Yolonda L. Colson

Local drug delivery strategies for cancer treatment: gels, nanoparticles, polymeric films, rods, and wafers.

Polymer-based drug delivery depots have been investigated over the last several decades as a means to improve upon the lack of tumor targeting and severe systemic morbidities associated with intravenous chemotherapy treatments. These localized therapies exist in a variety of form factors designed to facilitate the delivery of drug directly to the site of disease in a controlled manner, sparing off-target tissue toxicities. Many of these depots are biodegradable and designed to maintain therapeutic concentrations of drug at the tumor site for a prolonged period of time. Thus a single implantation procedure is required, sometimes coincident with tumor excision surgery, and thereby biodegrading following complete release of the loaded active agent. Even though localized polymer depot delivery systems have been investigated, a surprisingly small subset of these technologies has demonstrated potentially curative preclinical results for cancer applications, and fewer have progressed toward commercialization. The aims of this article are to review the most well-studied and efficacious local polymer delivery systems from the last two decades, to examine the rationale for utilizing drug-eluting polymer implants in cancer patients, and to identify the patient cohorts that could most benefit from localized therapy. Finally, a discussion of the physiological barriers to localized therapy (i.e. drug penetration, transport), technical hurdles, and future outlook of the field is presented.

Expansile Nanoparticles: Synthesis, Characterization, and in Vivo Efficacy of an Acid-Responsive Polymeric Drug Delivery System

Nanoparticles are finding increased uses in drug delivery applications as a means to increase treatment efficacy and improve patient care. Here, we report engineered polymeric nanoparticles that undergo a hydrophobic to hydrophilic transition at pH 5 to afford swelling and rapid release of their contents. As our clinical interest lies in the prevention of lung tumor recurrence following resection, the nanoparticles were evaluated in a model mimicking microscopic disease, akin to residual occult tumor that can remain at the resection margin following surgery. Expansile nanoparticles loaded with paclitaxel, a poorly water-soluble anticancer drug, prevent establishment of lung cancer in vivo and are superior to the conventional drug delivery method for paclitaxel using Cremophor EL/ethanol.

Superhydrophobic Materials for Tunable Drug Release: Using Displacement of Air To Control Delivery Rates

We have prepared 3D superhydrophobic materials from biocompatible building blocks, where air acts as a barrier component in a porous electrospun mesh to control the rate at which drug is released. Specifically, we fabricated poly(ε-caprolactone) electrospun meshes containing poly(glycerol monostearate-co-ε-caprolactone) as a hydrophobic polymer dopant, which results in meshes with a high apparent contact angle. We demonstrate that the apparent contact angle of these meshes dictates the rate at which water penetrates into the porous network and displaces entrapped air. The addition of a model bioactive agent (SN-38) showed a release rate with a striking dependence on the apparent contact angle that can be explained by this displacement of air within the electrospun meshes. We further show that porous electrospun meshes with higher surface area can be prepared that release more slowly than control nonporous constructs. Finally, the entrapped air layer within superhydrophobic meshes is shown to be robust in the presence of serum, as drug-loaded meshes were efficacious against cancer cells in vitro for >60 days, thus demonstrating their applicability for long-term drug delivery.

Mixed allogeneic chimerism in the rat. Donor-specific transplantation tolerance without chronic rejection for primarily vascularized cardiac allografts.

Graft loss secondary to chronic rejection remains a major source of morbidity and mortality in solid organ transplantation. Mixed chimerism has been suggested as one potential approach to overcome this limitation. Until now, whether long-term tolerance for primarily vascularized allografts can be achieved with mixed chimerism has not been adequately assessed due to technical limitations in the mouse and the inability to establish a reliable model of mixed chimerism in the rat. We now report that stable multilineage mixed hematopoietic chimerism can be achieved following the transplantation of a mixture of T cell-depleted syngeneic and allogeneic bone marrow cells into myeloablated rat recipients using a number of MHC plus minor antigen-disparate donor and recipient strain combinations (F344+WF-->F344, F344+ACI-->F344, WF+F344-->WF, and WF+ACI-->WF). Ninety-one percent of animals engrafted with a level of lymphoid chimerism ranging between 12% and 93% (73.3 +/- 4.8%). Peripheral blood lymphocyte chimerism remained stable for up to 13 months after reconstitution. Multilineage chimerism for lymphoid (T and B cells) and myeloid (granulocyte and macrophage) lineages was present, which suggests that engraftment of the pluripotent rat stem cell had occurred. There was no clinical or histologic evidence of graft-versus-host disease. Donor-specific skin (mean survival time [MST] > or = 177 days) and primarily vascularized cardiac (MST > or = 213 days) grafts were accepted without evidence for acute or chronic rejection. In contrast, MHC-disparate third-party skin (MST = 14 days) and cardiac grafts (MST = 13 days) were rapidly rejected. The tolerance was systemic, since donor-specific tolerance was present in vitro as assessed by the mixed lymphocyte proliferation assay. These data suggest that mixed chimerism prevents graft loss secondary to chronic rejection in skin as well as primarily vascularized grafts. Furthermore, a rat model for mixed allogeneic chimerism may provide insight into the mechanisms involved in tolerance induction for a variety of allografts (lungs, small bowel, limb, etc.) not readily transplantable in mouse recipients.

