A phase II trial of the proteasome inhibitor bortezomib in patients with advanced biliary tract cancers

Bortezomib in previously treated phosphatase and tension homology-deficient patients with advanced intrahepatic cholangiocarcinoma: An open-label, prospective and single-centre phase II trial

INTRODUCTION

Intrahepatic cholangiocarcinoma (ICC) is characterized by a dismal prognosis with limited therapeutic alternatives. To explore phosphatase and tension homolog (PTEN) as a biomarker for proteasome inhibition in ICC, we conducted a phase II trial to assess the second-line efficacy of bortezomib in PTEN-deficient advanced ICC patients.

METHODS

A total of 130 patients with advanced ICC in our centre were screened by PTEN immunohistochemical staining between 1 July 2017, and 31 December 2021, and 16 patients were ultimately enrolled and treated with single-agent bortezomib 1.3 mg/m2 on days 1, 4, 8 and 11 of a 21-day cycle. The primary endpoint was the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors v1.1.

RESULTS

The median follow-up was 6.55 months (95% confidence interval [CI]: 0.7-19.9 months). Among the 16 enrolled patients, the ORR was 18.75% (3/16) and the disease control rate was 43.75% (7/16). The median progress-free survival was 2.95 months (95% CI: 2.1-5.1 months) and the median overall survival (mOS) was 7.2 months (95% CI: 0.7-21.6 months) in the intent-to-treat-patients. Treatment-related adverse events of any grade were reported in 16 patients, with thrombopenia being the most common toxicity. Patients with PTEN staining scores of 0 were more likely to benefit from bortezomib than those with staining scores > 0.

CONCLUSIONS

Bortezomib yielded an encouraging objective response and a favourable OS as a second-line agent in PTEN-deficient ICC patients. Our findings suggest bortezomib as a promising therapeutic option for patients with PTEN-deficient ICC.

HIGHLIGHTS

There is a limited strategy for the second-line option of intrahepatic cholangiocarcinoma (ICC). This investigator-initiated phase 2 study evaluated bortezomib in ICC patients with phosphatase and tension homology deficiency. The overall response rate was 18.75% and the overall survival was 7.2 months in the intent-to-treat cohort. These results justify further developing bortezomib in ICC patients with PTEN deficiency.

Organelle stress and alterations in interorganelle crosstalk during liver fibrosis

The synchronous functioning and quality control of organelles ensure cell survival and function and are essential for maintaining homeostasis. Prolonged exposure to stressors (viruses, bacteria, parasitic infections, alcohol, drugs) or genetic mutations often disrupt the functional integrity of organelles which plays a critical role in the initiation and progression of several diseases including chronic liver diseases. One of the most important pathologic consequences of chronic liver diseases is liver fibrosis, characterized by tissue scarring due to the progressive accumulation of extracellular matrix components. Left untreated, fibrosis may advance to life-threatening complications such as cirrhosis, hepatic decompensation, and HCC, which collectively accounts for ∼1 million deaths per year worldwide. Owing to the lack of treatment options that can regress or reverse cirrhosis, liver transplantation is currently the only available treatment for end-stage liver disease. However, the limited supply of usable donor organs, adverse effects of lifelong immunosuppressive regimes, and financial considerations pose major challenges and limit its application. Hence, effective therapeutic strategies are urgently needed. An improved understanding of the organelle-level regulation of fibrosis can help devise effective antifibrotic therapies focused on reducing organelle stress, limiting organelle damage, improving interorganelle crosstalk, and restoring organelle homeostasis; and could be a potential clinical option to avoid transplantation. This review provides a timely update on the recent findings and mechanisms covering organelle-specific dysfunctions in liver fibrosis, highlights how correction of organelle functions opens new treatment avenues and discusses the potential challenges to clinical application.

A combination therapy of bortezomib, CXCR4 inhibitor, and checkpoint inhibitor is effective in cholangiocarcinoma in vivo

Cholangiocarcinoma (CCA) is a biliary tree malignancy with a dismal prognosis. Tumor microenvironment (TME), including cancer-associated fibroblasts (CAFs) has been shown to be involved in drug resistance. To model the interactions between cancer cells and the TME, we established CCA complex patient-derived organoids (cPDOs) to include epithelial PDO (ePDOs) and matched CAFs. While ePDOs were sensitive to bortezomib, we found the matched cPDOs were relatively resistant. Mechanistically, this resistance was correlated with over-expression of CXCR4 in the CAF component of cPDOs. In accord with the role of CXCR4 in the resistance to bortezomib, we found that a CXCR4 inhibitor can reverse the resistance to bortezomib in vivo. Furthermore, we found that the inhibition of CXCR4 allowed bortezomib to sensitize CCA to anti-PD1 treatment, with a significant reduction of tumor burden and long-term overall survival. This novel cancer/stroma/immune triple treatment holds great promise for the treatment of CCA.

