Optimization of drug regimen in chemotherapy based on semi-mechanistic model for myelosuppression

Suppression of poised oncogenes by ZMYND8 promotes chemo-sensitization

The major challenge in chemotherapy lies in the gain of therapeutic resistance properties of cancer cells. The relatively small fraction of chemo-resistant cancer cells outgrows and are responsible for tumor relapse, with acquired invasiveness and stemness. We demonstrate that zinc-finger MYND type-8 (ZMYND8), a putative chromatin reader, suppresses stemness, drug resistance, and tumor-promoting genes, which are hallmarks of cancer. Reinstating ZMYND8 suppresses chemotherapeutic drug doxorubicin-induced tumorigenic potential (at a sublethal dose) and drug resistance, thereby resetting the transcriptional program of cells to the epithelial state. The ability of ZMYND8 to chemo-sensitize doxorubicin-treated metastatic breast cancer cells by downregulating tumor-associated genes was further confirmed by transcriptome analysis. Interestingly, we observed that ZMYND8 overexpression in doxorubicin-treated cells stimulated those involved in a good prognosis in breast cancer. Consistently, sensitizing the cancer cells with ZMYND8 followed by doxorubicin treatment led to tumor regression in vivo and revert back the phenotypes associated with drug resistance and stemness. Intriguingly, ZMYND8 modulates the bivalent or poised oncogenes through its association with KDM5C and EZH2, thereby chemo-sensitizing the cells to chemotherapy for better disease-free survival. Collectively, our findings indicate that poised chromatin is instrumental for the acquisition of chemo-resistance by cancer cells and propose ZMYND8 as a suitable epigenetic tool that can re-sensitize the chemo-refractory breast carcinoma.

Chimeric antigen receptor T cell therapy and nephrotoxicity: From diagnosis to treatment strategies

Chimeric antigen receptor T (CAR-T) cell therapy is a breakthrough in cancer treatment. With the widespread use of this therapy, increasing evidence is available that CAR-T cell therapy is associated with acute kidney injury (AKI). Nephrologists need to understand the potential nephrotoxicity arising from CAR-T cell therapy. Determining the cause of AKI is a key factor of clinical management. This review focuses on the clinical use of CAR-T cell therapy and the cause and outcomes of nephrotoxicity with its use. We also provide clinical suggestions for clinicians towards both better diagnosis and management of AKI in those receiving CAR-T cell therapy.

Optimising Hydrogel Release Profiles for Viro-Immunotherapy Using Oncolytic Adenovirus Expressing IL-12 and GM-CSF with Immature Dendritic Cells

Sustained-release delivery systems, such as hydrogels, significantly improve cancer therapies by extending the treatment efficacy and avoiding excess wash-out. Combined virotherapy and immunotherapy (viro-immunotherapy) is naturally improved by these sustained-release systems, as it relies on the continual stimulation of the antitumour immune response. In this article, we consider a previously developed viro-immunotherapy treatment where oncolytic viruses that are genetically engineered to infect and lyse cancer cells are loaded onto hydrogels with immature dendritic cells (DCs). The time-dependent release of virus and immune cells results in a prolonged cancer cell killing from both the virus and activated immune cells. Although effective, a major challenge is optimising the release profile of the virus and immature DCs from the gel so as to obtain a minimum tumour size. Using a system of ordinary differential equations calibrated to experimental results, we undertake a novel numerical investigation of different gel-release profiles to determine the optimal release profile for this viro-immunotherapy. Using a data-calibrated mathematical model, we show that if the virus is released rapidly within the first few days and the DCs are released for two weeks, the tumour burden can be significantly decreased. We then find the true optimal gel-release kinetics using a genetic algorithm and suggest that complex profiles present unnecessary risk and that a simple linear-release model is optimal. In this work, insight is provided into a fundamental problem in the growing field of sustained-delivery systems using mathematical modelling and analysis.

