Validating the usefulness of Sudoscan in ATTRv: a single centre experience

BACKGROUND

Variant transthyretin amyloidosis (ATTRv) can cause sensorimotor and autonomic neuropathy. Objective quantification of sudomotor function may be essential for early diagnosis and early initiation of treatment. The aim of this study is to evaluate the diagnostic value of the Sudoscan® in ATTRv.

METHODS

Electrochemical skin conductance (ESC) was measured in V30M ATTRv patients, asymtomatic V30M carriers and healthy controls. Comparisons between the three groups were made using the Kruskal-Wallis test, and ROC curves were used to estimate the discriminatory power of ESC values between groups.

RESULTS

ESC was measured in 52 ATTRv patients, 107 asymptomatic carriers and 40 healthy controls. ESC was significantly lower in ATTRv patients compared to asymptomatic carriers and healthy controls in both feet and hands; median values are as follows: 40 µS, 78 µS and 81 µS, respectively (p < 0.001), and 53 µS, 69 µS and 74 µS, respectively (p < 0.001). ESC in feet < 70.5 µS had a sensitivity of 89.7% and specificity of 84.6% to discriminate asymptomatic carriers from patients with ATTRv.

CONCLUSION

The determination of ESC by Sudoscan® is a rapid, noninvasive and easily reproducible technique capable of discriminating patients with ATTRv from asymptomatic carriers and healthy controls with adequate sensitivity and specificity.

Integrated preclinical and clinical development of mTOR inhibitors in pancreatic cancer

BACKGROUND

The purpose of this work was to determine the efficacy of inhibiting mammalian target of rapamycin (mTOR) in pancreatic cancer preclinical models and translate preclinical observations to the clinic.

METHODS

Temsirolimus (20 mg Kg(-1) daily) was administered to freshly generated pancreatic cancer xenografts. Tumour growth inhibition was determined after 28 days. Xenografts were characterised at baseline by gene expression and comparative genomic hybridisation. Patients with advanced, gemcitabine-resistant pancreatic cancer were treated with sirolimus (5 mg daily). The primary end point was 6-month survival rate (6mSR). Correlative studies included immunohistochemistry assessment of pathway expression in baseline tumours, drug pharmacokinetics (PKs), response assessment by FDG-PET and pharmacodynamic effects in peripheral-blood mononuclear cells (PBMCs).

RESULTS

In all, 4 of 17 xenografts (23%) responded to treatment. Sensitive tumours were characterised by gene copy number variations and overexpression of genes leading to activation of the PI3K/Akt/mTOR pathway. Activation of p70S6K correlated with drug activity in the preclinical studies. Sirolimus was well tolerated in the clinic, showed predictable PKs, exerted pathway inhibition in post-treatment PBMCs and resulted in a 6mSR of 26%. No correlation, however, was found between activated p70S6K in tumour tissues and anti-tumour effects.

CONCLUSION

Sirolimus activity in pancreatic cancer was marginal and not predicted by the selected biomarker.

Activity of gemcitabine in direct patient-derived xenografts and clinical outcome: Validation of an in vivo model for drug development

4528

Background: Novel drugs are urgently needed for pancreatic ductal adenocarcinoma (PDA). Current preclinical models may not recapitulate the biology of human cancers. Direct xenografts have the potential to better represent the biology of human cancer. We have completed a clinical trial in which surgically resected PDAs were xenografted into nude mice thus generating an in vivo platform for drug development and biomarker identification. Methods: PDAs resected at Johns Hopkins Hospital are implanted into nude mice. From November 2005 to December 2008, 240 patients were consented, 236 operated, 102 were resectable PDAs thus fulfilling the inclusion criteria. 104 patients had other histologies and 34 were unresectable PDAs. Xenografted tumors were treated with gemcitabine and the activity in the xenograft correlated with patient clinical outcome. Results: Out of these 102 cases, 77 were xenografted, 53 were engrafted and reached the treatment phase. 35 out of the 53 originator patients were clinically treated with gemcitabine. The median overall survival of resected patients was 646 days (similar to 660 days from CONKO-001 trial). Patients whose carcinomas engrafted had a shorter median overall survival (319 vs. 728 days, p=0.002), probably reflecting a more aggressive tumor biology in the engrafted group. The response rate of gemcitabine in xenografts based on RECIST criteria was 8% (similar to response rate to gemcitabine in phase III trial by Moore et al.). In the adjuvant setting, the median disease free survival (DFS) was significantly longer in those patients predicted as sensitive by the xenograft model (568 vs. 286 days, p=0.037). In the metastatic setting, the median time to progression (TTP) was longer in those patients predicted as sensitive by the model (126 vs. 73 days) though this difference was not statistically significant. Overall the correlation between gemcitabine activity in this model and clinical outcome as measured by DFS was 0.71 in the subgroup of patients whose xenografts had a TGI lower than -10%. Conclusions: This preclinical model predicts gemcitabine outcome in the clinic in the adjuvant setting. Further studies to analyze the causes of shorter survival in patients whose PDA engrafted are warranted.

