Lonidamine as a modulator of alkylating agent activity in vitro and in vivo

We are searching for relatively nontoxic compounds that can positively modulate the efficacy of antitumor alkylating agents. Lonidamine inhibits cellular energy metabolism and could potentially increase damage by alkylating agents if cellular defenses are energy requiring. Exposure of cells to lonidamine (500 microM) for 2 h under hypoxic conditions followed by 1-h exposures to lonidamine plus alkylating agents under normally oxygenated conditions in vitro significantly increased the cell kill achieved by cis-diamminedichloroplatinum(II) (CDDP) approximately 5-fold and by D-tetraplatin approximately 10-fold at 90% inhibitory concentration in MCF-7/CDDP (CDDP-resistant) cells. Carboplatin cytotoxicity, however, was little changed. In the MCF-7 parent cell line, treatment with lonidamine increased CDDP cytotoxicity by approximately 10-fold, D-tetraplatin by approximately 10-fold, and carboplatin by approximately 8-fold at the 90% inhibitory concentration. For L-phenylalanine mustard (melphalan), N,N',N"-triethylenethiophosphoramide (thiotepa), and N,N'-bis(2-chloroethyl)-N-nitrosourea, little resistance was evident in the MCF-7/CDDP lines compared with the parent line. Treatment with lonidamine increased the cytotoxicity of each drug by 1.5- to 3-fold in both cell lines. When exposure to lonidamine was extended to 24 h before and 12 h after drug exposure in MCF-7 normally oxygenated cultures, CDDP (250 microM) cytotoxicity was increased by approximately 100-fold, but melphalan cytotoxicity was increased only 2- to 3-fold over the concentration range tested. In the FSaIIC murine fibrosarcoma tumor system, five i.p. injections of 50 mg/kg of lonidamine over 36 h increased the tumor cell kill by CDDP and carboplatin approximately 2- to 3-fold over the dose range tested when the platinum complexes were given i.p. immediately after the third lonidamine injection. When cyclophosphamide and thiotepa were given in the same schedule, 10-fold increases in tumor cell killing were evident on tumor excision assay over the dosage ranges. The increase in bone marrow toxicity caused by lonidamine in addition to the alkylating agents was less than for tumor cells. Finally, in the EMT6 murine mammary carcinoma, use of lonidamine at 500 mg/kg twice daily along with CDDP, carboplatin, thiotepa, and cyclophosphamide significantly increased tumor growth delays by approximately 1.6- to 3.0-fold. The results suggest that lonidamine can positively modulate antitumor alkylating agent cytotoxicity and may be a clinically useful adjunctive therapy with these drugs.     

Etoposide with lonidamine or pentoxifylline as modulators of alkylating agent activity in vivo

In an effort to improve the additive anti-tumor efficacy of commonly used alkylating agents, the topoisomerase-II inhibitor etoposide was used in combination with either the mitochondrial poison and energy-depleting agent lonidamine or the hemorheologic agent and tumor-blood-flow-increasing agent pentoxifylline. In the FSaIIC murine fibrosarcoma system, these modulators were evaluated for modulation of whole-tumor cell killing vs. bone-marrow CFU-GM toxicity with the alkylating drugs CDDP, CTX, L-PAM or BCNU. Etoposide alone was essentially additive with the alkylating drugs for both tumor-cell and bone-marrow killing, except for BCNU, where a substantial increase in tumor-cell killing occurred (0.5 to 2.0 logs over the dose range of BCNU tested) without a significant increase in bone-marrow toxicity. Etoposide plus lonidamine was significantly more active than etoposide alone only with CTX and BCNU in tumor-cell vs. bone-marrow killing. Etoposide plus pentoxifylline was also most active with these two alkylating agents, where increases in tumor-cell killing of 0.5 to 1.0 log were observed. Hoechst-33342-defined tumor-cell sub-population studies revealed that etoposide significantly improved the killing of dim (putative hypoxic) cells by CDDP, but neither lonidamine nor pentoxifylline significantly improved killing of bright or dim cells together. With CTX, etoposide plus lonidamine or pentoxifylline substantially improved killing of dim cells over etoposide alone (each by about 0.8 logs). These data indicate that a therapeutic advantage may be achievable by combining etoposide with lonidamine or pentoxifylline for use with alkylating drugs.     

