Randomized phase III, multicenter, open-label study comparing TH-302 in combination with doxorubicin versus doxorubicin alone in subjects with locally advanced unresectable or metastatic soft tissue sarcoma

TPS10100

Background: A hypoxic microenvironment characterizes solid tumors including soft tissue sarcoma (STS) and is associated with chemotherapy resistance. TH-302, a prodrug of the alkylating agent bromo-isophosphoramide mustard (BR-IPM) is reduced in hypoxic environments, releasing Br-IPM. Combining D with TH-302 should effectively target both the normoxic and hypoxic regions of STS. TH-302 was investigated with full-dose D (75 mg/m2). The regimen was well tolerated, >60% completed 6 cycles. DLTs at higher doses were infection with neutropenia and grade 4 thrombocytopenia. The efficacy was higher than generally reported with single agent D (Sleijfer, The Oncologist, 2005). At MTD (75 mg/m2 D and 300 mg/m2 TH-302) best response were 2 (2%) CR, 30 (34%) PR, 43 (48%) SD. Median PFS and OS were 6.7 and 17.5 months, respectively. Based upon these data, a study (NCT01440088) is ongoing to assess the benefit of adding TH-302 to the standard D as first-line therapy of STS. Methods: The randomized (1:1) phase III study of TH-302 (300 mg/m2) with D versus D alone was initiated September 2011. Target goal is 450 patients. TH-302 is administered IV over 30-60 minutes on Days 1 and 8 (21-day cycle). D (75 mg/m2, bolus or continuous) is administered Day 1 starting 2-4 hrs after TH-302 when used in combination. Patients receiving TH-302 plus D without progression after 6 cycles may continue on TH-302 alone. Key eligibility criteria: locally advanced unresectable or metastatic STS untreated with chemotherapy (adjuvant allowed), ECOG 0/1, measurable disease (RECIST 1.1) and adequate hematologic, hepatic, renal function. A FDA Special Protocol Agreement was reached on study design and analyses. Primary efficacy endpoint is overall survival (OS) comparison of the combination vs D. The study is designed to detect a 40% improvement in OS with 85% power and one-sided alpha of 2.5%. An interim futility PFS analysis is scheduled after 113 PFS events. Significant improvement in PFS (one-sided p < 0.10) is required to continue. A further analysis for early efficacy stoppage is scheduled after 175 OS events. IDMC will monitor safety and efficacy.

18f-FDG-PET imaging as an early survival predictor in patients with high-grade soft tissue sarcomas undergoing neoadjuvant therapy

10012

Background: Neoadjuvant therapy is associated with considerable toxicity and limited survival benefits in patients with soft tissue sarcoma (STS). We prospectively evaluated whether 18F-FDG PET/CT (PET) imaging after the initial cycle and after end of neoadjuvant therapy could predict overall survival in these patients. Methods: 76 patients (primary STS: n=57; metastatic disease: n=19) with high grade STS were included in this study. PET was performed prior to (n=76), after one cycle (n=52) and after the end of neoadjuvant therapy (n=74). Overall survival was correlated with changes of SUVpeak, RECIST, histopathological response and other parameters predictive of STS survival. Results: One-, two- and five- year survival rates were 95±3.0%, 86±4.6% and 68±6.6% for primary STS. Corresponding one- and two- year survival rates for recurrent/metastatic STS were 77±10.0% and 47±12.1%. Optimal cut-off for early decreases in SUV peak were significant predictors of survival in log-rank test (p=0.027 and p=0.043). However, late decreases in SUV peak were only predictive in primary STS (SUV peak decrease 57%; p=0.035) but not in recurrent/metastatic STS (SUV peak decrease 52%; p=0.057). In primary STS, 7/15 early PET non-responders but only 4/24 early PET responders died during follow up (p=0.068). Conclusions: 18F-FDG-PET seems feasible to predict survival after the initial cycle of neoadjuvant chemotherapy in both patients with primary STS and recurrent/metastatic STS and can potentially serve as an intermediate endpoint biomarker in clinical research and patient care.