No significant financial relationships to disclose.

Use of amolecular mimicry approach to identify effective agents in pancreatic cancer

4603

Background: We proposed a molecular mimicry approach (prêt-à-porter), based on pathway-expression signatures that systematically connect a query case with the most similar profile from a reference profile database and extrapolates the most effective drug for personalized medicine. Here we report the pre-clinical and clinical validation of this concept in pancreatic cancer treatment. Methods: Baseline gene expression profiles of 24 patients that received gemcitabine as adjuvant chemotherapy were collected. A patient is defined as sensitive and resistant to gemcitabine if the disease free survival (DFS) is more and less than 300 days, respectively. We also performed a small scale pre-clinical study on comparing patient-derived xenografts refractory to gemcitabine in a second-line treatment of prêt-à-porter choice of drugs vs. one-size-fits-all choice of drug (erlotinib). Four gemcitabine resistant xenografts were randomly assigned into control, erlotinib and the prêt-à-porter choice of drug groups. Tumor growth inhibition values (TGI) were calculated at the end of the experiment. Results: Using the molecular mimcry concept, where a patient is connected to a sensitive cell line, s/he will be predicted as sensitive to gemcitabine and vice versa. The prêt-à-porter achieved an overall prediction accuracy of 71% on these retrospective patient samples. Our approach correctly classified 67% and 75% of the patients that were sensitive and resistant to gemcitabine as adjuvant chemotherapy, respectively. The median DFS for the sensitive and resistant groups are 491 and 162 days, respectively. This difference was statistically significant (log-rank test, p = 0.04). Furthermore, the mean TGI% for the prêt-à-porter is about 10-fold lower than the erlotinib arm (3% vs. 30%, Chi-square test, p = 0.02) in the pre-clinical study. This demonstrates that prêt-à-porter approach can be used to tailor personalized medicine and achieved better clinical response as compared to the current treatment approach. Conclusions: We comprehensively validated the prêt-à-porter approach in pre-clinical and clinical data and demonstrated that this approach can be used as a powerful translation research tool in enriching patient selection of novel drugs in clinical trials and realizing personalized medicine.

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Preclinical identification of biomarkers of response to mTOR inhibitors and subsequent application in a phase II trial of sirolimus in pancreatic cancer patients refractory to gemcitabine

4612

Background: Treatment for advanced pancreatic cancer refractory to gemcitabine has not been defined. We conducted an efficacy study in pancreatic cancer xenografts to identify biomarkers of response to mTOR inhibition and attempted to translate the results by conducting a phase II trial of sirolimus in this patient population. Methods: 19 direct pancreatic xenografts were treated with temsirolimus (20mg/Kg IP daily) for 28 days. Tumors were profiled with array CGH and gene expression arrays at baseline. TGI were calculated at 28 days. Patients refractory to gemcitabine were included in the clinical trial. Sirolimus was administered at 5mg/day for 28 days. Primary endpoint was 6 month survival rate (6mSR). Secondary endpoints included: baseline evaluation of AKT pathway activation, pharmacodynamic assessment of p-S6K in PBMC, pharmacokinetics and toxicity analysis. Results: In the preclinical study, mTOR sensitive tumors showed upregulation of genes involved in the renal cell cancer pathway. CGH identified focal gains in N-Ras and K-Ras and homozygous deletions of FHIT in sensitive cases. Overall, these genetic changes induced AKT pathway activation, and led us to explore high baseline p-S6K expression as a predictor of outcome in the clinical phase. Patient characteristics: Median age: 64 (39–77). 11 patients had received ≥ 2 prior lines of chemotherapy. 6mSR was 20%. 6mSR in the subgroup of patients who received rapamycin as first line chemotherapy after progression to gemcitabine was 34%. Baseline tumor p-S6K was not predictive for survival. Early pharmacodynamic changes in p-S6K in PBMC 6 hours after treatment initiation were correlated with survival (R2= 0.65). Treatment was well tolerated. The most common grade 3 adverse event was hyperglycemia in 10% of the patients. 7 (23%) patients achieved stable disease. Conclusions: Rapamycin is well tolerated in this setting. Early pharmacodynamic changes in p-S6K in PBMC were correlated with survival. Preclinical findings leading to activation of the AKT pathway in all sensitive cases warrants further validation studies. Efficacy data is limited by the selection of a heavily pretreated and poor prognosis population (DFS≤47 days).

No significant financial relationships to disclose.