Immunogenicity of standard and extended dosing intervals of BNT162b2 mRNA vaccine.

Extension of the interval between vaccine doses for the BNT162b2 mRNA vaccine was introduced in the United Kingdom to accelerate population coverage with a single dose. At this time, trial data were lacking, and we addressed this in a study of United Kingdom healthcare workers. The first vaccine dose induced protection from infection from the circulating alpha (B.1.1.7) variant over several weeks. In a substudy of 589 individuals, we show that this single dose induces severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibody (NAb) responses and a sustained B and T cell response to the spike protein. NAb levels were higher after the extended dosing interval (6-14 weeks) compared with the conventional 3- to 4-week regimen, accompanied by enrichment of CD4+ T cells expressing interleukin-2 (IL-2). Prior SARS-CoV-2 infection amplified and accelerated the response. These data on dynamic cellular and humoral responses indicate that extension of the dosing interval is an effective immunogenic protocol.

Testing fractional doses of COVID-19 vaccines.

Due to the enormous economic, health, and social costs of the COVID-19 pandemic, there are high expected social returns to investing in parallel in multiple approaches to accelerating vaccination. We argue there are high expected social returns to investigating the scope for lowering the dosage of some COVID-19 vaccines. While existing evidence is not dispositive, available clinical data on the immunogenicity of lower doses combined with evidence of a high correlation between neutralizing antibody response and vaccine efficacy suggests that half or even quarter doses of some vaccines could generate high levels of protection, particularly against severe disease and death, while potentially expanding supply by 450 million to 1.55 billion doses per month, based on supply projections for 2021. An epidemiological model suggests that, even if fractional doses are less effective than standard doses, vaccinating more people faster could substantially reduce total infections and deaths. The costs of further testing alternative doses are much lower than the expected public health and economic benefits. However, commercial incentives to generate evidence on fractional dosing are weak, suggesting that testing may not occur without public investment. Governments could support either experimental or observational evaluations of fractional dosing, for either primary or booster shots. Discussions with researchers and government officials in multiple countries where vaccines are scarce suggests strong interest in these approaches.

Efficacy and safety of rademikibart (CBP-201), a next-generation mAb targeting IL-4Rα, in adults with moderate to severe atopic dermatitis: A phase 2 randomized trial (CBP-201-WW001).

BACKGROUND: Rademikibart (CBP-201) is a next-generation IL-4 receptor alpha-targeting antibody. OBJECTIVE: We sought to evaluate rademikibart in adults with moderate to severe atopic dermatitis. METHODS: A total of 226 patients were randomized, double-blind, to subcutaneous rademikibart (300 mg every 2 weeks [Q2W], 150 mg Q2W, 300 mg every 4 weeks [Q4W]; plus 600-mg loading dose) or placebo. Randomization began in July 2020. The trial was completed in October 2021. RESULTS: The WW001 phase 2 trial achieved its primary end point: significant percent reduction from baseline in least-squares mean Eczema Area Severity Index (EASI) to week 16 with rademikibart 300 mg Q2W (-63.0%; P = .0007), 150 mg Q2W (-57.6%; P = .0067), 300 mg Q4W (-63.5%; P = .0004) versus placebo (-39.7%). EASI scores decreased significantly with 300 mg Q2W and Q4W at the earliest assessment (week 2), with no evidence of plateauing by week 16. Significant improvements were also observed in secondary end points, including pruritus. Across the primary and secondary end points, efficacy tended to be comparable with 300 mg Q2W and Q4W dosing. Rademikibart and placebo had similar, low incidence of treatment-emergent adverse events (TEAEs) (48% vs 54%), serious TEAEs (1.8% vs 3.6%), TEAEs leading to treatment discontinuation (1.2% vs 1.8%), conjunctivitis of unspecified cause (2.9% vs 0%), herpes (0.6% vs 1.8%), and injection-site reactions (1.8% vs 1.8%). Although no discontinuations were attributed to coronavirus disease 2019, pandemic-related restrictions likely had an impact on trial conduct. CONCLUSIONS: Rademikibart was efficacious and well tolerated at Q2W and Q4W intervals. Q4W dosing is a more convenient frequency than approved for current therapies.

