The development of mechanism-based, multiscale pharmacokinetic–pharmacodynamic (PK-PD) models for chimeric antigen receptor (CAR)-T cells is needed to enable investigation of in vitro and in vivo correlation of CAR-T cell responses and to facilitate preclinical-to-clinical translation. Toward this goal, we first developed a cell-level in vitro PD model that quantitatively characterized CAR-T cell-induced target cell depletion, CAR-T cell expansion and cytokine release. The model accounted for key drug-specific (CAR-affinity, CAR-densities) and system-specific (antigen densities, E:T ratios) variables and was able to characterize comprehensive in vitro datasets from multiple affinity variants of anti-EGFR and anti-HER2 CAR-T cells. Next, a physiologically based PK (PBPK) model was developed to simultaneously characterize the biodistribution of untransduced T-cells, anti-EGFR CAR-T and anti-CD19 CAR-T cells in xenograft -mouse models. The proposed model accounted for the engagement of CAR-T cells with tumor cells at the site of action. Finally, an integrated PBPK-PD relationship was established to simultaneously characterize expansion of CAR-T cells and tumor growth inhibition (TGI) in xenograft mouse model, using datasets from anti-BCMA, anti-HER2, anti-CD19 and anti-EGFR CAR-T cells. Model simulations provided potential mechanistic insights toward the commonly observed multiphasic PK profile (i.e., rapid distribution, expansion, contraction and persistence) of CAR-T cells in the clinic. Model simulations suggested that CAR-T cells may have a steep dose-exposure relationship, and the apparent Cmax upon CAR-T cell expansion in blood may be more sensitive to patient tumor-burden than CAR-T dose levels. Global sensitivity analysis described the effect of other drug-specific parameters toward CAR-T cell expansion and TGI. The proposed modeling framework will be further examined with the clinical PK and PD data, and the learnings can be used to inform design and development of future CAR-T therapies.

Chimeric antigen receptor (CAR)‐T cell therapy has achieved considerable success in treating B‐cell hematologic malignancies. However, the challenges of extending CAR‐T therapy to other tumor types, particularly solid tumors, remain appreciable. There are substantial variabilities in CAR‐T cellular kinetics across CAR‐designs, CAR‐T products, dosing regimens, patient responses, disease types, tumor burdens, and lymphodepletion conditions. As a “living drug,” CAR‐T cellular kinetics typically exhibit four distinct phases: distribution, expansion, contraction, and persistence. The cellular kinetics of CAR‐T may correlate with patient responses, but which factors determine CAR‐T cellular kinetics remain poorly defined. Herein, we developed a cellular kinetic model to retrospectively characterize CAR‐T kinetics in 217 patients from 7 trials and compared CAR‐T kinetics across response status, patient populations, and tumor types. Based on our analysis results, CAR‐T cells exhibited a significantly higher cell proliferation rate and capacity but a lower contraction rate in patients who responded to treatment. CAR‐T cells proliferate to a higher degree in hematologic malignancies than in solid tumors. Within the assessed dose ranges (107‒109 cells), CAR‐T doses were weakly correlated with CAR‐T cellular kinetics and patient response status. In conclusion, the developed CAR‐T cellular kinetic model adequately characterized the multiphasic CAR‐T cellular kinetics and supported systematic evaluations of the potential influencing factors, which can have significant implications for the development of more effective CAR‐T therapies.

Cocaine blocks dopamine uptake via dopamine transporter (DAT) on plasma membrane of neuron cells and, as a result, produces the high and induces DAT trafficking to plasma membrane which contributes to the drug seeking or craving. In this study, we first examined the dose dependence of cocaine-induced DAT trafficking and hyperactivity in rats, demonstrating that cocaine at an intraperitoneal dose of 10 mg/kg or higher led to redistribution of most DAT to the plasma membrane while inducing significant hyperactivity in rats. However, administration of 5-mg/kg cocaine (ip) did not significantly induce DAT trafficking or hyperactivity in rats. So the threshold (intraperitoneal) dose of cocaine that can significantly induce DAT trafficking or hyperactivity should be between 5 and 10 mg/kg. These data suggest that when a cocaine dose is high enough to induce significant hyperactivity, it can also significantly induce DAT trafficking to the plasma membrane. Further, the threshold brain cocaine concentration required to induce significant hyperactivity and DAT trafficking was estimated to be $2.0 ± 0.8 μg/g. Particularly, for treatment of cocaine abuse, previous studies demonstrated that an exogenous cocainemetabolizing enzyme, for example, CocH3-Fc(M3), can effectively block cocaineinduced hyperactivity. However, it was unknown whether an enzyme could also effectively block cocaine-induced DAT trafficking to the plasma membrane. This study demonstrates, for the first time, that the enzyme is also capable of effectively blocking cocaine from reaching the brain even with a lethal dose of 60-mg/kg cocaine (ip) and, thus, powerfully preventing cocaine-induced physiological effects such as the hyperactivity and DAT trafficking.

