Peripheral neuropathy with microtubule-targeting agents: occurrence and management approach

Chemotherapy-Induced Peripheral Neuropathy in Egyptian Patients: Single Institution Retrospective Analysis

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a major toxicity that requires treatment modification or cessation and worsens patients’ quality of life. Its incidence is 30–40%. Occurrence and severity depend on treatment- and patient-related factors. The symptoms are self-limiting with recovery rate about 50%. Methods: This retrospective analysis took place in our chemotherapy unit. We included patients treated between January 2014 and December 2015. Results: 250 patients were eligible. 53 received paclitaxel, 78 received docetaxel, 64 received cisplatin and 55 received oxaliplatin. Mean age was 50.11 years. Frequency of CIPN was 46.8% (Grade I 70.9%, GII 24.7%, GIII 4.4%). It was 74% with oxaliplatin, 73.5% with paclitaxel, 35.9% with cisplatin and 17.9% with docetaxel. After median of 6 months 24% of patients recovered completely. No significant correlation between occurrence of CIPN and age (p = 0.781), while was significant with cisplatin (p = 0.043). Diabetic patients had higher incidence (p = 0.007). With cisplatin, median cumulative dose of 450 mg/m2 and ≥ 6 cycles had higher incidence of CIPN (p 0.006 and 0.010; respectively). With oxaliplatin, none was correlated with CIPN frequence. With paclitaxel, CIPN was more frequent if ≥ 4 cycles were received (p = 0.005). With docetaxel, > 4 cycles or cumulative dose ≥ 360 mg/m2 had higher occurrence of GII CIPN (p < 0.001 for both). Conclusion: CIPN is common problem that affects patients’ quality of life and leads to treatment interruption. There are many factors affecting its incidence and severity.

Indibulin dampens microtubule dynamics and produces synergistic antiproliferative effect with vinblastine in MCF-7 cells: Implications in cancer chemotherapy

Indibulin, a synthetic inhibitor of tubulin assembly, has shown promising anticancer activity with a minimal neurotoxicity in preclinical animal studies and in Phase I clinical trials for cancer chemotherapy. Using time-lapse confocal microscopy, we show that indibulin dampens the dynamic instability of individual microtubules in live breast cancer cells. Indibulin treatment also perturbed the localization of end-binding proteins at the growing microtubule ends in MCF-7 cells. Indibulin reduced inter-kinetochoric tension, produced aberrant spindles, activated mitotic checkpoint proteins Mad2 and BubR1, and induced mitotic arrest in MCF-7 cells. Indibulin-treated MCF-7 cells underwent apoptosis-mediated cell death. Further, the combination of indibulin with an anticancer drug vinblastine was found to exert synergistic cytotoxic effects on MCF-7 cells. Interestingly, indibulin displayed a stronger effect on the undifferentiated neuroblastoma (SH-SY5Y) cells than the differentiated neuronal cells. Unlike indibulin, vinblastine and colchicine produced similar depolymerizing effects on microtubules in both differentiated and undifferentiated SH-SY5Y cells. The data indicated a possibility that indibulin may reduce chemotherapy-induced peripheral neuropathy in cancer patients.

Eribulin in Heavily Pretreated Metastatic Breast Cancer Patients in the Real World: A Retrospective Study

OBJECTIVES

The aim of this study was to investigate efficacy and safety of eribulin in heavily pretreated patients with advanced breast cancer (BC) in a real-life setting.

METHODS

This retrospective monocentric study included patients with HER-2-negative metastatic BC, pretreated with anthracyclines and taxanes, who were referred to the Oncology Department of Spedali Civili of Brescia from May 2012 to April 2017. Patients received the same dose of eribulin as that used in the EMBRACE trial: 1.4 mg/m2 on days 1 and 8 every 21 days.

RESULTS

In a total of 53 patients, 32% obtained a partial response, 11% a stable disease, and 43% a clinical benefit (CB). After a median follow-up of 36 months, median progression-free survival (PFS) was 4.7 months and median overall survival (OS) 13.53 months. Median PFS was significantly longer in patients who reported a CB compared to those with no CB, while survival outcomes (PFS and OS) were better in patients who received > 6 cycles of eribulin. Eribulin showed a good tolerability profile with acceptable toxicities, similar to those reported in EMBRACE.

CONCLUSIONS

Our experience in a real-world setting confirms the activity, efficacy, and good tolerability profile of eribulin in heavily pretreated BC patients.

Microtubule dynamics: moving toward a multi-scale approach

Microtubule self-assembly dynamics serve to facilitate many vital cellular functions, such as chromosome segregation during mitosis and synaptic plasticity. However, the detailed atomistic basis of assembly dynamics has remained an unresolved puzzle. A key challenge is connecting together the vast range of relevant length-time scales, events happening at time scales ranging from nanoseconds, such as tubulin molecular interactions (Å-nm), to minutes-hours, such as the cellular response to microtubule dynamics during mitotic progression (μm). At the same time, microtubule interactions with associated proteins and binding agents, such as anti-cancer drugs, can strongly affect this dynamic process through atomic-level mechanisms that remain to be elucidated. New high-resolution technologies for investigating these interactions, including cryo-electron microscopy (EM) techniques and total internal reflection fluorescence (TIRF) microscopy, are yielding important new insights. Here, we focus on recent studies of microtubule dynamics, both theoretical and experimental, and how these findings shed new light on this complex phenomenon across length-time scales, from Å to μm and from nanoseconds to minutes.

Peripheral Neuropathy Induced by Microtubule-Targeted Chemotherapies: Insights into Acute Injury and Long-term Recovery

Chemotherapy-induced peripheral neuropathy (CIPN) is a major cause of disability in cancer survivors. CIPN investigations in preclinical model systems have focused on either behaviors or acute changes in nerve conduction velocity (NCV) and amplitude, but greater understanding of the underlying nature of axonal injury and its long-term processes is needed as cancer patients live longer. In this study, we used multiple independent endpoints to systematically characterize CIPN recovery in mice exposed to the antitubulin cancer drugs eribulin, ixabepilone, paclitaxel, or vinorelbine at MTDs. All of the drugs ablated intraepidermal nerve fibers and produced axonopathy, with a secondary disruption in myelin structure within 2 weeks of drug administration. In addition, all of the drugs reduced sensory NCV and amplitude, with greater deficits after paclitaxel and lesser deficits after ixabepilone. These effects correlated with degeneration in dorsal root ganglia (DRG) and sciatic nerve and abundance of Schwann cells. Although most injuries were fully reversible after 3-6 months after administration of eribulin, vinorelbine, and ixabepilone, we observed delayed recovery after paclitaxel that produced a more severe, pervasive, and prolonged neurotoxicity. Compared with other agents, paclitaxel also displayed a unique prolonged exposure in sciatic nerve and DRG. The most sensitive indicator of toxicity was axonopathy and secondary myelin changes accompanied by a reduction in intraepidermal nerve fiber density. Taken together, our findings suggest that intraepidermal nerve fiber density and changes in NCV and amplitude might provide measures of axonal injury to guide clinical practice.Significance: This detailed preclinical study of the long-term effects of widely used antitubulin cancer drugs on the peripheral nervous system may help guide clinical evaluations to improve personalized care in limiting neurotoxicity in cancer survivors. Cancer Res; 78(3); 817-29. ©2017 AACR.