Modulation of [cis-diaminedichloroplatinum(ii) hyperthermia] therapy by inhibitors of arachidonic-Acid metabolism

Previous studies have shown that hyperthermia is an effective modulator of cis-diamminedichloroplatinum(II) (CDDP) cytotoxicity. We have examined the potential of inhibitors of the arachidonic acid metabolism to increase the antitumor activity of CDDP and hyperthermia. Sulindac and diflunisal are cyclooxygenase inhibiting non-steroidal anti-inflammatory drugs (NSAIDS) and phenidone is a lipoxygenase inhibitor. Using the FSaIIC in vivo-in vitro excision assay, neither five daily injections of sulindac nor diflunisal added to the killing of FSaIIC cells achieved by one injection of CDDP at normal temperature. When the i.p. injection of CDDP and the NSAIDS were followed immediately by hyperthermia treatment to the tumor bearing limb at 43-degrees-C for 30 min, the cell killing achieved was increased by 2-3-fold by diflunisal over the dose range of CDDP examined but was unaffected by sulindac. Phenidone did not alter the cell killing achieved by CDDP at normal temperature or when the CDDP was followed by local hyperthermia, but use of a combination of sulindac or diflunisal plus phenidone increased the cell killing achieved by 2-10-fold when used with local hyperthermia over the dose range of CDDP tested. In tumor growth delay (TGD) studies, addition of five daily injections of sulindac, diflunisal or phenidone did not increase the TGD achieved by CDDP at normal temperature and neither diflunisal nor phenidone markedly increased the TGD produced by CDDP in conjunction with local hyperthermia, but the administration of sulindac resulted in about a 3-fold increase in TGD as did use of a combination of diflunisal or sulindac plus phenidone. These results indicate that inhibitors of arachidonic acid metabolism can increase the cell killing and the tumor growth delay produced by CDDP plus local hyperthermia.     

Cyclooxygenase inhibitors - invitro and invivo effects on antitumor alkylating-agents in the emt-6 murine mammary-carcinoma

The nonsteroidal antiinflammatory drugs that inhibit cyclooxygenase block the formation of prostanoids in vivo. These agents may be useful as modulators of cytotoxic anticancer therapies. EMT-6 mouse mammary carcinoma cells growing in culture were exposed for 1 h or 24 h to eleven different nonsteroidal antiinflammatory agents or acetaminophen. None of these drugs was very cytotoxic. A concentration of 50muM of the nonsteroidal antiinflammatory drugs or acetaminophen was chosen for modulator combination studies with the antitumor alkylating agents CDDP, L-PAM, BCNU and 4-HC in cell culture. Several of the modulators protected the EMT-6 cells from the cytotoxicity of the antitumor alkylating agents; however, diflunisal, sulindac, indomethacin, acetaminophen and in some cases ibuprofen and tolmetin were positive modulators of the antitumor alkylating agents under the cell culture conditions tested. EMT-6 tumor cell survival studies and bone marrow CFU-GM survival studies were carried out with seven of the modulators and various doses of cyclophosphamide. Tolmetin, ibuprofen, sulindac, piroxicam and diflunisal in combination with cyclophosphamide produced increased tumor cell killing compared with cyclophosphamide alone without marked changes in toxicity to the bone marrow derived CFU-GM. In EMT-6 tumor growth delay experiments, none of the six modulators tested affected the growth of the tumors; however, tolmetin, ibuprofen, diflunisal and sulindac increased the tumor growth delay obtained with standard dose-schedules of cyclophosphamide or CDDP. When minocycline, a collagenase inhibitor, was added to treatment regimens including diflunisal or sulindac and either cyclophosphamide, CDDP or L-PAM further increases in tumor growth delay were obtained especially when L-PAM was the cytotoxic therapeutic agent. The number of lung metastases and the percentage lung metastases with diameters >3 mm were reduced by treatment with the modulator combinations alone and further reduced with the addition of the antitumor alkylating agents. These results indicate that agents which inhibit signaling pathways among tumor cells and between tumor cells and normal cells can be useful additions to cytotoxic therapies.     