3D superhydrophobic electrospun meshes as reinforcement materials for sustained local drug delivery against colorectal cancer cells.

In this work we expand upon a recently reported local drug delivery device, where air is used as a degradable component of our material to control drug release (J. Am. Chem. Soc. 2012, 134, 2016-2019). We consider its potential use as a drug loaded strip to provide both mechanical stability to the anastomosis, and as a means to release drug locally over prolonged periods for prevention of locoregional recurrence in colorectal cancer. Specifically, we electrospun poly(ε-caprolactone) (PCL) with the hydrophobic polymer dopant poly(glycerol monostearate-co-ε-caprolactone) (PGC-C18) and used the resultant mesh to control the release of two anticancer drugs (CPT-11 and SN-38). The increase in mesh hydrophobicity with PGC-C18 addition slows drug release both by the traditional means of drug diffusion, as well as by increasing the stability of the entrapped air layer to delay drug release. We demonstrate that superhydrophobic meshes have mechanical properties appropriate for surgical buttressing of the anastomosis, permit non-invasive assessment of mesh location and documentation of drug release via ultrasound, and release chemotherapy over a prolonged period of time (>90 days) resulting in significant tumor cytotoxicity against a human colorectal cell line (HT-29).

Lobectomy Versus Sublobar Resection for Small (2 cm or Less) Non-Small Cell Lung Cancers

BACKGROUND We evaluated a cohort of patients who underwent resection for small (2 cm or less) non-small cell lung cancer (NSCLC) to determine if there is an association between extent of resection (lobar versus sublobar resection) and local recurrence or survival. METHODS We reviewed 468 consecutive patients who underwent resection for small NSCLC at our institution between 2000 and 2005. We excluded patients who had neoadjuvant therapy, active noncutaneous malignancies, pure bronchioalveolar carcinoma, lymph node (n = 53) or distant metastases at diagnosis, or multicentric cancers. Clinicopathologic data, recurrence, and vital status as of June 15, 2010, were retrieved. Overall and recurrence-free survival from surgery rates were assessed. RESULTS Two hundred thirty-eight patients underwent resection for primary solitary small NSCLC. Lobectomy (n = 84) was associated with longer overall (p = 0.0027) and recurrence-free (p = 0.0496) survival. Patients who underwent sublobar resection were older (p < 0.0001) and had worse pulmonary function (p < 0.0014). While there was a trend toward increased rate of local recurrence for sublobar resection (16% versus 8%, p = 0.1117), there was no difference in distant recurrence. Moreover, when lymph nodes were sampled with sublobar resection, local recurrence rate and overall and recurrence-free survival distributions were similar to those for lobectomy. CONCLUSIONS Sublobar resection is reasonable in older patients with limited cardiopulmonary function. For healthy patients, however, lobectomy remains the standard therapy, with sublobar resection with lymph node sampling representing an alternative to consider. These findings support continued effort to conduct a randomized trial of lobar versus sublobar resection, such as CALGB 140503.

Lymphatic drainage of the peritoneal space: a pattern dependent on bowel lymphatics.

