In vivo comparative study of the cytotoxicity of a liposomal formulation of cisplatin (lipoplatin™)

Role of Mouse Organic Cation Transporter 2 for Nephro- and Peripheral Neurotoxicity Induced by Chemotherapeutic Treatment with Cisplatin

Cisplatin (CDDP) is an efficient chemotherapeutic agent broadly used to treat solid cancers. Chemotherapy with CDDP can cause significant unwanted side effects such as renal toxicity and peripheral neurotoxicity. CDDP is a substrate of organic cation transporters (OCT), transporters that are highly expressed in renal tissue. Therefore, CDDP uptake by OCT may play a role in causing unwanted toxicities of CDDP anticancer treatment. In this study, the contribution of the mouse OCT2 (mOCT2) to CDDP nephro- and peripheral neurotoxicity was investigated by comparing the effects of cyclic treatment with low doses of CDDP on renal and neurological functions in wild-type (WT) mice and mice with genetic deletion of OCT2 (OCT2-/- mice). This CDDP treatment protocol caused significant impairment of kidneys and peripherical neurological functions in WT mice. These effects were significantly reduced in OCT2-/- mice, however, less profoundly than what was previously measured in mice with genetic deletion of both OCT1 and 2 (OCT1-2-/- mice). Comparing the apparent affinities (IC50) of mOCT1 and mOCT2 for CDDP, the mOCT1 displayed a higher affinity for CDDP than the mOCT2 (IC50: 9 and 558 µM, respectively). Also, cellular toxicity induced by incubation with 100 µM CDDP was more pronounced in cells stably expressing mOCT1 than in cells expressing mOCT2. Therefore, in mice, CDDP uptake by both OCT1 and 2 contributes to the development of CDDP undesired side effects. OCT seem to be suitable targets for establishing treatment protocols aimed at decreasing unwanted CDDP toxicity and improving anticancer treatment with CDDP.

Amino acid coordination complex mediates cisplatin entrapment within PEGylated liposome: An implication in colorectal cancer therapy

Cis-Diaminedichloroplatinum (cisplatin, CDDP) remained among the most widely used anti-cancer agents; however, management of the dose-limiting side effects is still a great hurdle to its therapeutic potential. In the framework of this investigation, novel approach was developed for CDDP encasement within liposome based on the formation of a coordination bond between the platinum (II) atom and a carboxylic group in aspartic acid (AA) and glutamic acid (GA). We have also compared two methods of preparation based on equilibration and conventional lipid film hydration. For this, first FTIR spectra of the conjugates confirmed coordination bond between Pt and the carboxylate moieties. The PEGylated liposomes composed of HSPC, cholesterol and DPPG had a size of 134 to 197 nm and negative zeta potential (-14.20 to -20.90 mv). Cytotoxicity study revealed IC₅₀ values of <7 µg/ml for liposomes. In vivo plasma retention following iv administration indicated the potential of liposome in maintaining cisplatin levels within the circulation, while free cisplatin and cisplatin conjugates were promptly eliminated. Anti-tumor efficacy studies following iv injections at 3 mg/kg cisplatin weekly for three weeks in C26 tumor bearing BALB/c mice demonstrated the potential of the cisplatin liposomes in tumor growth inhibition. Pt-complexes were not as effective as liposomal formulations showing the crucial role of liposomes in maintaining cisplatin levels within blood circulation. Overall, the developed cisplatin liposome seems to be a promising therapeutic approach for targeting solid tumors.

Translating morphology from bench side to bed side via neurophysiology: 8-min protocol for peripheral neuropathy research

BACKGROUND

Peripheral neuropathy treatment is not always satisfactory. To fill this gap, inferences from bench side are warranted, where morphological and pathogenetic determinations can be performed. Nerve conduction studies (NCS) are ideal to translate results from preclinical to clinical setting.

