Technical considerations for isolated limb perfusion: A consensus paper.

BACKGROUND: Isolated limb perfusion (ILP) is a well-established surgical procedure for the administration of high dose chemotherapy to a limb for the treatment of advanced extremity malignancy. Although the technique of ILP was first described over 60 years ago, ILP is utilised in relatively few specialist centres, co-located with tertiary or quaternary cancer centres. The combination of high dose cytotoxic chemotherapy and the cytokine tumour necrosis factor alpha (TNFα), mandates leakage monitoring to prevent potentially serious systemic toxicity. Since the procedure is performed at relatively few specialist centres, an ILP working group was formed with the aim of producing technical consensus guidelines for the procedure to streamline practice and to provide guidance for new centres commencing the technique. METHODS: Between October 2021 and October 2023 a series of face to face online and hybrid meetings were held in which a modified Delphi process was used to develop a unified consensus document. After each meeting the document was modified and recirculated and then rediscussed at subsequent meeting until a greater than 90% consensus was achieved in all recommendations. RESULTS: The completed consensus document comprised 23 topics in which greater than 90% consensus was achieved, with 83% of recommendations having 100% consensus across all members of the working group. The consensus recommendations covered all areas of the surgical procedure including pre-operative assessment, drug dosing and administration, perfusion parameters, hyperthermia, leakage monitoring and theatre logistics, practical surgical strategies and also post-operative care, response evaluation and staff training. CONCLUSION: We present the first joint expert-based consensus statement with respect to the technical aspects of ILP that can serve as a reference point for both existing and new centres in providing ILP.

Clinical and genetic determinants of vitamin D receptor expression in cutaneous melanoma patients.

Decrease of vitamin D receptor (VDR) expression is observed in melanocytic naevi and melanoma compared to normal skin. Little is known about factors influencing VDR expression in cutaneous melanoma (CM). We investigated the correlation of VDR expression in CM with 25-hydroxy vitamin D (25OHD) levels, demographic/clinical parameters, genetic variants of VDR and pathology of the primary tumor. Demographic/clinical parameters were recorded in 407 prospectively recruited CM patients of a multi-center controlled study (ViDMe trial). We determined VDR expression both in the nucleus and in the cytoplasm by semi-quantitative assessment in CM tissue using histochemistry in 279 patients, expressed in percentages and histoscore (H-score). Genomic DNA from 332 patients was extracted to genotype thirteen VDR single nucleotide polymorphisms (SNPs) using TaqMan. VDR expression in CM tissue from 279 patients was correlated with clinical/demographic parameters and 25OHD levels (univariable and multivariable analysis), VDR SNPs (univariable analysis) and pathology parameters of primary CM tissue (univariable analysis). Cytoplasmic VDR expression was increased in patients who stated to have a high sun exposure during their life compared to patients with low sun exposure (p H-score,univariable : 0.001, p H-score,multivariable : 0.004). The A allele of the genetic VDR polymorphism Fok1 was associated with a higher expression of the VDR in the cytoplasm (p cytoplasmic, univariable : 0.001 and p H-score, univariable : 0.02). In the primary tumor, presence of mitosis (p nucleus,%, univariable : 0.002) and perineural invasion (p nucleus,%,univariable : 0.03) were significantly associated with low nuclear VDR expression. ClinicalTrials.gov Identifier: NCT01748448.

A TCF4-dependent gene regulatory network confers resistance to immunotherapy in melanoma.

To better understand intrinsic resistance to immune checkpoint blockade (ICB), we established a comprehensive view of the cellular architecture of the treatment-naive melanoma ecosystem and studied its evolution under ICB. Using single-cell, spatial multi-omics, we showed that the tumor microenvironment promotes the emergence of a complex melanoma transcriptomic landscape. Melanoma cells harboring a mesenchymal-like (MES) state, a population known to confer resistance to targeted therapy, were significantly enriched in early on-treatment biopsies from non-responders to ICB. TCF4 serves as the hub of this landscape by being a master regulator of the MES signature and a suppressor of the melanocytic and antigen presentation transcriptional programs. Targeting TCF4 genetically or pharmacologically, using a bromodomain inhibitor, increased immunogenicity and sensitivity of MES cells to ICB and targeted therapy. We thereby uncovered a TCF4-dependent regulatory network that orchestrates multiple transcriptional programs and contributes to resistance to both targeted therapy and ICB in melanoma.

