An Electrodiagnostic Evaluation of the Effect of Pre-existing Peripheral Nervous System Disorders in Patients Treated with the Novel Proteasome Inhibitor Bortezomib

Vincristine- and bortezomib-induced neuropathies - from bedside to bench and back

Vincristine and bortezomib are effective chemotherapeutics widely used to treat hematological cancers. Vincristine blocks tubulin polymerization, whereas bortezomib is a proteasome inhibitor. Despite different mechanisms of action, the main non-hematological side effect of both is peripheral neuropathy that can last long after treatment has ended and cause permanent disability. Many different cellular and animal models of various aspects of vincristine and bortezomib-induced neuropathies have been generated to investigate underlying molecular mechanisms and serve as platforms to develop new therapeutics. These models revealed that bortezomib induces several transcriptional programs in dorsal root ganglia that result in the activation of different neuroinflammatory pathways and secondary central sensitization. In contrast, vincristine has direct toxic effects on the axon, which are accompanied by changes similar to those observed after nerve cut. Axon degeneration following both vincristine and bortezomib is mediated by a phylogenetically ancient, genetically encoded axon destruction program that leads to the activation of the Toll-like receptor adaptor SARM1 (sterile alpha and TIR motif containing protein 1) and local decrease of nicotinamide dinucleotide (NAD+). Here, I describe current in vitro and in vivo models of vincristine- and bortezomib induced neuropathies, present discoveries resulting from these models in the context of clinical findings and discuss how increased understanding of molecular mechanisms underlying different aspects of neuropathies can be translated to effective treatments to prevent, attenuate or reverse vincristine- and bortezomib-induced neuropathies. Such treatments could improve the quality of life of patients both during and after cancer therapy and, accordingly, have enormous societal impact.

Proteasome inhibitors in cancer therapy: Treatment regimen and peripheral neuropathy as a side effect

Proteasomal system plays an important role in protein turnover, which is essential for homeostasis of cells. Besides degradation of oxidized proteins, it is involved in the regulation of many different signaling pathways. These pathways include mainly cell differentiation, proliferation, apoptosis, transcriptional activation and angiogenesis. Thus, proteasomal system is a crucial target for treatment of several diseases including neurodegenerative diseases, cystic fibrosis, atherosclerosis, autoimmune diseases, diabetes and cancer. Over the last fifteen years, proteasome inhibitors have been tested to highlight their mechanisms of action and used in the clinic to treat different types of cancer. Proteasome inhibitors are mainly used in combinational therapy along with classical chemo-radiotherapy. Several studies have proved their significant effects but serious side effects such as peripheral neuropathy, limits their use in required effective doses. Recent studies focus on peripheral neuropathy as the primary side effect of proteasome inhibitors. Therefore, it is important to delineate the underlying mechanisms of peripheral neuropathy and develop new inhibitors according to obtained data. This review will detail the role of proteasome inhibition in cancer therapy and development of peripheral neuropathy as a side effect. Additionally, new approaches to prevent treatment-limiting side effects will be discussed in order to help researchers in developing effective strategies to overcome side effects of proteasome inhibitors.

Electrophysiological, behavioral and histological characterization of paclitaxel, cisplatin, vincristine and bortezomib-induced neuropathy in C57Bl/6 mice

Polyneuropathy is a frequent and potentially severe side effect of clinical tumor chemotherapy. The goal of this study was to characterize paclitaxel-, cisplatin-, vincristine- and bortezomib-induced neuropathy in C57BL/6 mice with a comparative approach. The phenotype of the animals was evaluated at four time points with behavioral and electrophysiological tests, followed by histology. Treatment protocols used in this study were well tolerated and induced a sensory and predominantly axonal polyneuropathy. Behavioral testing revealed normal motor coordination, whereas all mice receiving verum treatment developed mechanical allodynia and distinct gait alterations. Electrophysiological evaluation showed a significant decrease of the caudal sensory nerve action potential amplitude for all cytostatic agents and a moderate reduction of nerve conduction velocity for cisplatin and paclitaxel. This finding was confirmed by histological analysis of the sciatic nerve which showed predominantly axonal damage: Paclitaxel and vincristine affected mostly large myelinated fibers, bortezomib small myelinated fibers and cisplatin damaged all types of myelinated fibers to a similar degree. Neuropathic symptoms developed faster in paclitaxel and vincristine treated animals compared to cisplatin and bortezomib treatment. The animal models in this study can be used to elucidate pathomechanisms underlying chemotherapy-induced polyneuropathy and for the development of novel therapeutic and preventative strategies.

Bortezomib-induced painful neuropathy in patients with multiple myeloma

Neurotoxicity towards the peripheral nervous system which appears clinically in the form of painful neuropathy is an essential dose-limiting factor during the treatment of multiple myeloma. In this review article different forms of this painful neuropathy are presented together with currently available diagnostic tools which are usually applied to confirm the diagnosis. Also, the most often used neurological scales estimating neurological deficit are presented. Special attention is paid to the management of the reversibility of bortezomib-induced neuropathic pain.