NEW METHODS

We propose a comprehensive 8-minute protocol for sensory-motor neurophysiological assessment, similar to routine clinical practice: sensory proximal and distal caudal nerves, motor caudal nerve, and sensory digital nerve recordings were used and tested in 2 different experimental settings. In Experiment 1 we compared control (CTRL) animals to a severe sensory-motor polyneuropathy (animals treated with vincristine [VCR]), and in Experiment 2 CTRL animals were compared to a mild sensory polyneuropathy (animals treated with oxaliplatin [OHP]). NCS were performed after 1-month of chemotherapy and matched with confirmatory neuropathological analyses.

RESULTS

VCR treated animals showed, at NCS, a relevant sensory-motor polyneuropathy ensued at the end of treatment; whereas, OHP animals showed a mild distal sensory neuropathy. These patterns were confirmed by neuropathological analysis.

COMPARISON WITH EXISTING METHODS

In literature, the majority of proposed neurophysiological protocols relies mainly on a single nerve testing, rather than a combination of them, and only a few studies tested both caudal and sciatic nerve branches, nevertheless not aiming at fully reproduce clinical protocols (e.g., seeking for length-dependency); to provide evidence of appropriateness of our protocol we applied a gold standard: neuropathology.

CONCLUSION

The simple and rapid protocol here presented can be suggested as a good translation outcome measure in preclinical setting.

Probing the peripheral immune response in mouse models of oxaliplatin-induced peripheral neuropathy highlights their limited translatability

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling side effect of various chemotherapeutic agents, including oxaliplatin. It is highly prevalent amongst cancer patients, causing sensory abnormalities and pain. Unfortunately, as the underlying mechanisms remain poorly understood, effective therapeutics are lacking. Neuro-immune interactions have been highlighted as potential contributors to the development and maintenance of CIPN, however, whether this is the case in oxaliplatin-induced peripheral neuropathy (OIPN) is yet to be fully established. Methods: In this study we used flow cytometry to examine the peripheral immune response of male C57BL/6 mice following both single and repeated oxaliplatin administration. In animals exposed to repeated dosing, we also undertook mechanical and thermal behavioural assays to investigate how oxaliplatin alters phenotype, and conducted RT-qPCR experiments on bone marrow derived macrophages in order to further inspect the effects of oxaliplatin on immune cells. Results: In contrast to other reports, we failed to observe substantial changes in overall leukocyte, lymphocyte or myeloid cell numbers in dorsal root ganglia, sciatic nerves or inguinal lymph nodes. We did however note subtle, tissue-dependant alterations in several myeloid subpopulations following repeated dosing. These included a significant reduction in MHCII antigen presenting cells in the sciatic nerve and an increase in infiltrating cell types into the inguinal lymph nodes. Though repeated oxaliplatin administration had a systemic effect, we were unable to detect a pain-like behavioural phenotype in response to either cold or mechanical stimuli. Consequently, we cannot comment on whether the observed myeloid changes are associated with OIPN. Conclusions: Our discussion puts these results into the wider context of the field, advocating for greater transparency in reporting, alignment in experimental design and the introduction of more clinically relevant models. Only through joint concerted effort can we hope to increase our understanding of the underlying mechanisms of CIPN, including any immune contributions.

Lipid, polymeric, inorganic-based drug delivery applications for platinum-based anticancer drugs

The three main FDA-approved platinum drugs in chemotherapy such as carboplatin, cisplatin, and oxaliplatin are extensively applied in cancer treatments. Although the clinical applications of platinum-based drugs are extremely effective, their toxicity profile restricts their extensive application. Therefore, recent studies focus on developing new platinum drug formulations, expanding the therapeutic aspect. In this sense, recent advances in the development of novel drug delivery carriers will help with the increase of drug stability and biodisponibility, concomitantly with the reduction of drug efflux and undesirable secondary toxic effects of platinum compounds. The present review describes the state of the art of platinum drugs with their biological effects, pre- and clinical studies, and novel drug delivery nanodevices based on lipids, polymers, and inorganic.