Variation in response rates to isolated limb perfusion in different soft-tissue tumour subtypes: an international multi-centre study.

OBJECTIVE: The aim of this study was to investigate the response rates of different extremity soft-tissue sarcoma subtypes (eSTS) after isolated limb perfusion (ILP), based on an international multi-centre study. MATERIALS AND METHODS: The retrospective cohort comprised eSTS patients from 17 specialised ILP centres that underwent melphalan-based ILP, with or without recombinant human tumour necrosis factor (rhTNFα) (TM-ILP and M-ILP, respectively). Response was measured on imaging (magnetic resonance imaging) and/or clinical response, for which M-ILPs were excluded. RESULTS: A total of 1109 eSTS patients were included. The three most common histological subtypes were undifferentiated pleomorphic sarcoma (17%, n = 184), synovial sarcoma (16%, n = 175) and myxofibrosarcoma (8%, n = 87). rhTNFα was used in 93% (TM-ILP) and resulted in a significantly better overall response rate (ORR, p = 0.031) and complete responses (CR, p < 0.001) in comparison to M-ILP, without significant differences among histological subgroups. The ORR of TM-ILP was 68%, including 17% CR. Also, 80% showed progressive disease. Significantly higher response rates were shown for Kaposi sarcoma (KS) with 42% CR and 96% ORR (both p < 0.001), and significantly higher CR rates for angiosarcoma (AS, 45%, p < 0.001) and clear cell sarcoma (CCS, 31%, p = 0.049). ILP was followed by resection ≤ 6 months in 80% of the patients. The overall limb salvage rate was 88%, without significant differences among histological subgroups, but was significantly higher for ILP responders compared to non-responders (93% versus 76%, p < 0.001). CONCLUSION: ILP resulted in high response and LRS among all eSTS subtypes, however, with significant differences between subtypes with most promising results for KS, AS and CCS.

Pharmacological induction of membrane lipid poly-unsaturation sensitizes melanoma to ROS inducers and overcomes acquired resistance to targeted therapy.

BACKGROUND: One of the key limitations of targeted cancer therapies is the rapid onset of therapy resistance. Taking BRAF-mutant melanoma as paradigm, we previously identified the lipogenic regulator SREBP-1 as a central mediator of resistance to MAPK-targeted therapy. Reasoning that lipogenesis-mediated alterations in membrane lipid poly-unsaturation lie at the basis of therapy resistance, we targeted fatty acid synthase (FASN) as key player in this pathway to evoke an exquisite vulnerability to clinical inducers of reactive oxygen species (ROS), thereby rationalizing a novel clinically actionable combination therapy to overcome therapy resistance. METHODS: Using gene expression analysis and mass spectrometry-based lipidomics of BRAF-mutant melanoma cell lines, melanoma PDX and clinical data sets, we explored the association of FASN expression with membrane lipid poly-unsaturation and therapy-resistance. Next, we treated therapy-resistant models with a preclinical FASN inhibitor TVB-3664 and a panel of ROS inducers and performed ROS analysis, lipid peroxidation tests and real-time cell proliferation assays. Finally, we explored the combination of MAPK inhibitors, TVB-3664 and arsenic trioxide (ATO, as a clinically used ROS-inducer) in Mel006 BRAF mutant PDX as a gold model of therapy resistance and assessed the effect on tumor growth, survival and systemic toxicity. RESULTS: We found that FASN expression is consistently increased upon the onset of therapy resistance in clinical melanoma samples, in cell lines and in Mel006 PDX and is associated with decreased lipid poly-unsaturation. Forcing lipid poly-unsaturation in therapy-resistant models by combining MAPK inhibition with FASN inhibition attenuated cell proliferation and rendered cells exquisitely sensitive to a host of ROS inducers. In particular, the triple combination of MAPK inhibition, FASN inhibition, and the clinical ROS-inducing compound ATO dramatically increased survival of Mel006 PDX models from 15 to 72% with no associated signs of toxicity. CONCLUSIONS: We conclude that under MAPK inhibition the direct pharmacological inhibition of FASN evokes an exquisite vulnerability to inducers of ROS by increasing membrane lipid poly-unsaturation. The exploitation of this vulnerability by combining MAPK and/or FASN inhibitors with inducers of ROS greatly delays the onset of therapy resistance and increases survival. Our work identifies a clinically actionable combinatorial treatment for therapy-resistant cancer.

Surgical management after Oxaliplatin extravasation: A case report and literature review.