Phase II trial of the CDK4 inhibitor PD0332991 in CDK4-amplified liposarcoma

10002

Background: CDK4 is amplified in approximately 90% of well-differentiated/de-differentiated liposarcomas (WD/DDLS). The selective CDK4/CDK6 inhibitor PD0332991 (PD) inhibits growth and induces senescence in liposarcoma cell lines and xenografts. In a phase I trial of PD, several patients with progressive WD/DDLS had prolonged stable disease for several years. To determine the safety and efficacy of PD, a phase II study was performed. Methods: Participants were patients with advanced WD/DDLS. Eligibility criteria were age≥18 years, measurable WD/DDLS (RECIST 1.1), documented progression on at least one systemic therapy directly before enrollment, CDK4 amplification by fluorescence in situ hybridization and retinoblastoma protein (RB) expression by immunohistochemistry (≥1+). Pts received oral PD 200mg daily for 14 consecutive days in 21-day cycles. The primary endpoint was progression-free survival (PFS) at 12 weeks. Based on historical data, a promising result was defined as a 12-week PFS of ≥40% and not promising as ≤20%. The sample size was up to 28 evaluable patients. If 9 patients were progression free at 12 weeks, then PD would be considered to have activity in WD/DDLS. Results: Of 44 patients screened (42/44 CDK4 amplified; 41/44 RB+), 29 were enrolled and 27 were evaluable for the primary endpoint. Median age was 65 (range 37-83); 52% were male; ECOG scores were 0 (69%) or 1 (31%), and the median number of prior regimens was 1 (range 1-5). PFS at 12 weeks was 70% (19/27 patients; 90% CI 56-100%), and thus the study significantly exceeded its primary endpoint. At the data cutoff, the median PFS was 18 weeks. Seven patients remain on study with stable disease at 18-48 weeks of followup. Grade 3 and 4 events included anemia (grade 3, 14%), thrombocytopenia (grade 3, 17%; grade 4, 14%), neutropenia (grade 3, 41%; grade 4, 7%) and febrile neutropenia (3%). Dose reductions were required in 24% of patients. Conclusions: Among patients with WD/DDLS with CDK4 amplification and RB expression who had actively progressing disease despite prior systemic therapy, treatment with the CDK4 inhibitor PD0332991 was associated with improved PFS. A randomized phase 3 trial is planned.

Randomized multicenter double-blind phase II trial: The immunological adjuvant OPT-821 with or without a trivalent ganglioside vaccine in metastatic sarcoma patients following metastasectomy

TPS10103

Background: The gangliosides GM2, GD2, and GD3 are strongly expressed in sarcoma and represent novel antitumor targets. We have demonstrated the safety and immunogenicity of individual monovalent ganglioside conjugate vaccines when administered with OPT821, a synthetic saponin adjuvant that augments the T-cell response. Antitumor effects are observed with anti-ganglioside antibodies in preclinical models, with greatest benefit seen in the micrometastatic setting. Patients (pts) with metastatic sarcoma rendered disease-free by surgery are at high risk for disease recurrence, with no therapy demonstrated to improve outcomes. Therefore, this population is ideally suited to test the efficacy of vaccine induced anti-ganglioside antibodies. We thus initiated this randomized double-blind phase II study of OPT821 with or without a trivalent ganglioside vaccine composed of GM2, GD2 lactone and GD3 lactone conjugated to KLH, an immunogenic carrier protein. Methods: A total of 134 pts will be randomized on a 1:1 basis stratified by disease state (relapsed disease vs metastasis at time of diagnosis), disease-free interval and number of relapses. Key inclusion criteria include stage IV sarcoma (locoregional recurrence is not sufficient) rendered disease-free following surgery or multi-modality therapy, no more than 8 weeks since surgery, and no continuous use of anti-inflammatory medications. Pts with Ewings sarcoma, GIST and rhabdomyosarcoma (except pleomorphic/anaplastic) are ineligible. Eligible pts will receive 10 subcutaneous injections in the outpatient setting over 84 weeks. The primary endpoint is progression-free survival (PFS). Secondary objectives include overall survival (OS) and 1- and 3-year PFS rate. Exploratory objectives include correlation of serologic response to outcome, comparison of tumor ganglioside expression at baseline and at recurrence, and analysis of circulating tumor cells. Enrollment began in July 2010. As of January 1, 2012, 83 patients had been recruited from 12 participating sites. Clinicaltrials.gov#: NCT01141491. Funded by Mabvax Therapeutics and NIH (R21CA13386).

