Monoclonal antibody against macrophage colony-stimulating factor suppresses circulating monocytes and tissue macrophage function but does not alter cell infiltration/activation in cutaneous lesions or clinical outcomes in patients with cutaneous lupus erythematosus

Topical Mupirocin Treatment Reduces Interferon and Myeloid Signatures in Cutaneous Lupus Erythematous Lesions Through Targeting of Staphyloccal Species

OBJECTIVE

Cutaneous lupus erythematosus (CLE) is an inflammatory skin manifestation of systemic lupus erythematosus. Type I interferons (IFNs) promote inflammatory responses and are elevated in CLE lesions. We recently reported that CLE lesions are frequently colonized with Staphylococcus aureus. Here, we follow up via a proof-of-concept study to investigate whether type I IFN and inflammatory gene signatures in CLE lesions can be modulated with mupirocin, a topical antibiotic treatment against S aureus-mediated skin infections.

METHODS

Participants with active CLE lesions (n = 12) were recruited and randomized into a week of topical treatment with either 2% mupirocin or petroleum jelly vehicle. Paired samples were collected before and after seven days of treatment to assess microbial lesional skin responses. Microbial samples from nares and lesional skin were used to determine baseline and posttreatment Staphylococcus abundance and microbial community profiles by 16S ribosomal RNA gene sequencing. Inflammatory responses were evaluated by bulk RNA sequencing of lesional skin biopsies.

RESULTS

We identified 173 differentially expressed genes in CLE lesions after topical mupirocin treatment. Decreased lesional Staphylococcus burden correlated with decreased IFN pathway signaling and inflammatory gene expression and barrier dysfunction. Interestingly, mupirocin treatment lowered skin monocyte levels, and this mupirocin-associated depletion of monocytes correlated with decreased inflammatory gene expression.

CONCLUSION

Mupirocin treatment decreased lesional Staphylococcus, and this correlated with decreased IFN signaling and inflammatory gene expression. This study suggests a topical antibiotic could be employed to decrease lupus skin inflammation and type I IFN responses by reducing Staphylococcus colonization.

Severity Scores for Cutaneous Lupus Erythematosus

Despite the significant disease burden of cutaneous lupus erythematosus (CLE), there have been no United States Food and Drug Administration-approved therapies for 65 years. To facilitate advancement of therapies, severity scores are needed to evaluate QOL, how patients feel, activity of disease, and organ-specific damage to assess response to therapies and disease progression. In this paper, we delineate the development process of provider- and patient-reported severity scores for CLE. Cutaneous Lupus Disease Area and Severity Index (CLASI), a provider-reported measure that distinguishes between activity and damage, has undergone rigorous validation and reliability testing for over 20 years. Its performance has been tested in clinical trials as a primary or secondary endpoint and tool to stratify patients. As an objective disease measure that captures a provider's perspective of disease activity and damage, the CLASI inherently does not assess disease impact on patients' QOL. Cutaneous Lupus Erythematosus Quality of Life (CLEQoL), a patient-reported measure, captures features elucidated through focus groups, including symptoms, emotions, functioning, body image, and photosensitivity. It has undergone psychometric property testing to ensure reliability and validity. Together, CLASI and CLEQoL are simple and reliable CLE-specific severity scores capturing disease activity, damage, and QOL from provider and patient perspectives.

Phase 1 and preclinical profiling of ESM-HDAC391, a myeloid-targeted histone deacetylase inhibitor, shows enhanced pharmacology and monocytopaenia

AIMS

To improve the tolerability and therapeutic application of histone deacetylase inhibitors (HDACi), by application of an esterase-sensitive motif (ESM), to target pharmacological activity directly to mononuclear myeloid cells expressing the processing enzyme carboxylesterase-1 (CES1).

