Population pharmacokinetics and CD20 binding dynamics for mosunetuzumab in relapsed/refractory B-cell non-Hodgkin lymphoma.

Mosunetuzumab (Mosun) is a CD20xCD3 T-cell engaging bispecific antibody that redirects T cells to eliminate malignant B cells. The approved step-up dose regimen of 1/2/60/30 mg IV is designed to mitigate cytokine release syndrome (CRS) and maximize efficacy in early cycles. A population pharmacokinetic (popPK) model was developed from 439 patients with relapsed/refractory B-Cell Non-Hodgkin lymphoma receiving Mosun IV monotherapy, including fixed dosing (0.05-2.8 mg IV every 3 weeks (q3w)) and Cycle 1 step-up dosing groups (0.4/1/2.8-1/2/60/30 mg IV q3w). Prior to Mosun treatment, ~50% of patients had residual levels of anti-CD20 drugs (e.g., rituximab or obinutuzumab) from prior treatment. CD20 receptor binding dynamics and rituximab/obinutuzumab PK were incorporated into the model to calculate the Mosun CD20 receptor occupancy percentage (RO%) over time. A two-compartment model with time-dependent clearance (CL) best described the data. The typical patient had an initial CL of 1.08 L/day, transitioning to a steady-state CL of 0.584 L/day. Statistically relevant covariates on PK parameters included body weight, albumin, sex, tumor burden, and baseline anti-CD20 drug concentration; no covariate was found to have a clinically relevant impact on exposure at the approved dose. Mosun CD20 RO% was highly variable, attributed to the large variability in residual baseline anti-CD20 drug concentration (median = 10 µg/mL). The 60 mg loading doses increased Mosun CD20 RO% in Cycle 1, providing efficacious exposures in the presence of the competing anti-CD20 drugs. PopPK model simulations, investigating Mosun dose delays, informed treatment resumption protocols to ensure CRS mitigation.

A Phase I Clinical Study Comparing the Pharmacokinetics, Safety, and Immunogenicity of GB221 Injection and Trastuzumab (Herceptin®) in Healthy Chinese Adults.

BACKGROUND AND OBJECTIVE: GB221 is a recombinant humanized anti-HER2 monoclonal antibody. The purpose of this study was to evaluate the pharmacokinetic, safety, and immunogenicity of GB221 in healthy Chinese adults in comparison to trastuzumab (Herceptin®). METHODS: In this randomized, double-blind, parallel-group phase I clinical trial, 88 subjects were randomized 1:1 to receive a single intravenous infusion (90-100 min) of GB221 or trastuzumab (6 mg/kg). The primary pharmacokinetic parameters-maximum observed serum concentration (Cmax), area under the serum concentration-time curve from zero to the last quantifiable concentration at time t (AUC0-t), and area under the serum concentration-time curve from time zero to infinity (AUC0-∞)-of GB221 and trastuzumab were compared to establish whether the 90% confidence interval (CI) attained the 80-125% bioequivalence standard. Safety and immunogenicity were also evaluated. RESULTS: The GB221 group (n = 43) and the trastuzumab group (n = 44) showed similar pharmacokinetic characteristics. The geometric mean ratios (90% CI) of Cmax, AUC0-t, and AUC0-∞ between the two groups were 107.53% (102.25-113.07%), 108.31% (103.57-113.26%), and 108.34% (103.57-113.33%), respectively. The incidence of treatment-emergent adverse events (TEAEs) was 83.7% (36/43) of the subjects in the GB221 group and 95.5% (42/44) of the subjects in the trastuzumab group. No subjects withdrew from the trial due to TEAEs, and there were no occurrences of serious adverse events. All subjects tested negative for antidrug antibodies (ADA). CONCLUSION: GB221 demonstrated similar pharmacokinetics to trastuzumab and comparable safety and immunogenicity in healthy Chinese adults.

Pharmacokinetic models for first-in-human dose selection of immune-activating products in oncology.

