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Hak Choy

Publications and source records attributed to Hak Choy.

At least 19 recordsLinked to original sources
PubMed2006

Efficacy of ablative high-dose-per-fraction radiation for implanted human renal cell cancer in a nude mouse model.

OBJECTIVES: Stereotactic body radiation therapy (SBRT) is a new therapeutic paradigm that uses a very large dose per fraction treatments (ablative hypofractionation). We investigated the use of ablative hypofractionation in treating human renal cell carcinoma using a nude mouse model. METHODS: Nude mice were injected subcutaneously with A498 human renal carcinoma cells. Tumour-bearing animals were radiated with three fractions (one per week) for a total dose of 48 Gy (n = 12), while untreated animals served as controls (n = 7). The mice were weighed, and tumour volumes were measured at baseline and weekly until 7 weeks post-treatment. RESULTS: Control animals demonstrated progressive tumour growth and were sacrificed because of either tumour size or ulceration. Tumours in the treatment group grew to three times their initial size over the 3 weeks of treatment but subsequently decreased progressively to less than 30% of their initial volume. All treated tumours exhibited marked cytologic changes. Tumours from mice sacrificed before post-treatment week 4 had a mitotic count of 1-4/10 hpf. Tumours from mice sacrificed more than 4 weeks post-treatment (n = 4) demonstrated no mitoses. CONCLUSIONS: Treatment with high-dose-per-fraction radiation to 48 Gy resulted in a sustained decrease in tumour volume and marked cytologic changes. These results are preliminary--but promising--and encourage further research into this application of ablative hypofractionated radiation for kidney cancer.

Animals↗
PubMed2006

The cyclin-dependent kinase 2 inhibitor down-regulates interleukin-1beta-mediated induction of cyclooxygenase-2 expression in human lung carcinoma cells.

Overexpression of cyclooxygenase-2 (COX-2) is frequently observed in several human cancers, including lung, colon, and head and neck. Malignancies are also associated with the dysregulation of cell cycle events and concomitant elevated activity of cyclin-dependent kinases (CDK). CDK2 is a key cell cycle regulatory protein that controls the transition of cells from G(1) to S phase. In this study, we furnish several lines of evidence that show a functional role for the CDK2 in interleukin-1beta (IL-1beta)-induced COX-2 expression in H358 human non-small cell lung carcinoma cell line by blocking CDK2 activity. First, we show that BMS-387032, a potent CDK2 inhibitor, blocks IL-1beta-induced expression as well as steady-state mRNA levels of COX-2. Second, we show that small interfering RNA that abrogates CDK2 expression also blocks IL-1beta-induced COX-2 expression. Third, results from in vitro kinase assays clearly show that IL-1beta induces CDK2 activity in H358 cells and this activity is significantly inhibited by BMS-387032. Moreover, CDK2 inhibition blocks IL-1beta-induced binding to the NF-IL6 element of the COX-2 promoter and inhibits transcription of the COX-2 gene. We also observed that BMS-387032 does not inhibit endogenous expression of COX-2 or prostaglandin synthesis in lung carcinoma cells. Finally, we provide evidence showing that IL-1beta-induced signaling events, such as p38 mitogen-activated protein kinase, phosphorylated stress-activated protein kinase/c-Jun NH(2)-terminal kinase, phosphorylated AKT, and phosphorylated extracellular signal-regulated kinase 1/2, are not inhibited by CDK2 inhibitor. Taken together, the data suggest that CDK2 activity may play an important event in the IL-1beta-induced COX-2 expression and prostaglandin E(2) synthesis and might represent a novel target for BMS-387032.

CCAAT-Enhancer-Binding Proteins↗
PubMed2006

Efficacy of high dose per fraction radiation for implanted human prostate cancer in a nude mouse model.