Advantages in combination chemotherapy using cisplatin and its analogues for human testicular tumor xenografts

The antitumor effects and toxicities of combination chemotherapies using cisplatin (CDDP) and its analogues were compared with those of single drug therapies. Congenitally athymic nude BALB/c (nu/nu) mice were used to estimate antitumor activities of these compounds against human testicular tumor (Ht-14) xenografts and hetero-BALB/c (nu/+) mice were used to evaluate the toxic effects of the drugs. Combination therapy with half dosages of CDDP and carboplatin (JM8) (CDDP: 2, JM8: 20 mg/kg/day for 5 days), or of CDDP and (glycolato-O,O')-diammineplatinum (II) (254S) (CDDP: 2,254S: 4 mg/kg/day for 5 days), resulted in significant tumor regression. The combination of CDDP and JM8 had the highest therapeutic efficacy while the CDDP and 254S combination had a lower antitumor potency. In addition, the toxicities of the combination therapies were lower than what was produced by the highest dosage of CDDP (4 mg/kg/day for 5 days). These results demonstrated that the antitumor activities of these combination chemotherapies were equal or superior to the activity of CDDP or an analogue alone, and that the toxicities produced by these combinations were more manageable than those produced by single drug therapies.     

Fluosol-DA/carbogen with lonidamine or pentoxifylline as modulators of alkylating agents in the FSaIIC fibrosarcoma

Summary In an effort to increase the efficacy of several antineoplastic alkylating agents (CDDP,l-PAM, CTX, or BCNU), we examined the effect of the modulator Fluosol-DA/carbogen in combination with a second modulator, either lonidamine or pentoxifylline, on the survival of FSaIIC tumor cells and of bone marrow CFU-GM from tumor-bearing C3H mice. Fluosol-DA/carbogen increased the tumor-cell killing activity of each alkylating agent by about 10 times. In contrast, lonidamine alone did not significantly increase the cytocidal activity of any of the alkylating agents tested. However, in combination with Fluosol-DA/carbogen, the use of lonidamine produced about a 100-fold increase in the tumor cell kill achieved with CDDP as compared with CDDP alone. No increase in tumor cell kill over that produced with the single modulator Fluosol-DA/carbogen was seen following the addition of lonidamine to the combination treatment withl-PAM, CTX, or BCNU. Unfortunately, although neither lonidamine nor Fluosol-DA/carbogen alone significantly increased alkylator toxicity to bone marrow CFU-GM, the combination of modulators increased the toxicity of each alkylating agent to bone marrow by about 10 times. Pentoxifylline caused an increase in alkylator activity against the FSaIIC fibrosarcoma only when used with BCNU; this effect was further augmented by the addition of Fluosol-DA/carbogen. The combination of modulators pentoxifylline plus Fluosol-DA/carbogen was more effective than Fluosol-DA/carbogen alone only when the former was used with BCNU, whereas only minimal increases in tumor-cell killing activity were obtained with this modulator combination and CDDP,l-PAM, or CTX. Pentoxifylline increased the bone marrow CFU-GM toxicity ofl-PAM by about 10 times. The bone marrow CFU-GM toxicity was further increased by Fluosol-DA/carbogen, as was the toxicity of each of the other alkylating agents. Lonidamine plus Fluosol-DA/carbogen may be useful in increasing the therapeutic efficacy of CDDP, and the combination of pentoxifylline plus Fluosol-DA/carbogen might improve the antitumor activity of BCNU.Abbreviations CDDP cis-diamminedichloroplatinum(II) - l-PAM l-phenylalanine mustard, melphalan - thioTEPA N,N,N-triethylenethio-phosphoramide - CTX cyclophosphamide - BCNU N,N-bis(2-chloroethyl)-N-nitrosourea - CFU-GM granulocyte-macrophage colony-forming unit - MEM alpha minimal essential medium - PBS phosphatebuffered saline This work was supported by National Cancer Institute grant IPO1-CA38493, by a grant from DeSanctis Consultants, Montreal, Canada, and by a grant from the Mathers Foundation     

Advantages in Combination Chemotherapy Using Cisplatin and Its Analogues for Human Testicular Tumor Xenografts

The antitumor effects and toxicities of combination chemotherapies using cisplatin (CDDP) and its analogues were compared with those of single drug therapies. Congenitally athymic nude BALB/c ( nu / nu ) mice were used to estimate antitumor activities of these compounds against human testicular tumor (Ht-14) xenografts and hetero-BALB/c ( nu /+) mice were used to evaluate the toxic effects of the drugs. Combination therapy with half dosages of CDDP and carboplatin (JM8) (CDDP: 2, JM8: 20 mg/kg/day for 5 days), or of CDDP and (glycolato-O, O')-diammineplatinum (II) (254S) (CDDP: 2, 254S: 4 mg/kg/day for 5 days), resulted in significant tumor regression. The combination of CDDP and JM8 had the highest therapeutic efficacy while the CDDP and 254S combination had a lower antitumor potency. In addition, the toxicities of the combination therapies were lower than what was produced by the highest dosage of CDDP (4 mg/kg/day for 5 days). These results demonstrated that the antitumor activities of these combination chemotherapies were equal or superior to the activity of CDDP or an analogue alone, and that the toxicities produced by these combinations were more manageable than those produced by single drug therapies.     

