High exosomal PD-L1 expression in relation to lymph node progression in metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone (abi) or enzalutamide (enza)

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Background: Programmed death-ligand 1 (PD-L1) has been recently found in tumor-derived exosomes and associated with progressive disease (PD) ( Poggio, Cell 2019). In localized prostate cancer, PD-L1 tumor expression has been shown to be a biomarker for node-positive patients (pts) ( Petitprez, Eur Urol Focus 2019) but its role in mCRPC is largely unexplored. We aimed to determine the potential of PD-L1 exosomal expression to predict lymph nodal PD in mCRPC receiving abi or enza. Methods: In a biomarker prospective study (REC 2192/2013), exosomes were isolated from plasma samples collected before first-line therapy with abi/enza between December 2014 and October 2018. RNA was extracted for analysis of PD-L1 by digital droplet PCR ( Del Re, Prostate Cancer Prostatic Dis 2021). Results: In our cohort of 55 node-positive mCRPC pts (median age: 76 years, range 47-89), the amount of exosomal PD-L1 expression (pts dichotomized in “high” and “low” as below or above median PD-L1/ACTB ratio = 0.0052) was associated with radiographic response after the first 3 months abi/enza therapy [high PD-L1 vs low PD-L1: 8 (25.8%) vs 0 (0%) PD, 23 (74.2%) vs 18 (75%) stable disease, and 0 vs 6 (25%) partial/complete response] (p = 0.0009). We observed an overall median progression-free survival (PFS) of 14.3 months [95% confidence interval (CI) 8.6-not reached] shorter in high PD-L1 compared to low PD-L1 10.6 (6.5-23.4) vs not reached [hazard ratio (HR) 3.1 (95% CI 1.1-8.5), p = 0.023]. In multivariable analysis including exosomal PD-L1 and androgen receptor (AR) variant 7, AR copy number gain detected in plasma, neutrophil lymphocyte ratio (NLR), lactate dehydrogenase, exosomal PD-L1; AR-V7 and AR gain were independent predictors of nodal PFS (HR 5.8, 95% CI 1.4-24.2, p = 0.01, HR 3.2, 95% CI 1.1-9.2, p = 0.03 and HR 12.9, 95% CI 2.3-73.2, p = 0.004), whereas AR-V7, AR gain, NLR > 3 were independent predictors of OS (HR 4.9, 95% CI 1.8-13.1, p = 0.001, HR 4.4, 95% CI 1.1-17, p = 0.02, and HR 3.2 95% CI 1.1-9.4, p = 0.03, respectively). Moreover, a trend of a worse OS was reported in high PD-L1 compared to low PD-L1 pts (HR 2.6, 95% CI 0.9-7.5, p = 0.07). Conclusions: In mCRPC pts treated with ARSI, exosomal PD-L1 expression may be considered as a predictive biomarker of lymph nodal response, playing a potential role in individualized disease monitoring and treatment combining between ARSI and immunotherapy. Larger evaluation of treatment decisions based on exosomal PD-L1 expression is now required.

Androgen receptor gain in circulating free DNA and splicing variant 7 in exosomes predict clinical outcome in CRPC patients treated with abiraterone and enzalutamide

BACKGROUND

Androgen receptor (AR) signaling inhibitors represent the standard treatment in metastatic castration resistance prostate cancer (mCRPC) patients. However, some patients display a primary resistance, and several studies investigated the role of the AR as a predictive biomarker of response to treatment. This study is aimed to evaluate the role of AR in liquid biopsy to predict clinical outcome to AR signaling inhibitors in mCRPC patients.

METHODS

Six milliliters of plasma samples were collected before first-line treatment with abiraterone or enzalutamide. Circulating free DNA (cfDNA) and exosome-RNA were isolated for analysis of AR gain and AR splice variant 7 (AR-V7), respectively, by digital droplet PCR.