Probing the peripheral immune response in mouse models of oxaliplatin-induced peripheral neuropathy highlights their limited translatability

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling side effect of various chemotherapeutic agents, including oxaliplatin. It is highly prevalent amongst cancer patients, causing sensory abnormalities and pain. Unfortunately, as the underlying mechanisms remain poorly understood, effective therapeutics are lacking. Neuro-immune interactions have been highlighted as potential contributors to the development and maintenance of CIPN, however, whether this is the case in oxaliplatin-induced peripheral neuropathy (OIPN) is yet to be fully established. Methods: In this study we used flow cytometry to examine the peripheral immune response of male C57BL/6 mice following both single and repeated oxaliplatin administration. In animals exposed to repeated dosing, we also undertook mechanical and thermal behavioural assays to investigate how oxaliplatin alters phenotype, and conducted RT-qPCR experiments on bone marrow derived macrophages in order to further inspect the effects of oxaliplatin on immune cells. Results: In contrast to other reports, we failed to observe substantial changes in overall leukocyte, lymphocyte or myeloid cell numbers in dorsal root ganglia, sciatic nerves or inguinal lymph nodes. We did however note subtle, tissue-dependant alterations in several myeloid subpopulations following repeated dosing. These included a significant reduction in MHCII antigen presenting cells in the sciatic nerve and an increase in infiltrating cell types into the inguinal lymph nodes. Though repeated oxaliplatin administration had a systemic effect, we were unable to detect a pain-like behavioural phenotype in response to either cold or mechanical stimuli. Consequently, we cannot comment on whether the observed myeloid changes are associated with OIPN. Conclusions: Our discussion puts these results into the wider context of the field, advocating for greater transparency in reporting, alignment in experimental design and the introduction of more clinically relevant models. Only through joint concerted effort can we hope to increase our understanding of the underlying mechanisms of CIPN, including any immune contributions.

Liposomes Co-Encapsulating Cisplatin/Mifepristone Improve the Effect on Cervical Cancer: In Vitro and In Vivo Assessment

Cervical cancer is usually diagnosed in the later stages despite many campaigns for early detection and continues to be a major public health problem. The standard treatment is cisplatin-based chemotherapy plus radiotherapy, but patient response is far from ideal. In the research for new drugs that enhance the activity of cisplatin, different therapeutic agents have been tested, among them the antiprogestin mifepristone. Nevertheless, the efficacy of cisplatin is limited by its low specificity for tumor tissue, which causes severe side effects. Additionally, cervical tumors often become drug resistant. These problems could possibly be addressed by the use of liposome nanoparticles to encapsulate drugs and deliver them to the target. The aim of this study was to prepare liposome nanoparticles that co-encapsulate cisplatin and mifepristone, evaluate their cytotoxicity against HeLa cells and in vivo with subcutaneous inoculations of xenografts in nu/nu mice, and examine some plausible mechanisms of action. The liposomes were elaborated by the reverse-phase method and characterized by physicochemical tests. The nanoparticles had a mean particle size of 109 ± 5.4 nm and a Zeta potential of -38.7 ± 1.2 mV, the latter parameter indicating a stable formulation. These drug-loaded liposomes significantly decreased cell viability in vitro and tumor size in vivo, without generating systemic toxicity in the animals. There was evidence of cell cycle arrest and increased apoptosis. The promising results with the co-encapsulation of cisplatin/mifepristone warrant further research.

