Pharmacokinetics and concentration–effect relationships of therapeutic monoclonal antibodies and fusion proteins

Switching to Conbercept in Diabetic Macular Edema After Unsatisfactory Response to Previous Intravitreal Injection of Ranibizumab

Objective

To assess the functional and anatomical effects of transitioning to conbercept intravitreal injection (IVC) treatment in patients with diabetic macular edema (DME) who had inadequate responses to prior anti-vascular endothelial growth factor (anti-VEGF) injections.

Methods

We retrospectively included eyes with persistent DME after at least 3 injections of intravitreal ranibizumab (IVR). The analysis included the assessment of best corrected visual acuity (BCVA) and central macular thickness (CMT) during 6 months after the switch.

Results

A total of 30 patients (30 eyes) were included. CMT dropped sharply from 437.8±40.67μm at baseline to 363.59±45.09,312.52 ± 39.15, 278.51 ± 37.92, and 292.59 ± 38.09 after 1, 2, 3 and 6 months of IVC, respectively (p <0.001). BCVA in log MAR units was significantly improved from 0.73±0.15 at baseline to 0.50±0.09,0.46±0.72, 0.40±0.06 and 0.48±0.04 after 1, 2, 3 and 6 months, respectively (p <0.001).

Conclusion

Switching to Conbercept effectively improved visual and anatomical structure in DME patients who had not responded satisfactorily to previous anti-VEGF injections.

Advances in biologic and small molecule therapies for hidradenitis suppurativa

INTRODUCTION

Hidradenitis suppurativa (HS) is a chronic, debilitating inflammatory skin disorder characterized by painful nodules, abscesses, fistulae, and scarring with a predilection for flexural regions. Several biologics and small molecule inhibitors are being evaluated in clinical trials for treatment.

AREAS COVERED

The authors discuss the data available from clinical trials and smaller, high-quality studies for existing and emerging biologic and small molecule inhibitor therapies for treatment of HS. Biologics discussed include TNFα, IL-17, IL-23, IL-12/23, and IL-1 inhibitors. Small molecule inhibitors discussed include PDE4, JAK, TYK, IFX-1, and complement cascade inhibitors. Pharmacokinetics and pharmacodynamics for these drugs are also described.

EXPERT OPINION

Trial data and our own experience have shown that about half of HS patients experience improvement with adalimumab. However, there is a significant need for pharmacotherapies with higher efficacy goals as in those used for psoriasis. Many biologics and small molecule inhibitors are being tested in clinical trials. The landscape of upcoming therapies for hidradenitis suppurativa appears promising.

Monoclonal antibodies in diabetic retinopathy

INTRODUCTION

Diabetic retinopathy (DR), as one of the main complications of diabetes, is among the leading causes of blindness and visual impairment worldwide.

AREAS COVERED

Current clinical therapies include photocoagulation, vitrectomy, and anti-vascular endothelial growth factor (VEGF) therapies. Bevacizumab and ranibizumab are two monoclonal antibodies (mAbs) inhibiting angiogenesis. Intravitreal ranibizumab and bevacizumab can decrease the rate of blindness and retinal thickness, and improve visual acuity whether as monotherapy or combined with other treatments. They can increase the efficacy of other treatments and decrease their adverse events. Although administered intravitreally, they also might enter the circulation and cause systemic effects. This study is aimed to review our current knowledge about mAbs, bevacizumab and ranibizumab, in DR including superiorities, challenges, and limitations. Meanwhile, we tried to shed light on new ideas to overcome these limitations. Our latest search was done in April 2021 mainly through PubMed and Google Scholar. Relevant clinical studies were imported.

EXPERT OPINION

Future direction includes detection of more therapeutic targets considering other components of DR pathophysiology and shared pathogenesis of DR and neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, the treat-and-extend regimen, and new ways of drug delivery and other routes of ocular drug administration.

Assessment of exposure-response relationship for bevacizumab in patients with metastatic colorectal cancer

Limited literature is available for bevacizumab exposure-response relationship and there is not a concentration threshold associated with an optimal disease control. This prospective observational study in patients with metastatic colorectal cancer (mCRC) aims to evaluate, in a real-life setting, the relationship between bevacizumab through concentrations at steady state (C_{trough, SS}) and disease control. C_{trough, SS} were drawn, coinciding with the radiological evaluation of the response (progression or clinical benefit). Generalized estimating equations (GEE) analysis was performed. To test the association between C_{trough, SS} in each patient with overall survival (OS) or progression-free survival (PFS), Cox proportional hazard models were developed. Data included 50 bevacizumab C_{trough, SS} from 27 patients. The GEE model did not suggest any positive association between bevacizumab C_{trough, SS} and clinical benefit (OR 0.99, 95% CI: 0.98-1.02, p = 0.863). The Cox regression showed association between higher median C_{trough, SS} with better OS (HR 0.86, 95% CI: 0.73-1.01, p = 0.060), but not with PFS. We cannot confirm a relationship between bevacizumab C_{trough, SS} and clinical benefit but this is the first real-world study trying to show a relationship between bevacizumab C_{trough, SS} and disease control in mCRC. It was conducted in a small sample size which reduces the level of evidence. Further controlled randomized studies with a sufficient number of patients are required.

Engineering of single-domain antibodies for next-generation snakebite antivenoms

Given the magnitude of the global snakebite crisis, strategies to ensure the quality of antivenom, as well as the availability and sustainability of its supply are under development by several research groups. Recombinant DNA technology has allowed the engineering of monoclonal antibodies and recombinant fragments as alternatives to conventional antivenoms. Besides having higher therapeutic efficacy, with broad neutralization capacity against local and systemic toxicity, novel antivenoms need to be safe and cost-effective. Due to the biological and physical chemical properties of camelid single-domain antibodies, with high volume of distribution to distal tissue, their modular format, and their versatility, their biotechnological application has grown considerably in recent decades. This article presents the most up-to-date developments concerning camelid single-domain-based antibodies against major toxins from snake venoms, the main venomous animals responsible for reported envenoming cases and related human deaths. A brief discussion on the composition, challenges, and perspectives of antivenoms is presented, as well as the road ahead for next-generation antivenoms based on single-domain antibodies.

Humanized anti-DEspR IgG4S228P antibody increases overall survival in a pancreatic cancer stem cell-xenograft peritoneal carcinomatosis ratnu/nu model

BACKGROUND

Pancreatic peritoneal carcinomatosis (PPC), with the worst median overall-survival (mOS), epitomizes the incurability of metastatic cancer. Cancer stem cells (CSCs) underpin this incurability. However, inhibitors of CSC-stemness fail to increase mOS in cancer patients despite preclinical tumor-reduction. This shortfall reinforces that preclinical efficacy should be defined by increased mOS in the presence of cancer comorbidities, CSC-heterogeneity and plasticity. The primary objectives of this study are: to test the dual endothelin-1/signal peptide receptor, DEspR, as a nodal therapeutic target in PPC, given DEspR induction in anoikis-resistant pancreatic CSCs, and to validate humanized anti-DEspR antibody, hu-6g8, as a potential therapeutic for PPC.

METHODS

We used heterogeneous pools of CSCs selected for anoikis resistance from reprogrammed Panc1 and MiaPaCa2 tumor cells (TCs), and adherent TCs reprogrammed from CSCs (cscTCs). We used multiple anti-DEspR blocking antibodies (mAbs) with different epitopes, and a humanized anti-DEspR recombinant mAb cross-reactive in rodents and humans, to test DEspR inhibition effects. We measured DEspR-inhibition efficacy on multiple prometastatic CSC-functions in vitro, and on tumorigenesis and overall survival in a CSC-derived xenograft (CDX) nude rat model of PPC with comorbidities.