METHODS

This first-in-human study comprised single and multiple ascending dose cohorts to determine safety and tolerability. Pharmacodynamic parameters included acetylation, cytokine inhibition and intracellular concentrations of processed acid metabolite in isolated monocytes. Mechanistic work was conducted in vitro and in a CES1/Es1e^lo mouse strain.

RESULTS

ESM-HDAC391 showed transient systemic exposure (plasma half-life of 21-30 min) but selective retention of processed acid for at least 12 hours, resulting in robust targeted mechanistic engagement (increased acetylation in monocytes plus inhibition of ex vivo stimulated cytokine production). ESM-HDAC391 was well tolerated and clinical toxicities common to non-targeted HDACi were not observed. ESM-HDAC391 treatment was accompanied by the novel finding of a dose-dependent monocyte depletion that was transient and reversible and which plateaued at 0.06 × 10⁹ monocytes/L after repeat dosing with 20 or 40 mg. Characterisation of monocyte depletion in transgenic mice (CES1/Es1e^lo ) suggested that colony stimulating factor 1 receptor loss on circulating cells contributed to ESM-HDAC-mediated depletion. Further mechanistic investigations using human monocytes in vitro demonstrated HDACi-mediated change in myeloid fate through modulation of colony stimulating factor 1 receptor and downstream effects on cell differentiation.

CONCLUSION

These findings demonstrate selective targeting of monocytes in humans using the ESM approach and identify monocytopaenia as a novel outcome of ESM-HDACi treatment, with implications for potential benefit of these molecules in myeloid-driven diseases.

Recent advances in cutaneous lupus

Cutaneous lupus erythematosus (CLE) is an inflammatory and autoimmune skin condition that affects patients with systemic lupus erythematosus (SLE) and exists as an isolated entity without associated SLE. Flares of CLE, often triggered by exposure to ultraviolet (UV) light result in lost productivity and poor quality of life for patients and can be associated with trigger of systemic inflammation. In the past 10 years, the knowledge of CLE etiopathogenesis has grown, leading to promising targets for better therapies. Development of lesions likely begins in a pro-inflammatory epidermis, conditioned by excess type I interferon (IFN) production to undergo increased cell death and inflammatory cytokine production after UV light exposure. The reasons for this inflammatory predisposition are not well-understood, but may be an early event, as ANA + patients without criteria for autoimmune disease exhibit similar (although less robust) findings. Non-lesional skin of SLE patients also exhibits increased innate immune cell infiltration, conditioned by excess IFNs to release pro-inflammatory cytokines, and potentially increase activation of the adaptive immune system. Plasmacytoid dendritic cells are also found in non-lesional skin and may contribute to type I IFN production, although this finding is now being questioned by new data. Once the inflammatory cycle begins, lesional infiltration by numerous other cell populations ensues, including IFN-educated T cells. The heterogeneity amongst lesional CLE subtypes isn't fully understood, but B cells appear to discriminate discoid lupus erythematosus from other subtypes. Continued discovery will provide novel targets for additional therapeutic pursuits. This review will comprehensively discuss the contributions of tissue-specific and immune cell populations to the initiation and propagation of disease.

Trial of Anti-BDCA2 Antibody Litifilimab for Cutaneous Lupus Erythematosus

BACKGROUND

Blood dendritic cell antigen 2 (BDCA2) is a receptor that is exclusively expressed on plasmacytoid dendritic cells, which are implicated in the pathogenesis of lupus erythematosus. Whether treatment with litifilimab, a humanized monoclonal antibody against BDCA2, would be efficacious in reducing disease activity in patients with cutaneous lupus erythematosus has not been extensively studied.

METHODS

In this phase 2 trial, we randomly assigned adults with histologically confirmed cutaneous lupus erythematosus with or without systemic manifestations in a 1:1:1:1 ratio to receive subcutaneous litifilimab (at a dose of 50, 150, or 450 mg) or placebo at weeks 0, 2, 4, 8, and 12. We used a dose-response model to assess whether there was a response across the four groups on the basis of the primary end point, which was the percent change from baseline to 16 weeks in the Cutaneous Lupus Erythematosus Disease Area and Severity Index-Activity score (CLASI-A; scores range from 0 to 70, with higher scores indicating more widespread or severe skin involvement). Safety was also assessed.

