Apoptosis inducing novel anti-leukemic agent, bis(4,7-dimethyl-1,10 phenanthroline) sulfatooxovanadium(IV) [VO(SO4)(Me2-Phen)2] depolarizes mitochondrial membranes

Bis(4,7-dimethyl-1,10 phenanthroline) sulfatooxovanadium(IV) [VO(SO(4) )(Me(2)-Phen)(2)] induces apoptosis in human NALM-6 leukemia cells. In the present report, we demonstrate that VO(SO(4) )(Me(2)-Phen)(2)-induced apoptosis is mediated through the generation of reactive oxygen species (ROS), depletion of glutathione and depolarization of mitochondrial membrane potential (DeltaPsim). Using multilaser flow cytometry methods, we further mapped out the death sequence that occurs in VO(SO(4))(Me(2)-Phen)(2)-treated leukemic cells. Triple labeling method to measure ROS, DeltaPsim and glutathione coupled with multilaser excitation flow cytometry showed that induction of ROS took place before the loss of mitochondrial permeability transition and depletion of glutathione. Correlated two parameter plots of glutathione content versus DeltaPsim showed that loss of DeltaPsim and depletion of glutathione closely follows each other. Translocation of phosphatidylserine to the outer leaflet of the cell membrane was the final step in the process before the cells became apoptotic. These results demonstrate that the mitochondrial permeability transition takes place during VO(SO(4))(Me(2)-Phen)(2)-induced apoptosis and is mediated through induction of ROS and depletion of glutathione.     

Bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(IV) as a novel apoptosis-inducing anticancer agent.

In a systematic effort to identify a potent anticancer agent, we synthesized 15 oxovanadium(IV) complexes and examined their cytotoxic activity against 14 different human cancer cell lines. The oxovanadium compounds included mono and bis ancillary ligands of 1,10-phenanthroline (phen) [VO(phen), VO(phen)2, VO(Me2-phen), VO (Me2-phen)2, VO(Cl-phen), VO(Cl-phen)2, VO(NO2-phen), VO(NO2-phen)2], 2,2'-bipyridyl (bipy) [VO(bipy), VO(bipy)2, VO(Me2-bipy), VO(Me2-bipy)2], and 2-2'-bipyrimidine(bipym) [VO(bipym) and VO-(bipym)2], linked via nitrogen atoms, and 5'-bromo-2'-hydroxyacetophenone (acph) [VO(acph)2], linked via oxygen donor atom. The mono-chelated [VO(Me2-phen), compound 3] and bis-chelated-phen[VO(Me2-phen)2, compound 4] complexes were the most potent oxovanadium compounds and killed target cancer cells at low micromolar concentrations. Notably, the dimethyl substitution of the phenanthroline rings was essential for the anticancer activity of both compound 4 [VO(Me2-phen)2] and compound 3 [VO(Me2-phen)] because unsubstituted bis-chelated and mono-chelated phen oxovanadium(IV) complexes [VO(phen), compound 1, or VO(phen)2, compound 2] were less active. Addition of a chloro or nitro group to the phen complexes did not significantly improve the cytotoxic activity of the unsubstituted oxovanadium(IV) complexes. Irrespective of the ligands, bis-chelated phenanthroline containing compounds showed better activity than the mono-chelated phenanthroline containing complexes. The marked differences in the cytotoxic activity of oxovanadium(IV) complexes containing different heterocyclic ancillary ligands suggest that the cytotoxic activity of these compounds is determined by the identity of the five-member bidentate ligands, as well as the nature of the substitutents on the heterocyclic aromatic rings. Our results presented herein provide experimental evidence that oxovanadium compounds induce apoptosis in human cancer cells. Oxovanadium compounds, especially the lead compound VO(Me2-phen)2, may be useful in the treatment of cancer.     

