Biomarker-driven trial in metastatic pancreas cancer: feasibility in a multicenter study of saracatinib, an oral Src inhibitor, in previously treated pancreatic cancer

Recent progress in SRC targeted therapy for pancreatic cancer

Pancreatic cancer (PC) is a highly lethal malignancy with a 5-year survival rate of only 10% and is extremely resistant to chemotherapy. Therefore, developing effective therapeutic drugs is urgently needed. SRC is a proto-oncogenic tyrosine protein kinase and highly expressed in more than 70% of PCs. SRC is involved in regulating the proliferation, infiltration, and metastasis of PC cells as well as tumor angiogenesis, thus representing one of the most promising molecular targets for developing novel drugs. Preclinical studies demonstrate that small-molecule SRC inhibitors display significant anti-cancer activities in vitro and in vivo, and have a synergistic effect with conventional chemotherapy drugs against PC. Some SRC inhibitors have been evaluated in clinical trials. This article analyzes the regulatory mechanism of SRC and the recent progress and problems in developing drugs targeting SRC for the treatment of PC. Unfortunately, up to date no SRC inhibitor or regiment containing SRC inhibitors has been approved for the clinical treatment of PC. In the authors' opinion, the introduction of precision medicine principles to carry out SRC inhibitor clinical trials, combination of immunotherapy and SRC inhibitors, seeking more selective and effective SRC inhibitors, and further exploration of the SRC regulatory network may be the future directions for developing SRC-targeted therapies against PC.

Identification of lymphocyte cell-specific protein-tyrosine kinase (LCK) as a driver for invasion and migration of oral cancer by tumor heterogeneity exploitation

BACKGROUND

Cancer metastases are the main cause of lethality. The five-year survival rate for patients diagnosed with advanced stage oral cancer is 30%. Hence, the identification of novel therapeutic targets is an urgent need. However, tumors are comprised of a heterogeneous collection of cells with distinct genetic and molecular profiles that can differentially promote metastasis making therapy development a challenging task. Here, we leveraged intratumoral heterogeneity in order to identify drivers of cancer cell motility that might be druggable targets for anti-metastasis therapy.

METHODS

We used 2D migration and 3D matrigel-based invasion assays to characterize the invasive heterogeneity among and within four human oral cancer cell lines in vitro. Subsequently, we applied mRNA-sequencing to map the transcriptomes of poorly and strongly invasive subclones as well as primary tumors and matched metastasis.

RESULTS

We identified SAS cells as a highly invasive oral cancer cell line. Clonal analysis of SAS yielded a panel of 20 subclones with different invasive capacities. Integrative gene expression analysis identified the Lymphocyte cell-specific protein-tyrosine kinase (LCK) as a druggable target gene associated with cancer cell invasion and metastasis. Inhibition of LCK using A-770041 or dasatinib blocked invasion of highly aggressive SAS cells. Interestingly, reduction of LCK activity increased the formation of adherens junctions and induced cell differentiation.

CONCLUSION

Analysis of invasive heterogeneity led to the discovery of LCK as an important regulator of motility in oral cancer cells. Hence, small molecule mediated inhibition of LCK could be a promising anti-metastasis therapy option for oral cancer patients.

Proteomic Analysis of Src Family Kinase Phosphorylation States in Cancer Cells Suggests Deregulation of the Unique Domain

The Src family kinases (SFK) are homologs of retroviral oncogenes, earning them the label of proto-oncogenes. Their functions are influenced by positive and negative regulatory tyrosine phosphorylation events and inhibitory and activating intramolecular and extramolecular interactions. This regulation is disrupted in their viral oncogene counterparts. However, in contrast to most other proto-oncogenes, the genetic alteration of these genes does not seem to occur in human tumors and how and whether their functions are altered in human cancers remain to be determined. To look for proteomic-level alterations, we took a more granular look at the activation states of SFKs based on their two known regulatory tyrosine phosphorylations, but found no significant differences in their activity states when comparing immortalized epithelial cells with cancer cells. SFKs are known to have other less well-studied phosphorylations, particularly within their unstructured N-terminal unique domains (UD), although their role in cancers has not been explored. In comparing panels of epithelial cells with cancer cells, we found a decrease in S17 phosphorylation in the UD of Src in cancer cells. Dephosphorylated S17 favors the dimerization of Src that is mediated through the UD and suggests increased Src dimerization in cancers. These data highlight the important role of the UD of Src and suggest that a deeper understanding of proteomic-level alterations of the unstructured UD of SFKs may provide considerable insights into how SFKs are deregulated in cancers. IMPLICATIONS: This work highlights the role of the N-terminal UD of Src kinases in regulating their signaling functions and possibly in their deregulation in human cancers.