RESULTS

A total of 132 participants were enrolled; 26 were assigned to the 50-mg litifilimab group, 25 to the 150-mg litifilimab group, 48 to the 450-mg litifilimab group, and 33 to the placebo group. Mean CLASI-A scores for the groups at baseline were 15.2, 18.4, 16.5, and 16.5, respectively. The difference from placebo in the change from baseline in CLASI-A score at week 16 was -24.3 percentage points (95% confidence interval [CI] -43.7 to -4.9) in the 50-mg litifilimab group, -33.4 percentage points (95% CI, -52.7 to -14.1) in the 150-mg group, and -28.0 percentage points (95% CI, -44.6 to -11.4) in the 450-mg group. The least squares mean changes were used in the primary analysis of a best-fitting dose-response model across the three drug-dose levels and placebo, which showed a significant effect. Most of the secondary end points did not support the results of the primary analysis. Litifilimab was associated with three cases each of hypersensitivity and oral herpes infection and one case of herpes zoster infection. One case of herpes zoster meningitis occurred 4 months after the participant received the last dose of litifilimab.

CONCLUSIONS

In a phase 2 trial involving participants with cutaneous lupus erythematosus, treatment with litifilimab was superior to placebo with regard to a measure of skin disease activity over a period of 16 weeks. Larger and longer trials are needed to determine the effect and safety of litifilimab for the treatment of cutaneous lupus erythematosus. (Funded by Biogen; LILAC ClinicalTrials.gov number, NCT02847598.).

Emerging Therapeutics in the Management of Connective Tissue Disease. Part I. Lupus Erythematosus and Sjögren's Syndrome

The management of connective tissue diseases is dramatically evolving with the advent of biologics and novel oral systemic therapeutics. Despite involvement in the care of these complex patients, there is a knowledge gap in the field of dermatology regarding these emerging agents. The first article in this continuing medical education series discusses new and emerging therapeutics for lupus erythematosus and Sjögren's syndrome that target cells, intracellular signaling pathways, and cytokines.

Cardiovascular Disease-Associated Skin Conditions

According to data from the American Heart Association and the World Health Organization, cardiovascular disease (CVD) is the most frequent cause of premature death. Several inflammatory and non-inflammatory skin diseases have been associated with metabolic syndrome and cardiovascular risk (CVR). Here, we classified these conditions into traditionally CVR-associated and those that have been linked to a lesser degree. Psoriasis and hidradenitis suppurativa are commonly associated with CVD, sharing common inflammatory pathways and a higher prevalence of traditional cardiovascular risk factors. Many other diseases could be associated indirectly – with no common pathogenic features with the atheromatous disease – but share a higher prevalence of standard cardiovascular risk and chronic inflammatory state. This review aims to highlight the associated cardiovascular risk that exists for some dermatologic diseases and sensitize cardiologists, dermatologists, and first care providers to implement risk factor control promptly.

Clinical evaluation of colony-stimulating factor 1 receptor inhibitors

Signaling through colony-stimulating factor 1 receptor (CSF1R) regulates the development, differentiation, and activation of mononuclear phagocytic cells. Inhibition of this pathway provides an opportunity for therapeutic intervention in diseases in which these cells play a pathogenic role, including cancers, inflammation, fibrosis, and others. Multiple monoclonal antibodies and small molecule inhibitors targeting CSF1R or its known ligands CSF1 and IL-34 have been clinically tested and are generally well tolerated with side effects associated with on-target macrophage inhibition or depletion. To date, clinical activity of CSF1R inhibitors has been primarily observed in diffuse-type tenosynovial giant cell tumors, a disease characterized by genetic alterations in CSF1 leading to dysregulated CSF1R signaling. Expanded development into novel indications such as chronic graft vs host disease may provide new opportunities to further explore areas where a role for CSF1R dependent monocytes and macrophages has been established. This review presents key findings from the clinical development of 12 CSF1/CSF1R targeted therapies as monotherapy or in combination with immune checkpoint inhibitors and chemotherapy.

