Changhu Chen

Multi-institutional phase I/II trial of stereotactic body radiation therapy for lung metastases

PURPOSE To evaluate the efficacy and tolerability of high-dose stereotactic body radiation therapy (SBRT) for the treatment of patients with one to three lung metastases. PATIENTS AND METHODS Patients with one to three lung metastases with cumulative maximum tumor diameter smaller than 7 cm were enrolled and treated on a multi-institutional phase I/II clinical trial in which they received SBRT delivered in 3 fractions. In phase I, the total dose was safely escalated from 48 to 60 Gy. The phase II dose was 60 Gy. The primary end point was local control. Lesions with at least 6 months of radiographic follow-up were considered assessable for local control. Secondary end points included toxicity and survival. RESULTS Thirty-eight patients with 63 lesions were enrolled and treated at three participating institutions. Seventy-one percent had received at least one prior systemic regimen for metastatic disease and 34% had received at least two prior regimens (range, zero to five). Two patients had local recurrence after prior surgical resection. There was no grade 4 toxicity. The incidence of any grade 3 toxicity was 8% (three of 38). Symptomatic pneumonitis occurred in one patient (2.6%). Fifty lesions were assessable for local control. Median follow-up for assessable lesions was 15.4 months (range, 6 to 48 months). The median gross tumor volume was 4.2 mL (range, 0.2 to 52.3 mL). Actuarial local control at one and two years after SBRT was 100% and 96%, respectively. Local progression occurred in one patient, 13 months after SBRT. Median survival was 19 months. CONCLUSION This multi-institutional phase I/II trial demonstrates that high-dose SBRT is safe and effective for the treatment of patients with one to three lung metastases.

Regulation of glut1 mRNA by Hypoxia-inducible Factor-1 INTERACTION BETWEEN H-ras AND HYPOXIA

Oncogenic transformation and hypoxia both induceglut1 mRNA. We studied the interaction between theras oncogene and hypoxia in up-regulating glut1mRNA levels using Rat1 fibroblasts transformed with H-ras (Rat1-ras). Transformation with H-ras led to a substantial increase in glut1mRNA levels under normoxic conditions and additively increasedglut1 mRNA levels in concert with hypoxia. Using a luciferase reporter construct containing 6 kilobase pairs of theglut1 promoter, we showed that this effect was mediated at the transcriptional level. Promoter activity was much higher in Rat1-ras cells than in Rat1 cells and could be down-regulated by cotransfection with a dominant negative Ras construct (RasN17). A 480-base pair (bp) cobalt/hypoxia-responsive fragment of the promoter containing a HIF-1 binding site showed significantly higher activity in Rat1-ras cells than in Rat1 cells, suggesting that Ras might mediate its effect through HIF-1 even under normoxic conditions. Consistent with this, Rat1-ras cells displayed higher levels of HIF1-α protein under normoxic conditions. In addition, a promoter construct containing a 4-bp mutation in the HIF1 binding site showed lower activity in Rat1-ras cells than a construct with an intact HIF1 binding site. The activity of the latter construct but not the former could be down-regulated by RasN17, supporting the importance of the HIF1 binding site in regulation by Ras. The phosphatidylinositol 3-kinase inhibitor LY29004 down-regulated glut1 promoter activity and mRNA levels under normoxia and also decreased HIF1α protein levels in these cells. Collectively these results indicate that H-Ras up-regulates theglut1 promoter, at least in part, by increasing HIF-1α protein levels leading to transactivation of promoter through the HIF-1 binding site.

Poor prognosis in patients with stage I and II oral tongue squamous cell carcinoma

The objective of this study was to compare survival in patients with squamous cell carcinoma (SCC) of the oral tongue with that in patients with SCC in other oral cavity subsites.

