Cancer vaccines initiate antitumor responses in a subset of patients, but the lack of clinically meaningful biomarkers to predict treatment response limits their development. Here, we design ...multifunctional RNA-loaded magnetic liposomes to initiate potent antitumor immunity and function as an early biomarker of treatment response. These particles activate DCs more effectively than electroporation leading to superior inhibition of tumor growth in treatment models. Inclusion of iron oxide enhances DC transfection and enables tracking of DC migration with Magnetic Resonance Imaging (MRI). We show that T2*-weighted MRI intensity in lymph nodes is a strong correlate of DC trafficking and is an early predictor of antitumor response. In preclinical tumor models, MRI-predicted “responders” identified two days after vaccination had significantly smaller tumors 2-5 weeks after treatment and lived 73% longer than MRI-predicted “non-responders.” These studies therefore provide a simple, scalable nanoparticle formulation to generate robust antitumor immune responses and predict individual treatment outcome with MRI.
Abstract
BACKGROUND
Cancer vaccines are a promising approach to personalized cancer immunotherapy, but the lack of meaningful biomarkers of patient response to treatment limits their development. We ...recently reported in a randomized and blinded pilot clinical trial that RNA-pulsed dendritic cells (DCs) combined with tetanus-diphtheria (Td) booster vaccine prolong progression-free and overall survival in patients with glioblastoma (Mitchell et al, Nature 2015). Furthermore, we demonstrated that DC migration to lymph nodes assessed by SPECT/CT imaging strongly correlates with clinical outcomes. While this finding may provide a novel imaging biomarker for response to DC vaccines, the complexity and regulatory requirements of nuclear medicine-based imaging of radiolabeled cells limits widespread utilization of this technique. We have therefore developed bi-functional RNA-loaded magnetic nanoparticles to load DCs with RNA-encoded antigens, enhance DC migration to lymph nodes, and track migration in vivo using an MRI-based imaging modality.
METHODS
Immune-stimulatorycationic liposomes with iron oxide nanoparticle cores were complexed with mRNA. The resulting iron oxide-loaded RNA-NPs (IO-RNA-NPs) were used to transfect DCs ex vivo in the presence of a magnetic field. IO-RNA-NP-loaded DCs were then injected intradermally into tumor-bearing C57Bl6 mice and tracked noninvasively with T2-weighted 11T MRI.
RESULTS
The presence of iron oxide in RNA-NPs did not significantly alter particle characteristics. Additionally, inclusion of iron oxide within RNA-NPs enabled magnetically enhanced transfection through application of external magnetic fields. Compared to RNA electroporation, IO-RNA-NP loading enhanced production of inflammatory cytokines and DC migration to lymph nodes. IO-RNA-NPs also produced a reduction in T2-weighted MRI intensity and an increase in MRI-detected lymph node size that correlated directly with the number of iron oxide loaded DCs in treated lymph nodes, inhibition of tumor growth, and survival in murine tumor models.
CONCLUSION
This data suggests that IO-RNA-NPs enhance DC activation and establish MRI-detected dendritic cell migration as a biomarker of antitumor vaccine response.
Abstract
BACKGROUND
Brain tumors are particularly difficult to treat due to their relative isolation behind the blood brain barrier. Cytotoxic T cells elicited by cancer vaccines are capable of ...penetrating this barrier, but are limited by innate immune cells in tumor microenvironments that inhibit T cell function. There is therefore an unmet need for a method to reprogram the immune cells in the tumor microenvironment to promote antitumor T cell responses.
OBJECTIVE
We previously reported that systemically administered liposomes bearing RNA encoding tumor antigens profoundly activate innate immune cells in reticuloendothelial system (RES) organs. Here, we report a modified liposome formulation capable of redirecting this immunomodulatory nucleic acid cargo to immune cells in brain tumors.
APPROACH
Cationic liposomes with varying compositions were loaded with Cy3-labelled RNA or siRNA and injected intravenously into glioma-bearing mice. RNA uptake was assessed with flow cytometry and immunofluorescence microscopy after 18 hours.