MLN2238 exerts its anti-tumor effects via regulating ROS/JNK/mitochondrial signaling pathways in intrahepatic cholangiocarcinoma

Background: Intrahepatic Cholangiocarcinoma (iCCA) is a highly malignant tumor with limited treatment options that contributes largely to cancer-related deaths worldwide. Compared with traditional transcriptomic analysis, single-cell RNA sequencing (scRNA-seq) is emerging as a more advanced and popular tool for the in-depth exploration of cellular diversity and molecular complexity. As a next-generation proteasome inhibitor, MLN2238 presents better pharmacodynamics, pharmacokinetics, and therapeutic responses in various cancers. However, its effects and mechanisms of action in iCCA remain unknown. Methods: iCCA tumor heterogeneity was determined based on 4,239 qualified scRNA-seq data from 10 iCCA samples. The potential biological roles of proteasome-related genes in iCCA were investigated using a pseudo-trajectory reconstruction. The effect of MLN2238 on iCCA cell proliferation was estimated using the CCK-8, EdU, and clone formation assays. Flow cytometry was used to examine the effect of added MLN2238 on cell cycle and apoptosis levels. Autophagic flux was detected using AdPlus-mCherry-GFP-LC3B cells. ROS levels and mitochondrial membrane potential were determined using DCFH-DA probing and JC-1 staining. JNK activation and mitochondrial apoptosis were observed using western blotting and immunofluorescence microscopy, respectively. Finally, we used a tumor-bearing mouse model to validate its efficacy in vivo for iCCA treatment. Results: Proteasome-related genes were dysregulated in iCCA progression and expressed at higher levels in tumor tissues. MLN2238 suppressed cell proliferation, blocked the cell cycle in the G2/M phase, promoted apoptosis, and induced cytoprotective autophagy in iCCA cells. Furthermore, MLN2238 increased ROS levels and activated the JNK signaling pathway. Inhibition of ROS and JNK activation by NAC and SP600125 significantly reversed MLN2238-induced apoptosis. MLN2238 also suppressed the growth of iCCA tumors in vivo. Conclusion: Proteasome-related genes play pivotal roles in iCCA development. MLN2238, as a proteasome inhibitor, induces apoptosis in iCCA cells through ROS/JNK/mitochondrial signaling pathways, and hence, making MLN2238 a potential therapeutic choice for iCCA.

PTEN status determines chemosensitivity to proteasome inhibition in cholangiocarcinoma

Patient-derived xenografts (PDXs) and PDX-derived cells (PDCs) are useful in preclinical research. We performed a drug screening assay using PDCs and identified proteasome inhibitors as promising drugs for cholangiocarcinoma (CCA) treatment. Furthermore, we determined that phosphate and tensin homology deleted on chromosome ten (PTEN) deficiency promotes protein synthesis and proteasome subunit expression and proteolytic activity, creating a dependency on the proteasome for cancer cell growth and survival. Thus, targeting the proteasome machinery with the inhibitor bortezomib inhibited the proliferation and survival of CCA cells lacking functional PTEN. Therapeutic evaluation of PDXs, autochthonous mouse models, and patients confirmed this dependency on the proteasome. Mechanistically, we found that PTEN promoted the nuclear translocation of FOXO1, resulting in the increased expression of BACH1 and MAFF BACH1 and MAFF are transcriptional regulators that recognize the antioxidant response element, which is present in genes encoding proteasome subunits. PTEN induced the accumulation and nuclear translocation of these proteins, which directly repressed the transcription of genes encoding proteasome subunits. We revealed that the PTEN-proteasome axis is a potential target for therapy in PTEN-deficient CCA and other PTEN-deficient cancers.

Molecular Landscape and Therapeutic Strategies in Cholangiocarcinoma: An Integrated Translational Approach towards Precision Medicine

Cholangiocarcinomas (CCAs) are heterogeneous biliary tract malignancies with dismal prognosis, mainly due to tumor aggressiveness, late diagnosis, and poor response to current therapeutic options. High-throughput technologies have been used as a fundamental tool in unveiling CCA molecular landscape, and several molecular classifications have been proposed, leading to various targeted therapy trials. In this review, we aim to analyze the critical issues concerning the status of precision medicine in CCA, discussing molecular signatures and clusters, related to both anatomical classification and different etiopathogenesis, and the latest therapeutic strategies. Furthermore, we propose an integrated approach comprising the CCA molecular mechanism, pathobiology, clinical and histological findings, and treatment perspectives for the ultimate purpose of improving the methods of patient allocations in clinical trials and the response to personalized therapies.

