Antitumor Activity Of Docetaxel Research Articles

A Novel Encapsulation Approach to Enhance the Delivery and Antitumor Activity of Docetaxel in Breast Cancer Therapy

Docetaxel (DTX) is one of the most potent anticancer drugs but its extensive side effects necessitate innovative formulations. In this study, we aimed to investigate the expression pattern of apoptotic proteins, cell cycle arrest, and apoptosis induction after treatment with encapsulated DTX in alginate-chitosan nanoparticles in both breast cancer cells (MCF-7) and peripheral blood mononuclear cells (PBMCs). The characterization of the nanoparticles revealed a spherical shape with a size <50 nm, a hydrodynamic diameter of 200 nm, a Polydispersity Index of 0.5, and an encapsulation efficiency of 98.75%. The free drug was released completely within 11 h while encapsulated DTX was released only 34% in 96 h. The encapsulated drug indicated higher cytotoxicity on MCF-7 cells and the half inhibitory concentration (IC50) value was 2 µg/ml after 72 h. Quantitative real-time PCR demonstrated a significant increase in cell death as the expression of apoptosis regulatory protein (Bcl-2) was downregulated with no impact on Bax in the MCF-7 cells. A notable decrease in the expression pattern of pro-inflammatory cytokine (IL-1β) in PBMCs indicated less inflammation induction. Flow cytometry analysis revealed that the newly formulated drug induced less opoptosis in PBMCs than the free DTX. Cell cycle arrest in the sub-G1 phase was observed for the free drug while the encapsulated drug exhibited no significant changes. Our results suggest the high toxicity of the formulated drug in contrast to the free DTX on the MCF-7 cell line, minimal blood cell side effects, and no inflammation positioning it as a promising alternative to free docetaxel.

A Multicenter Study of Docetaxel at a Dose of 100 mg/m2 in Japanese Patients with Advanced or Recurrent Breast Cancer.

Objective This study examined the pharmacokinetics, safety and anti-tumor activity of docetaxel at a dose of 100 mg/m2 in Japanese patients with advanced or recurrent breast cancer. Methods Japanese patients with advanced or recurrent breast cancer received docetaxel at a dose of 100 mg/m2 intravenously every three weeks. The pharmacokinetics were assessed during the first cycle. The patients were allowed to receive supportive care drugs based on the indications and dosages in Japan. Results Six eligible patients aged 39-65 years old and 27 treatment cycles were analyzed. All patients experienced one or more adverse events (AEs). The common AEs were neutropenia, thrombocytopenia, alopecia, rash, diarrhea, neuropathy (sensory), fatigue, nausea, fever, hypoalbuminemia, alanine transaminase (ALT) increased, constipation, and taste alteration. Grade 3 or 4 AEs included neutropenia, leukopenia, anemia, lymphopenia, decreased appetite, γ-glutamyl transpeptidase (GTP) increased, aspartate transaminase (AST) increased, ALT increased, hypertension and cellulitis which were all reversible. There were no cases of febrile neutropenia, serious AEs or deaths. The median number of cycles was six. Dose reductions were not observed and most cycles were administered at their intended doses. No complete response and three partial responses were observed in four assessable patients with evaluable lesions. The maximum concentration and area under the blood concentration-time curve were 3,417.5 ng/mL and 4.35 μg・hr/mL (mean), respectively. Conclusion Docetaxel at a dose of 100 mg/m2 was tolerable with acceptable safety profiles and effective for Japanese patients with advanced or recurrent breast cancer with appropriate supportive therapies, and pharmacokinetic (PK) profiles which corresponded approximately with the findings of previous clinical studies.

IAP antagonism enhances anti-tumor activity of docetaxel or panobinostat in ovarian cancer cell lines

IAP antagonism enhances anti-tumor activity of docetaxel or panobinostat in ovarian cancer cell lines

Engineering of Biocompatible pH-Responsive Nanovehicles from Acetalated Cyclodextrins as Effective Delivery Systems for Tumor Therapy.