Pharmacokinetic-Pharmacodynamic Evidence From a Phase 3 Trial to Support Flat-Dosing of Rifampicin for Tuberculosis.

BACKGROUND: The optimal dosing strategy for rifampicin in treating drug-susceptible tuberculosis (TB) is still highly debated. In the phase 3 clinical trial Study 31/ACTG 5349 (NCT02410772), all participants in the control regimen arm received 600 mg rifampicin daily as a flat dose. Here, we evaluated relationships between rifampicin exposure and efficacy and safety outcomes. METHODS: We analyzed rifampicin concentration time profiles using population nonlinear mixed-effects models. We compared simulated rifampicin exposure from flat- and weight-banded dosing. We evaluated the effect of rifampicin exposure on stable culture conversion at 6 months; TB-related unfavorable outcomes at 9, 12, and 18 months using Cox proportional hazard models; and all trial-defined safety outcomes using logistic regression. RESULTS: Our model-derived rifampicin exposure ranged from 4.57 mg · h/L to 140.0 mg · h/L with a median of 41.8 mg · h/L. Pharmacokinetic simulations demonstrated that flat-dosed rifampicin provided exposure coverage similar to the weight-banded dose. Exposure-efficacy analysis (n = 680) showed that participants with rifampicin exposure below the median experienced similar hazards of stable culture conversion and TB-related unfavorable outcomes compared with those with exposure above the median. Exposure-safety analysis (n = 722) showed that increased rifampicin exposure was not associated with increased grade 3 or higher adverse events or serious adverse events. CONCLUSIONS: Flat-dosing of rifampicin at 600 mg daily may be a reasonable alternative to the incumbent weight-banded dosing strategy for the standard-of-care 6-month regimen. Future research should assess the optimal dosing strategy for rifampicin, at doses higher than the current recommendation.

Comprehensive Review on the Use of Oral Cholera Vaccine (OCV) in Ethiopia: 2019 to 2023.

BACKGROUND: Cholera outbreaks in Ethiopia necessitate frequent mass oral cholera vaccine (OCV) campaigns. Despite this, there is a notable absence of a comprehensive summary of these campaigns. Understanding national OCV vaccination history is essential to design appropriate and effective cholera control strategies. Here, we aimed to retrospectively review all OCV vaccination campaigns conducted across Ethiopia between 2019 and 2023. METHODS: The OCV request records from 2019 to October 2023 and vaccination campaign reports for the period from 2019 to December 2023 were retrospectively accessed from the Ethiopia Public Health Institute (EPHI) database. Descriptive analysis was conducted using the retrospective data collected. RESULTS: From 2019 to October 2023, Ethiopian government requested 32 044 576 OCV doses (31 899 576 doses to global stockpile; 145 000 doses to outside of stockpile). Around 66.3% of requested doses were approved; of which 90.4% were received. Fifteen OCV campaigns (12 reactive and 3 pre-emptive) were conducted, including five two-dose campaigns with varying dose intervals and single-dose campaigns partially in 2019 and entirely in 2021, 2022 and 2023. Overall vaccine administrative coverage was high; except for Tigray region (41.8% in the 1st round; 2nd round didn't occur). The vaccine administrative coverage records were documented, but no OCV coverage survey data was available. CONCLUSIONS: This study represents the first comprehensive review of OCV campaigns in Ethiopia spanning the last five years. Its findings offer valuable insights into informing future cholera control strategies, underscoring the importance of monitoring and evaluation despite resource constraints. Addressing the limitations in coverage survey data availability is crucial for enhancing the efficacy of future campaigns.

Reporting on patient's body mass index (BMI) in recent clinical trials for patients with breast cancer: a systematic review.