LRRC19-A Bridge between Selenium Adjuvant Therapy and Renal Clear Cell Carcinoma: A Study Based on Datamining

Kidney renal clear cell carcinoma (KIRC) is the most common and fatal subtype of renal cancer. Antagonistic associations between selenium and cancer have been reported in previous studies. Selenium compounds, as anti-cancer agents, have been reported and approved for clinical trials. The main active form of selenium in selenoproteins is selenocysteine (Sec). The process of Sec biosynthesis and incorporation into selenoproteins plays a significant role in biological processes, including anti-carcinogenesis. However, a comprehensive selenoprotein mRNA analysis in KIRC remains absent. In the present study, we examined all 25 selenoproteins and identified key selenoproteins, glutathione peroxidase 3 (GPX3) and type 1 iodothyronine deiodinase (DIO1), with the associated prognostic biomarker leucine-rich repeat containing 19 (LRRC19) in clear cell renal cell carcinoma cases from The Cancer Genome Atlas (TCGA) database. We performed validations for the key gene expression levels by two individual clear cell renal cell carcinoma cohorts, GSE781 and GSE6344, datasets from the Gene Expression Omnibus (GEO) database. Multivariate survival analysis demonstrated that low expression of LRRC19 was an independent risk factor for OS. Gene set enrichment analysis (GSEA) identified tyrosine metabolism, metabolic pathways, peroxisome, and fatty acid degradation as differentially enriched with the high LRRC19 expression in KIRC cases, which are involved in selenium therapy of clear cell renal cell carcinoma. In conclusion, low expression of LRRC19 was identified as an independent risk factor, which will advance our understanding concerning the selenium adjuvant therapy of clear cell renal cell carcinoma.

A phase I study of gemcitabine + dasatinib (gd) or gemcitabine + dasatinib + cetuximab (GDC) in refractory solid tumors

PURPOSE

This study was conducted to define the maximum tolerated dose (MTD), recommended phase two dose (RPTD), and toxicities of gemcitabine + dasatinib (GD) and gemcitabine + dasatinib + cetuximab (GDC) in advanced solid tumor patients.

METHODS

This study was a standard phase I 3 + 3 dose escalation study evaluating two combination regimens, GD and GDC. Patients with advanced solid tumors were enrolled in cohorts of 3-6 to either GD or GDC. Gemcitabine was dosed at 1000 mg/m² weekly for 3 of 4 weeks, dasatinib was dosed in mg PO BID, and cetuximab was dosed at 250 mg/m² weekly after a loading dose of cetuximab of 400 mg/m². There were two dose levels for dasatinib: (1) gemcitabine + dasatinib 50 mg ± cetuximab, and (2) gemcitabine + dasatinib 70 mg ± cetuximab. Cycle length was 28 days. Standard cycle 1 dose-limiting toxicity (DLT) definitions were used. Eligible patients had advanced solid tumors, adequate organ and marrow function, and no co-morbidities that would increase the risk of toxicity. Serum, plasma, and skin biopsy biomarkers were obtained pre- and on-treatment.

RESULTS

Twenty-five patients were enrolled, including 21 with pancreatic adenocarcinoma. Three patients received prior gemcitabine. Twenty-one patients were evaluable for toxicity and 16 for response. Four DLTs were observed: Grade (Gr) 3 neutropenia (GDC1, n = 1), Gr 3 ALT (GD2, n = 2), and Gr 5 pneumonitis (GDC2, n = 1). Possible treatment-emergent adverse events (TEAEs) in later cycles included: Gr 3-4 neutropenia (n = 7), Gr 4 colitis (n = 1), Gr 3 bilirubin (n = 2), Gr 3 anemia (n = 2), Gr 3 thrombocytopenia (n = 2), Gr 3 edema/fluid retention (n = 1), and Gr 3 vomiting (n = 3). Six of 16 patients (3 of whom were gemcitabine-refractory) had stable disease (SD) as best response, median duration = 5 months (range 1-7). One gemcitabine-refractory patient had a partial response (PR). Median PFS was 2.9 months (95% CI 2.1, 5.8). Median OS was 5.8 months (95% CI 4.1, 11.8). Dermal wound biopsies demonstrated that dasatinib resulted in a decrease of total and phospho-Src levels, and cetuximab resulted in a decrease of EGFR and ERBB2 levels.

