Replacing serum with dried blood microsampling for pharmacokinetics, viral neutralisation and immunogenicity bioanalysis supporting future paediatric development of RSM01, a candidate respiratory syncytial virus neutralising monoclonal antibody

BACKGROUND

Virus neutralising antibodies in serum are considered key correlates of protection for vaccines and monoclonal antibodies against respiratory syncytial virus (RSV). RSM01 is a novel, highly-potent, half-life-extended and fully-human monoclonal antibody candidate targeting the RSV prefusion F protein. Currently in Phase 1 development, RSM01 is primarily being developed to potentially provide an effective and affordable RSV prevention strategy in low- and middle-income countries. To evaluate the ability of dried blood collection to generate data sets and conclusions comparable to serum collection, we compared pharmacokinetics (PK) of RSM01, immunogenicity, and virus neutralisation for dried capillary blood samples with serum samples.

METHODS

RSM01 PK, anti-drug antibodies (ADA), and RSV-neutralising antibodies from the Phase 1 trial were analyzed and compared between matched serum and dried blood samples. Deming regression analysis was performed using baseline-corrected values to evaluate correlation between measurements in liquid serum versus dried blood.

RESULTS

The analysis showed good correlation (R2 > 0.95) between individual RSM01 concentrations measured in both serum and capillary blood. Analysis of RSM01 PK parameters in capillary blood yielded equivalent conclusions as from serum. A strong correlation (R2 > 0.95) was observed between RSV neutralising activity measured in both serum and capillary blood. In addition, RSV neutralising activity was correlated with RSM01 concentrations in both serum and capillary blood data sets. For ADA, individual sample results had 96% agreement (290/302) and overall participant ADA status had 93% agreement (52/56).

CONCLUSIONS

Both RSM01 concentrations and RSV neutralising activity showed a strong correlation between the serum and blood measurements. ADA measurements also had an agreement of > 90% for individual samples and overall participant status. Our results demonstrate that dried blood is a suitable specimen type for collection and evaluation in the RSM01 clinical development program and shows promise as a useful approach to reduce patient burden in clinical trials, particularly for infants in low- and middle-income countries.

TRIAL REGISTRATION

Clinicaltrials.gov NCT05118386 November 12, 2021.

Dried Blood Spot Sampling for Monitoring Children With Immune-Mediated Glomerulopathies and After Kidney Transplantation

Introduction

Monitoring kidney function and immunosuppressant levels in children post-kidney transplantation or those with glomerulopathies is challenging due to frequent venipunctures and clinic visits. Capillary dried blood spot sampling (DBS) offers a potential alternative.

Methods

In this prospective single-center study, 89 children (38% female and 62% male) requiring therapeutic drug monitoring (TDM) and kidney function assessment were enrolled. Of the patients, 79% were kidney transplant recipients, and 21% had immune-mediated glomerulopathies. The mean age was 13.4 (range, 5.7-18.0) years. DBS and standard venous serum samples were collected simultaneously for tacrolimus (TAC), cyclosporine A (CsA), everolimus (EVR), and creatinine levels. Furthermore, patient feedback on pain perception and feasibility was collected via questionnaire.

Results

No significant differences in parameter values between DBS and standard methods were observed (creatinine, -1.7 ± 14.5 μmol/l; EVR, 0.1 ± 1.2 μg/l; TAC, 0.3 ± 1.1 μg/l; CsA, 2.8 ± 9.8 μg/l). DBS demonstrated sufficient accuracy compared with standard methods. Patients favored DBS and telehealth consultations, especially due to less travel and school absences. Patients preferred finger pricking over ear pricking.

Conclusion

Capillary DBS proves reliable for TDM and kidney function assessment in pediatric kidney disease. It reduces patient and family burden compared with venous blood collection and enables telehealth consultations.