BACKGROUND: The proportion of patients with breast cancer and obesity is increasing. While the therapeutic landscape of breast cancer has been expanding, we lack knowledge about the potential differential efficacy of most drugs according to the body mass index (BMI). Here, we conducted a systematic review on recent clinical drug trials to document the dosing regimen of recent drugs, the reporting of BMI and the possible exclusion of patients according to BMI, other adiposity measurements and/or diabetes (leading comorbidity of obesity). We further explored whether treatment efficacy was evaluated according to BMI. METHODS: A search of Pubmed and ClinicalTrials.gov was performed to identify phase I-IV trials investigating novel systemic breast cancer treatments. Dosing regimens and exclusion based on BMI, adiposity measurements or diabetes, documentation of BMI and subgroup analyses according to BMI were assessed. RESULTS: 495 trials evaluating 26 different drugs were included. Most of the drugs (21/26, 81%) were given in a fixed dose independent of patient weight. BMI was an exclusion criterion in 3 out of 495 trials. Patients with diabetes, the leading comorbidity of obesity, were excluded in 67/495 trials (13.5%). Distribution of patients according to BMI was mentioned in 8% of the manuscripts, subgroup analysis was performed in 2 trials. No other measures of adiposity/body composition were mentioned in any of the trials. Retrospective analyses on the impact of BMI were performed in 6 trials. CONCLUSIONS: Patient adiposity is hardly considered as most novel drug treatments are given in a fixed dose. BMI is generally not reported in recent trials and few secondary analyses are performed. Given the prevalence of patients with obesity and the impact obesity can have on pharmacokinetics and cancer biology, more attention should be given by investigators and study sponsors to reporting patient's BMI and evaluating its impact on treatment efficacy and toxicity.

Model-Informed Precision Dosing: Background, Requirements, Validation, Implementation, and Forward Trajectory of Individualizing Drug Therapy.

Model-informed precision dosing (MIPD) has become synonymous with modern approaches for individualizing drug therapy, in which the characteristics of each patient are considered as opposed to applying a one-size-fits-all alternative. This review provides a brief account of the current knowledge, practices, and opinions on MIPD while defining an achievable vision for MIPD in clinical care based on available evidence. We begin with a historical perspective on variability in dose requirements and then discuss technical aspects of MIPD, including the need for clinical decision support tools, practical validation, and implementation of MIPD in health care. We also discuss novel ways to characterize patient variability beyond the common perceptions of genetic control. Finally, we address current debates on MIPD from the perspectives of the new drug development, health economics, and drug regulations.

Alterations in the innate and adaptive immune system in a real-world cohort of multiple sclerosis patients treated with ocrelizumab.

B cell depletion by the anti-CD20 antibody ocrelizumab is effective in relapsing-remitting (RR) and primary progressive (PP) multiple sclerosis (MS). We investigated immunological changes in peripheral blood of a real-world MS cohort after 6 and 12 months of ocrelizumab. All RRMS and most PPMS patients (15/20) showed treatment response. Ocrelizumab not only reduced CD20+ B cells, but also numbers of CD20+ T cells. Absolute numbers of monocytes, dendritic cells and CD8+ T cells were increased, while CD56hi natural killer cells were reduced after ocrelizumab. The residual B cell population shifted towards transitional and activated, IgA+ switched memory B cells, double negative B cells, and antibody-secreting cells. Delaying the treatment interval by 2-3 months increased mean B cell frequencies and enhanced naive B cell repopulation. Ocrelizumab reduced plasma levels of interleukin(IL)-12p70 and interferon(IFN)-α2. These findings will contribute to understanding ineffective treatment responses, dealing with life-threatening infections and further unravelling MS pathogenesis.

Updated antimicrobial dosing recommendations for obese patients.