Will advanced cholangiocarcinoma become a targetable malignancy?

Cholangiocarcinoma and biliary tract cancers are rare but aggressive tumors that are characterized by an heterogenous molecular and genetic footprint. Genetic aberrations such as FGFR2 fusion and ErBb2 amplification are common in those cancers. Recent studies aimed at exploring the efficacy and benefit of targeted therapy in the treatment of advanced cholangiocarcinoma. Many promising drugs exist and warrant additional investigations. This review will summarize available results and highlight therapeutic strategies incorporated in clinical trials.

PTEN deficiency facilitates the therapeutic vulnerability to proteasome inhibitor bortezomib in gallbladder cancer

Gallbladder cancer (GBC) is an aggressive malignancy of biliary tract with poor prognosis. Although several studies have shown the frequency of relevant genetic alterations, there are few genetic models or translational studies that really benefit for GBC treatment in the era of precision medicine. By targeted sequencing and immunohistochemistry staining, we identified that phosphate and tension homology deleted on chromosome ten (PTEN) was frequently altered in GBC specimens, and loss of PTEN expression was independently correlated with poor survival outcomes. Further drug screening assays revealed proteasome inhibitor bortezomib as a promising agent for GBC treatment, and knockdown of PTEN increased bortezomib efficacy both in vivo and in vitro. Therapeutic evaluation of patient derived xenografts (PDXs) strongly supported the utilization of bortezomib in PTEN deficient GBC. Mechanically, functional PTEN inhibited ARE-dependent transcriptional activity, the same machinery regulating the transcription of proteasome subunits, thus PTEN suppressed proteasome activity and bortezomib sensitivity. Through siRNA screening, we identified the ARE-related transcriptional suppressor BACH1 involved in PTEN-mediated proteasome inhibition and regulated by PTEN-AKT1 axis. In summary, our study indicates that proteasome activity represents a prime therapeutic target in PTEN-deficient GBC tumors, which is worthy of further clinical validation.

Broadening the therapeutic horizon of advanced biliary tract cancer through molecular characterisation

Biliary tract cancers (BTC) comprise a group of rare and heterogeneous poor-prognosis tumours with the incidence of intrahepatic cholangiocarcinoma increasing over recent years. Combination chemotherapy with gemcitabine and cisplatin is the established first-line treatment for advanced BTC with a significant but modest survival advantage over monotherapy. There remains no accepted standard treatment in the second-line setting, although recent results from a randomised study have shown a survival benefit with 5-fluorouracil and oxaliplatin chemotherapy. Historically, clinical trials investigating targeted therapies in unselected BTC have failed to demonstrate significant clinical benefit. More recently, advancement in molecular exploration of BTC has shed light on the complex biological heterogeneity within these tumours and has also identified actionable genomic aberrations, such as fibroblast growth factor receptor 2 (FGFR2) gene fusions, isocitrate dehydrogenase (IDH) and BRAF mutations, which offer promise with the anticipation of increased responses and durable clinical benefit in selected patients. Several targeted drugs have now entered clinical development with some encouraging results being seen. Here we review the current and rapidly evolving therapeutic landscape of advanced BTC, including targeted therapies and immunotherapy. We also discuss how recent efforts and successes in BTC are overcoming the obstacles typically associated with precision medicine in rare cancers. Ultimately, the management of advanced BTC is likely to become molecularly selected in the near future with the hope of finally improving the bleak prognosis of patients with this disease.

Targeted Therapies in Trial for Non-Resectable Gallbladder Cancer

PURPOSE

Gallbladder cancer (GBC) is the most common malignancy of the biliary tract. The median survival of the disease is around 6 months. In this study, we explore clinical trials related to non-resectable GBC, determine the shortcomings leading to the lack of development of new treatment, and shed light on possible areas of improvement.

METHODS

On April 20, 2019 the authors completed a search on ClinicalTrials.gov for all therapeutic and interventional clinical trials involving non-resectable GBC, without any limits on date or location. Trial characteristics such as duration, phase, sample size, and whether a publication was produced were collected and analyzed.

RESULTS

Sixty-two trials met our selection criteria. The average duration of trials was 5 years. Trials were conducted in 8 different countries: most of them in North America (USA and Canada). About 88% of trials were in early phases (I, I/II, and II) and 85% of trials were completed. Only 4 relevant publications were produced from all the trials in our study. Gemcitabine was the most common drug used. Use of gemcitabine alone or in combination with either capecitabine or cisplatin showed significant increase mean progression-free survival.