Pharmacokinetic (PK) models are increasingly submitted to the FDA to support first-in-human (FIH) dose selection of immune-oncology products. To examine whether a simple PK modeling (SPM) using clearance for scaling was acceptable for dose estimation, FIH(SPM) doses were computed and compared to doses that were safely administered to patients. We concluded that the SPM approach is acceptable in FIH dose estimation, but the variables should be carefully selected for CD3 constructs. For CD3 constructs, use of 60 kg BWh, a clearance exponent of 0.75, and a targeted plasma concentration based on relevant and/or sensitive activity assays was an acceptable approach for FIH dose selection; use of 0.85 as the scaling factor is questionable at this time as it resulted in a FIH dose that was too close to the AHD for one product (7%). Immune activating mAbs were not sensitive to changes in the clearance exponent (0.75-0.85) or body weight (60-70 kg). For PD-1/PD-L1 mAbs, using products' in vitro EC50 in the model resulted in suboptimal FIH doses and clinical data of closely related products informed FIH dose selection. PK models submitted by sponsors were diverse in methods, assumptions, and variables, and the resulting FIH doses were not always optimal.

Identification of ADME genes polymorphic variants linked to trastuzumab-induced cardiotoxicity in breast cancer patients: Case series of mono-institutional experience.

BACKGROUND: Long-term survival induced by anticancer treatments discloses emerging frailty among breast cancer (BC) survivors. Trastuzumab-induced cardiotoxicity (TIC) is reported in at least 5% of HER2+BC patients. However, TIC mechanism remains unclear and predictive genetic biomarkers are still lacking. Interaction between systemic inflammation, cytokine release and ADME genes in cancer patients might contribute to explain mechanisms underlying individual susceptibility to TIC and drug response variability. We present a single institution case series to investigate the potential role of genetic variants in ADME genes in HER2+BC patients TIC experienced. METHODS: We selected data related to 40 HER2+ BC patients undergone to DMET genotyping of ADME constitutive variant profiling, with the aim to prospectively explore their potential role in developing TIC. Only 3 patients ("case series"), who experienced TIC, were compared to 37 "control group" matched patients cardiotoxicity-sparing. All patients underwent to left ventricular ejection fraction (LVEF) evaluation at diagnosis and during anti-HER2 therapy. Each single probe was clustered to detect SNPs related to cardiotoxicity. RESULTS: In this retrospective analysis, our 3 cases were homogeneous in terms of clinical-pathological characteristics, trastuzumab-based treatment and LVEF decline. We identified 9 polymorphic variants in 8 ADME genes (UGT1A1, UGT1A6, UGT1A7, UGT2B15, SLC22A1, CYP3A5, ABCC4, CYP2D6) potentially associated with TIC. CONCLUSION: Real-world TIC incidence is higher compared to randomized clinical trials and biomarkers with potential predictive value aren't available. Our preliminary data, as proof of concept, could suggest a predictive role of pharmacogenomic approach in the identification of cardiotoxicity risk biomarkers for anti-HER2 treatment.

Extending the dosing intervals of nivolumab: model-based simulations in unselected cancer patients.

BACKGROUND: Reducing nivolumab dose intensity could increase patients' life quality and decrease the financial burden while maintaining efficacy. The aims of this study were to develop a population PK model of nivolumab based on data from unselected metastatic cancer patients and to simulate extended-interval regimens allowing to maintain minimal effective plasma concentrations (MEPC). METHODS: Concentration-time data (992 plasma nivolumab concentrations, 364 patients) were modeled using a two-compartment model with linear elimination clearance in Monolix software. Extended-interval regimens allowing to maintain steady-state trough concentrations (Cmin,ss) above the MEPC of 2.5 mg/L or 1.5 mg/L in >90% of patients were simulated. RESULTS: Increasing 3-times the dosing interval from 240 mg every two weeks (Q2W) to Q6W and 2-times from 480 mg Q4W to Q8W resulted in Cmin,ss above 2.5 mg/L in 95.8% and 95.4% of patients, respectively. 240 mg Q8W and 480 mg Q10W resulted in Cmin,ss above 1.5 mg/L in 91.0% and 91.8% of patients, respectively. Selection of a 240 mg Q6W regimen would decrease by 3-fold the annual treatment costs compared to standard regimen of 240 mg Q2W (from 78,744€ to 26,248€ in France). CONCLUSIONS: Clinical trials are warranted to confirm the non-inferiority of extended-interval compared to standard regimen.

