Exposure-response relationship of cabozantinib in patients with metastatic renal cell carcinoma treated in routine care.

BACKGROUND: Interindividual pharmacokinetic variability may influence the clinical benefit or toxicity of cabozantinib in metastatic renal cell carcinoma (mRCC). We aimed to investigate the exposure-toxicity and exposure-response relationship of cabozantinib in unselected mRCC patients treated in routine care. METHODS: This ambispective multicenter study enrolled consecutive patients receiving cabozantinib in monotherapy. Steady-state trough concentration (Cmin,ss) within the first 3 months after treatment initiation was used for the PK/PD analysis with dose-limiting toxicity (DLT) and survival outcomes. Logistic regression and Cox proportional-hazards models were used to identify the risk factors of DLT and inefficacy in patients, respectively. RESULTS: Seventy-eight mRCC patients were eligible for the statistical analysis. Fifty-two patients (67%) experienced DLT with a median onset of 2.1 months (95%CI 0.7-8.2). In multivariate analysis, Cmin,ss was identified as an independent risk factor of DLT (OR 1.46, 95%CI [1.04-2.04]; p = 0.029). PFS and OS were not statistically associated with the starting dose (p = 0.81 and p = 0.98, respectively). In the multivariate analysis of PFS, Cmin, ss > 336 ng/mL resulted in a hazard ratio of 0.28 (95%CI, 0.10-0.77, p = 0.014). By contrast, Cmin, ss > 336 ng/mL was not statistically associated with longer OS. CONCLUSION: Early plasma drug monitoring may be useful to optimise cabozantinib treatment in mRCC patients treated in monotherapy, especially in frail patients starting at a lower than standard dose.

The Effect of Concomitant Proton Pump Inhibitor and Cabozantinib on the Outcomes of Patients with Metastatic Renal Cell Carcinoma.

INTRODUCTION: Cabozantinib is an oral tyrosine kinase inhibitor that is approved for the treatment of metastatic renal cell carcinoma (mRCC). Cabozantinib is a weak base that exhibits a pH-dependent solubility profile in vitro which raises concerns about its bioavailability in patients treated with proton pump inhibitors (PPIs). The purpose of this study was to investigate whether PPI use has an impact on the efficacy, safety, and residual concentration (Ctrough) of cabozantinib in patients with mRCC. MATERIALS AND METHODS: This is a retrospective review of a prospectively collected electronic database of patients with mRCC who received cabozantinib at Gustave Roussy between February 2014 and December 2018. The Kaplan-Meier method was used for survival analysis and the Cox proportional-hazard model for uni- and multivariate analysis. In parallel, we conducted a pharmacokinetic study of cabozantinib in a distinct cohort of 50 mRCC patients, in which cabozantinib Ctrough was assayed using a validated tandem mass spectrometry-liquid chromatography method. RESULTS: We identified 99 patients treated with cabozantinib, including 43 patients being PPI users. With a median follow-up of 30.3 months, PPI users showed similar progression-free survival and overall survival outcomes compared with PPI nonusers. Similarly, the incidence of adverse events was not significantly different between the PPI users and nonusers, although PPI users required dose reductions more often. In the independent pharmacokinetic cohort, of whom 21 received PPI concomitantly, Ctrough was similar between the two groups. CONCLUSION: In line with the pharmacologic data, the concomitant use of PPI does not significantly impact the efficacy or safety of cabozantinib in patients with mRCC. IMPLICATIONS FOR PRACTICE: Drug interactions, especially between targeted therapies and proton pump inhibitors (PPI), were shown to potentially impact the outcomes of cancer patients. Cabozantinib, a current therapeutic standard in metastatic renal cell carcinoma (mRCC), exhibits a pH-dependent solubility profile, which raises concerns about its bioavailability in patients treated with proton pump inhibitors (PPI). At the present time, there is no evidence regarding the effect of PPIs on cabozantinib's efficacy and safety in patients with mRCC. This study found that the concomitant use of PPI during cabozantinib treatment in mRCC patients does not appear to impact the residual concentration, efficacy, and safety of cabozantinib in a real-life context.

Development and Validation of a Fast Ultra-High Performance Liquid Chromatography-Fluorescent Method for the Quantification of Hydroxychloroquine and Its Metabolites in Patients With Lupus.