This case report describes a unique case of chronic reaction after extravasation of oxaliplatin. The pain and extensive subcutaneous induration did not resolve after 9 months of conservative treatment. Surgical debridement with removal of the totally implantable venous access device (TIVAD) resulted in immediate resolution of the symptoms. Oxaliplatin has both irritant and vesicant properties that are difficult to distinguish at initial clinical presentation. In most literature cases complaints resolve within 3 months with conservative treatment yet surgical debridement should be considered if complaints persist beyond this period.

Melanoma cell plasticity poses diagnostic challenges: a case series.

Phenotype switching is an emerging concept in melanoma research and deals with the cancer cell plasticity. In this paper, we present five cases of patients with metastatic malignant melanoma where the tumor underwent dramatic morphological and immunohistochemical changes thereby mimicking other types of malignancies. The diagnosis of melanoma in all these cases was based on the mutational profile of the tumor assessed by next-generation sequencing compared to the primary lesion or local regional lymph nodes. These cases highlight the importance of thorough diagnostic measures in patients with metastatic melanoma who show progressive disease and where basic pathological assessment shows a diagnostic discrepancy.

Mapping the Immune Landscape in Metastatic Melanoma Reveals Localized Cell-Cell Interactions That Predict Immunotherapy Response.

While immune checkpoint-based immunotherapy (ICI) shows promising clinical results in patients with cancer, only a subset of patients responds favorably. Response to ICI is dictated by complex networks of cellular interactions between malignant and nonmalignant cells. Although insights into the mechanisms that modulate the pivotal antitumoral activity of cytotoxic T cells (Tcy) have recently been gained, much of what has been learned is based on single-cell analyses of dissociated tumor samples, resulting in a lack of critical information about the spatial distribution of relevant cell types. Here, we used multiplexed IHC to spatially characterize the immune landscape of metastatic melanoma from responders and nonresponders to ICI. Such high-dimensional pathology maps showed that Tcy gradually evolve toward an exhausted phenotype as they approach and infiltrate the tumor. Moreover, a key cellular interaction network functionally linked Tcy and PD-L1+ macrophages. Mapping the respective spatial distributions of these two cell populations predicted response to anti-PD-1 immunotherapy with high confidence. These results suggest that baseline measurements of the spatial context should be integrated in the design of predictive biomarkers to identify patients likely to benefit from ICI. SIGNIFICANCE: This study shows that spatial characterization can address the challenge of finding efficient biomarkers, revealing that localization of macrophages and T cells in melanoma predicts patient response to ICI. See related commentary by Smalley and Smalley, p. 3198.

Clinical trial: a controlled trial of baclofen add-on therapy in PPI-refractory gastro-oesophageal reflux symptoms.

BACKGROUND: Proton pump inhibitors (PPI) have no effect on non-acid reflux events which can continue to provoke gastro-oesophageal reflux disease (GERD) symptoms. Baclofen, a γ-aminobutyric acid agonist, can decrease non-acid reflux but its symptomatic benefit in refractory GERD symptoms is understudied. AIMS: To assess the efficacy of baclofen 10 mg t.i.d. vs placebo as add-on therapy in PPI-refractory GERD symptoms, in a randomised, double-blind, placebo-controlled study. METHODS: Patients with persisting typical GERD symptoms on b.i.d. PPI therapy were randomised to 4 weeks of baclofen 10 mg or placebo t.i.d. Before and after treatment, patients underwent 24 h impedance-pH monitoring on-PPI. Throughout the study, patients filled out ReQuest diaries. Data were analysed using mixed models. RESULTS: About 60 patients were included (age 47.5 years [range 19-73], 41f/19 m), 31 patients were randomised to baclofen. One patient withdrew consent and five in the baclofen group stopped treatment due to side effects. There was a trend towards a better response for general wellbeing in the baclofen-treated group compared to placebo (p = 0.06). When subdividing patients according to symptom association probability (SAP), only the SAP+ (n = 25) group improved significantly with baclofen (pcorr  = 0.02), and worsened with placebo (pcorr  = 0.008). The total number of reflux events decreased over time (p = 0.01), mainly due to the baclofen condition (pcorr  = 0.1). The number of reflux events with a high proximal extent dropped significantly after baclofen (pcorr  = 0.009), but not placebo. CONCLUSION: Baclofen decreases several reflux parameters in PPI refractory GERD symptoms, but pH-impedance monitoring is necessary before treatment as only SAP+ patients experience clinical benefit after 4 weeks.