Chemosensitivity of adriamycin, mitomycin C, and bleomycin with in vitro colony assay

In vitro colony assay was used to examine the sensitivities of adriamycin (ADM), mitomycin C (MMC), and bleomycin (BLM), and the effects of a prior chemotherapy on in vitro chemosensitivities of the drugs. One hundred forty-seven tumor specimens from 106 patients with various malignancies were placed in culture. Seventy tumors (56.0%) from 125 evaluable specimens which had histologically or cytologically confirmed to be malignant, and were plated at 5 x 10(5) cells/plate formed more than 30 colonies/plate enough for sensitivity assays. The results of in vitro sensitivities of the drugs were nearly similar to those reported in the clinical trials. The in vitro antitumor activity of BLM was noted in 3 (21.4%) of 14 patients with ovarian cancer, therefore the results suggest that the assay is useful to select effective drugs against tumors in which phase II study has never been performed. In vitro sensitivity of BLM was markedly reduced by a prior chemotherapy containing the same drug (p less than 0.05), and prior therapeutic ADM exposure also reduced in vitro activity of the drug, whereas there was no significant influence on in vitro activity of MMC. These results indicate the usefulness of the in vitro colony assay for predicting clinical antitumor activities of ADM, MMC, and BLM.     

Study on the chemosensitivity of liver cell carcinoma by subrenal capsule assay

Chemosensitivity of liver cell carcinoma was studied by subrenal capsule assay. The method of assay was based on Bogden's one, but the antitumor activity was evaluated by tumor growth inhibition rate (TG-IR). The anticancer agent with more than 50% TG-IR was judged as positive in the chemosensitivity test. Of 3 human hepatoma cell lines transplanted in the subcutaneous space of nude mice, all of 3 were evaluable. The positive rates of ADR, MMC, CDDP, 5-FU and CPA were 66.7%, 100%, 66.7%, 100% and 0%, respectively. Of 24 patients who provided fresh tumor specimens for the assay, 12 (50%) were evaluable. The positive rates of ADR, MMC, CDDP, 5-FU and CPA were 25%, 16.7%, 16.7%, 33.3% and 8.3%, respectively. Our study suggested that 5-FU, MMC and ADR were comparatively active against the hepatoma cell, CDDP was less active than these 3 agents, CPA was inactive. These results seem to justify the use of current anticancer agents against hepatic cell carcinoma and indicate the usefulness of SRC assay for selecting chemotherapeutic agents against liver cell carcinoma.     

Efficacy of lonidamine combined with different DNA-damaging agents in the treatment of the MX-1 tumor xenograft

 Lonidamine is an antitumor agent with a peculiar mechanism of action, since it differentially impairs the energy metabolism of normal and neoplastic cells. We investigated the effects of lonidamine on the activity of DNA-damaging antitumor agents against the MX-1 human breast carcinoma xenograft. Athymic mice bearing measurable s.c. tumors were treated by a single injection of doxorubicin (i.v.), cyclophosphamide (i.v.), or cisplatin (i.p.) followed by repeated daily injections of lonidamine (i.p. or p.o.). A potentiation of the activity of all these DNA-damaging drugs was achieved when each was given in combination with lonidamine, but for doxorubicin and cyclophosphamide the increase in antitumor activity paralleled the increase in lethal toxicity. In contrast, a therapeutic advantage of the combination was achieved for cisplatin and lonidamine as compared with cisplatin alone. Indeed, 6 mg/kg of cisplatin plus lonidamine cured all tumors, whereas the maximum tolerated dose of cisplatin alone (12 mg/kg) cured only six of eight tumors. In addition, the study indicated that the duration of lonidamine administration after injection of the cytotoxic drug influenced the tumor response and that prolonged treatment resulted in greater efficacy. These results document the ability of lonidamine to modulate the pharmacological activity of DNA-damaging drugs, thus suggesting that lonidamine may be a clinically useful cisplatin modulator. Received: 26 July 1995/Accepted: 6 October 1995     