Pathogenesis of platinum-induced peripheral neurotoxicity: Insights from preclinical studies

One of the most relevant dose-limiting adverse effects of platinum drugs is the development of a sensory peripheral neuropathy that highly impairs the patients' quality of life. Nowadays there are no available efficacy strategies for the treatment of platinum-induced peripheral neurotoxicity (PIPN), and the only way to prevent its development and progression is by reducing the dose of the cytostatic drug or even withdrawing the chemotherapy regimen. This clinical issue has been the main focus of hundreds of preclinical research works during recent decades. As a consequence, dozens of in vitro and in vivo models of PIPN have been developed to elucidate the molecular mechanisms involved in its development and to find neuroprotective targets. The apoptosis of peripheral neurons has been identified as the main mechanism involved in PIPN pathogenesis. This mechanism of DRG sensory neurons cell death is triggered by the nuclear and mitochondrial DNA platination together with the increase of the oxidative cellular status induced by the depletion of cytoplasmic antioxidant mechanisms. However, since there has been no successful transfer of preclinical results to clinical practise in terms of therapeutic approaches, some mechanisms of PIPN pathogenesis still remain to be elucidated. This review is focused on the pathogenic mechanisms underlying PIPN described up to now, provided by the critical analysis of in vitro and in vivo models.

Pharmacokinetics of cisplatin during open and minimally-invasive secondary cytoreductive surgery plus HIPEC in women with platinum-sensitive recurrent ovarian cancer: a prospective study

Objective

Evidences from animal models seem to suggest that minimally invasive surgery may enhance cisplatin diffusion when the drug is administered in the context of post-operative hyperthermic intraperitoneal chemotherapy (HIPEC). The present study evaluates the cisplatin pharmacokinetic profile in a prospective series of women with platinum sensitive recurrent epithelial ovarian cancer treated with open secondary cytoreductive surgery (O-SCS) or minimally-invasive secondary cytoreductive surgery (MI-SCS).

Methods

Cisplatin levels were assessed at 0, 20, 40, 60, and 120 minutes in: 1) blood samples, 2) peritoneal perfusate, and 3) peritoneal biopsies at the end of HIPEC. Median C_max has been used to identify women with high and low drug levels. Progression-free survival (PFS) was calculated as the time elapsed between SCS+HIPEC and secondary recurrence or last follow-up visit.

Results

Nine (45.0%) women received MI-SCS, and 11 (55.0%) O-SCS. At 60 minutes, median cisplatin C_max in peritoneal tissue was higher in patients treated with MI-SCS compared to O-SCS (C_max=8.262 µg/mL vs. C_max=4.057 µg/mL). Furthermore, median cisplatin plasma C_max was higher in patients treated with MI-SCS compared to O-SCS (C_max=0.511 vs. C_max=0.254 µg/mL; p-value=0.012) at 120 minutes. With a median follow-up time of 24 months, women with higher cisplatin peritoneal C_max showed a longer PFS compared to women with low cisplatin peritoneal levels (2-years PFS=70% vs. 35%; p-value=0.054).

Conclusions

We demonstrate for the first time that minimally invasive route enhances cisplatin peritoneal tissue uptake during HIPEC, further evaluations are needed to confirm the correlation between peritoneal cisplatin levels after HIPEC and survival.

Trial Registration

ClinicalTrials.gov Identifier: NCT01539785

Polymer Nanovesicle-Mediated Delivery of MLN8237 Preferentially Inhibits Aurora Kinase A To Target RalA and Anchorage-Independent Growth in Breast Cancer Cells