CONCLUSIONS

The MTD/RPTD of GD is gemcitabine 1000 mg/m² weekly for 3 of 4 weeks and dasatinib 50 mg PO BID. The clinical activity of GD seen in this study was modest, and does not support its further investigation in pancreatic cancer.

Current status and dilemma of second-line treatment in advanced pancreatic cancer: is there a silver lining?

Pancreatic cancer remains one of the most lethal malignant diseases worldwide. The majority of patients present with advanced disease and, therefore, need palliative chemotherapy. Some chemotherapeutic regimens have been well established as first-line therapies and have been shown to increase survival; however, almost all patients with advanced pancreatic cancer will experience disease progression after first-line therapy. Nevertheless, many patients who retain good performance status after initial treatment remain good candidates for additional therapy. Historically, few studies have assessed second-line therapy, with most reports representing small phase II trials with variable findings; however, clinical research for second-line treatment has increased in the past decade, and several randomized controlled trials using different regimens have been published. The current literature shows varying results on treatment efficacy and tolerability. Thus, we reviewed the published data on the use of chemotherapy in the second-line setting for the treatment of advanced pancreatic cancer.

Phase II clinical trials on investigational drugs for the treatment of pancreatic cancers

INTRODUCTION

Despite some recent advances in treatment options, pancreatic cancer remains a devastating disease with poor outcomes. In a trend contrary to most malignancies, both incidence and mortality continue to rise due to pancreatic cancer. The majority of patients present with advanced disease and there are no treatment options for this stage that have demonstrated a median survival > 1 year. As the penultimate step prior to Phase III studies involving hundreds of patients, Phase II clinical trials provide an early opportunity to evaluate the efficacy of new treatments that are desperately needed for this disease.

AREAS COVERED

This review covers the results of published Phase II clinical trials in advanced pancreatic adenocarcinoma published within the past 5 years. The treatment results are framed in the context of the current standards of care and the historic challenge of predicting Phase III success from Phase II trial results.

EXPERT OPINION

Promising therapies remain elusive in pancreatic cancer based on recent Phase II clinical trial results. Optimization and standardization of clinical trial design in the Phase II setting, with consistent incorporation of biomarkers, is needed to more accurately identify promising therapies that warrant Phase III evaluation.

[Multimodal treatment of pancreatic cancer]

Adenocarcinoma of the exocrine pancreas is one of the most aggressive types of solid tumor and stands at fourth position in the tumor death frequency scale due to a high mortality rate. Effective screening methods are not available and only radical surgery offers a curative option. With adjuvant chemotherapy the median survival time can be prolonged up to 23 months and approximately 25 % of patients are still alive after 5 years. Of these patients approximately 75-80 % are already in a palliative therapy situation at the time of diagnosis. In the last 5 years treatment options have been increased by the introduction of new chemotherapeutic drugs. For patients with metastasized disease median survival times of 6-12 months can currently be achieved depending on the general performance status at diagnosis but less than 5 % of these patients are still alive after 5 years. Neoadjuvant treatment strategies, radiation and immunotherapy do not play a role in evidence-based clinical practice. Despite progress in the understanding of cancer biology and new treatment options, non-resectable adenocarcinoma of the pancreas remains a disease with a very poor prognosis.

Toward a drug development path that targets metastatic progression in osteosarcoma

Despite successful primary tumor treatment, the development of pulmonary metastasis continues to be the most common cause of mortality in patients with osteosarcoma. A conventional drug development path requiring drugs to induce regression of established lesions has not led to improvements for patients with osteosarcoma in more than 30 years. On the basis of our growing understanding of metastasis biology, it is now reasonable and essential that we focus on developing therapeutics that target metastatic progression. To advance this agenda, a meeting of key opinion leaders and experts in the metastasis and osteosarcoma communities was convened in Bethesda, Maryland. The goal of this meeting was to provide a "Perspective" that would establish a preclinical translational path that could support the early evaluation of potential therapeutic agents that uniquely target the metastatic phenotype. Although focused on osteosarcoma, the need for this perspective is shared among many cancer types. The consensus achieved from the meeting included the following: the biology of metastatic progression is associated with metastasis-specific targets/processes that may not influence grossly detectable lesions; targeting of metastasis-specific processes is feasible; rigorous preclinical data are needed to support translation of metastasis-specific agents into human trials where regression of measurable disease is not an expected outcome; preclinical data should include an understanding of mechanism of action, validation of pharmacodynamic markers of effective exposure and response, the use of several murine models of effectiveness, and where feasible the inclusion of the dog with naturally occurring osteosarcoma to define the activity of new drugs in the micrometastatic disease setting.