A clinical update on the role of carfilzomib in the treatment of relapsed or refractory multiple myeloma

Bortezomib in cancer therapy: Mechanisms, side effects, and future proteasome inhibitors

The ubiquitin-proteasome pathway (UPP) regulates protein stability and normal cellular functions with the help of autocatalytic proteasome complex. Studies have linked aberrant proteasome activity to malignant cells and found that proteasome inhibitors play a significant role as therapeutic drugs for various types of cancer, specifically multiple myeloma and mantle cell lymphoma. Bortezomib, the first FDA-approved proteasome inhibitor for treating different stages of multiple myeloma, acts on cancer cells by inhibiting the 26S proteasome, modulating NF-κB, phosphorylating Bcl-2, upregulating of NOXA, blocking p53 degradation, activating caspase, generating reactive oxygen species (ROS), and inhibiting angiogenesis. However, its efficacy is limited due to side effects such as peripheral neuropathy (PN), thrombotic microangiopathy (TMA), and acute interstitial nephritis (AIN). Therefore, a better understanding of its precise mechanism of action may help mitigate these side effects. In this review, we have discussed the proposed mechanisms of action and off target effects of Bortezomib, along with the prospects of next generation potential proteasome inhibitor drugs in the treatment of cancer.

Brain-Permeable Immunoproteasome-Targeting Macrocyclic Peptide Epoxyketones for Alzheimer's Disease

Previously, we demonstrated that linear peptide epoxyketones targeting the immunoproteasome (iP) could ameliorate cognitive deficits in mouse models of Alzheimer's disease (AD) independently of amyloid deposition. We also reported the first iP-targeting macrocyclic peptide epoxyketones, which exhibit improved metabolic stability compared with their linear counterparts. Here, we prepared additional macrocyclic peptide epoxyketones and compared them with existing macrocyclic iP inhibitors by assessing Caco2 cell-based permeability and microsomal stability, providing the four best macrocyclic iP inhibitors. We then evaluated the four compounds using the Ames test and the potency assays in BV2 cells, selecting compound 5 as our AD drug lead. When 5 was administered intravenously (40 mg/kg) or orally (150 mg/kg) into healthy BALB/c mice, we observed considerable iP inhibition in the mouse brain, indicating good blood-brain barrier permeability and target engagement. Combined results suggest that 5 is a promising AD drug lead that may need further investigation.

Recent findings regarding the synergistic effects of emodin and its analogs with other bioactive compounds: Insights into new mechanisms

CONTEXT

Emodin is a natural bioactive ingredient mainly extracted from traditional Chinese herbs. Increasing lines of evidence suggest that emodin and its analogs exert notable synergistic pharmacological effects with other bioactive compounds.

OBJECTIVE

This review provides an overview of the pharmacological activity of emodin and its analogs in combination with other physiologically active substances, describes the related molecular mechanisms, and discusses future prospects in this field.

METHODS

Information from multiple scientific databases, such as PubMed, the China Knowledge Resource Integrated Database from the China National Knowledge Infrastructure (CNKI), the Web of Science, Google Scholar, and Baidu Scholar, was collected between January 2006 and August 2022. The subject terms used in the literature search were emodin, pharmaceutical activities, analogs, aloe emodin, rhein, and synergistic effects.

RESULTS

The comprehensive literature analysis suggested that combinations of emodin or its analogs with other bioactive compounds exert notable synergistic anticancer, anti-inflammatory, and antimicrobial effects and that such combinations improve glucose and lipid metabolism and central nervous system diseases.

DISCUSSION AND CONCLUSIONS

Further assessments of the dose-effect relationship and the differences in the efficacy of emodin or its analogs with other bioactive compounds among various modes of administration are needed, and a drug safety evaluation of these combinations needs to be carefully performed. Future studies should also focus on determining the optimal drug combinations for specific diseases.