The small GTPase RalA is a known mediator of anchorage-independent growth in cancers and is differentially regulated by adhesion and aurora kinase A (AURKA). Hence, inhibiting AURKA offers a means of specifically targeting RalA (over RalB) in cancer cells. MLN8237 (alisertib) is a known inhibitor of aurora kinases; its specificity for AURKA, however, is compromised by its poor solubility and transport across the cell membrane. A polymer nanovesicle platform is used for the first time to deliver and differentially inhibit AURKA in cancer cells. For this purpose, polysaccharide nanovesicles made from amphiphilic dextran were used as nanocarriers to successfully administer MLN8237 (V_MLN) in cancer cells in 2D and 3D microenvironments. These nanovesicles (<200 nm) carry the drug in their intermembrane space with up to 85% of it released by the action of esterase enzyme(s). Lysotracker experiments reveal the polymer nanovesicles localize in the lysosomal compartment of the cell, where they are enzymatically targeted and MLN released in a controlled manner. Rhodamine B fluorophore trapped in the nanovesicles hydrophilic core (V_MLN+RhB) allows us to visualize its uptake and localization in cells in a 2D and 3D microenvironment. In breast cancer, MCF-7 cells V_MLN inhibits AURKA significantly better than the free drug at low concentrations (0.02-0.04 μM). This ensures that the drug in V_MLN at these concentrations can specifically inhibit up to 94% of endogenous AURKA without affecting AURKB. This targeting of AURKA causes the downstream differential inhibition of active RalA (but not RalB). Free MLN8237 at similar concentrations and conditions failed to affect RalA activation. V_MLN-mediated inhibition of RalA, in turn, disrupts the anchorage-independent growth of MCF-7 cells supporting a role for the AURKA-RalA crosstalk in mediating the same. These studies not only identify the polysaccharide nanovesicle to be an improved way to efficiently deliver low concentrations of MLN8237 to inhibit AURKA but, in doing so, also help reveal a role for AURKA and its crosstalk with RalA in anchorage-independent growth of MCF-7 cells.

Susceptibility of different mouse strains to oxaliplatin peripheral neurotoxicity: Phenotypic and genotypic insights

Peripheral neurotoxicity is one of the most distressing side effects of oxaliplatin therapy for cancer. Indeed, most patients that received oxaliplatin experience acute and/or chronic severe sensory peripheral neuropathy. However, despite similar co-morbidities, cancer stage, demographics and treatment schedule, patients develop oxaliplatin-induced peripheral neurotoxicity with remarkably different severity. This suggests individual genetic variability, which might be used to glean the mechanistic insights into oxaliplatin neurotoxicity. We characterized the susceptibility of different mice strains to oxaliplatin neurotoxicity investigating the phenotypic features of neuropathy and gene expression profiles in dorsal root ganglia of six genetically different mice strains (Balb-c, C57BL6, DBA/2J, AJ, FVB and CD1) exposed to the same oxaliplatin schedule. Differential gene expression in dorsal root ganglia from each mice strain were assayed using a genome-wide expression analysis and selected genes were validated by RT-PCR analysis. The demonstration of consistent differences in the phenotypic response to oxaliplatin across different strains is interesting to allow the selection of the appropriate strain based on the pre-defined read-out parameters. Further investigation of the correlation between gene expression changes and oxaliplatin-induced neurotoxicity phenotype in each strain will be useful to deeper investigate the molecular mechanisms of oxaliplatin neurotoxicity.

Pharmacokinetics of concomitant cisplatin and paclitaxel administered by hyperthermic intraperitoneal chemotherapy to patients with peritoneal carcinomatosis from epithelial ovarian cancer

Background:

Hyperthermic intraperitoneal chemotherapy (HIPEC) is advised as a treatment option for epithelial ovarian cancer (EOC) with peritoneal carcinomatosis. This study was designed to define the pharmacokinetics of cisplatin (CDDP) and paclitaxel (PTX) administered together during HIPEC.

Methods:

Thirteen women with EOC underwent cytoreductive surgery (CRS) and HIPEC, with CDDP and PTX. Blood, peritoneal perfusate and tissue samples were harvested to determine drug exposure by high-performance liquid chromatography and matrix-assisted laser desorption ionization imaging mass spectrometry (IMS).

Results:

The mean maximum concentrations of CDDP and PTX in perfusate were, respectively, 24.8±10.4 μg ml⁻¹ and 69.8±14.3 μg ml⁻¹; in plasma were 1.87±0.4 μg ml⁻¹ and 0.055±0.009 μg ml⁻¹. The mean concentrations of CDDP and PTX in peritoneum at the end of HIPEC were 23.3±8.0 μg g⁻¹ and 30.1±18.3 μg⁻¹g⁻¹, respectively. The penetration of PTX into the peritoneal wall, determined by IMS, was about 0.5 mm. Grade 3–4 surgical complications were recorded in four patients, five patients presented grade 3 and two patients presented grade 4 hematological complications.