RESULTS

Eighty-four mCRPC patients received abiraterone (n = 40) or enzalutamide (n = 44) as first-line therapy. Twelve patients (14.3%) presented AR gain and 30 (35.7%) AR-V7+ at baseline. Median progression-free survival (PFS) and overall survival (OS) were significantly longer in AR-V7- vs AR-V7+ patients (24.3 vs 5.4 months, p < 0.0001; not reached vs 16.2 months, p = 0.0001, respectively). Patients carrying the AR gain had a median PFS of 4.8 vs 24.3 months for AR normal patients (p < 0.0001). Median OS was significantly longer in AR normal vs patients with AR gain (not reached vs 8.17 months, p < 0.0001). A significant correlation between AR-V7 and AR gain was observed (r = 0.28; p = 0.01). The AR gain/AR-V7 combined analysis confirmed a strong predictive effect for biomarkers combination vs patients without any AR aberration (PFS 3.8 vs 28 month, respectively; OS 6.1 vs not reached, respectively; p < 0.0001).

CONCLUSIONS

The present study demonstrates that cfDNA and exosome-RNA are both a reliable source of AR variants and their combined detection in liquid biopsy predicts resistance to AR signaling inhibitors.

Artificial intelligence, radiomics and other horizons in body composition assessment

This paper offers a brief overview of common non-invasive techniques for body composition assessment methods, and of the way images extracted by these methods can be processed with artificial intelligence (AI) and radiomic analysis. These new techniques are becoming more and more appealing in the field of health care, thanks to their ability to treat and process a huge amount of data, suggest new correlations between extracted imaging biomarkers and traits of several diseases as well as lead to the possibility to realise an increasingly personalized medicine. The idea is to suggest the use of AI applications and radiomic analysis to search for features that may be extracted from medical images [computed tomography (CT) and magnetic resonance imaging (MRI)], and that may turn out to be good predictors of metabolic disorder diseases and cancer. This could lead to patient-specific treatments and management of several diseases linked with excessive body fat.

PRIMAGE project: predictive in silico multiscale analytics to support childhood cancer personalised evaluation empowered by imaging biomarkers

PRIMAGE is one of the largest and more ambitious research projects dealing with medical imaging, artificial intelligence and cancer treatment in children. It is a 4-year European Commission-financed project that has 16 European partners in the consortium, including the European Society for Paediatric Oncology, two imaging biobanks, and three prominent European paediatric oncology units. The project is constructed as an observational in silico study involving high-quality anonymised datasets (imaging, clinical, molecular, and genetics) for the training and validation of machine learning and multiscale algorithms. The open cloud-based platform will offer precise clinical assistance for phenotyping (diagnosis), treatment allocation (prediction), and patient endpoints (prognosis), based on the use of imaging biomarkers, tumour growth simulation, advanced visualisation of confidence scores, and machine-learning approaches. The decision support prototype will be constructed and validated on two paediatric cancers: neuroblastoma and diffuse intrinsic pontine glioma. External validation will be performed on data recruited from independent collaborative centres. Final results will be available for the scientific community at the end of the project, and ready for translation to other malignant solid tumours.

Incidence of T790M in Patients With NSCLC Progressed to Gefitinib, Erlotinib, and Afatinib: A Study on Circulating Cell-free DNA

BACKGROUND

Insights into the mechanism of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) could provide important information for further patient management, including the choice of second-line treatment. The EGFR T790M mutation is the most common mechanism of resistance to first- and second-generation EGFR TKIs. Owing to its biologic relevance in the response of non-small-cell lung cancer (NSCLC) to the selective pressure of treatment, the present study investigated whether the occurrence of T790M at progression differed among patients receiving gefitinib, erlotinib, or afatinib.

PATIENTS AND METHODS

The present retrospective study included patients with NSCLC with an EGFR activating mutation, who had received gefitinib, erlotinib, or afatinib as first-line treatment. Plasma samples for the analysis of cell-free DNA were taken at disease progression and analyzed using a digital droplet polymerase chain reaction EGFR mutation assay.