Use of the Cutaneous Lupus Disease Area and Severity Index as an outcome measure in clinical trials: a descriptive study

This study summarizes the use, since its inception, of the Cutaneous Lupus Disease Area and Severity Index (CLASI) as an outcome measure in clinical studies. We systematically searched the MEDLINE, PubMed, EMBASE and Cochrane databases for papers including the term 'cutaneous lupus disease area and severity index' and its abbreviations up to August 2017, identifying 205 abstracts. Following shortlisting, two independent physicians critically reviewed 71 papers for data extraction. We found that a limited number of high-quality studies used the CLASI scoring as an outcome measure. We concluded that further validation is necessary to identify the effectiveness of the CLASI in the assessment of cutaneous lupus erythematosus subtypes. The use of standardized core patient- and physician-reported outcome measures may reduce heterogeneity and allow comparisons between patients enrolled in clinical trials. This would improve the relevance within clinical practice, where the use of CLASI is currently limited.

Reproducing human and cross-species drug toxicities using a Liver-Chip

Nonclinical rodent and nonrodent toxicity models used to support clinical trials of candidate drugs may produce discordant results or fail to predict complications in humans, contributing to drug failures in the clinic. Here, we applied microengineered Organs-on-Chips technology to design a rat, dog, and human Liver-Chip containing species-specific primary hepatocytes interfaced with liver sinusoidal endothelial cells, with or without Kupffer cells and hepatic stellate cells, cultured under physiological fluid flow. The Liver-Chip detected diverse phenotypes of liver toxicity, including hepatocellular injury, steatosis, cholestasis, and fibrosis, and species-specific toxicities when treated with tool compounds. A multispecies Liver-Chip may provide a useful platform for prediction of liver toxicity and inform human relevance of liver toxicities detected in animal studies to better determine safety and human risk.

Current Insights in Cutaneous Lupus Erythematosus Immunopathogenesis

Cutaneous Lupus Erythematosus (CLE) is a clinically diverse group of autoimmune skin diseases with shared histological features of interface dermatitis and autoantibodies deposited at the dermal-epidermal junction. Various genetic and environmental triggers of CLE promote infiltration of T cells, B cells, neutrophils, antigen presenting cells, and NK cells into lesional skin. In this mini-review, we will discuss the clinical features of CLE, insights into CLE immunopathogenesis, and novel treatment approaches.

Cutaneous Lupus Erythematosus: Current and Future Pathogenesis-Directed Therapies

Cutaneous lupus erythematosus (CLE) is an autoimmune disease of the skin with significant morbidity. Current treatments are often inadequate to control disease and there are no Food and Drug Administration (FDA)-approved therapies for this potentially debilitating disease, underscoring an unmet medical need. Recent insights into disease pathogenesis have implicated innate and adaptive immune components, including type I and type III interferons in the development of CLE. Promising clinical trials based on these insights are now underway. However, the full spectrum of immune cells, cytokines, and environmental triggers contributing to disease remain to be elucidated. In this review, we will highlight the current understanding of CLE immunopathogenesis, the ongoing clinical trial landscape, and provide a framework for designing future therapeutic strategies for CLE based on new insights into disease pathogenesis.

