Current Perspectives on Ligand-Binding Assay Practices in the Quantification of Circulating Therapeutic Proteins for Biosimilar Biological Product Development.

Bioanalysis in biosimilar biological product development (BPD) plays a critical role in demonstrating pharmacokinetic (PK) similarity across products. The 2018 FDA Bioanalytical Method Validation guidance for industry provides general principles in the development, validation, and conduct of bioanalytical assays. Given that the PK similarity assessment in BPD programs involves two or more non-identical products, there are additional considerations for bioanalytical methods. Here in, we provide our perspectives on the definition of (1) a single bioanalytical method in the context of BPD in supporting a PK similarity study, (2) bioanalytical method comparability during accuracy and precision experiments to determine the potential bias difference prior to assessing other validation parameters, and (3) bioanalytical method validations that support PK similarity assessments.

Model-informed drug development approach supporting approval of the 4-week (Q4W) dosing schedule for nivolumab (Opdivo) across multiple indications: a regulatory perspective.

BACKGROUND: A nivolumab dosage regimen of 480 mg intravenously (i.v.) every 4 weeks (Q4W) was approved by FDA for the majority of the approved indications for nivolumab. METHODS: The proposed new dosage regimen was supported by pharmacokinetic modeling and simulation, dose/exposure-response relationships for efficacy and safety in the indicated patient populations, and the clinical safety data with the 480 mg Q4W dosage regimen. Pharmacokinetic exposures achieved with 480 mg Q4W were predicted for 4166 patients in 21 clinical studies with various types of solid and hematological tumors. Exposure-response analyses were conducted to predict 480 mg Q4W safety and efficacy across all FDA-approved indications for nivolumab. RESULTS: For the overall population, the geometric mean exposure achieved with 480 mg i.v. Q4W was 5.2% higher for steady state Cavg and 15.6% lower for Ctrough than those with 3 mg/kg i.v. Q2W, the approved dosage regimen. The simulated concentration-time course achieved with 480 mg Q4W regimen was below the median concentration achieved with 10 mg/kg i.v. Q2W that was also studied in clinical trials. The predicted probability of adverse events was similar between 480 mg Q4W and that observed with the 3 mg/kg Q2W regimen. Efficacy results were found to be similar between Q2W and Q3W dosage regimens in patients with renal cell carcinoma. The predicted efficacy for each indication suggested that the efficacy with 480 mg Q4W is unlikely to be compromised compared with that observed with 3 mg/kg Q2W. CONCLUSIONS: The model-informed analyses of predicted exposure, efficacy and safety based on data from extensive clinical experience with nivolumab suggest that the benefit-risk profile of 480 mg Q4W regimen is comparable to the approved 3 mg/kg Q2W regimen, thus providing the regulatory basis for the approval of 480 mg Q4W regimen in the absence of clinical efficacy data with this new dosage regimen.

Association of time-varying clearance of nivolumab with disease dynamics and its implications on exposure response analysis.

Nivolumab is a human monoclonal antibody that blocks the interaction between PD-1 programmed death-1 (PD-1) and its ligands, PD-L1 and PD-L2. Nivolumab demonstrated efficacy in clinical trials for various types of cancer. A time-varying clearance was identified for nivolumab. We show that the change of clearance over time is associated with the post-treatment effects: clearance decreases when disease status improves. This interaction between posttreatment effects and drug exposure may lead to a biased steep estimate of the exposure-response (E-R) relationship for efficacy. Under this scenario, simulations were performed to develop a proposed methodology to assess the causal effect of drug exposure upon clinical response. Data from nivolumab trials were subsequently used to verify the proposed methodology for E-R analysis. The results showed that E-R analysis results based on pharmacokinetic (PK) metrics derived from the first dose are more consistent with the true E-R or dose-response relationship than the steady-state PK metrics.

Toward greater insights on pharmacokinetics and exposure-response relationships for therapeutic biologics in oncology drug development.

There has been increased interest in optimizing dosing regimens for oncology products over the past decade. Investigations to refine dosing regimens often occur after new drug approval. There is growing focus on the use of exposure-response (ER) approaches to identify optimal dosing regimens for therapeutic biologics. Herein, we describe several recent observations that have informed our thinking on the use of ER analyses in the dose regimen optimization of therapeutic biologics developed to treat cancer.

An unusual rash for Royal: a case series.