Apoptosis Inducing Novel Anti-Leukemic Agent, Bis(4,7-Dimethyl-1,10 Phenanthroline) Sulfatooxovanadium(IV)[VO(SO4)(Me2-Phen)2] Depolarizes Mitochondrial Membranes

Bis(4,7-dimethyl-1,10 phenanthroline) sulfatooxovanadium(IV) [VO(SO₄)(Me₂-Phen)₂] induces apoptosis in human NALM-6 leukemia cells. In the present report, we demonstrate that VO(SO₄)(Me₂-Phen)2-induced apoptosis is mediated through the generation of reactive oxygen species (ROS), depletion of glutathione and depolarization of mitochondrial membrane potential (Δ±m). Using multilaser flow cytometry methods, we further mapped out the death sequence that occurs in VO(SO₄)(Me₂-Phen)2-treated leukemic cells. Triple labeling method to measure ROS, Δ±m and glutathione coupled with multilaser excitation flow cytometry showed that induction of ROS took place before the loss of mitochondrial permeability transition and depletion of glutathione. Correlated two parameter plots of glutathione content versus Δ±m showed that loss of Δ±m and depletion of glutathione closely follows each other. Translocation of phosphatidylserine to the outer leaflet of the cell membrane was the final step in the process before the cells became apoptotic. These results demonstrate that the mitochondrial permeability transition takes place during VO(SO₄)(Me₂-Phen)₂-induced apoptosis and is mediated through induction of ROS and depletion of glutathione.     

Bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(I.V.) as a novel antileukemic agent with matrix metalloproteinase inhibitory activity.

We have examined the in vitro anticancer activity of METVAN [bis(4,7-dimethyl-1,10 phenanthroline) sulfatooxovanadium(IV); VO(SO(4))(Me(2)-Phen)(2)] against acute lymphoblastic leukemia (ALL; NALM-6 and MOLT-3), acute myeloid leukemia (AML; HL-60), Hodgkin's disease (HS445), and multiple myeloma (ARH-77, U266BL, and HS-SULTAN) cell lines as well as primary leukemic cells from patients with ALL, AML, and chronic acute myeloid leukemia (CML). METVAN induced apoptosis in NALM-6, MOLT-3, and HL-60 cells in a concentration-dependent fashion with EC(50) values of 0.19 +/- 0.03 microM, 0.19 +/- 0.01 microM, and 1.1 +/- 0.2 microM, respectively. METVAN induced apoptosis at low micromolar concentrations in primary leukemic cells from patients with ALL, AML, and CML. METVAN inhibited the constitutive expression of matrix metalloproteinase (MMP)-9 protein and its gelatinolytic activity in HL-60 cells and MMP-2 as well as MMP-9 gelatinolytic activities in leukemic cells from ALL, AML, and CML patients. Furthermore, METVAN inhibited the leukemic cell adhesion to the extracellular matrix proteins laminin, type IV collagen, vitronectin, and fibronectin and the invasion through Matrigel matrix. Further preclinical development of METVAN may provide the basis for the development of more effective chemotherapy programs.     

In vivo antitumor activity and in vitro cytotoxic properties of bis[1,2-bis(diphenylphosphino)ethane]gold(I) chloride

We have previously reported the cytotoxicity and antitumor activity of bis(diphenylphosphino)ethane (DPPE) and a variety of its transition metal complexes. During studies of the chemistry of a gold complex of this group [(AuCl)2(DPPE)], it was observed that this complex readily underwent ring closure on reaction with DPPE to form the tetrahedral complex [Au(DPPE)2]+. Various counterion forms (e.g., Cl-) of this cation were isolated and were found to exhibit a remarkably high stability in solution. Evaluation of [Au(DPPE)2]Cl in mice bearing i.p. P388 leukemia demonstrated that the compound produced an average of 87% increase in life span at its maximally tolerated dose (2-3 mumol/kg/day for 5 days). Activity was also seen in i.p. M5076 reticulum cell sarcoma (60% increase in life span) and s.c. mammary adenocarcinoma 16/c. Modest activity was evident in i.p. B16 melanoma and L1210 leukemia. A subline of P388 leukemia resistant to cisplatin was not cross-resistant to [Au(DPPE)2]Cl. In addition, combination therapy of [Au(DPPE)2]Cl and cisplatin against i.p. P388 demonstrated an advantage over single-agent therapy. In vitro studies of [Au(DPPE)2]Cl showed that the compound: is cytotoxic to tumor cell lines; is only minimally inhibited in its cytotoxic activity by the presence of serum; produces DNA protein cross-links and DNA strand breaks in cells; and inhibits macromolecular synthesis with a preferential inhibitory effect on protein synthesis relative to DNA and RNA synthesis. 31P nuclear magnetic resonance spectroscopy indicated that the compound is stable in the presence of serum proteins, thiols, or disulfides and that it reacts with Cu(II) resulting in the formation of a Cu(I)DPPE complex. The results of these in vivo and in vitro experiments suggest that the contrasting pharmacological profile of [Au(DPPE)2]Cl with respect to other gold(I) phosphine complexes may be related to both the kinetic stability of the complex and its stability in the presence of thiols.     