BACKGROUND: Hydroxychloroquine (HCQ) is approved for the treatment of systemic lupus erythematosus (SLE). Therapeutic drug monitoring of HCQ is necessary to detect nonadherence and to improve treatment efficacy in patients with SLE. Liquid chromatographic-tandem mass spectroscopy and high performance liquid chromatography (HPLC)-fluorescent methods are currently used to measure whole blood concentrations of HCQ and its 2 main metabolites desethylhydroxychloroquine and desethylchloroquine in patients with SLE. This study reports the development and validation of an ultra-HPLC (U-HPLC) method with fluorescence detection for the simultaneous quantification of HCQ and its metabolites in whole blood. METHODS: After adding chloroquine (internal standard) to the samples, a single-step protein precipitation and a subsequent filtration were used for blood sample preparation. Analytes were separated under isocratic elution on a U-HPLC RP18 column with a total run time of 7 minutes. The mobile phase consisted of piperazine buffer (46.4 mM, pH = 9.8) and acetonitrile (68:32, vol/vol), which was delivered at a flow rate of 0.4 mL/min. Fluorescence excitation and emission wavelengths were 335 and 390 nm, respectively. Assay performance parameters were evaluated per FDA bioanalytical guidelines. RESULTS: The calibration curve was linear from 125 to 4000 ng/mL for HCQ. The lower limit of quantification was 10 ng/mL for all analytes. For HCQ, desethylchloroquine, and desethylhydroxychloroquine, accuracies and imprecisions ranged from -7.90% to 7.85% and 1.14% to 8.78%, respectively. CONCLUSIONS: A sensitive, accurate, and fast U-HPLC-fluorescent method was validated and successfully applied to quantify whole blood concentrations to perform therapeutic drug monitoring of HCQ in pediatric and adult lupus patients.

Tyrosine kinase inhibitors in cancers: Treatment optimization - Part I.

A multitude of TKI has been developed and approved targeting various oncogenetic alterations. While these have provided improvements in efficacy compared with conventional chemotherapies, resistance to targeted therapies occurs. Mutations in the kinase domain result in the inability of TKI to inactivate the protein kinase. Also, gene amplification, increased protein expression and downstream activation or bypassing of signalling pathways are commonly reported mechanisms of resistance. Improved understanding of mechanisms involved in TKI resistance has resulted in the development of new generations of targeted agents. In a race against time, the search for new, more potent and efficient drugs, and/or combinations of drugs, remains necessary as new resistance mechanisms to the latest generation of TKI emerge. This review examines the various generations of TKI approved to date and their common mechanisms of resistance, focusing on TKI targeting BCR-ABL, epidermal growth factor receptor, anaplastic lymphoma kinase and BRAF/MEK tyrosine kinases.

Phase 1 first-in-human dose-escalation study of ANV419 in patients with relapsed/refractory advanced solid tumors.

Patients with advanced cancer, previously treated with immune checkpoint blockade therapy, may retain residual treatment when undergoing the initial infusion of experimental monotherapy in phase 1 clinical trials. ANV419, an antibody-cytokine fusion protein, combines interleukin-2 (IL-2) with an anti-IL-2 monoclonal antibody, aiming to stimulate the expansion of CD8 T and natural killer lymphocytes while restricting regulatory T lymphocytes. In the recent publication of the phase 1 dose escalation study of ANV419, a notable gap exists in detailed information regarding patients' prior antitumoral treatments, specifically programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) targeted monoclonal antibodies. Some patients likely retained residual anti-PD-1/PD-L1 monoclonal antibodies, potentially influencing the outcomes of ANV419. In a separate clinical cohort, we retrospectively measured the residual concentration of nivolumab and pembrolizumab, revealing persistent serum concentrations of anti-PD-1/PD-L1 antibodies even months after treatment cessation. This underscores the importance of comprehensively documenting prior immunotherapy details in clinical trials. Such information is crucial for understanding potential interactions that may impact both immunological and clinical effects.

Tyrosine kinase inhibitors in cancers: Treatment optimization - Part II.

Real-life populations are more heterogeneous than those included in prospective clinical studies. In cancer patients, comorbidities and co-medications favor the appearance of severe adverse effects which can significantly impact quality of life and treatment effectiveness. Most of tyrosine kinase inhibitors (TKI) have been developed with flat oral dosing exposing patients to the risk of poor adherence due to side effects. Additionally, genetic or physiological factors, differences in diet, and drug-drug interactions can lead to inter-individual variability affecting treatment outcomes and increasing the risk of adverse events. Knowledge of the different factors of variability allows individualized patient management. This review examines the effects of adherence, food intake, and pharmaceutical form on the pharmacokinetics of oral TKI, as well as evaluating pharmacokinetics considerations improving TKI management. Concentration-effectiveness and concentration-toxicity data are presented for the selected TKI, and a simple therapeutic drug monitoring schema is outlined to help individualize dosing of oral TKI.