A phase Ib/II study evaluating the efficacy of doxorubicin (D) with or without a human anti-PDGFRα monoclonal antibody olaratumab (IMC-3G3) in the treatment of advanced soft tissue sarcoma (STS)

TPS10099

Background: PDGFRα is a receptor commonly overexpressed in STS. Olaratumab is a fully human IgG1 MAb which specifically binds to human PDGFRα and blocks PDGFR-mediated signaling pathways. Olaratumab demonstrated significant tumor inhibition as a monotherapy and in combination with standard chemotherapy in preclinical human sarcoma xenograft models. A Phase 1b/2 clinical trial for patients with advanced or metastatic STS is currently enrolling patients in 9 sites across the United States; approximately 45 patients have been randomized. Methods: In Phase 1b, patients received olaratumab (15 mg/kg) via intravenous infusion on Days 1 and 8 of each 21-day cycle and D (75 mg/m²) 1 hour after olaratumab on Day 1. Phase 1b was completed without encountering dose-limiting toxicities; enrollment into Phase 2 has begun. The primary endpoint of the Phase 2 portion is to compare progression-free survival in patients with advanced STS when treated with D plus olaratumab versus D alone. Planned enrollment goal for Phase 2 is 130 patients. Patients are required to be ≥ 18 years old with ECOG 0-2, have appropriate organ function and histologically confirmed, measurable, and advanced STS. There is no restriction on the number of prior therapies. Patients are randomized 1:1 to either D plus olaratumab (Arm A) at same dose/schedule as in Phase 1b or D alone (Arm B). All patients can receive dexrazoxane. Upon completion of 8 cycles, patients in Arm A continue with olaratumab monotherapy. Patients in Arm B who develop disease progression during or after treatment can subsequently receive olaratumab monotherapy. Patients are stratified to treatment arms according to PDGFRα expression (positive vs. negative), number of previous lines of treatment, sarcoma subtype, and ECOG performance status. Response assessment occurs every 6 weeks. Exploratory analyses include biomarkers of olaratumab pharmacodynamic activity including PDGF ligands, PDGFR downstream molecules, VEGF, and changes in vascularity of tumor specimens.

A first-in-human, phase Ib combination study to assess safety, pharmacokinetics (PK), and pharmacodynamics (PD) of a hedgehog inhibitor, GDC-0449, with a Notch inhibitor, RO4929097, in patients with advanced sarcoma

10004

Background: Aberrant Hedgehog and Notch signaling is seen in sarcoma and anti-tumor activity is enhanced by inhibiting both pathways. This first in man Phase Ib study evaluated safety and efficacy of the combination of GDC-0449 (G), a smoothened inhibitor with RO4929097 (R), a gamma-secretase/notch inhibitor. Methods: The study evaluated fixed dose G (150 mg qd) for 21 days followed by G + R at either 10 mg (level 1) or 15 mg (level 2) QD. At MTD pts were evaluated with G + R (without “lead in” G) or single agent R. Pre and post treatment tumor biopsies were obtained to assess notch and hedgehog inhibition. PK was assessed for each drug. Key eligibility: advanced sarcoma, ECOG ≤ 2, age ≥ 18 and prior therapies ≤ 4. RECIST response was assessed Q6 wks. Results: 34 pts had a median age of 53 yrs (23-78), median priors 3 and various histologies [liposarcoma (7), chondrosarcoma (7), leiomyosarcoma (4), osteosarcoma (2), GIST (2) and other (12)]. No DLT was seen. Common (≥10 %) grade ≤3 toxicity was hypophosphatemia (18%). Systemic exposure (AUC0-24 and Cmax) of G was similar to established studies (not shown). AUC0-24 and Cmax of R was significantly lower (~70%) when administered with G (Table). However, measurement of unbound, free drug (Cfree) of R showed comparable levels between single agent R and G + R, but not when G was a “lead in” (Table). Target inhibition of the notch pathway (cleaved notch) and pAkt was observed in matched tumor biopsies with both arms. Durable SD was seen in both arms: myxoid chondrosarcoma (56 wks), liposarcoma (24+ wks), clear cell (21+ wks), desmoid (17+ wks), spindle cell (15+ wks) and chondrosarcoma (13+ wks). Conclusions: The combination of G+R is well tolerated and the RP2D is G 150 mg qd and R 15 mg qd without a “lead in” G. Despite reduction in total levels of R in the combination, free drug was similar and inhibits target. Disease stability was seen with R and R + G. Further clinical development of notch and hedgehog inhibitors in sarcomas is warranted. [Table: see text]

Phase II study of ganitumab, a fully human anti-type-1 insulin-like growth factor receptor antibody, in patients with metastatic Ewing family tumors or desmoplastic small round cell tumors

PURPOSE

Ganitumab is a fully human monoclonal antibody against type-1 insulin-like growth factor receptor (IGF1R). An open-label phase II study was conducted to evaluate the efficacy and safety of ganitumab monotherapy in patients with metastatic Ewing family tumors (EFT) or desmoplastic small round cell tumors (DSRCT).

