Antitumor mechanisms of systemically administered epidermal growth factor receptor antisense oligonucleotides in combination with docetaxel in squamous cell carcinoma of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) is one of the most common malignancies worldwide, with low 5-year survival rates. Current strategies that block epidermal growth factor receptor (EGFR) have limited effects when administered as single agents. Targeting EGFR via intratumoral administration of phosphorothioate-modified antisense oligonucleotides has antitumor efficacy in xenograft models of SCCHN. Because intratumoral delivery of therapeutic agents has limited clinical application, the present study was undertaken to examine the therapeutic mechanisms of systemically delivered phosphorothioate-modified EGFR antisense oligonucleotides alone, or in combination with docetaxel, in a SCCHN xenograft model. EGFR antisense oligonucleotides were administered at 5 mg/kg i.p. daily in athymic mice bearing 1483 human SCCHN xenografts alone or in combination with docetaxel at 2.5 mg/kg i.p. once a week for 4 weeks. Administration of EGFR antisense oligonucleotides in combination with docetaxel improved antitumor efficacy and resulted in lower expression levels of EGFR, fewer proliferating cells, and more apoptotic cells in the tumors compared with controls. Systemic administration of phosphorothioated EGFR antisense oligonucleotides for 30 days increased the retention of docetaxel in the tumor by approximately 4-fold compared with tumors treated with docetaxel alone or docetaxel and EGFR sense oligonucleotides (P < 0.05). Combination of EGFR antisense oligonucleotides with low doses of docetaxel has antitumor efficacy, and it may be an effective treatment strategy for SCCHN.     

Antitumor activity of doxorubicin in combination with docetaxel against human breast cancer xenografts

In this study we assessed the in vivo antitumor activity of combined docetaxel (DOCE) and doxorubicin (DXR) treatment using 2 human breast carcinoma cell xenografts (R-27 and MX-1) in the nude mouse model. The transplanted tumors were allowed to reach exponential growth, whereupon 10 or 40 mg DOCE per kg alone (i.p.), 8 mg DXR per kg alone (i.v.), or 10 mg/kg DOCE (i.p.) and 8 mg/kg of DXR (i.v.), in the sequence of DOCE followed by DXR, were administered. The in vivo antitumor activity of combined DOCE and DXR was synergistic against R-27 and additive against MX-1. P-glycoprotein (P-gp) was detected immunohistochemically, and was highly expressed in R-27, but not in MX-1. In conclusion, DOCE may increase the antitumor activity of DXR against P-gp-positive breast cancer xenografts, such that the DOCE and DXR combination may be a useful treatment in clinical breast cancer.     

Discovery and development of novel anticancer drug capecitabine

Capecitabine (N4-pentyloxycarbonyl-5'-deoxy-5-fluorocytidine) is a novel oral fluoropyrimidine carbamate, which was designed to be sequentially converted to 5-fluorouracil (5-FU) by three enzymes located in the liver and in tumors. N4-alkoxycarbonyl-5'-deoxy-5-fluorocytidine derivatives including capecitabine pass intact through the intestinal tract and are sequentially converted to 5-FU by a cascade of the three enzymes. The first step is the conversion to 5'-deoxy-5-fluorocytidine (5'-DFCR) by carboxylesterase located in the liver, then to 5'-deoxy-5-fluorouridine (5'-DFUR) by cytidine deaminase highly expressed in the liver and various solid tumors, and finally to 5-FU by thymidine phosphorylase (dThdPase) preferentially located in tumor tissues. Among large numbers of the derivatives, capecitabine was selected based on its susceptibility to hepatic carboxylesterase, oral bioavailability in monkeys and efficacy in a human cancer xenograft. Capecitabine given orally yielded substantially higher concentrations of 5-FU within tumors than in plasma or normal tissue (muscle). The tumor 5-FU levels were also much higher than those achieved by intraperitoneal administration of 5-FU at equi-toxic doses. This tumor selective delivery of 5-FU ensured greater efficacy and a more favourable safety profile than with other fluoropyrimidines. In 24 human cancer xenograft models studied, capecitabine was more effective at a wider dose range and had a broader spectrum of antitumor activity than 5-FU, UFT or its intermediate metabolite 5'-DFUR. The susceptibility of the xenografts to capecitabine correlated with tumor dThdPase levels. Moreover, the conversion of 5'-DFUR to 5-FU by dThdPase in tumor was insufficient in a xenograft model refractory to capecitabine. In addition, the efficacy of capecitabine was enhanced by dThdPase up-regulators, such as by taxanes and cyclophosphamide and by X-ray irradiation. The efficacy of capecitabine may, therefore, be optimized by selecting the most appropriate patient population based on dThdPase status and/or by combining it with dThdPase up-regulators. Capecitabine has additional characteristics not found with 5-FU, such as potent antimetastatic and anticachectic actions in mouse tumor models. With these profiles, capecitabine may have substantial potential in cancer treatment.     