Current Insights Into The Management Of Discoid Lupus Erythematosus

Discoid lupus erythematosus is the most disfiguring and common presentation of chronic cutaneous lupus erythematosus. Although most patients will respond to lifestyle measures and topical treatment, a non-negligible number of patients will require systemic and physical therapy, either alone or in combination. We performed a review of the available evidence on the discoid lupus erythematosus treatment. Lifestyle measures and topical treatment (corticosteroids and topical calcineurin inhibitors) remain the therapeutic strategies with the highest evidence level. Within systemic treatment approaches, antimalarial drugs are still the first-line therapy, while other systemic and physical therapies have highly variable evidence. Hence, we propose a therapeutic algorithm based on the strength of recommendations of the different treatment modalities, focusing on the refractory disease.

Management of cutaneous manifestations of lupus erythematosus: A systematic review

BACKGROUND

Cutaneous lupus erythematosus (CLE), occurring with or without systemic lupus erythematosus (SLE), is a group of inflammatory skin diseases that can be very debilitating, causing significant psychological distress, and sometimes scarring.

OBJECTIVES

We sought to comprehensively present the evidence for different treatment modalities in patients with cutaneous manifestations of lupus erythematosus (LE).

METHODS

Medline, Embase, Scopus and Cochrane CENTRAL were searched electronically from 1990 to March 2019, using keywords related to cutaneous lupus and synonyms and treatment. Articles retrieved were screened for relevance, including reference lists of retrieved reviews. We included clinical trials, observational studies or case series with ≥5 patients focussing on treatment of CLE, with or without SLE.

RESULTS

The search identified 6637 studies, of which 107 were included. Each study commonly included a heterogeneous mixture of CLE subtypes, with or without SLE. The 107 included studies investigated 11 different categories of treatment in 7343 patients. Treatments included topical calcineurin inhibitors (13 studies), sun protection (5 studies), R-salbutamol cream (2 studies), antimalarials (22 studies), synthetic DMARDs (10 studies), retinoids (2 studies), thalidomide/lenalidomide (22 studies), biologic therapies (15 studies), intravenous immune globulin (3 studies), laser (6 studies) and other therapies (7 studies). General measures to be considered include smoking cessation, sun protection measures and optimisation of vitamin D levels. Moderate evidence exists for benefit with topical CNIs, particularly as a steroid sparing agent in areas at high risk of steroid complications (e.g. facial skin). There is moderate evidence for hydroxychloroquine, which is first-line in SLE patients, limited evidence to support other synthetic DMARDs, and moderate evidence supporting thalidomide but with significant risk of toxicity. Of biologic therapies, there are moderate data to support belimumab. Limited evidence exists for other therapies.

CONCLUSION

Many management options are available for CLE, including topical, systemic and biologic therapies, with a variable balance of efficacy and toxicity. There is a paucity of high-quality clinical trial data. Further trials are required to better understand optimal management of CLE, particularly in specific subgroups.

Colony-Stimulating Factor-1 Antibody Lacnotuzumab in a Phase 1 Healthy Volunteer Study and Mechanistic Investigation of Safety Outcomes

The colony-stimulating factor-1 (CSF-1) receptor pathway has been implicated in a variety of diseases, and CSF-1-dependent mechanisms are also involved in bloodborne protein clearance. Lacnotuzumab is a novel, high-affinity, humanized, anti-CSF-1 monoclonal antibody that prevents CSF-1-mediated receptor activation. This phase 1, two-part, double-blind study in healthy volunteers assessed the safety and tolerability of lacnotuzumab and its pharmacokinetics (PK) and pharmacodynamic properties. Part A (n = 36) was a single, ascending-dose assessment of eight lacnotuzumab doses (0.01-20 mg/kg); in part B (n = 16), lacnotuzumab was administered at either 5 or 10 mg/kg. In each study cohort, individuals were randomized 3:1 to lacnotuzumab or placebo. Lacnotuzumab was generally well tolerated. At higher doses (10 and 20 mg/kg), creatine kinase (CK) elevations (>5× the upper limit of normal, but asymptomatic and reversible) and mild transient periorbital swelling were reported. Most adverse events (AEs) were low-grade, no unexpected or novel AEs were observed, and there were no discontinuations for AEs. Free, unbound lacnotuzumab serum concentration-time profiles showed nonlinear PK across doses from 0.01 to 20 mg/kg, with faster apparent elimination at lower doses or concentrations; this finding was consistent with apparent target-mediated drug disposition. Lacnotuzumab also showed dose-dependent, on-target effects on multiple downstream biomarkers. Preclinical investigations of the CK elevation and periorbital swelling observed after lacnotuzumab administration suggest that these are reversible, nonpathological events linked to inhibition of the CSF-1 pathway. These data support further evaluation of lacnotuzumab in clinical studies.