RESULTS

A total of 83 patients were enrolled; 42 had received gefitinib or erlotinib and 41afatinib. The patient characteristics were comparable across the 2 groups. The median time to progression (TTP) was 14.4 months for the gefitinib and erlotinib group and 10.2 months for the afatinib group (P = .09). Of the 83 patients, 47 (56.6%) were positive for the T790M in plasma. A greater incidence of T790M was observed in patients with progression during gefitinib or erlotinib therapy compared with patients treated with afatinib (33 [79%] vs. 14 [34%], respectively; odds ratio, 7.1; 95% confidence interval, 2.7-18.5; P = .0001).

CONCLUSIONS

Although gefitinib, erlotinib, and afatinib showed a comparable TTP in patients receiving first-line therapy, the incidence of T790M differed among them, as demonstrated by the present study, which could have implications for the choice of second-line treatment.

Endothelial nitric oxide synthase c.-813C>T predicts for proteinuria in metastatic breast cancer patients treated with bevacizumab-based chemotherapy

PURPOSE

To investigate the association between single nucleotide polymorphisms (SNPs) in endothelial nitric oxide synthase (eNOS) and interleukin-8 (IL-8) genes and risk of developing bevacizumab-related adverse events in metastatic breast cancer (mBC) patients.

PATIENTS AND METHODS

mBC patients candidate to receive bevacizumab-based chemotherapy were enrolled in this pharmacogenetic study. eNOS c.-813C>T and c.894G>T, and IL-8 c.-251A>T were analyzed by real time PCR on genomic DNA extracted from peripheral blood. Univariate analysis was performed to test the association between each SNP and treatment-related toxicities.

RESULTS

Seventy-six mBC patients were enrolled in the present study. Patients carrying the homozygous variant eNOS c.-813TT genotype showed a statistically significant occurrence of any grade proteinuria when compared to CT or CC genotypes (p = 0.004). No significant association of proteinuria with IL-8 SNP or hypertension with selected eNOS and IL-8 SNPs was found.

CONCLUSIONS

These findings suggest an association between the eNOS c.-813C>T polymorphism and the development of proteinuria in mBC patients receiving a bevacizumab-based chemotherapy.

Understanding the Mechanisms of Resistance in EGFR-Positive NSCLC: From Tissue to Liquid Biopsy to Guide Treatment Strategy

Liquid biopsy has emerged as an alternative source of nucleic acids for the management of Epidermal Growth Factor Receptor (EGFR)-mutant non-Small Cell Lung Cancer (NSCLC). The use of circulating cell-free DNA (cfDNA) has been recently introduced in clinical practice, resulting in the improvement of the identification of druggable EGFR mutations for the diagnosis and monitoring of response to targeted therapy. EGFR-dependent (T790M and C797S mutations) and independent (Mesenchymal Epithelial Transition [MET] gene amplification, Kirsten Rat Sarcoma [KRAS], Phosphatidyl-Inositol 4,5-bisphosphate 3-Kinase Catalytic subunit Alpha isoform [PI3KCA], and RAF murine sarcoma viral oncogene homolog B1 [BRAF] gene mutations) mechanisms of resistance to EGFR tyrosine kinase inhibitors (TKIs) have been evaluated in plasma samples from NSCLC patients using highly sensitive methods (i.e., digital droplet PCR, Next Generation Sequencing), allowing for the switch to other therapies. Therefore, liquid biopsy is a non-invasive method able to detect the molecular dynamic changes that occur under the pressure of treatment, and to capture tumor heterogeneity more efficiently than is allowed by tissue biopsy. This review addresses how liquid biopsy may be used to guide the choice of treatment strategy in EGFR-mutant NSCLC.

