The new method of ZnIn2S4 synthesis on the titania nanotubes substrate with enhanced stability and photoelectrochemical performance

In this work, ZnIn2S4 layers were obtained on fluorine doped tin oxide (FTO) glass and TiO2 nanotubes (TiO2NT) using a hydrothermal process as photoanodes for photoelectrochemical (PEC) water splitting. Then, samples were annealed and the effect of the annealing temperature was investigated. Optimization of the deposition process and annealing of ZnIn2S4 layers made it possible to obtain an FTO-based material generating a photocurrent of 1.2 mA cm-2 at 1.62 V vs. RHE in a neutral medium. In contrast, the highest photocurrent in the neutral electrolyte obtained for the TiO2NT-based photoanode reached 0.5 mA cm-2 at 1.62 V vs. RHE. In addition, the use of a strongly acidic electrolyte allowed the generated photocurrent by the TiO2NT-based photoanode to increase to 3.02 mA cm-2 at 0.31 V vs. RHE. Despite a weaker photoresponse in neutral electrolyte than the optimized FTO-based photoanode, the use of TiO2NT as a substrate allowed for a significant increase in the photoanode's operating time. After 2 h of illumination, the photocurrent response of the TiO2NT-based photoanode was 0.21 mA cm-2, which was 42% of the initial value. In contrast, the FTO-based photoanode after the same time generated a photocurrent of 0.02 mA cm-2 which was only 1% of the initial value. The results indicated that the use of TiO2 nanotubes as a substrate for ZnIn2S4 deposition increases the photoanode's long-term stability in photoelectrochemical water splitting. The proposed charge transfer mechanism suggested that the heterojunction between ZnIn2S4 and TiO2 played an important role in improving the stability of the material by supporting charge separation.

Sequencing paired tumor DNA and white blood cells improves circulating tumor DNA tracking and detects pathogenic germline variants in localized colon cancer

BACKGROUND

In the setting of localized colon cancer (CC), circulating tumor DNA (ctDNA) monitoring in plasma has shown potential for detecting minimal residual disease (MRD) and predicting a higher risk of recurrence. With the tumor-only sequencing approach, however, germline variants may be misidentified as somatic variations, precluding the possibility of tracking in up to 11% of patients due to a lack of known somatic mutations. In this study, we assess the potential value of adding white blood cells (WBCs) to tumor tissue sequencing to enhance the accuracy of sequencing results.

PATIENTS AND METHODS

A total of 148 patients diagnosed with localized CC were prospectively recruited at the Hospital Clínico Universitario in Valencia (Spain). Employing a custom 29-gene panel, sequencing was conducted on tumor tissue, plasma and corresponding WBCs. Droplet digital PCR and amplicon-based NGS were performed on plasma samples post-surgery to track MRD. Oncogenic somatic variants were identified by annotating with COSMIC, OncoKB and an internal repository of pathogenic mutations database. A variant prioritization analysis, mainly characterized by the match of oncogenic mutations with the evidence levels defined in OncoKB, was carried out to select specific targeted therapies.

RESULTS

Utilizing paired tumor and WBCs sequencing, we identified somatic mutations in all patients (100%) within our cohort, compared to 89% using only tumor tissue. Consequently, the top 10 most frequently mutated genes for plasma monitoring were altered. The sequencing of WBCs identified 9% of patients with pathogenic mutations in the germline, with APC and TP53 being the most frequently mutated genes. Additionally, mutations in genes related to clonal hematopoiesis of indeterminate potential were detected in 27% of the cohort, with TP53, KRAS, and KMT2C being the most frequently altered genes. There were no observed differences in the sensitivity of monitoring MRD using ddPCR or amplicon-based NGS (p = 1). Ultimately, 41% of the patients harbored potentially targetable alterations at diagnosis.

CONCLUSION

The germline testing method not only enhanced sequencing results and raised the proportion of patients eligible for plasma monitoring, but also uncovered the existence of pathogenic germline variations, thereby aiding in the identification of patients at a higher risk of hereditary cancer syndromes.