PURPOSE: SBRT is a new therapeutic paradigm using large dose per fraction treatments (aggressive hypofractionation). While SBRT has shown efficacy for treating patients with lung, liver and spine tumors, to our knowledge there have been no preclinical studies evaluating the efficacy of this treatment for prostate cancer. We investigated the dose-response characteristics of SBRT for treating human prostate cancer in a nude mouse model. MATERIALS AND METHODS: Nude mice were injected subcutaneously into the right flank with C4-2 prostate cancer cells grown in culture. A dose escalation trial was performed to assess toxicity and response. Tumor bearing animals were radiated with 3 fractions (1 per week) for a total dose of 15 Gy in 11, 22.5 Gy in 9 and 45 Gy in 10, while 8 untreated animals served as controls. The mice were weighed, and tumor volume and PSA measurements were performed at baseline and weekly until 4 weeks after treatment. RESULTS: There was no treatment related toxicity. There was a significant difference in the tumor response to higher radiation doses. In the 15 and 22.5 Gy groups mean tumor volume decreased to 58% and 90% of the original volume, respectively, but the rats experienced progressive tumor regrowth within 1 week after the completion of therapy. The 45 Gy group had a mean tumor volume and PSA decrease of greater than 90%, which was sustained 1 month after treatment in all except 2 mice. CONCLUSIONS: SBRT dose level treatments were able to significantly decrease tumor volume and PSA. However, using 15 and 22.5 Gy durable responses were not achieved except in a few mice. The 45 Gy group demonstrated sustained PSA and tumor volume decreases in most mice. These results clearly show an increasing dose-response relationship for a range of hypofractionated dose levels, as used in SBRT.

Animals↗
PubMed2006

Satraplatin: an orally available platinum analog for the treatment of cancer.

Satraplatin is a novel, orally bioavailable, platinum anticancer drug. Platinum analogs form the mainstay of treatment for a number of cancers, including lung, ovarian, colorectal and head and neck cancer. A disadvantage of the currently marketed platinum analogs is that they must all be administered via intravenous infusion. In addition, their utility is often limited by toxicity, particularly neurotoxicity, ototoxicity and renal toxicity. Satraplatin has preclinical antitumor activity comparable with that of cisplatin and, clinically, has a more manageable side-effect profile. Satraplatin is active in lung, ovarian and prostate cancer, and appears to have good efficacy in combination with radiation for lung and head and neck cancer. Preclinical data suggest it may also be effective for the treatment of certain cisplatin-refractory tumors. A large, randomized Phase III trial is currently evaluating satraplatin in combination with prednisone for the treatment of patients with hormone-refractory prostate cancer whose disease has progressed following prior systemic therapy. Positive results from this trial would support regulatory approval for satraplatin for this indication. The availability of an active oral platinum agent, such as satraplatin, with few of the serious toxicities associated with traditional intravenous platinum compounds makes satraplatin an alternative to other platinum agents and a new treatment option in the oncologist's armamentarium.

Administration, Oral↗
PubMed2005

Response to combined modality therapy correlates with survival in locally advanced non-small-cell lung cancer.

PURPOSE: Although concurrent chemoradiotherapy can now achieve demonstrated long-term survival in patients with locally advanced non-small-cell lung cancer (LANSCLC), it is difficult to predict which patients will benefit most from this therapeutic approach. Studies have suggested that local control, and the response to therapy, may be linked to improved survival; however, detailed analysis of the impact of tumor response to chemoradiotherapy on survival has not been thoroughly reported. Therefore, we sought to determine the impact of the response rate on survival for patients who were treated with combined modality therapy for LANSCLC. METHODS AND MATERIALS: We reviewed the data from 116 patients enrolled between 1994 and 1997 in three trials investigating paclitaxel-based concurrent chemoradiotherapy for LANSCLC. Tumor size measurements were assessed immediately before and 2 months after completion of combined modality therapy to determine the response and to calculate the percentage of decrease in tumor size. RESULTS: Patients with a response (complete or partial) had an improved 4-year overall survival rate compared with patients with no response (stable or progressive disease; 21.1% vs. 3.3%, p <0.0001) in the 109 assessable patients. Progression-free survival also improved significantly with response. An analysis of the percentage of decrease in tumor size vs. survival was performed (n = 74) using Cox proportion model analysis. After combined modality therapy, a 20%, 40%, 60%, 80%, and 100% decrease in tumor size conferred a 39%, 63%, 78%, 86%, and 92% reduction in risk of death compared with a 0% decrease in tumor size (p <0.0001). CONCLUSION: The response by conventional response criteria correlated strongly with improved overall survival and progression-free survival and an increasing percentage of decrease in tumor size resulted in a reduction in the risk of death. Additional investigation of the degree of response as a factor predictive of improved therapeutic efficacy, translating into improved survival, is warranted.

Analysis of Variance↗
PubMed2005

Phase II multicenter study of induction chemotherapy followed by concurrent efaproxiral (RSR13) and thoracic radiotherapy for patients with locally advanced non-small-cell lung cancer.