In vitro and in vivo antitumor effects of (4-methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone

Purpose

(4-Methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone (PHT) is a phenstatin analog compound. PHT is a known tubulin inhibitor that has potent cytotoxic activity. In the present study, PHT was synthesized and its antitumor activity was determined using in vitro and in vivo experimental models.

Methods

The in vitro cytotoxic activity of the PHT was determined by the MTT assay. The antimitotic and hemolytic effects were determined based on the inhibition of sea urchin embryo development and lysis of mouse erythrocytes, respectively. In vivo antitumor activity was assessed in mice inoculated with sarcoma 180 cells.

Results

In vitro, PHT displayed cytotoxicity in tumor cell lines, showing IC₅₀ values in the nanomolar range. In addition, it inhibited sea urchin embryo development during all phases examined, first and third cleavage and blastula stage. However, PHT did not induce hemolysis using mouse erythrocytes, suggesting that the cytotoxicity of PHT does not involve membrane damage. The in vivo study demonstrated tumor inhibition rates of 30.9 and 48.2% for PHT at doses of 20 and 40?mg/kg, respectively. In addition, PHT was also able to increase the response elicited by 5-fluorouracil (5-FU) from 33.3 to 55.7%. The histopathological analysis of liver, kidney, and spleen showed that they were just moderately affected by PHT treatment. Neither enzymatic activity of transaminases nor urea levels were significantly affected. Hematological analysis showed leukopenia after 5-FU treatment, but this effect was prevented when 5-FU was combined with PHT.

Conclusions

In conclusion, PHT exhibited in vitro and in vivo antitumor effects without substantial toxicity.     

In vivo antitumor activity of tetrahydrobenz(a)anthraquinone derivatives

Female rats bearing DMBA induced mammary carcinomas were treated with a new anthraquinone derivative related to mitoxantrone. The drug was administered at a dose of 5 mg/kg daily for 10 days. Tumor regression was noted in 78% of the animals with growth rate reduced from +74.91% to -12.60%. The results demonstrate that replacement of a polar hydroxy group of mitoxantrone with a nonpolar hydrocarbon moiety does not impair its antitumor activity and in fact may influence its availability to endocrine systems.     

In vivo antitumor activity of the bitter melon (Momordica charantia)

The in vivo antitumor activity of a crude extract from the bitter melon (Momordica charantia) was determined. The extract inhibited tumor formation in CBA/H mice which had been given i.p. injections of 1.0 X 10(5) CBA/Dl tumor cells (77% of the untreated mice with tumors versus 33% of the treated mice with tumors after 6 weeks). The extract also inhibited tumor formation in DBA/2 mice which had been given i.p. injections of either 1 X 10(5) P388 tumor cells (0% of untreated mice survived after 30 days versus 40% survival of the treated mice) or 1 X 10(5) L1210 tumor cells (0% survival of untreated mice versus 100% of treated mice after 30 days). The in vivo antitumor effect required both the prior exposure of tumor cells to the extract (2 hr) in vitro and i.p., biweekly injections of the extract into the mice. The optimum dose for tumor inhibition (8 micrograms protein, biweekly, i.p.) was not toxic to mice for at least 45 days of treatment. This same treatment caused a marked enhancement of C3H mouse thymic cell response to concanavalin A in vitro. When compared to the untreated control mice, the bitter melon-injected animals exhibited a 4-fold-higher incorporation of tritiated thymidine into trichloroacetic acid-precipitable material after 48 hr of exposure to 50 micrograms of concanavalin A. Nylon wool-purified spleen cells from these same bitter melon-treated mice exhibited an enhanced mixed lymphocyte reaction when exposed to irradiated P388 stimulator cells (186% of the untreated control mice). These data indicate that in vivo enhancement of immune functions may contribute to the antitumor effects of the bitter melon extract.     