CXCR1/2 pathways in paclitaxel-induced neuropathic pain

Chemotherapy-induced peripheral neuropathy (CIPN) is a type of neuropathic pain that represents a frequent and serious consequence of chemotherapy agents. Over the last years, significant progress has been achieved in elucidating the underlying pathogenesis of CIPN. The interference of taxanes with microtubule has been proposed as a mechanism that leads to altered axonal transport and to permanent neurological damages. The inflammatory process activated by chemotherapeutic agents has been considered as a potential trigger of nociceptive process in CIPN.

In this study we investigated the effect of reparixin, an inhibitor of CXCR1/CXCR2, in suppressing the development of paclitaxel-induced nociception in rats. Moreover, reparixin activity in reversing the neurotoxic effects induced by paclitaxel or GRO/KC in F11 cells was also analyzed.

Reparixin administered by continuous infusion ameliorated paclitaxel-induced mechanical and cold allodynia in rats. In F11 cells, reparixin was able to inhibit the increase of acetyladed α-tubulin induced both by paclitaxel and GRO/KC. The subsequent experiments were performed in order to dissect the signal transduction pathways under GRO/KC control, eventually modulated by paclitaxel and/or reparixin. To this aim we found that reparixin significantly counteracted p-FAK, p-JAK2/p-STAT3, and PI3K-p-cortactin activation induced either by paclitaxel or GRO/KC.

Overall the present results have identified IL-8/CXCR1/2 pathway as a mechanism involved in paclitaxel-induced peripheral neuropathy. In particular, the obtained data suggest that the inhibition of CXCR1/2 combined with standard taxane therapy, in addition to potentiating the taxane anti-tumor activity can reduce chemotherapy-induced neurotoxicity, thus giving some insight for the development of novel treatments.

Microtubins: a novel class of small synthetic microtubule targeting drugs that inhibit cancer cell proliferation

Microtubule targeting drugs like taxanes, vinca alkaloids, and epothilones are widely-used and effective chemotherapeutic agents that target the dynamic instability of microtubules and inhibit spindle functioning. However, these drugs have limitations associated with their production, solubility, efficacy and unwanted toxicities, thus driving the need to identify novel antimitotic drugs that can be used as anticancer agents. We have discovered and characterized the Microtubins (Microtubule inhibitors), a novel class of small synthetic compounds, which target tubulin to inhibit microtubule polymerization, arrest cancer cells predominantly in mitosis, activate the spindle assembly checkpoint and trigger an apoptotic cell death. Importantly, the Microtubins do not compete for the known vinca or colchicine binding sites. Additionally, through chemical synthesis and structure-activity relationship studies, we have determined that specific modifications to the Microtubin phenyl ring can activate or inhibit its bioactivity. Combined, these data define the Microtubins as a novel class of compounds that inhibit cancer cell proliferation by perturbing microtubule polymerization and they could be used to develop novel cancer therapeutics.

Germline genetic variants with implications for disease risk and therapeutic outcomes

Genetic testing has multiple clinical applications including disease risk assessment, diagnosis, and pharmacogenomics. Pharmacogenomics can be utilized to predict whether a pharmacologic therapy will be effective or to identify patients at risk for treatment-related toxicity. Although genetic tests are typically ordered for a distinct clinical purpose, the genetic variants that are found may have additional implications for either disease or pharmacology. This review will address multiple examples of germline genetic variants that are informative for both disease and pharmacogenomics. The discussed relationships are diverse. Some of the agents are targeted for the disease-causing genetic variant, while others, although not targeted therapies, have implications for the disease they are used to treat. It is also possible that the disease implications of a genetic variant are unrelated to the pharmacogenomic implications. Some of these examples are considered clinically actionable pharmacogenes, with evidence-based, pharmacologic treatment recommendations, while others are still investigative as areas for additional research. It is important that clinicians are aware of both the disease and pharmacogenomic associations of these germline genetic variants to ensure patients are receiving comprehensive personalized care.

Phase Ib Pilot Study to Evaluate Reparixin in Combination with Weekly Paclitaxel in Patients with HER-2-Negative Metastatic Breast Cancer

Purpose: Chemokine receptor 1 (CXCR1) is recognized as an actionable receptor selectively expressed by breast cancer stem cells (BCSCs). Reparixin is an investigational allosteric inhibitor of chemokine receptors 1 and 2 (CXCR1/2), and demonstrates activity against BCSCs in human breast cancer xenografts. This phase Ib clinical trial examined dose, safety, and pharmacokinetics of paclitaxel plus reparixin therapy, and explored effects of reparixin on BCSCs in patients with metastatic breast cancer (MBC) (trial registration ID: NCT02001974).Experimental Design: Eligible patients had MBC and were candidates for paclitaxel therapy. Study treatment included a 3-day run-in with reparixin oral tablets three times a day, followed by paclitaxel 80 mg/m2/week (days 1, 8, and 15 for 28-day cycle) + reparixin tablets three times a day for 21/28 days; three dose cohorts were examined in a 3+3 dose escalation schema. Additional patients were recruited into an expansion cohort at the recommended phase II dose to further explore pharmacokinetics, safety, and biological effects of the combination therapy.Results: There were neither G4-5 adverse events nor serious adverse events related to study therapy and no interactions between reparixin and paclitaxel to influence their respective pharmacokinetic profiles. A 30% response rate was recorded, with durable responses >12 months in two patients. Exploratory biomarker analysis was inconclusive for therapy effect on BCSCs.Conclusions: Weekly paclitaxel plus reparixin in MBC appeared to be safe and tolerable, with demonstrated responses in the enrolled population. Dose level 3, 1200 mg orally three times a day, was selected for further study in a randomized phase II trial (NCT02370238). Clin Cancer Res; 23(18); 5358-65. ©2017 AACR.