PURPOSE: Efaproxiral (RSR13) reduces hemoglobin oxygen-binding affinity, facilitates oxygen release, and increases tissue pO2. We conducted a phase II multicenter study that assessed the efficacy and safety of efaproxiral when administered with thoracic radiation therapy (TRT), following induction chemotherapy, for treatment of locally advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Fifty-one patients with locally advanced NSCLC were enrolled at 13 sites. Treatment comprised two cycles of paclitaxel (225 mg/m2) and carboplatin (area under the curve, 6), 3 weeks apart, followed by TRT (64 Gy/32 fractions) with concurrent efaproxiral (50 to 100 mg/kg). Survival results were compared with results of study Radiation Therapy Oncology Group (RTOG) 94-10. RESULTS: Overall response rate was 75% (37 of 49 patients). Complete and partial response rates were 6% (three of 49 patients) and 69% (34 of 49 patients), respectively. Median survival time (MST) was 20.6 months (95% CI, 14.0 to 24.2); overall survival rates at 1- and 2-years were 67% and 37%, respectively. Survival results were compared with the sequential (S-CRT) and concurrent (C-CRT) chemoradiotherapy arms of RTOG 94-10. MSTs for cases matched by stage, Karnofsky performance status, and age were: RT-010, 20.6 months; S-CRT, 15.1 months; and C-CRT, 17.9 months. Grade 3 to 4 toxicities related to efaproxiral that occurred in more than one patient included transient hypoxemia (19%), radiation pneumonitis (11%), and fatigue (4%). CONCLUSION: Addition of efaproxiral to S-CRT represents a promising approach in NSCLC treatment, and a randomized study should be pursued. The low incidence of grade 3 to 4 toxicities suggests that the use of efaproxiral instead of a cytotoxic agent, as a radiation sensitizer, may be advantageous.

Adult↗
PubMed2005

Combined chemoradiotherapy regimens of paclitaxel and carboplatin for locally advanced non-small-cell lung cancer: a randomized phase II locally advanced multi-modality protocol.

PURPOSE: This phase II noncomparative randomized trial was conducted to determine the optimal sequencing and integration of paclitaxel/carboplatin with standard daily thoracic radiation therapy (TRT), in patients with locally advanced unresected stage III non-small-cell lung cancer (NSCLC). Survival data were compared with historical standard sequential chemoradiotherapy data from the Radiation Therapy Oncology Group. PATIENTS AND METHODS: Patients with unresected stages IIIA and IIIB NSCLC, with Karnofsky performance status > or = 70% and weight loss < or = 10%, received two cycles of induction paclitaxel (200 mg/m2)/carboplatin (area under the plasma concentration time curve [AUC] = 6) followed by TRT 63.0 Gy (arm 1, sequential) or two cycles of induction paclitaxel (200 mg/m2)/carboplatin (AUC = 6) followed by weekly paclitaxel (45 mg/m2)/carboplatin (AUC = 2) with concurrent TRT 63.0 Gy (arm 2, induction/concurrent), or weekly paclitaxel (45 mg/m2)/carboplatin (AUC = 2)/TRT (63.0 Gy) followed by two cycles of paclitaxel (200 mg/m2)/carboplatin (AUC = 6; arm 3, concurrent/consolidation). RESULTS: With a median follow-up time of 39.6 months, median overall survival was 13.0, 12.7, and 16.3 months for arms 1, 2, and 3, respectively. During induction chemotherapy, grade 3/4 granulocytopenia occurred in 32% and 38% of patients on study arms 1 and 2, respectively. The most common locoregional grade 3/4 toxicity during and after TRT was esophagitis, which was more pronounced with the administration of concurrent chemoradiotherapy on study arms 2 and 3 (19% and 28%, respectively). CONCLUSION: Concurrent weekly paclitaxel, carboplatin, and TRT followed by consolidation seems to be associated with the best outcome, although this schedule was associated with greater toxicity.

Aged↗
PubMed2005

Long term follow up and analysis of long term survivors in patients treated with paclitaxel-based concurrent chemo/radiation therapy for locally advanced non-small cell lung cancer.