Determinants of 25-hydroxyvitamin D Status in a Cutaneous Melanoma Population.

Vitamin D status is influenced by well-known determinants, but factors associated with low 25-hydroxyvitamin D levels in the cutaneous melanoma population are not well defined. The aim of this study was to confirm the well-known determinants and to assess new determinants for 25-hydroxyvitamin D levels in a cutaneous melanoma population. In a prospectively included cohort of 387 patients with cutaneous melanoma the association of 25-hydroxyvitamin D levels with sex, age, body mass index, time of blood withdrawal, Fitzpatrick phototype, vitamin D supplementation, score for intensity of lifetime sun exposure, smoking, education level, hair and skin colour, eye colour, total number of benign naevi, freckles and parameters of chronic sun damage was investigated. In addition, 25-hydroxyvitamin D levels were correlated with pathological parameters of the primary tumour and melanoma stage (8th edition of the American Joint Committee on Cancer (AJCC). Univariate and multivariate logistic regressions were performed using R software. The following factors had a significant effect on vitamin D status: body mass index, seasonal time of blood sampling, vitamin D supplementation, and a subtype of skin, and hair colour.

Diagnostic error in detection of fractured and migrated totally implantable venous access device fragments and experience with percutaneous retrieval: A report of 27 cases.

PURPOSE: To assess diagnostic efficacy/error to identify broken or dislocated totally implantable venous access device (TIVAD) fragments on radiological studies and to analyze interventional outcome of percutaneous retrieval. MATERIALS AND METHODS: Retrospective, single-center analysis of 27 patients, referred for percutaneous retrieval of embolized TIVAD fragments between 2000 and 2018. Demographic data, underlying disease, diagnostic studies, diagnostic error, interval between implantation and diagnosis of TIVAD-dysfunction, interval between diagnosis and retrieval, anatomical location of the embolized fragments, and technical aspects of retrieval procedure were identified from the patients' electronic medical records. RESULTS: Overall, diagnostic error was found in six patients (22%) with an average delay of 53 days. Ten fractures were caused during surgical removal, eleven fractures by pinching between first rib and clavicle and six cases by spontaneous disconnection between reservoir and catheter. Success rate of retrieval was 96% and the complication rate 0%. CONCLUSION: Fractured or retained TIVAD fragments were initially overlooked on radiological studies in more than 20% of patients. Percutaneous retrieval of broken and dislocated TIVAD fragments is very safe and highly successful.

Road to Metastasis: The TWEAK Pathway as a Discriminant between Metastasizing and Non-Metastasizing Thick Melanomas.

Cutaneous melanoma (CM) is the most aggressive form of skin cancer, and its worldwide incidence is rapidly increasing. Early stages can be successfully treated by surgery, but once metastasis has occurred, the prognosis is poor. However, some 5-10% of thick (≥2 mm) melanomas do not follow this scenario and run an unpredictable course. Little is known about the factors that contribute to metastasis in some patient with thick melanomas and the lack thereof in thick melanoma patients who never develop metastatic disease. We were therefore interested to study differential gene expression and pathway analysis and compare non-metastatic and metastatic thick melanomas. We found that the TNF-like weak inducer of apoptosis (TWEAK) pathway was upregulated in thick non-metastasizing melanomas. MAP3K14 (NIK1), BIRC2 (cIAP1), RIPK1, CASP7, CASP8, and TNF play an important role in inhibiting proliferation and invasion of tumor cells via the activation of the non-canonical NF-κB signaling pathway. In particular, this pathway sensitizes melanoma cells to TNF-alpha and activates the apoptosis module of the TWEAK pathway in thick non-metastasizing melanomas. Hence, our study suggests a potential role of the TWEAK pathway in inhibiting thick melanoma from metastasis. Exploitation of these genes and the pathway they control may open future therapeutic avenues.

Corrigendum to "Clinical Presentation, Natural History, and Therapeutic Approach in Patients with Solitary Fibrous Tumor: A Retrospective Analysis".

[This corrects the article DOI: 10.1155/2020/1385978.].

The role of serotonin in the control of esophageal sensitivity assessed by multimodal stimulation in health.