The prevalence of obesity has increased considerably in the last few decades. Pathophysiological changes in obese patients lead to pharmacokinetic (PK) and pharmacodynamic (PD) alterations that can condition the correct exposure to antimicrobials if standard dosages are used. Inadequate dosing in obese patients can lead to toxicity or therapeutic failure. In recent years, additional antimicrobial PK/PD data, extended infusion strategies, and studies in critically ill patients have made it possible to obtain data to provide a better dosage in obese patients. Despite this, it is usually difficult to find information on drug dosing in this population, which is sometimes contradictory. This is a comprehensive review of the dosing of different types of antimicrobials (antibiotics, antifungals, antivirals, and antituberculosis drugs) in obese patients, where the literature on PK and possible dosing strategies in obese adults was critically assessed.

Prospective validation of a model-informed precision dosing tool for vancomycin treatment in neonates.

We recruited 48 neonates (50 vancomycin treatment episodes) in a prospective study to validate a model-informed precision dosing (MIPD) software. The initial vancomycin dose was based on a population pharmacokinetic model and adjusted every 36-48 h. Compared with a historical control group of 53 neonates (65 episodes), the achievement of a target trough concentration of 10-15 mg/L improved from 37% in the study to 62% in the MIPD group (P = 0.01), with no difference in side effects.

Pulsed dosing and extended daily dosing of oral vancomycin do not facilitate clearance of Clostridioides difficile colonization in mice.

Vancomycin taper and pulse regimens are commonly used to treat recurrent Clostridioides difficile infections, but the mechanism by which these regimens might reduce recurrences is unclear. Here, we used a mouse model to test the hypothesis that pulse dosing of vancomycin after a 10-day treatment course enhances clearance of C. difficile from the intestinal tract. Mice with C. difficile colonization received 10 days of once-daily oral vancomycin followed by 20 days of treatment with saline (controls), daily vancomycin, or pulse dosing of vancomycin every 2 or 3 days. Stool samples were collected to measure the concentration of C. difficile during and after treatment, vancomycin concentrations, and growth of vegetative C. difficile during every 3 days dosing. Pulse dosing of vancomycin was not effective in maintaining suppression of C. difficile (P > 0.05 in comparison to saline controls); growth of vegetative C. difficile occurred between pulse doses when vancomycin decreased to undetectable levels. Daily dosing of vancomycin suppressed C. difficile during treatment, but recurrent colonization occurred after treatment in more than 75% of mice, and by post-treatment day 14, there was no significant difference among the control, pulse dosing, and daily dosing groups (P > 0.05). These findings demonstrate that pulse dosing of vancomycin every 2 or 3 days does not facilitate the clearance of C. difficile spores in mice. Studies are needed to examine the impact of vancomycin taper and pulsed regimens in patients.

Serum ganciclovir drug exposure in children receiving standard ganciclovir dosing.

Intravenous ganciclovir (GCV) is used for the treatment of cytomegalovirus (CMV) infection in immunocompromised children. Although the therapeutic target for treatment is unclear, studies have shown a serum area under the concentration-time curve (AUC24h) ≥40 mg/L·h correlates with effective CMV prevention. This study aimed to externally validate existing GCV population pharmacokinetic (PopPK) models and develop a model if needed and evaluate the serum AUC24h achieved with standard GCV dosing and propose an optimized dosing strategy for immunocompromised children. Ganciclovir drug monitoring data from two pediatric hospitals were retrospectively collected, and published pediatric PopPK models were externally validated. The population AUC24h with standard GCV dosing (5 mg/kg twice daily) was calculated, and an optimized dosing strategy was determined using Monte Carlo simulations to achieve an AUC24h between 40 and 100 mg/L·h. Overall, 161 samples from 23 children with a median (range) age of 9.0 years (0.4-17.0) and weight of 28.2 kg (5.6-73.3) were analyzed. Transferability of published pediatric PopPK models was limited. Thus, a one-compartment model with first-order absorption and elimination with weight and serum creatinine as covariates was developed. The median (5th-95th percentiles) steady state AUC24h with standard dosing was 38.3 mg/L·h (24.8-329.2) with 13 children having an AUC24h <40 mg/L·h, particularly those aged <4 years (8/13). An optimized simulated GCV dosing regimen, ranging from 2 to 13 mg/kg twice daily for children with normal renal function, achieved 61%-78% probability of target attainment. Standard GCV dosing likely results in inadequate drug exposure in more than half of the children, particularly those aged <4 years. An optimized dosing regimen has been proposed for clinical validation.