Distinct uptake and elimination profiles for trastuzumab, human IgG, and biocytin-TMR in experimental HER2+ brain metastases of breast cancer.

BACKGROUND: The aim of this study is an improved understanding of drug distribution in brain metastases. Rather than single point snapshots, we analyzed the time course and route of drug/probe elimination (clearance), focusing on the intramural periarterial drainage (IPAD) pathway. METHODS: Mice with JIMT1-BR HER2+ experimental brain metastases were injected with biocytin-TMR and either trastuzumab or human IgG. Drugs/probes circulated for 5 min to 48 h, followed by perfusion. Brain sections were stained for human IgG, vascular basement membrane proteins laminin or collagen IV, and periarterial α-SMA. A machine learning algorithm was developed to identify metastases, metastatic microenvironment, and uninvolved brain in confocally scanned brain sections. Drug/probe intensity over time and total imaged drug exposure (iAUC) were calculated for 27,249 lesions and co-immunofluorescence with IPAD-vascular matrix analyzed in 11,668 metastases. RESULTS: In metastases, peak trastuzumab levels were 5-fold higher than human IgG but 4-fold less than biocytin-TMR. The elimination phase constituted 85-93% of total iAUC for all drugs/probes tested. For trastuzumab, total iAUC during uptake was similar to the small molecule drug probe biocytin-TMR, but slower trastuzumab elimination resulted in a 1.7-fold higher total iAUC. During elimination trastuzumab and IgG were preferentially enriched in the α-SMA+ periarterial vascular matrix, consistent with the IPAD clearance route; biocytin-TMR showed heterogeneous elimination pathways. CONCLUSIONS: Drug/probe elimination is an important component of drug development for brain metastases. We identified a prolonged elimination pathway for systemically administered antibodies through the periarterial vascular matrix that may contribute to the sustained presence and efficacy of large antibody therapeutics.

Nivolumab + relatlimab for the treatment of unresectable or metastatic melanoma.

INTRODUCTION: Though melanoma is one of the less common skin malignancies, it accounts for the majority of deaths due to cutaneous cancers. The recent progress and drug approvals in targeted treatment and immunotherapy revolutionized the outcome of patients with metastatic disease, and now is also changing the landscape of adjuvant treatment in melanoma. AREA COVERED: A combination of anti-PD-1 and anti-CTLA-4 (nivolumab with ipilimumab) has demonstrated superior outcomes in terms of progression-free survival (PFS) and overall survival with recent data confirming median survival exceeding six years. However, the use of this immunotherapy combination is limited in routine practice to approximately half of the patients due to high toxicity with the majority of patients at risk of severe adverse events. The current efforts are to determine how best to integrate combination immunotherapy in different clinical scenarios and limit these drugs' toxicity. That is why novel strategies in immunotherapy are needed and one of the examples of such novelty are anti-LAG-3 antibodies (lymphocyte-activation gene 3). LAG-3 inhibitor (relatlimab) in combination with nivolumab significantly improved PFS as compared to anti-PD-1 monotherapy in patients with previously untreated metastatic or unresectable melanoma. We describe the current status of combination of nivolumab+ relatlimab in the treatment of advanced melanoma patients based on the available data coming from pivotal clinical trials. EXPERT OPINION: The most important question to be answered is what would be the place of this novel combination in the treatment planning strategy.