Challenges and Opportunities with at-Home Blood Collection for HIV-1 Viral Load Monitoring among Sexual Minoritized Men who use Stimulants

Sexually minoritized men (SMM) with HIV who use stimulants experience difficulties achieving and maintaining an undetectable viral load (VL). Home-based VL monitoring could augment HIV care by supporting interim, early identification of detectable VL. We describe implementation challenges associated with a home-collection device for laboratory-based VL testing among SMM with HIV who use stimulants. From March-May 2022, cisgender SMM with HIV reporting moderate-to-severe stimulant use disorder and suboptimal (< 90%) past-month antiretroviral therapy (ART) adherence were recruited via a consent-to-contact participant registry. Eligible men completed teleconference-based informed consent and were mailed a HemaSpot-HD blood collection device (volume capacity 160 µL; lower limit of detection 839 copies/mL) with detailed instructions for home blood self-collection and return shipment. Implementation process measures included estimated blood volume and VL quantification. Among 24 participants, 21 (88%) returned specimens with a median duration of 23 days (range: 10-71 days) between sending devices to participants and receiving specimens. Of these, 13/21 (62%) included enough blood (≥ 40 µL) for confidence in detectable/undetectable results; 10/13 (77%) had detectable VL, with 4/10 (40%) were quantifiable at ≥ 839 copies/mL. The remaining 8/21 had low blood volume (< 40 µL), but 3/8 (38%) still had detectable VL, with 1/3 (33%) quantifiable at ≥ 839 copies/mL. Home blood collection of ≥ 40 µL using HemaSpot-HD was feasible among this high-priority population, with > 50% having a VL detected. However, interim VL monitoring using HemaSpot-HD among those experiencing difficulties with ART adherence may be strengthened by building rapport via teleconferencing and providing detailed instructions to achieve adequate sample volume.

Validation and Clinical Application of a Liquid Chromatography-Ultraviolet Detection Method to Quantify Dolutegravir in Dried Blood Spots

BACKGROUND

Dolutegravir is currently the preferred component of first-line antiretroviral therapy. To facilitate clinical pharmacology studies in key populations, quantitative analytical methods compatible with microsampling and adaptable to resource-limited settings are desirable. The authors developed and validated a liquid chromatography-ultraviolet detection method to quantify dolutegravir in dried blood spots (DBS).

METHODS

Calibration standards and quality control samples were prepared by spotting 50 μL of dolutegravir-spiked whole blood on each circle of DBS cards. Three spots (two 6-mm punches/spot) were extracted with methanol. Chromatographic separation was achieved with gradient elution of acetonitrile/potassium phosphate monobasic buffer (pH 5) on a reverse-phase C18 column (flow rate, 1 mL/min) using pioglitazone as the internal standard. UV detection was performed at 260 nm. In the clinical pharmacokinetic study, DBS from finger prick was collected from participants (n = 10) at 8 time points over 12 hours postdosing, with paired plasma at 1 and 12 hours. The method was used to quantify dolutegravir, estimating pharmacokinetic parameters. Agreement between DBS and plasma concentrations was evaluated using linearity and Bland-Altman plots.

RESULTS

The method was validated over the concentration range of 0.4-10 mcg/mL, accuracy was 102.4%-114.8%, and precision was 3.4%-14.7%. The mean recovery was 42.3% (%CV: 8.3). The mean (±SD) dolutegravir concentration in DBS was 37.5% (±3.8%) lower than that in the plasma. DBS-derived and measured plasma concentrations showed strong correlation with linearity (R2 = 0.9804) and Bland-Altman plots. Means (%CV) of area under curve, Cmax, and C24 from the DBS-derived plasma concentration were 37.8 (23.2) mcg·h/mL, 2.7 (24.7) mcg/mL, and 1.34 (31.6) mcg/mL, respectively.

CONCLUSIONS

The application of this simple, accurate, and precise method will expand opportunities for clinical assessment of dolutegravir in resource-limited settings.

Assessment of low volume sampling technologies: utility in nonclinical and clinical studies

Background: Low volume sampling technologies have come a long way; however, their uptake has been slow due to logistical and perceived implementation challenges. Additional studies are needed to overcome these barriers. Materials & methods/results: Here we present two studies where different sampling technologies were evaluated to determine the feasibility of their implementation. First, we evaluated pharmacokinetic profiles for anti-gD in rats using three tail bleed sampling methods, glass capillary tubes, Shimadzu MSW2^® and the Neoteryx Mitra^® microsampler. Second, we evaluated two low volume-sampling methods to measure drug levels from patients treated with anti-A therapeutic. This evaluation used whole blood finger pricks for Neoteryx Mitra and plasma from capillary blood using TASSO OnDemand technology to compare results to established venipuncture collection method. Conclusion: These studies evaluate the feasibility and considerations for implementation of different low volume sampling technologies.