A machine learning approach to predict daptomycin exposure from two concentrations based on Monte Carlo simulations.

Daptomycin is a concentration-dependent lipopeptide antibiotic for which exposure/effect relationships have been shown. Machine learning (ML) algorithms, developed to predict the individual exposure to drugs, have shown very good performances in comparison to maximum a posteriori Bayesian estimation (MAP-BE). The aim of this work was to predict the area under the blood concentration curve (AUC) of daptomycin from two samples and a few covariates using XGBoost ML algorithm trained on Monte Carlo simulations. Five thousand one hundred fifty patients were simulated from two literature population pharmacokinetics models. Data from the first model were split into a training set (75%) and a testing set (25%). Four ML algorithms were built to learn AUC based on daptomycin blood concentration samples at pre-dose and 1 h post-dose. The XGBoost model (best ML algorithm) with the lowest root mean square error (RMSE) in a 10-fold cross-validation experiment was evaluated in both the test set and the simulations from the second population pharmacokinetic model (validation). The ML model based on the two concentrations, the differences between these concentrations, and five other covariates (sex, weight, daptomycin dose, creatinine clearance, and body temperature) yielded very good AUC estimation in the test (relative bias/RMSE = 0.43/7.69%) and validation sets (relative bias/RMSE = 4.61/6.63%). The XGBoost ML model developed allowed accurate estimation of daptomycin AUC using C0, C1h, and a few covariates and could be used for exposure estimation and dose adjustment. This ML approach can facilitate the conduct of future therapeutic drug monitoring (TDM) studies.

Population pharmacokinetic rationale for intravenous contezolid acefosamil followed by oral contezolid dosage regimens.

Contezolid is a novel oxazolidinone antibiotic with a promising safety profile. Oral contezolid and its intravenous (IV) prodrug contezolid acefosamil (CZA) are in development for treatment of diabetic foot and acute bacterial skin and skin structure infections (ABSSSI). The prodrug CZA is converted to active contezolid via intermediate MRX-1352. This study aimed to provide the pharmacokinetic rationale for safe, effective, and flexible dosage regimens with initial IV CZA followed by oral contezolid. We simultaneously modeled plasma concentrations from 110 healthy volunteers and 74 phase 2 patients with ABSSSI via population pharmacokinetics (using the importance sampling estimation algorithm), and optimized dosage regimens by Monte Carlo simulations. This included data on MRX-1352, contezolid, and its metabolite MRX-1320 from 66 healthy volunteers receiving intravenous CZA (150-2400 mg) for up to 28 days, and 74 patients receiving oral contezolid [800 mg every 12 h (q12h)] for 10 days. The apparent total clearance for 800 mg oral contezolid with food was 16.0 L/h (23.4% coefficient of variation) in healthy volunteers and 17.7 L/h (53.8%) in patients. CZA was rapidly converted to MRX-1352, which subsequently transformed to contezolid. The proposed dosage regimen used an IV CZA 2000 mg loading dose with 1000 mg IV CZA q12h as maintenance dose(s), followed by 800 mg oral contezolid q12h (with food). During each 24-h period, Monte Carlo simulations predicted this regimen to achieve consistent areas under the curve of 91.9 mg·h/L (range: 76.3-106 mg·h/L) under all scenarios. Thus, this regimen was predicted to reliably achieve efficacious contezolid exposures independent of timing of switch from IV CZA to oral contezolid.IMPORTANCEThis study provides the population pharmacokinetic rationale for the dosage regimen of the intravenous (IV) prodrug contezolid acefosamil (CZA) followed by oral contezolid. We developed the first integrated population model for the pharmacokinetics of the MRX-1352 intermediate prodrug, active contezolid, and its main metabolite MRX-1320 based on data from three clinical studies in healthy volunteers and phase 2 patients. The proposed regimen was predicted to reliably achieve efficacious contezolid exposures independent of timing of switch from IV CZA to oral contezolid.