Kinetic-Pharmacodynamic Model of Chemotherapy-Induced Peripheral Neuropathy in Patients with Metastatic Breast Cancer Treated with Paclitaxel, Nab-Paclitaxel, or Ixabepilone: CALGB 40502 (Alliance)

Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting toxicity caused by several chemotherapeutic agents. Currently, CIPN is managed by empirical dose modifications at the discretion of the treating physician. The goal of this research is to quantitate the dose-CIPN relationship to inform the optimal strategies for dose modification. Data were obtained from the Cancer and Leukemia Group B (CALGB) 40502 trial, a randomized phase III trial of paclitaxel vs. nab-paclitaxel vs. ixabepilone as first-line chemotherapy for locally recurrent or metastatic breast cancer. CIPN was measured using a subset of the Functional Assessment of Cancer Therapy-Gynecologic Oncology Group Neurotoxicity (FACT-GOG-NTX) scale. A kinetic-pharmacodynamic (K-PD) model was utilized to quantitate the dose-CIPN relationship simultaneously for the three drugs. Indirect response models with linear and Smax drug effects were evaluated. The model was evaluated by comparing the predicted proportion of patients with CIPN (score ≥8 or score ≥12) to the observed proportion. An indirect response model with linear drug effect was able to describe the longitudinal CIPN data reasonably well. The proportion of patients that were falsely predicted to have CIPN or were falsely predicted not to have CIPN was 20% or less at any cycle. The model will be utilized to identify an early time point that can predict CIPN at later time points. This strategy will be utilized to inform dose adjustments to prospectively manage CIPN. Clinicaltrials.gov ID: NCT00785291.

Association of CYP3A5 Expression and Vincristine Neurotoxicity in Pediatric Malignancies in Turkish Population

Vincristine is a widely used chemotherapeutic agent in the treatment of childhood malignancies. Neuropathy is the most common adverse effect. CYP3A4 and CYP3A5 enzymes of cytochrome p450 enzyme system are responsible in vincristine metabolism. Genetic polymorphism may alter the vincristine metabolism and the neurotoxicity rate. In this study, distribution of CYP3A5 alleles among Turkish children with malignancies, relation between CYP3A5 genotype and neurotoxicity rates, as well as severity and duration of neuropathy and total vincristine doses were investigated. Patient group consisted of 115 patients (age, 1 to 17 y) with acute lymphoblastic leukemia and solid tumors, who were treated with vincristine consisting chemotherapy protocols. Control group consisted of 50 children without any neurological symptom or disorders. All patient files were reviewed for presence and severeness of neurotoxicity symptoms. Blood samples were obtained and CYP3A5 genotypes were analyzed. Neurotoxicity occurred in 20.8% of patients. Although it was found to occur more frequently after 4 doses of vincristine, and rates were higher in the low-dose vincristine group suggesting other contributing factors. Although neurotoxicity rate in the CYP3A5*1/*3 genotype was 17.6%, it was 21.6% in the CYP3A5*3/*3 genotype and the difference was not statistically significant (P<0.05). This study suggested that vincristine-related neurotoxicity is dose-independent and genotype is not the only causative factor in the occurrence of neurotoxicity in these patients.

Prophylactic Administration of Aucubin Inhibits Paclitaxel-Induced Mechanical Allodynia via the Inhibition of Endoplasmic Reticulum Stress in Peripheral Schwann Cells

Paclitaxel is a chemotherapeutic agent that causes peripheral neuropathy as its major dose-limiting side effect. However, the peripheral neuropathy is difficult to manage. A study we recently conducted showed that repetitive administration of aucubin as a prophylactic inhibits paclitaxel-induced mechanical allodynia. However, the mechanisms underlying the anti-allodynic activity of aucubin, which is a major component of Plantaginis Semen, was unclear. In addition to mechanical allodynia, aucubin inhibited spontaneous and mechanical stimuli-induced firing in spinal dorsal horn neurons; however, catalpol, a metabolite of aucubin, did not show these effects. Furthermore, paclitaxel induced the expression of CCAAT/enhancer-binding protein homologous protein, a marker of endoplasmic reticulum (ER) stress, in the sciatic nerve and a Schwann cell line (LY-PPB6 cells); however, this effect was inhibited by aucubin. These results suggest that aucubin inhibits paclitaxel-induced mechanical allodynia through the inhibition of ER stress in peripheral Schwann cells.

Involvement of Charcot-Marie-Tooth disease gene mitofusin 2 expression in paclitaxel-induced mechanical allodynia in rats

Paclitaxel induces peripheral neuropathy, which is dose-limiting and results in loss of quality of life. Therefore, the prevention and treatment of paclitaxel-induced peripheral neuropathy are major concerns in clinical cancer therapy. However, the detailed mechanisms have not been fully elucidated. It has recently been reported that allelic variability in the Charcot-Marie-Tooth disease (CMT) genes, mitofusin 2 (MFN2), Rho guanine nucleotide exchange factor 10 (ARHGEF10), and periaxin (PRX), affected paclitaxel-induced peripheral neuropathy in clinical cases. Therefore, we hypothesized that paclitaxel may induce peripheral neuropathy due to changes in Mfn2, Arhgef10, and Prx mRNA expression. Paclitaxel (6mg/kg) was administered intraperitoneally, on two consecutive days per week for 4 weeks in rats. Paclitaxel-induced peripheral neuropathy was measured by the von Frey test and acetone test, mechanical allodynia, and cold hyperalgesia, respectively, on days 0, 3, 10, 17, and 24. Mfn2, Arhgef10, and Prx mRNA expression in the spinal cord were analyzed by qRT-PCR on days 3 and 24. Paclitaxel induced mechanical allodynia from days 17-24, but did not induce cold hyperalgesia. In addition, paclitaxel reduced Mfn2 mRNA expression, but not Arhgef10 or Prx mRNA expression, on days 3 and 24. In addition, Mfn2 mRNA level was decreased before the appearance of mechanical allodynia. The results of the present study suggest that a reduction in Mfn2 mRNA expression contributes to paclitaxel-induced mechanical allodynia.

Chemotherapy-induced peripheral neuropathy: A current review

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting side effect experienced by patients receiving treatment for cancer. Approximately 30 to 40% of patients treated with neurotoxic chemotherapy will develop CIPN, and there is considerable variability in its severity between patients. It is often sensory-predominant with pain and can lead to long-term morbidity in survivors. The prevalence and burden of CIPN late effects will likely increase as cancer survival rates continue to improve. In this review, we discuss the approach to peripheral neuropathy in patients with cancer and address the clinical phenotypes and pathomechanisms of specific neurotoxic chemotherapeutic agents. Ann Neurol 2017;81:772-781.

Eribulin alone or in combination with the PLK1 inhibitor BI 6727 triggers intrinsic apoptosis in Ewing sarcoma cell lines

In this study, we investigated the molecular mechanisms of eribulin-induced cell death and its therapeutic potential in combination with the PLK1 inhibitor BI 6727 in Ewing sarcoma (ES). Here, we show that eribulin triggers cell death in a dose-dependent manner in a panel of ES cell lines. In addition, eribulin at subtoxic, low nanomolar concentrations acts in concert with BI 6727 to induce cell death and to suppress long-term clonogenic survival. Mechanistic studies reveal that eribulin monotherapy at cytotoxic concentrations and co-treatment with eribulin at subtoxic concentrations together with BI 6727 arrest cells in the M phase of the cell cycle prior to the onset of cell death. This mitotic arrest is followed by increased phosphorylation of BCL-2 and BCL-x_L as well as downregulation of MCL-1, suggesting inactivation of these antiapoptotic BCL-2 family proteins. Consistently, eribulin monotherapy and eribulin/BI 6727 co-treatment trigger activation of BAX, a key proapoptotic BCL-2 family protein, and increase proteolytic activation of caspase-9 and -3. Importantly, overexpression of BCL-2 or addition of the broad-range caspase inhibitor zVAD.fmk significantly rescue eribulin- as well as eribulin/BI 6727-induced cell death. Together, these findings demonstrate that eribulin induces cell death via the intrinsic pathway of apoptosis in ES cells, both alone at cytotoxic concentrations and in combination with BI 6727 at subtoxic concentrations. Thus, our study highlights the therapeutic potential of eribulin for the treatment of ES alone or in rational combination therapies.