BACKGROUND: Esophageal hypersensitivity is considered an important pathophysiological mechanism in refractory gastroesophageal reflux disease (GERD) patients. Serotonin (5-HT) plays an important role in the regulation of GI (gastrointestinal) secretion, motility and sensitivity. Previous studies found that altered 5-HT availability has no clear effects on esophageal/GI sensations. Our aim was therefore to investigate the role of 5-HT in esophageal sensitivity in healthy volunteers (HV). METHODS: Esophageal sensitivity to thermal, mechanical, electrical, and chemical stimuli was assessed in 3 different placebo-controlled studies. In the first study, the effect of citalopram (40 mg; 5-HT reuptake inhibitor; intravenous) was investigated (n = 14). In the second study, the effect of buspirone (20 mg; 5HT1A agonist; oral) was investigated (n = 10). In the third study, acute tryptophan depletion (ATD) was used to decrease 5-HT levels to investigate the effect of reduced 5-HT availability on esophageal sensitivity (n = 15). KEY RESULTS: No difference was observed in esophageal sensitivity after the administration of citalopram or buspirone (all p > 0.06). In contrast, pain perception threshold to chemical stimulation was increased after ATD (p = 0.017, Cohen's d+ = 0.67). No effect was found on the first perception or pain tolerance threshold. ATD had no influence on esophageal sensitivity to thermal, mechanical, and electrical stimulation compared with placebo. CONCLUSIONS AND INFERENCES: ATD, which induces 5-HT depletion, significantly decreased pain perception threshold during chemical stimulation, without affecting sensitivity to mechanical, thermal, or electrical stimulation. These findings confirm the involvement of 5-HT in the control of esophageal acid sensitivity, but identifying the receptors involved requires more ligands and studies.

Functional heterogeneity of lymphocytic patterns in primary melanoma dissected through single-cell multiplexing.

In melanoma, the lymphocytic infiltrate is a prognostic parameter classified morphologically into 'brisk', 'non-brisk' and 'absent' entailing a functional association that has never been proved. Recently, it has been shown that lymphocytic populations can be very heterogeneous, and that anti-PD-1 immunotherapy supports activated T cells. Here, we characterize the immune landscape in primary melanoma by high-dimensional single-cell multiplex analysis in tissue sections (MILAN technique) followed by image analysis, RT-PCR and shotgun proteomics. We observed that the brisk and non-brisk patterns are heterogeneous functional categories that can be further sub-classified into active, transitional or exhausted. The classification of primary melanomas based on the functional paradigm also shows correlation with spontaneous regression, and an improved prognostic value when compared to that of the brisk classification. Finally, the main inflammatory cell subpopulations that are present in the microenvironment associated with activation and exhaustion and their spatial relationships are described using neighbourhood analysis.

How to select patients for antireflux surgery? The ICARUS guidelines (international consensus regarding preoperative examinations and clinical characteristics assessment to select adult patients for antireflux surgery).

OBJECTIVE: Antireflux surgery can be proposed in patients with GORD, especially when proton pump inhibitor (PPI) use leads to incomplete symptom improvement. However, to date, international consensus guidelines on the clinical criteria and additional technical examinations used in patient selection for antireflux surgery are lacking. We aimed at generating key recommendations in the selection of patients for antireflux surgery. DESIGN: We included 35 international experts (gastroenterologists, surgeons and physiologists) in a Delphi process and developed 37 statements that were revised by the Consensus Group, to start the Delphi process. Three voting rounds followed where each statement was presented with the evidence summary. The panel indicated the degree of agreement for the statement. When 80% of the Consensus Group agreed (A+/A) with a statement, this was defined as consensus. All votes were mutually anonymous. RESULTS: Patients with heartburn with a satisfactory response to PPIs, patients with a hiatal hernia (HH), patients with oesophagitis Los Angeles (LA) grade B or higher and patients with Barrett's oesophagus are good candidates for antireflux surgery. An endoscopy prior to antireflux surgery is mandatory and a barium swallow should be performed in patients with suspicion of a HH or short oesophagus. Oesophageal manometry is mandatory to rule out major motility disorders. Finally, oesophageal pH (±impedance) monitoring of PPI is mandatory to select patients for antireflux surgery, if endoscopy is negative for unequivocal reflux oesophagitis. CONCLUSION: With the ICARUS guidelines, we generated key recommendations for selection of patients for antireflux surgery.

Solar Lentigines are Associated with Better Outcome in Cutaneous Melanoma.

