Nontuberculous mycobacterial infections in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation.

BACKGROUND: The incidence of mycobacterial infections in patients with hematologic malignancies and hematopoietic stem cell transplant (HSCT) recipients is increasing, contributing to significant mortality and morbidity. This review explores the epidemiology, risk factors, clinical presentation, diagnosis, and treatment of nontuberculous mycobacteria (NTM) in this population. METHODS: A literature search was performed using PubMed with keywords and MeSH terms pertaining to the topics of nontuberculous mycobacteria, hematologic malignancies, hematopoietic stem cell transplant, cellular therapies, chimeric antigen therapies, epidemiology, diagnosis, and treatment. Additionally, we examined the reference lists of the included articles to identify other pertinent studies. RESULTS: Diagnosing mycobacterial disease among patients with hematologic disease and treatment-associated immunosuppressive conditions is challenging due to the lack of distinctive clinical, radiographic, and laboratory markers, as well as the atypical manifestations compared to immunocompetent patients. Treatment involves using a combination of antibiotics for extended durations, coupled with strategies to achieve source control and reduce immunosuppression when feasible. This is complicated by the absence of clear data correlating in-vitro drug susceptibility and clinical outcome for many antimicrobials use to treat NTM, adverse drug-drug interactions, and the frequent challenges related to poor medication tolerability and toxicities. CONCLUSION: The rising incidence and corresponding clinical challenges of mycobacterial infections in this unique patient population necessitate a heightened awareness and familiarity of NTM disease by clinicians to achieve timely diagnosis and favorable treatment outcomes.

Clinical manifestations, treatment and outcomes of patients infected with Mycobacterium haemophilum with a focus on immune reconstitution inflammatory syndrome: a retrospective multi-site study.

BACKGROUND: Mycobacterium haemophilum is a nontuberculous mycobacterium with fastidious in vitro growth requirements and an increasingly reported cause of extrapulmonary disease. Timely diagnosis and management of M. haemophilum infections and the immune reconstitution inflammatory syndromes (IRIS) observed in a subset of patients during treatment remain challenging. METHODS: We conducted a retrospective chart review between January 1, 2010, and January 1, 2022 and identified 26 patients diagnosed with M. haemophilum infection at our institution. We describe their clinical presentation, diagnostic results, management, and outcomes. RESULTS: The majority of patients in our cohort had upper and/or lower extremity skin involvement, were immunosuppressed, and had generally favourable treatment outcomes. All tested M. haemophilum isolates were susceptible in vitro to clarithromycin and trimethoprim-sulfamethoxazole. Moreover, high rates of susceptibility were noted for ciprofloxacin (95%), linezolid (90%), and rifampin (85%). IRIS was identified in 31% of cases and should be considered in patients who develop worsening skin lesions or systemic symptoms following the initiation of effective antimicrobial therapy. Visualisation of acid-fast bacilli on initial tissue stains, a positive mycobacterial blood culture, and rapid de-escalation of tumour necrosis factor-α inhibitors and/or corticosteroids were more frequently encountered among patients in our cohort who developed IRIS. CONCLUSION: M. haemophilum infection should be considered among patients receiving immunomodulatory therapy who develop discoloured or nodular skin lesions involving the extremities, worsening focal arthritis, tenosynovitis, or isolated adenopathy. A heightened awareness of this pathogen's clinical and laboratory characteristics can lead to a timely diagnosis and favourable outcome.

Feasibility of the A-STEP for the assessment of exercise capacity in people with cystic fibrosis.