There is still an unmet demand for materials with excellent biocompatibility, controlled hydrolytic capability, and elegant responsiveness to chemical or physical stimuli. To engineer biocompatible materials from β-cyclodextrin (β-CD), in this study, we synthesized acetalated β-CDs (Ac-βCDs) by one-pot acetalation using 2-ethoxypropene as an acetonation reagent, which can be further processed into nanoparticles (NPs) via the emulsion technique. Ac-βCD NPs showed pH-labile hydrolysis and pH-triggered release of docetaxel (DTX) payload. Both properties were mainly dominated by the molar ratio of linear to cyclic acetal, which can be conveniently modulated by the acetalation time used for materials synthesis. Ac-βCD NPs were found to be biocompatible in both in vitro cell culture and in vivo acute toxicity evaluations following intravenous injection. In vitro cell culture experiments demonstrated that antitumor activity of DTX against both sensitive and resistant cancer cells was remarkably improved by formulation into Ac-βCD nanomedicines. In vivo antitumor study also substantiated the dramatically enhanced efficacy of DTX/Ac-βCD NPs in a melanoma-bearing nude mouse model. These studies demonstrated that NPs derived from Ac-βCDs may serve as biocompatible and effective carriers for drug delivery.

In vivo assessment of the therapeutic effects of lyophilized leech saliva extract from (Huridinaria manillensis) on LNCaP tumor xenograft model in nude mice.

271 Background: Ancient traditional physicians from many countries used leeching to treat a wide range of diseases for thousands of years. A large number of peptides and proteins have been identified and characterized in leech saliva extract (LSE), including anti-thrombotic agents, cancer metastasis inhibitors and anti-microbials Currently, leech therapy is established as an important tool in microsurgery and reconstructive operations having demonstrated superior clinical outcomes for the optimal salvage of grafted tissues. Methods: In the current study, we have determined the in vivo efficacy of LSE from (Huridinaria manillensis) on castration resistant LNCaP xenograft mouse model. Mice were divided into three groups of six, mice were subcutaneously injected with either LSE (5 mg/kg), docetaxel (10 mg/kg), or vehicle once a week. PSA and tumor volume were measured weekly. After four weeks of treatment, mice were euthanized, tumors and organs were collected for transcriptome and immunohistochemical (IHC) analysis. Results: There was a significant decrease in the tumor volume and PSA with either docetaxel (10mg/kg) or LSE (5 mg/kg) treated groups compared to the control. While there was no significant difference between the anti-tumor activity of docetaxel (10mg/kg) and LSE (5 mg/kg). IHC showed significant increase in caspase-3 and significant decrease in Ki-67 and PCNA expression in the LSE treated mice compared to the control group. Interestingly, transcriptome analysis of tumor samples showed that LSE modulated cytokine production, monocyte adhesion, steroidogenesis, and P38 MAPK signaling pathways. Conclusions: LSE has significant anti-tumor activity in LNCaP tumor xenograft models with no apparent side effects. This can be attributed, at least partly, to its inhibition of cellular proliferation, induction of apoptosis, modulation of immunity and steroidogenesis.

Salvage chemotherapy with docetaxel and pegylated liposomal doxorubicin in pretreated patients with platinum- and taxane-sensitive ovarian cancer: a multicenter phase II trial of the Hellenic Oncology Research Group (HORG)

To evaluate the safety and antitumor activity of docetaxel (DOC) and pegylated liposomal doxorubicin (PLD) combination in patients with platinum- and taxane-sensitive ovarian cancer. Twenty-three patients were enrolled. DOC was administered at the dose of 40 mg/m(2) intravenously (i.v.) and PLD at 20 mg/m(2) i.v. on days 1 and 15 in cycles of 28 days. The study was closed prematurely due to slow accrual. Seven (30.4 %) patients achieved objective response (three complete, four partial), while five (21.7 %) others experienced stable disease (overall disease control rate 52.1 %). The median progression-free survival was 4.8 months and the median overall survival 18.8 months. Grade 3-4 neutropenia occurred in two (8.7 %) and one (4.3 %) patients, respectively. Febrile neutropenia occurred in two patients. The most common non-hematological grade 3 toxicity was hand-foot syndrome (13 % of patients). There was no treatment-related death. The combination of pegylated liposomal doxorubicin and docetaxel is a well tolerated and a relatively active regimen in pretreated patients with platinum- and taxane-sensitive advanced ovarian cancer.