Conclusions:

HIPEC with CDDP and PTX after CRS is feasible with acceptable morbidity and has a favorable pharmacokinetic profile: high drug concentrations are achieved in peritoneal tissue with low systemic exposure. Larger studies are needed to demonstrate its efficacy in patients with microscopic postsurgical residual tumours in the peritoneal cavity.

A novel AMPK activator reduces glucose uptake and inhibits tumor progression in a mouse xenograft model of colorectal cancer

The anticancer activity of a novel pure 1,4-Diaryl-2-azetidinone (1), endowed with a higher solubility than the well known Combretastatin A4, is tested in mice. We previously reported that Compound (1) showed specific antiproliferative activity against duodenal and colon cancer cells, inducing activation of AMP-activated protein kinase and apoptosis. Here we estimate that the maximum tolerated dose in a mouse model is 40 mg/kg; the drug is well tolerated both in single dose and in repeated administration schedules. The drug displays a significant antitumor activity and a tumor growth delay when administered at the MTD both in single and fractionated i.v. administration in a mouse xenograft model of colorectal cancer. Arrest of tumor growth and relapse after drug suspension are parallel to modification in glucose demand as shown by PET studies with [(18)F] FDG. These data strongly support Compound (1) as a promising molecule for in vivo treatment of colorectal cancer.

Nanoscale drug delivery platforms overcome platinum-based resistance in cancer cells due to abnormal membrane protein trafficking

The development of cellular resistance to platinum-based chemotherapies is often associated with reduced intracellular platinum concentrations. In some models, this reduction is due to abnormal membrane protein trafficking, resulting in reduced uptake by transporters at the cell surface. Given the central role of platinum drugs in the clinic, it is critical to overcome cisplatin resistance by bypassing the plasma membrane barrier to significantly increase the intracellular cisplatin concentration enough to inhibit the proliferation of cisplatin-resistant cells. Therefore, rational design of appropriate nanoscale drug delivery platforms (nDDPs) loaded with cisplatin or other platinum analogues as payloads is a possible strategy to solve this problem. This review will focus on the known mechanism of membrane trafficking in cisplatin-resistant cells and the development and employment of nDDPs to improve cell uptake of cisplatin.

The effect of curcumin on oxaliplatin and cisplatin neurotoxicity in rats: some behavioral, biochemical, and histopathological studies

Cisplatin is commonly used against several solid tumors, and oxaliplatin is an effective cytotoxic drug used in colorectal cancer. A major clinical issue affecting 10-40 % of patients treated with cisplatin or oxaliplatin is severe peripheral neuropathy causing sensory, motor, and autonomic dysfunction, with symptoms including cold sensitivity and neuropathic pain. The biochemical basis of the neurotoxicity is uncertain, but is associated with oxidative stress. Curcumin (a natural phenolic yellow pigment) has strong antioxidant, anticancer, and anti-inflammatory actions. Here we report the possible protective effect of curcumin on some cisplatin- and oxaliplatin-induced behavioral, biochemical, and histopathological alterations in rats. Twenty-four hours after the end of treatments some motor and behavioral tests (motor activity, thermal and mechanical nociception, and neuromuscular coordination) were conducted, followed by measuring plasma neurotensin platinum concentration in the sciatic nerve, and studying the histopathology of the sciatic nerve. Oxaliplatin (4 mg/kg) and cisplatin (2 mg/kg) [each given twice weekly, in a total of nine intraperitoneal injections over 4.5 weeks] significantly increased plasma neurotensin concentration, caused specific damage in the histology of the sciatic nerve and produced variable effects in the motor and behavioral tests. Oral curcumin (10 mg/kg, 4 days before the platinum drug, and thereafter, concomitantly with it for 4.5 weeks) reversed the alterations in the plasma neurotensin and sciatic nerve platinum concentrations, and markedly improved sciatic nerve histology in the platinum-treated rats. Larger experiments using a wider dose range of oxaliplatin, cisplatin, and curcumin are required to fully elucidate the possible protective role of curcumin in platinum-induced neurotoxicity.