OBJECTIVES: To evaluate feasibility of the Alfred Step Test Exercise Protocol (A-STEP) for the assessment of exercise capacity in adults and children with cystic fibrosis (CF); in adults to test whether demographics and/or lung function correlated with exercise capacity. METHODS: Adults and children with stable CF from two centres completed the A-STEP (a recently developed incremental maximal-effort step test). Feasibility was evaluated by: usefulness for exercise capacity assessment (measures of exercise capacity were: level reached, exercise-induced desaturation, and achievement of at least one maximal effort criteria); safety; operational factors; time to complete; floor and/or ceiling effects. We used multiple linear regression to test whether demographics and/or lung function correlated with exercise capacity. RESULTS: A total of 49 participants: 38 adults (18 male), percent predicted (pp) forced expiration in one second (FEV1 ) 29-109, aged 22-48 years and 11 children (6 male), ppFEV1 68-107, aged 10-15 years were included. Levels reached (mean (SD) [range]) were 10.2 (2.4) [6-15] (adults), 10.1 (2.5) [7-14] (children); desaturation (change between baseline and peak-exercise SpO2 ): was 8.4 (3.8 [0-15]% (adults), 2.0 (2.0) [0-7]% (children). A total of 8 (21%) adults and no children desaturated <90% SpO2 . At least one criterion for maximal effort was reached by 33 (84%) adults and 10 (91%) children. There were no adverse events. The A-STEP was straightforward to use and carried out by one operator. A total of 26 (68.4%) adults and 7 (63.6%) children completed the test within the recommended 8-12 min. All participants completed a minimum of 6 levels, and completed the test before the final 16th level. In adults, ppFEV1 and ppFVC correlated with the level reached (r = 0.55; p = <0.001 and r = 0.66, p = <0.0001) and desaturation (r = 0.55, p = <0.001 and r = 0.45, p = <0.005). CONCLUSION: In adults and children with stable CF, the A-STEP was feasible, safe, and operationally easy to use for the assessment of exercise capacity, without floor or ceiling effects. In adults, lung function correlated with exercise capacity.

Development of the A-STEP: A new incremental maximal exercise capacity step test in cystic fibrosis.

BACKGROUND: Exercise testing is important in people with cystic fibrosis (pwCF). The aim was to develop an incremental maximal step test to assess exercise capacity across the range of pwCF, without floor or ceiling effects, within restrictions of space, and infection prevention. METHODS: The step test was developed in adults with stable CF. Subjects assisted in selecting: step height, start rate, increments, stage and test duration parameters. Equipment to externally pace and time the test and measure exercise parameters were selected. Reasons for stopping, criteria for achieving a maximal test, and key outcome measures were determined. Documentation to record and standardize the test and instructions to set up the metronome and timer App were developed. Infection control practices were considered. RESULTS: Eight subjects were recruited to develop the Alfred Step Test Exercise Protocol (A-STEP) on a 20 cm portable step. The A-STEP package included a pretest information sheet, clinical assessment and instructions, recording worksheet, and the metronome/timer instructions. The test started at 18 steps/min. Each level increased by two steps/min to a maximum of 48 steps (Level 16). Results were presented as mean (SD) [range] for: age 30.63 (5.89) [21-39] years; FEV1 58.13 (18.33) [32-89]%; levels: 10.31 (3.29) [6-15.5]. The A-STEP required space of 2 m2 and complied with current infection control guidelines. CONCLUSIONS: The A-STEP is a new incremental maximal step test to assess exercise capacity in pwCF, without floor or ceiling effects. It addresses the issues of space restrictions and the need for strict infection prevention in the clinical setting.

The AWESCORE, a patient-reported outcome measure: development, feasibility, reliability, validity and responsiveness for adults with cystic fibrosis.