PATIENTS AND METHODS

Patients ≥16 years of age with relapsed or refractory EFT or DSRCT received 12 mg/kg of ganitumab every 2 weeks. Objective response rate (ORR) was the primary end point. Secondary end points included clinical benefit rate (CBR = complete + partial responses + stable disease [SD] ≥ 24 weeks) and safety and pharmacokinetic profiles of ganitumab. The relationship between tumor response and EWS gene translocation status and IGF-1 levels was evaluated.

RESULTS

Thirty-eight patients (22 with EFT; 16 with DSRCT) received one or more doses of ganitumab. Twenty-four patients (63%) experienced ganitumab-related adverse events. Grade 3 related events included hyperglycemia (n = 2), thrombocytopenia (n = 5), neutropenia (n = 2), leukopenia (n = 1), and transient ischemic attack (n = 1). There were no grade 4 or 5 treatment-related events. Of 35 patients assessed for response, two had partial responses (ORR, 6%) and 17 (49%) had SD. Four patients had SD ≥ 24 weeks, contributing to a CBR of 17%. The pharmacokinetic profile of ganitumab was similar to that observed in the first-in-human trial. Elevation of IGF-1 levels was observed postdose. EWS-Fli1 translocations were analyzed by RNA sequencing and fluorescent in situ hybridization, and novel translocations were observed in EFT and DSCRT. No apparent relationship between tumor response and IGF-1 levels or EWS gene translocations was observed.

CONCLUSION

Ganitumab was well tolerated and demonstrated antitumor activity in patients with advanced recurrent EFT or DSRCT.

Abstract 4570: Functional analysis of gene expression profiling of primary and metastatic melanoma: Possible implications from BRAF mutant and wild-type cell lines

Metastatic melanoma is largely refractory to existing therapies and has a very poor prognosis. Despite the recent development of new therapies, the median survival rate is only 6-9 months and 5-year survival is less than 5%. Better understanding of melanoma biology, specifically the gene expression profile between primary and metastatic melanoma, may provide useful information for developing new therapeutic approaches to this disease. The gene expression profile from 89 primary and metastatic melanoma tissues was investigated by cDNA microarray. 8261 differentially expressed genes were identified between primary and metastatic melanoma at a statistical level p &lt;0.01 and false discovery rate (FDR) of 5%. Panther Pathway Classification showed that the 8261 differentially expressed genes were enriched with genes which were involved in cytoskeletal regulation by Rho GTPase, inflammation mediated by chemokine and cytokine signaling pathways, Notch signalling pathways, p53 and angiogenesis pathways. The primary melanoma microarrays were analyzed according to the thickness of tumour. Group A: the thickness of a tumour less than 2.0 mm, 20 microarrays. Group B: the thickness of a tumour was equal or more than 2.0 mm, 11 microarrays. 981 genes were identified as differentially expressed between Group A and Group B at statistical level p&lt;0.01 and FDR=5%. 657 out of 981 differentially expressed genes were shared with the 8261 differentially expressed genes. We believed these 657 genes were related to malignant potential of melanoma; they were enriched with genes which were involved in apoptosis, cell adhesion, cell cycle regulation and immune system processing. 218 out of the 657 genes overlapped with a published gene list (308 genes) which have been implicated in melanoma metastases. We further evaluated the expression of the transcription factor gene: ETV1. Ets variant 1 (ETV1) gene expression was significantly increased in metastatic melanoma and in primary melanoma with tumour thickness equal or more than 2.0 mm. We investigated the ETV1 expression in human melanoma cell lines. ETV1 mRNA level in 7 BRAF inhibitor sensitive cell lines was significantly lower than that in 6 BRAF inhibitor resistant cell lines (0.230±0.057 vs 0.927±0.6, p&lt;0.0001). The ETV1 expression in BRAF-induced resistant melanoma cell lines was significantly (p&lt;0.05) higher than in their parental cell lines. While a variety of genes are differentially expressed in primary and metastatic melanoma, the transcription factor–ETV1 gene may be an important target for study and as a therapeutic target as its expression may be associated with BRAF inhibitor resistance in melanoma 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 4570. doi:1538-7445.AM2012-4570

18F-FDG-PET/CT Imaging as an early survival predictor in patients with primary high-grade soft tissue sarcomas undergoing neoadjuvant therapy

PURPOSE

Neoadjuvant therapy is associated with considerable toxicity and limited survival benefits in patients with soft tissue sarcoma (STS). We prospectively evaluated whether 2[18F]fluoro-2-deoxy-d-glucose ((18)F-FDG)-PET/computed tomographic (CT) imaging after the initial cycle of neoadjuvant therapy could predict overall survival in these patients.