RESULTS

Here we show that DEspR, a stress-survival receptor, is present on subsets of PDAC Panc1-TCs, TC-derived CSCs, and CSC-differentiated TCs (cscTCs), and that DESpR-inhibition decreases apoptosis-resistance and pro-metastatic mesenchymal functions of CSCs and cscTCs in vitro. We resolve the DNA-sequence/protein-function discordance by confirming ADAR1-RNA editing-dependent DEspR-protein expression in Panc1 and MiaPaCa2 TCs. To advance DEspR-inhibition as a nodal therapeutic approach for PPC, we developed and show improved functionality of a recombinant, humanized anti-DEspR IgG4S228P antibody, hu-6g8, over murine precursor anti-DEspR mabs. Hu-6g8 internalizes and translocates to the nucleus colocalized with cyto-nuclear shuttling galectins-1/3, and induces apoptotic cell changes. DEspR-inhibition blocks transperitoneal dissemination and progression to peritoneal carcinomatosis of heterogeneous DEspR±/CD133 ± Panc1-derived CSCs in xenografted nude rats, improving mOS without chemotherapy-like adverse effects. Lastly, we show DEspR expression in Stage II-IV primary and invasive TCs in the stroma in PDAC-patient tumor arrays.

CONCLUSION

Collectively, the data support humanized anti-DEspR hu-6g8 as a potential targeted antibody-therapeutic with promising efficacy, safety and prevalence profiles for PPC patients.

Systemic conbercept pharmacokinetics and VEGF pharmacodynamics following intravitreal injections of conbercept in patients with retinopathy of prematurity

BACKGROUND

Data on serum vascular endothelial growth factor (VEGF) and drug levels in patients with retinopathy of prematurity (ROP) following intravitreal injections of conbercept (IVC) are lacking.

METHODS

Multicentre, prospective, non-randomised study of patients with aggressive posterior retinopathy of prematurity (APROP) or type 1 ROP who had not received other treatment. All infants received therapy in both eyes plus intravitreal IVC 0.25 mg/0.025 mL in one eye and had at least 6 months of follow-up. Blood samples were collected before and 1 week and 4 weeks after IVC. The main outcome measures were serum conbercept and VEGF concentrations.

RESULTS

Forty infants with APROP or type 1 ROP were enrolled. The mean serum VEGF at baseline and 1 week and 4 weeks after a total of 0.25 mg of IVC was 953.35±311.90 pg/mL, 303.46±181.89 pg/mL and 883.12±303.89 pg/mL, respectively. Serum VEGF 1 week after IVC was significantly lower (p<0.05) than baseline, and at 4 weeks after IVC, it was significantly higher (p<0.05) than at 1 week. There was no significant difference (p>0.05) between baseline and 4 weeks. Serum conbercept was below the limit of quantitation (BLOQ) at baseline and 4 weeks and was 19.81±7.60 ng/mL at 1 week.

CONCLUSION

Serum VEGF 1 week after IVC was significantly lower than baseline but returned to baseline at 4 weeks. Serum conbercept increased at 1 week and was BLOQ at 4 weeks.

Comparison of the effects of intravitreal ranibizumab and aflibercept on retinal vessel diameters in patients with diabetic macular edema

PURPOSE

To evaluate and compare the effects of intravitreal ranibizumab and aflibercept treatment on retinal vessel diameters in patients with diabetic macular edema (DME).

METHODS

Thirty initial-treatment naïve patients with DME who received three loading doses at monthly intervals of intravitreal ranibizumab or aflibercept were retrospectively reviewed. The diameters of the central retinal artery and vein sections at a distance of 1500 microns from the optical disc boundary were measured and evaluated at baseline and after the first, second, and third month of the treatment, using infrared images from optical coherence tomography (OCT) (Heidelberg Engineering, Heidelberg, Germany).

RESULTS

In the superotemporal artery (STA) measurements, the mean basal vessel diameter decreased from 110.00 ± 17.25 μm to 102.60 ± 16.90 μm (p = 0.001) in the third month of the treatment in the ranibizumab group. In the aflibercept group, measurements of the basal STA vessel diameter decreased from 110.20 ± 21.25 μm to 103.93 ± 19.03 μm (p = 0.001) at the third month. The mean basal inferotemporal artery (ITA) vessel diameter was significantly decreased at the third month in both ranibizumab (p = 0.001) and aflibercept groups (p = 0.005). In the superotemporal vein (STV) and inferotemporal vein (ITV) measurements, vessel diameters were found significantly decreased at the end of the third month compared with basal measurements in both the ranibizumab (p = 0.001; p = 0.001, respectively) and aflibercept (p = 0.001; p = 0.004, respectively) treatment groups. The retinal vessel measurements were not found to differ significantly between the two intravitreal treatment agents (p > 0.05).

CONCLUSION

Both intravitreal ranibizumab and aflibercept agents cause a significant narrowing in the retinal vessel diameters in patients with DME after three loading doses at monthly intervals.

A robust enzyme-linked immunosorbent assay to measure serum ramucirumab concentrations

Aim: Ramucirumab, an anti-VEGFR2 monoclonal antibody, has been approved for the treatment of metastatic gastric and colorectal cancer. An assay measuring ramucirumab serum concentrations was needed to investigate its pharmacokinetics and concentration-response relationship. Results: An ELISA was developed and validated according to the international guidelines for ligand-binding assays. Ramucirumab calibration standards ranged from 0.125 to 40 mg/l. Low, middle and high quality controls were spiked at 0.2, 4 and 8 mg/l, respectively. The limits of quantification were established to be 0.125 and 10 mg/l for LLOQ and ULOQ, respectively. No cross-reactivity with anti-VEGF or anti-EGFR was detected. Conclusion: This in-house-developed ELISA is sensitive, accurate, reproducible and suitable for pharmacokinetic studies of ramucirumab.

Evaluation of the Effects of Intravitreal Aflibercept and Ranibizumab on Systemic Inflammatory and Cardiovascular Biomarkers in Patients with Neovascular Age-related Macular Degeneration

Purpose: To investigate the effects of intravitreal ranibizumab (IVR) and intravitreal aflibercept (IVA) on systemic inflammatory and cardiovascular biomarkers in treatment-naive patients with neovascular age-related macular degeneration (nAMD)Methods: This study included 24 eyes of 24 patients treated with 0.5 mg ranibizumab (IVR group) and 25 eyes of 25 patients treated with 2.0 mg aflibercept (IVA group). Complete blood count, C-reactive protein (CRP), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), uric acid (UA), albumin, fibrinogen levels were measured in blood samples before and after the three-monthly loading dose treatment. Neutrophil/lymphocyte ratio (NLR), monocyte/HDL-c ratio (MHR), CRP/albumin ratio (CAR), monocyte/lymphocyte ratio (MLR), platelet/lymphocyte ratio (PLR) were also calculated.Results: A statistically significant decline was determined in post-treatment CRP (P = .002), LDL-c (P < .001) levels, white blood cell (WBC, P = .001), neutrophil (P < .001), monocyte (P = .019) counts and NLR (P = .020), MHR (P = .042), CAR (P = .010) ratios comparing with pre-treatment values in the IVA group. No statistically significant change was found in any of the parameters evaluated in the study in the IVR group. Also, there was no significant change in fibrinogen, lymphocyte count, MLR, HDL-c, UA, PLR, and platelet count values in both groups.Conclusion: Compared to IVR, IVA treatment had a small but significant effect on systemic inflammatory and cardiovascular biomarkers.

Population Pharmacokinetics of Risankizumab in Healthy Volunteers and Subjects with Moderate to Severe Plaque Psoriasis: Integrated Analyses of Phase I-III Clinical Trials

Background and Objective

Risankizumab is an anti-interleukin (IL)-23 monoclonal antibody being developed for treatment of moderate to severe plaque psoriasis. This study provided a comprehensive analysis of risankizumab pharmacokinetics in healthy subjects and patients with plaque psoriasis using data across phase I–III clinical trials.