BACKGROUND: Quality of life has improved dramatically over the past two decades in people with cystic fibrosis (CF). Quantification has been enabled by patient-reported outcome measures (PROMs); however, many are lengthy and can be challenging to use in routine clinical practice. We propose a short-form PROM that correlates well with established quality-of-life measures. METHODS: We evaluated the utility of a 10-item score (AWESCORE) by measuring reliability, validity and responsiveness in adults with CF. The questions were developed by thematic analysis of survey questions to patients in a single adult CF centre. Each question was scored using a numerical rating scale 0 to 10. Total scores ranged from 0 to 100. Test-retest reliability was assessed over 24 h. To determine validity, comparisons were sought between stable subjects and those in pulmonary exacerbation, and between AWESCORE and Cystic Fibrosis Questionnaire - Revised (CFQ-R). Responsiveness to pulmonary exacerbation in individual subjects was evaluated. RESULTS: Five domains, each with two questions, were identified for respiratory, physical, nutritional, psychological and general health. A total of 246 consecutive adults attending the outpatient clinic completed the AWESCORE. Scores were higher during clinical stability compared to pulmonary exacerbation (mean± sd): 73±11 versus 48±11 (p<0.001). Each domain scored worse during an acute exacerbation (p<0.001). No differences in reliability were observed in scores on retesting using Bland-Altman comparison. The CFQ-R scores (mean±sd: 813±125) and AWESCORE (81±13) were moderately correlated (Pearson's r=0.649; p=0.002). CONCLUSIONS: The AWESCORE is valid, reliable and responsive to altered health status in CF.

Updated Experience of Mycobacterium chimaera Infection: Diagnosis and Management in a Tertiary Care Center.

BACKGROUND: Despite safety communications from the Food and Drug Administration (FDA) regarding the outbreak of Mycobacterium chimaera infections (MCIs) from contaminated heater-cooler devices, new cases continue to be identified. METHODS: We retrospectively reviewed confirmed cases of MCI that were managed at Mayo Clinic sites (Arizona, Florida, and Minnesota) from 09/2015 to 01/2021. Clinical histories including prior cardiovascular surgery were recorded. Diagnostic workup including ophthalmologic examination, imaging, and laboratory testing was reviewed. Treatment and survival outcomes on follow-up were obtained. RESULTS: Twelve patients with MCI were included. All patients had aortic valve or graft replacement. Five patients had their surgical procedures following the 10/15/2015 FDA safety communication. The mean time from surgery to symptom onset (range) was 32 (13-73) months. Ten of 11 patients who underwent ophthalmologic examination had chorioretinal abnormalities. Three patients who underwent microbial cell-free deoxyribonucleic acid sequencing tested positive for M. chimaera, which was subsequently confirmed with blood culture growth. Echocardiography and positron emission tomography/computed tomography (PET/CT) revealed evidence of prosthetic valve/graft infection in 7/12 (58.3%) and 6/10 (60.0%) of cases, respectively. Seven patients (58.3%) underwent redo cardiovascular surgery. Of these, 1 patient died 2 days postdischarge, 1 experienced spinal osteomyelitis relapse, and another had interval prosthetic valve fluorodeoxyglucose (FDG) uptake on PET/CT suspicious for recurrent infection. Among 4 patients on medical therapy only, 3 expired or transitioned to hospice during follow-up. CONCLUSIONS: MCI continues to occur despite the FDA communications. Incorporation of ophthalmologic examination and use of advanced tools may improve MCI diagnosis. The mortality in these patients is high even with aggressive surgical/medical management.

Lumacaftor/ivacaftor-associated health stabilisation in adults with severe cystic fibrosis.

INTRODUCTION: Lumacaftor/ivacaftor (LUM/IVA) has been shown to improve clinical outcomes in cystic fibrosis (CF) patients homozygous for Phe508del with forced expiratory volume in 1 s (FEV1) % pred >40%. We assessed the clinical utility of LUM/IVA in all eligible adult CF patients with FEV1 % pred <40% treated for at least 1 year under a single-centre managed access programme. METHODS: Following clinical optimisation, eligible patients (n=40) with FEV1 % pred <40% were commenced on LUM/IVA and monitored for tolerance and clinical outcomes, including health service utilisation, pulmonary function, weight and body composition. 24 patients reached 1 year of treatment by the time of evaluation. Six patients discontinued due to adverse events (five for increased airways reactivity) and three underwent lung transplantation. RESULTS: In comparison with the year prior to LUM/IVA commencement, significant reductions (median per year) were observed in the treatment year in the number of pulmonary exacerbations requiring hospitalisation (from 3 to 1.5; p=0.0002), hospitalisation days (from 27 to 17; p=0.0002) and intravenous antibiotic (IVAB) usage days (from 45 to 27; p=0.0007). Mean±sd change in FEV1 % pred was -2.10±1.18% per year in the year prior, with the decline reversed in the year following (+1.45±1.13% per year; p=0.035), although there was significant heterogeneity in individual responses. Mean±sd weight gain at 1 year was 2.5±4.1 kg (p=0.0007), comprising mainly fat mass (mean 2.2 kg). The proportion of patients severely underweight (body mass index <18.5 kg·m-2) decreased from 33% at baseline to 13% at 1 year (p=0.003). CONCLUSION: This real-world evaluation study demonstrated benefits over several clinical domains (infective exacerbations requiring hospitalisation, IVABs, pulmonary function decline and nutritional parameters) in CF patients with severe lung disease.