Towards precision oncology for HER2 blockade in gastroesophageal adenocarcinoma

Gastroesophageal adenocarcinoma (GEA) represents a very heterogeneous disease and patients in advanced stages have a very poor prognosis. Although several molecular classifications have been proposed, precision medicine for HER2-amplified GEA patients still represents a challenge. Despite improvement in clinical outcomes obtained by adding trastuzumab to first-line platinum-based chemotherapy, no other anti-HER2 agents used first-line or beyond progression have demonstrated any benefit. Several factors contribute to this failure. Among them, variable HER2 amplification assessment, tumour heterogeneity, molecular mechanisms of resistance and microenvironmental factors could limit the effectiveness of anti-HER2 blockade. Identifying the factors responsible for both primary and acquired resistance is a priority for providing an improved, personalised approach. In this review, we examine current treatments for HER2-amplified GEA, their potential mechanisms of resistance and the ways to overcome them, investigating the most relevant translational studies with anti-HER2 agents in GEA, as well as novel agents under development in this field.

The role of tumor-associated macrophages in gastric cancer development and their potential as a therapeutic target

Gastric cancer (GC) represents the fifth cause of cancer-related death worldwide. Molecular biology has become a central area of research in GC and there are currently at least three major classifications available to elucidate the mechanisms that drive GC oncogenesis. Further, tumor microenvironment seems to play a crucial role, and tumor-associated macrophages (TAMs) are emerging as key players in GC development. TAMs are cells derived from circulating chemokine- receptor-type 2 (CCR2) inflammatory monocytes in blood and can be divided into two main types, M1 and M2 TAMs. M2 TAMs play an important role in tumor progression, promoting a pro-angiogenic and immunosuppressive signal in the tumor. The diffuse GC subtype, in particular, seems to be strongly characterized by an immuno-suppressive and pro-angiogenic phenotype. No molecular targets in this subgroup have yet been identified. There is an urgent need to understand the molecular pathways and tumor microenvironment features in the GC molecular subtypes. The role of anti-angiogenics and checkpoint inhibitors has recently been clinically validated in GC. Both ramucirumab, a fully humanized IgG1 monoclonal anti-vascular endothelial growth factor receptor 2 (VEGFR2) antibody, and checkpoint inhibitors in Epstein Bar Virus (EBV) and Microsatellite Instable (MSI) subtypes, have proved beneficial in advanced GC. Nevertheless, there is a need to identify predictive markers of response to anti-angiogenics and immunotherapy in clinical practice for a personalized treatment approach. The importance of M2 TAMs in development of solid tumors is currently gaining increasing interest. In this literature review we analyze immune microenvironment composition and signaling related to M1 and M2 TAMs in GC as well as its potential role as a therapeutic target.

Targeted next-generation sequencing of circulating-tumor DNA for tracking minimal residual disease in localized colon cancer

BACKGROUND

A high percentage of patients diagnosed with localized colon cancer (CC) will relapse after curative treatment. Although pathological staging currently guides our treatment decisions, there are no biomarkers determining minimal residual disease (MRD) and patients are at risk of being undertreated or even overtreated with chemotherapy in this setting. Circulating-tumor DNA (ctDNA) can to be a useful tool to better detect risk of relapse.

PATIENTS AND METHODS

One hundred and fifty patients diagnosed with localized CC were prospectively enrolled in our study. Tumor tissue from those patients was sequenced by a custom-targeted next-generation sequencing (NGS) panel to characterize somatic mutations. A minimum variant allele frequency (VAF) of 5% was applied for variant filtering. Orthogonal droplet digital PCR (ddPCR) validation was carried out. We selected known variants with higher VAF to track ctDNA in the plasma samples by ddPCR.

RESULTS

NGS found known pathological mutations in 132 (88%) primary tumors. ddPCR showed high concordance with NGS (r = 0.77) for VAF in primary tumors. Detection of ctDNA after surgery and in serial plasma samples during follow-up were associated with poorer disease-free survival (DFS) [hazard ratio (HR), 17.56; log-rank P = 0.0014 and HR, 11.33; log-rank P = 0.0001, respectively]. Tracking at least two variants in plasma increased the ability to identify MRD to 87.5%. ctDNA was the only significantly independent predictor of DFS in multivariable analysis. In patients treated with adjuvant chemotherapy, presence of ctDNA after therapy was associated with early relapse (HR 10.02; log-rank P < 0.0001). Detection of ctDNA at follow-up preceded radiological recurrence with a median lead time of 11.5 months.

