Tumor Response Kinetics after Schedule-Dependent Paclitaxel Chemoradiation Treatment for Inoperable Non-small Cell Lung Cancer: A Model for Low-Dose Chemotherapy Radiosensitization
ABSTRACT Poor local disease control remains a major obstacle for inoperable non-small cell lung cancer (NSCLC) after radiotherapy. We previously reported results of a phase I/II clinical study based on preclinical investigations of paclitaxel radiation interactions for inoperable locally advanced NSCLC, which yielded remarkable local tumor responses and durable in-field tumor control using schedule-dependent low-dose paclitaxel for radiosensitization. Given our unique results, we analyzed the tumor response kinetics and conducted a statistical modeling of tumor response to characterize this regimen.
A total of 104 chest CT scans from 27 patients treated in the clinical trial were evaluated. Tumor volumes were calculated by three-dimensional measurements of pretreatment and serial post-therapy CT scans. A nonlinear mixed effects model was used to model response kinetics.
The average tumor volume reduction at 1 month post-therapy was 69.9 +/- 22.6% (standard deviation), and was 80.6 +/- 17.9% at the last follow-up. The nonlinear mixed effects model predicts that tumor volume will ultimately shrink by at least 75% for more than 75% of patients treated by this regimen. The model also suggests that maximum shrinkage is reached within 2 months after treatment.
Tumor volume response kinetics revealed a rapid shrinkage of gross tumors using schedule-dependent pulsed low-dose paclitaxel radiosensitization. This is contrary to the protracted tumor regression process observed in radiation alone or other chemoradiation combinations. Statistical modeling may prove useful in characterizing and comparing different therapeutic regimens.
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- "Understanding lung tumor volume changes during radiotherapy may one day help radiation oncologists optimize dose fractions and radiosensitizing strategies for individual patients. A small number of studies have described lung tumor volume changes during conventionally fractionated external beam radiotherapy     . Lung tumor changes during hypofractionated radiotherapy, especially when delivered in short courses (≤2 weeks), are less well understood. "
ABSTRACT: . To characterize the lung tumor volume response during conventional and hypofractionated radiotherapy (RT) based on diagnostic quality CT images prior to each treatment fraction. Methods . Out of 26 consecutive patients who had received CT-on-rails IGRT to the lung from 2004 to 2008, 18 were selected because they had lung lesions that could be easily distinguished. The time course of the tumor volume for each patient was individually analyzed using a computer program. Results . The model fits of group L (conventional fractionation) patients were very close to experimental data, with a median Δ% (average percent difference between data and fit) of 5.1% (range 3.5–10.2%). The fits obtained in group S (hypofractionation) patients were generally good, with a median Δ% of 7.2% (range 3.7–23.9%) for the best fitting model. Four types of tumor responses were observed—Type A: “high” kill and “slow” dying rate; Type B: “high” kill and “fast” dying rate; Type C: “low” kill and “slow” dying rate; and Type D: “low” kill and “fast” dying rate. Conclusions . The models used in this study performed well in fitting the available dataset. The models provided useful insights into the possible underlying mechanisms responsible for the RT tumor volume response.Computational and Mathematical Methods in Medicine 10/2013; 2013(1):637181. DOI:10.1155/2013/637181 · 0.77 Impact Factor