Apoptosis in Heat-Induced Cell Killing: The Protective Role of hsp-70 and the Sensitization Effect of the c-myc Gene

We studied heat-induced apoptosis and loss of clonogenicity in Rat-1 fibroblasts, thermotolerant Rat-1 (TT Rat-1), Rat-1 transfected with the human hsp-70 gene (M21) and Rat-1 transfected with the human c-myc proto-oncogene (Rat-1:myc). Relative to Rat-1, TT Rat-1 and M21 cells are heat-resistant, but Rat-1:myc cells are heat-sensitive, in terms of both apoptosis and clonogenic survival. The apoptotic fractions assayed 24 h after a heat treatment of 60 min at 44 degrees C, are about 20% for Rat-1, 7% for TT Rat-1, 10% for M21 and 70% for Rat-1:myc cells, respectively. Most of the apoptotic cells detach from substratum within 1 day of heat treatment and exhibit morphological changes, chromatin condensation and DNA fragmentation. The results of this study suggest that (1) apoptosis is an important mechanism of heat-induced cell killing in some cell lines, (2) apoptosis-mediated cell killing manifests rapidly (relative to clonogenic assay) after a heat treatment, and (3) overexpression of the human hsp-70 gene reduces, whereas expression of the human c-myc proto-oncogene enhances, heat-induced apoptosis. Lastly, the effects of the hsp-70 and c-myc genes on the thermosensitivity of cells are correlated with their modulation of apoptosis.

Phase I Trial of Gefitinib in Combination With Radiation or Chemoradiation for Patients With Locally Advanced Squamous Cell Head and Neck Cancer

PURPOSE To establish the safety and toxicity profile of daily gefitinib with radiation alone or with concurrent chemoradiotherapy in previously untreated patients with locally advanced squamous cell head and neck cancer (LAHNC). PATIENTS AND METHODS Patients with intermediate-stage LAHNC were treated with concomitant boost radiation (RT) alone with escalating doses of daily gefitinib (250 or 500 mg; cohort I). Once a safety profile was determined with RT alone, patients with high-risk disease were then treated with daily gefitinib (250 or 500 mg), weekly cisplatin (CDDP; 30 mg/m2), and once-daily RT (cohort II). Patients also received post-RT gefitinib at 250 mg daily for a period of up to 2 years. RESULTS Twenty-three patients were enrolled and assessable for toxicity. No dose-limiting toxicities (DLTs) were observed in patients treated in cohort I at either 250 or 500 mg of gefitinib daily with concomitant boost RT to 72 Gy. In patients receiving chemoradiotherapy and gefitinib (cohort II), DLTs included one grade 4 diarrhea and one grade 4 neutropenic fever. Fifteen patients started maintenance gefitinib, and eight (53%) experienced grade 1 to 2 acne-like skin rash and diarrhea, but no grade 3 or 4 toxicity occurred. CONCLUSION Gefitinib (250 or 500 mg daily) was well tolerated with concomitant boost RT or concurrent chemoradiotherapy with weekly CDDP. Protracted administration of gefitinib for up to 2 years at 250 mg daily was also tolerated well.

Effect of Radiation Techniques in Treatment of Oropharynx Cancer

Objectives: To compare the toxicity and outcomes of three radiotherapy techniques—three‐dimensional conformal (3D‐RT), accelerated fractionation with concomitant boost (AFxCB), and intensity modulated radiotherapy (IMRT)—in the combined modality treatment of stage III–IV squamous cell carcinoma (SCC) of the oropharynx.

Apoptosis induced at different dose rates: implication for the shoulder region of cell survival curves

Apoptosis is induced by radiation, administered at different dose rates of 3-60 Gy/h, in rat embryo cells transfected with a c-myc oncogene (REC:myc(ch1)) or with a c-Ha-ras oncogene (REC:ras(ch1)). Apoptosis is evaluated in terms of altered morphology, chromatin condensation and DNA fragmentation. The apoptotic dose response of REC:myc(ch1) rises steeply at low doses (to about 40% at 5 Gy), and reaches a plateau at high doses (of about 60% at > 15 Gy). In comparison with REC:myc(ch1), the REC:ras(ch1) is much less susceptible, with a maximum apoptotic fraction of about 10%. Interestingly, radiation-induced apoptosis is nearly dose-rate independent. In parallel, we assessed radiation-induced cell-killing as assayed by colony-formation. In contrast to that observed for apoptosis, the dose response of colony-formation is strongly dependent on dose rate. Cell surviving fraction measured at 3 Gy/h decreases exponentially with dose, with REC:myc(ch1) exhibiting a steeper slope than REC:ras(ch1). Thus, the different low-dose-rate radiosensitivity of the two cell lines may in part be due to their different susceptibility to radiation-induced apoptosis. Taken together, these findings suggest that radiation-induced apoptosis contributes significantly to the initial (shoulder) region of acute dose-rate survival curves of susceptible cells, and may have implications for fractionated and low dose rate radiotherapy.