CONCLUSIONS

Plasma postoperative ctDNA detected MRD and identified patients at high risk of relapse in localized CC. Mutation tracking with more than one variant in serial plasma samples improved our accuracy in predicting MRD.

High frequency of radiological differential responses with poly(ADP-Ribose) polymerase (PARP) inhibitor therapy

Despite impressive clinical activity in patients with germline BRCA1 and BRCA2 (BRCA1/2) mutant cancers, antitumor responses to poly(ADP-Ribose) polymerase (PARP) inhibitors are variable. We set out to assess the rate of intrapatient radiological differential responses (RDR) to PARP inhibitors, its correlation with patient outcomes, and the identification of factors associated with RDR. We retrospectively reviewed all patients with advanced cancers from five early phase PARP inhibitor monotherapy trials. 113 patients (ovarian cancers 57.5%; breast cancers 23.9%) were included in this retrospective study; 46 (40.7%) patients developed RDR on PARP inhibitor monotherapy. We identified two patterns of RDR: early RDR (1st or 2nd on-treatment scans) in 69.6% of patients, and late RDR (penultimate or final scans) in 30.4% of patients. Early RDR was associated with shorter time to progression (TTP) (225 vs 367 days, HR:0.59, 95%CI 0.36-0.98; p=0.04) and overall survival (OS) (499 vs 857 days; HR:0.47, 95%CI 0.27-0.82, p=0.006). Seventy-nine (69.9%) patients had known germline BRCA1/2 mutations; 49.4% of these BRCA1/2 mutation carriers developed RDR versus 20.6% of patients with unknown or wildtype BRCA1/2 status. Harboring germline BRCA1/2 mutations was independently predictive for RDR (RR:2.93, 95% CI 1.08-7.90, p=0.03). Patients with germline BRCA1 mutations had worse TTP and OS than BRCA2 mutation carriers (212 vs 406 days, HR:0.58, 95% CI 0.36-0.94, p=0.023 and 515 vs 937 days; HR:0.49, 95% CI 0.29-0.83; p=0.007). RDR with PARP inhibitors are frequent, particularly in germline BRCA1/2 mutation carriers. These findings have clinical implications for patient outcomes and may reflect underlying intrapatient genomic heterogeneity.

Clinical outcomes and prognostic factors of patients with advanced mesothelioma treated in a phase I clinical trials unit

BACKGROUND

We have previously reported a prognostic score for patients in phase I trials in the Drug Development Unit, treated at the Royal Marsden Hospital (RPS). The RPS is an objective tool used in patient selection for phase I trials based on albumin, number of disease sites and LDH. Patients with mesothelioma are often selected for phase I trials as the disease remains localised for long periods of time. We have now reviewed the clinical outcomes of patients with relapsed malignant mesothelioma (MM) and propose a specific mesothelioma prognostic score (m-RPS) that can help identify patients who are most likely to benefit from early referral.

METHODS

Patients who participated in 38 phase I trials between September 2003 and November 2015 were included in the analysis. Efficacy was assessed by response rate, median overall survival (OS) and progression-free survival (PFS). Univariate (UVA) and multivariate analyses (MVA) were carried out to develop the m-RPS.

RESULTS

A total of 65 patients with advanced MM were included in this retrospective study. The PFS was 2.5 months (95% confidence interval [CI] 2.0-3.1 months) and OS was 8 months (95% CI 5.6-9.8 months). A total of four (6%) patients had RECIST partial responses, whereas 26 (40%) patients had RECIST stable disease >3 months. The m-RPS was developed comprising of three different prognostic factors: a neutrophil: lymphocyte ratio greater than 3, the presence of more than two disease sites (including lymph nodes as a single site of disease) and albumin levels less than 35 from the MVA. Patients each received a score of 1 for the presence of each factor. Patients in group A (m-RPS 0-1; n = 35) had a median OS of 13.4 months (95% CI 8.5-21.6), whereas those in group B (m-RPS 2-3; n = 30) had a median OS of 4.0 months (95% CI 2.9-7.1, P < 0.0001). A total of 56 (86%) patients experienced G1-2 toxicities, whereas reversible G3-4 toxicities were observed in 18 (28%) patients. Only 10 (15%) patients discontinued phase I trials due to toxicity.