YM155, a novel survivin suppressant, enhances taxane-induced apoptosis and tumor regression in a human Calu 6 lung cancer xenograft model

Survivin, an apoptotic inhibitor, is overexpressed in the majority of human tumor types and represents a novel target for anticancer therapy. Taxanes induce a mitotic cell-cycle block through the inhibition of microtubule depolymerization, with subsequent elevated expression/stabilization of survivin. We investigated the administration of survivin suppressant YM155 monobromide (YM155), in combination with docetaxel, in a human non-small-cell lung cancer (NSCLC) xenograft model. Animals received a 7-day continuous infusion of YM155, 2 mg/kg, and/or three bolus doses of docetaxel, 20 mg/kg, according to three dosing schedules: YM155 administered concomitantly with docetaxel, before docetaxel, and after docetaxel. YM155 administered either concomitantly with or before docetaxel showed significant antitumor activity (tumor regression ≥ 99%), with complete regression of the established human NSCLC-derived tumors in mice (eight of eight and seven of eight animals, respectively). Significantly fewer complete responses (three of eight animals) were achieved when YM155 was administered after docetaxel. No statistically significant decreases in body weight were observed in the combination versus docetaxel groups. YM155 administered concomitantly with docetaxel resulted in significant decreases in mitotic and proliferative indices, and in a significant increase in the apoptosis index. Elevated survivin expression was seen in tumors from mice treated with docetaxel alone; a significant reduction in survivin expression was seen in tumors from mice treated with YM155 alone or in combination with docetaxel, but not in the control group. These results indicate that in a human NSCLC xenograft model YM155 in combination with docetaxel diminished the accumulation of survivin by docetaxel and induced more intense apoptosis and enhanced antitumor activity, compared with single-agent YM155 or docetaxel.     

Response of human tumor xenografts in athymic nude mice to docetaxel (RP 56976, Taxotere®)

Summary Docetaxel (Taxotere^?, RP 56976, NSC 628503), a new taxoid, was evaluated for preclinical evidence of anticancer activity in athymic nude (NCr-nu) mice bearing established, subcutaneously (s.c.) implanted human tumor xenografts CX-1 or KM20L2 (colon carcinomas), LX-1 (lung carcinoma), MX-1 (mammary carcinoma), and SK-MEL-2 (melanoma). Other evaluations used OVCAR-3 (ovarian carcinoma) xenografts implanted intraperitoneally (i.p.). Docetaxel was administered intravenously (i.v.) every 4 days for 3 injections (q4d×3) except for one OVCAR-3 experiment in which the drug was given i.p. every 7 days for 3 injections. Tumor measurements, animal body weights, and mortality were determined. The highest dosage used (50 mg/kg/dose) was toxic in all experiments in which the 4-day treatment interval was used. The maximally tolerated dosage (MTD) ranged from 15 to 33 mg/kg/dose. Therapeutic responses among these xenografts ranged from clinically important long-term tumor-free survivors (MX-1, SK-MEL-2, and OVCAR-3) to tumor growth delays of various durations (CX-1, LX-1, and KM20L2). The response of SKMEL-2, a xenograft highly refractory to available drugs, was particularly noteworthy. These results are indicative of a broad spectrum of antitumor activity for docetaxel.     

