Staff, Nathan P.

AbstractPlatinum‐induced peripheral neurotoxicity (PIPN) is a common side effect of platinum‐based chemotherapy that may cause dose reduction and discontinuation, with oxaliplatin being more neurotoxic. PIPN includes acute neurotoxicity restricted to oxaliplatin, and chronic non‐length‐dependent sensory neuronopathy with positive and negative sensory symptoms and neuropathic pain in both upper and lower limbs. Chronic sensory axonal neuropathy manifesting as stocking‐and‐glove distribution is also frequent. Worsening of neuropathic symptoms after completing the last chemotherapy course may occur. Motor and autonomic involvement is uncommon. Ototoxicity is frequent in children and more commonly to cisplatin. Platinum‐based compounds result in more prolonged neuropathic symptoms in comparison to other chemotherapy agents. Patient reported outcomes questionnaires, clinical evaluation and instrumental tools offer complementary information in PIPN. Electrodiagnostic features include diffusely reduced/abolished sensory action potentials, in keeping with a sensory neuronopathy. PIPN is dependent on cumulative dose but there is a large variability in its occurrence. The search for additional risk factors for PIPN has thus far yielded no consistent findings. There are currently no neuroprotective strategies to reduce the risk of PIPN, and symptomatic treatment is limited to duloxetine that was found effective in a single phase III intervention study. This review critically examines the pathogenesis, incidence, risk factors (both clinical and pharmacogenetic), clinical phenotype and management of PIPN.

AbstractVinca alkaloids, thalidomide, and eribulin are widely used to treat patients with childhood acute lymphoblastic leukemia (ALL), adults affected by multiple myeloma and locally invasive or metastatic breast cancer, respectively. However, soon after their introduction into clinical practice, chemotherapy‐induced peripheral neurotoxicity (CIPN) emerged as their main non‐hematological and among dose‐limiting adverse events. It is generally perceived that vinca alkaloids and the antiangiogenic agent thalidomide are more neurotoxic, compared to eribulin. The exposure to these chemotherapeutic agents is associated with an axonal, length‐dependent, sensory polyneuropathy of mild to moderate severity, whereas it is considered that the peripheral nerve damage, unless severe, usually resolves soon after treatment discontinuation. Advanced age, high initial and prolonged dosing, coadministration of other neurotoxic chemotherapeutic agents and pre‐existing neuropathy are the common risk factors. Pharmacogenetic biomarkers might be used to define patients at increased susceptibility of CIPN. Currently, there is no established therapy for CIPN prevention or treatment; symptomatic treatment for neuropathic pain and dose reduction or withdrawal in severe cases is considered, at the cost of reduced cancer therapeutic efficacy. This review critically examines the pathogenesis, epidemiology, risk factors (both clinical and pharmacogenetic), clinical phenotype and management of CIPN as a result of exposure to vinca alkaloids, thalidomide and its analogue lenalidomide as also eribulin.

Abstract Chemotherapy‐induced peripheral neurotoxicity (CIPN) is a potentially dose‐limiting side effect of several commonly used cytotoxic chemotherapy agents. The main pharmacological classes that may cause CIPN include classical anticancer drugs, as well as the recently introduced immune checkpoint inhibitors and antibody drug conjugates. The absence of a complete knowledge of CIPN pathophysiology is only one of the several unsolved issues related to CIPN. Among some of the most relevant aspects of CIPN deserving further attention include the real number of patients exposed to the risk of CIPN, the long‐term impact on cancer survivors' quality of life due to incomplete recovery from CIPN, the economic burden related to acute and chronic CIPN, and the different perspective and education of the healthcare specialists in charge of managing patients with CIPN. Overall, CIPN remains a very challenging area of research as there are still several unresolved issues to be addressed in the future. In this special issue, the multifaceted profile of CIPN will be presented, with particular emphasis on bolstering the need to develop more optimized outcome measures than the existing ones to accurately evaluate the extent of CIPN, but also to ascertain the differences in the incidence, risk factors, clinical phenotype, and management of CIPN, according to the most commonly used neurotoxic chemotherapy classes. Perspectives for future research to pursue in order to cover the gaps in knowledge in the CIPN field will also be discussed.