BackgroundUnderstanding lymph drainage patterns of the peritoneum could assist in staging and treatment of gastrointestinal and ovarian malignancies. Sentinel lymph nodes (SLNs) have been identified for solid organs and the pleural space. Our purpose was to determine whether the peritoneal space has a predictable lymph node drainage pattern.MethodsRats received intraperitoneal injections of near-infrared (NIR) fluorescent tracers: namely, quantum dots (designed for retention in SLNs) or human serum albumin conjugated with IRDye800 (HSA800; designed for lymphatic flow beyond the SLN). A custom imaging system detected NIR fluorescence at 10 and 20 minutes and 1, 4, and 24 hours after injection. To determine the contribution of viscera to peritoneal lymphatic flow, additional cohorts received bowel resection before NIR tracer injection. Associations with appropriate controls were assessed with the χ2 test.ResultsQuantum dots drained to the celiac, superior mesenteric, and periportal lymph node groups. HSA800 drained to these same groups at early time points but continued flowing to the mediastinal lymph nodes via the thoracic duct. After bowel resection, both tracers were found in the thoracic, not abdominal, lymph node groups. Additionally, HSA800 was no longer found in the thoracic duct but in the anterior chest wall and diaphragmatic lymphatics.ConclusionsThe peritoneal space drains to the celiac, superior mesenteric, and periportal lymph node groups first. Lymph continues via the thoracic duct to the mediastinal lymph nodes. Bowel lymphatics are a key determinant of peritoneal lymph flow, because bowel resection shifts lymph flow directly to the intrathoracic lymph nodes via chest wall lymphatics.

Characterization of a newly discovered T-cell receptor beta-chain heterodimer expressed on a CD8+ bone marrow subpopulation that promotes allogeneic stem cell engraftment.

The facilitating cell is a rare CD8+ bone marrow subpopulation that can enhance allogeneic hematopoietic stem cell engraftment across complete major histocompatibility complex barriers without inducing acute graft-versus-host disease. Here we describe a CD3ɛ-associated complex on the facilitating cell surface that consists of the T-cell receptor β-chain disulfide-linked to a previously unknown 33-kilodalton glycoprotein. Provisionally called FCp33, this glycoprotein does not represent any of the known protein chains or surrogates associated with CD3–T-cell receptor β. Expression of this CD3–T-cell receptor β–FCp33 complex directly correlates with the facilitating cells functional ability to enhance allogeneic stem cell engraftment in vivo.

EMBEDDED MULTICELLULAR SPHEROIDS AS A BIOMIMETIC 3D CANCER MODEL FOR EVALUATING DRUG AND DRUG-DEVICE COMBINATIONS

Multicellular aggregates of cells, termed spheroids, are of interest for studying tumor behavior and for evaluating the response of pharmacologically active agents. Spheroids more faithfully reproduce the tumor macrostructure found in vivo compared to classical 2D monolayers. We present a method for embedding spheroids within collagen gels followed by quantitative and qualitative whole spheroid and single cell analyses enabling characterization over the length scales from molecular to macroscopic. Spheroid producing and embedding capabilities are demonstrated for U2OS and MDA-MB-231 cell lines, of osteosarcoma and breast adenocarcinoma origin, respectively. Finally, using the MDA-MB-231 tumor model, the chemotherapeutic response between paclitaxel delivery as a bolus dose, as practiced in the clinic, is compared to delivery within an expansile nanoparticle. The expansile nanoparticle delivery route provides a superior outcome and the results mirror those observed in a murine xenograft model. These findings highlight the synergistic beneficial results that may arise from the use of a drug delivery system, and the need to evaluate both drug candidates and delivery systems in the research and preclinical screening phases of a new cancer therapy development program.

Graft produced interleukin-6 functions as a danger signal and promotes rejection after transplantation

Background. Interleukin (IL)-6 is a pleiotropic cytokine that functions in both the innate and adaptive immune responses. However, the role of IL-6 in allograft rejection remains poorly understood. Methods. In this study, we demonstrate a critical role for graft-produced IL-6 in allograft rejection in a murine model of cardiac allograft transplantation. Results. The results show that IL-6-deficient grafts transplanted into allogeneic wild-type recipients have significantly prolonged survival, approximately three times the survival time of wild-type controls. In contrast, allogeneic cardiac transplants into IL-6-deficient recipients do not have prolonged graft survival, indicating that donor graft cells are the relevant source of IL-6. Our investigation of potential mechanisms shows that graft-produced IL-6 promotes the activation of peripheral CD4 and CD8 T cells. Furthermore, we show that IL-6 deficiency prolongs graft survival only in the presence of CD25+ T cells that have a phenotype consistent with regulatory T cells. Interestingly, IL-6 production by the graft is triggered by antigen-independent innate immune mechanisms. Conclusions. Thus, our results suggest the paradigm that graft rejection versus tolerance is determined by a balance between the activation of effector T cells versus immune suppression by regulatory T cells, and that after transplantation, IL-6 functions as a systemic danger signal that overcomes constitutive immune suppression mediated by regulatory T cells and promotes the activation of effector T cells.