A Score to Predict the Clinical Usefulness of Therapeutic Drug Monitoring: Application to Oral Molecular Targeted Therapies in Cancer.

Therapeutic drug monitoring (TDM) involves measuring and interpreting drug concentrations in biological fluids to adjust drug dosages. In onco-hematology, TDM guidelines for oral molecular targeted therapies (oMTTs) are varied. This study evaluates a quantitative approach with a score to predict the clinical usefulness of TDM for oMTTs. We identified key parameters for an oMTT's suitability for TDM from standard TDM recommendations. We gathered oMTT pharmacological data, which covered exposure variability (considering pharmacokinetic (PK) impact of food and proton pump inhibitors), technical intricacy (PK linearity and active metabolites), efficacy (exposure-response relationship), and safety (maximum tolerated dose, and exposure-safety relationship). To assess the validity and the relevance of the score and define relevant thresholds, we evaluated molecules with prospective validation or strong recommendations for TDM, both in oncology and in other fields. By September 1, 2021, the US Food and Drug Administration (FDA) approved 67 oMTTs for onco-hematological indications. Scores ranged from 15 (acalabrutinib) to 80 (sunitinib) with an average of 48.3 and a standard deviation of 15.6. Top scorers included sunitinib, sorafenib, cabozantinib, nilotinib, and abemaciclib. Based on scores, drugs were categorized into low (< 40), intermediate (≥ 40 and < 60), and high (≥ 60) relevance for TDM. Notably, negative controls generally scored around or under 40, whereas positive controls had a high score across different indications. In this work, we propose a quantitative and reproducible score to compare the potential usefulness of TDM for oMTTs. Future guidelines should prioritize the TDM for molecules with the highest score.

Management of Pain Medication in Patients With a History of Bariatric Surgery: A Systematic Review.

CONTEXT: Obesity prevalence is persistently increasing worldwide. Among surgical therapeutic procedures, bypass surgery and sleeve gastrectomy have shown the best results regarding weight loss, prevention, and treatment of secondary complications. However, these surgeries are associated with an increased risk of malabsorption and metabolic changes that could further affect the pharmacokinetics of drugs. On the other hand, patients with a history of such surgeries are more likely to experience pain and request analgesic initiation or adaptation. The question of how to manage pain medication in these patients is challenging due to their narrow therapeutic indexes. OBJECTIVES: To summarize the current literature on the impact of bariatric surgery on the subsequent pharmacokinetics of analgesics and propose a multidisciplinary therapeutic attitude to optimize pain management in these patients. METHODS: We conducted a systematic review that included all pharmacological studies published after 2000. RESULTS: Unexpectedly, these surgeries seem to increase the bioavailability of drugs by long-term improvement of hepatic function. Yet, the medical community drastically lacks robust guidelines for pain management in those patients. This systematic review aims to bring together pharmacological studies related to the use of pain treatments in patients who underwent bypass surgery or sleeve gastrectomy. CONCLUSIONS: Caution should be exercised regarding the risk of overdose in every circumstance: treatment initiation, change of doses, or change of molecule. More prospective trials comparing the pharmacokinetics of medications in obese patients with and without prior bariatric surgery are needed.

Breast cancer survivors' opinion on personalizing endocrine therapy and developing informative tools.

Understanding breast cancer survivors' perspectives is critical to personalizing endocrine therapy (ET) in the adjuvant setting. A nationwide survey among breast cancer survivors was proposed in France, in collaboration with patient advocacy organizations, to assess their perspectives on personalizing ET and developing dedicated informative tools. This survey explored patients' preferences regarding ET intake schedule, formulation, presentation (color, taste, shape, size, design, and packaging), combination with agents targeting ET-related adverse events, and a mobile application to support them during ET. Of the 1103 individuals who started the survey, 939 (85.1%) were eligible for enrollment and completed the survey. The majority of the participants considered that a personalized ET should take into consideration the intake schedule (n = 974, 90.7%) and swallowable tablet formulation (n = 606, 64.5%), without a preference for ET presentation (n = 619; 65.9%). The majority of the participants expressed a willingness to participate in a potential clinical trial evaluating the combination of ET with agents targeting ET-related adverse events at the start of ET (n = 752, 80.1%) or in the case of major ET-related adverse events (n = 778, 82.8%). The primary considerations were to have an uncompromised ET efficacy and a guaranteed reduction of adverse events. Last, a dedicated mobile application was considered helpful by 665 participants (70.8%). Informative tools should focus on the recommendations for dealing with adverse events (n = 593, 63.2%), the impact on the patient's daily life (n = 515, 54.9%), benefits (n = 504, 53.7%), and adverse events (n = 494, 52.6%) of ET. This survey paves the way for multimodal strategies that can include a personalized ET (e.g., ET in combination with agents targeting ET-related adverse events) and dedicated mobile applications to ultimately improve adherence.