Combined effect of PT-050 (recombinant human TNF) and antitumor drugs on syngeneic murine tumors

The combined effect of PT-050 (recombinant human TNF) and various antitumor drugs was investigated using murine colon 26 adenocarcinoma, Meth A sarcoma and B16 melanoma transplanted into syngeneic mice. When colon 26- or Meth A- bearing mice were intravenously given PT-050 in combination with mitomycin C (MMC), doxorubicin (DXR), cis-platinum (CDDP), 5-fluorouracil (5-FU) or cyclophosphamide (CPA), a significant synergistic effect was observed, that is, both the inhibition rate of tumor growth and the cured ratio were increased significantly when compared with those given each drug alone. Similarly, an augmentation of the antitumor effect was also observed in B16-bearing mice by a combined treatment with PT-050 and these antitumor drugs. These results suggest that the combination chemotherapy of PT-050 with various antitumor drugs may be useful for cancer therapy.     

Cytotoxicity of cis-[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(myristato)]-platinum (II) suspended in Lipiodol in a newly established cisplatin-resistant rat hepatoma cell line.

The cytotoxic activity of cis-[((1R,2R)-1,2-cyclohexanediamine-N, N')bis(myristato)]platinum (II) (SM-11355) was evaluated in a cisplatin (CDDP)-resistant tumor cell line, and compared with that of CDDP. H4-II-E / CDDP with acquired resistance to CDDP was established by continuous exposure of a rat hepatic tumor line, H4-II-E, to increasing concentrations of CDDP over 12 months. Compared with the parental cell line, this cell line exhibited an 8.8-fold increase in resistance to CDDP and was not cross-resistant to 1,2-diaminocyclohexane platinum (II) dichloride (DPC). There were no differences in sensitivity to six non-platinum antitumor drugs between H4-II-E and H4-II-E / CDDP, which suggests that H4-II-E / CDDP is not multidrug-resistant. Intracellular platinum accumulation and the formation of a platinum-DNA adduct following CDDP exposure were significantly reduced in H4-II-E / CDDP compared to the parental cell line. The acquired CDDP resistance in H4-II-E / CDDP appeared to be predominantly due to reduced CDDP uptake. H4-II-E / CDDP was also resistant to CDDP suspended in Lipiodol (CDDP / Lipiodol), but was not cross-resistant to SM-11355 suspended in Lipiodol (SM-11355 / Lipiodol). Also, there were no differences in intracellular platinum accumulation or the formation of platinum-DNA adducts after SM-11355 / Lipiodol exposure between H4-II-E and H4-II-E / CDDP. These results suggest that acquired CDDP resistance in H4-II-E / CDDP does not influence the cytotoxic activity of SM-11355 / Lipiodol.     

Cytotoxicity of cis-[((1R,2R)-1,2-Cyclohexanediamine-N,N')bis(myristato)]-platinum (II) Suspended in Lipiodol in a Newly Established Cisplatinresistant Rat Hepatoma Cell Line

The cytotoxic activity of cis -[((1 R ,2 R )-1,2-cyclohexanediamine- N , N' )bis(myristato)]platinum (II) (SM-11355) was evaluated in a cisplatin (CDDP)-resistant tumor cell line, and compared with that of CDDP. H4-II-E/CDDP with acquired resistance to CDDP was established by continuous exposure of a rat hepatic tumor line, H4-II-E, to increasing concentrations of CDDP over 12 months. Compared with the parental cell line, this cell line exhibited an 8.8-fold increase in resistance to CDDP and was not cross-resistant to 1,2-diaminocyclohexane platinum (II) dichloride (DPC). There were no differences in sensitivity to six non-platinum antitumor drugs between H4-II-E and H4-II-E/CDDP, which suggests that H4-II-E/CDDP is not multidrug-resistant. Intracellular platinum accumulation and the formation of a platinum-DNA adduct following CDDP exposure were significantly reduced in H4-II-E/CDDP compared to the parental cell line. The acquired CDDP resistance in H4-II-E/CDDP appeared to be predominantly due to reduced CDDP uptake. H4-II-E/CDDP was also resistant to CDDP suspended in Lipiodol (CDDP/Lipiodol), but was not crossresistant to SM-11355 suspended in Lipiodol (SM-11355/Lipiodol). Also, there were no differences in intracellular platinum accumulation or the formation of platinum-DNA adducts after SM-11355/Lipiodol exposure between H4-II-E and H4-II-E/CDDP. These results suggest that acquired CDDP resistance in H4-II-E/CDDP does not influence the cytotoxic activity of SM-11355/Lipiodol.     