Eight patients, whilst on exercise in Albania, presented with a blistering, erythematous and itchy rash, consistent with caustic burns, after living in dense vegetation for a few days. All patients were found to have been living and operating under fig trees and had come into contact with the sap of Ficus carica, which on exposure to ultraviolet A (UVA) radiation, can cause a process of phytophotodermatitis leading to a blistering rash.

Evaluating sexual function in women after radical cystectomy as treatment for bladder cancer.

OBJECTIVE: Sexual function remains a relatively unexplored field within urology, especially for female patients who have undergone radical cystectomy (RC). The aim of this study was to shed light on this area. MATERIALS AND METHODS: The Female Sexual Function Index (FSFI) questionnaire and other selective questions regarding sexual function were sent to 71 women who had undergone RC and were alive 1 year postsurgery. Forty-one completed questionnaires were returned and analysed using simple descriptive statistical analysis, owing to the small sample size. RESULTS: The median age of the patients was 67 years (range 39-91 years). Seventy-eight per cent reported being sexually active before surgery and 37% post-surgery. The median FSFI score postsurgery was 4.8 (range 1.2-32). The highest FSFI score was seen in the category of satisfaction, which consists of questions regarding closeness with partner, sexual relationship and overall sex life. Lowest FSFI scores were seen for lubrication, orgasm and pain. Twenty-seven per cent of patients wanted more information on the impact RC would have on their sex lives and many asked for information for their partners. CONCLUSION: Despite being based on a limited number of patients, this study indicates a need for improvement within this field. Most patients scored below 26 on the FSFI questionnaire, the cut-off for sexual dysfunction. However, many reported being satisfied overall. Thus, the physician's main goal is to identify patients in need of more information and guidance before and after surgery.

Unusual cause of recurrent fever after travel in South America.

Fever in returning travelers is a common problem and usually the diagnosis is made within a few days or the traveler recovers. We present two travelers who presented with fever two weeks after returning from a six week vacation in South America. Over the following 18 months they presented with short attacks of fever, elevated CRP and leukocytosis and the program for investigation became more and more elaborate. A curious and key feature was, that they were completely synchronous both developing symptoms within an hour and presentation with the same laboratory findings of leukocytosis and elevated CRP. Extensive and repeated tests were performed, at our facility and abroad. After a year it was discovered that the uses of aroma oils were associated with the symptoms. No similar case has been found to be reported previously. These cases emphasize that natural products are not inherently safe. The investigational program was build up over time as new attacks continued to occur and suggestions from different centers which were consulted were followed up. The number of tests performed at different laboratories took an extensive amount of time. These cases emphasize that a panel of analysis in returning travelers in which no clear diagnosis is found should be developed.

Exposure-response relationship of T-DM1: insight into dose optimization for patients with HER2-positive metastatic breast cancer.

Exposure-response (E-R) analyses for ado-trastuzumab emtansine (T-DM1, Kadcyla) were performed using data from a randomized, active control (lapatinib plus capecitabine) trial in patients with human epidermal growth factor 2-positive metastatic breast cancer. Kaplan-Meier survival analyses stratified by T-DM1 trough concentration on day 21 of cycle 1 (Cmin,C1D21) were performed for overall survival (OS) and progression-free survival (PFS). E-R analyses indicated that after adjusting for baseline risk factors, higher T-DM1 exposure is associated with improved efficacy. T-DM1-treated patients with Cmin,C1D21 lower than the median value had values of OS and PFS comparable to those of the active control arm. The percentage of patients who received T-DM1 dose adjustments was similar across the exposure range and was lower than that of the active control arm. Our findings suggest that there may be an opportunity to optimize Kadcyla dose in the patient subgroup with low T-DM1 exposure for improved efficacy with acceptable tolerability.

Can adenocarcinoma in situ of the uterine cervix be treated safely by conisation in combination with endocervical curettage?

OBJECTIVE: To evaluate the prognostic value of endocervical curettage (ECC) after conisation in patients treated for adenocarcinoma in situ (AIS) of the uterine cervix. MATERIALS AND METHODS: Patients with AIS diagnosed between 1990 and 2010 and with a minimum of 1.5 years of follow-up were retrospectively identified using computerised clinical files. RESULTS: The authors identified 195 patients (median age 32 years) with a median follow-up of 6.4 years. ECC was performed in 165 patients. In 144 (87%) the initial ECC was normal. In 129 no recurrence was observed during follow-up (90%). A positive ECC was observed in 21. Thirteen patients had hysterectomies; six hysterectomies were normal. Eight patients treated conservatively developed no recurrent disease. Two patients with a positive ECC did not have a hysterectomy and developed recurrent disease. In patients with affected margins, 17% developed recurrent disease. CONCLUSION: ECC performed during initial conisation is a prognostic tool for the treatment ofAIS. Close follow-up is recommended in patients treated conservatively.