CONCLUSION

This study revealed a low number of trials, lack of geographic diversity, and scarcity of publications concerning non-resectable GBC. Adequate management of is of great importance to reach effective therapies for this disease.

Loss of BAP1 expression is associated with genetic mutation and can predict outcomes in gallbladder cancer

Background

BRCA-1 associated protein (BAP1) is a de-ubiquitinating enzyme that regulates gene expression. Recently, the BAP1 mutation and its involvement in cancer survival have been reported in a range of tumor types, including uveal melanoma, mesothelioma, renal cancers, and biliary tract cancers. However, the frequency of BAP1 mutation and down-regulation varies among tumor types, and little is known about the function of BAP1 silencing in cancer cells. Gallbladder carcinoma (GBC) is a type of biliary tract cancer with a poor prognosis. Few mutational studies have investigated the role of BAP1 in GBC, and no functional study in vitro-, or clinical studies about cancer survival have been done.

Methods

GBC cells were studied by following the small interfering RNA mediated silencing of BAP1 with regard to proliferation, migration, invasion, and drug sensitivity. We carried out genomic, epigenomic and immunohistochemical analyses to detect somatic BAP1 alterations in 47 GBC patients undergoing surgical resection.

Results

BAP1 depletion resulted in increased migration and invasion, but not proliferation, and also resulted in decreased sensitivity to bortezomib, a proteasome inhibitor. Suppressed expression of BAP1 occurred in 22 GBC cases (46.8%) and showed a strong trend toward a worse median survival time of 13.3 months (95% CI, 17.6–62.6) (p = 0.0034). Sanger sequencing revealed a loss-of-function mutation of BAP1 in 11 out of these 22 GBC cases (50%) with low BAP1 expression, whereas 2 out of 25 GBC cases (8%) were detected in cases with high BAP1 expression. Partial changes in methylation were observed in 6 out of 47 cases, but methylation did not show a strong relationship to BAP1 expression or to the prognosis.

Conclusion

Our findings showed that genetic mutations are involved in BAP1 down-regulation, leading to promotion of the invasive character of cancer cells and poor prognosis in GBC.

The landscape of targeted therapies for cholangiocarcinoma: current status and emerging targets

Cholangiocarcinoma (CCA) is a relatively rare malignancy that arises from the epithelial cells of the intrahepatic, perihilar and distal biliary tree. Intrahepatic CCA (ICC) represents the second most common primary liver cancer, after hepatocellular cancer. Two-thirds of the patients with ICC present with locally advanced or metastatic disease. Despite standard treatment with gemcitabine and cisplatin, prognosis remains dismal with a median survival of less than one year. Several biological plausibilities can account for its poor clinical outcomes. First, despite the advent of next generation and whole exome sequencing, no oncogenic addiction loops have been validated as clinically actionable targets. Second, the anatomical, pathological and molecular heterogeneity, and rarity of CCA confer an ongoing challenge of instituting adequately powered clinical trials. Last, most of the studies were not biomarker-driven, which may undermine the potential benefit of targeted therapy in distinct subpopulations carrying the unique molecular signature. Recent whole genome sequencing efforts have identified known mutations in genes such as epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), v-raf murine sarcoma viral oncogene homolog (BRAF) and tumor protein p53 (TP53), novel mutations in isocitrate dehydrogenase (IDH), BRCA1-Associated Protein 1 (BAP1) and AT-rich interactive domain-containing protein 1A (ARID1A), and novel fusions such as fibroblast growth factor receptor 2 (FGFR2) and ROS proto-oncogene 1 (ROS1). In this review, we will discuss the evolving genetic landscape of CCA, with an in depth focus on novel fusions (e.g. FGFR2 and ROS1) and somatic mutations (e.g. IDH1/2), which are promising actionable molecular targets.

Positioning of proteasome inhibitors in therapy of solid malignancies

Targeting of the protein degradation pathway, in particular, the ubiquitin-proteasome system, has emerged as an attractive novel cancer chemotherapeutic modality. Although proteasome inhibitors have been most successfully applied in the treatment of hematological malignancies, they also received continuing interest for the treatment of solid tumors. In this review, we summarize the current positioning of proteasome inhibitors in the treatment of common solid malignancies (e.g., lung, colon, pancreas, breast, and head and neck cancer), addressing topics of their mechanism(s) of action, predictive factors and molecular mechanisms of resistance.