TNFalpha contributes to the antitumor activity of a bispecific, trifunctional antibody

Immunological cancer therapies focus on the activation of immune effector cells yielding a specific antitumor activity. Disseminated tumor cells are regarded as the origin of metastases and consequently their elimination is the central objective of adjuvant immune therapies. The use of bispecific antibodies is an approach that is regarded as promising in order to fight those disseminated tumor cells. Unfortunately, the efficiency of these antibodies is limited by the fact that they usually activate a single class of effector cell, thus not yielding optimal immune response. In addition, tumor cells may down-regulate the antibody's target molecule and escape recognition. We have recently described results with an intact bispecific molecule, BiUII, that represents a new class of intact antibodies. These antibodies, termed "triomab", provide an excellent antitumor activity in vitro, a fact that most probably is attributable to the simultaneous activation of different classes of immune effector cells. We have now investigated this antitumor activity in more detail and demonstrate here that at least a dual mechanism accounts for triomab-mediated killing of tumor cells: besides direct cell-mediated killing, triomab induces the production of TNFalpha in PBMCs at concentrations that induce apoptosis in target cells. This bystander effect may be of special interest for the clinical application of triomab in terms of killing of target antigen-negative tumor cells.     

老年胃癌原发灶与淋巴结转移灶体外化疗药敏性的差异及意义

目的比较老年胃癌原发灶与淋巴结转移灶体外化疗药敏性的差异并探讨其意义。方法对35例伴淋巴结转移的老年胃癌患者(≥60岁)和31例对照组胃癌患者(<60岁)的肿瘤原发灶、淋巴结转移灶进行MTT法原代细胞培养化疗药敏性实验,比较不同病灶肿瘤细胞对11种化疗药物敏感性的差异。结果老年组患者有6/11种化疗药物对原发灶、淋巴结转移灶的肿瘤细胞抑制率不同(均P<0.05),其中L-OHP、CDDP、MMC、THP对转移淋巴结肿瘤细胞抑制率明显低于原发灶(均P<0.05),PTX、EPI对原发灶肿瘤细胞抑制率明显低于淋巴结转移灶(均P<0.05)。与对照组比较,原发灶5-FU、PTX、EPI、MMC、MTX对老年患者肿瘤细胞抑制率低于对照组(均P<0.05);转移灶中5-FU、L-OHP、CDDP对老年患者肿瘤细胞抑制率较对照组降低(均P<0.05)。结论老年胃癌淋巴结转移灶对化疗药物敏感性与原发灶及对照组比较均存在异质性;老年肿瘤原发灶的化疗药敏性结果不能准确反映转移淋巴结的耐药性。     

Enhancement of the effect of 5-aminolevulinic acid-based photodynamic therapy by simultaneous hyperthermia

In the present study, we have investigated a combination of photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) and simultaneous hyperthermia (HT) on osteosarcoma (HOSM-1) cells, squamous cell carcinoma (KB) cells and fibroblasts (HF), including an assessment of the differences in the sensitivity of these cells to such treatment in vitro. The intracellular accumulation of protoporphyrin IX (PPIX) formed by metabolism of ALA in mitochondria and the influence of the treatment on the mitochondrial membrane potential were evaluated using flow cytometry. The antitumor effects of HT, PDT using ALA (ALA-PDT) and ALA-PDT combined with HT (PDT+HT) were determined by an MTT assay. Western blot analysis of the expression of heat shock protein 60 (Hsp60) and Hsp70 was performed to evaluate the mitochondrial stress caused by each treatment. The intracellular PPIX accumulation in HOSM-1 cells was about 2-fold higher than that in KB cells. An antitumor effect of ALA-PDT and PDT+HT was obtained in each cell line, and indicated a synergistic interaction of the combination therapy in tumor cells. A marked degree of depolarization of the mitochondrial membrane was observed in both tumor cell lines, and there was no marked difference in the degree of depolarization between the cell lines. Marked expression of Hsp60 was observed in HOSM-1 cells treated with PDT+ HT and ALA-PDT, but not in KB cells. Slightly increased expression of Hsp70 was observed for all treatments in both tumor cell lines. These results suggest that the antitumor effect of ALA-PDT therapy against malignant tumor cells is enhanced by simultaneous HT. Furthermore, the differences in sensitivity to these therapies between the two cell types may have occurred because PPIX was not effectively utilized in HOSM-1 cells, compared to its utilization in KB cells.     