RESULTS
Inclusion of cholesterol within liposomes increased mRNA uptake in intracranial GL261 and KR158b tumors after systemic injection in a dose-dependent manner. Optimized tumor-homing liposomes delivered mRNA encoding tumor antigens to CD45+ immune cells in both tumors. These liposomes were also used to deliver siRNA against programmed death ligand 1 (PDL1). siRNA-loaded liposomes reduced PDL1 expression on dendritic cells ex vivo and on transfected CD45+ cells in murine brain tumors.
CONCLUSIONS
Our optimized liposomes effectively deliver mRNA and siRNA to immune cells in multiple murine brain tumors. Future work will consider the mechanism of this enhanced delivery and the use of tumor-homing liposomes to deliver other immunomodulatory biomolecules.
Abstract
INTRODUCTION
Immunotherapy is remarkably effective, yet tumor escape is common. Herein, we investigated tumor escape after adoptive cellular therapy (ACT) in intractable glioma models. These ...studies revealed multiple mechanisms of escape including a shift in immunogenic tumor antigens, downregulation of MHC-I, and upregulation of checkpoint molecules. Despite these changes, we HYPOTHESIZED that a new population of escape variant-specific polyclonal T cells could be generated to target immune-escaped tumors through using tumor escape variant RNA.
METHODS
We studied KR158B-luc glioma-bearing mice during treatment with ACT with polyclonal tumor-specific T cells. We tested the immunogenicity of primary and escaped tumors using T cell restimulation assays. We used flow cytometry and RNA profiling of whole tumors to further define escape mechanisms. To treat immune-escaped tumors, we generated escape variant-specific T cells through the use of escape variant total tumor RNA and administered these cells as ACT.
RESULTS
Escape mechanisms included a shift in immunogenic tumor antigens, downregulation of major histocompatibility complex (MHC) class I by 50%, and upregulation of checkpoint molecules. This included activated T cells and NK cells from tumor-draining lymph nodes expressing 50% and 30% PD-1 after ACT. Importantly, polyclonal T cells specific for escape variants displayed greater recognition of escaped tumors than primary tumors. When administered as ACT, these T cells prolonged median survival of escape variant-bearing mice by 60% (24 to 33 days, p=.0003). The rational combination of ACT with PD-1 blockade prolonged median survival of escape variant glioma-bearing mice by 110% and was dependent upon NK cells and T cells as determined by cell depletion experiments. To prevent escape from primary tumors, we combined ACT with PD-1 blockade to yield 71% long-term cures in KR158B-luc-bearing mice.
CONCLUSIONS
These findings suggest that the immune landscape of brain tumors is markedly different post-immunotherapy yet can still be targeted with immunotherapy.
Postoperative opioid abuse following surgery is a major concern. This study sought to create an opioid reduction toolkit to reduce the number of narcotics prescribed and consumed while increasing ...awareness of safe disposal in pancreatectomy patients.
Prescription, consumption, and refill request data for postoperative opioids were collected from patients receiving an open pancreatectomy before and after the implementation of an opioid reduction toolkit. Outcomes included safe disposal practice awareness for unused medication.
159 patients were included in the study: 24 in the pre-intervention and 135 in the post-intervention group. No significant demographic or clinical differences existed between groups. Median morphine milliequivalents (MMEs) prescribed were significantly reduced from 225 (225–310) to 75 (75–113) in the post-intervention group (p < 0.0001). Median MMEs consumed were significantly reduced from 109 (111–207) to 15 (0–75), p < 0.0001), as well. Refill request rates remained equivalent during the study (Pre: 17% v Post: 13%, p = 0.9) while patient awareness of safe disposal increased (Pre: 25% v Post: 62%, p < 0.0001).
An opioid reduction toolkit significantly reduced the number of postoperative opioids prescribed and consumed after open pancreatectomy, while refill request rates remained the same and patients’ awareness of safe disposal increased.
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