CONCLUSIONS

Phase I clinical trial therapies were well tolerated with early signals of antitumour activity in advanced MM patients. The m-RPS is a useful tool to assess MM patient suitability for phase I trials and should now be prospectively validated.

Precision Medicine for Molecularly Targeted Agents and Immunotherapies in Early-Phase Clinical Trials

Precision medicine in oncology promises the matching of genomic, molecular, and clinical data with underlying mechanisms of a range of novel anticancer therapeutics to develop more rational and effective antitumor strategies in a timely manner. However, despite the remarkable progress made in the understanding of novel drivers of different oncogenic processes, success rates for the approval of oncology drugs remain low with substantial fiscal consequences. In this article, we focus on how recent rapid innovations in technology have brought greater clarity to the biological and clinical complexities of different cancers and advanced the development of molecularly targeted agents and immunotherapies in clinical trials. We discuss the key challenges of identifying and validating predictive biomarkers of response and resistance using both tumor and surrogate tissues, as well as the hurdles associated with intratumor heterogeneity. Finally, we outline evolving strategies employed in early-phase trial designs that incorporate omics-based technologies.

Serial Next-Generation Sequencing of Circulating Cell-Free DNA Evaluating Tumor Clone Response To Molecularly Targeted Drug Administration

PURPOSE

We evaluated whether next-generation sequencing (NGS) of circulating cell-free DNA (cfDNA) could be used for patient selection and as a tumor clone response biomarker in patients with advanced cancers participating in early-phase clinical trials of targeted drugs.

EXPERIMENTAL DESIGN

Plasma samples from patients with known tumor mutations who completed at least two courses of investigational targeted therapy were collected monthly, until disease progression. NGS was performed sequentially on the Ion Torrent PGM platform.

RESULTS

cfDNA was extracted from 39 patients with various tumor types. Treatments administered targeted mainly the PI3K-AKT-mTOR pathway (n = 28) or MEK (n = 7). Overall, 159 plasma samples were sequenced with a mean sequencing coverage achieved of 1,685X across experiments. At trial initiation (C1D1), 23 of 39 (59%) patients had at least one mutation identified in cfDNA (mean 2, range 1-5). Out of the 44 mutations identified at C1D1, TP53, PIK3CA and KRAS were the top 3 mutated genes identified, with 18 (41%), 9 (20%), 8 (18%) different mutations, respectively. Out of these 23 patients, 13 received a targeted drug matching their tumor profile. For the 23 patients with cfDNA mutation at C1D1, the monitoring of mutation allele frequency (AF) in consecutive plasma samples during treatment with targeted drugs demonstrated potential treatment associated clonal responses. Longitudinal monitoring of cfDNA samples with multiple mutations indicated the presence of separate clones behaving discordantly. Molecular changes at cfDNA mutation level were associated with time to disease progression by RECIST criteria.

CONCLUSIONS

Targeted NGS of cfDNA has potential clinical utility to monitor the delivery of targeted therapies.

Strategies for modern biomarker and drug development in oncology

Technological advancements in the molecular characterization of cancers have enabled researchers to identify an increasing number of key molecular drivers of cancer progression. These discoveries have led to multiple novel anticancer therapeutics, and clinical benefit in selected patient populations. Despite this, the identification of clinically relevant predictive biomarkers of response continues to lag behind. In this review, we discuss strategies for the molecular characterization of cancers and the importance of biomarkers for the development of novel antitumor therapeutics. We also review critical successes and failures in oncology, and detail the lessons learnt, which may aid in the acceleration of anticancer drug development and biomarker discovery.

Current questions for the treatment of advanced gastric cancer

BACKGROUND

Gastric cancer remains a major health problem worldwide. Treatment of advanced gastric cancer is controversial and there is no standard regimen for first- or second-line chemotherapy (CT). This review aims to give an overview of the hot topics concerning treatment, prognostic factors and new strategies in advanced gastric cancer.

MATERIAL AND METHODS

Seven questions of special clinical interest have been formulated previously to the literature review. With the aim of answering each of these questions, a specific search of the relevant trials and meta-analyses published or communicated from 1990 to date was performed.