Curcumin Enhances Docetaxel-Induced Apoptosis of 8505C Anaplastic Thyroid Carcinoma Cells.

BackgroundAnaplastic thyroid cancer (ATC) is one of the most aggressive malignancies in humans, and its progression is poorly controlled by existing therapeutic methods. Curcumin has been shown to suppress inflammation and angiogenesis. In this study, we evaluated whether curcumin could augment docetaxel-induced apoptosis of ATC cells. We also analyzed changes in nuclear factor κB (NF-κB) and cyclooxygenase-2 (COX-2) expression levels to delineate possible mechanisms of their combined action.MethodsATC cells were cultured and treated with curcumin and docetaxel alone or in combination. The effects on cell viability were determined by MTS assay. Apoptosis was assessed by annexin V staining and confirmed by flow cytometric analysis. Caspase, COX-2, NF-κB levels were assayed by Western blotting.ResultsCurcumin combined with docetaxel led to lower cell viability than treatment with docetaxel or curcumin alone. Annexin V staining followed by flow cytometric analysis demonstrated that curcumin treatment enhanced the docetaxel-induced apoptosis of ATC cells. Additionally, curcumin inhibited docetaxel-induced p65 activation and COX-2 expression.ConclusionWe conclude that curcumin may enhance docetaxel's antitumor activity in ATC cells by interfering with NF-κB and COX-2. Our results suggest that curcumin may emerge as an attractive therapeutic candidate to enhance the antitumor activity of taxanes in ATC treatment.

Abstract P4-15-02: The PI3K inhibitor GDC-0032 enhances the efficacy of standard of care therapeutics in PI3K alpha mutant breast cancer models

Abstract The phosphoinositide 3-kinases (PI3Ks) are lipid kinases that activate the PI3K signaling pathway and play an essential role in regulating breast tumor cell growth, migration, and survival. Activating and transforming mutations in the PIK3CA gene (PI3K alpha) are commonly found in HER2+ breast cancer and ER+ breast cancer. GDC-0032 is a selective, orally bioavailable inhibitor with a Ki of 0.29 nM for PI3K alpha with 30 fold less inhibition of PI3K beta. In addition, GDC-0032 has increased single agent activity against PI3K alpha mutant and HER2 amplified cancer models in vitro and in vivo. The aim of our study was to evaluate the efficacy of GDC-0032 in breast cancer models in combination with standard of care therapeutics including taxanes, endocrine therapies, and HER2 targeted therapies. We evaluated cell viability for a range of dose concentrations of GDC-0032, as single agent and in combinations, in eleven breast cancer cell lines that harbor mutations in PI3K alpha (K111N, E545K, H1047R) and/or over-expressed HER2. GDC-0032 was combined with taxanes (paclitaxel and docetaxel), endocrine therapies (fulvestrant and tamoxifen) or anti-HER2 agents (trastuzumab, pertuzumab or ado-trastuzumab-emtansine) and synergy quantified using the Chou and Talalay method of Combination Index (C.I.). The combination of GDC-0032 with taxanes, endocrine therapies or anti-HER2 therapies were synergistic in the breast cancer cell lines tested based on C.I. values of less than 1.0. The combination of GDC-0032 with docetaxel in vitro resulted in decreased viability as a result of increased cell death. The in vitro results translated in vivo as GDC-0032 enhanced the anti-tumor activity of docetaxel and paclitaxel in MCF7 (E545K) xenografts that resulted in increased tumor regressions when GDC-0032 was dosed daily or intermittently on the same schedule as the taxane. In addition, the combination of GDC-0032 and fulvestrant or tamoxifen resulted in greater efficacy in the MCF7 xenograft model when compared to either agent alone. Enhanced efficacy was also observed when GDC-0032 was combined with trastuzumab or ado-trastuzumab-emtansine in the HER2+ BT474M1 (K111N) xenograft model. Moreover, the triple combinations of GDC-0032/trastuzumab/pertuzumab or GDC-0032/trastuzumab/docetaxel resulted in durable tumor regressions that were sustained in the HER2+ KPL-4 (H1047R) and BT474M1 xenograft models, respectively. All drug combinations with GDC-0032 were well tolerated in vivo based on minimal changes in body weight. Collectively, our preclinical data demonstrate that GDC-0032 enhances the efficacy of standard of care therapeutics in PI3K alpha mutant breast cancer models and provides a strong rationale for further evaluation in patients. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-15-02.