Microtubule-Targeting Agents Eribulin and Paclitaxel Differentially Affect Neuronal Cell Bodies in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of anticancer treatment with microtubule-targeted agents (MTAs). The frequency of severe CIPN, which can be dose limiting and even life threatening, varies widely among different MTAs. For example, paclitaxel induces a higher frequency of severe CIPN than does eribulin. Different MTAs also possess distinct mechanisms of microtubule-targeted action. Recently, we demonstrated that paclitaxel and eribulin differentially affect sciatic nerve axons, with paclitaxel inducing more pronounced neurodegenerative effects and eribulin inducing greater microtubule stabilizing biochemical effects. Here, we complement and extend these axonal studies by assessing the effects of paclitaxel and eribulin in the cell bodies of sciatic nerve axons, housed in the dorsal root ganglia (DRG). Importantly, the microtubule network in cell bodies is known to be significantly more dynamic than in axons. Paclitaxel induced activating transcription factor 3 expression, a marker of neuronal stress/injury. Paclitaxel also increased expression levels of acetylated tubulin and end binding protein 1, markers of microtubule stability and growth, respectively. These effects are hypothesized to be detrimental to the dynamic microtubule network within the cell bodies. In contrast, eribulin had no significant effect on any of these parameters in the cell bodies. Taken together, DRG cell bodies and their axons, two distinct neuronal cell compartments, contain functionally distinct microtubule networks that exhibit unique biochemical responses to different MTA treatments. We hypothesize that these distinct mechanistic actions may underlie the variability seen in the initiation, progression, persistence, and recovery from CIPN.

Use of an alpha lipoic, methylsulfonylmethane and bromelain dietary supplement (Opera®) for chemotherapy-induced peripheral neuropathy management, a prospective study

Chemotherapy-induced peripheral neuropathy (CIPN) is a major clinical problem associated with a number of cytotoxic agents. OPERA^® (GAMFARMA srl, Milan, Italy) is a new dietary supplement where α-lipoic acid, Boswellia Serrata, methylsulfonylmethane and bromelain are combined in a single capsule. The aim of this prospective study was to determine the efficacy and safety of OPERA^® supplementation in a series of patients affected by CIPN. We selected 25 subjects with CIPN evolving during or after chemotherapy with potentially neurotoxic agents. Patients were enrolled at the first clinical manifestation of neuropathy. CIPN was assessed at the enrollment visit and subsequently repeated every 3 weeks until 12 weeks. Primary endpoint was the evaluation of changes of measured scores after 12 weeks of therapy compared to baseline evaluation. Secondary endpoints were the evaluation of neuropathy reduction at 12 weeks after beginning of therapy with OPERA^®. Analysis of VAS data showed reduction in pain perceived by patients. According to NCI-CTC sensor and motor score, mISS scale and TNSc scale, both pain and both sensor and motor neuropathic impairment decreased after 12 weeks of treatments. Treatment with OPERA supplement was well tolerated; no increase in the toxicity profile of any of the therapeutic regimen that the patients were undergoing was reported. OPERA^® was able to improve CIPN symptoms in a prospective series of patients treated with neurotoxic chemotherapy, with no significant toxicity or interaction. Prospective RCT in a selected patients' population is warranted to confirm its promising activity.

Peripheral neuropathy with microtubule inhibitor containing antibody drug conjugates: Challenges and perspectives in translatability from nonclinical toxicology studies to the clinic

Antibody drug conjugates (ADC) consist of potent cytotoxic drugs conjugated to antibodies via chemical linkers, which enables specific targeting of tumor cells while reducing systemic exposure to the cytotoxic drug and improving the therapeutic window. The valine citrulline monomethyl auristatin E (vcMMAE, conventional linker-drug) ADC platform has shown promising clinical activity in several cancers, but peripheral neuropathy (PN) is a frequent adverse event leading to treatment discontinuation and dose reduction. This was not predicted based on nonclinical toxicology studies in monkeys or rats treated with vcMMAE ADCs. We evaluated four hypotheses for the lack of translatability of PN with vcMMAE ADCs: 1) species differences in exposure; 2) insensitivity of animal models; 3) species differences in target biology and other vcMMAE ADC properties in peripheral nerves and 4) increased susceptibility of patient population. The result of this hypothesis-based approach identified opportunities to improve the predictivity of PN in our animal models by increasing duration of exposure and adding an expanded neurohistopathology assessment of peripheral nerves. The utility of a predictive animal model would be to provide possible mitigation strategies in the clinic with vcMMAE ADCs and help to screen the next generation microtubule inhibitor (MTI) ADCs for reduced PN.

Prophylactic administration of an extract from Plantaginis Semen and its major component aucubin inhibits mechanical allodynia caused by paclitaxel in mice

The chemotherapeutic agent paclitaxel (PTX) causes peripheral neuropathy as a major dose-limiting side effect, and this peripheral neuropathy is difficult to control. Our previous report showed that prophylactic repetitive administration of goshajinkigan ( niú chē shèn qì wán), but not hachimijiogan ( bā wèi dì huáng wán), which lacks two of the constituents of goshajinkigan, inhibited PTX-induced mechanical allodynia in mice. Thus, the herbal medicines Plantaginis Semen ( chē qián zǐ) or Achyranthis Radix ( niú xī) may contribute to the inhibitory action of goshajinkigan on the exacerbation of PTX-induced mechanical allodynia [Andoh et al, J. Tradit. Complement. Med. 2014; 4: 293-297]. Therefore, in this study, we examined whether an extract of Plantaginis Semen (EPS) or Achyranthis Radix (EAR) would relieve PTX-induced mechanical allodynia in mice. A single intraperitoneal injection of PTX caused mechanical allodynia, which peaked on day 14 after injection. Repetitive oral administration of EPS, but not EAR, starting from the day after PTX injection significantly inhibited the exacerbation of PTX-induced mechanical allodynia. Repetitive intraperitoneal injection of aucubin, one of the main components of EPS, starting from the day after PTX injection also significantly reduced PTX-induced mechanical allodynia. However, repetitive intraperitoneal injection of geniposide acid (a precursor of aucubin) or catalpol (a metabolite of aucubin) did not prevent the exacerbation of mechanical allodynia. These results suggest that prophylactic administration of EPS is effective for preventing the exacerbation of PTX-induced allodynia. Aucubin may contribute to the inhibitory action of EPS on the exacerbation of PTX-induced allodynia.