The rising incidence of cutaneous melanoma and its stable high mortality rates despite innovative cancer care, require better prediction of the clinical outcome. In a large cutaneous melanoma population we explored whether the known clinical risk factors for melanoma susceptibility (nevus phenotype, phototype, family and personal history of melanoma and sun damage) affect melanoma outcomes. A total of 1,530 melanoma patients were included. Multivariable analysis adjusted for age, gender, melanoma stage, localization and subtype showed that familial melanoma, solar lentigines on head and neck, the back of hands, arms and shoulders were associated with a better relapse free survival. The presence of atypical naevi was associated with an increased risk of relapse. After Bonferroni correction, the correlation between presence of solar lentigines on the back of the hands and arms remained the most robust and significant prognostic factor for the relapse free survival in cutaneous melanoma patients.

Melanoma susceptibility variant rs869330 in the MTAP gene is associated with melanoma outcome.

The rising incidence of cutaneous melanoma (CM), an aggressive skin cancer, emphasizes the need for novel biomarkers to guide personalized care and better predict outcome. Genetic factors including germline risk variants are promising candidates for this aim. We explored the association between germline risk variants and melanoma outcome in a large genetically homogenous Belgian melanoma population, focusing on single nucleotide polymorphisms which generated the highest association with melanoma susceptibility. Between 2004 and 2014, blood samples of 1088 patients with histologically confirmed CM were collected and genotyped for nine variants. Cox proportional hazard models were used to assess the association between each single nucleotide polymorphism and relapse-free survival and overall survival, adjusted by age, sex, melanoma stage, site, and subtype. We identified significant associations for rs869330 (in the methylthioadenosine phosphorylase - MTAP gene) with overall survival (hazard ratio = 0.760, P = 0.048, 95% confidence interval: 0.580-0.998) and relapse-free survival (hazard ratio = 0.800, P = 0.020, 95% confidence interval: 0.650-0.970). This exploratory study is the first to show a significant association between the rs869330 variant (in the MTAP gene) and outcome in a large CM population.

The optimal order of stimulation modalities and reproducibility of the multimodal esophageal stimulation paradigm.

BACKGROUND: Esophageal hypersensitivity can be triggered by different stimuli. We use a multimodal stimulation model to study esophageal sensitivity to four sensory modalities: thermal, mechanical, electrical, and chemical stimulation. The optimal order of these stimulations needs further validation. METHODS: Esophageal sensitivity to thermal (heated saline solution), mechanical (balloon distention), electrical (block pulses with electrodes), and chemical stimulation (acid solution, 0.1 N HCl) was assessed in 10 subjects. In one session, thermal stimulation was performed first, followed by mechanical stimulation ("original protocol"). In a second session, mechanical stimulation was performed first, followed by temperature stimulation ("reversed protocol"). Besides, the impact of balloon distention speed (25 mL/min vs 50 mL/min) during mechanical stimulation was evaluated. Secondly, in order to establish reproducibility, independent control sessions of multimodal stimulations in 15 healthy volunteers were used retrospectively. KEY RESULTS: A significant difference in pain perception threshold for thermal stimulation was found between the original and reversed protocol (P = 0.046), indicating that mechanical stimulation can sensitize the esophagus to thermal stimulation. Balloon distention rate had no impact on sensitivity thresholds for mechanical stimulation. Concerning the reproducibility, there were no differences for thermal, mechanical, electrical, and chemical stimulation in any of the control sessions. CONCLUSIONS: The optimal order of the multimodal stimulation protocol was to start with the thermal stimulation, followed by mechanical, electrical, and chemical stimulation. The optimal balloon distention rate was 25 mL/min. Multimodal esophageal stimulation generates reproducible perception scores in health and therefore provides a reliable method to assess esophageal sensitivity changes after interventions that may alter esophageal sensitivity.

Response to targeted therapy in two patients with metastatic melanoma carrying rare BRAF exon 15 mutations: A598_T599insV and V600_K601delinsE.

Concurrent BRAF-MEK inhibition improves clinical outcomes in patients with advanced BRAF V600E/K-mutant melanoma. There is currently less evidence for the efficacy of this treatment in patients with rare BRAF non-V600E/K genotypes. We report on two patients with rare BRAF exon 15 mutations - BRAF A598_T599insV and V600_K601delinsE - obtaining clinical benefit and a radiological response to inhibitors directed against the mitogen-activated protein kinase pathway. This highlights the importance of using tests that detect both V600E/K and non-V600E/K BRAF mutations to keep open the possibility of treatment with targeted therapy in patients with uncommon, yet potentially actionable, BRAF exon 15 mutations.