Placebo and nocebo effects in the neurological practice

A novel technology for preparing the placebos of vortioxetine hydrobromide tablets using LCD 3D printing

This study aimed to describe the use of liquid crystal display (LCD) three-dimensional (3D) printing technology to prepare moulds for vortioxetine hydrobromide (VOR) tablet placebos and provide an economical, convenient, and flexible method for the small-batch preparation of special-shaped, scored, and coated placebo tablets. First, LCD 3D printing was used to generate different placebo moulds of VOR tablets based on VOR tablet digital models subtracted from the digital models of cuboid moulds by Boolean operation to optimise the structures of moulds. The better placebo mould had a parting surface located at the 7/10 height of the packing cavities and the positioning columns and slots were three pairs, and the efflux space had slender efflux channels combined with wide efflux tanks. Next, the placebo mould was corrected by the dimensional compensation method due to the shrinkage rates of the packing cavities (2.42%) and placebo prescription (1.12%) and the thickness of the film coating (25.08 μm). The placebo prescription was 8% hydroxypropyl methylcellulose (SH K15M) hydroalcoholic gel, and its mass ratio to lactose was 0.8:2. The placebos were coated with 13% gastric-soluble film coating solution for 30 min and polished with the 30% PEG 4000 solution. The National Bureau of Standards value between the VOR tablets and their placebos was 1.22 ± 0.10 (less than1.5). Finally, the mass of the placebos was similar to that of the VOR tablets. Their dimensional differences were less than 0.1 mm. Their mass, colour, odour, shape, and texture were all similar, which were assessed by manual evaluation. In conclusion, the preparations of VOR tablet placebos can be applied in placebo-controlled trials, and LCD 3D printing has an extensive application value in preparing placebo tablets.

Stop testing for autoantibodies to the VGKC-complex: only request LGI1 and CASPR2

Autoantibodies to leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein like-2 (CASPR2) are associated with clinically distinctive syndromes that are highly immunotherapy responsive, such as limbic encephalitis, faciobrachial dystonic seizures, Morvan’s syndrome and neuromyotonia. These autoantibodies target surface-exposed domains of LGI1 or CASPR2, and appear to be directly pathogenic. In contrast, voltage-gated potassium channel (VGKC) antibodies that lack LGI1 or CASPR2 reactivities (‘double-negative’) are common in healthy controls and have no consistent associations with distinct syndromes. These antibodies target intracellular epitopes and lack pathogenic potential. Moreover, the clinically important LGI1 and CASPR2 antibodies comprise only ~15% of VGKC-positive results, meaning that most VGKC-antibody positive results mislead rather than help. Further, initial VGKC testing misses some cases that have LGI1 and CASPR2 antibodies. These collective observations confirm that laboratories should stop testing for VGKC antibodies and instead, test only for LGI1 and CASPR2 antibodies. This change in practice will lead to significant patient benefit.

Nocebo in Biosimilars and Generics in Neurology: A Systematic Review

Background: Nocebo refers to adverse events related to patients’ negative expectations and previous experiences, mediated by several neurobiological pathways within the brain. It is common among neurological patients and affects adherence and treatment outcomes, representing a real clinical challenge.

Methods: We conducted a systematic search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines in MEDLINE database, using several keywords for studies that can be processed to investigate the magnitude of nocebo in generics and biosimilars used in the most common neurological diseases. The aim was to estimate its size and suggest strategies to minimize its prevalence in clinical trials and practice.

Results: Of a total of 2,606 identified articles, after criteria-based selection, 35 studies were included for analysis. Overall, there was vast heterogeneity across the studies concerning population, study design, and outcomes. Nocebo response could be estimated only in one double-blind randomized trial of generic glatiramer acetate in relapsing remitting multiple sclerosis that included a placebo arm. In this trial, no significant differences observed between the three arms (innovator, bioequivalent, and placebo) in favorable and unfavorable outcomes. In the open-label phase of the trial, an increased withdrawal rate was recorded in patients switched from placebo to bioequivalent (8.4%) that may be related to nocebo. In other open-label and real-world studies evaluating biosimilars or generics for brain disorders, a similar indirect nocebo effect is assuming by several investigators. Also, knowledge gaps between health-care providers and patients exist towards generics and biosimilars.