In vivo potentiation of cis-diamminedichloroplatinum (II) antitumor activity by pretreatment with sparsomycin

The influence of protein synthesis inhibition by sparsomycin (Sm) on in vivo cisplatin activity has been studied on BALBc X DBA2: F1 mice bearing L1210 leukemia i.p. Sm alone at the dose range from 0.5 to 3.0 mg/kg did not significantly improve animal survival. Sm potentiated cisplatin activity only when given 3 or 6 h prior to cisplatin (P less than 0.001). Sm 0.5-1.5 mg/kg 3 h prior to cisplatin resulted in a significant prolongation of animal survival (P less than 0.001) and 66% cures in each group versus 0% due to cisplatin alone. Sm pretreatment decreased weight loss due to cisplatin suggesting that it probably is able to decrease cisplatin toxicity.     

In vivo antitumor activity of tumor-infiltrating lymphocytes expanded in recombinant interleukin-2

A method was described for the generation of cells from tumor-bearing mice; these cells were capable of exhibiting significant antitumor reactivity when adoptively transferred into tumor-bearing hosts. Tumor cell suspensions from a variety of tumors were able to be separated using enzymatic techniques and they were cultured in medium containing recombinant interleukin-2. Activated infiltrating lymphocytes within these tumors expanded; and, by 6-8 days after initiation of culture, lymphocytes predominated and were able to grow to large numbers. The adoptive transfer of these tumor-infiltrating lymphocytes (TILs) made possible mediation of the reduction of established 3-day pulmonary micrometastases from 5 of 7 tumors tested, including two 3-methylcholanthrene (CAS: 56-49-5)-induced sarcomas, one 1,2-dimethylhydrazine (CAS: 540-73-8)-induced colon carcinoma, and the B16 melanoma, all in C57BL/6 mice, as well as the 1660 bladder carcinoma in BALB/c mice. Approximately 2-4 X 10(6) transferred cells were capable of totally eliminating 3-day established metastases. These cells were thus 50 to 100 times more effective than lymphokine-activated killer cells in reducing established metastases; however, they could not be generated from all tumors. The concomitant administration of recombinant interleukin-2 enhanced, by approximately fivefold, the in vivo activity of these cells. The specificity of action of TILs in vivo was different from that determined by classic amputation rechallenge experiments. The tumor-infiltrating lymphocytes that developed this antitumor reactivity appeared to be Thy-1+ and did not bear the asialo GM1 antigen. The potent antitumor effect of these TILs, when transferred in vivo to tumor-bearing hosts, raises the possibility of utilizing similar approaches for the isolation and therapeutic use of lymphocytes with antitumor reactivity from human tumors.     

In vitro cancer chemotherapeutic activity of 1,10-phenanthroline (phen), [Ag2(phen)3(mal)]x2H2O, [Cu(phen)2(mal)]x2H2O and [Mn(phen)2(mal)]x2H2O (malH2=malonic acid) using human cancer cells

The chemotherapeutic potential of 1,10-phenanthroline (phen), and three of its transition metal complexes, namely [Cu(phen)(2)(mal)]x2H(2)O, [Mn(phen)(2)(mal)]x2H(2)O and [Ag(2)(phen)(3)(mal)]x2H(2)O (malH(2)=malonic acid) was determined using two human carcinoma cell lines (A-498 and Hep-G2). Phen and the three metal-phen complexes induced a concentration-dependent cytotoxic effect, with metal complexes demonstrating the greatest cytotoxic response. In comparative studies, IC(50) values show cytotoxicity of between 3 and 18 times greater than that observed for the metal-based anti-cancer agent, cisplatin. All of the phen-based complexes inhibited DNA synthesis which did not appear to be mediated through intercalation. Also, the potential cancer chemotherapeutic application of these compounds was seen to be enhanced by results obtained from Ames tests, which showed all of the test agents and their phase I metabolites were non-mutagenic. Taken together, these results suggest that phen and the three metal-phen complexes may have a therapeutic role to play in the successful treatment and management of cancer.     