Methods

Plasma pharmacokinetic data from 1899 subjects, including 13,123 observations, who received single or multiple intravenous or subcutaneous doses of risankizumab (0.01–5 mg/kg intravenous [IV], 200–1200 mg IV, 0.25–1 mg/kg subcutaneous [SC], and 18–300 mg SC) across the phase I–III clinical program were analyzed using a non-linear mixed-effects modeling approach. The developed model was qualified and the clinical relevance of covariates statistically correlated with risankizumab clearance (CL) was evaluated using simulation analyses.

Results

Risankizumab pharmacokinetics were best described using a two-compartment model with first-order absorption and elimination. Risankizumab CL, volume of distribution at steady state (V_ss), and terminal-phase elimination half-life (t_½) were estimated to be approximately 0.31 L/day, 11.2 L, and 28 days, respectively, for a typical 90 kg psoriatic subject, approaching steady-state plasma exposures by week 16 of dosing. Absolute SC bioavailability (F) was 89%. Bodyweight, anti-drug antibody (ADA) titers ≥ 128 (detected in only 1% of ADA-evaluable subjects in phase III studies), baseline serum albumin, high-sensitivity C-reactive protein (hs-CRP), and serum creatinine were statistically correlated with risankizumab CL; however, they had no clinically relevant impact on exposure.

Conclusion

Risankizumab is characterized by dose-proportional, bi-exponential disposition with no difference in exposure between healthy subjects and patients with psoriasis. None of the covariates identified as being statistically correlated with risankizumab CL has a clinically meaningful impact on its exposure with the proposed psoriasis clinical regimen of 150 mg administered SC at weeks 0 and 4, and every 12 weeks thereafter.

ClinicalTrials.gov Identifiers

NCT01577550, NCT02054481, NCT02596217, NCT02684370, NCT02672852, NCT02684357, NCT02694523.

Influence of Antigen Mass on the Pharmacokinetics of Therapeutic Antibodies in Humans

Therapeutic antibodies are increasingly used to treat various diseases, including neoplasms and chronic inflammatory diseases. Antibodies exhibit complex pharmacokinetic properties, notably owing to the influence of antigen mass, i.e. the amount of antigenic targets to which the monoclonal antibody binds specifically. This review focuses on the influence of antigen mass on the pharmacokinetics of therapeutic antibodies quantified by pharmacokinetic modelling in humans. Out of 159 pharmacokinetic studies, 85 reported an influence of antigen mass. This influence led to non-linear elimination decay in 50 publications, which was described using target-mediated drug disposition or derived models, as quasi-steady-state, irreversible binding and Michaelis-Menten models. In 35 publications, the pharmacokinetics was apparently linear and the influence of antigen mass was described as a covariate of pharmacokinetic parameters. If some reported covariates, such as the circulating antigen level or tumour size, are likely to be correlated to antigen mass, others, such as disease activity or disease type, may contain little information on the amount of antigenic targets. In some cases, antigen targets exist in different forms, notably in the circulation and expressed at the cell surface. The influence of antigen mass should be soundly described during the early clinical phases of drug development. To maximise therapeutic efficacy, sufficient antibody doses should be administered to ensure the saturation of antigen targets by therapeutic antibodies in all patients. If necessary, antigen mass should be taken into account in routine clinical practice.

[Pharmacokinetic variability of therapeutic antibodies]

Therapeutic antibodies have been increasingly used for the treatment of various diseases, including cancers and chronic inflammatory diseases. The pharmacokinetic interindividual variability of mAbs is large and influences, at least in part, the clinical response to antibody treatment. This variability is explained by a number of individual sources of variability, which are reviewed here. Some of them are major because they are frequently reported to greatly influence the interindividual variability; notably, increased body size, the presence of anti-drug antibodies, and high antigen mass are associated with decreased antibody concentrations. Other individual sources of variability are of less critical importance. They include sex, age, co-treatments, or genetic polymorphisms of IgG Fc receptors (FcgRs). The interindividual variability of antibody pharmacokinetics should be soundly described in order to design optimal dosing strategy.

Submacular Injection of Ranibizumab as a New Surgical Treatment for Refractory Diabetic Macular Edema

Purpose

In this study, we describe a new surgical technique for the treatment of refractory DME. The technique consists of vitrectomy with ILM peeling with a subretinal injection of ranibizumab.

Methods

This is a prospective interventional noncomparative study including patients with refractory DME. Included patients were subjected to the new surgical technique of pars plana vitrectomy with subretinal injection of ranibizumab.

Results

The study included 19 eyes with refractory macular edema, in which this novel technique was attempted. There were 10 males and 9 females. The age of the patients ranged from 17 to 67 years with a mean of 55.58 ± 13.242 years. The duration of diabetes before enrollment in the study ranged from 7 to 25 years with a mean of 16.3 years. Preoperatively, the mean CMT of the eyes ranged from 352 to 883 microns with mean ± SD of 498.58 ± 152.16 microns. Postoperatively, this improved significantly to 373.5 ± 100.3, 355.9 ± 89.8, and 365.74 ± 120.12 microns at 1, 3, and 6 months, respectively (p ≤ 0.001 for all).

Conclusion

This novel surgical procedure of vitrectomy with ILM peeling with a subretinal injection of ranibizumab is effective in cases of refractory DME. The study has been registered in Contact ClinicalTrials.gov PRS Identifier: NCT03975088.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Inflammatory Bowel Disease

According to recent clinical consensus, pharmacotherapy of inflammatory bowel disease (IBD) is, or should be, personalized medicine. IBD treatment is complex, with highly different treatment classes and relatively few data on treatment strategy. Although thorough evidence-based international IBD guidelines currently exist, appropriate drug and dose choice remains challenging as many disease (disease type, location of disease, disease activity and course, extraintestinal manifestations, complications) and patient characteristics [(pharmaco-)genetic predisposition, response to previous medications, side-effect profile, necessary onset of response, convenience, concurrent therapy, adherence to (maintenance) therapy] are involved. Detailed pharmacological knowledge of the IBD drug arsenal is essential for choosing the right drug, in the right dose, in the right administration form, at the right time, for each individual patient. In this in-depth review, clinical pharmacodynamic and pharmacokinetic considerations are provided for tailoring treatment with the most common IBD drugs. Development (with consequent prospective validation) of easy-to-use treatment algorithms based on these considerations and new pharmacological data may facilitate optimal and effective IBD treatment, preferably corroborated by effectiveness and safety registries.

Clinical Pharmacokinetics and Pharmacodynamics of Infliximab in the Treatment of Inflammatory Bowel Disease

Infliximab was the first monoclonal antibody to be approved for the treatment of pediatric and adult patients with moderately to severely active Crohn's disease (CD) and ulcerative colitis (UC). It has been shown to induce and maintain both clinical remission and mucosal healing in pediatric and adult patients with inflammatory bowel disease (IBD) who are unresponsive or refractory to conventional therapies. The administration of infliximab is weight-based and the drug is administered intravenously. The volume of distribution of infliximab is low and at steady state ranges from 4.5 to 6 L. Therapeutic monoclonal antibodies, such as immunoglobulins, are cleared from the circulation primarily by catabolism. Median infliximab half-life is approximately 14 days. Infliximab concentration-time data in patients with CD and UC have been shown to be highly variable within an individual patient over time and between individuals by multiple population pharmacokinetic models. Covariates that have been identified to account for a part of the observed inter- and intra-individual variability in clearance are the presence of antidrug antibodies, use of concomitant immunomodulators, degree of systemic inflammation, serum albumin concentration, and body weight, which can affect the pharmacodynamic response. This article provides a comprehensive review of the clinical pharmacokinetics and pharmacodynamics of infliximab, as well as the role of therapeutic drug monitoring in the treatment of IBD.