Combined Inhibition of Epidermal Growth Factor Receptor and Cyclooxygenase-2 Leads to Greater Anti-tumor Activity of Docetaxel in Advanced Prostate Cancer

The epidermal growth factor receptor (EGFR) and cyclooxygenase-2(COX-2) play a critical role in disease progression, relapse and therapeutic resistance of advanced prostate cancer (PCa). In this paper, we evaluated, for the first time, the therapeutic benefit of blocking EGRF and/or COX-2 (using gefitinib and NS-398, respectively) in terms of improving the efficacy of the conventional clinical chemotherapeutic drug docetaxel in vitro and vivo. We showed that EGFR and COX-2 expression was higher in metastatic than non-metastatic PCa tissues and cells. Docetaxel, alone or in combination with gefitinib or NS-398, resulted in a small decrease in cell viability. The three drug combination decreased cell viability to a greater extent than docetaxel alone or in combination with gefitinib or NS-398. Docetaxel resulted in a modest increase in apoptotic cell in metastatic and non-metastatic cell lines. NS-398 markedly enhanced docetaxel-induced cell apoptosis. The combination of the three drugs caused even more marked apoptosis and resulted in greater suppression of invasive potential than docetaxel alone or in association with gefitinib or NS-398. The combination of all three drugs also resulted in a more marked decrease in NF-ΚB, MMP-9 and VEGF levels in PC-3M cells. These in vitro findings were supported by in vivo studies showing that docetaxel in combination with gefitinib and NS-398 was significantly more effective than any individual agent. Based on previous preclinical research, we conclude that simultaneously blocking EGFR and COX-2 by gefitinib and NS-398 sensitizes advanced PCa cells to docetaxel-induced cytotoxicity.

A randomized open-label phase II study evaluating antitumor activity of the survivin antisense oligonucleotide LY2181308 (LY) in combination with docetaxel (DO) for second-line treatment of patients with non-small cell lung cancer (NSCLC) using change in tumor size (CTS).

8051^ Background: Resistance to chemotherapy in progressive NSCLC is associated with overexpression of antiapoptotic proteins including survivin. Down-regulation of survivin can sensitize NSCLC to DO in vitro and in xenograft studies. On the basis of preclinical/phase I results we examined antitumor activity of DO+LY compared with DO alone. Methods: Key eligibility criteria: ECOG PS 0-1, stage IIIB/IV NSCLC all histologies, progression after first-line platinum regimen. Patients randomized (N=180) 2:1 to receive DO+LY (LY 750 mg IV loading ×3, Q1W maintenance) or DO alone (75 mg/m2 D1Q3W) until progression/toxicities. Antitumor activity was compared using CTS from baseline to end of cycle (C) 2 in each arm. This analysis, which uses tumor measurements as a continuous variable rather than a categorical endpoint based on RECIST, increases statistical efficiency and enables early assessment of clinical benefit. Secondary objectives included assessment of toxicity, PK, PFS and OS. Results: 114 patients received study drug and were included in the analyses. Baseline patient demographics were similar. No statistically significant difference in mean CTS ratio at C2 or in PFS was observed between the 2 arms: CTS was 1.07 with LY+DO (SD, 0.28) and 1.04 with DO (SD, 0.28); median PFS was 2.83 mo (95% CI, 1.84–3.65) with LY+DO and 3.35 mo (95% CI, 2.69–4.57) with DO (log-rank p=0.191). However, Cox regression revealed CTS to be a statistically significant factor for PFS: decreased CTS was associated with increased PFS (HR 0.45; 95% CI, 0.30–0.68, p=0.0001). Median OS was 7.9 mo (90% CI, 6.6–9.7) with LY+DO and 8.8 mo (90% CI, 5.7–13.8) with DO (log-rank p=0.481). There were no differences in toxicities or other secondary parameters. Incidence of grade III/IV toxicities was similar in both arms and was consistent with the known profile of LY+DO as was the PK profile. Conclusions: Addition of LY to DO did not improve the antitumor activity of DO. CTS appears to be a useful endpoint in phase II studies and should be considered further as an endpoint for early decision-making. Clinical trial information: NCT01107444.