Assessment of efficacy and safety of dose-dense doxorubicin and cyclophosphamide (ddAC) in combination with immunotherapy in early-stage triple-negative breast cancer.

PURPOSE: This study aimed to assess safety and efficacy of a modified KEYNOTE 522 protocol, which incorporated pembrolizumab every 6 weeks, allowing for concomitant dose-dense (14 day) doxorubicin and cyclophosphamide (ddAC). By optimizing this dosing, the intention of this modified protocol was to improve pathologic complete response (pCR) rates in a population associated with a poorer prognosis. METHODS: This was a retrospective, single-center, cohort study. Patients were included if they had early stage, triple-negative breast cancer, and received at least one dose of AC. The entire cohort received neoadjuvant chemotherapy including weekly carboplatin and paclitaxel with pembrolizumab every 3 weeks for 12 weeks (4 cycles). The group then received either ddAC with pembrolizumab 400 mg every 6 weeks, or AC with pembrolizumab 200 mg every 3 weeks. The primary objective was pCR rate at time of surgery. RESULTS: This study assessed outcomes in 25 patients over 34 months. The pCR rate in the pembrolizumab, AC 3-week cohort was 64.3% versus 81.8% in the ddAC and 6-week pembrolizumab group. No pembrolizumab-associated grade 3-4 adverse events occurred in the either cohort. Despite seeing an increased incidence of grade 3-4 toxicities in the ddAC arm, this did not result in additional chemotherapy delays or dose reductions. CONCLUSION: This study demonstrated tolerability and a potential for favorable outcomes with this patient population, making this modified KEYNOTE 522 protocol a reasonable treatment approach. Larger, prospective studies are warranted to assess the feasibility of this dosing and true optimization of patient outcomes given the small sample size of this study.

Evaluating the impact of extended dosing intervals on mRNA COVID-19 vaccine effectiveness in adolescents.

BACKGROUND: Extending the dosing interval of a primary series of mRNA COVID-19 vaccination has been employed to reduce myocarditis risk in adolescents, but previous evaluation of impact on vaccine effectiveness (VE) is limited to risk after second dose. METHODS: We quantified the impact of the dosing interval based on case notifications and vaccination uptake in Hong Kong from January to April 2022, based on calendar-time proportional hazards models and matching approaches. RESULTS: We estimated that the hazard ratio (HR) and odds ratio (OR) of infections after the second dose for extended (28 days or more) versus regular (21-27 days) dosing intervals ranged from 0.86 to 0.99 from calendar-time proportional hazards models, and from 0.85 to 0.87 from matching approaches, respectively. Adolescents in the extended dosing groups (including those who did not receive a second dose in the study period) had a higher hazard of infection than those with a regular dosing interval during the intra-dose period (HR 1.66; 95% CI 1.07, 2.59; p = 0.02) after the first dose. CONCLUSIONS: Implementing an extended dosing interval should consider multiple factors including the degree of myocarditis risk, the degree of protection afforded by each dose, and the extra protection achievable using an extended dosing interval.

Correlation between Metabolic Parameters and Warfarin Dose in Patients with Heart Valve Replacement of Different Genotypes.