EXPERIMENTAL DESIGN

Thirty-nine patients underwent (18)F-FDG-PET/CT before and after one cycle of neoadjuvant therapy. Fifty-six patients underwent end-of-treatment PET. Overall survival was, among others, correlated with changes of SUV(peak) and histopathology.

RESULTS

One-, two-, and five-year survival rates were 95% ± 3.0%, 86% ± 4.6%, and 68% ± 6.6%, respectively. Median time to death was 30.9 months (mean, 27.7; range, 6.9-50.1). Optimal cutoff values for early and late decreases in SUV(peak) (26% and 57%, respectively) were significant predictors of survival in univariate survival analysis [P = 0.041; HR, 0.27; 95% confidence interval (CI), 0.08-0.95 and P = 0.045; HR, 0.31; 95% CI, 0.10-0.98]. Seven of 15 early PET nonresponders but only four of 24 early PET responders died during follow-up (P = 0.068). The only other significant survival predictor was surgical margin positivity (P = 0.041; HR, 3.31; 95% CI, 1.05-10.42). By multivariable analysis, early metabolic response (P = 0.016) and positivity of surgical margins (P = 0.036) remained significant survival predictors.

CONCLUSION

(18)F-FDG-PET predicted survival after the initial cycle of neoadjuvant chemotherapy in patients with STS and can potentially serve as an intermediate endpoint biomarker in clinical research and patient care.

Clinical cancer advances 2011: Annual Report on Progress Against Cancer from the American Society of Clinical Oncology

A message from ASCO'S President. It has been forty years since President Richard Nixon signed the National Cancer Act of 1971, which many view as the nation's declaration of the "War on Cancer." The bill has led to major investments in cancer research and significant increases in cancer survival. Today, two-thirds of patients survive at least five years after being diagnosed with cancer compared with just half of all diagnosed patients surviving five years after diagnosis in 1975. The research advances detailed in this year's Clinical Cancer Advances demonstrate that improvements in cancer screening, treatment, and prevention save and improve lives. But although much progress has been made, cancer remains one of the world's most serious health problems. In the United States, the disease is expected to become the nation's leading cause of death in the years ahead as our population ages. I believe we can accelerate the pace of progress, provided that everyone involved in cancer care works together to achieve this goal. It is this viewpoint that has shaped the theme for my presidential term: Collaborating to Conquer Cancer. In practice, this means that physicians and researchers must learn from every patient's experience, ensure greater collaboration between members of a patient's medical team, and involve more patients in the search for cures through clinical trials. Cancer advocates, insurers, and government agencies also have important roles to play. Today, we have an incredible opportunity to improve the quality of cancer care by drawing lessons from the real-world experiences of patients. The American Society of Clinical Oncology (ASCO) is taking the lead in this area, in part through innovative use of health information technology. In addition to our existing quality initiatives, ASCO is working with partners to develop a comprehensive rapid-learning system for cancer care. When complete, this system will provide physicians with personalized, real-time information that can inform the care of every patient with cancer as well as connect patients with their entire medical teams. The rapid learning system will form a continuous cycle of learning: securely capturing data from every patient at the point of care, drawing on evidence-based guidelines, and evaluating quality of care against those standards and the outcomes of other patients. Clinical trials are another area in which collaboration is critical. Increasing clinical trial participation will require commitment across the cancer community from physicians, patients, insurers, hospitals, and industry. A 2010 report by the Institute of Medicine described challenges to participation in trials by both physicians and patients and provided recommendations for revitalizing clinical trials conducted through the National Cancer Institute's Cooperative Group Program. ASCO has pledged its support for the full implementation of these recommendations. More broadly, ASCO recently outlined a bold vision for translational and clinical cancer research for the next decade and made recommendations to achieve that vision. Accelerating Progress Against Cancer: ASCO's Blueprint for Transforming Clinical and Translational Research, released in November, calls for a research system that takes full advantage of today's scientific and technologic opportunities and sets a high-level agenda for policy makers, regulators, and advocates. Cancer research has transformed cancer care in the past forty years, and this year's Clinical Cancer Advances illustrates how far we have come in the past year alone. We now have a tremendous opportunity to use today's knowledge and collaborate across all facets of cancer care to conquer this deadly disease. Michael P. Link, MD President American Society of Clinical Oncology.

3'-deoxy-3'-[18F]fluorothymidine positron emission tomography for response assessment in soft tissue sarcoma: a pilot study to correlate imaging findings with tissue thymidine kinase 1 and Ki-67 activity and histopathologic response

BACKGROUND

This study sought to determine whether [(18)F]fluorothymidine (FLT) positron emission tomography (PET)/computed tomography (CT) imaging allows assessment of tumor viability and proliferation in patients with soft tissue sarcomas who are treated with neoadjuvant therapy.