99 Smac Mimetic SM-406 Targets Prostate Cancer Tumor Initiating Cells and Enhances the Antitumor Activity of Docetaxel in Vivo

99 Smac Mimetic SM-406 Targets Prostate Cancer Tumor Initiating Cells and Enhances the Antitumor Activity of Docetaxel in Vivo

Abstract 937: Dose-banding of docetaxel in MT-3 tumor bearing nude mice

Abstract Background: Body surface area (BSA)-based dosing of chemotherapy has a number of limitations and - this coupled with a need to improve production efficiencies in hospital pharmacy compounding units - led to the development of dose-banding in a ±5% range around BSA. However, there is a paucity of data on the impact of dose-banding on clinical outcomes. In addition, it is unknown whether variations above 5% have an impact on chemotherapy-associated toxicity or anti-tumor activity. Therefore, the aim of the present study was to investigate the impact of dose-banding, with variations from the calculated dose ≤ 5%, on antitumor activity of docetaxel using a mouse xenograft model. Materials and methods: Female nude mice NMRI:nu/nu aged 6 to 8 weeks received s.c. implants of 5x106 cells (human breast cancer MT-3) on study day 0. Experiment 1: Six groups of 13-14 mice received on day 7 a single i.v. injection (200µl/20g mouse) with either vehicle (saline:polysorbate 80:EtOH at 1:0.5:0.5), the maximum tolerated dose of docetaxel (DocMTD, 25 mg/kg), or ±5% and ±7.5% MTD. Experiment 2: All animals (n=13-14/group) received i.v. injections on study days 8 and 22 with vehicle, or DocMTD, ±10%, ±15%, ±30% and ±80% MTD. Results: In the first experiment, tumor volume of the vehicle group increased ∼21-fold during the 28 days observation period, whereas treatment with DocMTD resulted in a 36% tumor volume reduction. Variations of the MTD up to ±7.5% showed no significant effect on the mean tumor volume in comparison to the DocMTD group (21-36% tumor growth reduction). Body weight decreased transiently in response to all docetaxel treatments (up to 14%, nadir 7-8 days after injection). In the second experiment, tumor growth rate of the vehicle group was comparable to the first study and administration of DocMTD resulted in 65% decreased tumor growth at day 28. At MTD +10% to +30% the tumor volume was 68% and 74% reduced vs. vehicle control group. At +80% (45 mg/kg) the tumor volumes were significantly lower after treatment (88% reduction vs. vehicle). No dose-related increase in tumor volume was observed for the -10 to -30% docetaxel-treated animals compared to the DocMTD group (mean tumor growth reduction 55% to 66% vs. vehicle). At -80% (5 mg/kg), tumor growth was comparable to vehicle-treated animals and reached a similar absolute volume at the end of the study. Conclusions: In the single-dose study, variations of up to ±7.5% from the calculated dose had no effect on tumor volume. In the repeat-dose study, doses of MTD ±30% resulted in similar efficacy on tumor volume. These data suggest that dose-banding with variations of greater than the currently accepted 5% is possible without affecting the efficacy of docetaxel. The potential impact of this finding on clinical practice may be a simplification of dose preparation in pharmacy, reduced drug wastage, as well as an improvement in the oncology service and patient experience. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 937. doi:1538-7445.AM2012-937

Abstract 3492: γ-secretase inhibitor PF-03084014 diminishes the tumor-initiating cells and demonstrates synergy with docetaxel in breast cancer xenograft models