Optimization of clinical dosing schedule to manage neutropenia: learnings from semi-mechanistic modeling simulation approach

Neutropenia is a common side-effect of oncology drugs. We aimed to study the impact of exposure and dosing schedule on neutropenia to guide selection of dosing schedules that minimize neutropenia potential while maintaining the desired minimum concentration (C_min) required for target engagement. Dose, frequency and PK parameters were chosen for five hypothetical drugs of various half-lives to (1) achieve same exposure with continuous dosing and evaluate impact of 4 intermittent dosing schedules; and (2) achieve same nadir for continuous and intermittent dosing and evaluate impact on % time above C_min, a surrogate assumed to indicate target engagement. Absolute neutrophil count (ANC) profiles were simulated using Friberg model, a widely used semi-mechanistic myelosuppression model, assuming drug concentration directly reduce the proliferation rate of stem cells and progenitor cells in proliferation compartment. The correlations between different PK measures and neutropenia metrics were explored. In (1), when the same daily dose was used, intermittent schedules offered better management of ANC nadir. The reduced average drug exposure with intermittent dosing led to lower% time above C_min. In (2), when the dose was adjusted to achieve the same nadir, drugs with moderate half-life (8-48 h) showed similar % time above C_min regardless of schedule, while continuous dosing was better for a short half-life (4 h). Area under the concentration curve (AUC) was highly correlated with neutropenia. In summary, continuous dosing, with the dose selected correctly, is most effective to maintain % time above C_min while providing similar tolerability as intermittent dosing with a higher dose. But dose interruptions could be required to manage individual toxicities. Intermittent schedules, on the other hand, allow recovery of ANC, enabling more orderly schedules.

Optimization of Cancer Treatment in the Frequency Domain

Thorough exploration of alternative dosing frequencies is often not performed in conventional pharmacometrics approaches. Quantitative systems pharmacology (QSP) can provide novel insights into optimal dosing regimen and drug behaviors which could add a new dimension to the design of novel treatments. However, methods for such an approach are currently lacking. Recently, we illustrated the utility of frequency-domain response analysis (FdRA), an analytical method used in control engineering, using several generic pharmacokinetic-pharmacodynamic case studies. While FdRA is not applicable to models harboring ever increasing variables such as those describing tumor growth, studying such models in the frequency domain provides valuable insight into optimal dosing frequencies. Through the analysis of three distinct tumor growth models (cell cycle-specific, metronomic, and acquired resistance), we demonstrate the application of a simulation-based analysis in the frequency domain to optimize cancer treatments. We study the response of tumor growth to dosing frequencies while simultaneously examining treatment safety, and found for all three models that above a certain dosing frequency, tumor size is insensitive to an increase in dosing frequency, e.g., for the cell cycle-specific model, one dose per 3 days, and an hourly dose yield the same reduction of tumor size to 3% of the initial size after 1 year of treatment. Additionally, we explore the effect of drug elimination rate changes on the tumor growth response. In summary, we show that the frequency-domain view of three models of tumor growth dynamics can help in optimizing drug dosing regimen to improve treatment success.

Compatibility effects of ginseng and Ligustrum lucidum Ait herb pair on hematopoietic recovery in mice with cyclophosphamide-induced myelosuppression and its material basis

Background

Ginseng (G) and Ligustrum lucidum Ait (LLA) are core traditional Chinese medicines in treating myelosuppression formula. The present study was designed to profile effect of G and LLA herb pair (G-LLA) on myelosuppressed mice.

Methods

The mice myelosuppression model was established by intraperitoneal (i.p.) injection of cyclophosphamide (Cy). Hematopoietic function of bone marrow was measured by hemopoietic progenitor cell culture and peripheral blood count, and serum hemopoietic factors were tested by enzyme-linked immunosorbent assay. Bone marrow cell cycle was performed by flow cytometry. HPLC was used to measure 20 potential chemical components related to myelosuppression, including ginsenoside Rg₁, Re, Rb₁, Rc, Rb₂, Rb₃, Rd, Rk₃, Rh₄, 20 (S)-Rg₃, 20 (R)-Rg₃, Rk₁, Rg₅, salidroside, and so on.

Results

G, LLA, and G-LLA improved the amount of peripheral blood cells and bone marrow cells of myelosuppressed mice (P < 0.01). They significantly increased the colony quantity of colony-forming unit–granulocyte macrophage, burst-forming unit−erythroid, colony-forming unit−erythroid, and colony-forming unit−megakaryocyte and amount of G₂/M and S phase cells (P < 0.01). They also significantly decreased the amount of hematopoiesis-related cytokines (P < 0.01). The content of chemical components in G-LLA changed, and the change of rare saponin was the most obvious.

Conclusion

These results show that G-LLA herb pair might produce synergistic or complementary compatibility effects on bone marrow suppression after chemotherapy. It suggests that the substance basis of G-LLA for treating bone marrow suppression may be effective chemical components.