New Strategies Using Antibody Combinations to Increase Cancer Treatment Effectiveness

Antibodies have proven their high value in antitumor therapy over the last two decades. They are currently being used as the first-choice to treat some of the most frequent metastatic cancers, like HER2⁺ breast cancers or colorectal cancers, currently treated with trastuzumab (Herceptin) and bevacizumab (Avastin), respectively. The impressive therapeutic success of antibodies inhibiting immune checkpoints has extended the use of therapeutic antibodies to previously unanticipated tumor types. These anti-immune checkpoint antibodies allowed the cure of patients devoid of other therapeutic options, through the recovery of the patient’s own immune response against the tumor. In this review, we describe how the antibody-based therapies will evolve, including the use of antibodies in combinations, their main characteristics, advantages, and how they could contribute to significantly increase the chances of success in cancer therapy. Indeed, novel combinations will consist of mixtures of antibodies against either different epitopes of the same molecule or different targets on the same tumor cell; bispecific or multispecific antibodies able of simultaneously binding tumor cells, immune cells or extracellular molecules; immunomodulatory antibodies; antibody-based molecules, including fusion proteins between a ligand or a receptor domain and the IgG Fab or Fc fragments; autologous or heterologous cells; and different formats of vaccines. Through complementary mechanisms of action, these combinations could contribute to elude the current limitations of a single antibody which recognizes only one particular epitope. These combinations may allow the simultaneous attack of the cancer cells by using the help of the own immune cells and exerting wider therapeutic effects, based on a more specific, fast, and robust response, trying to mimic the action of the immune system.

Immunomodulatory Monoclonal Antibodies in Combined Immunotherapy Trials for Cutaneous Melanoma

In the last few years, there has been a twist in cancer treatment toward immunotherapy thanks to the impressive results seen in advanced patients from several tumor pathologies. Cutaneous melanoma is a highly mutated and immunogenic tumor that has been a test field for the development of immunotherapy. However, there is still a way on the road to achieving complete and long-lasting responses in most patients. It is desirable that immunotherapeutic strategies induce diverse immune reactivity specific to tumor antigens, including the so-called neoantigens, as well as the blockade of immunosuppressive mechanisms. In this review, we will go through the role of promising monoclonal antibodies in cancer immunotherapy with immunomodulatory function, especially blocking of the inhibitory immune checkpoints CTLA-4 and PD-1, in combination with different immunotherapeutic strategies such as vaccines. We will discuss the rational basis for these combinatorial approaches as well as different schemes currently under study for cutaneous melanoma in the clinical trials arena. In this way, the combination of "push and release" immunomodulatory therapies can contribute to achieving a more robust and durable antitumor immune response in patients.

Toxicity profiles of immunotherapy

Immunotherapies are changing the landscape of advanced solid tumor treatment. These therapies have different mechanisms of action and include oncolytic viruses, checkpoint inhibitors, such as CTLA-4 or PD1/PD-L1 monoclonal antibodies, and CSF-1R antibodies. Given the growing therapeutic impact of these agents in oncology, it is important to better understand their properties. Immunotherapies generate new toxicity profiles that are called immune-related adverse events and require specific management. This review focuses on the mechanisms of action of such side effects, as well as their description and their general management.