Patients with Very High Risk of Cardiovascular Adverse Events during Carfilzomib Therapy: Prevention and Management of Events in a Single Center Experience

Carfilzomib (CFZ) improves the prognosis of multiple myeloma (MM) patients but has shown cardiovascular toxicity. The risk stratification of cardiovascular adverse events (CVAEs) now seems well established, while little is known about the course and management of patients with a high-cardiovascular-risk profile or experiencing CVAEs during therapy. Therefore, we aimed to describe our experience in decision making to support health professionals in selecting the best management strategies to prevent and treat CVAEs. A total of 194 patients with indication to CFZ underwent baseline evaluation of CVAEs risk and were prospectively followed. We propose a novel approach, which includes advanced cardiac imaging testing for patients at high baseline CV risk to rule out clinical conditions that could contraindicate starting CFZ. After baseline evaluation, 19 (9.8%) patients were found at high risk of CVAEs: 13 (6.7%) patients underwent advanced cardiac testing and 3 (1.5%) could not receive CFZ due to CV contraindications. A total of 178 (91.7%) patients started CFZ: 82 (46%) experienced arterial-hypertension-related events and 37 (20.8%) major CVAEs; 19 (10.7%) patients had to discontinue or modify the CFZ dosing regimen. Along with baseline risk stratification, subsequent cardiovascular clinical events and diagnostic follow-up both provided critical data to help identify conditions that could contraindicate the anticancer therapy.

Autophagy and Apoptosis: Current Challenges of Treatment and Drug Resistance in Multiple Myeloma

Over the past two decades, the natural history of multiple myeloma (MM) has evolved dramatically, owing primarily to novel agents targeting MM in the bone marrow microenvironment (BMM) pathways. However, the mechanisms of resistance acquisition remain a mystery and are poorly understood. Autophagy and apoptosis are tightly controlled processes and play a critical role in the cell growth, development, and survival of MM. Genetic instability and abnormalities are two hallmarks of MM. During MM progression, plasma malignant cells become genetically unstable and activate various signaling pathways, resulting in the overexpression of abnormal proteins that disrupt autophagy and apoptosis biological processes. Thus, achieving a better understanding of the autophagy and apoptosis processes and the proteins that crosslinked both pathways, could provide new insights for the MM treatment and improve the development of novel therapeutic strategies to overcome resistance. This review presents a sufficient overview of the roles of autophagy and apoptosis and how they crosslink and control MM progression and drug resistance. Potential combination targeting of both pathways for improving outcomes in MM patients also has been addressed.

Exploring the role and clinical implications of proteasome inhibition in medulloblastoma

Ubiquitin proteasome-mediated protein degradation has been implicated in posttranslational oncogenesis in medulloblastoma. Current research is evaluating the clinical implications of proteasome inhibition as a therapeutic target. In medulloblastoma cell lines, proteasome inhibitors induce apoptosis and inhibit cell proliferation via multiple pathways involving activation of caspase pathways, NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) pathway inhibition, reduced AKT/mTOR pathway activity, and pro-apoptotic protein expression. Second-generation proteasome inhibitors demonstrate blood-brain barrier penetration while maintaining antitumor effect. This review summarizes the ubiquitin-proteasome system in the pathogenesis of medulloblastoma and the potential clinical implications.

From oxygen sensing to angiogenesis: Targeting the hypoxia signaling pathway in metastatic kidney cancer

PURPOSE

This article summarizes examples of current and emerging therapies that target the hypoxia and angiogenesis signaling pathways in the clear cell type of renal cell cancer (RCC), with an emphasis on the hypoxia signaling pathway.

SUMMARY

Mammalian cells transduce signals of decreased oxygen to hypoxia inducible factor (HIF), an intracellular heterodimer that mediates the adaptation of normal and tumor cells to oxygen deprivation. HIF is frequently overexpressed in cancer cells and is involved in the transcriptional activation of many genes essential for cell invasion, migration, survival, and angiogenesis (including vascular endothelial growth factor [VEGF]). Moreover, HIF confers resistance to cytotoxic chemotherapy and radiation therapy and is associated with poor prognosis in patients with cancer. Blocking the activity of HIF inhibits the expression of VEGF and oncogenic pathways, resulting in the inhibition of tumor growth. Interestingly, activation of oncogenes and/or inactivation of tumor suppressor genes (eg, the gene encoding von Hippel-Lindau [VHL] tumor suppressor protein) can activate tumorigenesis even with normal levels of oxygen, providing support for the notion that the HIF-VHL-VEGF axis is amenable to targeted therapies for the treatment of RCC. This article highlights the current understanding of the hypoxia signaling pathway and its relevance to RCC development. Pharmacologic agents targeting the hypoxia and angiogenesis signaling pathways are discussed.