From the beginning to resistance: Study of plasma monitoring and resistance mechanisms in a cohort of patients treated with osimertinib for advanced T790M-positive NSCLC

INTRODUCTION

Analysis of circulating tumor DNA (ctDNA) for the identification of T790M mutation in advanced EGFR-mutated NSCLC patients can replace tissue re-biopsy for resistance characterization and, being non-invasive, may be applied for disease monitoring. We analysed ctDNA during osimertinib treatment to correlate mutational levels with clinical outcome and to predict pattern of resistance.

MATERIALS AND METHODS

Forty patients with advanced NSCLC receiving osimertinib for T790M + disease after previous EGFR-TKI were enrolled in a pilot study to collect plasma at baseline and every 12 weeks until progression. Molecular analysis of ctDNA was performed by ddPCR and Therascreen®. When feasible at progression, tissue re-biopsy and NGS analysis were performed.

RESULTS

Thirty-eight patients had baseline plasma samples suitable for molecular analysis. Patients with low levels of the EGFR activating mutation in ctDNA [< 2200 copies/mL or allele frequency (AF) < 6.1%] showed better progression-free survival (17.8 or 17.8 months vs. 4.3 or 2.7, p = 0.022 or p = 0.018, respectively) and overall survival (23.6 or 23.6 vs. 7.7 or 7.3, p = 0.016 or p = 0.013, respectively) than patients with high levels (≥ 2200 copies/mL or AF ≥ 6.1%). Patients with detectable EGFR mutations in plasma (shedders) presented worse outcome than negative subjects (non-shedders). Low levels of T790M, higher T790M/activating mutation ratio and complete clearance after 2 months were associated with a trend towards better outcome. Tissue re-biopsy at resistance showed 3 patients with EGFR C797S, 1 with MET amplification, 1 with MYC amplification, 1 with PTEN loss, 3 with SCLC transformation.

CONCLUSIONS

The mutational analysis performed on plasma plays a significant role in prognostic stratification, especially for the EGFR activating mutation, since patients with absence or low levels of mutations presented a better outcome to osimertinib. At progression, tissue re-biopsy remains a crucial issue for the identification of resistance mechanisms.

The amount of activating EGFR mutations in circulating cell-free DNA is a marker to monitor osimertinib response

BACKGROUND

Circulating cell-free DNA (cfDNA) may help understand the molecular response to pharmacologic treatment and provide information on dynamics of clonal heterogeneity. Therefore, this study evaluated the correlation between treatment outcome and activating EGFR mutations (act-EGFR) and T790M in cfDNA in patients with advanced NSCLC given osimertinib.

METHODS

Thirty-four NSCLC patients resistant to first/second-generation EGFR-TKIs, positive for both act-EGFR and T790M in cfDNA at the time of progression were enrolled in this study. Plasma samples were obtained at osimertinib baseline and after 3 months of therapy; cfDNA was analyzed by droplet digital PCR and results were expressed as mutant allele frequency (MAF).

RESULTS

At baseline, act-EGFR MAF was significantly higher than T790M (p < 0.0001). act-EGFR MAF and T790M/act-EGFR MAF ratio were significantly correlated with disease response (p = 0.02). Cut-off values of act-EGFR MAF and T790M/act-EGFR ratio of 2.6% and 0.22 were found, respectively. The PFS of patients with act-EGFR MAF of > 2.6% and < 2.6%, were 10 months vs. not reached, respectively (p = 0.03), whereas patients with T790M/act-EGFR ≤ 0.22 had poorer PFS than patients with a value of > 0.22 (6 months vs. not reached, respectively, p = 0.01).

CONCLUSION

act-EGFR MAF and T790M/act-EGFR MAF ratio are potential markers of outcome in patients treated with osimertinib.