Abstract Notch signaling is known to be a survival pathway for tumor-initiating cells. In this report, we demonstrate that the γ-secretase inhibitor PF-03084014 significantly enhances the antitumor activity of docetaxel in multiple xenograft models of triple-negative breast cancer. Mechanistic evaluation revealed that PF-03084014 perturbs the Notch signaling pathway and suppresses the function of tumor initiating cells (TIC). In MDA-MB-231Luc model, treatment of docetaxel led to a significant increase of CD133+/CD44+ and ALDH+ subpopulations by FACS analysis. In combination with PF-03084014, these two unique cell subpopulations were significantly diminished. Correspondingly, the functional analyses by tumor re-implant and mammosphere-forming efficiency assays revealed that docetaxel-therapy promoted the tumor initiating capability of the remaining cells, in which an increased stem cell property and Notch pathway activation were observed through gene signature changes. In contrast, PF-03084014 co-treatment with docetaxel substantially hampered the self-renewal ability of these cells. Notch target gene analysis demonstrated the biological relevance of PF-03084014-induced activity. To characterize the function of CD133+/CD44+ subpopulation, MDA-MB-231Luc tumors were de-bulked by the treatment with docetaxel. Subsequently, the CD133+/CD44+ and CD133-/CD44- subpopulatons were isolated and re-implanted in SCID-bg mice using a limiting dilution approach. The results showed that CD133+/CD44+ cells gave rise to tumors with a 100 % take rate (10/10), whereas CD133-/CD44- cells were not tumorgenic (0/10). In addition, CD133+/CD44+ cells exhibited much higher tumorigenicity compared with the respective adherent parental cell line. PF-03084014 treatment caused a significant delay of CD133+/CD44+ tumor growth. The ability of PF-03084014 to suppress TICs was also observed in other breast cancer xenografts, including patient derived models. This data suggests that anti-TIC is one of the contributing mechanisms for the synergistic activities of PF-03084014 in combination with docetaxel. Our work provides potential therapeutic opportunities for PF-03084014 to improve conventional cytotoxic therapy by inhibiting Notch signaling in tumor-initiating cells and other bulk tumor cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3492. doi:1538-7445.AM2012-3492

TH-302, a hypoxia-activated prodrug with broad in vivo preclinical combination therapy efficacy: optimization of dosing regimens and schedules

Subregional hypoxia is a common feature of tumors and is recognized as a limiting factor for the success of radiotherapy and chemotherapy. TH-302, a hypoxia-activated prodrug selectively targeting hypoxic regions of solid tumors, delivers a cytotoxic warhead to the tumor, while maintaining relatively low systemic toxicity. The antitumor activity, different dosing sequences, and dosing regimens of TH-302 in combination with commonly used conventional chemotherapeutics were investigated in human tumor xenograft models. Seven chemotherapeutic drugs (docetaxel, cisplatin, pemetrexed, irinotecan, doxorubicin, gemcitabine, and temozolomide) were tested in combination with TH-302 in eleven human xenograft models, including non-small cell lung cancer (NSCLC), colon cancer, prostate cancer, fibrosarcoma, melanoma, and pancreatic cancer. The antitumor activity of docetaxel, cisplatin, pemetrexed, irinotecan, doxorubicin, gemcitabine, and temozolomide was increased when combined with TH-302 in nine out of eleven models tested. Administration of TH-302 2-8h prior to the other chemotherapeutics yielded superior efficacy versus other sequences tested. Simultaneous administration of TH-302 and chemotherapeutics increased toxicity versus schedules with dosing separations. In a dosing optimization study, TH-302 administered daily at 50mg/kg intraperitoneally for 5days per week in the H460 NSCLC model showed the optimal response with minimal toxicity. TH-302 enhances the activity of a wide range of conventional anti-neoplastic agents in a broad panel of in vivo xenograft models. These data highlight in vivo effects of schedule and order of drug administration in regimen efficacy and toxicity and have relevance to the design of human regimens incorporating TH-302.