Mirtazapine protects against cisplatin-induced oxidative stress and DNA damage in the rat brain

AIM

Cisplatin chemotherapy is associated with neurotoxicity, and oxidative stress might play an important role in the pathogenesis. Mirtazapine may be a preventative agent via its less-known antioxidant properties. The aim of this study was to examine the potential chemoprotective effects of mirtazapine against cisplatin-induced oxidative stress and DNA damage.

METHODS

Twenty-four rats were divided equally into four groups: control; cisplatin (10 mg/kg i.p.); cisplatin plus mirtazapine (10-30 mg/kg, respectively i.p and p.o.); and mirtazapine (30 mg/kg p.o.). The rats were killed at the end of the 14th day of treatment. Brain tissue was examined with regard to antioxidant/oxidant biochemical parameters.

RESULTS

Although glutathione (tGSH) and nitric oxide (NO) end product mean scores were found to be statistically higher in the control group when compared with the cisplatin group (72.44% and 61.99% percentage change [PC], respectively), malondialdehyde (MDA), myeloperoxidase (MPO), and 8-hydroxyguanine (8-OH-GUA) mean scores were statistically lower in the control group in comparison with the cisplatin group (-55.48%, -67.99%, and -48.81% PC, respectively; P < 0.01). Finally, tGSH and NO end product levels were restored to normal (85.90% and 55.30% PC, respectively), and MDA, MPO, and 8-OH-GUA were significantly reduced by treatment with mirtazapine (-60.50%, -78.59%, and -38.10% PC, respectively; P < 0.01).

CONCLUSION

Mirtazapine has chemoprotective effects against cisplatin-induced oxidative stress and DNA damage in the rat brain, which may be attributed to its antioxidant capabilities. It would be useful to investigate whether cisplatin at the desired doses can be given concurrently with mirtazapine.

CR4056, a new analgesic I2 ligand, is highly effective against bortezomib-induced painful neuropathy in rats

Although bortezomib (BTZ) is the frontline treatment for multiple myeloma, its clinical use is limited by the occurrence of painful peripheral neuropathy, whose treatment is still an unmet clinical need. Previous studies have shown chronic BTZ administration (0.20 mg/kg intravenously three times a week for 8 weeks) to female Wistar rats induced a peripheral neuropathy similar to that observed in humans. In this animal model of BTZ-induced neurotoxicity, the present authors evaluated the efficacy of CR4056, a novel I2 ligand endowed with a remarkable efficacy in several animal pain models. CR4056 was administered in a wide range of doses (0.6-60 mg/kg by gavage every day for 2-3 weeks) in comparison with buprenorphine (Bupre) (28.8 μg/kg subcutaneously every day for 2 weeks) and gabapentin (Gaba) (100 mg/kg by gavage every day for 3 weeks). Chronic administration of BTZ reduced nerve conduction velocity and induced allodynia. CR4056, Bupre, or Gaba did not affect the impaired nerve conduction velocity. Conversely, CR4056 dose-dependently reversed BTZ-induced allodynia (minimum effective dose 0.6 mg/kg). The optimal dose found, 6 mg/kg, provided a constant pain relief throughout the treatment period and without rebound after suspension, being effective when coadministered with BTZ, starting before or after allodynia was established, or when administered alone after BTZ cessation. A certain degree of tolerance was seen after 7 days of administration, but only at the highest doses (20 and 60 mg/kg). Bupre was effective only acutely, since tolerance was evident from the fourth day onwards. Gaba showed a significant activity only at the fourth day of treatment. CR4056, over the range of concentrations of 3-30 μM, was unable to hinder BTZ cytotoxicity on several tumor cell lines, which could indicate that this substance does not directly interfere with BTZ antitumor activity. Therefore, CR4056 could represent a new treatment option for BTZ-induced neuropathic pain.