ABSTRACT
BACKGROUND: Guidelines from the National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Conference recommend a repeat fine-needle aspiration biopsy (FNAB) after 3 months for thyroid nodules with a nondiagnostic (ND) result. Our aims were to assess which factors influenced their clinical management and to determine if the timing of the repeat FNAB affects the diagnostic yield. METHODS: A retrospective institutional review of 298 patients from 1/2006 to 12/2007 with an ND FNAB was performed. The factors influencing the next step in management, including age, gender, history of radiation, presence of Hashimoto's thyroiditis, thyroid-stimulating hormone levels, and ultrasound characteristics, were evaluated. The effect of the time of the repeat FNABs on their diagnostic yield was assessed. RESULTS: Of the 298 patients in our cohort, 9% were referred directly for surgery, 76% had a repeat FNAB, and 15% were observed. Tumor size was the only independent variable correlated with treatment strategy after a ND FNAB. There was not a significant difference in diagnostic yields between repeat FNABs performed earlier than 3 months compared to those preformed later (p=0.58). CONCLUSION: The timing of repeat FNAB for an initial ND FNAB does not affect diagnostic yield of the repeat FNAB.
Subject(s)
Thyroid Gland/pathology , Thyroid Nodule/diagnosis , Thyroid Nodule/pathology , Aged , Biopsy, Fine-Needle , Cohort Studies , Female , Humans , Male , Middle Aged , Radiotherapy , Retrospective Studies , Thyroid Gland/diagnostic imaging , Thyroid Nodule/therapy , Thyroidectomy , Thyrotropin/blood , Time Factors , UltrasonographyABSTRACT
PURPOSE: Chk1 inhibitors, such as AZD7762, are in clinical development in combination with cytotoxic agents for the treatment of solid tumors, including pancreatic cancers. To maximize the likelihood of their clinical success, it is essential to optimize drug scheduling as well as pharmacodynamic biomarkers in preclinical models. EXPERIMENTAL DESIGN: We tested multiple schedules of administration of gemcitabine and AZD7762 on the survival of pancreatic cancer cells. Potential pharmacodynamic biomarkers including pChk1, pChk2, pHistone H3, and caspase-3 were evaluated in vitro, followed by assessment of promising candidate biomarkers in vivo. We then went on to determine the contributions of PP2A and DNA damage to the mechanism(s) of induction of the identified biomarker, pS345 Chk1. RESULTS: AZD7762 given during and after or after gemcitabine administration produced maximum chemosensitization. In vivo, AZD7762 significantly inhibited the growth of pancreatic tumor xenografts in response to gemcitabine. Of the biomarkers assessed, pS345 Chk1 was most consistently increased in response to gemcitabine and AZD7762 in tumors and normal tissues (hair follicles). pS345 Chk1 induction in response to gemcitabine and AZD7762 occurred in the presence of PP2A inhibition and in association with elevated γH2AX, suggesting that DNA damage is an underlying mechanism. CONCLUSIONS: AZD7762 sensitizes pancreatic cancer cells and tumors to gemcitabine in association with induction of pS345 Chk1. Together these data support the clinical investigation of AZD7762 with gemcitabine in pancreatic cancer under a dosing schedule in which gemcitabine is administered concurrent with or before AZD7762 and in conjunction with skin biopsies to measure pS345 Chk1.