Cellular 1H MR Relaxation Times in Healthy and Cancer Three-Dimensional (3D) Breast Cell Culture.

Noninvasive measurements of 1H Magnetic Resonance Imaging (MR) relaxation times in a three-dimensional (3D) cell culture construct are presented. Trastuzumab was used as a pharmacological component delivered to the cells in vitro. The purpose of this study was to evaluate the Trastuzumab delivery by relaxation times in 3D cell cultures. The bioreactor has been designed and used for 3D cell cultures. Four bioreactors were prepared, two with normal cells and two with breast cancer cells. The relaxation times of HTB-125 and CRL 2314 cell cultures were determined. An immunohistochemistry (IHC) test was performed before MRI measurements to confirm the amount of HER2 protein in the CRL-2314 cancer cells. The results showed that the relaxation time of CRL2314 cells is lower than normal HTB-125 cells in both cases, before and after treatment. An analysis of the results showed that 3D culture studies have potential in evaluating treatment efficacy using relaxation times measurements with a field of 1.5 Tesla. The use 1H MRI relaxation times allows for the visualization of cell viability in response to treatment.

A phase 1 safety and bioimaging trial of antibody DS-8895a against EphA2 in patients with advanced or metastatic EphA2 positive cancers.

Ephrin type-A 2 (EphA2) is a transmembrane receptor expressed in epithelial cancers. We report on a phase I dose escalation and biodistribution study of DS-8895a, an anti-EphA2 antibody, in patients with advanced EphA2 positive cancers. DS-8895a was administered at 1, 3, 10 or 20 mg/kg every 2 weeks to determine safety, pharmacokinetics and anti-tumor efficacy. All patients underwent 89Zr trace-labelled infusion of DS-8895a (89Zr-DS-8995a) positron emission tomography imaging to determine the biodistribution of DS-8895a, and correlate findings with EphA2 expression, receptor saturation and response. Nine patients were enrolled on study. Of patients enrolled, seven patients received at least one infusion of DS-8895a: four patients received 1 mg/kg dose (Cohort 1) and three patients received 3 mg/kg dose (Cohort 2). Median age was 67.0 years (range 52-81), majority male (71%), and median number of prior systemic therapies was three (range 0-8). The primary cancer diagnosis was colorectal cancer (two patients) and one patient each had gastric, head and neck, high-grade serous adenocarcinoma, lung, and pancreatic cancers. No dose-limiting toxicities or treatment-related adverse events reported. The best response for the patients in Cohort 1 was stable disease and in Cohort 2 was progressive disease. 89Zr-DS-8895a demonstrated no normal tissue uptake and specific low-grade uptake in most tumours. DS-8895a had limited therapeutic efficacy at doses evaluated and 89Zr-DS-8895a demonstrated low tumour uptake. The biodistribution data from this study were key in halting further development of DS-8895a, highlighting the importance of biodistribution studies in drug development. (Trial registration: ClinicalTrials.gov Identifier NCT02252211).

Eco-Friendly, Simple, Fast, and Sensitive UPLC-MS/MS Method for Determination of Pexidartinib in Plasma and Its Application to Metabolic Stability.

Pexidartinib is the first drug approved by the U.S. Food and Drug Administration specifically to treat the rare joint tumor tenosynovial giant cell tumor. In the current study, a validated, selective, and sensitive UPLC-MS/MS assay was developed for the quantitative determination of pexidartinib in plasma samples using gifitinib as an internal standard (IS). Pexidartinib and IS were extracted by liquid-liquid extraction using methyl tert-butyl ether and separated on an acquity BEH C18 column kept at 40 °C using a mobile phase of 0.1% formic acid in acetonitrile: 0.1% formic acid in de-ionized water (70:30). The flow rate was 0.25 mL/min. Multiple reaction monitoring (MRM) was operated in electrospray (ESI)-positive mode at the ion transition of 418.06 > 165.0 for the analyte and 447.09 > 128.0 for the IS. FDA guidance for bioanalytical method validation was followed in method validation. The linearity of the established UPLC-MS/MS assay ranged from 0.5 to 1000 ng/mL with r > 0.999 with a limit of quantitation of 0.5 ng/mL. Moreover, the metabolic stability of pexidartinib in liver microsomes was estimated.