PURPOSE: For patients with locally advanced non-small cell lung cancer (LANSCLC), concurrent chemotherapy/radiation therapy (RT) has become the standard of care. Three multi-institutional phase II studies with paclitaxel-based chemotherapeutic regimen given concurrently with RT for patients with LANSCLC were performed from March of 1994 to May of 1997. We sought to determine mature data from this database of patients, as well as to perform analysis of a cohort of patients who have achieved long term survival (LTS) when treated with this regimen. PATIENTS AND METHODS: Database of these patients was analyzed retrospectively upon longer follow up, with median follow up for the three studies being 498 days (range 11-2905 days, average 780 days). Weight loss limitation for the three studies was liberal: weight loss <10% and <15% 3 months preceding diagnosis (LUN-27 and LUN-63, respectively), and no weight loss limitation for LUN-56. RESULTS: The 4-year overall survival (OS) for the three trials was 16.3%, and 2-year progression free survival (PFS) was 25.7%. Statistical analysis of the long term survivors (OS > 4 years) was performed, and performance status (PS) was found to be a significant factor predictive of LTS. PS of 0 compared to 1 yielded a 2.5-fold increased likelihood of LTS (p = .04). There was also a trend (p = .067) for responders (complete or partial response) to yield a five-fold likelihood of LTS compared to non-responders (stable or progressive disease). CONCLUSION: Our results support the efficacy of combined modality therapy (CMT) for patients with LANSCLC even despite our more liberal weight loss eligibility criteria. Furthermore, our analysis indicates that LTS is more likely to be achievable in patients with PS = 0 compared to 1 when treated with CMT for LANSCLC.

Adult↗
PubMed2005

Phase I trial of Orzel (UFT plus leucovorin), cisplatin, and radiotherapy in the treatment of potentially resectable esophageal cancer.

PURPOSE: Fluorinated pyrimidines have been established as radiosensitizers in the combined modality therapy of esophageal cancer. UFT, an oral combination of a 5-fluorouracil pro-drug (uracil) and a dihydropyrimidine dehydrogenase inhibitor (ftorafur), may provide improvement in the ease of administration with equal efficacy. This Phase I study was designed to determine the maximal tolerated dose and dose-limiting toxicity of UFT, leucovorin, and cisplatin when given with radiotherapy in the neoadjuvant treatment of resectable esophageal cancer. METHODS: Chemotherapy consisted of i.v. cisplatin 80 mg/m(2) (Days 1 and 22) and UFT with leucovorin orally on Days 1-35. UFT was escalated in 50-mg/m(2) increments, starting at 200 mg/m(2)/d. Radiotherapy consisted of 4500 cGy in 25 fractions. Patients underwent resection 4-6 weeks after chemoradiotherapy. RESULTS: Ten patients with resectable esophageal cancer were enrolled. Of the 7 patients entered at dose level 1, 1 developed a dose-limiting toxicity of nausea. All 3 patients entered at dose level 2 developed dose-limiting toxicity. The maximal tolerated dose for UFT was the starting level, 200 mg/m(2)/d. Of the 10 patients enrolled, 8 underwent esophagectomy and 2 developed progressive disease and did not undergo surgery. The disease of 6 of the 8 patients was downstaged at surgery. CONCLUSION: The recommended UFT dose for Phase II studies is 200 mg/m(2)/d given orally in two divided doses when given with leucovorin, cisplatin, and radiotherapy.

Adenocarcinoma↗
PubMed2005

A phase I study of concurrent 9-nitro-20(s)-camptothecin (9NC/Orathecin) and radiation therapy in the treatment of locally advanced adenocarcinoma of the pancreas.

BACKGROUND AND PURPOSE: In vitro studies have suggested that 9-nitro-20(s)-Camptothecin (9NC/Orathecin/Rubitecan) can enhance the effects of radiation. We conducted a phase I study to assess the toxicity and determine the maximum tolerated dose of 9NC when combined with radiation in patients with locally advanced adenocarcinoma of the pancreas. PATIENTS AND METHODS: Eleven patients with locally advanced adenocarcinoma of the pancreas received 9NC, orally during radiation. Radiation therapy consisted of 45 Gy in 25 fractions given over 5 weeks. The starting dose of 9NC was 1 mg/m2/day. RESULTS: Eight patients received 9NC at a dose of 1 mg/m2/day and three patients received a dose of 1.25 mg/m2/day. Dose-limiting toxicity (DLT) was defined as >or=grade 3 non-hematologic toxicity and >or=grade 4 hematologic toxicity. Dose-limiting toxicity of grade 3 nausea/vomiting developed in one patient at the first dose level. At dose level 2, two of three patients developed DLT. Both developed grade 3 nausea, fatigue, and anorexia. Additionally, one of these patients had grade 3 dehydration and the other had grade 4 leukopenia, grade 3 vomiting, and grade 3 weakness. CONCLUSIONS: 9NC, 1 mg/m2/day, can be given concurrently with radiation with acceptable toxicity.