Preclinical antitumor activity of orally administered platinum (IV) complexes

Several novel platinum (IV) mixed ammine/amine dicarboxylate dichlorides of general structure [Pt(IV)Cl₂ (OCOY)₂ NH₃(XNH₂)], where Y is aliphatic or aromatic and X is alicyclic or aliphatic, known to be particularly well absorbed following oral administration, were evaluated by that route for their antitumor activity. Testing of the Pt(IV) derivatives took place concomitantly with i.v. administered cisplatin and carboplatin in two s.c. staged tumor models, the murine M5076 sarcoma and human A2780 ovarian carcinoma. Based upon repetitive experiments which included an evaluation of different vehicles and treatment schedules, each of the orally administered Pt(IV) dicarboxylates was reproducibly active in the M5076 tumor, producing mean maximum gross log cell kill (LCK) values of between 1.5 and 2.0, and lifespan increases, reflected by mean maximum treated/control median survival (T/C) values, of 139–151%. Cisplatin and carboplatin given i.v. yielded mean maximum LCK of 3.5 and 2.5, respectively, as well as mean maximum T/C values of 166% and 164%, respectively, in the same tumor model. The best of the derivatives in the M5076 experiments, JM-216 [ammine/cyclohexylamine diacetato dichloride Pt(IV), produced LCK values that averaged only 0.5 lower than that of carboplatin, and increases in lifespan not significantly different than that of carboplatin. Against the A2780 tumor, the Pt(IV) dicarboxylates produced individual best effects of between 0.8–1.1 LCK, based on data from two or three experiments. The mean maximum LCK values for cisplatin and carboplatin were 1.8 and 2.2 LCK, respectively. JM-225, ammine/cyclopentylamine diacetato dichloride Pt(IV), was active in two of three experiments, including one result comparable to that of carboplatin. The Pt(IV) mixed ammine/amine dicarboxylate dichlorides represent a novel class of Pt derivative capable of expressing oral antitumor activity in both murine and human tumor models.     

In vivo antitumor activity of cis-bis-neodecanoato-trans- R,R-l,2-diaminocyclohexane platinum(II) formulated in long-circulating liposomes

 A lipophilic cisplatin derivative, cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum(II) (NDDP), was formulated in liposomes composed of phosphatidylcholine (PC) and cholesterol (Chol) additionally containing monosialoganglioside (G_M1) or polyethyleneglycol conjugated to phosphatidylethanolamine (PEG-PE). These NDDP-containing long-circulating liposomes were examined for in vivo antitumor activity using the mouse RIF-1 solid tumor as a target residing outside the reticuloendothelial system (RES). Biodistribution studies, using C3H/HeJ mice and ¹¹¹In-labelled DTPA-SA as a lipid marker, showed that the activity of G_M1 and PEG-PE in prolonging the circulation times of liposomes was preserved in the presence of 3.0 mol% of NDDP in the liposome membranes. The high levels of liposomes remaining in the blood for PC/Chol/G_M1 and PC/Chol/PEG3000-PE liposomes were associated with high levels of platinum in the blood as determined by atomic absorption spectrophotometry. These NDDP-containing long-circulating liposomes showed approximately a three-fold increase in tumor accumulation as compared to the conventional PC/Chol liposomes. In vitro cytotoxicity studies using RIF-1 tumor cells showed that the presence of PEG-PE, but not G_M1, significantly enhanced the cytotoxicity of liposomal NDDP. RIF-1 tumor-bearing C3H/HeJ mice were treated twice with 25 mg/kg NDDP in various liposomal formulations on days 12 and 16 after tumor cell inoculation. A significant reduction in the tumor growth rate was observed when NDDP was formulated in PC/Chol/PEG3000-PE liposomes which support both efficient tumor accumulation and enhanced cytotoxicity of liposomal NDDP. On the other hand, NDDP formulated in PC/Chol/G_M1 liposomes, which display only a high tumor accumulation, had no effect on the tumor growth rate. Furthermore, NDDP formulated in dimyristoylphosphatidylglycerol (DMPG) containing liposomes, exhibiting in vitro cytotoxicity comparable to NDDP formulated in PC/Chol/PEG3000PE liposomes, but showing poor tumor accumulation, was also not effective. These results indicate a potential effectiveness of NDDP formulated in PEG-PE-containing liposomes for therapy of tumors in non-RES organs. Received: 13 November 1994/Accepted: 14 May 1995     