METHODS

Twenty patients with biopsy-proven, resectable, high-grade soft tissue sarcoma underwent [(18)F]FLT PET/CT imaging before and after neoadjuvant therapy. Histologic subtypes included sarcomas not otherwise specified (n = 5), malignant peripheral nerve sheath tumors (n = 3), gastrointestinal stromal tumors (n = 3), leiomyosarcomas (n = 3), angiosarcomas (n = 2), and others (n = 4). Changes in [(18)F]FLT peak standardized uptake value (SUVpeak) were correlated with percent necrosis in excised tissue, whereas posttreatment [(18)F]FLT tumor uptake was correlated with thymidine kinase 1 (TK1) expression and Ki-67 staining indices in excised tumor tissue.

RESULTS

Tumor FLT SUVpeak averaged 7.1 ± 3.7 g/mL (range, 1.9-16.1 g/mL) at baseline and decreased significantly to 2.7 ± 1.6 g/mL (range, 0.8-6.0 g/mL) at follow-up (P < .001); however, marked reductions in SUV were not specific for histopathological response. The posttreatment SUVpeak did not correlate with TK1 (P = .27) or Ki-67 expression (P = .21).

CONCLUSIONS

Marked reductions in [(18)F]FLT tumor uptake in response to neoadjuvant treatment were observed in most patients with sarcoma. However, these reductions were not specific for histopathologic response to neoadjuvant therapy. Furthermore, posttreatment [(18)F]FLT tumor uptake was unrelated to tumor proliferation by Ki-67 and TK1 staining. These results question the value of [(18)F]FLT PET imaging for treatment response assessments in patients with soft tissue sarcoma.

Correlation between glycolytic phenotype and tumor grade in soft-tissue sarcomas by 18F-FDG PET

Tumor glycolytic phenotyping can be accomplished with (18)F-FDG PET. Tumor (18)F-FDG uptake correlates with tumor grade in several cancers. However, the role of (18)F-FDG PET for the grading of soft-tissue sarcomas (STSs) warrants further research.

METHODS

One hundred two patients (48 men and 54 women; mean age +/- SD, 50 +/- 17 y) with 12 STS subtypes underwent (18)F-FDG PET/CT before treatment. Tumor (18)F-FDG uptake, expressed as maximum standardized uptake value (SUVmax), was compared among subtypes and correlated with histopathologic grade. Two frequently used sarcoma grading systems--the 3-tier system of the French Federation of Cancer Centers Sarcoma Group (Fédération Nationale des Centres de Lutte Contre le Cancer [FNCLCC]) and a 2-tier system (low grade vs. high grade)--were used.

RESULTS

More than 90% of STSs (93/102) exhibited a strong glycolytic phenotype (SUVmax, 2.7-52.2 g/mL). Tumor SUVmax differed significantly among tumor grades (P < 0.001 for the 3- and 2-tier grading systems). The FNCLCC and 2-tier grading systems predicted tumor grade with similar accuracy (area under the curve, 0.83 and 0.85, respectively; P = 0.35). SUVmax differed significantly among histologic subtypes (P = 0.03) in the entire population but not when high-grade STSs were analyzed separately (P = 0.31).

CONCLUSION

The tumor glycolytic phenotype correlated significantly with histologic grade as determined by both the FNCLCC and 2-tier (high vs. low) grading systems. (18)F-FDG PET cannot be used to reliably distinguish among grade 2 and 3 STSs (by FNCLCC) and the various subtypes.

Quantitative F18-fluorodeoxyglucose positron emission tomography accurately characterizes peripheral nerve sheath tumors as malignant or benign

BACKGROUND

Correct pretreatment classification is critical for optimizing diagnosis and treatment of patients with peripheral nerve sheath tumors (PNSTs). The aim of this study was to evaluate whether F18-fluorodeoxyglucose positron emission tomography (FDG PET) can differentiate malignant (MPNST) from benign PNSTs.