Cryptophycin 52 and cryptophycin 55 in sequential and simultaneous combination treatment regimens in human tumor xenografts

The antitumor activity of cryptophycin 52 (C52) and cryptophycin 55 (C55) in sequential and simultaneous combination treatment regimens in human tumor xenografts models was explored. The antitumor activity of C52 and C55 was compared alone and in sequential combination with gemcitabine or paclitaxel in four lung cancer models, H460 and Calu-6 NSCLC and SW2 and H82 small cell lung carcinoma. The combination of C52 followed by gemcitabine was additive in three tumors and greater-than-additive in the fourth. The combination of C55 followed by gemcitabine was additive in three tumors and less-than-additive in the fourth. The combination of C52 followed by paclitaxel was greater-than-additive in one tumor, additive in one tumor and less-than-additive in two tumors. The combination of C55 followed by paclitaxel was greater-than-additive in two tumors and less-than-additive in two tumors. The simultaneous combination of C52 or C55 with fractionated radiation therapy was assessed in the H460 NSCLC tumor. Both cryptophycins produced a tumor response that was additive along with radiation therapy. The HCT116 colon carcinoma was used to compare the antitumor activity of simultaneous or sequential combination of 5-fluorouracil or irinotecan with C52. C52 produced greater-than-additive tumor response when administered either simultaneously with or sequentially with 5-fluorouracil or iriniotecan. Finally, when administered to animals bearing intraperitoneal OVCAR-3 ovarian carcinoma, C52, docetaxel and paclitaxel resulted in mean survival times of 123, 80 and 85 days compared with 72 days in the untreated controls. In combination with carboplatin, C52, docetaxel and paclitaxel resulted in mean survival times of 140, 105 and 135 days. Cryptophycins have the potential to be useful chemotherapeutic agents in a wide variety of clinical combinations regimens.     

Capecitabine: Preclinical Pharmacology Studies

Capecitabine (N⁴-pentyloxycarbonyl-5-deoxy-5-fluorocytidine) is a novel fluoropyrimidine carbamate, which was designed to besequentially converted to 5-fluorouracil (5-FU) by three enzymes located inthe liver and in tumors; the final step is the conversion of5-deoxy-5-fluorouridine (5-DFUR) to 5-FU by thymidine phosphorylase (dThdPase) in tumors. In human cancer xenograft models, capecitabine given orally yielded substantially higher concentrations of 5-FU within tumors than in plasma ornormal tissue (muscle). The tumor 5-FU levels were also much higherthan those achieved by intravenous administration of 5-FU at equitoxic doses.Capecitabine and its intermediates are not cytotoxic by themselves,but become effective after their conversion to 5-FU. This tumor selectivedelivery of 5-FU ensured greater efficacy and a more favorable safety profilethan with other fluoropyrimidines. In 24 human cancer xenograft modelsstudied, capecitabine was more effective at a wider dose range andhad a broader spectrum of antitumor activity than 5-FU, UFT or itsintermediate metabolite 5-DFUR. The susceptibility of the xenografts tocapecitabine correlated with tumor dThdPase levels. Moreover, theconversion of 5-DFUR to 5-FU by dThdPase in tumor was insufficient in axenograft model refractory to capecitabine. In addition, the efficacy ofcapecitabine was enhanced by dThdPase up-regulators, such astaxanes and cyclophosphamide. The efficacy of capecitabine may, therefore, beoptimized by selecting the most appropriate patient population based on dThdPasestatus and/or by combining it with dThdPase up-regulators. Capecitabinehas additional characteristics not found with 5-FU, such as potentantimetastatic and anticachectic actions in mouse tumor models.With this profile, capecitabine may have substantial potential in cancer treatment.     