Pharmacogenetics and Metabolism from Science to Implementation in Clinical Practice: The Example of Dihydropyrimidine Dehydrogenase

BACKGROUND

Fluoropyrimidines are widely used in the treatment of solid tumors and remain the backbone of many combination chemotherapy regimens. Despite their clinical benefit, they are associated with frequent gastrointestinal and hematological toxicities, which often lead to treatment discontinuation. Fluoropyrimidines undergo complex anabolic and catabolic biotransformation. Enzymes involved in this pathway include dihydropyrimidine dehydrogenase (DPD), which breaks down 5-FU and its prodrugs. Candidate gene approaches have demonstrated associations between 5-FU treatment outcomes and germline polymorphisms in DPD. The aim of this review is to report and discuss the latest results on fluoropyrimidine pharmacogenetics.

METHODS

Literature from PubMed databases and bibliography from retrieved publications have been analyzed according to terms such DPD, DPYD, fluoropyrimdines, polymorphisms, toxicity, pharmacogenetics.

RESULTS

To date, many sequence variations have been identified within DPYD gene, although the majority of these have no functional consequences on enzymatic activity. Nowadays, there is a general agreement on the clinical significance of the importance of DPD deficiency in patients who suffer from severe, life-threatening drug toxicity although preemptive testing is not applied to all patients.

CONCLUSION

Considering the published literature, clinicians are strongly encouraged to consider testing for DPD poor metabolizer variants as a rational pre-treatment screening for patients candidate to a fluoropyrimidine-based regimens, in order to prevent toxicities and personalise treatments.

PD-L1 mRNA expression in plasma-derived exosomes is associated with response to anti-PD-1 antibodies in melanoma and NSCLC

Background:

PD-L1 expression in tumour tissues is widely used to select patients to receive anti-PD-1/PD-L1 antibodies, but data are lacking on the correlation of plasma PD-L1 levels with the effect of treatments.

Methods:

To investigate the association between PD-L1 mRNA in plasma-derived exosomes and response to nivolumab and pembrolizumab in patients with melanoma (n=18) and NSCLC (n=8), blood was obtained at time point 0 and after 2 months. Exosomal PD-L1 mRNA was measured by digital droplet PCR.

Results:

The mean±s.e.m. PD-L1 levels in patients with complete and partial responses were 830.4±231.3 and 242.5±82.5 copies per ml at time 0 vs 2 months, respectively (P=0.016). In patients with stable disease the mean±s.e.m. values were 298.8±97.2 vs 247.5±29.8 copies per ml (P=0.586), while in progressive disease, PD-L1 mRNA levels were 204.0±68.8 vs 416.0±87.8 copies per ml at time 0 vs 2 months, respectively (P=0.001).

Conclusions:

This study demonstrates that exosomal PD-L1 is significantly associated with response to treatment.

Concise Review: Chronic Myeloid Leukemia: Stem Cell Niche and Response to Pharmacologic Treatment

Nowadays, more than 90% of patients affected by chronic myeloid leukemia (CML) survive with a good quality of life, thanks to the clinical efficacy of tyrosine kinase inhibitors (TKIs). Nevertheless, point mutations of the ABL1 pocket occurring during treatment may reduce binding of TKIs, being responsible of about 20% of cases of resistance among CML patients. In addition, the presence of leukemic stem cells (LSCs) represents the most important event in leukemia progression related to TKI resistance. LSCs express stem cell markers, including active efflux pumps and genetic and epigenetic alterations together with deregulated cell signaling pathways involved in self-renewal, such as Wnt/β-catenin, Notch, and Hedgehog. Moreover, the interaction with the bone marrow microenvironment, also known as hematopoietic niche, may influence the phenotype of surrounding cells, which evade mechanisms controlling cell proliferation and are less sensitive or frankly resistant to TKIs. This Review focuses on the role of LSCs and stem cell niche in relation to response to pharmacological treatments. A literature search from PubMed database was performed until April 30, 2017, and it has been analyzed according to keywords such as chronic myeloid leukemia, stem cell, leukemic stem cells, hematopoietic niche, tyrosine kinase inhibitors, and drug resistance. Stem Cells Translational Medicine 2018;7:305-314.