New insights into the immunopathogenesis of systemic lupus erythematosus

The aetiology of systemic lupus erythematosus (SLE) is multifactorial, and includes contributions from the environment, stochastic factors, and genetic susceptibility. Great gains have been made in understanding SLE through the use of genetic variant identification, mouse models, gene expression studies, and epigenetic analyses. Collectively, these studies support the concept that defective clearance of immune complexes and biological waste (such as apoptotic cells), neutrophil extracellular traps, nucleic acid sensing, lymphocyte signalling, and interferon production pathways are all central to loss of tolerance and tissue damage. Increased understanding of the pathogenesis of SLE is driving a renewed interest in targeted therapy, and researchers are now on the verge of developing targeted immunotherapy directed at treating either specific organ system involvement or specific subsets of patients with SLE. Accordingly, this Review places these insights within the context of our current understanding of the pathogenesis of SLE and highlights pathways that are ripe for therapeutic targeting.

S2k guideline for treatment of cutaneous lupus erythematosus - guided by the European Dermatology Forum (EDF) in cooperation with the European Academy of Dermatology and Venereology (EADV)

Cutaneous lupus erythematosus (CLE) is a rare inflammatory autoimmune disease with heterogeneous clinical manifestations. To date, no therapeutic agents have been licensed specifically for patients with this disease entity, and topical and systemic drugs are mostly used 'off-label'. The aim of the present guideline was to achieve a broad consensus on treatment strategies for patients with CLE by a European subcommittee, guided by the European Dermatology Forum (EDF) and supported by the European Academy of Dermatology and Venereology (EADV). In total, 16 European participants were included in this project and agreed on all recommendations. Topical corticosteroids remain the mainstay of treatment for localized CLE, and further topical agents, such as calcineurin inhibitors, are listed as alternative first-line or second-line topical therapeutic option. Antimalarials are recommended as first-line and long-term systemic treatment in all CLE patients with severe and/or widespread skin lesions, particularly in patients with a high risk of scarring and/or the development of systemic disease. In addition to antimalarials, systemic corticosteroids are recommended as first-line treatment in highly active and/or severe CLE. Second- and third-line systemic treatments include methotrexate, retinoids, dapsone and mycophenolate mofetil or mycophenolate acid, respectively. Thalidomide should only be used in selected therapy-refractory CLE patients, preferably in addition to antimalarials. Several new therapeutic options, such as B-cell- or interferon α-targeted agents, need to be further evaluated in clinical trials to assess their efficacy and safety in the treatment of patients with CLE.

Early risk prognosis of free-flap transplant failure by quantitation of the macrophage colony-stimulating factor in patient plasma using 2-dimensional liquid-chromatography multiple reaction monitoring-mass spectrometry

Although great success of microvascular free-flap transplantation surgery has been achieved in recent years, between 1.5% and 15% of flaps are still lost due to vascular occlusion. The clinical challenge remains to salvage a transplant in the case of vascular complications. Since flap loss is devastating for the patient, it is of utmost importance to detect signs of complications or of conspicuities as soon as possible. Rescue success rates highly depend on early revision. In this study, we collected blood samples during transplantation surgery from either the contributory artery or the effluent vein of the flap and applied a targeted mass spectrometry-based approach to quantify 24 acute phase proteins, cytokines, and growth factors in 63 plasma samples from 21 hospitalized patients, generating a dataset with 9450 protein concentration values. Biostatistical analyses of the targeted plasma protein concentrations in all 63 plasma samples showed that venous concentrations of macrophage colony-stimulating factor (M-CSF) provided the highest accuracy for discriminating patients with either clinical conspicuities or complications from control individuals. Using 21.33 ng/mL of M-CSF as the diagnostic threshold when analyzing venous blood plasma samples, the assay obtained a sensitivity of 0.93 and a specificity of 0.85 with an area under the curve value of 0.902 in the receiver operating characteristic analysis. Overall, our results indicate that M-CSF is a potential molecular marker for early risk prognosis of free-flap transplant failure.