Antitumor activity of a new orally active organotin compound: a preliminary study in murine tumor models

The toxicity and antitumor activity of the novel organotin compound triethyltin(IV)lupinylsulfide hydrochloride (IST-FS 29), administered by the oral route, have been evaluated against three transplantable murine tumor models: P388 lymphocytic leukemia, B16F10 melanoma and 3LL Lewis lung carcinoma. Mild and reversible signs of acute toxicity such as behavioral symptoms, weight loss and histological alterations were mainly reported at the highest single dose of 28 mg/kg. Conversely, lower concentrations of compound ranging from 7 to 21 mg/kg did not result in major toxic effects, even after repeated dosing. The antitumor activity studies showed that fractionation dosing, rather than single bolus administration, over 1 week, might prove more active and better tolerated by allowing the achievement of the highest therapeutic total dose of IST-FS 29 (42 mg/kg). Indeed, repeated administrations of IST-FS 29 resulted in marked significant improvement of antitumor activity against B16F10 (50% of tumor volume inhibition, p = 0.0003) and, to a greater extent, 3LL (90% of tumor volume inhibition, p = 0.0001) tumors. These results indicate that IST-FS 29 might be a suitable candidate as an orally administrable anticancer drug and support its further development in human tumor xenografts.     

Targeting the tumor vasculature: enhancing antitumor efficacy through combination treatment with ZD6126 and ZD6474

BACKGROUND: The antitumor efficacy of combination therapy of the vascular disrupting agent ZD6126 and antiangiogenic agent ZD6474 was evaluated in the models of human colorectal (HT29) and ovarian carcinoma (OW1). MATERIALS AND METHODS: HT29 and OW1 xenograft-bearing mice were treated with ZD6126 and ZD6474 either alone or in combination. ZD6126 therapy consisted of three doses of 100 mg/kg administered 1, 3 and 5 days after the tumor reached the starting size. ZD6474 was administered daily at a dose of 25 mg/kg on days 1-5. RESULTS: ZD6126 and ZD6474 treatment alone only resulted in modest tumor growth delay. However, significantly enhanced antitumor effects were observed in the combination treatment. CONCLUSION: The combination of the vascular disrupting with the antiangiogenic agent led to significant enhancement of antitumor efficacy in HT29 and OW1 human tumor models. Such combination therapy may have significant therapeutic benefit even in tumors insensitive to either treatment alone.     

Improved effectiveness of nanoparticle albumin-bound (nab) paclitaxel versus polysorbate-based docetaxel in multiple xenografts as a function of HER2 and SPARC status

Nanoparticle albumin-bound (nab)-paclitaxel (Abraxane) is an albumin-bound 130-nm particle form of paclitaxel that demonstrated higher efficacy and was well tolerated compared with solvent-based paclitaxel (Taxol) and docetaxel (Taxotere) in clinical trials for metastatic breast cancer. Nab-paclitaxel enhances tumor targeting through gp60 and caveolae-mediated endothelial transcytosis and the association with the albumin-binding protein SPARC (secreted protein, acidic and rich in cysteine) in the tumor microenvironment. The overexpression of human epidermal growth factor receptor-2 (HER2) in breast cancer has been shown to correlate with resistance to paclitaxel. To evaluate the importance of HER2 and SPARC status in determining the relative efficacy of nab-paclitaxel compared with polysorbate-based docetaxel, nude mice bearing six different human tumor xenografts were treated with nab-paclitaxel (MX-1: 15 mg/kg, once a week for 3 weeks; LX-1, MDA-MB-231/HER2+, PC3, and HT29: 50 and 120 mg/kg, every 4 days three times ; MDA-MB-231: 120 and 180 mg/kg, every 4 days three times) and polysorbate-based docetaxel (15 mg/kg). HER2 and SPARC status were analyzed by RT-PCR and immunohistochemical staining. MDA-MB-231 and MX-1 breast and LX-1 lung cancers were HER2 negative and low in SPARC expression. Nab-paclitaxel at submaximum-tolerated dosage was significantly more effective than polysorbate-based docetaxel at its maximum-tolerated dosage in these three HER2-negative tumors. The HER2-positive tumors had variable SPARC expression, with MDA-MB-231/HER2+ 相似文献   

Therapeutic targeting of the endothelin-A receptor in human ovarian carcinoma: efficacy of cytotoxic agents is markedly enhanced by co-administration with atrasentan