Sustained Accumulation of Microtubule-Binding Chemotherapy Drugs in the Peripheral Nervous System: Correlations with Time Course and Neurotoxic Severity

Chemotherapy-induced peripheral neuropathy is a dose-limiting side effect of many antineoplastic agents, but the mechanisms underlying the toxicities are unclear. At their MTDs, the microtubule-binding drugs paclitaxel and ixabepilone induce more severe neuropathy in mice relative to eribulin mesylate, paralleling their toxicity profiles in clinic. We hypothesized that the severity of their neurotoxic effects might be explained by the levels at which they accumulate in the peripheral nervous system. To test this hypothesis, we compared their pharmacokinetics and distribution in peripheral nerve tissue. After administration of a single intravenous dose, each drug was rapidly cleared from plasma but all persisted in the dorsal root ganglia (DRG) and sciatic nerve (SN) for up to 72 hours. Focusing on paclitaxel and eribulin, we performed a 2-week MTD-dosing regimen, followed by a determination of drug pharmacokinetics, tissue distribution, and multiple functional measures of peripheral nerve toxicity for 4 weeks. Consistent with the acute dosing study, both drugs persisted in peripheral nervous tissues for weeks, in contrast to their rapid clearance from plasma. Notably, although eribulin exhibited greater DRG and SN penetration than paclitaxel, the neurotoxicity observed functionally was consistently more severe with paclitaxel. Overall, our results argue that sustained exposure of microtubule-binding chemotherapeutic agents in peripheral nerve tissues cannot by itself account for their associated neurotoxicity. Cancer Res; 76(11); 3332-9. ©2016 AACR.

Randomized sham-controlled pilot trial of weekly electro-acupuncture for the prevention of taxane-induced peripheral neuropathy in women with early stage breast cancer

To investigate the effect of electro-acupuncture (EA) as a non-pharmacological intervention to prevent or reduce chemotherapy-induced peripheral neuropathy (CIPN) in breast cancer patients undergoing chemotherapy of taxane. Women with stage I-III breast cancer scheduled to receive taxane therapy were randomized to receive a standardized protocol of 12 true or sham EA (SEA) weekly treatments concurrent with taxane treatment. Subjects completed the Brief Pain Inventory-Short Form (BPI-SF), Functional Assessment of Cancer Therapy-Taxane neurotoxicity subscale (FACT-NTX), and other assessments at baseline and weeks 6, 12, and 16. A total of 180 subjects were screened, 63 enrolled and 48 completed week 16 assessments. Mean age was 50 with 25 % white, 25 % black, and 43 % Hispanic; 52 % had no prior chemotherapy. At week 12, both groups reported an increase in mean BPI-SF worst pain score, but no mean differences were found between groups (SEA 2.8 vs. EA 2.6, P = .86). By week 16, the SEA group returned to baseline, while the EA group continued to worsen (SEA 1.7 vs. EA 3.4, P = .03). The increase in BPI-SF worst pain score was 1.62 points higher in the EA group than in the SEA group at week 16 (P = .04). In a randomized, sham-controlled trial of EA for prevention of taxane-induced CIPN, there were no differences in pain or neuropathy between groups at week 12. Of concern, subjects on EA had a slower recovery than SEA subjects. Future studies should focus on EA for treatment as opposed to prevention of CIPN.

Patient Management with Eribulin in Metastatic Breast Cancer: A Clinical Practice Guide

Eribulin, an antimicrotubule chemotherapeutic agent, is approved for the treatment of pretreated metastatic breast cancer (mBC) based on the positive outcomes of phase II and phase III clinical trials, which enrolled mainly Western patients. Eribulin has recently been approved in an increasing number of Asian countries; however, there is limited clinical experience in using the drug in certain countries. Therefore, we established an Asian working group to provide practical guidance for eribulin use based on our clinical experience. This paper summarizes the key clinical trials, and the management recommendations for the reported adverse events (AEs) of eribulin in mBC treatment, with an emphasis on those that are relevant to Asian patients, followed by further elaboration of our eribulin clinical experience. It is anticipated that this clinical practice guide will improve the management of AEs resulting from eribulin treatment, which will ensure that patients receive the maximum treatment benefit.

Volasertib Versus Chemotherapy in Platinum-Resistant or -Refractory Ovarian Cancer: A Randomized Phase II Groupe des Investigateurs Nationaux pour l'Etude des Cancers de l'Ovaire Study

PURPOSE

Volasertib is a potent and selective cell-cycle kinase inhibitor that induces mitotic arrest and apoptosis by targeting Polo-like kinase. This phase II trial evaluated volasertib or single-agent chemotherapy in patients with platinum-resistant or -refractory ovarian cancer who experienced failure after treatment with two or three therapy lines.

PATIENTS AND METHODS

Patients were randomly assigned to receive either volasertib 300 mg by intravenous infusion every 3 weeks or an investigator's choice of single-agent, nonplatinum, cytotoxic chemotherapy. The primary end point was 24-week disease control rate. Secondary end points included best overall response, progression-free survival (PFS), safety, quality of life, and exploratory biomarker analyses.

RESULTS

Of the 109 patients receiving treatment, 54 received volasertib and 55 received chemotherapy; demographics were well balanced. The 24-week disease control rates for volasertib and chemotherapy were 30.6% (95% CI, 18.0% to 43.2%) and 43.1% (95% CI, 29.6% to 56.7%), respectively, with partial responses in seven (13.0%) and eight (14.5%) patients, respectively. Median PFS was 13.1 weeks and 20.6 weeks for volasertib and chemotherapy (hazard ratio, 1.01; 95% CI, 0.66 to 1.53). Six patients (11%) receiving volasertib achieved PFS fore more than 1 year, whereas no patient receiving chemotherapy achieved PFS greater than 1 year. No relationship between the expression of the biomarkers tested and their response was determined. Patients treated with volasertib experienced more grade 3 and 4 drug-related hematologic adverse events (AEs) and fewer nonhematologic AEs than did patients receiving chemotherapy. Discontinuation resulting from AEs occurred in seven (13.0%) and 15 (27.3%) patients in the volasertib and chemotherapy arms, respectively. Both arms showed similar effects on quality of life.

CONCLUSION

Single-agent volasertib showed antitumor activity in patients with ovarian cancer. AEs in patients receiving volasertib were mainly hematologic and manageable.