Body composition and weight changes after ivacaftor treatment in adults with cystic fibrosis carrying the G551 D cystic fibrosis transmembrane conductance regulator mutation: A double-blind, placebo-controlled, randomized, crossover study with open-label extension.

OBJECTIVES: In patients with cystic fibrosis (CF) who carry the G551D mutation, treatment with ivacaftor improves lung function and weight; however, short- and long-term impacts on body composition have not been well studied. METHODS: Twenty adults with CF carrying the G551D mutation (mean ± standard deviation body mass index [BMI] 23.3 ± 4.3 kg/m2) were recruited for a single-center, double-blind, placebo-controlled, 28-d, crossover study of ivacaftor, followed by an open-label extension (OLE) for 5 mo. Eleven patients underwent measurements 2 y later. The study variables included weight, BMI, and body composition (including fat-free mass [FFM] and fat mass). RESULTS: After 28 d of treatment with ivacaftor, weight increased by 1.1 ± 1.3 kg, BMI by 0.4 ± 0.5 kg/m2, and FFM by 1.1 ± 1.2 kg (all P < .005) with no change in fat mass. Differences between 28-d changes on ivacaftor and placebo were not statistically significant. In the following 5 mo of the OLE, there were significant increases in weight (1.2 ± 1.9 kg; P < .05) and fat mass (1.5 ± 1.9 kg; P < .01), but not in FFM. Between baseline and the end of the OLE, the total weight gain was 2.5 ± 2.4 kg (P < .005), comprised of 0.9 ± 1.5 kg FFM (P < .05) and 1.6 ± 1.8 kg fat mass (P < .005). For the 11 participants who were followed for a further 2 y, no further changes in mean weight, BMI, or body composition parameters between 6 mo and 2 y later were observed. CONCLUSIONS: Small gains were seen in FFM in the first month of ivacaftor treatment. Weight, BMI, and fat-mass gains in the first 6 mo on ivacaftor plateaued by 2.5 y. The metabolic and clinical consequences of weight and fat-mass gains remain to be determined.

Treatment of Drug-Resistant Tuberculosis. An Official ATS/CDC/ERS/IDSA Clinical Practice Guideline.

Background: The American Thoracic Society, U.S. Centers for Disease Control and Prevention, European Respiratory Society, and Infectious Diseases Society of America jointly sponsored this new practice guideline on the treatment of drug-resistant tuberculosis (DR-TB). The document includes recommendations on the treatment of multidrug-resistant TB (MDR-TB) as well as isoniazid-resistant but rifampin-susceptible TB.Methods: Published systematic reviews, meta-analyses, and a new individual patient data meta-analysis from 12,030 patients, in 50 studies, across 25 countries with confirmed pulmonary rifampin-resistant TB were used for this guideline. Meta-analytic approaches included propensity score matching to reduce confounding. Each recommendation was discussed by an expert committee, screened for conflicts of interest, according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology.Results: Twenty-one Population, Intervention, Comparator, and Outcomes questions were addressed, generating 25 GRADE-based recommendations. Certainty in the evidence was judged to be very low, because the data came from observational studies with significant loss to follow-up and imbalance in background regimens between comparator groups. Good practices in the management of MDR-TB are described. On the basis of the evidence review, a clinical strategy tool for building a treatment regimen for MDR-TB is also provided.Conclusions: New recommendations are made for the choice and number of drugs in a regimen, the duration of intensive and continuation phases, and the role of injectable drugs for MDR-TB. On the basis of these recommendations, an effective all-oral regimen for MDR-TB can be assembled. Recommendations are also provided on the role of surgery in treatment of MDR-TB and for treatment of contacts exposed to MDR-TB and treatment of isoniazid-resistant TB.