The endothelin-1/endothelin-A receptor autocrine pathway is overexpressed in ovarian carcinoma. We explored the efficacy of atrasentan (ABT-627), a small orally active endothelin- A receptor antagonist, in monotherapy and combination therapy on HEY ovarian carcinoma xenografts. Atrasentan (2 mg/kg per 24 hours i.p. for 21 days) induced similar inhibition of tumor growth as paclitaxel (20 mg/kg i.v. three times a day every 4 days) with a reduction of 65% compared to control. The co-administration of atrasentan enhanced the efficacy of cytotoxic agents, such as taxanes or platinum compounds. Administration of atrasentan in combination with paclitaxel caused a strong antitumor effect. Remarkably, four of ten mice bearing HEY xenografts had no histological evidence of tumors. Tumor growth inhibition was accompanied by a significant decrease of molecular effectors involved in angiogenesis and invasion and by enhanced tumor cell apoptosis. Moreover, although cisplatinum as a single agent (5 mg/kg i.p. on day 1) markedly inhibited HEY tumors, atrasentan was very effective in potentiating this effect, with partial or complete tumor regression. The antitumor, anti-angiogenic, and apoptotic activities obtained with atrasentan and the enhanced efficacy of cytotoxic agents provide a rationale for its clinical evaluation in ovarian carcinoma.     

Preoperative chemotherapy with epidoxorubicin, docetaxel and capecitabine plus pegfilgrastim in patients with primary breast cancer

The objective of this pilot trial was to evaluate the safety and activity profile of epidoxorubicin, docetaxel and oral capecitabine plus pegfilgrastim (TEX+P) as preoperative first-line treatment for patients with breast cancer. Eleven consecutive patients were enrolled in this prospective clinical pilot trial. Preoperative treatment consisted of epidoxorubicin [75 mg/m2 body surface area (BSA)] and docetaxel (75 mg/m2 BSA) administered sequentially on day 1 in combination with oral capecitabine 2000 mg/m2 daily divided into two doses on days 1-14 of each 3-week treatment cycle. Pegfilgrastim 6 mg fixed dose was administered s.c. on day 2 of every treatment cycle. Patients received a total of 58 cycles (median 6 cycles, range 1-6) of this therapeutic regimen. Outpatient TEX+P was well tolerated. No WHO grade IV toxicity was observed. A pathological major response to this preoperative therapy regimen could be demonstrated in eight of nine evaluable patients leading to breast-conserving surgery in seven of nine evaluable patients. We conclude that outpatient TEX+P is safe in the neoadjuvant treatment of patients with primary breast cancer. Thus, this regimen can be considered for further clinical trials.     

Amelioration of thrombocytopenia with concomitant ornithine in sarcomabearing rats receiving high dose difluoromethylornithine

Summary The dose limiting toxicity of difluoromethylornithine (DFMO), when administered by continuous infusion, is thrombocytopenia. DFMO-induced antitumor activity and thrombocytopenia were time- and dosedependent up to 1700 mg/kg/d when administered continuously for 12 days. Concomitant ornithine administration (at selected molar ratios to DFMO) ameliorated thrombocytopenia induced by DFMO at a dose of 2000 mg/kg/day without adversely affecting its antitumor activity. The purpose of this study was to determine if ornithine could ameliorate the thrombocytopenia of higher DFMO doses and increase the efficacy of DFMO. Fischer 344 male rats with a transplantable sarcoma in the right flank were given 2000 and 3500 mg/kg/d DFMO alone or with ornithine at a molar ratio of 0.4 for 8 days by continuous infusion. Concomitant ornithine infusion overcame the thrombocytopenia that was induced by either dose of DFMO without reducing the antitumor activity against the sarcoma. The antitumor activity, tumor polyamine levels, and tumor S-adenosylmethionine decarboxylase activity did not consistently change with increasing doses of DFMO or with the addition of ornithine to the infusion regimen. These results demonstrate that the thrombocytopenia induced by doses of DFMO greater than 2000 mg/kg/d can be ameliorated without compromising the antitumor activity. Address for offrints: V.B. Grossie, Jr. Department of General Surgery, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe, Houston, TX, 77030, USA     

Capecitabine: a review of its pharmacology and therapeutic efficacy in the management of advanced breast cancer

