subsequently treated by immunotherapy, a very high percentage (up to 90%) of mice with 10(8) leukaemic cells could be cured by repeated 1mg injections of bacterium or polysaccharide, and challenge with irradiated leukaemic cells was unnecessary. Because of the high cure rate obtained, the very regular response pattern and the non-pathogenicity, the bacterium Micrococcus lysodeikticus would seem a promising new candidate for chemo-immunotherapeutic antitumour strategies.

A characterization of the activity of alpha-1,3,5-triglycidyl-s-triazinetrione, a novel antineoplastic compound

To extend initial results on the antineoplastic activity of alpha-1,3,5-triglycidyl-s-triazinetrione (TGT, NSC 296934), a novel triepoxidic derivative, this compound was tested in a series of murine transplantable tumors. Repeated daily treatments with well-tolerated systemic doses of this chemical produced substantial retardation in tumor growth and significant prolongation of survival in the line 16 mammary, M5067 ovarian, and Madison 109 lung carcinomas and in mFS6 fibrosarcoma. Very marked activity was also seen in the P815 mastocytoma, B16 melanoma, line 38 colon carcinoma, and an intracerebrally transplanted ependymoblastoma, with high proportions of cures after one or two injections in IP transplanted SL2 lymphoma and line 26 colon carcinoma. It is concluded that the high level of antineoplastic effectiveness and the wide spectrum of TGT activity together with its novel structural characteristics could be of clinical significance.

Investigations into the antitumour activity of organotin compounds. I. Diorganotin dihalide and di-pseudohalide complexes

The antitumor activity of a series of diorganotin dihalide and di-pseudohalide complexes, R2SnX2, L2, where R = Methyl (Me), Ethyl (Et), n-Propyl (Pr), n-Butyl (Bu) or Phenyl (Ph); X = F, Cl, Br, I or NCS; and L = O- or N- donor organic ligand, which were modelled on the active platinum complexes, has been investigated. A number of these derivatives exhibit reproducible therapeutic activity in vivo towards P-388 lymphocytic leukaemia in mice, particularly the diethyltin dihalide and dipseudohalide complexes. The possible factors influencing activity are discussed, both in terms of the stereochemistry of the dialkyltin compounds and their structural similarity to the platinum antitumour drugs.

Influence of micrococcus, BCG and related polysaccharides on the proliferation of the L1210 leukaemia

A comparative study of the effects of BCG, Micrococcus lysodeikticus, and a series of structurally related polysaccharides (complement triggers) on the non-specific and specific immune resistance against L1210 lymphoid leukaemia was carried out and commented on. In contrast with authors of earlier reports, we were unable to generate any effective non-specific or specific immunotherapy after the graft of 10(4) leukaemic cells to 8--10-week-old CDF1 mice. However, when mice were prevaccinated with irradiated (8 krad X-rays) cultured cells combined with 1 mg of bacterium or polysaccharide one month before grafting 10(4) cells, they were given an immunoprotection that was more pronounced with the i.p. than with the i.v. route. Prevaccinated mice were afforded a stronger immunoprotection when boosted repeatedly with 1mg injections of bacterium or polysaccharide after tumour challenge.

Potentiation of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea by amphotericin B in murine ependymoblastoma

This paper reports the potentiation of the therapeutic effect of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) by amphotericin B (AMB) in s.c. transplanted murine ependymoblastoma 01B111. The rate of 2-month cures was 6% when tumors were treated 10 to 12 days after transplantation by a single 6 i.m. injection of 2.5 mg of CCNU per kg and reached 15% with 10 mg of CCNU per kg. When 25 mg of AMB per kg were given i.p. 10 hr prior to CCNU, the respective figures increased to 18 and 58%, the differences being significant at 5 and 1%. A single dose of 25 mg of AMB per kg given alone did not affect tumor growth. Radioactivity per g of tumor was measured 30, 60, and 120 min after injection of [14C]CCNU in total tissue, chloroform:methanol (2:1, v/v) extract, and CCNU isolated by thin-layer chromatography. No difference was found between animals treated with 25 mg of AMB per kg and controls. The inhibition of DNA synthesis, measured 24 hr after the administration of CCNU and 2 hr after the injection of [3H]thymidine, was almost optimal with 5 mg of CCNU per kg. The inhibition caused by 1 mg of CCNU per kg was not enhanced by AMB. Thus, the potentiation of CCNU by AMB does not seem attributable to an increased permeability of the tumor to CCNU or to an enhancement of the inhibition of DNA synthesis, at least in murine ependymoblastoma.