Advances in space radiation physics and transport at NASA.

The space radiation environment is a complex mixture of particle types and energies originating from sources inside and outside of the galaxy. These environments may be modified by the heliospheric and geomagnetic conditions as well as planetary bodies and vehicle or habitat mass shielding. In low Earth orbit (LEO), the geomagnetic field deflects a portion of the galactic cosmic rays (GCR) and all but the most intense solar particle events (SPE). There are also dynamic belts of trapped electrons and protons with low to medium energy and intense particle count rates. In deep space, the GCR exposure is more severe than in LEO and varies inversely with solar activity. Unpredictable solar storms also present an acute risk to astronauts if adequate shielding is not provided. Near planetary surfaces such as the Earth, moon or Mars, secondary particles are produced when the ambient deep space radiation environment interacts with these surfaces and/or atmospheres. These secondary particles further complicate the local radiation environment and modify the associated health risks. Characterizing the radiation fields in this vast array of scenarios and environments is a challenging task and is currently accomplished with a combination of computational models and dosimetry. The computational tools include models for the ambient space radiation environment, mass shielding geometry, and atomic and nuclear interaction parameters. These models are then coupled to a radiation transport code to describe the radiation field at the location of interest within a vehicle or habitat. Many new advances in these models have been made in the last decade, and the present review article focuses on the progress and contributions made by workers and collaborators at NASA Langley Research Center in the same time frame. Although great progress has been made, and models continue to improve, significant gaps remain and are discussed in the context of planned future missions. Of particular interest is the juxtaposition of various review committee findings regarding the accuracy and gaps of combined space radiation environment, physics, and transport models with the progress achieved over the past decade. While current models are now fully capable of characterizing radiation environments in the broad range of forecasted mission scenarios, it should be remembered that uncertainties still remain and need to be addressed.

Standardizing Febrile Neutropenia Management: Antimicrobial Stewardship in the Hematologic Malignancy Population.

Patients with febrile neutropenia (FN) often are subject to antibiotic and diagnostic test overuse. We sought to improve appropriate use of antimicrobials and diagnostic tests for patients with FN. We used a blended quality approach with Lean Six Sigma tools and iterative improvement of a clinical decision aid to guide providers through empirical antimicrobial selection and diagnostic evaluation of patients with FN during a yearlong period. We evaluated the incidence of nonadherence to best practice before, during, and after rollout of a clinical decision aid in conjunction with an educational initiative. At baseline, 71% of patients with FN had at least one critical deviation from best practice. During the project, the percentage decreased to 27.3%; 4 months after the project was completed, the percentage was 33.3% (P = .04). A clinical decision aid can improve adherence to best practices for the empirical management of FN.

Postoperative Hardware-Related Infection from Kytococcus schroeteri: Its Association with Prosthetic Material and Hematological Malignancies-A Report of a Case and Review of Existing Literature.

INTRODUCTION: Kytococcus schroeteri is an infrequently isolated Gram-positive coccus often encountered as a commensal bacterium. Only eighteen cases of human infection associated with this organism have been previously reported. Most of these cases involved patients with implanted prosthetic materials or patients with immunosuppressive conditions. It has been described in prosthetic valve endocarditis and in select patients with hematologic diseases but only one prior report as being involved in osteoarticular infections. CASE PRESENTATION: We describe a case of postsurgical osteoarticular hardware-related infection by K. schroeteri and discuss a possible association with implanted prosthetic material. CONCLUSION: Other clinical presentations of K. schroeteri, including reported infection syndromes, antimicrobial susceptibility profiles, and treatment outcomes, are also reviewed.