The normal mammary microenvironment suppresses the tumorigenic phenotype of mouse mammary tumor virus-neu-transformed mammary tumor cells.

The microenvironment of the mammary gland has been shown to exert a deterministic control over cells from different normal organs during murine mammary gland regeneration in transplantation studies. When mouse mammary tumor virus (MMTV)-neu-induced tumor cells were mixed with normal mammary epithelial cells (MECs) in a dilution series and inoculated into epithelium-free mammary fat pads, they were redirected to non-carcinogenic cell fates by interaction with untransformed MECs during regenerative growth. In the presence of non-transformed MECs (50:1), tumor cells interacted with MECs to generate functional chimeric outgrowths. When injected alone, tumor cells invariably produced tumors. Here, the normal microenvironment redirects MMTV-neu-transformed tumorigenic cells to participate in the regeneration of a normal, functional mammary gland. In addition, the redirected tumor cells show the capacity to differentiate into normal mammary cell types, including luminal, myoepithelial and secretory. The results indicate that signals emanating from a normal mammary microenvironment, comprised of stromal, epithelial and host-mediated signals, combine to suppress the cancer phenotype during glandular regeneration. Clarification of these signals offers improved therapeutic possibilities for the control of mammary cancer growth.

Applications of physiologically based pharmacokinetic (PBPK) modeling and simulation during regulatory review.

Physiologically based pharmacokinetic (PBPK) modeling and simulation is a tool that can help predict the pharmacokinetics of drugs in humans and evaluate the effects of intrinsic (e.g., organ dysfunction, age, genetics) and extrinsic (e.g., drug-drug interactions) factors, alone or in combinations, on drug exposure. The use of this tool is increasing at all stages of the drug development process. This report reviews recent instances of the use of PBPK in decision-making during regulatory review. The examples are based on Center for Drug Evaluation and Research reviews of several submissions for investigational new drugs (INDs) and new drug applications (NDAs) received between July 2008 and June 2010. The use of PBPK modeling and simulation facilitated the following types of decisions: the need to conduct specific clinical pharmacology studies, specific study designs, and appropriate labeling language. The report also discusses the challenges encountered when PBPK modeling and simulation were used in these cases and recommends approaches to facilitating full utilization of this tool.

Elucidation of relationship between tumor size and survival in non-small-cell lung cancer patients can aid early decision making in clinical drug development.

Four non-small-cell lung cancer (NSCLC) registration trials were utilized to develop models linking survival to risk factors and changes in tumor size during treatment. The purpose was to leverage existing quantitative knowledge to facilitate future development of anti-NSCLC drugs. Eleven risk factors were screened using a Cox model. A mixed exponential decay and linear growth model was utilized for modeling tumor size. Survival times were described in a parametric model. Eastern Cooperative Oncology Group (ECOG) score and baseline tumor size were consistent prognostic factors of survival. Tumor size was well described by the mixed model. The parametric survival model includes ECOG score, baseline tumor size, and week 8 tumor size change as predictors of survival duration. The change in tumor size at week 8 allows early assessment of the activity of an experimental regimen. The survival model and the tumor model will be beneficial for early screening of candidate drugs, simulating NSCLC trials, and optimizing trial designs.

Mixed state discrimination using optimal control.

We present theory and experiment for the task of discriminating two nonorthogonal states, given multiple copies. We implement several local measurement schemes, on both pure states and states mixed by depolarizing noise. We find that schemes which are optimal (or have optimal scaling) without noise perform worse with noise than simply repeating the optimal single-copy measurement. Applying optimal control theory, we derive the globally optimal local measurement strategy, which outperforms all other local schemes, and experimentally implement it for various levels of noise.

Recognition and management of depression in a substance use disorder treatment population.

This study examines the association between depressive symptomatology and return to substance use among a sample of 126 veterans consecutively admitted to treatment at a VA intensive outpatient program for substance use disorders. Controlling for numerous demographic and health-related covariates, depressive symptomatology measured at treatment exit with a Beck Depression Inventory (BDI) was significantly predictive of substance use at three-months post-treatment (p < .05). Analysis with a recoded BDI showed that the moderately-to-severely symptomatic (BDI = 20+) were 4.1 times more likely to have returned to substance use than those with a BDI score of under 20.