Association of PD-L1 mRNA levels in plasma-derived exosomes with response to nivolumab and pembrolizumab in melanoma and NSCLC

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Background: The anti-PD-1 monoclonal antibodies (moAb) nivolumab and pembrolizumab have improved the survival of melanoma and non-small cell lung cancer (NSCLC) patients. However, treatment selection is based on tumor PD-L1 expression by immuno-histochemistry and no specific approaches are available to monitor treatment response. The aim of this study was to investigate the association between PD-L1 mRNA levels in plasma-derived exosomes and response to nivolumab and pembrolizumab in patients affected by melanoma (n = 18) and NSCLC (n = 8). Methods: Blood (6 ml) was obtained at 1) baseline (before initiation of anti-PD1 moAb or at the time of last available radiological evaluation of disease response) and 2) after two months of treatment (at the time of first response evaluation or disease re-assessment). Exosomes were extracted from plasma and PD-L1 mRNA expression was measured by digital PCR and expressed as copies/ml. Results: Overall, the number of copies of mRNA PD-L1/ml plasma varied according to tumor response; in particular, an increase was found in patients with PD and a decrease was observed in patients who achieved a CR/PR. The mean±SEM values of PD-L1 in patients responding to treatment (CR+PR) were 830.4±231.3 and 242.5±82.5 copies/ml (baseline vs. 2 months, p = 0.016), respectively. In patients with stable disease the mean±SEM values were as expected 298.8±97.2 vs. 247.5±29.8 copies/ml (p = 0.586), while in progressive disease PD-L1 expression levels were 204.0±68.8 vs. 416.0±87.8 copies/ml (p = 0.001), respectively. Conclusions: In the present study, we demonstrate for the first time that changes in exosomal PD-L1 expression occur in melanoma and NSCLC patients treated with nivolumab or pembrolizumab and may correlate with the radiological tumor response. This proof-of-concept study demonstrates the feasibility of detecting PD-L1 in plasma and its relationship with response to treatment.

Concise Review: Resistance to Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer: The Role of Cancer Stem Cells

Among the potential mechanisms involved in resistance to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer, the manifestation of stem-like properties in cancer cells seems to have a crucial role. Alterations involved in the development of TKI resistance may be acquired in a very early phase of tumorigenesis, supporting the hypothesis that these aberrations may be present in cancer stem cells (CSCs). In this regard, the characterization of tumor subclones in the initial phase and the identification of the CSCs may be helpful in planning a specific treatment to target selected biomarkers, suppress tumor growth, and prevent drug resistance. The aim of this review is to elucidate the role of CSCs in the development of resistance to TKIs and its implication for the management of patients. Stem Cells 2018;36:633-640.

Implications of KRAS mutations in acquired resistance to treatment in NSCLC

Rationale

KRAS is the most common and, simultaneously, the most ambiguous oncogene implicated in human cancer. Despite KRAS mutations were identified in Non Small Cell Lung Cancers (NSCLCs) more than 20 years ago, selective and specific inhibitors aimed at directly abrogating KRAS activity are not yet available. Nevertheless, many therapeutic approaches have been developed potentially useful to treat NSCLC patients mutated for KRAS and refractory to both standard chemotherapy and targeted therapies.

The focus of this review will be to provide an overview of the network related to the intricate molecular KRAS pathways, stressing on preclinical and clinical studies that investigate the predictive value of KRAS mutations in NSCLC patients.

Materials and Methods

A bibliographic search of the Medline database was conducted for articles published in English, with the keywords KRAS, KRAS mutations in non-small cell lung cancer, KRAS and tumorigenesis, KRAS and TKIs, KRAS and chemotherapy, KRAS and monoclonal antibody, KRAS and immunotherapy, KRAS and drugs, KRAS and drug resistance.