Subclinical Left Ventricular Dysfunction is Influenced by Genotype Severity in Patients with Cystic Fibrosis.

BACKGROUND AND OBJECTIVE: Over 2000 genotypes in the cystic fibrosis (CF) gene have been described. These genotypic differences result in variable clinical manifestations of CF, with severity of disease dependent on CF transmembrane conductance (CFTR) protein function. CFTR is widely distributed in nucleated cells, including cardiac myocytes, but the effect of genotype on cardiac function is not known. METHODS: This retrospective review of echocardiographic data is from a single adult CF centre between 2000 and 2015. Patients were cohorted based on the functional classification of genotype. 'Severe' patients had both CF genes from functional classification groups 1-3; 'mild' patients had one or no gene from these groups, or in the event of the second gene being unknown were pancreatic sufficient. RESULTS: Genotype and echocardiography were recorded during the inclusion period in 100 patients, 79 of whom were classified as having severe genotypes. Although the severe group were younger they had a lower fractional shortening (33.66 ± 6.6 vs 36.9 ± 6.3, P < .05), left atrial area (14.9 ± 3.6 versus 18.0 ± 4.2 cm2; P < .01) and volume (39.9 ± 18.7 versus 51.0 ± 18.7 mL; P < .05) and showed a trend to lower left ventricular ejection fraction. CONCLUSIONS: This study is the first to show that in CF, severity of genotype (functional classification) is associated with cardiac impairment. Patients with severe CF genotype and cardiac dysfunction should be identified to evaluate cardiac response to gene-modifying treatments prior to consideration for lung transplantation.

Accumulating physical activity in at least 10-minute bouts predicts better lung function after 3-years in adults with cystic fibrosis.

Achieving physical activity guidelines by undertaking multiple bouts of moderate-vigorous physical activity ≥10 min duration, but not shorter periods of activity, was independently associated with less decline in FEV1over 3 years among adults with CF http://ow.ly/yk6930ivCV8.

The potentially beneficial central nervous system activity profile of ivacaftor and its metabolites.

Ivacaftor-lumacaftor and ivacaftor are two new breakthrough cystic fibrosis transmembrane conductance modulators. The interactions of ivacaftor and its two metabolites hydroxymethylivacaftor (iva-M1) and ivacaftorcarboxylate (iva-M6) with neurotransmitter receptors were investigated in radioligand binding assays. Ivacaftor displayed significant affinity to the 5-hydroxytryptamine (5-HT; serotonin) 5-HT2C receptor (pKi=6.06±0.03), ß3-adrenergic receptor (pKi=5.71±0.07), δ-opioid receptor (pKi=5.59±0.06) and the dopamine transporter (pKi=5.50±0.20); iva-M1 displayed significant affinity to the 5-HT2C receptor (pKi=5.81±0.04) and the muscarinic M3 receptor (pKi=5.70±0.10); iva-M6 displayed significant affinity to the 5-HT2A receptor (pKi=7.33±0.05). The in vivo central nervous system activity of ivacaftor (40 mg·kg-1 intraperitoneally for 21 days) was assessed in a chronic mouse model of depression. In the forced swim test, the ivacaftor-treated group displayed decreased immobility (52.8±7.6 s), similarly to fluoxetine (33.8±11.0 s), and increased climbing/swimming activity (181.5±9.2 s). In the open field test, ivacaftor produced higher locomotor activity than the fluoxetine group, measured both as mean number of paw touches (ivacaftor 81.1±9.6 versus fluoxetine 57.9±9.5) and total distance travelled (ivacaftor 120.6±16.8 cm versus fluoxetine 84.5±16.0 cm) in 600 s. Treatment of 23 cystic fibrosis patients with ivacaftor-lumacaftor resulted in significant improvements in quality of life (including anxiety) in all five domains of the AweScoreCF questionnaire (p=0.092-0.096). Our findings suggest ivacaftor displays potential clinical anxiolytic and stimulating properties, and may have beneficial effects on mood.