Understanding and Overcoming Resistance to Selective FGFR inhibitors Across FGFR2-Driven Malignancies.

PURPOSE: Understanding resistance to selective FGFR inhibitors is crucial to improve the clinical outcomes of patients with FGFR2-driven malignancies. EXPERIMENTAL DESIGN: We analyzed sequential ctDNA, +/- WES or targeted NGS on tissue biopsies from patients with tumors harboring activating FGFR2 alterations progressing on pan-FGFR-selective inhibitors, collected in the prospective UNLOCK program. FGFR2::BICC1 Ba/F3 and patient-derived xenografts (PDX) models were used for functional studies. RESULTS: Thirty-six patients were included. In cholangiocarcinoma, at resistance to both reversible inhibitors (e.g. pemigatinib, erdafitinib) and the irreversible inhibitor futibatinib, polyclonal FGFR2 kinase domain mutations were frequent (14/27 patients). Tumors other than cholangiocarcinoma shared the same mutated FGFR2 residues, but polyclonality was rare (1/9 patients). At resistance to reversible inhibitors, 14 residues in the FGFR2 kinase domain were mutated; after futibatinib, only the molecular brake N550 and the gatekeeper V565. Off-target alterations in PI3K/mTOR and MAPK pathways were found in 11 patients, often together with on-target mutations. At progression to a first FGFR inhibitor, 12 patients received futibatinib or lirafugratinib (irreversible inhibitors), with variable clinical outcomes depending on previous resistance mechanisms. Two patients with TSC1 or PIK3CA mutations benefitted from everolimus. In cell viability assays on Ba/F3 and in pharmacologic studies on PDX, irreversible inhibitors retained better activity against FGFR2 kinase domain mutations, with lirafugratinib active against the recalcitrant V565L/F/Y. CONCLUSIONS: At progression to FGFR inhibitors, FGFR2-driven malignancies are characterized by high intra- and inter-patient molecular heterogeneity, particularly in cholangiocarcinoma. Resistance to FGFR inhibitors can be overcome by sequential, molecularly-oriented treatment strategies across FGFR2-driven tumors.

Individualizing busulfan dose in specific populations and evaluating the risk of pharmacokinetic drug-drug interactions.

INTRODUCTION: Busulfan is an alkylating agent widely used in the conditioning of hematopoietic stem cell transplantation possessing a complex metabolism and a large interindividual and intra-individual variability, especially in children. Combined with the strong rationale of busulfan PK/PD relationships, factors altering its clearance (e.g. weight, age, and GST-A genetic polymorphism mainly) can also affect clinical outcomes. AREAS COVERED: This review aims to provide an overview of the current knowledge on busulfan pharmacokinetics, its pharmacokinetics variabilities in pediatric populations, drug-drug interactions (DDI), and their consequences regarding dose individualization. This review was based on medical literature up until October 2021. EXPERT OPINION: To ensure effective busulfan exposure in pediatrics, different weight-based nomograms have been established to determine busulfan dosage and provided improved results (65-80% of patients correctly exposed). In addition to nomograms, therapeutic drug monitoring (TDM) of busulfan measuring plasmatic concentrations to estimate busulfan pharmacokinetic parameters can be used. TDM is now widely carried out in routine practices and aims to ensure the targeting of the reported therapeutic windows by individualizing busulfan dosing based on the clearance estimations from a previous dose.

Resistance to Selective FGFR Inhibitors in FGFR-Driven Urothelial Cancer.