Capecitabine is an orally administered prodrug of fluorouracil which is indicated in the US and Europe, in combination with docetaxel, for the treatment of patients with metastatic breast cancer failing anthracycline therapy, and as monotherapy for metastatic breast cancer resistant to paclitaxel and anthracycline therapy (US) or failing intensive chemotherapy (Europe). Capecitabine is also approved for use in metastatic colorectal cancer. Capecitabine is metabolically activated preferentially at the tumour site, and shows antineoplastic activity and synergy with other cytotoxic agents including cyclophosphamide or docetaxel in animal models. Bioavailability after oral administration is close to 100%. In patients with pretreated advanced breast cancer, capecitabine is effective as monotherapy and also in combination with other agents. Combination therapy with capecitabine 1,250 mg/m(2) twice daily for 2 weeks of every 3-week cycle plus intravenous docetaxel 75 mg/m(2) on day one of each cycle was superior to intravenous monotherapy with docetaxel 100 mg/m(2) on day one of each cycle. Capecitabine plus docetaxel significantly reduced the risks of disease progression and death by 35% (p = 0.0001) and 23% (p < 0.05), respectively, and significantly increased median survival (p < 0.05) and objective response rates (p < 0.01). Efficacy has also been demonstrated with capecitabine monotherapy and combination therapy in previously untreated patients in preliminary trials. The most common adverse effects occurring in patients receiving capecitabine monotherapy include lymphopenia, anaemia, diarrhoea, hand-and-foot syndrome, nausea, fatigue, hyperbilirubinaemia, dermatitis and vomiting (all >25% incidence). While gastrointestinal events and hand-and-foot syndrome occurred more often with capecitabine than with paclitaxel or a regimen of cyclophosphamide, methotrexate and fluorouracil (CMF), neutropenic fever, arthralgia, pyrexia and myalgia were more common with paclitaxel, and nausea, stomatitis, alopecia and asthenia were more common with CMF. The incidence of adverse effects and hospitalisation was similar in patients receiving capecitabine plus docetaxel and those receiving docetaxel monotherapy. In conclusion, capecitabine, an oral prodrug of fluorouracil which is activated preferentially at the tumour site, is an effective and convenient addition to the intravenous polychemotherapeutic treatment of advanced breast cancer in pretreated patients, and also has potential as a component of first-line combination regimens. Combined capecitabine plus docetaxel therapy resulted in similar rates of treatment-related adverse effects and hospitalisation to those seen with docetaxel monotherapy. Capecitabine is also effective as monotherapy in pretreated patients and phase II data for capecitabine as first-line monotherapy are also promising. While gastrointestinal effects and hand-and-foot syndrome occur often with capecitabine, the tolerability profile was comparatively favourable for other adverse effects (notably, neutropenia and alopecia).     

Anticancer activity of stabilized palifosfamide in vivo: schedule effects, oral bioavailability, and enhanced activity with docetaxel and doxorubicin

Palifosfamide, the DNA-alkylating metabolite of ifosfamide (IFOS), has been synthesized as a stabilized tris or lysine salt and found to have preclinical and clinical antitumor activity. Stabilized palifosfamide overcomes limitations of IFOS because of patient-to-patient variability in response resulting from variable prodrug activation, resistance and toxicities of metabolic byproducts, acrolein and chloroacetaldehyde. Palifosfamide represents an effective alternative to IFOS and other DNA-alkylating prodrugs. The antitumor activities of stabilized palifosfamide were investigated in vivo. Dose response, route and schedule of administration, and interaction with docetaxel or doxorubicin were investigated in NCr-nu/nu mice bearing established orthotopic mammary MX-1 tumor xenografts. Oral activity was investigated in P388-1 leukemia in CD2F1 mice. Oral and intraperitoneal bioavailabilities were compared in Sprague-Dawley rats. Stabilized palifosfamide administered by optimized regimens suppressed MX-1 tumor growth (P<0.05) by greater than 80% with 17% complete antitumor responses and up to three-fold increase in time to three tumor doublings over controls. Median survival in the P388-1 (P<0.001) model was increased by 9 days over controls. Oral bioavailability in rats was 48-73% of parenteral administration, and antitumor activity in mice was equivalent by both routes. Treatment with palifosfamide-tris combined with docetaxel or doxorubicin at optimal regimens resulted in complete tumor regression in 62-75% of mice. These studies support investigation of stabilized palifosfamide in human cancers by parenteral or oral administration as a single agent and in combination with other approved drugs. The potential for clinical translation of the cooperative interaction of palifosfamide-tris with doxorubicin by intravenous administration is supported by results from a recent randomized Phase-II study in unresectable or metastatic soft-tissue sarcoma.     