Mycobacterium genavense infections in non-HIV immunocompromised hosts: a systematic review.

BACKGROUND: Mycobacterium genavense is a non-tuberculous mycobacterium which can rarely cause disease in non-HIV immunocompromised hosts. We describe our experience with this unusual infection and perform a systematic review of the literature to describe the features of M. genavense infection in non-HIV immunocompromised hosts. METHODS: All cases of Mycobacterium genavense infection in non-HIV patients at our institution were reviewed. In addition, we conducted a systematic review of the literature to identify previously published cases of M. genavense infections in non-HIV hosts. FINDINGS: Two cases of M. genavense were identified at our center; a 51-year-old renal transplant recipient with a prosthetic knee joint infection and a 66-year-old woman with idiopathic CD4 lymphocytopenia with gastrointestinal tract disease. The systematic review identified 44 cases of M. genavense infection in non-HIV hosts. The most common underlying conditions were solid organ transplantation (40%), sarcoidosis (14%) and hematopoietic stem cell transplantation (7%). Disease most commonly involved the gastrointestinal tract, spleen, liver or bone marrow. Diagnosis was challenging with PCR required for identification in nearly all cases. Over one-third of patients died, which may reflect the combination of infection and underlying comorbidities. Overall cure was achieved in 61% with a mean duration of antimycobacterial therapy of 15.5 months (range 10-24). CONCLUSION: M. genavense infection is a rare mycobacterial infection in non-HIV immunocompromised hosts. It should be suspected in immunocompromised patients presenting with disseminated mycobacterial infection, acid fast bacilli on smear or histopathologic examination, with poor or no growth in mycobacterial cultures.

Development of HPLC and LC-MS/MS methods for the analysis of ivacaftor, its major metabolites and lumacaftor in plasma and sputum of cystic fibrosis patients treated with ORKAMBI or KALYDECO.

ORKAMBI (ivacaftor-lumacaftor [LUMA]) and KALYDECO (ivacaftor; IVA) are two new breakthrough cystic fibrosis (CF) drugs that directly modulate the activity and trafficking of the defective CFTR underlying the CF disease state. Currently, no therapeutic drug monitoring assays exist for these very expensive, albeit, important drugs. In this study, for the first time HPLC and LC-MS methods were developed and validated for rapid detection and quantification of IVA and its major metabolites hydroxymethyl-IVA M1 (active) and IVA-carboxylate M6 (inactive); and LUMA in the plasma and sputum of CF patients. With a mobile phase consisting of acetonitrile/water:0.1% formic acid (60:40v/v) at a flow rate of 1mL/min, a linear correlation was observed over a concentration range from 0.01 to 10µg/mL in human plasma (IVA R2>0.999, IVA M1 R2>0.9961, IVA M6 R2>0.9898, LUMA R2>0.9954). The assay was successfully utilized to quantify the concentration of LUMA, IVA, M1 and M6 in the plasma and sputum of CF patients undergoing therapy with KALYDECO (IVA 150mg/q12h) or ORKAMBI (200mg/q12h LUMA-125mg/q12h IVA). The KALYDECO patient exhibited an IVA plasma concentration of 0.97µg/mL at 2.5h post dosage. M1 and M6 plasma concentrations were 0.50µg/mL and 0.16µg/mL, respectively. Surprisingly, the ORKAMBI patient displayed very low plasma concentrations of IVA (0.06µg/mL) and M1 (0.07µg/mL). The M6 concentrations (0.15µg/mL) were comparable to those of the KALYDECO patient. However, we observed a relatively high plasma concentration of LUMA (4.42µg/mL). This reliable and novel method offers a simple and sensitive approach for therapeutic drug monitoring of KALYDECO and ORKAMBI in plasma and sputum. The introduction of the assay into the clinical setting will facilitate pharmacokinetics/pharmacodynamic analysis and assist clinicians to develop more cost effective and efficacious dosage regimens for these breakthrough CF drugs.