Results of a UK National Cancer Research Institute Phase II study of brentuximab vedotin using a response-adapted design in the first-line treatment of patients with classical Hodgkin lymphoma unsuitable for chemotherapy due to age, frailty or comorbidity (BREVITY).

Standard treatment for classical Hodgkin lymphoma (cHL) is poorly tolerated in older patients and results disappointing. We assessed safety and efficacy of brentuximab vedotin (BV), in previously untreated patients with cHL unfit for standard treatment due to age, frailty or comorbidity. The primary outcome was complete metabolic response (CMR) by positron emission tomography/computed tomography after four BV cycles (PET4). The secondary outcomes included progression-free survival (PFS), overall survival (OS), and toxicity. In all, 35 patients with a median age of 77 years and median total Cumulative Illness Rating Scale for Geriatrics (CIRS-G) score of 6 were evaluable for toxicity and 31 for response. A median of four cycles were given (range one-16). In all, 14 patients required dose reduction due to toxicity and 11 patients stopped treatment due to adverse events (AEs). A total of 716 AEs were reported, of which 626 (88%) were Grade 1/2 and 27 (77%) patients had at least one AE Grade ≥3. At PET4, CMR was 25·8% [95% confidence interval (CI) 13·7-42.2%] and objective response rate 83·9% (95% CI 63·7-90·8%). Median PFS was 7·3 months (95% CI 5·2-9·0), and OS 19·5 months. Our results suggest that BV monotherapy is tolerable but suboptimal in the front-line therapy of elderly or comorbid patients with cHL. Combining BV with other agents may be more effective. Trial Registration: Clinicaltrials.gov identifier: NCT02567851.

Botulinum toxin-A treatment reduces human mechanical pain sensitivity and mechanotransduction.

The mechanisms underlying the analgesic effects of botulinum toxin serotype A (BoNT-A) are not well understood. We have tested the hypothesis that BoNT-A can block nociceptor transduction. Intradermal administration of BoNT-A to healthy volunteers produced a marked and specific decrease in noxious mechanical pain sensitivity, whereas sensitivity to low-threshold mechanical and thermal stimuli was unchanged. BoNT-A did not affect cutaneous innervation. In cultured rodent primary sensory neurons, BoNT-A decreased the proportion of neurons expressing slowly adapting mechanically gated currents linked to mechanical pain transduction. Inhibition of mechanotransduction provides a novel locus of action of BoNT-A, further understanding of which may extend its use as an analgesic agent.

Connecting the developing preterm brain.

White matter injury and abnormal maturation are thought to be major contributors to the neurodevelopmental disabilities observed in children and adolescents who were born preterm. Early detection of abnormal white matter maturation is important in the design of preventive, protective, and rehabilitative strategies for the management of the preterm infant. Diffusion Tensor Imaging (DTI) allows non-invasive, in vivo visualization and quantification of white matter tracts and has become a valuable tool in assessing white matter maturation in children born preterm. We will review the use of DTI to study white matter maturation and injury in the preterm brain.

Genome-wide transcriptional profiling of skin and dorsal root ganglia after ultraviolet-B-induced inflammation.

Ultraviolet-B (UVB)-induced inflammation produces a dose-dependent mechanical and thermal hyperalgesia in both humans and rats, most likely via inflammatory mediators acting at the site of injury. Previous work has shown that the gene expression of cytokines and chemokines is positively correlated between species and that these factors can contribute to UVB-induced pain. In order to investigate other potential pain mediators in this model we used RNA-seq to perform genome-wide transcriptional profiling in both human and rat skin at the peak of hyperalgesia. In addition we have also measured transcriptional changes in the L4 and L5 DRG of the rat model. Our data show that UVB irradiation produces a large number of transcriptional changes in the skin: 2186 and 3888 genes are significantly dysregulated in human and rat skin, respectively. The most highly up-regulated genes in human skin feature those encoding cytokines (IL6 and IL24), chemokines (CCL3, CCL20, CXCL1, CXCL2, CXCL3 and CXCL5), the prostanoid synthesising enzyme COX-2 and members of the keratin gene family. Overall there was a strong positive and significant correlation in gene expression between the human and rat (R = 0.8022). In contrast to the skin, only 39 genes were significantly dysregulated in the rat L4 and L5 DRGs, the majority of which had small fold change values. Amongst the most up-regulated genes in DRG were REG3B, CCL2 and VGF. Overall, our data shows that numerous genes were up-regulated in UVB irradiated skin at the peak of hyperalgesia in both human and rats. Many of the top up-regulated genes were cytokines and chemokines, highlighting again their potential as pain mediators. However many other genes were also up-regulated and might play a role in UVB-induced hyperalgesia. In addition, the strong gene expression correlation between species re-emphasises the value of the UVB model as translational tool to study inflammatory pain.

Characterisation and mechanisms of bradykinin-evoked pain in man using iontophoresis.