Phage display antibody libraries: A robust approach for generation of recombinant human monoclonal antibodies

Monoclonal antibodies (mAbs) and their derivatives have achieved remarkable success as medicine, targeting both diagnostic and therapeutic applications associated with communicable and non-communicable diseases. In the last 3 to 4 decades, tremendous success has been manifested in the field of cancer therapy, autoimmune diseases, cardiovascular and infectious diseases. MAbs are the fastest growing class of biopharmaceuticals, with more than 25 derivatives are in clinical use and 7 of these have been isolated through phage display technology. Phage display technology has gained impetus in the field of medical and health sciences, as a large repertoire of diverse recombinant antibodies, targeting various antigens have been generated in a short span of time. A prominent number of phage display derived antibodies are already approved for therapy and significant numbers are currently in clinical trials. In this review we have discussed the various strategies employed for generation of monoclonal antibodies; their advantages, limitations and potential therapeutic applications. We also discuss the potential of phage display antibody libraries in isolation of monoclonal antibodies.

Serum Vascular Endothelial Growth Factor Levels before and after Intravitreous Ranibizumab Injection for Retinopathy of Prematurity

Background

Retinopathy of prematurity (ROP) is one of the common complications of prematurity. Intravitreal injection of ranibizumab (IVR), an antivascular endothelial growth factor (VEGF) drug, showed significant benefit for ROP. However, there are concerns about systemic complications of anti-VEGF therapy in preterm infants.

Objectives

To evaluate serum VEGF level in the systemic circulation after IVR and the complications associated with IVR for the premature infants with ROP.

Methods

This prospective investigation assessed the serum concentrations of VEGF in ROP patients before and after IVR therapy. All the infants had binocular retinopathy and received IVR 0.25 mg per eye as the primary treatment. Serum samples were collected 1 day prior to injection and 1 day, 3 days, and 7 days after IVR treatment. Serum VEGF level was measured by the enzyme-linked immunosorbent assay (ELISA).

Results

Fifteen infants (6 girls and 9 boys) were enrolled. The serum concentrations of VEGF 1 day before and 1 day, 3 days, and 7 days after a total of 0.5 mg intravitreal injections of ranibizumab were 226.9 (198.4, 272.4), 12.8 (7.0, 22.4), 16 (12.0, 20.8), and 33.7 (24.0, 48.0) pg/ml, respectively. Serum VEGF levels decreased significantly at 1 day, 3 days, and 7 days after IVR treatment compared with pretreatment concentration (P < 0.05). Compared to days 1 and 3 after IVR, serum VEGF level at 7 days after IVR treatment increased significantly (P < 0.05).

Conclusion

Serum VEGF levels in patients with ROP were suppressed for at least 7 days after IVR treatment. Although the clinical significance of this phenomenon is uncertain, its safety profile requires further investigation.

Liposomes targeted to MHC-restricted antigen improve drug delivery and antimelanoma response

Purpose

Melanoma is the most aggressive form of skin cancer. Chemotherapy at a late stage fails due to low accumulation in tumors, indicating the need for targeted therapy.

Materials and methods

To increase drug uptake by tumor cells, we have targeted doxorubicin-containing liposomes using a T-cell receptor (TCR)-like antibody (scFv G8 and Hyb3) directed against melanoma antigen A1 (MAGE-A1) presented by human leukocyte antigen A1 (M1/A1). With the use of flow cytometry and confocal microscopy, we have tested our formulation in vitro. In vivo pharmacokinetics was done in tumor-free nu/nu mice, while biodistribution and efficacy study was done in nu/nu mice xenograft.

Results

We demonstrated two to five times higher binding and internalization of these immunoliposomes by M1⁺/A1⁺ melanoma cells in vitro in comparison with nontargeted liposomes. Cytotoxicity assay showed significant tumor cell kill at 10 µM doxorubicin (DXR) for targeted vs nontargeted liposomes. In vivo pharmacokinetics of nontargeted and targeted liposomes were similar, while accumulation of targeted liposomes was 2- to 2.5-fold and 6.6-fold enhanced when compared with nontargeted liposomes and free drug, respectively. Notably, we showed a superior antitumor activity of MAGE-A1-targeted DXR liposomes toward M1⁺/A1⁺ expressing tumors in mice compared with the treatment of M1⁻/A1⁺ tumors. Our results indicate that targeted liposomes showed better cytotoxicity in vitro and pharmacokinetics in vivo.

Conclusion

Liposomes decorated with TCR-mimicking scFv antibodies effectively and selectively target antigen-positive melanoma. We showed that DXR-loaded liposomes coupled to anti-M1/-A1 scFv inflict a significant antitumor response. Targeting tumor cells specifically promotes internalization of drug-containing nanoparticles and may improve drug delivery and ultimately antitumor efficacy. Our data argue that targeting MAGE in A1 context, by nanosized carriers decorated with TCR-like antibodies mimicking scFv, can be used as a theragnostic platform for drug delivery, immunotherapy, and potentially imaging, and diagnosis of melanoma.

Host genetic profiling to increase drug safety in colorectal cancer from discovery to implementation

Adverse events affect the pharmacological treatment of approximately 90% of colorectal cancer (CRC) patients at any stage of the disease. Chemotherapy including fluoropyrimidines, irinotecan, and oxaliplatin is the cornerstone of the pharmacological treatment of CRC. The introduction of novel targeted agents, as anti-EGFR (i.e. cetuximab, panitumumab) and antiangiogenic (i.e. bevacizumab, ziv-aflibercept, regorafenib, and ramucirumab) molecules, into the oncologist's toolbox has led to significant improvements in the life expectancy of advanced CRC patients, but with a substantial increase in toxicity burden. In this respect, pharmacogenomics has largely been applied to the personalization of CRC chemotherapy, focusing mainly on the study of inhered polymorphisms in genes encoding phase I and II enzymes, ATP-binding cassette (ABC)/solute carrier (SLC) membrane transporters, proteins involved in DNA repair, folate pathway and immune response. These research efforts have led to the identification of some validated genetic markers of chemotherapy toxicity, for fluoropyrimidines and irinotecan. No validated genetic determinants of oxaliplatin-specific toxicity, as peripheral neuropathy, has thus far been established. The contribution of host genetic markers in predicting the toxicity associated with novel targeted agents' administration is still controversial due to the heterogeneity of published data. Pharmacogenomics guidelines have been published by some international scientific consortia such as the Clinical Pharmacogenomics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group (DPWG) strongly suggesting a pre-treatment dose adjustment of irinotecan based on UGT1A1*28 genotype and of fluoropyrimidines based on some DPYD genetic variants, to increase treatment safety. However, these recommendations are still poorly applied at the patient's bedside. Several ongoing projects in the U.S. and Europe are currently evaluating how pharmacogenomics can be implemented successfully in daily clinical practice. The majority of drug-related adverse events are still unexplained, and a great deal of ongoing research is aimed at improving knowledge of the role of pharmacogenomics in increasing treatment safety. In this review, the issue of pre-treatment identification of CRC patients at risk of toxicity via the analysis of patients' genetic profiles is addressed. Available pharmacogenomics guidelines with ongoing efforts to implement them in clinical practice and new exploratory markers for clinical validation are described.

Pharmacokinetics of Bevacizumab in Three Patients Under the Age of 3 Years with CNS Malignancies

Background

Bevacizumab is a recombinant antibody that is increasingly used in pediatric malignancies. The pharmacokinetics of bevacizumab in pediatric patients have been shown to be influenced by tumor localization and body weight. In this report, we present data on the pharmacokinetics and safety of bevacizumab in children under the age of 3 years with central nervous system (CNS) malignancies.

Methods

Three patients (mean age 22 months) were treated with intravenous bevacizumab 10 mg/kg every 2 weeks. In total, 20 trough and peak bevacizumab concentrations of 10 treatment cycles were obtained at steady state.