Phase 1 study of anti-CD47 monoclonal antibody CC-90002 in patients with relapsed/refractory acute myeloid leukemia and high-risk myelodysplastic syndromes.

CC-90002 is an anti-CD47 antibody that inhibits CD47-SIRPα interaction and enables macrophage-mediated killing of tumor cells in hematological cancer cell lines. In this first clinical, phase 1, dose-escalation and -expansion study (CC-90002-AML-001; NCT02641002), we evaluated CC-90002 in patients with relapsed/refractory acute myeloid leukemia (AML) or high-risk myelodysplastic syndromes (MDS). CC-90002 was administered in escalating doses of 0.1-4.0 mg/kg, using a modified 3 + 3 design. Primary endpoints included dose-limiting toxicities (DLTs), non-tolerated dose (NTD), maximum tolerated dose (MTD), and recommended phase 2 dose. Secondary endpoints included preliminary efficacy, pharmacokinetics, and presence/frequency of anti-drug antibodies (ADAs). Between March 2016 and July 2018, 28 patients were enrolled (24 with AML and 4 with MDS) at 6 sites across the USA. As of July 18, 2018, all patients had discontinued, mainly due to death or progressive disease. The most common treatment-emergent adverse events were diarrhea (46.4%), thrombocytopenia (39.3%), febrile neutropenia (35.7%), and aspartate aminotransferase increase (35.7%). Four patients experienced DLTs (1 patient had grade 4 disseminated intravascular coagulation and grade 5 cerebral hemorrhage, 1 had grade 3 purpura, 1 had grade 4 congestive cardiac failure and grade 5 acute respiratory failure, and another had grade 5 sepsis). The NTD and MTD were not reached. No objective responses occurred. CC-90002 serum exposure was dose-dependent. ADAs were present across all doses, and the proportion of ADA-positive patients in cycle 1 increased over time. Despite no unexpected safety findings, the CC-90002-AML-001 study was discontinued in dose escalation for lack of monotherapy activity and evidence of ADAs. However, as other anti-CD47 agents in clinical trials are showing promising early results for AML and MDS, understanding preclinical and clinical differences between individual agents in this class will be of high importance.

Safety and pharmacokinetics of a new biosimilar trastuzumab (HL02): a Phase I bioequivalence study in healthy Chinese men.

OBJECTIVES: The study aimed to explore the bioequivalence of a proposed biosimilar HL02 vs. its reference products (US-trastuzumab) among healthy Chinese men. METHODS: In this study, nine healthy male subjects received single ascending doses of trastuzumab biosimilar (HL02, 2-8 mg/kg), and then a randomized, double-blind, two-arm, parallel study was conducted to investigate the PK similarity of HL02 (6 mg/kg) with that of US-trastuzumab as a reference drug. RESULTS: PK properties exhibited by HL02 (N = 55) were similar to those of US-trastuzumab (N = 52). The comparison of biosimilarity with US-trastuzumab showed that the 90% confidence intervals (CIs) of the ratios for Cmax, AUC0-t, and AUC0-∞ were within 80-125%. Nineteen subjects were positive for ADA and negative for NAb in both HL02 and US-trastuzumab groups. In total, 81.67% of subjects in HL02 and 78.95% in US-trastuzumab groups showed treatment-related mild or moderate adverse events, mild elevation of transaminase level being the most common adverse events (AE) recorded. CONCLUSIONS: The PK characteristics and immunogenicity exhibited by HL02 were similar to that of the reference product, US-trastuzumab. The safety profiles were similar in both the treatment groups with mild-moderate adverse effects.

