Impact of oral oncolytic initiation on medication adherence for pre-existing comorbid chronic conditions.

PURPOSE: Oral oncolytics have improved survival in hematological cancers like chronic myeloid leukemia, chronic lymphocytic leukemia/small lymphocytic lymphoma, and multiple myeloma; however, it is unclear of the extent to which initiating these treatments might impact adherence to oral therapies for pre-existing comorbid chronic conditions. METHODS: Adults diagnosed with and prescribed oral oncolytics for chronic myeloid leukemia, chronic lymphocytic leukemia/small lymphocytic lymphoma, or multiple myeloma between 2013 and 2016 and with continuous eligibility six months before and after oral oncolytic initiation were identified from the Truven Health MarketScan databases. Among those identified, patients with pre-existing diabetes, hypertension, and/or hyperlipidemia with ≥1 fill for oral comorbid therapies were selected. Adherence to oral oncolytics and comorbid therapies was measured using the proportion of days covered metric. Wilcoxon signed-rank tests assessed changes in adherence for comorbid therapies after initiation of an oral oncolytic. Unadjusted difference-in-difference models assessed the impact of adherence to oral oncolytics on changes in adherence to comorbid therapies. RESULTS: Significant reductions in adherence after oncolytic initiation were observed across the comorbid therapies and were highest for patients taking lipid-lower agents (10.7-15.6%). Unadjusted difference-in-difference models revealed consistent and significantly lower reductions in adherence for those taking antihypertensives (chronic myeloid leukemia: p = 0.03; chronic lymphocytic leukemia/small lymphocytic lymphoma: p = 0.007; multiple myeloma: p = 0.09) and adherent to oral oncolytics. CONCLUSION: Initiation of oral oncolytics may negatively impact adherence to oral therapies for chronic comorbid conditions, necessitating the need for medication management strategies to help patients adhere to their entire medication regimen.

Cyclic Stretch and Perfusion Bioreactor for Conditioning Large Diameter Engineered Tissue Tubes.

A cyclic stretch and perfusion bioreactor was designed to culture large diameter engineered tissue tubes for heart valve applications. In this bioreactor, tubular tissues consisting of dermal fibroblasts in a sacrificial fibrin gel scaffold were placed over porated latex support sleeves and mounted in a custom bioreactor. Pulsatile flow of culture medium into the system resulted in cyclic stretching as well as ablumenal, lumenal, and transmural flow (perfusion). In this study, lumenal remodeling, composition, and mechanical strength and stiffness were compared for tissues cyclically stretched in this bioreactor on either the porated latex sleeves or solid latex sleeves, which did not permit lumenal or transmural flow. Tissues cyclically stretched on porated sleeves had regions of increased lumenal remodeling and cellularity that were localized to the columns of pores in the latex sleeve. A CFD model was developed with COMSOL Multiphysics(®) to predict flow of culture medium in and around the tissue, and the predictions suggest that the enhanced lumenal remodeling was likely a result of elevated shear stresses and transmural velocity in these regions. This work highlights the beneficial effects of increased nutrient transport and flow stimulation for accelerating in vitro tissue remodeling.

Effects of Intermittent and Incremental Cyclic Stretch on ERK Signaling and Collagen Production in Engineered Tissue.

Intermittent cyclic stretching and incrementally increasing strain amplitude cyclic stretching were explored to overcome the reported adaptation of fibroblasts in response to constant amplitude cyclic stretching, with the goals of accelerating collagen production and understanding the underlying cell signaling. The effects of constant amplitude, intermittent, and incremental cyclic stretching regimens were investigated for dermal fibroblasts entrapped in a fibrin gel by monitoring the extracellular signal-regulated kinase (ERK1/2) and p38 pathways, collagen transcription, and finally the deposited collagen protein. Activation of ERK1/2, which has been shown to be necessary for stretch-induced collagen transcription, was maximal at 15 min and decayed by 1 h. ERK1/2 was reactivated by an additional onset of stretching or by an increment in the strain amplitude 6 h after the initial stimulus, which was approximately the lifetime of activated p38, a known ERK1/2 inhibitor. While both intermittent and incremental regimens reactivated ERK1/2, only incremental stretching increased collagen production compared to samples stretched with constant amplitude, resulting in a 37% increase in collagen per cell after 2 weeks. This suggests that a regimen with small, frequent increments in strain amplitude is optimal for this system and should be used in bioreactors for engineered tissues requiring high collagen content.

6-month aortic valve implantation of an off-the-shelf tissue-engineered valve in sheep.

Diseased aortic valves often require replacement, with over 30% of the current aortic valve surgeries performed in patients who will outlive a bioprosthetic valve. While many promising tissue-engineered valves have been created in the lab using the cell-seeded polymeric scaffold paradigm, none have been successfully tested long-term in the aortic position of a pre-clinical model. The high pressure gradients and dynamic flow across the aortic valve leaflets require engineering a tissue that has the strength and compliance to withstand high mechanical demand without compromising normal hemodynamics. A long-term preclinical evaluation of an off-the-shelf tissue-engineered aortic valve in the sheep model is presented here. The valves were made from a tube of decellularized cell-produced matrix mounted on a frame. The engineered matrix is primarily composed of collagen, with strength and organization comparable to native valve leaflets. In vitro testing showed excellent hemodynamic performance with low regurgitation, low systolic pressure gradient, and large orifice area. The implanted valves showed large-scale leaflet motion and maintained effective orifice area throughout the duration of the 6-month implant, with no calcification. After 24 weeks implantation (over 17 million cycles), the valves showed no change in tensile mechanical properties. In addition, histology and DNA quantitation showed repopulation of the engineered matrix with interstitial-like cells and endothelialization. New extracellular matrix deposition, including elastin, further demonstrates positive tissue remodeling in addition to recellularization and valve function. Long-term implantation in the sheep model resulted in functionality, matrix remodeling, and recellularization, unprecedented results for a tissue-engineered aortic valve.

Combating Adaptation to Cyclic Stretching By Prolonging Activation of Extracellular Signal-Regulated Kinase.

In developing implantable tissues based on cellular remodeling of a fibrin scaffold, a key indicator of success is high collagen content. Cellular collagen synthesis is stimulated by cyclic stretching but is limited by cellular adaptation. Adaptation is mediated by deactivation of extracellular signal-regulated kinase (ERK); therefore inhibition of ERK deactivation should improve mechanically stimulated collagen production and accelerate the development of strong engineered tissues. The hypothesis of this study is that p38 mitogen activated protein kinase (p38) activation by stretching limits ERK activation and that chemical inhibition of p38/isoforms with SB203580 will increase stretching-induced ERK activation and collagen production. Both p38 and ERK were activated by 15 minutes of stretching but only p38 remained active after 1 hour. After an effective dose of inhibitor was identified using cell monolayers, 5 M SB203580 was found to increase ERK activation by two-fold in cyclically stretched fibrin-based tissue constructs. When 5 M SB203580 was added to the culture medium of constructs exposed to three weeks of incremental amplitude cyclic stretch, 2.6 fold higher stretching-induced total collagen was obtained. In conclusion, SB203580 circumvents adaptation to stretching induced collagen production and may be useful in engineering tissues where mechanical strength is a priority.