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ABSTRACT: Local and distant failure rates remain high despite aggressive chemoradiation (CRT) treatment for Stage III non-small-cell lung cancer. We conducted preclinical studies of docetaxel's cytotoxic and radiosensitizing effects on lung cancer cell lines and designed a pilot study to target distant micrometastasis upfront with one-cycle induction chemotherapy, followed by low-dose radiosensitizing docetaxel CRT. A preclinical study was conducted in human lung cancer cell lines NCI 520 and A549. Cells were treated with two concentrations of docetaxel for 3 h and then irradiated immediately or after a 24-h delay. A clonogenic survival assay was conducted and analyzed for cytotoxic effects vs. radiosensitizing effects of docetaxel. A pilot clinical study was designed based on preclinical study findings. Twenty-two patients were enrolled with a median follow-up of 4 years. Induction chemotherapy consisted of 75 mg/m(2) of docetaxel and 75 mg/m(2) of cisplatin on Day 1 and 150 mg/m(2) of recombinant human granulocyte colony-stimulating factor on Days 2 through 10. Concurrent CRT was started 3 to 6 weeks later with twice-weekly docetaxel at 10 to 12 mg/m(2) and daily delayed radiation in 1.8-Gy fractions to 64.5 Gy for gross disease. The preclinical study showed potent cytotoxic effects of docetaxel and subadditive radiosensitizing effects. Delaying radiation resulted in more cancer cell death. The pilot clinical study resulted in a median survival of 32.6 months for the entire cohort, with 3- and 5-year survival rates of 50% and 19%, respectively, and a distant metastasis-free survival rate of 61% for both 3 and 5 years. A pattern-of-failure analysis showed 75% chest failures and 36% all-distant failures. Therapy was well tolerated with Grade 3 esophagitis observed in 23% of patients. One-cycle full-dose docetaxel/cisplatin induction chemotherapy with recombinant human granulocyte colony-stimulating factor followed by pulsed low-dose docetaxel CRT is promising with regard to its antitumor activity, low rates of distant failure, and low toxicity, suggesting that this regimen deserves further investigation.International journal of radiation oncology, biology, physics 08/2011; 80(5):1358-64. DOI:10.1016/j.ijrobp.2010.04.060 · 4.26 Impact Factor
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ABSTRACT: The purpose of the proposed study is to evaluate the effectiveness and safety of low-dose paclitaxel with timed thoracic radiotherapy (TTR) for local control by inducing maximum radiosensitization through G2-M phase cell cycle arrest, followed by full dose adjuvant chemotherapy with gemcitabine and carboplatin for eradication of possible micrometastasis in unresectable stage III non-small cell lung cancer (NSCLC). This is a single-center, non-randomized prospective phase II study. Patients with unresectable stage III NSCLC were treated with paclitaxel 15mg/m(2) IV, followed by TTR 6h later on Monday/Wednesday/Friday, and TTR only on Tuesday/Thursday mornings (total 55Gy). Full dose adjuvant chemotherapy consisted of intravenous carboplatin (AUC 5) on day 1, gemcitabine 1000mg/m(2) on days 1 and 8, every 21 days for 4 cycles. The primary endpoint was overall survival (OS). Secondary endpoints were overall response rate (ORR), and toxicities. Twenty-seven patients were eligible for the study. Patient characteristics were: 19 males (70%); median age 67 years (range 39-82); 15 (56%) stage IIIB; 89% with ECOG performance status ≥1. Three-year OS was 16.7% in all patients, and 27.3% in patients received three or more cycles of adjuvant chemotherapy, respectively. ORR was 63%. Grade 3 toxicities during paclitaxel plus concurrent TTR phase were radiation esophagitis (11%) and radiation pneumonitis (4%), no grade 4 toxicities occurred. One grade 5 hemoptysis. Grade 3/4 toxicities during adjuvant gemcitabine/carboplatin were pneumonitis (22%), anemia (30%), neutropenia (22%), and thrombocytopenia (33%), one grade 5 neutropenic fever. Low-dose paclitaxel with concurrent TTR is an effective chemoradiotherapy regimen in unresectable stage III NSCLC. Improved survival benefit was observed in patients who have received three or more cycles of full dose adjuvant chemotherapy, yet, gemcitabine related radiation pneumonitis and hematological toxicities limited adjuvant chemotherapy delivery.Lung cancer (Amsterdam, Netherlands) 09/2013; 83(1). DOI:10.1016/j.lungcan.2013.09.007 · 3.96 Impact Factor