Impacts of cachexia progression in addition to serum IgG and blood lymphocytes on serum nivolumab in advanced cancer patients.

PURPOSE: Serum nivolumab concentrations exhibit a large variation in cancer patients. Cancer cachexia inducing systemic inflammation promotes the elimination of endogenous proteins, while its association with serum nivolumab remains unclear. The present study aimed to evaluate the impacts of cachexia progression in addition to blood components on serum nivolumab in cancer patients. METHODS: Thirty-eight non-small-cell lung cancer or renal cell cancer patients receiving biweekly intravenous nivolumab were enrolled. Blood samples were collected just before dosing at the 7th administration of nivolumab or later. Serum nivolumab together with serum proteins, inflammatory markers, and peripheral blood leukocytes were determined. Cancer cachexia was classified using the Glasgow Prognostic Score (GPS). Immune-related adverse events (irAEs) were monitored during the study period. RESULTS: Cancer patients had a large variation in serum nivolumab concentrations (interquartile range, 12-21 µg/mL per mg/kg). The serum nivolumab concentration was positively correlated with serum albumin, while negatively associated with serum globulin and immunoglobulin G (IgG). A negative correlation was observed between serum nivolumab and blood lymphocytes. Regarding cachexia progression, the patients with GPS 2 had a higher serum interleukin-6 concentration and a lower serum nivolumab concentration than those with GPS 0 or 1. The GPS, serum IgG, and blood lymphocytes were identified as independent variables for serum nivolumab. The incidence of irAEs was not associated with the nivolumab dose or serum nivolumab. CONCLUSION: Cachexia progression had a negative impact on serum nivolumab in cancer patients. The interindividual variation in serum nivolumab was characterized by cachexia progression in addition to blood components.

Pharmacokinetic Simulation Analysis of Less Frequent Nivolumab and Pembrolizumab Dosing: Pharmacoeconomic Rationale for Dose Deescalation.

Nivolumab and pembrolizumab, anti-programmed cell death protein 1 monoclonal antibodies, have revolutionized oncology but are expensive. Using an interventional pharmacoeconomic approach, these drugs can be administered less often to reduce costs and increase patient convenience while maintaining efficacy. Both drugs are good candidates for less frequent dosing because of long half-lives and no evidence of a relationship of dose to efficacy. Established population pharmacokinetic models for both nivolumab and pembrolizumab were used to simulate profiles for multiple dosing regimens on 1000 randomly generated virtual patients. Simulations were initially performed on standard dose regimens to validate these in silico predictions. Next, simulations of nivolumab 0.3 mg/kg every 3 weeks revealed that >95% of patients maintained ≥1.5 µg/mL at steady state, which was inferred as the minimum effective concentration (MEC) for both drugs. Various alternative dosing regimens were simulated for both drugs to determine which regimen(s) can maintain this MEC in >95% of patients. Extended dosing regimens of nivolumab 240 mg every 4 weeks and 480 mg every 8 weeks along with pembrolizumab 200 mg every 6 weeks were simulated, showing that >95% of patients maintained MEC or greater. These simulations demonstrate the potential to reduce drug exposure by at least 50%, thus substantially reducing patient visits (as well as costs), while maintaining equivalent efficacy. These models provide the scientific justification for an ongoing prospective randomized clinical trial comparing standard interval fixed dosing with extended interval fixed dosing, and ultimately an efficacy-driven comparative trial.

Benefits and challenges of antibody drug conjugates as novel form of chemotherapy.

