Pathophysiology of drug-induce peripheral neuropathy in patients with multiple myeloma

Efficacy and safety analysis of bortezomib-based triplet regimens sequential lenalidomide in newly diagnosed multiple myeloma patients

The aim of this study is to analyze the efficacy and safety of sequential therapy with bortezomib-based triplet regimens without lenalidomide (PXD, including VTD, PAD, and VCD) followed by continuous lenalidomide and dexamethasone (Rd) or bortezomib and dexamethasone (Vd) treatment. The main objective is to evaluate the advantages of PXD followed by Rd compared to the combinations of bortezomib-lenalidomide-dexamethasone (VRd) in newly diagnosed multiple myeloma (NDMM). Fifty-eight nontransplant NDMM patients who were admitted to our department from 2017 to 2019 were included in this study. Bortezomib-based triplet regimens were initially selected and followed by Rd or Vd as continuous treatment once the patients achieved partial remission (PR) or better response. The efficacy and safety of the patients were observed. The Rd continuous treatment cohort was compared with historical data from the EVOLUTION trial on continuous VRd treatment. In our cohort, the overall survival rate was 100%, and progression-free survival (PFS) was 38.5% after a median of 19 (4-36) cycles of Rd continuous therapy was applied. During the follow-up period, the best outcome assessments achieved were 53.8% complete response (CR) and 84.6% excellent partial response (VGPR). A total of 23.1% had grade 3-4 or higher drug-related adverse reactions, mainly hematological toxicity, and no patients died of adverse reactions. Compared with the Vd group, the Rd group had a better PFS and VGPR rate (2-year PFS: 92.3% vs. 56.3%, P = 0.002; 3-year PFS: 69.2% vs. 8.0%, P < 0.001; VGPR: 84.6% vs. 69.2%, P = 0.02). No significant differences were found in ORR (100% vs. 92.3%) or CR (53.8% vs. 35.7%, P = 0.082). Compared with the EVOLUTION study, patients in the Rd group had a more advanced disease stage (stage III rate of 40% vs. 19%, P = 0.039) and worse physical status (KPS 50-60 rate of 25.0% vs. 2.0%, P = 0.000). However, a higher proportion of ORR (100% vs. 73.0%, P < 0.001), VGPR or better (75.0% vs. 32.0%, P < 0.001), and PFS at 12 months (90.0% vs. 68%, P = 0.011) were achieved. Sequential administration of bortezomib-based triplet regimens without lenalidomide as an initial therapy followed by Rd as a continuous treatment may not be inferior to VRd for first-line treatment in NDMM patients.

Chemotherapy-Induced Peripheral Neuropathy: Epidemiology, Pathomechanisms and Treatment

PURPOSE

This review provides an update on the current clinical, epidemiological and pathophysiological evidence alongside the diagnostic, prevention and treatment approach to chemotherapy-induced peripheral neuropathy (CIPN).

FINDINGS

The incidence of cancer and long-term survival after treatment is increasing. CIPN affects sensory, motor and autonomic nerves and is one of the most common adverse events caused by chemotherapeutic agents, which in severe cases leads to dose reduction or treatment cessation, with increased mortality. The primary classes of chemotherapeutic agents associated with CIPN are platinum-based drugs, taxanes, vinca alkaloids, bortezomib and thalidomide. Platinum agents are the most neurotoxic, with oxaliplatin causing the highest prevalence of CIPN. CIPN can progress from acute to chronic, may deteriorate even after treatment cessation (a phenomenon known as coasting) or only partially attenuate. Different chemotherapeutic agents share both similarities and key differences in pathophysiology and clinical presentation. The diagnosis of CIPN relies heavily on identifying symptoms, with limited objective diagnostic approaches targeting the class of affected nerve fibres. Studies have consistently failed to identify at-risk cohorts, and there are no proven strategies or interventions to prevent or limit the development of CIPN. Furthermore, multiple treatments developed to relieve symptoms and to modify the underlying disease in CIPN have failed.

IMPLICATIONS

The increasing prevalence of CIPN demands an objective approach to identify at-risk patients in order to prevent or limit progression and effectively alleviate the symptoms associated with CIPN. An evidence base for novel targets and both pharmacological and non-pharmacological treatments is beginning to emerge and has been recognised recently in publications by the American Society of Clinical Oncology and analgesic trial design expert groups such as ACTTION.