Enhanced Antitumor Efficacy of a Combination of CPT-11, a New Derivative of Camptothecin, and Cisplatin against Human Lung Tumor Xenografts

The objective of this study was to evaluate the antitumor efficacy of combined use of 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carhonyloxycamptothecin (CPT-11) and cisplatin (CDDP). The antitumor activities of CPT-11, CDDP and their combination against 3 human lung tumor xenografts were estimated using congenitally athymic BALB/c ( nu/nu ) mice. The doses were 47 mg/kg for CPT-11 and 6 mg/kg for CDDP on days 1, 5 and 9. In combination therapy, half of the single dosage of each agent was used. The doses were administered intraperitoneally. The antitumor activity and toxicity were evaluated in terms of the tumor volume and body weight change of mice, respectively. The combination therapy resulted in a statistically significant tumor regression compared to the use of only CPT-11 or CDDP in two tumor xenografts out of three. The toxicity of the combination therapy was no higher than that of CPT-11 or CDDP alone. These results suggest that the antitumor activity of the combination of CPT-11 and CDDP is superior to that of CPT-11 or CDDP alone.     

Cytotoxicity of lonidamine alone and in combination with other drugs against murine RIF-1 and human HT1080 cells in vitro

Lonidamine is an agent that is reported to inhibit recovery from potentially lethal damage. By itself, it has only mild anticancer activity. We have examined the ability of lonidamine to enhance the cytotoxicity of several drugs against a mouse and a human fibrosarcoma cell line in vitro. By itself, lonidamine showed only a limited cytotoxic effect with drug exposure up to 100 micrograms/ml and 24-h duration. Lower concentrations and shorter term exposures were not toxic to either of these tumor cell lines. When tested against the mouse line, the cytotoxicity of 5-fluorouracil, methotrexate, and etoposide was enhanced by lonidamine if the latter drug was given either before or after the exposure of the cells to the cytotoxic agents. For cisplatinum, bleomycin, mitomycin C, doxorubicin, and Actinomycin D, cytotoxicity was also enhanced, but only if lonidamine followed the other agents. In contrast, potentiation of 1,3-bis(2-chloroethyl)-1-nitrosourea toxicity was maximum when lonidamine preceded the nitrosourea. The human cells were more resistant to lonidamine and to the combination treatments than were the mouse cells. Nevertheless, substantial enhancement was seen particularly for cisplatin and mitomycin C. We examined in more detail the enhancement of cisplatin. Maximum interaction was obtained when lonidamine was given immediately following (or in conjunction with) the platinum agent. Our results suggest that lonidamine enhances the effects of several other agents in a time- and concentration-dependent manner and indicate a potential usefulness for lonidamine in multidrug therapy.     

Antitumor activity of a new platinum compound (glycolate-o,o') diammineplatinum (II) (254-S), against non-small cell lung carcinoma grown in a human tumor clonogenic assay system

(Glycolate-o,o') diammineplatinum (II) (254-S) is one of the platinum derivatives showing high activity against rodent solid tumors and lack of renal toxicity. We have used a human tumor clonogenic assay (HTCA) as a disease-oriented drug screening model for new antitumor drugs, in order to test the antitumor activity of 254-S against non-small cell lung carcinoma (NSCLC) and to compare its activity with that of cisplatin (CDDP) and of carboplatin (CBDCA). The overall in vitro response rate (defined as less than 50% survival of tumor colony forming units) for 254-S was observed in 10/29 and 20/30 evaluable specimens isolated freshly from NSCLC patients with continuous exposure at 1 and 10 micrograms/ml, respectively, indicating a positive dose-response relationship. Dose dependent cytotoxicity was also confirmed in 4 human tumor cell lines derived from NSCLC patients. The antitumor activity of 254-S was 3.6-fold that of CBDCA, but two-fifths that of CDDP. A comparison of these in vitro results with the toxic properties of 254-S such as low nephrotoxicity suggests that 254-S is a promising new drug against NSCLC.