In vitro antitumour activity and cellular pharmacological properties of the platinum-iminoether complex trans-[PtCl2[E-HN=C(OMe)Me]2].

The platinum complex trans-[PtCl2?E-HN=C(OMe)Me?2] was compared to cisplatin for cytotoxicity towards tumour cells, and for cellular pharmacological properties in A2780 and cisplatin-resistant A2780/Cp8 ovarian cancer cells. Trans-[PtCl2?E-HN=C(OMe)Me?2] was comparably cytotoxic to cisplatin (mean IC50 after 72 h exposure = 6. 1 microM and 7 microM, respectively) and did not show cross-resistance in A2780/Cp8 cells (resistance factor = 0.9). Cellular accumulation measurements after treatment with equimolar drug concentrations showed that trans-[PtCl2?E-HN=C(OMe)Me?2] entered both A2780 and A2780/Cp8 cells much more efficiently than cisplatin, whose accumulation was reduced in A2780/Cp8 cells. Unlike cisplatin, trans-[PtCl2?E-HN=C(OMe)Me?2] induced rapidly cell death and cell cycle modifications of treated cells, thus indicating substantially different mechanistic properties.     

In vivo antitumor activity of S 16020-2, a new olivacine derivative

 The antitumor activity of S 16020-2, a new olivacine derivative, was investigated in vivo and compared with that of Adriamycin and elliptinium acetate in a panel of murine (P388 leukemia, M5076 sarcoma, Lewis lung carcinoma, and B16 melanoma) and human (NCI-H460 non-small-cell lung and MCF7 breast carcinomas) tumor models. S 16020-2 given i.v. was active against P388 leukemia implanted i.p., s.c., or intracerebrally. The therapeutic effect of an intermittent schedule (administration on days 1, 5, 9) was superior to that of single-dose treatment, allowing the i.v. administration of high total doses of S 16020-2 and resulting in the cure of 60% of mice in the i.p. P388 model. In this model, S 16020-2 was more active than elliptinium acetate and showed a better therapeutic index than Adriamycin:≥8 versus 2. A good therapeutic effect of S 16020-2 was also observed in three P388 leukemia sublines displaying the classic multidrug-resistance phenotype, namely, P388/VCR, P388/VCR-20, and P388/MDRC.04, the latter being totally insensitive to vincristine and Adriamycin. However, S 16020-2 was not active against the P388/ADR leukemia, a model highly resistant to adriamycin in vivo. S 16020-2 was both more active than Adriamycin and curative in the M5076 sarcoma and Lewis lung carcinoma implanted s.c. In the B16 melanoma implanted i.p. or s.c., S 160202 was less active than Adriamycin. Against the NCI-H460 human tumor xenograft, S 16020-2 demonstrated activity superior to that of Adriamycin (T/C=20% versus 43% on day 21). Against the MCF7 breast cancer xenograft, S 16020-2 was active, but less so than Adriamycin (T/C=23% versus 9% on day 21), whereas elliptinium acetate was marginally active (T/C=49% on day 24). The hematological toxicity of S 16020-2 given to B6D2F1 mice at pharmacological dose appeared to be less severe than that of Adriamycin, particularly in bone-marrow stem cells. These results demonstrate that S 16020-2 is a highly active antitumor drug in various experimental tumor models and is markedly more efficient than elliptinium acetate. Because of its pharmacological profile, which is globally different from that of Adriamycin, S 16020-2 is considered an interesting candidate for clinical trials. Received: 21 October 1995/Accepted: 4 March 1996     