Background: Warfarin has become the first choice for anticoagulation in patients who need lifelong anticoagulation due to its clinical efficacy and low price. However, the anticoagulant effect of warfarin is affected by many drugs, foods, etc. accompanied by a high risk of bleeding and embolism. The Vitamin K epoxide reductase complex 1 (VKORC1) and Cytochrome P450 2C9 (CYP2C9) genotypic variation can influence the therapeutic dose of warfarin. However, it is not clear whether there is a correlation between warfarin dose and liver function, kidney function and metabolic markers such as uric acid (UA) in patients with different genotypes. We performed a single-center retrospective cohort study to evaluate the factors affecting warfarin dose and to establish a dose conversion model for warfarin patients undergoing heart valve replacement. Methods: We studied 343 patients with a mechanical heart valve replacement, compared the doses of warfarin in patients with different warfarin-related genotypes (CYP2C9 and VKORC1), and analyzed the correlation between liver function, kidney function, UA and other metabolic markers and warfarin dose in patients with different genotypes following heart valve replacement. Results: Genotype analysis showed that 72.01% of patients had CYP2C9*1/*1 and VKORC1 mutant AA genotypes. Univariate regression analysis revealed that the warfarin maintenance dose was significantly correlated with gender, age, body surface area (BSA), UA and genotype. There was no correlation with liver or kidney function. Multiple linear regression analysis showed that BSA, genotype and UA were the independent factors influencing warfarin dose. Conclusions: There is a significant correlation between UA content and warfarin dose in patients with heart valve replacement genotypes CYP2C9*1/*1/VKORC1(GA+GG), CYP2C9*1/*1/VKORC1AA and CYP2C9*1/*1/VKORC1AA.

High-dose individualized antithymocyte globulin with therapeutic drug monitoring in high-risk cord blood transplant.

BACKGROUND: Graft-versus-host disease (GvHD) and rejection are main limitations of cord blood transplantation (CBT), more so in patients with severe inflammation or previous rejections. While rigorous T-cell depletion with antithymocyte globulin (ATG) is needed to prevent GvHD and rejection, overexposure to ATG leads to slow T-cell recovery after transplantation, especially in CBT. OBJECTIVE: To evaluate high-dose, upfront ATG with individualized dosing and therapeutic drug monitoring (TDM) in pediatric CBT for patients at high risk for GvHD and rejection. STUDY DESIGN: Heavily inflamed patients and patients with a recent history of rejection were eligible for individualized high-dose ATG with real-time TDM. The ATG dosing scheme was adjusted to target a post-CBT exposure of <10 AU*day/mL, while achieving a pre-CBT exposure of 60-120 AU*day/mL; exposure levels previously defined for optimal efficacy and safety in terms of reduced GvHD and rejection, respectively. Main outcomes of interest included efficacy (target exposure attainment) and safety (incidence of GvHD and rejection). Other outcomes of interest included T-cell recovery and survival. RESULTS: Twenty-one patients were included ranging from 2 months to 18 years old, receiving an actual median cumulative dose of ATG of 13.3 mg/kg (range 6-30 mg/kg) starting at a median 15 days (range 12-17) prior to CBT. Dosing was adjusted in 14 patients (increased in 3 and decreased in 11 patients). Eighteen (86%) and 19 (91%) patients reached the target pre-CBT and post-CBT exposure, respectively. Cumulative incidence for acute GvHD was 34% (95% CI 23-45) and 5% (95% CI 0-10%) for grade 2-4 and grade 3-4, respectively; cumulative incidence of rejection was 9% (95% CI 2-16%). Overall survival was 75% (95% CI 65-85%). CONCLUSION: Individualized high-dose ATG with TDM is feasible and safe for patients with hyperinflammation in a CBT setting. We observe high target ATG exposure attainment, good immune reconstitution (despite very high doses of ATG) and acceptable rates of GvHD and rejection.

Impact of rabbit anti-thymocyte globulin (ATG) exposure on outcomes after ex vivo T-cell-depleted hematopoietic cell transplantation in pediatric and young adult patients.