Nontoxic Suramin Treatments Enhance Docetaxel Activity in Chemotherapy-Pretreated Non-Small Cell Lung Xenograft Tumors

Purpose We reported that nontoxic suramin treatments enhance the activity of chemotherapy in preclinical models, a finding supported by the results of subsequent phase I/II trials in chemotherapy-naive non-small cell lung cancer (NSCLC) patients who received/carboplatin (P/C) combination therapy. The present study evaluated whether suramin enhances the activity of docetaxel in human NSCLC xenografts.Methods The in vitro effect of suramin on docetaxel activity was evaluated using 3-D histocultures of chemotherapy-naive A549 tumors. For in vivo activity evaluation, we first established the P/C pretreatment schedule that produced tumor growth inhibition, but not tumor eradication, and established the maximally tolerated docetaxel/suramin regimens. In the second study, P/C-treated animals received physiological saline, single-agent suramin (10 mg/kg), docetaxel (10 mg/kg), or the combination twice weekly for 3 weeks.Results The in vitro results showed that 20 μM suramin, which had no activity as single agent, enhanced the docetaxel activity (measured as 50% inhibition of DNA synthesis) by more than 10-fold. The in vivo studies showed reduced tumor growth by P/C (30% growth in 14 days vs. 75% in control). In contrast, docetaxel produced tumor regression (15% reduction) in P/C-treated animals, significantly reduced, on a cellular level, the viable cell density and the proliferating fraction (40% reduction for both measurements), and enhanced the apoptotic fraction 4-fold (p < 0.05 for all effects). Suramin had no activity or toxicity (measured as body weight loss) but significantly enhanced the docetaxel activity. Compared to docetaxel alone, the combination showed earlier onset of tumor size reduction, greater extent of tumor regression (31 vs. 15%), greater reduction of viable cell density and proliferating fraction (additional 15–25% reduction), and greater apoptotic fraction (additional 2.5-fold increase) (p < 0.05 for all parameters).Conclusions Results of the present study indicate that nontoxic suramin treatments enhanced the activity of docetaxel in P/C-pretreated A549 xenograft tumors in mice without enhancing host toxicity. These encouraging results provided the basis for phase I/II trials of docetaxel plus low-dose suramin in patients with NSCLC in second-/third-line settings.     

A novel plasmin-inhibitor inhibits the growth of human tumor xenografts and decreases metastasis number

The novel plasmin inhibitor YO-2, which also exerts an apoptosis-inducing effect on various human tumor cell cultures, was examined regarding its tumor growth inhibitory and antimetastatic action. The tumor growth inhibitory effect of YO-2 was studied using HT-29 human colon carcinoma, HT-18 human melanoma and HT-58 human B cell lymphoma inoculated as xenografts into immuno-deprived mice. Antimetastatic activity was tested on the B16 mouse melanoma muscle-lung model. YO-2 inhibited the growth of all xenografts in the range of 40-50%, when administered s.c. at a dose of 2.0 mg/kg (HT-29, HT-58) or orally at a dose of 0.4 mg/kg (HT-18). YO-2 decreased the number of lung metastasis found in mice inoculated i.m. with B16 melanoma, 4 mg/kg being the most effective. Since YO-2 is the only plasmin inhibitor having antihemorrhagic and also antitumor effect, this compound could be rationally used in combination therapy of neoplastic disease, especially when hemorrhage aggravates the course of the disease.     