Antibody drug conjugates (ADCs) are an emerging therapeutic modality for targeted cancer treatment. They represent the unique amalgamation of chemotherapy and immunotherapy. ADCs comprise of monoclonal antibodies linked with drugs (payloads) through a chemical linker designed to deliver the cytotoxic moiety to the cancer cells. The present paper is a review of recent clinical advances of each component of ADCs (antibody/linker/payload) and how the individual component influences the activity of ADCs. The review discusses opportunities for improving ADCs efficiency and ways to have a better antibody-based molecular platform, which could substantially increase chemotherapy outcomes. This review casts an outlook on how ADCs enhancement in terms of their pharmacokinetics, therapeutic indexes and safety profiles can overcome the prevailing challenges like drug resistance in cancer treatment. A novel strategy of augmenting antibodies with nanoparticles anticipates a huge success in terms of targeted delivery of drugs in several diseases. Antibody conjugated nanoparticles (ACNPs) are a very promising strategy for the cutting-edge development of chemo/immunotherapies for efficient delivery of payloads at the targeted cancer cells. The avenues of a high drug to antibody ratio (DAR) owing to the selection of broad chemotherapy payloads, regulating drug release eliciting higher avidity of ACNPs over ADCs will be the modern immunotherapeutics. ACNPs carry immense potential to mark a paradigm shift in cancer chemotherapy that may be a substitute for ADCs.

Refined immunoRNases for the efficient targeting and selective killing of tumour cells: A novel strategy.

In order to overcome limitations of conventional cancer therapy methods, immunotoxins with the capability of target-specific action have been designed and evaluated pre-clinically, and some of them are in clinical studies. Targeting cancer cells via antibodies specific for tumour-associated surface proteins is a new biomedical approach that could provide the selectivity that is lacking in conventional cancer therapy methods such as radiotherapy and chemotherapy. A successful example of an approved immunotoxin is represented by immunoRNases. ImmunoRNases are fusion proteins in which the toxin has been replaced by a ribonuclease. Conjugation of RNase molecule to monoclonal antibody or antibody fragment was shown to enhance specific cell-killing by several orders of magnitude, both in vitro and in animal models. There are several RNases obtained from different mammalian cells that are expected to be less immunogenic and systemically toxic. In fact, RNases are pro-toxins which become toxic only upon their internalization in target cells mediated by the antibody moiety. The structure and large size of the antibody molecules assembled with the immunoRNases have always been a challenge in the application of immunoRNases as an antitoxin. To overcome this obstacle, we have offered a new strategy for the application of immunoRNases as a promising approach for upgrading immunoRNAses with maximum affinity and high stability in the cell, which can ultimately act as an effective large-scale cancer treatment. In this review, we introduce the optimized antibody-like molecules with small size, approximately 10 kD, which are presumed to significantly enhance RNase activity and be a suitable agent with the potential for anti-cancer functionality. In addition, we also discuss new molecular entities such as monobody, anticalin, nonobody and affilin as refined versions in the development of immunoRNases. These small molecules express their functionality with the suitable small size as well as with low immunogenicity in the cell, as a part of immunoRNases.

Tisotumab Vedotin: First Approval.

Tisotumab vedotin (Tivdak™) is an antibody-drug conjugate comprising a fully human monoclonal antibody specific for tissue factor (TF-011) conjugated to monomethyl auristatin E (MMAE) that has been engineered to target tissue factor expressing tumours. Based on the results of a phase II trial, tisotumab vedotin has been granted accelerated approval in the USA for the treatment of adult patients with recurrent or metastatic cervical cancer with disease progression on or after chemotherapy. This article summarizes the milestones in the development of tisotumab vedotin leading to this first approval.

Identification of neutralising pembrolizumab anti-drug antibodies in patients with melanoma.

Development of anti-drug antibodies (ADAs) can interfere with therapeutic monoclonal antibodies and may lead to drug neutralisation and clinical disease progression. Measurement of circulating drug levels and development of ADAs in the setting of anti-programmed cell death-1 agent pembrolizumab has not been well-studied. Enzyme-linked immunosorbent assays were used to measure pembrolizumab drug level and ADAs in 41 patients with melanoma at baseline, Time-point 1 (3 weeks) and Time-point 2 (21 weeks). Assay results were related to patient demographics and clinical outcome data at 6 months. The median pembrolizumab drug level at 3 weeks was 237 ng/µL and did not correlate with age, sex or body surface area.17/41 patients had an ADA detected at any timepoint, with the highest prevalence at Timepoint 1 (median concentration = 17 ng/µL). The presence of an ADA did not correlate with clinical progression at 6 months. 3/41 (7%) of patients displayed a falling pembrolizumab drug level and rising ADA titre between Timepoint 1 and 2 suggestive of a neutralising ADA. Pembrolizumab drug levels and ADAs can be readily measured. The rates of total and treatment-emergent ADAs may be higher in "real-word" settings than those previously reported. Larger studies are needed to determine effect of neutralising ADAs on long-term clinical outcome.