BACKGROUND AIMS: Traditional weight-based dosing of rabbit anti-thymocyte globulin (rATG) used in allogeneic hematopoietic cell transplantation (HCT) to prevent graft-versus-host disease (GVHD) and graft rejection leads to variable exposures. High exposures induce delayed CD4+immune reconstitution (CD4+IR) and greater mortality. We sought to determine the impact of rATG exposure in children and young adults receiving various types of EX-VIVO T-cell-depleted (EX-VIVO-TCD) HCT. METHODS: Patients receiving their first EX-VIVO-TCD HCT (CliniMACS CD34+, Isolex or soybean lectin agglutination), with removal of residual T cells by E-rosette depletion (E-) between 2008 and 2018 at Memorial Sloan Kettering Cancer Center were retrospectively analyzed. rATG exposure post-HCT was estimated (AU*d/L) using a validated population pharmacokinetic model. Previously defined rATG-exposures, <30, 30-55, ≥55 AU*d/L, were related with outcomes of interest. Cox proportional hazard and cause-specific models were used for analyses. RESULTS: In total, 180 patients (median age 11 years; range 0.1-44 years) were included, malignant 124 (69%) and nonmalignant 56 (31%). Median post-HCT rATG exposure was 32 (0-104) AU*d/L. Exposure <30 AU*d/L was associated with a 3-fold greater probability of CD4+IR (P < 0.001); 2- to 4-fold lower risk of death (P = 0.002); and 3- to 4-fold lower risk of non-relapse mortality (NRM) (P = 0.02). Cumulative incidence of NRM was 8-fold lower in patients who attained CD4+IR compared with those who did not (P < 0.0001). There was no relation between rATG exposure and aGVHD (P = 0.33) or relapse (P = 0.23). Effect of rATG exposure on outcomes was similar in three EX-VIVO-TCD methods. CONCLUSIONS: Individualizing rATG dosing to target a low rATG exposure post-HCT while maintaining total cumulative exposure may better predict CD4+IR, reduce NRM and increase overall survival, independent of the EX-VIVO-TCD method.

Real-world dosing of regorafenib and outcomes among patients with metastatic colorectal cancer: a retrospective analysis using US claims data.

BACKGROUND: The randomized, dose-optimization, open-label ReDOS study in US patients with metastatic colorectal cancer (CRC) showed that, compared with a standard dosing approach, initiating regorafenib at 80 mg/day and escalating to 160 mg/day depending on tolerability increased the proportion of patients reaching their third treatment cycle and reduced the incidence of adverse events without compromising efficacy. Subsequently, the ReDOS dose-escalation strategy was included as an alternative regorafenib dosing option in the National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines. A retrospective analysis was conducted using a US claims database to assess whether inclusion of this dose-escalation strategy in NCCN Guidelines has influenced the use of flexible dosing in routine US clinical practice, and to describe clinical outcomes pre- and post-inclusion in NCCN Guidelines. METHODS: Patients with CRC in the Optum's de-identified Clinformatics® Data Mart database initiating regorafenib for the first time between January 2016 and June 2020 were stratified based on whether they initiated regorafenib pre- or post-inclusion of ReDOS in NCCN Guidelines, and in two groups: flexible dosing (< 160 mg/day; < 84 tablets in the first treatment cycle) and standard dosing (160 mg/day; ≥ 84 tablets in the first treatment cycle). The primary endpoints were the proportion of patients who initiated their third treatment cycle and the mean number of treatment cycles per group. RESULTS: 703 patients initiated regorafenib during the study period, of whom 310 (44%) initiated before and 393 (56%) initiated after inclusion of ReDOS in NCCN Guidelines. After inclusion in the guidelines, the proportion of patients who received flexible dosing increased from 21% (n = 66/310) to 45% (n = 178/393), the proportion who received standard dosing decreased from 79% (n = 244/310) to 55% (n = 215/393), the proportion who initiated their third treatment cycle increased from 36% (n = 113/310) to 46% (n = 179/393), and the mean (standard deviation) number of treatment cycles increased from 2.6 (2.9) to 3.2 (3.1). CONCLUSIONS: Following inclusion of ReDOS in NCCN Guidelines, real-world data suggest that US clinicians have markedly increased use of flexible dosing in clinical practice, potentially maximizing clinical benefits and safety outcomes for patients with metastatic CRC receiving regorafenib.