CONCLUSION

Development of novel therapeutic agents that target the hypoxia and angiogenesis signaling pathways holds promise in the management of metastatic clear cell RCC.

Cytotoxicity and Target Modulation in Pediatric Solid Tumors by the Proteasome Inhibitor Carfilzomib

BACKGROUND

Most children with recurrent metastatic solid tumors have high mortality rates. Recent studies have shown that proteasome inhibition leads to effective tumor killing in cells that have acquired treatment resistance and metastatic properties.

OBJECTIVE

The purpose of this study was to test the potential of Carfilzomib (CFZ), a proteasome inhibitor, in refractory pediatric solid tumors, which is currently unknown.

METHODS

A panel of pediatric solid tumor cell lines, including neuroblastoma, Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma, and atypical teratoid rhabdoid tumor (ATRT), was used to evaluate the cytotoxic and proteasomal inhibitory effects of CFZ. A drug scheduling experiment was performed to determine the optimal dose and time to obtain effective cell killing. Combination studies of CFZ with chemotherapeutic drugs of different classes were performed to determine the extent of synergy.

RESULTS

CFZ showed effective cytotoxicity against all cell lines tested (mean IC50 = 7nM, range = 1-20nM) and activity in a fluorophore-tagged cell-based proteasome assay. Drug scheduling experiments showed that the minimum exposure of 4-8 hours/day is needed for effective cumulative killing. CFZ, when combined with chemotherapeutic drugs of different classes, synergistically enhanced the extent of cell death.

CONCLUSIONS

CFZ showed cytotoxic activity against all the solid pediatric cancer cell lines tested. This study provides initial in vitro data on the potential of CFZ to treat pediatric solid tumors and supports further investigations into the components of drug scheduling, biological correlates, and drug combinations for future early phase clinical trials in children.

Effects of Carfilzomib Therapy on Left Ventricular Function in Multiple Myeloma Patients

Background: Carfilzomib improves the prognosis of multiple myeloma (MM) patients but significantly increases cardiovascular toxicity. The timing and effect of Carfilzomib therapy on the left ventricular function is still under investigation. We sought to assess the echocardiographic systo-diastolic changes, including global longitudinal strain (GLS), in patients treated with Carfilzomib and to identify predictors of increased risk of cardiovascular adverse events (CVAEs) during therapy.

Methods: Eighty-eight patients with MM performed a baseline cardiovascular evaluation comprehensive of transthoracic echocardiogram (TTE) before the start of Carfilzomib therapy and after 6 months. All patients were clinically followed up to early identify the occurrence of CVAEs during the whole therapy duration.

Results: After Carfilzomib treatment, mean GLS slightly decreased (−22.2% ± 2.6 vs. −21.3% ± 2.5; p < 0.001). Fifty-eight percent of patients experienced CVAEs during therapy: 71% of them had uncontrolled hypertension, and 29% had major CVAEs or CV events not related to arterial hypertension. GLS variation during therapy was not related to an increased risk of CVAEs; however, patients with baseline GLS ≥ −21% and/or left ventricular ejection fraction (LVEF) ≤ 60% had a greater risk of major CVAEs (OR = 6.2, p = 0.004; OR = 3.7, p = 0.04, respectively). Carfilzomib led to a higher risk of diastolic dysfunction (5.6 vs. 13.4%, p = 0.04) and to a rise in E/e′ ratio (8.9 ± 2.7 vs. 9.7 ± 3.7; p = 0.006).

Conclusion: Carfilzomib leads to early LV function impairment early demonstrated by GLS changes and diastolic dysfunction. Baseline echocardiographic parameters, especially GLS and LVEF, might improve cardiovascular risk stratification before treatment.