Bradykinin (BK) is an inflammatory mediator that can evoke oedema and vasodilatation, and is a potent algogen signalling via the B1 and B2 G-protein coupled receptors. In naïve skin, BK is effective via constitutively expressed B2 receptors (B2R), while B1 receptors (B1R) are purported to be upregulated by inflammation. The aim of this investigation was to optimise BK delivery to investigate the algesic effects of BK and how these are modulated by inflammation. BK iontophoresis evoked dose- and temperature-dependent pain and neurogenic erythema, as well as thermal and mechanical hyperalgesia (P < 0.001 vs saline control). To differentiate the direct effects of BK from indirect effects mediated by histamine released from mast cells (MCs), skin was pretreated with compound 4880 to degranulate the MCs prior to BK challenge. The early phase of BK-evoked pain was reduced in degranulated skin (P < 0.001), while thermal and mechanical sensitisation, wheal, and flare were still evident. In contrast to BK, the B1R selective agonist des-Arg9-BK failed to induce pain or sensitise naïve skin. However, following skin inflammation induced by ultraviolet B irradiation, this compound produced a robust pain response. We have optimised a versatile experimental model by which BK and its analogues can be administered to human skin. We have found that there is an early phase of BK-induced pain which partly depends on the release of inflammatory mediators by MCs; however, subsequent hyperalgesia is not dependent on MC degranulation. In naïve skin, B2R signaling predominates, however, cutaneous inflammation results in enhanced B1R responses.

Imaging the neural correlates of neuropathic pain and pleasurable relief associated with inherited erythromelalgia in a single subject with quantitative arterial spin labelling.

We identified a patient with severe inherited erythromelalgia secondary to an L858F mutation in the voltage-gated sodium channel Na(v)1.7. The patient reported severe ongoing foot pain, which was exquisitely sensitive to limb cooling. We confirmed this heat hypersensitivity using quantitative sensory testing. Additionally, we employed a novel perfusion imaging technique in a simple block design to assess her baseline erythromelalgia pain vs cooling relief. Robust activations of key pain, pain-affect, and reward-related centres were observed. This combined approach allowed us to confirm the presence of a temperature-sensitive channelopathy of peripheral neurons and to investigate the neural correlates of tonic neuropathic pain and relief in a single subject.

CXCL5 mediates UVB irradiation-induced pain.

Many persistent pain states (pain lasting for hours, days, or longer) are poorly treated because of the limitations of existing therapies. Analgesics such as nonsteroidal anti-inflammatory drugs and opioids often provide incomplete pain relief and prolonged use results in the development of severe side effects. Identification of the key mediators of various types of pain could improve such therapies. Here, we tested the hypothesis that hitherto unrecognized cytokines and chemokines might act as mediators in inflammatory pain. We used ultraviolet B (UVB) irradiation to induce persistent, abnormal sensitivity to pain in humans and rats. The expression of more than 90 different inflammatory mediators was measured in treated skin at the peak of UVB-induced hypersensitivity with custom-made polymerase chain reaction arrays. There was a significant positive correlation in the overall expression profiles between the two species. The expression of several genes [interleukin-1ß (IL-1ß), IL-6, and cyclooxygenase-2 (COX-2)], previously shown to contribute to pain hypersensitivity, was significantly increased after UVB exposure, and there was dysregulation of several chemokines (CCL2, CCL3, CCL4, CCL7, CCL11, CXCL1, CXCL2, CXCL4, CXCL7, and CXCL8). Among the genes measured, CXCL5 was induced to the greatest extent by UVB treatment in human skin; when injected into the skin of rats, CXCL5 recapitulated the mechanical hypersensitivity caused by UVB irradiation. This hypersensitivity was associated with the infiltration of neutrophils and macrophages into the dermis, and neutralizing the effects of CXCL5 attenuated the abnormal pain-like behavior. Our findings demonstrate that the chemokine CXCL5 is a peripheral mediator of UVB-induced inflammatory pain, likely in humans as well as rats.

A gain-of-function mutation in TRPA1 causes familial episodic pain syndrome.

Human monogenic pain syndromes have provided important insights into the molecular mechanisms that underlie normal and pathological pain states. We describe an autosomal-dominant familial episodic pain syndrome characterized by episodes of debilitating upper body pain, triggered by fasting and physical stress. Linkage and haplotype analysis mapped this phenotype to a 25 cM region on chromosome 8q12-8q13. Candidate gene sequencing identified a point mutation (N855S) in the S4 transmembrane segment of TRPA1, a key sensor for environmental irritants. The mutant channel showed a normal pharmacological profile but altered biophysical properties, with a 5-fold increase in inward current on activation at normal resting potentials. Quantitative sensory testing demonstrated normal baseline sensory thresholds but an enhanced secondary hyperalgesia to punctate stimuli on treatment with mustard oil. TRPA1 antagonists inhibit the mutant channel, promising a useful therapy for this disorder. Our findings provide evidence that variation in the TRPA1 gene can alter pain perception in humans.