Adenocarcinoma↗
PubMed2005

Prophylactic cranial irradiation with combined modality therapy for patients with locally advanced non-small cell lung cancer.

Central nervous system (CNS) metastasis is a significant problem for many patients with non-small cell lung cancer (NSCLC). The earlier data reported a high incidence of CNS metastasis in patients with locally advanced NSCLC who were treated with radiotherapy alone. However, poor control of both thoracic and extracranial systemic disease dominated the results of the early trials. The risk for CNS metastasis as the first site of failure remains a significant concern for patients who have completed modern combined modality therapy. With improvements in the treatment of thoracic and systemic disease, there is renewed interest in prophylactic cranial irradiation (PCI). The results from the Radiation Therapy Oncology Group (RTOG) trial of PCI to prevent CNS relapse in patients with locally advanced NSCLC are anticipated.

Carcinoma, Non-Small-Cell Lung↗
PubMed2005

Induction paclitaxel/carboplatin followed by concurrent chemoradiation therapy for unresectable stage III non-small-cell lung cancer: a limited-access study--CALGB 9534.

BACKGROUND: This phase II cooperative group study of patients with unresectable stage III non-small-cell lung cancer was designed to treat patients with induction chemotherapy with paclitaxel and carboplatin (PC) followed by concurrent chemotherapy with the same chemotherapy plus thoracic irradiation to 66 Gy. PATIENTS AND METHODS: All enrolled patients were scheduled to receive 2 cycles of induction PC at conventional doses. All nonprogressing patients were subsequently treated with concurrent chemoradiation, including 7 weekly doses of PC and once-daily thoracic irradiation. The eligibility criteria allowed treatment of an expanded population of patients, unrestricted by previous weight loss. RESULTS: Despite the fact that 22% of patients had experienced > 5% weight loss in the preceding 6 months, 23 of the 40 eligible patients (58%) responded to the overall regimen. A 3-year failure-free survival rate of 15% and a 3-year overall survival rate of 27% were achieved. The 3-year overall survival rate is consistent with landmark cooperative group results for the combined modality treatment of a more highly selected patient population. CONCLUSION: The feasibility of this therapeutic approach in a cooperative group setting and inclusive of patients who were representative of the general population of stage III lung cancer patients was established.

Adult↗
PubMed2004

Dosimetric uncertainties of three-dimensional dose reconstruction from two-dimensional data in a multi-institutional study.

Inconsistencies in the treatment planning process leading to dosimetric uncertainties may affect conclusions drawn from interinstitutional radiation oncology clinical trials. The purpose of this study was to assess the dosimetric uncertainties resulting from the process of reconstructing three-dimensional dose distributions from two-dimensional treatment plan information provided by participating institutions in a randomized clinical trial. This study was based on American College of Radiology Protocol #427, Locally Advanced Multi-Modality Protocol; a multi-institutional phase II randomized study involving radiation therapy for patients with inoperable non-small cell lung cancer. Several sources of dosimetric uncertainty were identified and analyzed, including image quality of hard-copy computed tomography (CT) images, slice spacing of CT scans, treatment position, interpretations of target volumes by radiation oncologists, the contouring of normal anatomic structures, and the use of common beam models for all dose calculations. Each source of uncertainty was investigated using a set of plans, with the ideal characteristics of digital images with 3-mm axial slice spacing and a flat couch, consisting of eight cases from Vanderbilt University Medical Center with electronically transferred CT data. The target volume DVH values were dependent on the additional uncertainty introduced by differences in delineation of the target volumes by the participating radiation oncologists. The DVH values for the lungs and heart were dependent on image quality and treatment position. Esophagus DVH values were not dependent on any of the sources of uncertainty. None of the structure DVH values were dependent on slice thickness or variations in the contouring of normal anatomic structures. Reconstruction of three-dimensional dose distributions from two-dimensional treatment plan information may be useful in cases for which digital CT data is not available or for historical data review. However, dosimetric accuracy will depend on image quality of the treatment planning CT data and consistency in the delineation of tumor volumes.

Body Burden↗
PubMed2004

Broad spectrum receptor tyrosine kinase inhibitor, SU6668, sensitizes radiation via targeting survival pathway of vascular endothelium.