AbstractObjectiveTo characterize the natural history and clinical features of myopathies caused by mono‐allelic, dominantly acting pathogenic variants in COL12A1.MethodsPatients with dominant COL12A1‐related myopathies were characterized by history and clinical examination, muscle imaging, and genetic analysis. Pathogenicity of the variants was assessed by immunostaining patient‐derived dermal fibroblast cultures for collagen XII.ResultsFour independent families with childhood‐onset weakness due to novel, dominantly acting pathogenic variants in COL12A1 were identified. Adult patients exhibited distal‐predominant weakness. Three families carried dominantly acting glycine missense variants, and one family had a heterozygous, intragenic, in‐frame deletion of exon 52 of COL12A1. All pathogenic variants resulted in increased intracellular retention of collagen XII in patient‐derived fibroblasts as well as loss of extracellular, fibrillar collagen XII deposition. Since haploinsufficiency for COL12A1 is largely clinically asymptomatic, we designed and evaluated small interfering RNAs (siRNAs) that specifically target the mutant allele containing the exon 52 deletion. Immunostaining of the patient fibroblasts treated with the siRNA showed a near complete correction of collagen XII staining patterns.InterpretationThis study characterizes a distal myopathy phenotype in adults with dominant COL12A1 pathogenic variants, further defining the phenotypic spectrum and natural history of COL12A1‐related myopathies. This work also provides proof of concept of a precision medicine treatment approach by proposing and validating allele‐specific knockdown using siRNAs specifically designed to target a patient’s dominant COL12A1 disease allele.

e23089 Background: Taxanes (paclitaxel and docetaxel) are commonly administered as part of chemotherapy for breast cancer, but long-term data on chemotherapy-induced peripheral neuropathy (CIPN) are limited in this population. We aimed to assess CIPN approximately three years after an initial exposure to paclitaxel or docetaxel. Methods: In a cross-sectional observation study, which surveyed consented enrollees annually after receipt of care at Mayo Clinic for a new breast cancer diagnosis over age 18, we collected patient-reported EORTC CIPN20 data by mailed questionnaire at baseline and three years after a breast cancer diagnosis. We then confirmed patient-reported chemotherapy data by chart abstraction and only included those who had received a standard course of docetaxel-based or paclitaxel-based chemotherapy, but had not had other neurotoxic treatment for cancer. CIPN20 overall and sensory scale raw scores were converted to a 0-100 linear scale with lower scores indicating more severe symptoms. Results: 84 women who received a taxane for breast cancer completed the survey. 82 were treated in the adjuvant or neo-adjuvant setting, while 2 received a taxane for metastatic breast cancer. 67 women received paclitaxel, while 17 received docetaxel. The median age at diagnosis was 51.5 years (range 31-86). 37 had estrogen receptor (ER) and/or progesterone receptor (PR) positive and human epidermal growth factor receptor-2 (Her2) negative, 31 Her2 positive, and 16 triple negative breast cancer. The median CIPN20 score was 92.98 (range 33.33-100). The median sensory CIPN score was 92.59 (range 25.94-100). 81% of women had an overall CIPN20 score of less than 100, and 68% had a sensory score of less than 100. Conclusions: The majority of women who received a taxane based chemotherapy regimen for breast cancer reported at least mild neuropathic symptoms three years out from treatment. Additional research is needed to help tailor chemotherapy decisions to toxicity risks and to reduce the likelihood of long-term CIPN, which can impair quality of life.

ABSTRACTIntroductionNeuropathy after total knee arthroplasty (TKA) can cause significant morbidity but is inconsistently reported.MethodsWe reviewed the clinical, electrodiagnostic and perioperative features of all patients who underwent primary TKA at our institution and developed a new neuropathy within 8 weeks postoperatively.ResultsFifty‐four cases were identified (incidence 0.37% [95% confidence interval, 0.28–0.49]) affecting the following nerve(s): peroneal (37), sciatic (11), ulnar (2), tibial (2), sural (1), and lumbosacral plexus (1). In all cases with follow‐up data, motor recovery typically occurred within 1 year and was complete or near‐complete.ConclusionsPost‐TKA neuropathy is uncommon, typically does not require intervention and usually resolves within 1 year. Post‐TKA neuropathy most often affects the nerves surgically at risk. Anesthesia type does not correlate with post‐TKA neuropathy. An inflammatory etiology for post‐TKA neuropathy is rare but should be considered in specific cases. Muscle Nerve 59:679–682, 2019