Conclusions: Despite its presence, the true burden of the nocebo response and effect cannot be accurately estimated in existing studies with generics and biosimilars in neurological diseases. Targeted strategies for clinical trials’ design are needed in order to measure the exact nocebo’s size.

Minimizing nocebo effect: Pragmatic approach

The nocebo effect, the inverse of the placebo effect, is a well-established phenomenon, yet under-appreciated. It refers to nonpharmacological, harmful, or undesirable effects occurring after active or inactive therapy. The frequency of adverse events can dramatically increase by informing patients about the possible side effects of the treatment, and by negative expectations on the part of the patient. Patients who were told that they might experience sexual side effects after treatment with β-blocker drugs reported these symptoms between three and four times more often than patients in a control group who were not informed about these symptoms. Nocebo effect has been reported in several neurological diseases such as migraine, epilepsy, multiple sclerosis, Parkinson's disease and neuropathic pain, and in patients with depression. The investigation of the biological and theoretical underpinning of the nocebo phenomenon is at an early stage, and more research is required. Physicians need to be aware of the influence of nocebo phenomenon and be able to recognize it and minimize its effects.

Intracellular and non-neuronal targets of voltage-gated potassium channel complex antibodies

OBJECTIVES

Autoantibodies against the extracellular domains of the voltage-gated potassium channel (VGKC) complex proteins, leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-2 (CASPR2), are found in patients with limbic encephalitis, faciobrachial dystonic seizures, Morvan's syndrome and neuromyotonia. However, in routine testing, VGKC complex antibodies without LGI1 or CASPR2 reactivities (double-negative) are more common than LGI1 or CASPR2 specificities. Therefore, the target(s) and clinical associations of double-negative antibodies need to be determined.

METHODS

Sera (n=1131) from several clinically defined cohorts were tested for IgG radioimmunoprecipitation of radioiodinated α-dendrotoxin (¹²⁵I-αDTX)-labelled VGKC complexes from mammalian brain extracts. Positive samples were systematically tested for live hippocampal neuron reactivity, IgG precipitation of ¹²⁵I-αDTX and ¹²⁵I-αDTX-labelled Kv1 subunits, and by cell-based assays which expressed Kv1 subunits, LGI1 and CASPR2.

RESULTS

VGKC complex antibodies were found in 162 of 1131 (14%) sera. 90 of these (56%) had antibodies targeting the extracellular domains of LGI1 or CASPR2. Of the remaining 72 double-negative sera, 10 (14%) immunoprecipitated ¹²⁵I-αDTX itself, and 27 (38%) bound to solubilised co-expressed Kv1.1/1.2/1.6 subunits and/or Kv1.2 subunits alone, at levels proportionate to VGKC complex antibody levels (r=0.57, p=0.0017). The sera with LGI1 and CASPR2 antibodies immunoprecipitated neither preparation. None of the 27 Kv1-precipitating samples bound live hippocampal neurons or Kv1 extracellular domains, but 16 (59%) bound to permeabilised Kv1-expressing human embryonic kidney 293T cells. These intracellular Kv1 antibodies mainly associated with non-immune disease aetiologies, poor longitudinal clinical-serological correlations and a limited immunotherapy response.

CONCLUSIONS

Double-negative VGKC complex antibodies are often directed against cytosolic epitopes of Kv1 subunits and occasionally against non-mammalian αDTX. These antibodies should no longer be classified as neuronal-surface antibodies. They consequently lack pathogenic potential and do not in themselves support the use of immunotherapies.

Neuropathic Pain Treatment: Still a Challenge

Neuropathic pain (NP) is the result of a series of conditions caused by diseases or lesions to the somatosensory system. Due to the better understanding of NP pathophysiology previously unexplored therapies have been used with encouraging results. In this group, acetyl-L-carnitine, alpha-lipoic-acid, cannabinoids, clonidine, EMA401, botulinum toxin type A and new voltage-gated sodium channel blockers, can be included. Besides, changing paradigms may occur with the advent of optogenetics and a better understanding of epigenetic regulation. We reviewed the published literature on the pharmacological treatment of NP. Despite the interesting results, randomized controlled trials are demanded the majority of the therapies previously mentioned. In spite of several studies for the relief of NP, pain control continues being a challenge.