Results

Bevacizumab was generally well-tolerated in this age group. The mean trough concentration was 127 ± 29 µg/ml (range 77–155), and the mean peak concentration was 149 ± 13 µg/ml (range 113–157). Trough and peak levels were stable upon repeated treatment cycles in the same patient. In contrast, we determined strong interindividual variations in trough levels. Whereas the plasma concentration of the oldest patient matched the prediction of a previously published model, younger patients showed markedly higher trough levels.

Conclusions

Serum peak concentrations of bevacizumab in children under the age of 3 years with CNS malignancies are in a similar magnitude to that found in older children and adults. Thus, a dosing schedule of bevacizumab 10 mg/kg every 2 weeks can be considered sufficient and safe, even in very young children. We further show that very young children with CNS malignancies show a markedly reduced plasma clearance, possibly related to lower body weight or differences in clearance mechanisms of antibodies.

Label-Free Quantification of Anti-TNF-α in Patients Treated with Adalimumab Using an Optical Biosensor

This study describes the development of an immunosensory label-free quantification methodology based on surface plasmon resonance (SPR) and its applicability in measuring/evaluating therapeutic drug monitoring (TDM) of anti-TNF-α monoclonal antibody (adalimumab) in rheumatoid arthritis (RA) patients. The experimental parameters evaluated in this study were immobilising ligands by pre-concentration assays, sensor surface regeneration, ascertaining the method’s sensitivity and correlating the results from quantifying plasma samples by ELISA immunoassay. The results showed that TNF-α quantification values (in RU) were significantly different when comparing patients (~50–250 RU) to controls (~10–20 RU). Likewise, there was 0.97 correlation for patients and 0.91 for healthy volunteers using SPR and ELISA comparison methodologies. SPR immunosensory detection provided a precise, sensitive strategy, along with real-time determination, for quantifying adalimumab, having great potential for clinical routine regarding TDM.

SYSTEMIC PHARMACOKINETICS AND PHARMACODYNAMICS OF INTRAVITREAL AFLIBERCEPT, BEVACIZUMAB, AND RANIBIZUMAB

After monthly intravitreal injections, the systemic exposures of aflibercept, bevacizumab, and ranibizumab were distinct and correlated with different reductions in plasma free–vascular endothelial growth factor, which could provide biologic plausibility for potential differences in systemic adverse events.

Purpose:

To evaluate the systemic pharmacokinetics (PKs) of aflibercept, bevacizumab, and ranibizumab in patients with neovascular age-related macular degeneration (AMD), diabetic macular edema (DME), or retinal vein occlusion (RVO).

Methods:

Prospective, open-label, nonrandomized clinical trial of patients with AMD, DME, or RVO who were antivascular endothelial growth factor (VEGF) naïve or had not received anti-VEGF for ≥4 months. Patients received 3 monthly intravitreal injections of aflibercept 2.0 mg, bevacizumab 1.25 mg, or ranibizumab (0.5 mg for AMD/RVO, 0.3 mg for DME). The main outcome measures were serum PKs and plasma free-VEGF concentrations after the first and third injections.

Results:

A total of 151 patients were included. In AMD/DME/RVO, systemic exposure to each drug was highest with bevacizumab, then aflibercept, and lowest with ranibizumab. Ranibizumab cleared from the bloodstream more quickly than bevacizumab or aflibercept. Aflibercept treatment resulted in the greatest reductions in plasma free-VEGF relative to baseline levels, whereas ranibizumab treatment resulted in the smallest decreases in plasma free-VEGF.

Conclusion:

The three anti-VEGF treatments examined in this analysis demonstrated notable differences in systemic PKs. Generally, the reduction in plasma free-VEGF levels correlated with elevated levels of circulating anti-VEGF agents, with the reduction in free-VEGF levels greatest with aflibercept and least with ranibizumab.

Changes in systemic vascular endothelial growth factor levels after intravitreal injection of aflibercept in infants with retinopathy of prematurity

BACKGROUND

To investigate the levels of VEGF in the systemic circulation of patients with type 1 ROP who received intravitreal injections of 1 mg (0.025 mL) aflibercept (IVA) or 0.625 mg (0.025 mL) bevacizumab (IVB).

METHODS

Patients who had type 1 ROP and received either IVA or IVB were enrolled in this prospective study. Serum and plasma samples were collected prior to and up to 12 weeks after IVB or IVA treatment. The serum and plasma VEGF levels were measured using enzyme-linked immunosorbent assays (ELISAs), and the platelet levels in the blood were also quantified. The serum and plasma levels of VEGF, as well as the ratio of VEGF to platelet count (VEGF/PLT) were measured prior to and up to 12 weeks after anti-VEGF treatment.

RESULTS

In total, 14 patients with type 1 ROP were enrolled in this study; five patients received IVA, and nine patients received IVB. Following either IVA or IVB treatment, all the eyes (100%) showed complete resolution of ROP-induced abnormal neovascularization and presented continued vascularization toward the peripheral retina. Compared to baseline, the serum VEGF levels were significantly reduced in the ROP patients up to 12 weeks after either IVA or IVB treatments (all P < 0.05). At 2, 4, and 8 weeks after intravitreal injection, the serum VEGF levels were more suppressed in the IVB group than in the IVA group (P = 0.039, P = 0.004, and P = 0.003, respectively). The serum VEGF/PLT ratio after IVA or IVB showed similar reductions and trends as the serum VEGF data. Changes in the plasma VEGF levels could not be properly assessed because some of the samples had VEGF levels below the detection limit of the ELISA.

CONCLUSIONS

Serum VEGF levels and the VEGF/PLT ratio in patients with type 1 ROP were suppressed for 3 months after treatment with either IVA or IVB, but the suppression of systemic VEGF was more pronounced in patients treated with IVB than those treated with IVA.

Cetuximab Pharmacokinetics Influences Overall Survival in Patients With Head and Neck Cancer

BACKGROUND

A retrospective study was conducted to analyze interindividual variability of cetuximab pharmacokinetics and its influence on survival (progression-free survival and overall survival [OS]) in a cohort of head and neck squamous cell carcinoma (HNSCC).

METHODS

Thirty-four patients received cetuximab as an infusion loading dose of 400 mg/m followed by weekly infusions of 250 mg/m. Twenty-one patients had locally advanced HNSCC, and 13 had metastatic/recurrent HNSCC. Cetuximab concentrations were measured by the enzyme-linked immunosorbent assay, and its pharmacokinetics was analyzed by a population approach. Survivals were analyzed with the log-rank test.

RESULTS

Cetuximab pharmacokinetics was best described using a 2-compartment model with both first-order and saturable (zero-order) eliminations. Estimated pharmacokinetic parameters (%CV) were central volume of distribution V1 = 3.18 L (6%), peripheral volume of distribution V2 = 5.4 L (42%), elimination clearance CL = 0.57 L/d (31%), distribution clearance Q = 0.64 L/d, and zero-order elimination rate k0 = 6.72 mg/d (29%). Both V1 and V2 increased with the body surface area. Adjunction of chemotherapy reduced CL and increased k0. OS was inversely related with cetuximab global clearance (P = 0.007) and was higher in patients with severe radiation dermatitis (P = 0.005).

CONCLUSIONS

Cetuximab pharmacokinetics in patients with HNSCC can be described using a 2-compartment model combining linear and nonlinear mechanisms of elimination. OS is associated with both cetuximab global clearance and severe radiation dermatitis.

SERUM VASCULAR ENDOTHELIAL GROWTH FACTOR AFTER BEVACIZUMAB OR RANIBIZUMAB TREATMENT FOR RETINOPATHY OF PREMATURITY

PURPOSE

To investigate vascular endothelial growth factor (VEGF) levels in the systemic circulation after intravitreal injections of bevacizumab (IVB) or ranibizumab (IVR) in patients with Type 1 retinopathy of prematurity (ROP).