RESULTS

Patients treated with CT have a survival benefit over those treated with only best supportive care (BSC). Such active cytotoxic drugs as cisplatin or docetaxel and targeted agents as trastuzumab showed superiority in randomized trials. Other agents such as oxaliplatin, oral fluoropyrimidines and irinotecan showed non-inferiority or less toxic results, positioning them as valuable alternatives to classical schedules. Combination regimens seem to be an improvement over single agent therapy. However, increased toxicity of some regimens makes their general use difficult. Second-line CT is of value for selected patients with good performance status. Trastuzumab is the only targeted agent showing better survival when added to chemotherapy in HER2-driven tumors.

CONCLUSIONS

With the introduction of new agents, management of advanced gastric cancer has experienced important changes. First and second-line CT improve survival in patients with good performance status. Future trials should address how to better select patients for new, targeted agents, based upon validated predictive biomarkers.

PCR analysis of immunoglobulin heavy chain (IgH) and TcR-gamma chain gene rearrangements in the diagnosis of lymphoproliferative disorders: results of a study of 525 cases

This report summarizes a cumulative 4-year experience in polymerase chain reaction (PCR) analysis of immunoglobin heavy chain (IgH) and TcR-gamma chain gene rearrangements in 525 cases of lymphoproliferative disorders. Because the sensitivity of the PCR methodology was found to be tissue dependent, in the study of the presence of clonal cell population in tissues containing a small number of polyclonal lymphocytes, such as skin and gastrointestinal biopsy specimens, we used the multiple-PCR run approach. In this latter methodology, we repeat the PCR reaction from the same sample at least three times to confirm the reproducibility of the results. In the study of 273 cases of B- or T-cell lymphomas with characteristic immunomorphological and clinical features, a clonal IgH or TcR-gamma chain gene rearrangement was detected in approximately 80% of cases. A clonal rearrangement involving both IgH and TcR-gamma chain genes was found in 10% of cases of both B-cell and T-cell lymphomas. The study of 167 cases of nonneoplastic lymphoid tissue samples showed the presence of clonally rearranged cell populations for IgH or TcR-gamma genes in 3 and 9% of cases, respectively. We also applied PCR for the study of 85 cases of lymphoproliferations with no definite diagnosis (i.e., benign versus malignant) after immunomorphological analysis. In 65 cases (76%), the correlation of immunomorphological features with the presence (48 cases) or the absence (17 cases) of clonal lymphoid cell populations led to a definite diagnosis. In almost all these cases, the final diagnosis was found to be in agreement with the clinical course. In the 20 remaining cases (24%), no definite diagnosis could be made. We also assessed the value of PCR in detecting bcl-2/J(H) gene rearrangement as an additional clonal marker in the diagnosis of follicular lymphoma. Bcl-2/J(H) rearrangement and/or IgH gene rearrangement was found in approximately 85% (71/85) of follicular lymphoma cases studied.

[Detection of residual disease in follicular lymphomas using the PCR technique: importance of clono-specific probes]

Follicular lymphoma constitutes 30-40% of non-Hodgkin's lymphomas. Most patients have widespread disease at diagnosis. The clinical course is generally indolent, and it is not usually curable with available treatment. The source of relapse in patients who achieve complete clinical remission is residual neoplastic cells that are present below the limits of detection using standard techniques. With the development of PCR technology, the presence of these residual malignant cells [Minimal Residual Disease (MRD)] has been demonstrated clearly. Recently, an association of high-dose chemotherapy with autologous bone marrow or peripheral blood progenitor cell autograft appeared promising in the treatment of these lymphomas. In the search of clonal markers for the detection of MRD in follicular lymphomas, two strategies can be used. In the cases associated with the t(14;18) (q32;q21) chromosomal translocation, the bcl-2/JH junctional regions are amplified by PCR in approximately equal to 50% of cases and then sequenced in order to synthesize an anti-junction oligonucleotide probe specific for each patient's malignant clone (clonospecific probe). In the cases negative for this translocation, an alternative strategy consists in the amplification of immunoglobulin high chain (IgH) gene rearrangement (approximately equal to 75% of cases). The present review highlights the value of molecular markers such as bcl-2/JH and VH/JH rearrangements to follow the neoplastic clone and to detect MRD in patients with follicular lymphomas.