Prospective evaluation of the toxicity profile of proteasome inhibitor-based therapy in renal transplant candidates and recipients

BACKGROUND

A prospective intermediate-term evaluation of toxicities associated with bortezomib therapy for antibody-mediated rejection (AMR) and desensitization was conducted.

METHODS

Patients were graded for bortezomib-related toxicities: hematologic and gastrointestinal toxicities by Common Terminology Criteria for Adverse Events and peripheral neuropathy by modified Functional Assessment of Cancer Therapy questionnaire and Common Terminology Criteria for Adverse Events.

RESULTS

Fifty-one patients treated for AMR and 19 patients treated for desensitization received 96 bortezomib cycles (1.3 mg/m(2) ×4 doses); mean (SD) follow-up was 16.3 (9.0) months. Patients treated for AMR and patients treated for desensitization were similar in age, gender, ethnicity, and baseline peripheral neuropathy. Patients treated for AMR received a mean (SD) of 4.9 (2.0) bortezomib doses in 1.3 (0.5) cycles; and patients treated for desensitization, a mean of 7.3 (1.6) doses in 1.8 (0.4) cycles. Prevalence of diabetes and anemia were higher at baseline in patients treated for AMR. In the AMR cohort, two cases of cytomegalovirus infection, two cases of BK virus infection, and one case of Epstein-Barr virus infection were observed. No cases of viral infection were observed in the desensitization cohort. Malignancies were not observed. Significant bortezomib toxicities included anemia and peripheral neuropathy, which were manageable. Anemia was more common in patients treated for AMR; and peripheral neuropathy, more common in patients treated for desensitization.

CONCLUSIONS

Bortezomib-related toxicities in kidney transplant candidates and recipients are low in incidence and severity and vary based on treatment population.

Chemotherapy-induced neuropathic pain

PURPOSE OF REVIEW

To discuss the importance, clinical features, possible pathology and treatments of chemotherapy-induced neuropathic pain. Newer biological agents such as bortezomib will be considered in greater detail.

RECENT FINDINGS

Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent complication of common anticancer therapies. It may lead to treatment compromise, significantly adds to the symptom burden and interferes with quality of life of cancer survivors. Recent investigations have identified processes involved in CIPN which may give some insight for the development of novel treatments. CIPN induced by different anticancer therapies may be heterogeneous and present as distinct neuropathic pains. Recent work has focussed on the newer anticancer drugs such as bortezomib. Contemporaneous studies have failed to find good evidence for the use of several common antineuropathic agents and further research is required.

SUMMARY

Painful CIPN remains under recognized and undertreated. It is an important cause of pain during cancer treatment and is a common pain in the cancer survivor. Difficulties in assessment and limitations in treatment contribute to management problems. Improvements in education (patient and clinician), assessment and treatment would potentially reduce the often debilitating effects of painful CIPN.

Peripheral neuropathy during bortezomib treatment of multiple myeloma: a review of recent studies

Treatment-emergent peripheral neuropathy (PN) is an important dose-limiting toxicity during treatment of multiple myeloma (MM). Bortezomib-induced PN (BIPN) occurred in 37-44% of clinical trial patients with MM, with the cumulative treatment dose as its single most significant predictor. This review discusses the clinical profile of BIPN in the treatment of MM and guidelines for its management. Lower rates of BIPN observed during treatment of solid tumors compared with rates of hematologic cancers are also discussed. Several areas of research are reviewed that may improve the management of BIPN, including co-therapies with the novel heat shock protein inhibitor tanespimycin, which appears to reduce the incidence of BIPN, and recent studies with second-generation proteasome inhibitors such as carfilzomib and NPI-0052. Adherence to the National Cancer Institute dose-modification algorithm is the most effective method for mitigating BIPN. Reversal of BIPN after treatment cessation occurs in most cases, but recovery in some patients takes as long as 1.7 years, and some individuals fail to return to baseline neurologic function. BIPN can cause a significant reduction in quality of life, primarily due to severe treatment-emergent pain. Ongoing research may provide additional information about the mechanism of BIPN and strategies to reduce PN.

A high-dose bortezomib neuropathy with sensory ataxia and myelin involvement

Bortezomib, a proteasome inhibitor used in the treatment of multiple myeloma, is known to induce an axonal, dose-dependent neuropathy clinically characterized by pain, paresthesias, burning dysesthesias and numbness. In this study, we describe a patient treated with high-dose bortezomib whose main clinical feature was severe sensory ataxia. Electrodiagnostic studies showed, other than axonal changes, myelin involvement.

Barriers to rehabilitation of the neurosurgical spine cancer patient

The treatment of metastatic spine tumors has evolved significantly over the past 20 years due largely to improvements in magnetic resonance imaging; decompressive surgical techniques, spinal instrumentation, and high-dose conformal radiation. These advances have improved our ability to provide meaningful palliation for patients who often have significant medical and cancer-related issues. Despite technical advances that have improved our ability to maintain neurologic function, stabilize the spine, and prevent local tumor recurrences, significant barriers to rehabilitation remain. This article reviews these primary barriers to rehabilitation of the cancer patient following spine surgery and emphasizes the importance of diagnostic accuracy and a comprehensive team approach to the treatment of pain and other disorders in this population.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.