Subject(s)
Deoxycytidine/analogs & derivatives , Protein Kinase Inhibitors/pharmacology , Protein Kinases/metabolism , Thiophenes/pharmacology , Urea/analogs & derivatives , Animals , Biomarkers/metabolism , Cell Line, Tumor , Cell Survival/drug effects , Checkpoint Kinase 1 , DNA Damage , Deoxycytidine/pharmacology , Histones/metabolism , Humans , Mice , Pancreatic Neoplasms/drug therapy , Phosphorylation/drug effects , Transplantation, Heterologous , Urea/pharmacology , Xenograft Model Antitumor Assays , GemcitabineABSTRACT
The median survival for patients with locally advanced pancreatic cancer treated with gemcitabine and radiation is approximately 1 year. To develop improved treatment, we have combined a Chk1/2-targeted agent, AZD7762, currently in phase I clinical trials, with gemcitabine and ionizing radiation in preclinical pancreatic tumor models. We found that in vitro AZD7762 alone or in combination with gemcitabine significantly sensitized MiaPaCa-2 cells to radiation. AZD7762 inhibited Chk1 autophosphorylation (S296 Chk1), stabilized Cdc25A, and increased ATR/ATM-mediated Chk1 phosphorylation (S345 Chk1). Radiosensitization by AZD7762 was associated with abrogation of the G(2) checkpoint as well as with inhibition of Rad51 focus formation, inhibition of homologous recombination repair, and persistent gamma-H2AX expression. AZD7762 was also a radiation sensitizer in multiple tumor xenograft models. In both MiaPaCa-2- and patient-derived xenografts, AZD7762 significantly prolonged the median time required for tumor volume doubling in response to gemcitabine and radiation. Together, our findings suggest that G(2) checkpoint abrogation and homologous recombination repair inhibition both contribute to sensitization by Chk1 inhibition. Furthermore, they support the clinical use of AZD7762 in combination with gemcitabine and radiation for patients with locally advanced pancreatic cancer.
Subject(s)
DNA Repair/drug effects , G2 Phase/drug effects , Pancreatic Neoplasms/radiotherapy , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Radiation-Sensitizing Agents/pharmacology , Thiophenes/pharmacology , Urea/analogs & derivatives , Adenocarcinoma/drug therapy , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Animals , Blotting, Western , Cell Line, Tumor , Checkpoint Kinase 1 , Checkpoint Kinase 2 , DNA Damage/drug effects , DNA Damage/radiation effects , DNA Repair/radiation effects , Deoxycytidine/analogs & derivatives , Deoxycytidine/pharmacology , Drug Therapy, Combination , Flow Cytometry , Fluorescent Antibody Technique , G2 Phase/radiation effects , Gamma Rays , Humans , Immunoblotting , Immunoenzyme Techniques , Mice , Mice, Inbred NOD , Mice, SCID , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/pathology , Protein Kinases/chemistry , Protein Kinases/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rad51 Recombinase/metabolism , Recombination, Genetic/drug effects , Recombination, Genetic/radiation effects , Reverse Transcriptase Polymerase Chain Reaction , Urea/pharmacology , Xenograft Model Antitumor Assays , GemcitabineABSTRACT
Clinical evidence suggests that gemcitabine (Gem) plus oxaliplatin (Ox) is superior to gemcitabine alone in advanced pancreatic carcinoma. The addition of radiation to gemcitabine improves response and is a standard treatment for locally advanced disease. We investigated the effect of oxaliplatin on gemcitabine-based chemoradiation by determining whether gemcitabine and oxaliplatin produced synergistic cytotoxicity using median effect analysis and radiosensitization using clonogenic survival assays. We analyzed the effects of gemcitabine and oxaliplatin on cell cycle distribution by DNA content and on radiation-induced DNA damage repair by phosphorylated H2AX (gamma-H2AX). Gemcitabine and oxaliplatin produced schedule-dependent synergistic cytotoxicity in BxPC-3 and Panc-1 cells (combination indices: 0.76 +/- 0.05, 0.61 +/- 0.11). In BxPC-3 cells, oxaliplatin did not affect gemcitabine-mediated radiosensitization (Gem 1.99 +/- 0.27; Gem + Ox 2.38 +/- 0.30). In Panc-1 cells, oxaliplatin significantly enhanced gemcitabine-mediated radiosensitization (Gem 1.31 +/- 0.05; Gem + Ox 2.90 +/- 0.31). Radiosensitization by gemcitabine was accompanied by early S-phase arrest and induction/persistence of gamma-H2AX protein, which were unaltered by oxaliplatin. Addition of oxaliplatin to gemcitabine produces radiosensitization equal to or greater than gemcitabine alone, supporting our clinical investigation of oxaliplatin with gemcitabine-radiation in pancreatic cancer aimed at improving systemic disease control while maintaining local tumor radiosensitization.