METHODS

Patients who had Type 1 ROP and received IVB or IVR were enrolled. Serum samples were collected before and up to 12 weeks after IVB or IVR treatment. The main outcome measurements were serum levels of VEGF up to 12 weeks after anti-VEGF treatment.

RESULTS

In total, 10 patients with Type 1 ROP were enrolled in this study. All the eyes had complete resolution of abnormal neovascularization of ROP after IVB or IVR. In the direct comparison of IVB with IVR, serum VEGF was found to be suppressed more in patients with Type 1 ROP who received IVB treatment, compared with those who received IVR treatment (P = 0.01, P = 0.03, and P = 0.03, respectively, 2, 4, and 8 weeks after intravitreal injection).

CONCLUSION

Serum VEGF levels in patients with Type 1 ROP were suppressed for 2 months after treatment with IVB, and VEGF levels were less affected after IVR treatment. Further studies are warranted to investigate the long-term effects of VEGF changes in ROP patients.

[Analysis of cardiovascular diseases after the upload phase with intravitreal ranibizumab and bevacizumab in patients with exudative age-related macular degeneration]

BACKGROUND

The intravitreal administration of vascular endothelial growth factor (VEGF) inhibitors is the gold standard in the treatment of exudative age-related macular degeneration (AMD) but the possible risks of systemic, particularly cardiovascular side effects are still discussed.

PATIENTS AND METHODS

We prospectively followed 111 patients at the University Hospital in Göttingen with exudative AMD and intravitreal ocular treatment with bevacizumab and ranibizumab during the upload phase of 3 months using a questionnaire for documentation of possible cardiovascular events.

RESULTS

In 5 out of 111 patients angina pectoris was observed and in 6 patients the antihypertensive medication had to be increased. No differences were found between bevacizumab and ranibizumab. A patient with pre-existing cardiovascular diseases suffered a stroke in the upload phase but no thromboembolic events were observed in the other patients.

CONCLUSION

In this small but prospective clinical study no increased risk for cardiovascular events during the upload phase of the VEGF inhibitors ranibizumab and bevacizumab could be detected when taking the age and pre-existing cardiovascular diseases into consideration.

Pathologic Response of HER2-positive Gastric Cancer to Trastuzumab-based Chemotherapy

Trastuzumab-based chemotherapy is now a standard approach for patients with human epidermal growth factor receptor 2 (HER2)-positive advanced gastric cancer. However, histopathologic changes after treatment have yet to be elucidated. This study aims to characterize the histologic response of gastric cancer to trastuzumab treatment and its correlation with HER2 status. Twenty-one advanced HER2-positive gastric cancers treated with trastuzumab-based chemotherapy, including 10 surgically resected specimens and 11 biopsy samples from patients with inoperable tumors, were evaluated for the histologic responses and HER2 status of residual cells. We also reviewed, as controls, 10 cases undergoing surgical resection of tumors after chemotherapy without trastuzumab. Complete and partial histologic responses were obtained in 2 and 8 of the surgical cases, respectively. HER2-positive neoplastic cells were recognized at least focally in the 8 cases. Notably, the proportion of HER2-positive cells was always higher in superficial (mucosal/submucosal) layers than in deeper layers. Three specimens contained HER2-positive neoplastic cells exclusively in the superficial area or intravascular space, whereas deeply invasive or metastatic components almost completely disappeared or were HER2 negative when still present. In contrast, HER2-negative cells or residual tumor cells in control cases tended to survive as well or better in deeply invasive areas or in metastases than in superficial areas. Biopsy samples from nonoperative patients remained HER2 positive after treatment in 8 of 11 patients. Our observations suggest that HER2-positive neoplastic cells tend to survive within superficial areas or intravascular spaces after trastuzumab therapy, even when deeply invasive or metastatic lesions responded well to therapy.

Calibrated flux measurements reveal a nanostructure-stimulated transcytotic pathway

Transport of therapeutic agents across epithelial barriers is an important element in drug delivery. Transepithelial flux is widely used as a measure of transit across an epithelium, however it is most typically employed as a relative as opposed to absolute measure of molecular movement. Here, we have used the calcium switch approach to measure the maximum rate of paracellular flux through unencumbered intercellular junctions as a method to calibrate the flux rates for a series of tracers ranging in 0.6-900kDa in size across barriers composed of human colon epithelial (Caco-2) cells. We then examined the effects of nanostructured films (NSFs) on transepithelial transport. Two different NSF patterns were used, Defined Nanostructure (DN) 2 imprinted on polypropylene (PP) and DN3 imprinted on polyether ether ketone (PEEK). NSFs made direct contact with cells and decreased their barrier function, as measured by transepithelial resistance (TER), however cell viability was not affected. When NSF-induced transepithelial transport of Fab fragment (55kDa) and IgG (160kDa) was measured, it was unexpectedly found to be significantly greater than the maximum paracellular rate as predicted using cells cultured in low calcium. These data suggested that NSFs stimulate an active transport pathway, most likely transcytosis, in addition to increasing paracellular flux. Transport of IgG via transcytosis was confirmed by immunofluorescence confocal microscopy, since NSFs induced a significant level of IgG endocytosis by Caco-2 cells. Thus, NSF-induced IgG flux was attributable to both transcytosis and the paracellular route. These data provide the first demonstration that transcytosis can be stimulated by NSFs and that this was concurrent with increased paracellular permeability. Moreover, NSFs with distinct architecture paired with specific substrates have the potential to provide an effective means to regulate transepithelial transport in order to optimize drug delivery.

Genotypes Affecting the Pharmacokinetics of Anticancer Drugs

Cancer treatment is becoming more and more individually based as a result of the large inter-individual differences that exist in treatment outcome and toxicity when patients are treated using population-based drug doses. Polymorphisms in genes encoding drug-metabolizing enzymes and transporters can significantly influence uptake, metabolism, and elimination of anticancer drugs. As a result, the altered pharmacokinetics can greatly influence drug efficacy and toxicity. Pharmacogenetic screening and/or drug-specific phenotyping of cancer patients eligible for treatment with chemotherapeutic drugs, prior to the start of anticancer treatment, can identify patients with tumors that are likely to be responsive or resistant to the proposed drugs. Similarly, the identification of patients with an increased risk of developing toxicity would allow either dose adaptation or the application of other targeted therapies. This review focuses on the role of genetic polymorphisms significantly altering the pharmacokinetics of anticancer drugs. Polymorphisms in DPYD, TPMT, and UGT1A1 have been described that have a major impact on the pharmacokinetics of 5-fluorouracil, mercaptopurine, and irinotecan, respectively. For other drugs, however, the association of polymorphisms with pharmacokinetics is less clear. To date, the influence of genetic variations on the pharmacokinetics of the increasingly used monoclonal antibodies has hardly been investigated. Some studies indicate that genes encoding the Fcγ-receptor family are of interest, but more research is needed to establish if screening before the start of therapy is beneficial. Considering the profound impact of polymorphisms in drug transporters and drug-metabolizing enzymes on the pharmacokinetics of chemotherapeutic drugs and hence, their toxicity and efficacy, pharmacogenetic and pharmacokinetic profiling should become the standard of care.