PURPOSE: Recent studies have demonstrated radiosensitization by inhibiting receptor tyrosine kinases (RTKs). Irradiation activates RTKs and their downstream prosurvival molecule, Akt. In this study, we investigated the mechanism by which SU6668, an inhibitor of RTKs involved in angiogenic pathways, enhances effects of irradiation. METHODS AND MATERIALS: Western blots were used to determine Akt phosphorylation. Clonogenic assays were performed to determine endothelial survival after combination of SU6668 and irradiation. This combination therapy was also tested in mouse models with Lewis lung carcinoma or glioblastoma multiforme (GL261) for inhibition of tumor growth and tumor vasculature by examining tumor volume, tumor vascular window, and blood flow. RESULTS: We found that SU6668 inhibited the Akt activation inducible by irradiation. Clonogenic survival of endothelial cells was decreased after the combined therapy compared with radiotherapy alone. In vivo studies demonstrated reduction of tumor vasculature and blood flow. In addition, 21 Gy in 7 fractions given concurrently with SU6668 resulted in tumor growth delay compared to either treatment alone. CONCLUSION: These data suggest that the combination therapy was more effective in destroying tumor vasculature than either treatment alone. SU6668 augments tumor-suppressive effects of radiotherapy in Lewis lung carcinoma and GL261 xenographs, possibly through reducing the survival of tumor endothelium.

Animals↗
PubMed2004

Introduction.

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Journal Article↗
PubMed2004

Potential role for epidermal growth factor receptor inhibitors in combined-modality therapy for non-small-cell lung cancer.

There has been a surge of interest in the translation of discoveries in molecular biology into clinically relevant therapies in the field of hematology/oncology. The epidermal growth factor receptor (EGFR) has been a molecular target of significant interest and investigation, and preclinical and clinical studies support a role for targeted therapy in a variety of cancers, including non-small-cell lung cancer (NSCLC) via compounds that specifically inhibit EGFR. ZD1839, IMC-C225, and OSI-774 are the most clinically developed of these compounds. Interestingly, preclinical studies have demonstrated that EGFR inhibitors may have radiation-sensitizing properties, as well as increased cytotoxic activity in combination with chemotherapeutic agents, suggesting a potential role for EGFR inhibitors as an adjunct to the current combined-modality approach for therapy of Stage III NSCLC. Therefore, clinical trials have been proposed and initiated to address the issue of determining the impact of the addition of EGFR inhibitors to the standard combined-modality regimen (chemotherapy/radiation therapy +/- surgery) for Stage III NSCLC. This article reviews preclinical and clinical data supporting the role for EGFR inhibitors alone or in combination with chemotherapy/radiation therapy for locally advanced NSCLC. Also, it will provide an overview of ongoing and proposed clinical studies investigating the potential role for EGFR inhibitors in Stage III NSCLC.

Antibodies, Monoclonal↗
PubMed2004

Enhancement of radiation effects by combined docetaxel and flavopiridol treatment in lung cancer cells.

BACKGROUND AND PURPOSE: To evaluate the potential role and mechanism of docetaxel plus flavopiridol in modulating radiosensitivity in vitro and in vivo. PATIENTS AND METHODS: In vitro. H460 human lung carcinoma cells were treated with docetaxel (10 nM for 1 h, at t = 0 h) --> radiation (0-5 Gy, at t = 6 h) --> flavopiridol (120 nM for 24 h, at t = 8 h). Colony forming ability was measured to assess the modulation of sensitivity. Cell cycle redistribution was measured by flow cytometric analysis using propidium iodide. Percent apoptosis was also measured by flow cytometric analysis using 7-amino-actinomycin D staining. In vivo. H460 cell xenografts were used in nude mice. Tumors were grown subcutaneously on the flank, then treated with docetaxel (2.5 mg/kg, at t = 0 h) --> radiation (2 Gy, at t = 6 h) --> flavopiridol (1.25 mg/kg, at t = 8 h) for 5 consecutive days. Tumor growth delay was then measured and compared with the control group. RESULTS: Docetaxel plus flavopiridol enhanced the effect of radiation. The maximum radiopotentiation and apoptosis were observed when the cells were treated with the sequence of docetaxel-->radiation-->flavopiridol both in vitro and in vivo. Flavopiridol and docetaxel induced G1 and G2/M arrest, respectively. CONCLUSIONS: This study shows that docetaxel plus flavopiridol enhances the effects of radiation in vitro and in vivo. Our data suggest that the mechanism of radiopotentiation by combining flavopiridol and docetaxel involves an enhancement of apoptosis and changes of cell cycle by docetaxel and flavopiridol.

Animals↗