A methodology for probabilistic predictions of regional climate change from perturbed physics ensembles.

A methodology is described for probabilistic predictions of future climate. This is based on a set of ensemble simulations of equilibrium and time-dependent changes, carried out by perturbing poorly constrained parameters controlling key physical and biogeochemical processes in the HadCM3 coupled ocean-atmosphere global climate model. These (ongoing) experiments allow quantification of the effects of earth system modelling uncertainties and internal climate variability on feedbacks likely to exert a significant influence on twenty-first century climate at large regional scales. A further ensemble of regional climate simulations at 25km resolution is being produced for Europe, allowing the specification of probabilistic predictions at spatial scales required for studies of climate impacts. The ensemble simulations are processed using a set of statistical procedures, the centrepiece of which is a Bayesian statistical framework designed for use with complex but imperfect models. This supports the generation of probabilities constrained by a wide range of observational metrics, and also by expert-specified prior distributions defining the model parameter space. The Bayesian framework also accounts for additional uncertainty introduced by structural modelling errors, which are estimated using our ensembles to predict the results of alternative climate models containing different structural assumptions. This facilitates the generation of probabilistic predictions combining information from perturbed physics and multi-model ensemble simulations. The methodology makes extensive use of emulation and scaling techniques trained on climate model results. These are used to sample the equilibrium response to doubled carbon dioxide at any required point in the parameter space of surface and atmospheric processes, to sample time-dependent changes by combining this information with ensembles sampling uncertainties in the transient response of a wider set of earth system processes, and to sample changes at local scales. The methodology is necessarily dependent on a number of expert choices, which are highlighted throughout the paper.

Structure-function relationships of insulin-like growth factor binding protein 6 (IGFBP-6) and its chimeras.

Insulin-like growth factor binding protein 6 (IGFBP-6) is a high-affinity IGFBP with substantially greater affinity for insulin-like growth factor-II (IGF-II) than IGF-I. IGFBP-6(3) is a chimera which has a 20 amino acidC -terminal portion of IGFBP-6 switched with the homologous area of IGFBP-3, P3. Unlike IGFBP-4(3), in which the P3 region was exchanged for the homologous region of IGFBP-4 (P4), IGFBP-6(3) does not bind to endothelial cells. Double mutations were made with the P3 region exchanged as well as a second area differing from IGFBP-3 to form IGFBP-6(3)A and IGFBP-6(3)B, by replacing this area with the homologous region of IGFBP-3. Neither [(125)I]IGFBP-6(3)A nor IGFBP-6(3)B specifically bound to endothelial cells. However, each double mutant competed for [(125)I]IGFBP-3 binding to cultured cells. In the perfused heart, transendothelial transport of IGFBP-6 and IGFBP-6(3) was only 25% of similar transendothelial transport of perfused IGFBP-3. We conclude that chimeras of IGFBP-6 and IGFBP-3(6) clearly differ from IGFBP-4(3) in their ability to bind specifically to endothelial cells and in their capacity to undergo transendothelial transportation in the perfused heart.

IGFBP-3 binding to endothelial cells inhibits plasmin and thrombin proteolysis.

Insulin-like growth factor-binding protein (IGFBP)-3 contains a highly basic COOH-terminal heparin-binding region, the P3 region, which is thought to be important in the binding of IGFBP-3 to endothelial cells. IGFBP-3 and IGFBP-4, and their chimeras IGFBP-3(4) and IGFBP-4(3), were treated with plasmin and with thrombin, proteases known to cleave IGFBP-3. IGFBP-3 was highly susceptible to plasmin, whereas IGFBP-4 was less so. Substitution of the P3 region for the P4 region in IGFBP-4 (IGFBP-4(3)) increased the ability of the protease to digest IGFBP-4(3); substitution of the P4 region for the P3 region in IGFBP-3 (IGFBP-3(4)) decreased the digestion of IGFBP-3(4). When 125I-labeled IGFBP-3 or 125I-IGFBP-4(3) was first bound to vascular endothelial cells, subsequent proteolysis by either plasmin or thrombin was substantially inhibited. Proteolysis of 125I-IGFBP-3(4) was not inhibited in the presence of endothelial cells. The P3 peptide was cleaved by plasmin but not by thrombin. We conclude that the P3 region is central to proteolysis of IGFBP-3 by plasmin and thrombin, processes which were inhibited by association of IGFBP-3 with endothelial cells.