The FCGR3A polymorphism predicts the response to rituximab-based therapy in patients with non-Hodgkin lymphoma: a meta-analysis

Epidemiological studies have assessed the association between Fc gamma receptor IIIA (FCGR3A) 158 V/F and the response to rituximab-based therapy in patients with non-Hodgkin lymphoma (NHL), but the findings have been inconsistent. We performed this meta-analysis to obtain a better assessment of this relationship. Electronic database searches were conducted for relevant studies. A pooled odds ratio (OR) with a 95 % confidence interval (95 % CI) was used to assess the strength of the association. Analyses of the subgroup and publication bias were conducted. A total of 10 studies involving 1050 patients were analyzed. In all the genetic models, no clear relationship was found between the FCGR3A 158 V/F polymorphism and the response to rituximab-based therapy in NHL patients. When categorized by ethnicity, Asian individuals with the FCGR3A 158 V/V allele (OR = 4.37; 95 % CI = 1.07-17.73; P = 0.039) or the non-F/(FV + VV) (OR = 2.50; 95 % CI = 1.04-5.98; P = 0.040) allele have a significantly higher complete response rate (CR) compared to FF individuals. No obvious heterogeneities were observed. In addition, no statistical evidence for a publication bias was found. Our study suggested that the FCGR3A 158 V/F polymorphism can predict the treatment response to rituximab-based chemotherapy in NHL patients, especially for Asian individuals.

Clinical Pharmacokinetics and Pharmacodynamics of Monoclonal Antibodies Approved to Treat Rheumatoid Arthritis

Monoclonal antibodies (mAbs) are increasingly used to treat rheumatoid arthritis (RA). At present, anti-tumor necrosis factor-α drugs (infliximab, adalimumab, certolizumab pegol, and golimumab), rituximab, and tocilizumab are approved for RA treatment. This review focuses on the pharmacokinetics and pharmacodynamics of mAbs approved in RA. Being large proteins, mAbs exhibit complex pharmacokinetic and pharmacodynamic properties. In particular, owing to the interactions of mAbs with their antigenic targets, the pharmacokinetics of mAbs depends on target turnover and exhibits non-specific (linear) and target-mediated (often nonlinear) clearances. Their volume of distribution is low (3-4 L) and their elimination half-life usually ranges from 2 to 3 weeks. The inter-individual pharmacokinetic variability of mAbs is usually large and is partly explained by differences in antigenic burden or by anti-drug antibodies, which accelerate mAb elimination. The inter-individual variability of clinical response is large and influenced by the pharmacokinetics. The analysis of mAbs concentration-effect relationship relies more and more often on pharmacokinetic-pharmacodynamic modeling; these models being suitable for dosing optimization. Even if adverse effects of mAbs used in RA are well known, the relationship between mAb concentration and adverse effects is poorly documented, especially for anti-tumor necrosis factor-α mAbs. Overall, RA patients treated with mAbs should benefit from individualized dosing strategies. Because of the complexity of their pharmacokinetics and mechanisms of action, the current dosing strategy of mAbs is not based on sound knowledge. New studies are needed to assess individual dosing regimen, adjusted notably to disease activity.

EGFR targeted thermosensitive liposomes: A novel multifunctional platform for simultaneous tumor targeted and stimulus responsive drug delivery

The epidermal growth factor receptor (EGFR) is a promising target for anti-cancer therapy. The aim of this study was to design thermosensitive liposomes (TSL), functionalized with anti-EGFR ligands for targeted delivery and localized triggered release of chemotherapy. For targeting, EGFR specific peptide (GE11) and Fab' fragments of cetuximab were used and the effect of ligand density on in vitro tumor targeting was investigated. Ligand conjugation did not significantly change the physicochemical characteristics of liposomes. Fab'-decorated TSL (Fab'-TSL) can specifically and more efficiently bind to the EGFR overexpressed cancer cells as compared to GE11 modified TSL. Calcein labeled Fab'-TSL showed adequate stability at 37°C in serum (<4% calcein released after 1h) and a temperature dependent release at above 40°C. FACS analysis and live cell imaging showed efficient and EGFR mediated cellular association as well as dramatic intracellular cargo release upon hyperthermia. Fab'-conjugation and hyperthermia induced enhanced tumor cell cytotoxicity of doxorubicin loaded TSL. The relative cytotoxicity of Fab'-TSL was also correlated to EGFR density on the tumor cells. These results suggest that Fab'-TSL showed great potential for combinational targeted and triggered release drug delivery.

Subfoveal choroidal thickness changes after intravitreal bevacizumab injection for neovascular age-related macular degeneration and diabetic macular edema

The purpose of this study was to investigate the changes in subfoveal choroidal thickness (SFCT) after intravitreal injection of bevacizumab (IVB) for neovascular age-related macular degeneration (AMD) and diabetic macular edema (DME). This retrospective, consecutive, interventional case series study included 43 eyes [21 affected eyes with neovascular AMD (AMD group) and 22 affected eyes with DME (DME group)] which were treated with 1.25 mg/0.5 ml IVB and 43 untreated fellow eyes of 43 patients. SFCT was measured in all 86 eyes at baseline before IVB injection and at day 1, week 1, and month 1 after injection by use of enhanced depth imaging optical coherence tomography (EDI OCT). Central foveal thickness (CFT) and best-corrected visual acuity were analyzed at baseline and during follow-up visits. Main outcome measure was change in SFCT in 1 month after treatment. All 43 eyes treated with IVB showed a significant reduction in SFCT. Mean SFCT in treated eyes decreased from 237.1 ± 75.3 µm at baseline to 214.0 ± 65.7 µm at day 1, 205.4 ± 59.7 at week 1, and 222.7 ± 73.3 at month 1, whereas SFCT in fellow eyes changed from 228.4 ± 63.6 at baseline to 224.5 ± 68.5 at day 1, 220.4 ± 72.1 at week 1, and 226.9 ± 74.0 at month 1. SFCT demonstrated a similar trend toward decrease in both groups. CFT decreased significantly and visual acuity improved significantly. SFCT decreased significantly in AMD and DME eyes following injection. The decreasing effect of bevacizumab on choroidal thickness was highest at first week and continued to the end of first month after injection.

Pharmacokinetic characteristics of therapeutic antibodies

Because of their high molecular weight and their highly hydrophilic character, therapeutic antibodies behave differently in terms of absorption, distribution and elimination compared to conventional drugs. Also, their pharmacokinetic profile varies significantly among individuals. After subcutaneous administration, antibodies are absorbed via the lymphatic system and become systemically bioavailable with some delay. The physicochemical properties of the molecules hinder their distribution from the bloodstream into the tissue. Elimination occurs by proteolysis in various organs (skin, muscle, liver), but mainly within the reticuloendothelial system. Also relevant is the elimination through target antigens (especially in the case of cell-bound target antigens) as well as a recycling process through binding to the neonatal Fc receptor that provides protection from lysosomal degradation. Depending on the immunogenicity of the therapeutic antibody and the individual immune response, neutralizing antibodies can develop. Pharmacokinetic conditions can be optimized by coadministration of, for example, methotrexate. Moreover, risk factors for the loss of immunological tolerance, such as on-demand therapy or elective switching of therapeutic antibodies, should be avoided.

Clinical Decision Support Tools: The Evolution of a Revolution

Dashboard systems for clinical decision support integrate data from multiple sources. These systems, the newest in a long line of dose calculators and other decision support tools, utilize Bayesian approaches to fully individualize dosing using information gathered through therapeutic drug monitoring. In the treatment of inflammatory bowel disease patients with infliximab, dashboards may reduce therapeutic failures and treatment costs. The history and future development of modern Bayesian dashboard systems is described.

Dashboard systems: Pharmacokinetic/pharmacodynamic mediated dose optimization for monoclonal antibodies

Many marketed drugs exhibit high variability in exposure and response. While these drugs are efficacious in their approved indications, finding appropriate dose regimens for individual patients is not straightforward. Similar dose adjustment problems are also seen with drugs that have a complex relationship between exposure and response and/or a narrow therapeutic window. This is particularly true for monoclonal antibodies, where prolonged dosing at a sub-therapeutic dose can also elicit anti-drug antibodies which will further compromise safety and efficacy. Thus, finding appropriate doses quickly would represent a substantial improvement in healthcare. Dashboard systems, which are decision-support tools, offer an improved, convenient means of tailoring treatment for individual patients. This article reviews the clinical need for this approach, particularly with monoclonal antibodies, the design, development, and testing of such systems, and the likely benefits of dashboard systems in clinical practice. We focus on infliximab for reference.