Several fibroblast growth factor receptor (FGFR) inhibitors are approved or in clinical development for the treatment of FGFR-driven urothelial cancer, and molecular mechanisms of resistance leading to patient relapses have not been fully explored. We identified 21 patients with FGFR-driven urothelial cancer treated with selective FGFR inhibitors and analyzed postprogression tissue and/or circulating tumor DNA (ctDNA). We detected single mutations in the FGFR tyrosine kinase domain in seven (33%) patients (FGFR3 N540K, V553L/M, V555L/M, E587Q; FGFR2 L551F) and multiple mutations in one (5%) case (FGFR3 N540K, V555L, and L608V). Using Ba/F3 cells, we defined their spectrum of resistance/sensitivity to multiple selective FGFR inhibitors. Eleven (52%) patients harbored alterations in the PI3K-mTOR pathway (n = 4 TSC1/2, n = 4 PIK3CA, n = 1 TSC1 and PIK3CA, n = 1 NF2, n = 1 PTEN). In patient-derived models, erdafitinib was synergistic with pictilisib in the presence of PIK3CA E545K, whereas erdafitinib-gefitinib combination was able to overcome bypass resistance mediated by EGFR activation. SIGNIFICANCE: In the largest study on the topic thus far, we detected a high frequency of FGFR kinase domain mutations responsible for resistance to FGFR inhibitors in urothelial cancer. Off-target resistance mechanisms involved primarily the PI3K-mTOR pathway. Our findings provide preclinical evidence sustaining combinatorial treatment strategies to overcome bypass resistance. See related commentary by Tripathi et al., p. 1964. This article is featured in Selected Articles from This Issue, p. 1949.

Population Pharmacokinetic Analysis of Pazopanib in Patients and Determination of Target AUC.

Pazopanib is a potent multi-targeted kinase inhibitor approved for the treatment of advanced renal cell carcinoma and soft tissue sarcoma. The pharmacokinetics of pazopanib is characterized by a significant inter- and intra-patient variability and a target through plasma concentration of 20.5 mg·L-1. However, routine monitoring of trough plasma concentrations at fixed hours is difficult in daily practice. Herein, we aimed to characterize the pharmacokinetic (PK) profile of pazopanib and to identify a target area under the curve (AUC) more easily extrapolated from blood samples obtained at various timings after drug intake. A population pharmacokinetic (popPK) model was constructed to analyze pazopanib PK and to estimate the pazopanib clearance of a patient regardless of the time of sampling. Data from the therapeutic drug monitoring (TDM) of patients with cancer at Institute Gustave Roussy and a clinical study (phase I/II) that evaluates the tolerance to pazopanib were used. From the individual clearance, it is then possible to obtain the patient's AUC. A target AUC for maximum efficacy and minimum side effects of 750 mg·h·L-1 was determined. The comparison of the estimated AUC with the target AUC would enable us to determine whether plasma exposure is adequate or whether it would be necessary to propose therapeutic adjustments.

Amniotic Aaquaporins (AQP) in Normal and Pathological Pregnancies: Interest in Polyhydramnios.

Polyhydramnios is a common feature diagnosed by ultrasound in the second half of pregnancy. Biochemical analysis of amniotic fluid can be useful when suspecting Bartter syndrome or digestive atresia but in most of cases, no etiology of polyhydramnios is found because of the complex regulation of amniotic fluid. Aquaporins (AQP) are transmembrane channel proteins contributing to water transfers. Some of them are expressed in fetal membranes and placenta. Their expression has been shown to be disrupted in some pathological conditions such as maternal diabetes, often associated with polyhydramnios. AQP-1, 3 and 8 levels in amniotic fluid were retrospectively measured in patients suffering from polyhydramnios (n=21) from 23 weeks of gestation (WG). They were compared to the levels observed in control subjects (n=96) and their relationship with maternal factors and neonatal issues was analyzed. AQP-1, 3, 8 levels were physiologically fluctuating, AQP-1 levels always being the lowest and AQP-3 the highest, with a significant decrease at the end of pregnancy. AQPs/AFP ratios increased about 8 folds during pregnancy, their kinetic profiles reflecting physiological dynamic evolution of amniotic fluid volume. In polyhydramnios, AQP-3 level tended to be decreased whereas AQP-8 level was decreased from mid-gestation whatever the etiology of polyhydramnios. No significant relationship was found between AQPs levels and either the fetal prematurity degree or macrosomia. No specific pattern was observed in idiopathic polyhydramnios, limiting the interest of AQPs dosage in amniotic fluid in the management of those complicated pregnancies.

Chronic Plasma Exposure to Kinase Inhibitors in Patients with Oncogene-Addicted Non-Small Cell Lung Cancer.