248. Augmentation of Docetaxel Anti-tumor Activity by a Stathmin-Specific Bi-Functional shRNA

248. Augmentation of Docetaxel Anti-tumor Activity by a Stathmin-Specific Bi-Functional shRNA

Continuous and intermittent dosing of lonafarnib potentiates the therapeutic efficacy of docetaxel on preclinical human prostate cancer models

Lonafarnib is a potent, selective farnesyltransferase inhibitor (FTI) undergoing clinical studies for the treatment of solid tumors and hematological malignancies. Preclinically, a number of FTIs, including lonafarnib, interact with taxanes to inhibit cancer cell growth in an additive/synergistic manner. These observations provided rationale for investigating the effects of combining lonafarnib and docetaxel on preclinical prostate cancer models. To date, docetaxel is the only chemotherapeutic agent in clinical use for hormone-refractory prostate cancer. In vitro experiments with 22Rv1, LNCaP, DU-145, PC3 and PC3-M prostate cancer cell lines showed significantly enhanced inhibition of cell proliferation and apoptosis when lonafarnib was added to docetaxel. In human tumor xenograft models, continuous coadministration of lonafarnib with docetaxel caused marked tumor regressions (24-47%) in tumors from all of the cell types as well as parental CWR22 xenografts. Intermittent dosing of lonafarnib (5 days on then 5 days off) coadministered with docetaxel produced similar regressions in hormone-refractory 22Rv1 tumors. 22Rv1 tumors progressing on docetaxel treatment also responded to treatment with intermittent lonafarnib (5 days on then 5 days off). Moreover, animals did not exhibit any signs of toxicity during coadministration of lonafarnib and docetaxel. In conclusion, coadministration of continuous and intermittent lonafarnib enhanced the antitumor activity of docetaxel in a panel of prostate cancer models. An intermittent dosing schedule of lonafarnib coadministered with docetaxel may allow enhanced efficacy to that of continuous dosing by improving the tolerability of higher doses of lonafarnib.

Small molecule pan-bcl-2 inhibitor AT-101 induces apoptosis in NSCLC by up-regulating noxa and enhances antitumor activity of docetaxel or targeted kinase inhibitors

e14591 Background: AT-101 is an orally active pan Bcl-2 inhibitor currently under clinical development in Phase II trials. We investigated the effect of AT-101 alone or in combination with chemotherapies or targeted kinase inhibitors in NSCLC both in vitro and in vivo. Methods: Growth inhibition was measured by WST assays. The CalculSyn method was used to assess drug interaction by calculating the Combination Index (CI) value. The ability of AT-101 to potentiate the anti-cancer effect of chemotherapies or kinase inhibitors was evaluated in xenograft models. Results: A panel of 11 NSCLC cell lines with overexpression of Bcl-2, Bcl- XL or Mcl-1 proteins was treated with AT-101, docetaxel, pemetrexed, erlotinib, sorafenib, sunitinib, rapamycin, as a single agent and in combination. AT-101 inhibited the growth with IC50 at 3–9 uM. When treating cells simultaneously with both agents, AT-101 demonstrated strong synergy with those agents in A549 or H460 cells with CI values &lt; 1.0. Protein analysis results indicated that AT-101 caused apoptosis by a time- and dose-dependent induction of Noxa expression in those cells. The expression of Bcl- XL was not influenced by AT-101. Pro-Caspase-3 was reduced with increasing doses of AT-101. In vivo, combined treatment of AT-101 with docetaxel, erlotinib, or sorafenib synergistically suppressed subcutaneous NSCLC A549 cells tumor growth compared with treatment with either agent alone. The synergist effects with the ErbB1 inhibitor Erlotinib is associated with the overexpression of the target protein ErbB1 in those cells. Only combination therapy resulted in significant tumor growth delay and no significant toxicities were observed. Conclusions: Our results demonstrate that AT-101significantly enhances the anti-tumor activity of chemotherapy and targeted agents and may represent a promising new anticancer agent with a novel molecular mechanism. Molecular targeted therapy with AT-101 may improve the outcome of current chemotherapy for NSCLC with Bcl-2, Bcl-xL and/or Mcl-1 overexpression. [Table: see text]

The angiogenesis inhibitor NM-3 is active against human NSCLC xenografts alone and in combination with docetaxel