METHODS

Thirty-four adult patients presenting with PNST who underwent a presurgical FDG PET/computed tomography (CT) scan between February 2005 and November 2008 were included in the study. Tumors were characterized histologically, by FDG maximum standardized uptake value (SUV(max) [g/mL]), and by CT size (tumor maximal diameter [cm]). The accuracy of FDG PET for differentiating MPNSTs from benign PNSTs (neurofibroma and schwannoma) was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

SUV(max) was measured in 34 patients with 40 tumors (MPNSTs: n = 17; neurofibromas: n = 9; schwannomas: n = 14). SUV(max) was significantly higher in MPNST compared with benign PNST (12.0 +/- 7.1 vs 3.4 +/- 1.8; P < .001). An SUV(max) cutoff point of > or =6.1 separated MPNSTs from BPSNTs with a sensitivity of 94% and a specificity of 91% (P < .001). By ROC curve analysis, SUV(max) reliably differentiated between benign and malignant PNSTs (area under the ROC curve of 0.97). Interestingly, the difference between MPNSTs and schwannomas was less prominent than that between MPNSTs and neurofibromas.

CONCLUSIONS

Quantitative FDG PET imaging distinguished between MPNSTs and neurofibromas with high accuracy. In contrast, MPNSTs and schwannomas were less reliably distinguished. Given the difficulties in clinically evaluating PNST and in distinguishing benign PNST from MPNST, FDG PET imaging should be used for diagnostic intervention planning and for optimizing treatment strategies.

FDG-PET/CT imaging predicts histopathologic treatment responses after the initial cycle of neoadjuvant chemotherapy in high-grade soft-tissue sarcomas

PURPOSE

In patients with soft-tissue sarcoma (STS), the early assessment of treatment responses is important. Using positron emission tomography/computed tomography (PET/CT) with [(18)F]fluorodeoxyglucose (FDG), we determined whether changes in tumor FDG uptake predict histopathologic treatment responses in high-grade STS after the initial cycle of neoadjuvant chemotherapy.

EXPERIMENTAL DESIGN

From February 2006 to March 2008, 50 patients with resectable high-grade STS scheduled for neoadjuvant therapy and subsequent tumor resection were enrolled prospectively. FDG-PET/CT before (baseline), after the first cycle (early follow-up), and after completion of neoadjuvant therapy (late follow-up) was done. Tumor FDG uptake and changes were measured by standardized uptake values. Histopathologic examination of the resected specimen provided an assessment of treatment response. Patients with > or = 95% pathologic necrosis were classified as treatment responders. FDG-PET/CT results were compared with histopathologic findings.

RESULTS

At early follow-up, FDG uptake decreased significantly more in 8 (16%) responders than in the 42 (84%) nonresponders (-55% versus -23%; P = 0.002). All responders and 14 of 42 nonresponders had a > or = 35% reduction in standardized uptake value between baseline and early follow-up. Using a > or = 35% reduction in FDG uptake as early metabolic response threshold resulted in a sensitivity and specificity of FDG-PET for histopathologic response of 100% and 67%, respectively. Applying a higher threshold at late follow-up improved specificity but not sensitivity. CT had no value at response prediction.

CONCLUSION

A 35% reduction in tumor FDG uptake at early follow-up is a sensitive predictor of histopathologic tumor response. Early treatment decisions such as discontinuation of chemotherapy in nonresponding patients could be based on FDG-PET criteria.

The multidisciplinary management of osteosarcoma

Patients with suspected or confirmed osteosarcoma should be evaluated and treated at a comprehensive cancer center within a multidisciplinary sarcoma program that includes pediatric, medical and radiation oncologists, orthopedic and surgical oncologists, musculoskeletal pathologists, and radiologists. Successful treatment involves proper diagnosis, neoadjuvant and adjuvant multi-agent chemotherapy, and aggressive surgery with an emphasis toward limb-preserving procedures. Treatment of osteosarcoma should be undertaken within the framework of large cooperative group clinical trials for children, adolescents, and adults. Patients treated with osteosarcoma should be followed closely both for recurrence of disease and for development of late effects of the treatment of their cancer. The treatment of metastatic, recurrent and/or refractory disease is more controversial. Despite advances in systemic treatment, surgical technique, and supportive care, the overall outcome is still poor.

Reduction of glucose metabolic activity is more accurate than change in size at predicting histopathologic response to neoadjuvant therapy in high-grade soft-tissue sarcomas

PURPOSE

Change in tumor size as classified by Response Evaluation Criteria in Solid Tumors poorly correlates with histopathologic response to neoadjuvant therapy in patients with soft-tissue sarcomas. The aim of this study was to prospectively evaluate whether positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) allows for a more accurate evaluation of histopathologic response.

EXPERIMENTAL DESIGN

From January 2005 to January 2007, 42 patients with resectable biopsy-proven high-grade soft-tissue sarcoma underwent a FDG-PET/computed tomography scan before and after neoadjuvant treatment. Relative changes in tumor FDG uptake and size from the baseline to the follow-up scan were calculated, and their accuracy for assessment of histopathologic response was compared by receiver operating characteristic curve analysis. Histopathologic response was defined as > or =95% tumor necrosis.

