Publications

Semen harbors amyloids that enhance human immunodeficiency virus type 1 (HIV-1) infection. We set out to identify factors that bind these amyloids and to determine whether these factors modulate amyloid-mediated HIV-enhancing activity. Using biochemical and mass spectrometric approaches, we identified fibronectin as a consistent interaction partner. Although monomeric fibronectin did not enhance HIV infection, it synergistically increased the infectivity enhancement activity of the amyloids. Depletion of fibronectin decreased the enhancing activity of semen, suggesting that interfering with the binding interface between fibronectin and the amyloids could be an approach to developing a novel class of microbicides targeting the viral-enhancing activity of semen.

Central nervous system tuberculosis (CNS TB) represents one of the most devastating manifestations of TB. HIV dramatically increases the risk of TB disease, including CNS TB. Early recognition and treatment of CNS TB, and TB meningitis in particular, is of critical importance to reducing disability and death associated with CNS TB. The diagnosis and treatment of HIV-associated CNS TB presents particular challenges for clinicians due to the increased risk of other CNS infections and malignancies, atypical cerebrospinal fluid characteristics, drug-drug interactions, timing of antiretroviral therapy and immune reconstitution inflammatory syndrome, and the increased risk of poor clinical outcomes in HIV-infected compared with HIV-uninfected CNS TB patients. The authors review recent updates and highlight challenges specific to CNS TB in the HIV-infected patient.

Expression quantitative trait loci (eQTL) mapping is a tool that can systematically identify genetic variation affecting gene expression. eQTL mapping studies have shown that certain genomic locations, referred to as regulatory hotspots, may affect the expression levels of many genes. Recently, studies have shown that various confounding factors may induce spurious regulatory hotspots. Here, we introduce a novel statistical method that effectively eliminates spurious hotspots while retaining genuine hotspots. Applied to simulated and real datasets, we validate that our method achieves greater sensitivity while retaining low false discovery rates compared to previous methods.

Directed migration of diverse cell types plays a critical role in biological processes ranging from development and morphogenesis to immune response, wound healing, and regeneration. However, techniques to direct, manipulate, and study cell migration in vitro and in vivo in a specific and facile manner are currently limited. We conceived of a strategy to achieve direct control over cell migration to arbitrary user-defined locations, independent of native chemotaxis receptors. Here, we show that genetic modification of cells with an engineered G protein-coupled receptor allows us to redirect their migration to a bioinert drug-like small molecule, clozapine-N-oxide (CNO). The engineered receptor and small-molecule ligand form an orthogonal pair: The receptor does not respond to native ligands, and the inert drug does not bind to native cells. CNO-responsive migration can be engineered into a variety of cell types, including neutrophils, T lymphocytes, keratinocytes, and endothelial cells. The engineered cells migrate up a gradient of the drug CNO and transmigrate through endothelial monolayers. Finally, we demonstrate that T lymphocytes modified with the engineered receptor can specifically migrate in vivo to CNO-releasing beads implanted in a live mouse. This technology provides a generalizable genetic tool to systematically perturb and control cell migration both in vitro and in vivo. In the future, this type of migration control could be a valuable module for engineering therapeutic cellular devices.

PURPOSE

The highly effective treatment of human epidermal growth factor receptor (HER) 2-amplified breast cancer has proven challenging because of a signal buffering capacity inherent in the functionally relevant HER2-HER3 target. HER2-HER3 signaling can be inactivated by doses of lapatinib that fully inactivate the HER2 kinase. In mouse models, such doses are not tolerable in continuous administration, but they are tolerable and highly effective in intermittent dosing. We pursued the clinical translation of this treatment hypothesis.

PATIENTS AND METHODS

We conducted a phase I dose-escalation study in women with advanced HER2-overexpressing breast cancer. Lapatinib was administered on days 1 through 5 of repeating 14-day cycles. Dose escalation was conducted using a 3+3 design with plasma lapatinib level monitoring.

RESULTS

Forty patients were evaluable for toxicity, and 34 patients were evaluable for dose-limiting toxicity (DLT). Lapatinib dose was escalated to 7,000 mg per day in twice-daily dosing with no DLTs; however, plasma lapatinib concentrations plateaued in this dose range. Additional cohorts evaluated strategies to increase lapatinib exposure, including the food effect, CYP3A4 inhibition, and dose fractionation. Of these, only ketoconazole was able to increase lapatinib exposure, despite highly variable lapatinib bioavailability. Intolerable exposure levels were not encountered. Eight patients (20%) experienced grade 3 diarrhea. Six patients achieved a response, and dramatic responses were seen in three patients with lapatinib concentrations approaching 10,000 ng/mL.

CONCLUSION

Lapatinib exposure can be safely and significantly increased through intermittent dosing but reaches a ceiling that currently impedes clinical translation of the treatment hypothesis. Preliminary efficacy data suggest that exposures approaching those seen in mouse models can result in highly significant tumor responses.