Risk Stratification and Management of Arterial Hypertension and Cardiovascular Adverse Events Related to Cancer Treatments: An Oncology Network from Piedmont and Aosta Valley (North-Western Italy) Consensus Document

Cancer patients receiving a potentially cardiotoxic oncologic therapy have an increased risk of cardiovascular adverse events (CVAEs), especially in presence of concomitant arterial hypertension (AH). Therefore, cancer patients should be evaluated before, during and after cardiotoxic treatments, to early identify new-onset or worsening AH or CVAEs. An expert panel of oncology networks from Piedmont and Aosta Valley (North-Western Italy) aimed to provide recommendations to support health professionals in selecting the best management strategies for patients, considering the impact on outcome and the risk–benefit ratio of diagnostic/therapeutic tools. We proposed an useful document for evaluating and managing AH related to cancer treatments. Patients should be divided into 4 cardiovascular (CV) risk groups before starting potentially cardiotoxic therapies: patients with low/moderate risk who should be entirely evaluated by oncologists and patients with high/very high risk who should be referred to a cardiologist or arterial hypertension specialist. According to the CV risk class, every patient should be followed up during cancer treatment to monitor any possible CV complications. Adequate control of AH related to antineoplastic treatments is crucial to prevent severe CVAEs. In the presence of high-profile risk or lack of response to anti-hypertensive therapy, the patients should be managed with a cardiovascular-oncology expert center.

A decision process for drug discovery in retinoblastoma

Intraocular retinoblastoma treatment has changed radically over the last decade, leading to a notable improvement in ocular survival. However, eyes that relapse remain difficult to treat, as few alternative active drugs are available. More challenging is the scenario of central nervous system (CNS) metastasis, in which almost no advancements have been made. Both clinical scenarios represent an urgent need for new drugs. Using an integrated multidisciplinary approach, we developed a decision process for prioritizing drug selection for local (intravitreal [IVi], intrathecal/intraventricular [IT/IVt]), systemic, or intra-arterial chemotherapy (IAC) treatment by means of high-throughput pharmacological screening of primary cells from two patients with intraocular tumor and CNS metastasis and a thorough database search to identify clinical and biopharmaceutical data. This process identified 169 compounds to be cytotoxic; only 8 are FDA-approved, lack serious toxicities and available for IVi administration. Four of these agents could also be delivered by IT/IVt. Twelve FDA-approved drugs were identified for systemic delivery as they are able to cross the blood-brain barrier and lack serious adverse events; four drugs are of oral usage and six compounds that lack vesicant or neurotoxicity could be delivered by IAC. We also identified promising compounds in preliminary phases of drug development including inhibitors of survivin, antiapoptotic Bcl-2 family proteins, methyltransferase, and kinesin proteins. This systematic approach may be applied more broadly to prioritize drugs to be repurposed or to identify novel hits for use in retinoblastoma treatment.

The role of carfilzomib in treatment of newly diagnosed multiple myeloma

Despite improvement of prognosis since approval of proteasome inhibitors and immunomodulatory drugs, myeloma remains largely incurable. The outcome of first-line treatment is known to be crucial for survival and, therefore, implementation of novel strategies remains one of the key aims of clinical myeloma research. Since approval of carfilzomib for relapsed and refractory multiple myeloma, a new therapeutic option with a favorable safety profile regarding neuropathy is available. Regarding its superior response rates and progression-free survival (PFS) when combined with other agents in heavily pretreated patients, the compound rapidly became a matter of great interest in search for first-line treatment. With an ORR up to 98% and promising PFS data, it might become an important partner in treatment of newly diagnosed myeloma.

Improving the efficacy of proteasome inhibitors in the treatment of renal cell carcinoma by combination with the human immunodeficiency virus (HIV)-protease inhibitors lopinavir or nelfinavir

OBJECTIVES

To assess the potential of second-generation proteasome inhibition by carfilzomib and its combination with the human immunodeficiency virus (HIV) protease inhibitors (HIV-PIs) lopinavir and nelfinavir in vitro for improved treatment of clear cell renal cell cancer (ccRCC).