Analyze impact of tumor-associated kinetics on antibody delivery in solid tumors with a physiologically based pharmacokinetics/pharmacodynamics model.

Monoclonal antibody (mAb)-based drugs are critical anti-cancer therapies. Unfortunately, therapeutic efficacy can be compromised by spatially heterogeneous intratumoral Ab deposition. Binding-site barriers arising from Ab and tumor-associated kinetics often underlie this phenomenon. Quantitative insight into these issues may lead to more efficient drug delivery. Difficulties in addressing this issue include (1) lack of techniques to quantify critical kinetic events, (2) lack of a pharmacokinetic/pharmacodynamic (PK/PD) model to assess important parameters for specific tumor types, and (3) uncertainty or variability of critical kinetic factors even within a single tumor type. This study developed a mechanism-based PK/PD model to profile heterogeneous distribution of Ab within tumors and tested this model using real-life experimental data. Model simulations incorporating several uncertainties were used to determine how mAb and tumor-associated kinetics influence receptor occupancy. Simulations were also used to predict the potential impact of these findings in preclinical tumor models and human tumors. We found significant differences in tumor-associated kinetics between groups in which mAb therapy was effective versus groups in which it was ineffective. These kinetic differences included rates of tumor-associated antigen (TAA) degradation, TAA expression, apparent flow rates of interstitial fluid, and ratios of Ab-TAA complex internalization to TAA degradation. We found less significant differences in mAb kinetics, including rates of clearance or affinity for target antigens. In conclusion, our mechanism-based PK/PD model suggests that TAA-associated kinetic factors participate more significantly than those associated with the Ab in generating barriers to mAb delivery and distribution in tumors.

Targeting and pharmacology of an anti-IL13Rα2 antibody and antibody-drug conjugate in a melanoma xenograft model.

IL13Rα2 is a cell surface tumor antigen that is overexpressed in multiple tumor types. Here, we studied biodistribution and targeting potential of an anti-IL13Rα2 antibody (Ab) and anti-tumor activity of anti-IL13Rα2-antibody-drug conjugate (ADC). The anti-IL13Rα2 Ab was labeled with fluorophore AF680 or radioisotope 89Zr for in vivo tracking using fluorescence molecular tomography (FMT) or positron emission tomography (PET) imaging, respectively. Both imaging modalities showed that the tumor was the major uptake site for anti-IL13Rα2-Ab, with peak uptake of 5-8% ID and 10% ID/g as quantified from FMT and PET, respectively. Pharmacological in vivo competition with excess of unlabeled anti-IL13Rα2-Ab significantly reduced the tumor uptake, indicative of antigen-specific tumor accumulation. Further, FMT imaging demonstrated similar biodistribution and pharmacokinetic profiles of an auristatin-conjugated anti-IL13Rα2-ADC as compared to the parental Ab. Finally, the anti-IL13Rα2-ADC exhibited a dose-dependent anti-tumor effect on A375 xenografts, with 90% complete responders at a dose of 3 mg/kg. Taken together, both FMT and PET showed a favorable biodistribution profile for anti-IL13Rα2-Ab/ADC, along with antigen-specific tumor targeting and excellent therapeutic efficacy in the A375 xenograft model. This work shows the great potential of this anti-IL13Rα2-ADC as a targeted anti-cancer agent.