Tumor-selective peptide-carrier delivery of Paclitaxel increases in vivo activity of the drug

Taxanes are highly effective chemotherapeutic drugs against proliferating cancer and an established option in the standard treatment of ovarian and breast cancer. However, treatment with paclitaxel is associated with severe side effects, including sensory axonal neuropathy, and its poor solubility in water complicates its formulation. In this paper we report the in vitro and in vivo activity of a new form of paclitaxel, modified for conjugation with a tumor-selective tetrabranched peptide carrier (NT4). NT4 selectively targets tumor cells by binding to membrane sulfated glycosaminoglycans (GAG) and to endocytic receptors, like LRP1 and LRP6, which are established tumor markers. Biological activity of NT4-paclitaxel was tested in vitro on MDA-MB 231 and SKOV-3 cell lines, representing breast and ovarian cancer, respectively, and in vivo in an orthotopic mouse model of human breast cancer. Using in vivo bioluminescence imaging, we found that conjugation of paclitaxel with the NT4 peptide led to increased therapeutic activity of the drug in vivo. NT4-paclitaxel induced tumor regression, whereas treatment with unconjugated paclitaxel only produced a reduction in tumor growth. Moreover, unlike paclitaxel, NT4-paclitaxel is very hydrophilic, which may improve its pharmacokinetic profile and allow the use of less toxic dilution buffers, further decreasing its general chemotherapic toxicity.

Natural products and complementary therapies for chemotherapy-induced peripheral neuropathy: A systematic review

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious dose-limiting side-effect without any FDA-approved treatment option. Prior reviews focus mostly on pharmacological interventions, but nonpharmaceutical interventions have also been evaluated. A Web of Science and PubMed database search to identify relevant RCTs from January 2005 to May 2015 included the terms: CIPN, cancer; and supplements, vitamin E, goshajinkigan, kampo, acetyl-L-carnitine, carnitine, alpha-lipoic acid, omega-3, glutamine, or glutamate; or massage, acupuncture, mind-body practice, yoga, meditation, Tai-Chi, physical activity, or exercise. Of 1465 publications screened, 12 RCTs evaluated natural products and one evaluated electroacupuncture. Vitamin E may help prevent CIPN. L-Glutamine, goshajinkigan, and omega-3 are also promising. Acetyl-L-carnitine may worsen CIPN and alpha-lipoic acid activity is unknown. Electroacupuncture was not superior to placebo. No RCTs were published regarding other complementary therapies, although some studies mention positive incidental findings. Natural products and complementary therapies deserve further investigation, given the lack of effective CIPN interventions.

Eribulin in heavily pretreated metastatic breast cancer patients and clinical/biological feature correlations: impact on the practice

AIM

This multicenter study describes the effectiveness of eribulin in current practice.

PATIENTS & METHODS

In total, 78 patients with advanced metastatic breast cancer, previously treated with two or more chemotherapy lines were enrolled.

RESULTS

The median duration of response and disease stability were 7.5 (5.4-9.5) and 8.9 (6.2-11.6) months, respectively, with a clinical benefit (CB) at 6 months in 41% of patients. CB in visceral and nonvisceral metastases were 72.7 and 88.9%, respectively. Eribulin was active also in brain metastases, with 47% CB. The activity was shown in all biological subtypes. Toxicities were manageable.

CONCLUSION

Our study confirms the effectiveness of eribulin mesylate in the treatment of patients with metastatic breast cancer and two or more lines of chemotherapy, in particular in the good disease control at the different metastatic sites.

Preclinical Efficacy and Safety Assessment of an Antibody-Drug Conjugate Targeting the c-RET Proto-Oncogene for Breast Carcinoma

PURPOSE

The RET proto-oncogene has been implicated in breast cancer, and the studies herein describe the preclinical and safety assessment of an anti-RET antibody-drug conjugate (ADC) being developed for the treatment of breast cancer.

EXPERIMENTAL DESIGN

RET protein expression was analyzed in breast tumor samples using tissue microarrays. The fully human anti-RET antibody (Y078) was conjugated to the DM1 and DM4 derivatives of the potent cytotoxic agent maytansine using thioether and disulfide linkers, respectively. The resulting compounds, designated Y078-DM1 and Y078-DM4, were evaluated for antitumor activity using human breast cancer cell lines and established tumor xenograft models. A single-dose, 28-day, safety study of Y078-DM1 was performed in cynomolgus monkeys.

RESULTS

By immunohistochemistry, RET expression was detected in 57% of tumors (1,596 of 2,800 tumor sections) and was most common in HER2-positive and basal breast cancer subtypes. Potent in vitro cytotoxicity was achieved in human breast cancer cell lines that have expression levels comparable with those observed in breast cancer tissue samples. Dose-response studies in xenograft models demonstrated antitumor activity with both weekly and every-3-weeks dosing regimens. In cynomolgus monkeys, a single injection of Y078-DM1 demonstrated dose-dependent, reversible drug-mediated alterations in blood chemistry with evidence of on-target neuropathy.

CONCLUSIONS

RET is broadly expressed in breast cancer specimens and thus represents a potential therapeutic target; Y078-DM1 and Y078-DM4 demonstrated antitumor activity in preclinical models. Optimization of the dosing schedule or an alternate cytotoxic agent with a different mechanism of action may reduce the potential risk of neuropathy. Clin Cancer Res; 21(24); 5552-62. ©2015 AACR.

Mechanisms involved in the development of chemotherapy-induced neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating and painful condition seen in patients undergoing treatment with common agents such as vincristine, paclitaxel, oxaliplatin and bortezomib. The mechanisms of this condition are diverse, and include an array of molecular and cellular contributions. Current research implicates genetic predispositions to this condition, which then may influence cellular responses to chemotherapy. Processes found to be influenced during CIPN include increased expression of inflammatory mediators, primarily cytokines, which can create cascading effects in neurons and glia. Changes in ion channels and neurotransmission, as well as changes in intracellular signaling and structures have been implicated in CIPN. This review explores these issues and suggests considerations for future research.

Paclitaxel improves outcome from traumatic brain injury

Pharmacologic interventions for traumatic brain injury (TBI) hold promise to improve outcome. The purpose of this study was to determine if the microtubule stabilizing therapeutic paclitaxel used for more than 20 years in chemotherapy would improve outcome after TBI. We assessed neurological outcome in mice that received direct application of paclitaxel to brain injury from controlled cortical impact (CCI). Magnetic resonance imaging was used to assess injury-related morphological changes. Catwalk Gait analysis showed significant improvement in the paclitaxel group on a variety of parameters compared to the saline group. MRI analysis revealed that paclitaxel treatment resulted in significantly reduced edema volume at site-of-injury (11.92 ± 3.0 and 8.86 ± 2.2mm(3) for saline vs. paclitaxel respectively, as determined by T2-weighted analysis; p ≤ 0.05), and significantly increased myelin tissue preservation (9.45 ± 0.4 vs. 8.95 ± 0.3, p ≤ 0.05). Our findings indicate that paclitaxel treatment resulted in improvement of neurological outcome and MR imaging biomarkers of injury. These results could have a significant impact on therapeutic developments to treat traumatic brain injury.