RESULTS

In histopathologic responders (n = 8; 19%), reduction in tumor FDG uptake was significantly greater than in nonresponders (P < 0.001), whereas no significant differences were found for tumor size (P = 0.24). The area under the receiver operating characteristic curve for metabolic changes was 0.93, but only 0.60 for size changes (P = 0.004). Using a 60% decrease in tumor FDG uptake as a threshold resulted in a sensitivity of 100% and a specificity of 71% for assessment of histopathologic response, whereas Response Evaluation Criteria in Solid Tumors showed a sensitivity of 25% and a specificity of 100%.

CONCLUSION

Quantitative FDG-PET was significantly more accurate than size-based criteria at assessing histopathologic response to neoadjuvant therapy. FDG-PET should be considered as a modality to monitor treatment response in patients with high-grade soft-tissue sarcoma.

Advances in chemotherapy for patients with extremity soft tissue sarcoma

Doxorubicin-based chemotherapy does not appear to offer a survival benefit to patients who have high-risk primary extremity soft tissue sarcomas, whereas ifosfamide-based chemotherapy does. This benefit is likely histology- and size-specific. Until a less toxic targeted systemic therapy is developed, treatment with ifosfamide should be strongly considered in patients who have high-risk primary extremity soft tissue sarcomas.

ATPase activity of myosin in hair bundles of the bullfrog's sacculus

Mechanoelectrical transduction by a hair cell displays adaptation, which is thought to occur as myosin-based molecular motors within the mechanically sensitive hair bundle adjust the tension transmitted to transduction channels. To assess the enzymatic capabilities of the myosin isozymes in hair bundles, we examined the actin-dependent ATPase activity of bundles isolated from the bullfrog's sacculus. Separation of 32P-labeled inorganic phosphate from unreacted [gamma-32P]ATP by thin-layer chromatography enabled us to measure the liberation of as little as 0.1 fmol phosphate. To distinguish the Mg(2+)-ATPase activity of myosin isozymes from that of other hair-bundle enzymes, we inhibited the interaction of hair-bundle myosin with actin and determined the reduction in ATPase activity. N-ethylmaleimide (NEM) decreased neither physiologically measured adaptation nor the nucleotide-hydrolytic activity of a 120-kDa protein thought to be myosin 1 beta. The NEM-insensitive, actin-activated ATPase activity of myosin increased from 1.0 fmol x s-1 in 1 mM EGTA to 2.3 fmol x s-1 in 10 microM Ca2+. This activity was largely inhibited by calmidazolium, but was unaffected by the addition of exogenous calmodulin. These results, which indicate that hair bundles contain enzymatically active, Ca(2+)-sensitive myosin molecules, are consistent with the role of Ca2+ in adaptation and with the hypothesis that myosin forms the hair cell's adaptation motor.

Quasi-native chaperonin-bound intermediates in facilitated protein folding

Chaperonins are known to facilitate protein folding, but their mechanism of action is not well understood. The fact that target proteins are released from and rebind to different chaperonin molecules ("cycling") during a folding reaction suggests that chaperonins function by unfolding aberrantly folded molecules, allowing them multiple opportunities to reach the native state in bulk solution. Here we show that the cycling of alpha-tubulin by cytosolic chaperonin (c-cpn) can be uncoupled from the action of cofactors required to complete the folding reaction. This results in the accumulation of folding intermediates which are chaperonin-bound, stable, and quasi-native in that they bind GTP nonexchangeably. We present evidence that these intermediates can be generated without the target protein leaving c-cpn. These data show that, in contrast to prevailing models, target proteins can maintain, and possibly acquire, significant native-like structure while chaperonin-bound.

Specificity in chaperonin-mediated protein folding

Chaperonins are ubiquitous multisubunit toroidal complexes that aid protein folding in an ATP-dependent manner. Current models of folding by the bacterial chaperonin GroEL depict its role as unfolding and releasing molecules that have misfolded, so that they can return to a potentially productive folding pathway in solution. Accordingly, a given target polypeptide might require several cycles of binding and ATP-driven release from different chaperonin complexes before reaching the native state. Surprisingly, cycling of a target protein does not guarantee its folding, and we report here that unfolded beta-actin or alpha-tubulin both form tight complexes when presented to either GroEL or its mitochondrial homologue, and both undergo cycles of release and rebinding upon incubation with ATP, but no native protein is produced. We conclude that different chaperonins produce distinctive spectra of folding intermediates.