Survival and Patterns of Relapse in Patients With Oral Tongue Cancer

PURPOSE To evaluate the survival and patterns of relapse for patients with squamous cell carcinoma (SCC) of the oral tongue. PATIENTS AND METHODS Between 1999 and 2007, 50 patients with SCC of the oral tongue were treated at the University of Colorado Denver. Of the 50 patients, 38 had newly diagnosed SCC of the oral tongue (13 with stage I-II and 25 with stage III-IV disease), and 12 presented with locally recurrent SCC. Of the 50 patients, 49 were treated with initial surgery and 1 with definitive chemoradiotherapy. Adjuvant radiotherapy or chemoradiotherapy was administered to 42 patients after surgery. Of the 13 patients with newly diagnosed stage I-II disease, 7 did not receive adjuvant therapy. The actuarial locoregional control, freedom from distant relapse, and survival were determined using the Kaplan-Meier method, and comparisons were made using the log-rank test. RESULTS The median follow-up was 29 months (range 4 to 95) for living patients. The 2-year locoregional control and freedom from distant relapse rate was 58% and 83%, respectively. Locoregional control was particularly low among patients with stage I-II disease, for whom the 2-year locoregional control rate was only 35%. The median survival time and 2-year survival rate for all patients was 42 months and 65%, respectively. The 2-year survival rate for patients with stage I-II oral tongue cancer was 77% compared with 52% for patients with stage III-IV disease (P = .04). CONCLUSIONS Despite aggressive therapy, patients with SCC of the oral tongue have a low rate of local tumor control and survival, particularly among those with stage I-II disease. These patients should be considered for inclusion in clinical trials evaluating novel postoperative therapies.

Characterization of radiation-induced Apoptosis in rodent cell lines

For REC:myc(ch1), Rat1 and Rat1:myc(b) cells, we determined the events in the development of radiation-induced apoptosis to be in the following order: cell division followed by chromatin condensation, membrane blebbing, loss of adhesion and the uptake of vital dye. Experimental data which were obtained using 4He ions of well-defined energies and which compared the dependence of apoptosis and clonogenic survival on 4He range strongly suggested that in our cells both apoptosis and loss of clonogenic survival resulted from radiation damage to the cell nucleus. Corroboratory evidence was that BrdU incorporation sensitized these cells to radiation-induced apoptosis. Comparing the dose response for apoptosis and the clonogenic survival curves for Rat1 and Rat1:myc(b) cells, we concluded that radiation-induced apoptosis contributed to the overall radiation-induced cell inactivation as assayed by clonogenic survival, and that a modified linear-quadratic model, proposed previously, modeled such a contribution effectively. In the same context, the selective increase in radiation-induced apoptosis during late S and G2 phases reduced the relative radioresistance observed for clonogenic survival during late S and G2 phases.

Gefitinib plus cisplatin and radiotherapy in previously untreated head and neck squamous cell carcinoma: a phase II, randomized, double-blind, placebo-controlled study.

BACKGROUND AND PURPOSE To assess the efficacy and safety of gefitinib given concomitantly and/or as maintenance therapy to standard cisplatin/radiotherapy for previously untreated, unresected, stage III/IV non-metastatic SCCHN. MATERIALS AND METHODS In this phase II, double-blind, study, 226 patients were randomized to gefitinib 250mg/day, 500mg/day or placebo in two phases: a concomitant phase (gefitinib or placebo with chemoradiotherapy), followed by a maintenance phase (gefitinib or placebo alone). Primary endpoint was local disease control rate (LDCR) at 2years; secondary endpoints were LDCR at 1year, objective response rate, progression-free survival, overall survival, and safety and tolerability. RESULTS Gefitinib (250 and 500mg/day) did not improve 2-year LDCR compared with placebo either when given concomitantly with chemoradiotherapy (32.7% vs. 33.6%, respectively; OR 0.921, 95% CI 0.508, 1.670 [1-sided p=0.607]) or as maintenance therapy (28.8% vs. 37.4%, respectively; OR 0.684, 95% CI 0.377, 1.241 [1-sided p=0.894]). Secondary efficacy outcomes were broadly consistent with the 2-year LDCR results. In both doses, gefitinib was well-tolerated and did not adversely affect the safety and tolerability of concomitant chemoradiotherapy. CONCLUSION Gefitinib was well-tolerated, but did not improve efficacy compared with placebo when given concomitantly with chemoradiotherapy, or as maintenance therapy alone.