Patients with NSCLC may display a low ratio of p.T790M vs. activating EGFR mutations in plasma at disease progression: implications for personalised treatment

Introduction

NSCLC harboring activating mutations of EGFR is highly sensitive to first-line EGFR-tyrosine kinase inhibitors (TKIs), but drug resistance depending on the EGFR mutation p.T790M will occur in about 50-60% of patients. Detailed information on the amount of p.T790M plasmatic level associated with resistance to EGFR-TKIs and guidance to treatment with p.T790M-effective TKI depending on these levels, is lacking.

Methods

This study enrolled p.T790M-positive patients (n=49) affected by EGFR-mutated NSCLC at progression to first-line EGFR-TKIs and, in selected cases (n=5), after second-line treatment with osimertinib. Cell-free circulating tumor DNA (cftDNA) was extracted from plasma and the quantitative analysis of EGFR ex19del, p.L858R and p.T790M was performed by digital droplet PCR.

Results

The mean amount of mutated alleles at progression to first-line EGFR-TKIs was 108,492 copies/ml for ex19del, 97,336 copies/ml for p.L858R, but only 8,754 copies/ml for p.T790M. There was no significant correlation between progression-free survival and the ratio of p.T790M over EGFR activating mutations. The analysis of cftDNA in 5 patients treated with osimertinib revealed a marked decrease of all EGFR mutant alleles.

Conclusions

The amount of p.T790M in plasma can be much lower than activating EGFR mutations. Despite this finding, osimertinib is effective in p.T790M-positive patients. These results indicate that clones driving resistance to EGFR-TKIs represent a minority among cells bearing activating EGFR-mutations. In addition, the identification of a threshold level of p.T790M is not a strict requirement for the selection of patients to be treated with osimertinib, since treatment showed a decrease in all EGFR mutated cells.

Unusual gastrointestinal and cutaneous toxicities by bleomycin, etoposide, and cisplatin: a case report with pharmacogenetic analysis to personalize treatment

The standard treatment of testicular germ cell tumors is based on the combination of bleomycin, etoposide, and cisplatin (PEB). However, this treatment may be associated with severe adverse reactions, such as hematological and non-hematological toxicities. Here, we report a case of a patient suffering from severe PEB-related toxicities, to whom pharmacogenetic analyses were performed, comprising a panel of genes involved in PEB metabolism. The analysis revealed the presence of a complex pattern of polymorphisms in GSTP1, UGT1A1 (TA)6/7, UGT1A7, and ABCB1. The present case shows that a pharmacogenetic approach can help in the management of adverse drug reactions in order to predict, prevent, and personalize treatments.

Variations of circulating KRAS amount as a biomarker to monitor chemotherapy response in pancreatic cancer

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Background: Current treatment of pancreatic ductal adenocarcinoma (PDAC) is FOLFIRINOX or gemcitabine + nab-paclitaxel, and CA19-9 is the only approved biomarker to monitor tumor response. However, CA19-9 has several limitations (i.e. sensitivity and specificity), highlighting the need for new biomarkers. Being the majority of PDAC (75-95%) KRAS mutated (mutKRAS), the present study developed an analysis tool based on circulating tumor DNA (ctDNA) to monitor the variation of mutKRAS in PDAC undergoing first-line chemotherapy. Early variation of ctDNA mutKRAS after 15 days of treatment was correlated with response to therapy. Methods: Three ml of plasma were collected from patients with PDAC undergoing first-line FOLFIRINOX or gemcitabine + nab-paclitaxel. Patients underwent standard disease evaluation by imaging according to RECIST 1.1 criteria. Blood samples were drawn prior to cycle 1, after 14 days and at each radiological evaluation. ctDNA was extracted using a QIAmp Circulating nucleic acid Kit (Qiagen, Valencia, CA) and the KRAS codon 12 and p.G13D analysis was performed by digital droplet PCR (ddPCR, BioRad, Hercules, CA). Results: A total of 27 patients with locally advanced (15%) and metastatic (85%) PDAC were included in this study. mutKRAS in ctDNA was detected in 19 patients (70.3%) at baseline. There were no statistically significant differences in median PFS and OS in patients with baseline positive or negative ctDNA mutKRAS (p = 0.15). However, there was a statistically significant difference in PFS and OS between patients with increase vs. stability/reduction of ctDNA at the 14 day-evaluation (median PFS: 2.5 vs 7.5 months, p = 0.03; median OS: 9 vs 11.5 months p = 0.009). The imaging evaluation performed at 2 months after initiation of therapy demonstrated that all patients with an increase in ctDNA at 14 days had radiological progression of disease. Conclusions: The results of this pilot study support the use of ctDNA as a new marker for monitoring treatment outcome and disease progression in PDAC, suggesting that ctDNA mutKRAS is a non-invasive predictive factor of response in PDAC.