A Physiologically Based Pharmacokinetic Analysis of Capecitabine,a Triple Prodrug of 5-FU,in Humans: The Mechanism for Tumor-Selective Accumulation of 5-FU

Purpose. To identify the factors governing the dose-limiting toxicity in the gastrointestine (GI) and the antitumor activity after oral administration of capecitabine, a triple prodrug of 5-FU, in humans. Method. The enzyme kinetic parameters for each of the four enzymes involved in the activation of capecitabine to 5-FU and its elimination were measured experimentally in vitro to construct a physiologically based pharmacokinetic model. Sensitivity analysis for each parameter was performed to identify the parameters affecting tissue 5-FU concentrations. Results. The sensitivity analysis demonstrated that (i) the dihydropyrimidine dehydrogenase (DPD) activity in the liver largely determines the 5-FU AUC in the systemic circulation, (ii) the exposure of tumor tissue to 5-FU depends mainly on the activity of both thymidine phosphorylase (dThdPase) and DPD in the tumor tissues, as well as the blood flow rate in tumor tissues with saturation of DPD activity resulting in 5-FU accumulation, and (iii) the metabolic enzyme activity in the GI and the DPD activity in liver are the major determinants influencing exposure to 5-FU in the GI. The therapeutic index of capecitabine was found to be at least 17 times greater than that of other 5-FU-related anticancer agents, including doxifluridine, the prodrug of 5-FU, and 5-FU over their respective clinical dose ranges. Conclusions. It was revealed that the most important factors that determine the selective production of 5-FU in tumor tissue after capecitabine administration are tumor-specific activation by dThdPase, the nonlinear elimination of 5-FU by DPD in tumor tissue, and the blood flow rate in tumors.     

A phase I and pharmacokinetic study of the nonpolyglutamatable thymidylate synthase inhibitor ZD9331 plus docetaxel in patients with advanced solid malignancies

PURPOSE: To assess the feasibility of administering ZD9331, a thymidylate synthase (TS) inhibitor that does not undergo polyglutamation and has broad antitumor activity, in combination with docetaxel in patients with advanced solid malignancies. The study also sought to determine the principal toxicities of the regimen and recommend appropriate doses for phase II studies, characterize the pharmacokinetics of the agents, evaluate the possibility of major drug-drug interactions, and seek preliminary evidence of anti-cancer activity. PATIENTS AND METHODS: Patients with advanced solid malignancies were treated with escalating doses of docetaxel as a 60-minute intravenous (IV) infusion followed 30 minutes later by ZD9331 as a 30-minute IV infusion every 3 weeks. At least three patients were treated at each dose level, and the maximum tolerated dose level was defined as the highest dose level that was not associated with an unacceptably high incidence of severe toxicity. The pharmacokinetics of both ZD9331 and docetaxel were also characterized. RESULTS: Nineteen patients were treated with 71 cycles of ZD9331 and docetaxel (ZD9331/docetaxel) at dose levels that encompassed dosing iterations of ZD9331 ranging from 65 to 260 mg/m(2) and docetaxel doses in the range of 50 to 75 mg/m(2). Neutropenia was the principal toxicity of the ZD9331/docetaxel regimen. Since five of six patients treated at the ZD9331/docetaxel dose-level of 260/60 mg/m(2) had grade 4 neutropenia that was brief and uncomplicated in the first course, a rigorous exploration of higher dose levels was not undertaken. Nonhematologic toxicities, consisting of malaise, diarrhea, rash, nausea, and vomiting, were also observed, but these effects were rarely severe. No major antitumor responses were observed. The pharmacokinetics of both ZD9331 and docetaxel were similar to those reported in previous studies of each agent administered alone, suggesting the lack of major drug-drug interactions. CONCLUSION: The combination regimen, consisting of ZD9331 and docetaxel, is feasible and well tolerated at single-agent doses that are clinically-relevant. This ZD9331/docetaxel regimen does not appear to be associated with either major pharmacokinetic or toxicologic drug-drug interactions. A ZD9331/docetaxel dose level of 260/60 mg/m(2) is recommended as an initial dose level in disease-directed studies of the regimen, with further dose escalation of docetaxel to 75 mg/m(2) if the initial treatment is well tolerated. Further studies with this regimen are warranted in tumor types that have demonstrated sensitivity to both agents.     

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

Summary 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 ipimplanted 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.