Therapeutic Monoclonal Antibodies: What Headache Specialists Need to Know

BACKGROUND

Monoclonal antibodies (mAbs) are now an important part of the treatment armamentarium for a wide range of conditions including cancer, autoimmune diseases, inflammatory diseases of the joint and bowel, transplant rejection, and multiple sclerosis. Significant progress over the last 30 years in the development of therapeutic mAbs has resulted in improved efficacy and safety. Monoclonal antibodies approved for the treatment of neurological illnesses so far are limited to use in multiple sclerosis. Several therapeutic mAbs have completed phase 2 clinical trials for migraine prevention, and there are phase 3 trials underway for migraine prophylaxis and for cluster headache at the time of this writing.

AIM

The purpose of this review is to discuss the characteristics of mAbs, including their mechanism of action and safety profile, and briefly describe the mAbs being evaluated for the prevention of migraine and cluster headaches.

SUMMARY

Monoclonal antibodies have several features that distinguish them from small molecules, including very high selectivity, relatively long half-life that generally allows for once or twice monthly dosing, and significantly reduced potential for drug-drug interactions or other nontarget related toxicities. The clinical development of mAbs that target calcitonin gene-related peptide and its receptor is underway and will evaluate this promising new drug class for the prevention of migraine and cluster headache.

Biologic concentration testing in inflammatory bowel disease

Anti-TNF medications have revolutionized the care of patients with inflammatory bowel disease. However, despite an initial robust effect, loss of response is common and long-term results are disappointing. Much of this lack of durability may be due to inadequate dose optimization, and recent studies suggest a correlation between serum drug concentrations and clinical outcomes. Currently, in clinical practice, measurement of drug concentrations and antibodies to drug are typically performed only when a patient presents with active inflammatory bowel disease symptoms or during a potential immune-mediated reaction to anti-TNF ("reactive" setting). However, proactive monitoring of anti-TNF concentrations with titration to a therapeutic window (i.e., therapeutic concentration monitoring) represents a new strategy with many potential clinical benefits including prevention of immunogenicity, less need for IFX rescue therapy, and greater durability of IFX treatment. This review will cover the salient features of anti-TNF pharmacokinetics and pharmacodynamics and provide a rational approach for the use of anti-TNF concentration testing in both the reactive and proactive settings.

Monoclonal Antibodies and Progressive Multifocal Leukoencephalopathy

Monoclonal antibodies have become an important treatment option for a number of serious conditions. Concerns have arisen about the potential association of these products with progressive multifocal leukoencephalopathy (PML). A list of monoclonal antibodies authorized for sale was derived from the Health Canada Drug Product Database. Case reports of PML after exposure to a monoclonal antibody authorized for use in Canada were retrieved by searching Canada Vigilance and WHO adverse event databases and through a Pub MED/Medline literature search. 182 adverse event case reports were retrieved (adalimumab -1 case, alemtuzumab-14, bevacizumab -3, cetuximab -1, efalizumab - 8, ibritumomab tiuxetan-5, infliximab-4, natalizumab-32, and rituximab-114). The Canadian Product Monographs for natalizumab and ritiximab contain box warnings for PML. A natalizumab registry has been established.

Systemic pharmacokinetics following intravitreal injections of ranibizumab, bevacizumab or aflibercept in patients with neovascular AMD

Background

Data comparing systemic exposure and systemic vascular endothelial growth factor (VEGF) suppression of ranibizumab, bevacizumab and aflibercept following intravitreal injection are lacking.

Methods

Fifty-six patients with wet age-related macular degeneration received intravitreal ranibizumab (0.5 mg), bevacizumab (1.25 mg), or aflibercept (2.0 mg). Serum pharmacokinetics and plasma free VEGF were evaluated after the first and third injections.

Results

Following the first dose, systemic exposure to aflibercept was 5-, 37-, and 9-fold higher than ranibizumab, whereas, bevacizumab was 9-, 310-, and 35-fold higher than ranibizumab, based on geometric mean ratio of peak and trough concentrations and area under the curve, respectively. The third dose showed accumulation of bevacizumab and aflibercept but not ranibizumab. Aflibercept substantially suppressed plasma free VEGF, with mean levels below lower limit of quantitation (10 pg/mL) as early as 3 h postdose until ≥7 days postdose. Mean free (unbound) VEGF levels with ranibizumab were largely unchanged, with mean trough level of 14.4 pg/mL compared with baseline of 17 pg/mL.

Conclusions

There are notable differences in systemic pharmacokinetics and pharmacodynamics among anti-VEGF treatments after intravitreal administration. All three agents rapidly moved into the bloodstream, but ranibizumab very quickly cleared, whereas bevacizumab and aflibercept demonstrated greater systemic exposure and produced a marked reduction in plasma free VEGF.

Trial registration number

NCT02118831.

Monoclonal antibodies: Pharmacokinetics as a basis for new dosage regimens?

Complete monoclonal IgG antibodies which are in use in clinical practice share some pharmacological properties resulting in high concentrations in plasma. This fact is reflected in their low volumes of distribution, which can also be correlated with a high molecular weight and water solubility. This feature allows a novel approach to be applied to the dosing schedule for this group of drugs with fixed doses being used instead of the initially developed weight- or body surface-adjusted dosing schedules. In addition, the development of a new formulation containing hyaluronidase allows a subcutaneous route of administration to be used, because hyaluronidase creates a space in the subcutaneous tissue that helps antibody absorption. This method requires higher doses, but has allowed testing the feasibility of administering a fixed dose, with no individual dose adjustments based on weight or body surface. Moreover, loading doses are not needed, because the first dose results, within 3 weeks, in minimum concentrations that are higher than effective concentrations.

Pharmacokinetics of pazopanib administered in combination with bevacizumab

A combination of monoclonal antibody that binds and inhibits effects induced by vascular endothelial growth factor and tyrosine kinase inhibitor of vascular endothelial growth factor receptor represents a promising concept to block pathological angiogenesis completely. A phase I study combining daily oral pazopanib and bevacizumab (given iv every 2 weeks) was performed in order to determine the maximum tolerated dose of the two drugs in combination. Pazopanib pharmacokinetics were evaluated to compare pharmacokinetic parameters given alone and those observed on the day of the bevacizumab administration. Plasma pazopanib concentrations were obtained in 25 patients treated at two dose levels (400 or 600 mg) at Day 1 (given alone) and Day 15 (the day of the 7.5 mg/kg bevacizumab infusion), and analyzed using the NONMEM program. The apparent oral clearance (CL/F, mean value of 0.60 L/h) presented an inter-individual variability of 40 %, and an inter-occasion of 27 %. A modest but statistically significant decrease in CL/F was observed from Day 1 to Day 15 (-16.4, 95 % confidence interval of -8.5 to -27.2 %). However, trough pazopanib concentrations observed at Day 16 (24 h after the bevacizumab iv infusion) were not significantly higher than those observed just before the beginning of the bevacizumab iv infusion, suggesting that the pharmacokinetic change between Day 1 and Day 15 was not due to an interaction of bevacizumab. Overall, the mean observed concentrations at the maximum tolerated pazopanib dose (600 mg) at both Day 1 and Day 15 were higher than those observed at 800 mg once daily level (corresponding to the recommended dose when given alone) during the first-in-man phase 1 study of pazopanib in monochemotherapy. This first population pharmacokinetic analysis of pazopanib shows that inter-individual and inter-study pharmacokinetic variability emphasize the need for further evaluation of therapeutic drug monitoring for pazopanib as suggested for other tyrosine kinase inhibitors.