Taxane induced neuropathy in patients affected by breast cancer: Literature review

Taxane induced neuropathy (TIN) is the most limiting side effect of taxane based chemotherapy, relative to the majority of breast cancer patients undergoing therapy with both docetaxel and paclitaxel. The symptoms begin symmetrically from the toes, because the tips of the longest nerves are affected for first. The patients report sensory symptoms such as paresthesia, dysesthesia, numbness, electric shock-like sensation, motor impairment and neuropathic pain. There is a great inter-individual variability among breast cancer women treated with taxanes, in fact 20-30% of them don't develop neurotoxicity. Actually, there is no standard therapy for TIN, although many medications, antioxidants and natural substances have been tested in vitro and in vivo. We will summarize all most recent literature data on TIN prevention and treatment, in order to reach an improvement in TIN management. Further studies are needed to evaluate new therapies that restore neuronal function and improve life quality of patients.

Neurotoxicity in ovarian cancer patients on Gynecologic Oncology Group (GOG) protocol 218: characteristics associated with toxicity and the effect of substitution with docetaxel: an NRG Oncology/Gynecologic Oncology Group study

OBJECTIVES

To describe characteristics associated with neurotoxicity (NT) in advanced ovarian cancer patients treated on Gynecologic Oncology Group 218 and examine effect of substituting docetaxel for paclitaxel in these patients.

METHODS

The development of NT was defined as Common Toxicity Criteria grade (G)≥1. The association between substitution with docetaxel and NT improvement was explored with generalized estimating equations adjusting for treatment cycle and NT grading at previous cycle.

RESULTS

Of 1864 evaluable patients, 1329 (71%) developed G≥1 NT during the study. Nearly half appeared within the first two cycles of chemotherapy, with 31% experiencing G≥2. Older patients or those with worse quality of life (QoL) scores at baseline (p<0.05) were more likely to experience NT. One-hundred-six patients received docetaxel as substitute for paclitaxel. Of them, 47 patients started with docetaxel at cycle one due to reaction to paclitaxel (n=32), fear of NT (n=4), and other reasons (n=11), whereas 59 patients switched to docetaxel during cycle 2-6 due to NT (n=32), reaction to paclitaxel (n=19), and other reasons (n=8). Although the protocol instructed otherwise, the majority continued paclitaxel despite G≥2 NT symptoms. There was no evidence that substitution with docetaxel improved NT (Odds Ratio: 1.57; 95% CI 0.98-2.54; p>0.05). Of 59 patients who switched to docetaxel, only seven (12%) discontinued taxane prior to chemotherapy completion. A roughly equal chance of worsening NT was reported on paclitaxel (6%) as on docetaxel (5%).

CONCLUSIONS

Age and worse QoL at baseline are associated with NT. Substitution of docetaxel did not improve NT symptoms.

Synthesis, biological evaluation and mechanism study of chalcone analogues as novel anti-cancer agents

A series of novel chalcone analogues were designed, synthesized and evaluated as anticancer agents.

Microtubule-Targeting Agents Enter the Central Nervous System (CNS): Double-edged Swords for Treating CNS Injury and Disease

Microtubules have been among the most successful targets in anticancer therapy and a large number of microtubule-targeting agents (MTAs) are in various stages of clinical development for the treatment of several malignancies. Given that injury and diseases in the central nervous system (CNS) are accompanied by acute or chronic disruption of the structural integrity of neurons and that microtubules provide structural support for the nervous system at cellular and intracellular levels, microtubules are emerging as potential therapeutic targets for treating CNS disorders. It has been postulated that exogenous application of MTAs might prevent the breakdown or degradation of microtubules after injury or during neurodegeneration, which will thereby aid in preserving the structural integrity and function of the nervous system. Here we review recent evidence that supports this notion and also discuss potential risks of targeting microtubules as a therapy for treating nerve injury and neurodegenerative diseases.

Neurotoxicity as a prognostic factor in patients with metastatic breast cancer treated with ixabepilone as a first-line therapy

OBJECTIVE

This study is a longitudinal follow-up of metastatic breast cancer patients treated with ixabepilone as first-line chemotherapy, with the aim to evaluate the association between a mechanism-based neurotoxicity and the efficacy of ixabepilone.

PATIENTS AND METHODS

At the 2 main investigational sites of a phase II clinical trial, 50 patients previously treated with anthracycline received ixabepilone. A chart review was performed to evaluate overall survival (OS) and time to progression (TTP) and to describe the subsequent treatments.

RESULTS

The severe neurotoxicity induced by ixabepilone (38%) is correlated with a higher overall response rate to ixabepilone (79 vs. 48%; p = 0.042), a longer TTP (11.4 vs. 6.8 months; p = 0.023) and a longer OS (36.6 vs. 19.9 months; p = 0.05). After ixabepilone discontinuation, patients received a median of 4 subsequent chemotherapy lines (range 1-12). Among the 31 patients who received taxanes, neither the neurotoxicity incidence under treatment with taxanes nor the response was affected by a previous occurrence under ixabepilone treatment.

CONCLUSION

These findings suggest that neurotoxicity development under ixabepilone treatment is a predictor of treatment outcomes as well as a favorable prognostic factor. It highlights the risk-to-benefit ratio issue of ixabepilone. We noticed the possibility to treat patients with taxanes after ixabepilone without systematic recurrent neurotoxicity.

Effects of goshajinkigan, hachimijiogan, and rokumigan on mechanical allodynia induced by Paclitaxel in mice

Peripheral neuropathy is a major dose-limiting side effect of the chemotherapeutic agent paclitaxel. This study examined whether the three related traditional herbal formulations, goshajinkigan (GJG; 牛車腎氣丸 Niú Chē Shèn Qì Wán), hachimijiogan (HJG; 八味地黃丸 Bā Wèi Dì Huáng Wán), and rokumigan (RMG; 六味丸 Liù Wèi Wán), would relieve paclitaxel-induced mechanical allodynia in mice. A single intraperitoneal injection of paclitaxel (5 mg/kg) induced mechanical allodynia, which peaked on day 14 after injection. On day 14 after paclitaxel injection, oral administration of GJG (0.1-1.0 g/kg) produced a significant inhibition of established allodynia, but HJG and RMG did not affect the allodynia. Repeated oral administration of GJG (0.1-1.0 g/kg) starting from the day after paclitaxel injection did not affect allodynia development, but significantly inhibited allodynia exacerbation. Repeated oral administration of HJG produced a slight inhibition of allodynia exacerbation, but that of RMG did not. These results suggest that prophylactic administration of GJG is effective in preventing the exacerbation of paclitaxel-induced allodynia. The herbal medicines Plantaginis Semen (車前子 Chē Qián Zǐ) and Achyranthis Radix (牛膝 Niú Xī), which are present in GJG but not in HJG, may contribute to the inhibitory action of GJG on the exacerbation of paclitaxel-induced allodynia.