Human mPGES-1 is recognized as a promising target for next generation of anti-inflammatory drugs without the side effects of currently available anti-inflammatory drugs, and various inhibitors have been reported in the literature. However, none of the reported potent inhibitors of human mPGES-1 has shown to be also a potent inhibitor of mouse or rat mPGES-1, which prevents using the well-established mouse/rat models of inflammation-related diseases for preclinical studies. Hence, despite of extensive efforts to design and discover various human mPGES-1 inhibitors, the promise of mPGES-1 as a target for the next generation of anti-inflammatory drugs has never been demonstrated in any wild-type mouse/rat model using an mPGES-1 inhibitor. Here we report discovery of a novel type of selective mPGES-1 inhibitors potent for both human and mouse mPGES-1 enzymes through structure-based rational design. Based on in vivo studies using wild-type mice, the lead compound is indeed non-toxic, orally bioavailable, and more potent in decreasing the PGE 2 (an inflammatory marker) levels compared to the currently available drug celecoxib. This is the first demonstration in wild-type mice that mPGES-1 is truly a promising target for the next generation of anti-inflammatory drugs.As the principal pro-inflammatory prostanoid, prostaglandin E2 (PGE 2 ) serves as a mediator of pain and fever in inflammatory reactions in a number of inflammation-related diseases 1 , such as chronic pains, cardiovascular diseases, neurodegenerative diseases, and cancers 2-4 . The biosynthesis 5 of PGE 2 starts from arachidonic acid (AA). Cyclooxygenase (COX)-1 or COX-2 converts AA to prostaglandin H2 (PGH 2 ) 5 , and prostaglandin E synthase (PGES) transforms PGH 2 to PGE 2 6 . The first generation of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin used to treat pain and reduce fever or inflammation, inhibit both COX-1 and COX-2 without selectivity, and the second generation of NSAIDs, including celecoxib (Celebrex), rofecoxib (Vioxx) and valdecoxib (Bextra), selectively inhibit COX-2. The COX-2 specific inhibitors still have a number of serious side effects, such as increasing the risk of fatal heart attack or stroke and causing stomach or intestinal bleeding. The serious side effects led to withdrawal of rofecoxib and valdecoxib, although celecoxib still remains in clinical use. The serious side effects are due to the fact that the synthesis of all physiologically needed prostaglandins downstream of PGH 2 are inhibited by the action of the COX-1/2 inhibitors. For example, blocking the production of prostaglandin-I 2 (PGI 2 ) will cause significant cardiovascular problems 7 .Microsomal PGES-1 (mPGES-1), an inducible enzyme, is a more promising, ideal target for anti-inflammatory drugs, because the mPGES-1 inhibition will only block the PGE 2 production without affecting the production of

Despite tremendous success of chimeric antigen receptor (CAR) T cell therapy in clinical oncology, the dose-exposure-response relationship of CART cells in patients is poorly understood. Moreover, the key drug-and system-specific determinants leading to favourable clinical outcomes are also unknown. Here, we have developed a multiscale mechanistic PK-PD model for anti-BCMA (bb2121) CART cell therapy to characterize 1) in vitro target cell killing in multiple BCMA expressing tumor cell lines at varying E:T ratios, 2) preclinical in vivo tumor growth inhibition (TGI) and blood CART cell expansion in xenograft mice, and 3) clinical PK and PD biomarkers in multiple myeloma (MM) patients. Our translational PK-PD relationship was able to effectively describe the commonly observed multiphasic CART cell PK profile in clinic, consisting of rapid distribution, expansion, contraction and persistent phases, as well as accounted for the categorical individual responses in multiple myeloma to effectively calculate progression-free survival rates. Preclinical and clinical data analysis revealed comparable parameter estimates pertaining to CART cell functionality and suggested that patient baseline tumor burden could be more sensitive than dose levels towards overall extent of exposure (Cmax) after CART cell infusion. Virtual patient simulations also suggested a very steep dose-exposure-response relationship with CART cell therapy and indicated presence of a 'threshold' dose, beyond which a flat dose-response curve could be observed. Our simulations were concordant with multiple clinical observations discussed within this paper. Moving forward, this framework could be leveraged a priori, to explore multiple infusions and support preclinical/clinical development of future CART cell therapies.