MATERIALS AND METHODS

Cytotoxicity, reactive oxygen species (ROS) production, and unfolded protein response (UPR) activation of proteasome inhibitors, HIV-PIs, and their combination were assessed in three cell lines and primary cells derived from three ccRCC tumours by MTS assay, flow cytometry, quantitative reverse transcriptase-polymerase chain reaction and western blot, respectively. Proteasome activity was determined by activity based probes. Flow cytometry was used to assess apoptosis by annexin V/propidium iodide assay and ATP-binding cassette sub-family B member 1 (ABCB1) activity by MitoTracker™ Green FM efflux assay (Thermo Fisher Scientific, MA, USA).

RESULTS

Lopinavir and nelfinavir significantly increased the cytotoxic effect of carfilzomib in all cell lines and primary cells. ABCB1 efflux pump inhibition, induction of ROS production, and UPR pre-activation by lopinavir were identified as underlying mechanisms of this strong synergistic effect. Combined treatment led to unresolved protein stress, increased activation of pro-apoptotic UPR pathway, and a significant increase in apoptosis.

CONCLUSION

The combination of the proteasome inhibitor carfilzomib and the HIV-PIs lopinavir and nelfinavir has a strong synergistic cytotoxic activity against ccRCCin vitro at therapeutically relevant drug concentrations. This effect is most likely explained by synergistic UPR triggering and ABCB1-modulation caused by HIV-PIs. Our findings suggest that combined treatment of second-generation proteasome inhibitors and HIV-PIs should be investigated in patients with metastatic RCC within a clinical trial.

An overview of the role of carfilzomib in the treatment of multiple myeloma

INTRODUCTION

Carfilzomib is a second-generation proteasome inhibitor that binds selectively and irreversibly with the chymotrypsin-like site of the proteolytic core. Its initial approval by the Food and Drug Administration, as monotherapy for relapsed/refractory multiple myeloma (RR-MM), followed soon by a global authorization of its combination with dexamethasone or with lenalidomide plus dexamethasone for the treatment of RR-MM after 1-3 prior lines. In order to optimize its administration, carfilzomib is currently examined in different doses and regimens in relapsed/refractory as well as in newly diagnosed myeloma. Areas covered: This review will focus on the introduction of carfilzomib as an effective anti-myeloma treatment, describing the evolution of the drug from its pre-clinical development to its established use by phase III clinical trials. Based on the latest evidence, we will present its mechanism of action, its efficacy and its toxicity profile on treated myeloma patients and we will try to reply to all raised concerns about its current use. Expert opinion: Either alone or in combination with other agents, carfilzomib seems to be an effective and safe therapeutic option for MM management. Results of ongoing trials are expected to update its application, even at an earlier level of the disease course.

Novel Proteasome Inhibitors and Histone Deacetylase Inhibitors: Progress in Myeloma Therapeutics

The unfolded protein response is responsible for the detection of misfolded proteins and the coordination of their disposal and is necessary to maintain the cellular homoeostasis. Multiple myeloma cells secrete large amounts of immunoglobulins, proteins that need to be correctly folded by the chaperone system. If this process fails, the misfolded proteins have to be eliminated by the two main garbage-disposal systems of the cell: proteasome and aggresome. The blockade of either of these systems will result in accumulation of immunoglobulins and other toxic proteins in the cytoplasm and cell death. The simultaneous inhibition of the proteasome, by proteasome inhibitors (PIs) and the aggresome, by histone deacetylase inhibitors (HDACi) results in a synergistic increase in cytotoxicity in myeloma cell lines. This review provides an overview of mechanisms of action of second-generation PIs and HDACi in multiple myeloma (MM), the clinical results currently observed with these agents and assesses the potential therapeutic impact of the different agents in the two classes. The second-generation PIs offer benefits in terms of increased efficacy, reduced neurotoxicity as off-target effect and may overcome resistance to bortezomib because of their different chemical structure, mechanism of action and biological properties. HDACi with anti-myeloma activity in clinical development discussed in this review include vorinostat, panobinostat and selective HDAC6 inhibitor, ricolinostat.