The Association of Neuronal Stress with Activating Transcription Factor 3 in Dorsal Root Ganglion of in vivo and in vitro Models of Bortezomib- Induced Neuropathy

BACKGROUND

The notion that proteasome inhibitor bortezomib (BTZ) induced intracellular oxidative stress resulting in peripheral neuropathy has been generally accepted. The association of mitochondrial dysfunction, cell apoptosis, and endoplasmic reticulum (ER) stress with intracellular oxidative stress is ambiguous and still needs to be investigated. The activation of activating transcription factor 3 (ATF3) is a stress-hub gene which was upregulated in dorsal root ganglion (DRG) neurons after different kinds of peripheral nerve injuries.

OBJECTIVE

To investigate a mechanism underlying the action of BTZ-induced intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress via activation of ATF3.

METHODS

Primary cultured DRG neurons with BTZ induced neurotoxicity and DRG from BTZ induced painful peripheral neuropathic rats were used to approach these questions.

RESULTS

BTZ administration caused the upregulation of ATF3 paralleled with intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress in DRG neurons both in vitro and in vivo. Blocking ATF3 signaling by small interfering RNA (siRNA) gene silencing technology resulted in decreased intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress in DRG neurons after BTZ treatment.

CONCLUSION

This study exhibited important mechanistic insight into how BTZ induces neurotoxicity through the activation of ATF3 resulting in intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress and provided a novel potential therapeutic target by blocking ATF3 signaling.

Effect of Bortezomib on Global Gene Expression in PC12-Derived Nerve Cells

Peripheral neuropathy is one of the main side-effects of novel therapeutics used in oncohematological diseases, but the molecular basis underlying its development and progression as well as neurotoxicity mechanisms induced by the use of these therapeutics are still not fully elucidated. The aim of this study was to demonstrate the effect of bortezomib on global gene and miRNA expression on PC12-derived nerve cells. Microarray analysis showed that expression of 1383 genes was downregulated at least two fold and 671 genes were upregulated at least two fold in PC12-derived nerve cells treated with bortezomib compared to untreated/control cells. Analysis of functional annotations mainly identified downregulated processes (e.g., regulation of cell cycle, DNA replication and repair, regulation of cell migration, neuron projection morphogenesis and neurotransmitter secretion). The result of miRNA expression analysis demonstrated only 11 significantly downregulated miRNAs (at least two fold) in bortezomib-treated PC12-derived nerve cells vs. control cells. MiRNAs regulate gene expression, therefore we decided to conduct an analysis comparing the outcomes of miRNA microarray expression data to the obtained mRNA data. The most interesting miRNA–target gene correlation is downregulated expression of miR-130a-3p and miR-152-3p and as a result of this downregulation the expression of the Gadd45 increased. This gene is a member of a group of genes, the transcript expression of which is enhanced after stressful growth arrest conditions and treatment with DNA-damaging agents like drugs or mutagens.

High Effectiveness in Actions of Carfilzomib on Delayed-Rectifier K+ Current and on Spontaneous Action Potentials

Carfilzomib (CFZ, Kyprolis^®) is widely recognized as an irreversible inhibitor of proteasome activity; however, its actions on ion currents in electrically excitable cells are largely unresolved. The possible actions of CFZ on ionic currents and membrane potential in pituitary GH₃, A7r5 vascular smooth muscle, and heart-derived H9c2 cells were extensively investigated in this study. The presence of CFZ suppressed the amplitude of delayed-rectifier K⁺ current (I_K(DR)) in a time-, state-, and concentration-dependent manner in pituitary GH₃ cells. Based on minimal reaction scheme, the value of dissociation constant for CFZ-induced open-channel block of I_K(DR) in these cells was 0.33 µM, which is similar to the IC₅₀ value (0.32 µM) used for its efficacy on inhibition of I_K(DR) amplitude. Recovery from I_K(DR) block by CFZ (0.3 µM and 1 µM) could be well fitted by single exponential with 447 and 645 ms, respectively. The M-type K⁺ current, another type of K⁺ current elicited by low-threshold potential, was slightly suppressed by CFZ (1 µM). Under current-clamp condition, addition of CFZ depolarized GH₃ cells, broadened the duration of action potentials as well as raised the firing frequency. In A7r5 vascular smooth muscle cells or H9c2 cardiac cells, the CFZ-induced inhibition of I_K(DR) remained efficacious. Therefore, our study led us to reflect that CFZ or other structurally similar compounds should somehow act on the activity of membrane K_V channels through which they influence the functional activities in different types of electrically excitable cells such as endocrine, neuroendocrine cells, smooth muscle cells, or heart cells, if similar in vivo findings occur.