Detection of ALK and KRAS Mutations in Circulating Tumor DNA of Patients With Advanced ALK-Positive NSCLC With Disease Progression During Crizotinib Treatment

BACKGROUND

In patients with anaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC), disease progression occurs after a median of 9 to 10 months of crizotinib treatment. Several mechanisms of resistance have been identified and include ALK mutations and amplification or the activation of bypassing signaling pathways. Rebiopsy in NSCLC patients represents a critical issue and the analysis of circulating cell-free DNA (cfDNA) has a promising role for the identification of resistance mechanisms.

PATIENTS AND METHODS

Twenty patients with advanced ALK-positive NSCLC were enrolled after disease progression during crizotinib treatment; cfDNA was analyzed using digital droplet polymerase chain reaction (BioRad, Hercules, CA) for ALK (p.L1196M, p.G1269A, and p.F1174L) and Kirsten rat sarcoma (KRAS) (codons 12 and 13) mutations.

RESULTS

ALK secondary mutations (p.L1196M, p.G1269A, and p.F1174L) were identified in 5 patients; 1 patient had 2 ALK mutations (p.L1196M and p.G1269A). Overall, 10 patients presented KRAS mutations (7 p.G12D, 2 p.G12V, and 1 p.G12C mutations, respectively). In 3 patients KRAS mutations were associated with ALK mutations. cfDNA was monitored during the treatment with second-generation ALK inhibitors and the amount of ALK as well as KRAS mutations decreased along with tumor regression.

CONCLUSION

ALK and KRAS mutations are associated with acquired resistance to crizotinib in ALK-positive NSCLC. In particular, ALK acquired mutations can be detected in plasma and could represent a promising tumor marker for response monitoring.

Critical focus on mechanisms of resistance and toxicity of m-TOR inhibitors in pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (pNETs) are rare neoplasms representing less than 2% of all pancreatic malignancies. The PI3K-AKT-mTOR pathway is often deregulated in pNETs and seems to play a key role in tumorigenesis. Everolimus, an inhibitor of the mTOR pathway, has demonstrated efficacy in the treatment of pNETs. Nevertheless de novo or acquired drug resistance is responsible for disease progression and represents a major obstacle to overcome by clinicians. Blocking the PI3K/AKT/mTOR pathway may cover the supposed main mechanisms of resistance to everolimus. Therefore, BEZ-235, a potent oral dual PI3K/mTOR inhibitor was investigated in clinical trials. Globally more than 250 patients with different types of solid tumors were treated. Two studies were conducted in pNETs with BEZ-235 as single agent. The former was a phase 2 trial conducted in pNETs resistant to everolimus while the latter a randomized trial comparing everolimus and BEZ-235. Unfortunately, both the studies disappointed the expectations and were prematurely halted mainly due to severe toxicity. On this basis we reviewed m-TOR inhibitors in pNETs, focusing on their mechanisms of resistance and toxicity.