The novel isocoumarin 2-(8-hydroxy-6-methoxy-1-oxo-1 H-2-benzopyran-3-yl) propionic acid (NM-3) has completed phase I clinical evaluation as an orally bioavailable angiogenesis inhibitor. NM-3 directly kills both endothelial and tumor cells in vitro at low mM concentrations and is effective in the treatment of diverse human tumor xenografts in mice. The present work has assessed the activity of NM-3 against human non-small-cell lung cancer (NSCLC) cells when used alone and in combination with docetaxel. The results demonstrate that NM-3 decreases clonogenic survival of NSCLC cells at clinically achievable concentrations. The results also demonstrate that NM-3 is effective in the treatment of NSCLC (A549, NCI-H460) tumor xenografts in mice. Moreover, NM-3 potentiated the antitumor activity of docetaxel against NSCLC xenografts without increasing toxicity. Our findings indicate that NM-3 may be effective alone or in combination with docetaxel in the treatment of patients with NSCLC.

Down-Regulation of Intratumoral Aromatase Messenger RNA Levels by Docetaxel in Human Breast Cancers

The reason why chemotherapy induces resistance to subsequent hormonal therapy remains to be clarified in postmenopausal breast cancers. We hypothesized that chemotherapy might down-regulate the intratumoral biosynthesis of estrogens. Thus, we have studied the influence of chemotherapy (docetaxel) on intratumoral aromatase mRNA expression because aromatase is a key enzyme for intratumoral biosynthesis of estrogens. The mRNA levels of aromatase and its inducers [tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and cyclooxygenase 2 (COX-2)] were determined by a real-time polymerase chain reaction assay in breast cancer tissues obtained before and after neoadjuvant chemotherapy with docetaxel (four cycles of 60 mg/m2 every 3 weeks) in 16 postmenopausal patients with estrogen receptor (ER)- and/or progesterone receptor (PR)-positive breast cancers. ER and PR levels in tumor tissues were also determined by enzyme immunoassay before and after chemotherapy. The intratumoral aromatase mRNA levels decreased significantly (P < 0.05) after chemotherapy from 0.84 +/- 0.28 (mean +/- SE) to 0.47 +/- 0.28. The intratumoral TNF-alpha mRNA levels also decreased significantly (P < 0.05) after chemotherapy from 2.40 +/- 0.52 to 0.95 +/- 0.25. On the contrary, the intratumoral IL-6 and COX-2 mRNA levels showed a marginally significant increase (P = 0.07) and a significant increase (P < 0.05), respectively, after chemotherapy. PR levels showed a marginally significant decrease (P = 0.08) after chemotherapy, whereas ER levels were almost constant before and after chemotherapy. Antitumor activity of docetaxel is mediated, at least in part, through a down-regulation of aromatase expression in tumor tissues, resulting in the suppression of intratumoral estradiol synthesis. Aromatase expression seems to be regulated mostly by TNF-alpha, but not IL-6 and COX-2.

Antitumor activity of docetaxel.

The mechanism of action, cellular uptake, cytotoxicity, use in drug combinations, resistance profile, and toxicology of docetaxel are reviewed. Docetaxel acts by stabilizing microtubules--enhancing the rate and extent of tubulin polymerization, and inhibiting depolymerization. Docetaxel accumulates in tumor cells to a greater extent than paclitaxel and remains in the cells longer. This may explain why docetaxel is more cytotoxic and less schedule dependent than paclitaxel. Higher concentrations of paclitaxel than docetaxel are required to produce the same cytotoxic effect in many murine and human tumor cell lines. Docetaxel has shown cytotoxicity in 41% of tumor specimens, compared with 33% for paclitaxel. In vivo, docetaxel has substantial activity against a multitude of murine and human tumor models; in some cases, there was complete remission of advanced disease. Synergism occurs between docetaxel and cyclophosphamide, fluorouracil, vinorelbine, methotrexate, and etoposide. Cross-resistance to docetaxel does not necessarily occur in cell lines that are resistant to other antineoplastic agents. In animal toxicology studies, docetaxel principally affected tissues with a high cell trun-over, such as hematopoietic tissue. An intermittent-dose regimen is preferable to allow for resolution of hematopoietic effects. Preclinical study results suggest that docetaxel may be effective against various tumors, whether it is given alone or in combination with other antineoplastic drugs.