Ixabepilone-induced mitochondria and sensory axon loss in breast cancer patients

Background

We sought to define the clinical and ultrastructure effects of ixabepilone (Ix), a microtubule-stabilizing chemotherapy agent on cutaneous sensory nerves and to investigate a potential mitochondrial toxicity mechanism.

Methods

Ten breast cancer patients receiving Ix underwent total neuropathy score clinical (TNSc) assessment, distal leg skin biopsies at cycle (Cy) 3 (80–90 mg/m²), Cy5 (160–190 mg/m²), and Cy7 (>200 mg/m²) and were compared to 5 controls. Skin blocks were processed for EM and ultrastructural morphometry of Remak axons done.

Results

At baseline, Ix-treated subjects had higher TNSc values (4.5 ± 0.8 vs. 0.0 ± 0.0), greater percentage of empty (denervated) Schwann cells (29% vs. 12%), altered axonal diameter (422.9 ± 17 vs. 354.9 ± 14.8 nm, P = 0.01), and axon profiles without mitochondria tended to increase compared to control subjects (71% vs. 70%). With increasing cumulative Ix exposure, an increase in TNSc values (Cy3: 5.4 ± 1.2, Cy7: 10 ± 4, P < 0.001), empty Schwann cells (39% by Cy7), and dilated axons (in nm, Cy3: 506.3 ± 22.1, Cy5: 534.8 ± 33, Cy7: 527.8 ± 24.4; P < 0.001) was observed. In addition, axon profiles without mitochondria (Cy3:74%, Cy7:78%) and mitochondria with abnormal morphology (grade 3 or 4) increased from 24% to 79%. Schwann cells with atypical mitochondria and perineuronal macrophage infiltration in dermis were noted.

Interpretation

This study provides functional and structural evidence that Ix exposure induces a dose-dependent toxicity on small sensory fibers with an increase in TNSc scores and progressive axonal loss. Mitochondria appear to bear the cumulative toxic effect and chemotherapy-induced toxicity can be monitored through serial skin biopsy-based analysis.

Recovery sleep does not mitigate the effects of prior sleep loss on paclitaxel-induced mechanical hypersensitivity in Sprague-Dawley rats

Society has a rapidly growing accumulative sleep debt due to employment obligations and lifestyle choices that limit sleep opportunities. The degree to which poor sleep may set the stage for adverse symptom outcomes among more than 1.7 million persons who will be diagnosed with cancer is not entirely understood. Paclitaxel (PAC), a commonly used chemotherapy agent, is associated with painful, debilitating peripheral neuropathy of the hands and feet, which may persist long after adjuvant therapy is completed. The aims of this preclinical study were to determine the accumulative and sustained effects of sleep restriction on PAC-induced mechanical sensitivity in animals and whether there are male-female differences in mechanical sensitivity in PAC-injected animals. Sixty-two adult Sprague-Dawley rats (n = 31 females) were assigned to three cycles of intraperitoneal injections of PAC (1 mg/kg) versus vehicle (VEH; 1 ml/kg) every other day at light onset for 7 days, followed by seven drug-free days and to sleep restriction versus unperturbed sleep. Sleep restriction involved gentle handling to maintain wakefulness during the first 6 hr of lights on immediately following an injection; otherwise, sleep was unperturbed. Mechanical sensitivity was assessed via von Frey filaments, using the up-down method. Mechanical sensitivity data were Log10 transformed to meet the assumption of normality for repeated measures analysis of variance. Chronic sleep restriction of the PAC-injected animals resulted in significantly increased mechanical sensitivity that progressively worsened despite sleep recovery opportunities. If these relationships hold in humans, targeted sleep interventions employed during a PAC protocol may improve pain outcomes.

Integrated systems pharmacology analysis of clinical drug-induced peripheral neuropathy

A systems pharmacology approach was undertaken to define and identify the proteins/genes significantly associated with clinical incidence and severity of drug-induced peripheral neuropathy (DIPN). Pharmacological networks of 234 DIPN drugs, their known targets (both intended and unintended), and the intermediator proteins/genes interacting with these drugs via their known targets were examined. A permutation test identified 230 DIPN-associated intermediators that were enriched with apoptosis and stress response genes. Neuropathy incidence and severity were curated from drug labels and literature and were used to build a predictive model of DIPN using a regression tree algorithm, based on the drug targets and their intermediators. DIPN drugs whose targets interacted with both v-myc avian myelocytomatosis viral oncogene homolog (MYC) and proliferating cell nuclear antigen-associated factor (PAF15) were associated with a neuropathy incidence of 38.1%, whereas drugs interacting only with MYC had an incidence of 2.9%. These results warrant further investigation in order to develop a predictive tool for the DIPN potential of a new drug.

The marriage of quantitative genetics and cell biology: a novel screening approach reveals people have genetically encoded variation in microtubule stability

Microtubules play a central role in many essential cellular processes, including chromosome segregation, intracellular transport, and cell polarity. As these dynamic polymers are crucial components of eukaryotic cellular architecture, we were surprised by our recent discovery that a common human genetic difference leads to variation in microtubule stability in cells from different people. A single nucleotide polymorphism (SNP) near the TUBB6 gene, encoding class V β-tubulin, is associated with the expression level of this protein, which reduces microtubule stability at higher levels of expression. We discuss the novel cellular GWAS (genome-wide association study) platform that led to this discovery of natural, common variation in microtubule stability and the implications this finding may have for human health and disease, including cancer and neurological disorders. Furthermore, our generalizable approach provides a gateway for cell biologists to help interpret the functional consequences of human genetic variation.

Levo-tetrahydropalmatine attenuates oxaliplatin-induced mechanical hyperalgesia in mice

Common chemotherapeutic agents such as oxaliplatin often cause neuropathic pain during cancer treatment in patients. Such neuropathic pain is difficult to treat and responds poorly to common analgesics, which represents a challenging clinical issue. Corydalis yanhusuo is an old traditional Chinese medicine with demonstrated analgesic efficacy in humans. However, the potential analgesic effect of its active component, levo-tetrahydropalmatine (l-THP), has not been reported in conditions of neuropathic pain. This study found that l-THP (1–4 mg/kg, i.p.) produced a dose-dependent anti-hyperalgesic effect in a mouse model of chemotherapeutic agent oxaliplatin-induced neuropathic pain. In addition, we found that the anti-hyperalgesic effect of l-THP was significantly blocked by a dopamine D₁ receptor antagonist SCH23390 (0.02 mg/kg), suggesting a dopamine D₁ receptor mechanism. In contrast, l-THP did not significantly alter the general locomotor activity in mice at the dose that produced significant anti-hyperalgesic action. In summary, this study reported that l-THP possesses robust analgesic efficacy in mice with neuropathic pain and may be a useful analgesic in the management of neuropathic pain.