Kinase inhibitors (KI) have dramatically improved the outcome of treatment in patients with non-small cell lung cancer (NSCLC), which harbors an oncogene addiction. This study assesses KI plasma levels and their clinical relevance in patients chronically exposed to KIs. Plasma samples were collected in NSCLC patients receiving erlotinib, gefitinib, osimertinib, crizotinib, or dabrafenib (with or without trametinib) for at least three months between November 2013 and February 2019 in a single institution. KI drug concentrations were measured by ultra-performance liquid chromatography coupled with tandem mass spectrometry and compared to published data defining optimal plasma concentration. The main outcome was the rate of samples with suboptimal KI plasma concentrations. Secondary outcomes included its impact on T790M mutation emergence in patients receiving a first-generation epidermal growth factor receptor (EGFR) KI. Fifty-one samples were available from 41 patients with advanced NSCLC harboring driver genetic alterations, including EGFR, v-Raf murine sarcoma viral oncogene homolog B (BRAF), anaplastic lymphoma kinase (ALK) or ROS proto-oncogene 1 (ROS1), and who had an available evaluation of chronic KI plasma exposure. Suboptimal plasma concentrations were observed in 51% (26/51) of cases. In EGFR-mutant cases failing first-generation KIs, EGFR exon 20 p.T790M mutation emergence was detected in 31% (4/13) of samples in optimal vs. none in suboptimal concentration (0/5). Suboptimal plasma concentrations of KIs are frequent in advanced NSCLC patients treated with a KI for at least three months and might contribute to treatment failure.

Association of serum angiogenic factors with bronchopulmonary dysplasia. The ANGIODYS cohort study.

OBJECTIVES: Angiogenic factors may be involved in lung development. To evaluate the relations between maternal and cord blood angiogenic factors (sFlt-1, placental growth factor [PlGF], soluble endogline [sEng], transforming growth factor ß [TGF-beta]) and their association with moderate and severe bronchopulmonary dysplasia (BPD) in very preterm growth-restricted infants. STUDY DESIGN: Prospective monocentric cohort study. Twenty-four mother-child dyads featuring antepartum preeclampsia, intra-uterine growth restriction (IUGR) and birth before 30 weeks' gestation were included. This ensured a 80% power to test whether sFlt-1 maternal levels would be twice as high in cases of BPD as in the absence of BPD. MAIN OUTCOME MEASURES: Four pro/anti-angiogenic factors from two pathways (sFlt-1, PlGF and sEng, TGF-beta) were measured in maternal serum before delivery (at the time of hospitalization or the day of birth) and in neonates' cord blood. Neonatal outcome was moderate to severe BPD, defined as oxygen requirement for at least 28 days and persistent need for oxygen or ventilatory support at 36 weeks' postmenstrual age. RESULTS: sFlt-1 levels were positively correlated in maternal serum and cord blood (rs = 0.83, p < .001) but levels of PlGF and TGF-beta and its receptor sEng were not. Among all the factors studied in cord and maternal blood, none was associated with BPD. CONCLUSIONS: In IUGR preterm babies born before 30 weeks' gestation from preeclamptic mothers, serum sFlt-1, PlGF and sEng, TGF-ß levels were not correlated with BPD. The increased BPD risk in preterm neonates born from preeclamptic mothers cannot be related to high sFlt-1 levels.

Prevention of Invasive Aspergillus Fungal Infections with the Suspension and Delayed-Release Tablet Formulations of Posaconazole in Patients with Haematologic Malignancies.

Posaconazole is a triazole antifungal used to prevent invasive fungal infections (IFIs) in patients receiving chemotherapy or haemotopoietic stem cell transplantation. Due to highly variable bioavailability of the oral suspension formulation, a delayed-release tablet was developed which showed improved bioavailability. A minimal target posaconazole plasma concentration of 0.7 mg/L is recommended for prophylaxis of IFIs. However, the relationship between plasma concentration of posaconazole and its efficacy against IFIs remains unclear. We analysed trough posaconazole concentrations and response against IFIs in 50 and 104 patients with haematologic malignancies receiving prophylactic posaconazole as the tablet or suspension formulation, respectively. Mean plasma concentration of posaconazole was 1.91 ± 1.06 mg/L and 0.82 ± 0.57 mg/L in the tablet and the oral suspension group, respectively (p < 0.0001). The percentage of patients reaching the minimal target concentration of 0.7 mg/L was 92.0% and 47.1% in the tablet and oral suspension groups, respectively (p < 0.0001). Emergent aspergillosis occurred in 9 (8.7%) patients in the suspension group and in none of the patients taking the tablet formulation (p = 0.032). Our results show a relationship between plasma concentrations of posaconazole and its prophylactic efficacy in patients with haematologic malignancies. Target posaconazole concentrations are reached more efficiently with the tablet than with the suspension formulation.