Antitumor activity of homo-aza-steroidal esters of [p-[bis(2-chloroethyl)amino]phenyl]acetic acid and [p-[bis(2-chloroethyl)amino]phenyl]butyric acid

Summary Three new modified steroidal alkylating agents, 3-hydroxy-13-amino-13,17-seco-5-androstan-17-oic-13,17-lactam-p-bis(2-chloroethyl)aminophenylacetate, 3-hydroxy-13-amino-13,17-seco-5-androstan-17-oic-13,17-lactam-p-bis-(2-chloroethyl)aminophenylbutyrate, and 17-hydroxy-3-aza-A-homo-4-androsten-4-one-p-N,N-bis(2-chloroethyl)-aminophenylacetate are active in treatment of L1210 and P388 leukemias. A stereoisomer of the first compound, 3-hydroxy-13-amino-13,17-seco-5-androstan-17-oic-13, 17-lactam-p-bis(2-chloroethyl)aminophenylacetate, was tested in L1210 leukemia. This stereoisomer, in which the alkylating agent is linked to the modified steroid in the axial position, is active only at much higher doses in L1210 leukemia. The results of testing these compounds and previous results from similar compounds allow certain conclusions to be drawn regarding structure-activity relationships. The presence of the lactam moiety is the major structural feature that confers activity in the murine leukemias. The steric arrangement of the alkylating moiety at position 3 and the hydrogen atom at position 5 influence toxicity and antileukemic activity.     

Sequence-dependent antitumor activity of paclitaxel (taxol) and cisplatin in vivo

The established antitumor efficacy of paclitaxel and cisplatin as single agents and their distinctly different mechanisms of action have prompted laboratory and clinical research into their use in combination. Our in vivo study was performed to investigate the importance of sequence of administration and inter-agent interval. C3Hf/Kam mice bearing OCa-1 tumors received paclitaxel and cisplatin. The antitumor efficacy of the combination, measured as re-growth delay and expressed as the enhancement factor (EF), was determined for inter-agent intervals of I, 9, 24, 48 and 72 hr. Morphometric analysis was used to determine the contribution of induced apoptosis. Our findings showed an additive effect when cisplatin preceded paclitaxel by 1 and 24 hr, producing EF of 1.1 and 1.0, respectively, and a greater than additive effect for 9 and 48 hr, producing EF of 1.3 and 1.8, respectively. This sequence, however, was associated with significant morbidity and mortality. When paclitaxel preceded cisplatin the effect was greater than additive with the EF for I, 9 and 24 hr, being 1.2, 1.5 and 1.5, respectively, and increasing to a maximum of 1.9 at 48 hr. Thus, for this combination, the therapeutic ratio was improved when paclitaxel preceded cisplatin and was greatest when a 48 hr interval was allowed between drugs. We were unable to attribute the efficacy of the drug combination to increased induction of apoptosis and suggest other possible mechanisms. © 1995 Wiley-Liss, Inc.     

In vivo antitumor activity of 9-[(2-phosphonylmethoxy)ethyl]-guanine and related phosphonate nucleotide analogues

Phosphonylmethoxyalkylpurine analogues were evaluated for their antitumor activity in murine tumor models. Three compounds, (S)-9-[(3-hydroxy-2-phosphonylmethoxy)propyl]adenine (HPMPA), 9-[(2-phosphonylmethoxy)ethyl]adenine (PMEA), and 9-[(2-phosphonylmethoxy)ethyl]guanine (PMEG) were modestly active with treated versus control (T/C) values of 125%-175% versus intraperitoneal P388 leukemia, but were inactive versus intravenously implanted P388. The most active and most potent of the three was PMEG, which was also evaluated against subcutaneously (SC) implanted B16 melanoma. In confirmatory experiments, optimal therapy with PMEG yielded reproducible increases in life span (T/C values of 164%-170%) and delays in primary tumor growth (7.3- to 13.0-day T-C values). PMEG is representative of a new class of antitumor antimetabolites heretofore recognized only for their antiviral properties.