Therapeutic options for intrahepatic cholangiocarcinoma

Biliary tract cancer (BTC) is a heterogeneous group of cancers, which is composed of intrahepatic cholangiocarcinoma (ICCA), extrahepatic cholangiocarcinoma (ECCA), gallbladder cancers and ampullary carcinomas. While all anatomic subgroups are treated uniformly, our understanding about the pathogenesis has allowed us to reason that each group represents a clinically and genetically diverse disease. The majority of patients present with locally advanced or metastatic disease, where the standard treatment is combination systemic cytotoxic chemotherapy with gemcitabine and cisplatin. While most receive a clinical benefit from chemotherapy, patients eventually progress where no standardized therapies are available in the refractory setting. With the use of next generation sequencing, we have come to understand that ICCA is a diverse genomic disease with many actionable alterations that may serve as potential therapeutic targets. Further studies investigating the role of novel targeted agents (as a single agent or with combination chemotherapy) will hopefully provide additional treatment options for this highly lethal disease.

New molecular and immunotherapeutic approaches in biliary cancer

Biliary tract carcinoma is a collective term for a group of rare gastrointestinal cancers. This overview outlines the key pathways and specialised therapeutics in biliary cancer and the emerging role of immunotherapy by highlighting the rationale and selected examples of studies in each area.

Novel investigational therapies for treating biliary tract carcinoma

INTRODUCTION

Cholangiocarcinoma (CCA) is an epithelial cell malignancy arising from bile ducts and/or peribiliary glands. Even though it is considered as a rare neoplasm, its incidence is raising, particularly in developed countries. Prognosis is generally poor with few patients who present the inclusion criteria for surgery (the mainstay treatment for this tumour). Several genetic alterations potentially driving tumour progression have been described, representing a possible target for new compounds. Areas covered: A clinical trial search in Clinicaltrials.gov encompassing a literature search in PubMed and ASCO/ESMO Websites was undertaken in March 2016. Expert opinion: Notwithstanding a large number of drug tested, results are still disappointing. The main reasons could be the low number of patients enrolled in trials, and the lack of a patient selection based on the biological profile of the tumours. Potential active drugs could have been discharged simply because beneficial in a particular subgroup of patients and not in un unselected population. The future direction of the research should consider biomarker evaluation in order to describe the genetic alteration/s that drive tumour progression and aggressiveness and the mechanisms of drug resistance. Finally, it will be of great interest to consider the results of immunotherapy whenever available.

Systemic therapy of cholangiocarcinoma: From chemotherapy to targeted therapies

Cholangiocarcinomas (CCA) are rare tumors of the liver with poor prognosis. The standard of care in patients with unresectable tumors or metastatic disease is combination chemotherapy (CT) with gemcitabine and cisplatin. Targeted therapies inhibiting EGFR, VEGF, MEK and others are broadly tested in CCA but to date, the existing data from randomized and nonrandomized trials do not justify the application of small molecules outside of clinical trials. In clinical practice, many patients receive second-line CT after failure of gemcitabine/cisplatin, although there is so far no evidence to support second-line CT. This review summarizes current chemotherapy protocols and ongoing studies, including conventional chemotherapy and targeted therapies.

Trial Watch: Proteasomal inhibitors for anticancer therapy

The so-called "ubiquitin-proteasome system" (UPS) is a multicomponent molecular apparatus that catalyzes the covalent attachment of several copies of the small protein ubiquitin to other proteins that are generally (but not always) destined to proteasomal degradation. This enzymatic cascade is crucial for the maintenance of intracellular protein homeostasis (both in physiological conditions and in the course of adaptive stress responses), and regulates a wide array of signaling pathways. In line with this notion, defects in the UPS have been associated with aging as well as with several pathological conditions including cardiac, neurodegenerative, and neoplastic disorders. As transformed cells often experience a constant state of stress (as a result of the hyperactivation of oncogenic signaling pathways and/or adverse microenvironmental conditions), their survival and proliferation are highly dependent on the integrity of the UPS. This rationale has driven an intense wave of preclinical and clinical investigation culminating in 2003 with the approval of the proteasomal inhibitor bortezomib by the US Food and Drug Administration for use in multiple myeloma patients. Another proteasomal inhibitor, carfilzomib, is now licensed by international regulatory agencies for use in multiple myeloma patients, and the approved indications for bortezomib have been extended to mantle cell lymphoma. This said, the clinical activity of bortezomib and carfilzomib is often limited by off-target effects, innate/acquired resistance, and the absence of validated predictive biomarkers. Moreover, the antineoplastic activity of proteasome inhibitors against solid tumors is poor. In this Trial Watch we discuss the contribution of the UPS to oncogenesis and tumor progression and summarize the design and/or results of recent clinical studies evaluating the therapeutic profile of proteasome inhibitors in cancer patients.