Michal T. Krauze

Prognostic significance of autoimmunity during treatment of melanoma with interferon

Since the pivotal cooperative group trials in the 1980s-90s,, high-dose interferon (HDI) has been the standard of adjuvant therapy. Despite multiple other trials evaluating potential new therapies in melanoma, HDI remains the only FDA-approved therapy for stage IIB and III melanoma. Initial reports from the more recent phase III international trials of modifications of the original HDI regimen linked the appearance of autoimmunity with improved outcomes of disease. Trials of high-dose interleukin-2, many years earlier, reported anecdotal observations that were consistent with the hypothesis that autoimmunity and clinical benefit of immunotherapies of melanoma are linked with one another. The only prospectively conducted study examining the appearance of clinical and laboratory evidence of autoimmunity during HDI therapy was published by Gogas and colleagues, demonstrating statistically significant impact on relapse-free survival and overall survival. Retrospectively conducted studies of different intermediate dosage regimens of interferon (IFN) have not fully confirmed the linkage of serological evidence of autoimmunity and improved survival outcomes. With the emergence of new immunotherapies in treatment of melanoma, this review highlights the importance of autoimmunity for future applications in melanoma and reviews significant differences of past studies evaluating the appearance of autoimmunity during IFN therapy in high-risk melanoma.Since the pivotal cooperative group trials in the 1980’s-90’s,, high-dose interferon (HDI) has been the standard of adjuvant therapy. Despite multiple other trials evaluating potential new therapies in melanoma, HDI remains the only FDA-approved therapy for stage IIB and III melanoma. Initial reports from the more recent phase III international trials of modifications of the original HDI regimen linked the appearance of autoimmunity with improved outcomes of disease. Trials of high-dose interleukin-2, many years earlier, reported anecdotal observations that were consistent with the hypothesis that autoimmunity and clinical benefit of immunotherapies of melanoma are linked with one another. The only prospectively conducted study examining the appearance of clinical and laboratory evidence of autoimmunity during HDI therapy was published by Gogas and colleagues, demonstrating statistically significant impact on relapse-free survival and overall survival. Retrospectively conducted studies of different intermediate dosage regimens of interferon (IFN) have not fully confirmed the linkage of serological evidence of autoimmunity and improved survival outcomes. With the emergence of new immunotherapies in treatment of melanoma, this review highlights the importance of autoimmunity for future applications in melanoma and reviews significant differences of past studies evaluating the appearance of autoimmunity during IFN therapy in high-risk melanoma.

Gadolinium-loaded liposomes allow for real-time magnetic resonance imaging of convection-enhanced delivery in the primate brain

Drug delivery to brain tumors has long posed a major challenge. Convection-enhanced delivery (CED) has been developed as a drug delivery strategy to overcome this difficulty. Ideally, direct visualization of the tissue distribution of drugs infused by CED would assure successful delivery of therapeutic agents to the brain tumor while minimizing exposure of the normal brain. We previously developed a magnetic resonance imaging (MRI)-based method to visualize the distribution of liposomal agents after CED in rodent brains. In the present study, CED of liposomes was further examined in the non-human primate brain (n = 6). Liposomes containing Gadoteridol, DiI-DS, and rhodamine were infused in corona radiata, putamen nucleus, and brain stem. Volume of distribution was analyzed for all delivery locations by histology and MR imaging. Real-time MRI monitoring of liposomes containing gadolinium allowed direct visualization of a robust distribution. MRI of liposomal gadolinium was highly accurate at determining tissue distribution, as confirmed by comparison with histological results from concomitant administration of fluorescent liposomes. Linear correlation for liposomal infusions between infusion volume and distribution volume was established in all targeted locations. We conclude that an integrated strategy combining liposome/nanoparticle technology, CED, and MRI may provide new opportunities for the treatment of brain tumors. Our ability to directly monitor and to control local delivery of liposomal drugs will most likely result in greater clinical efficacy when using CED in management of patients.

Novel Nanoliposomal CPT-11 Infused by Convection-Enhanced Delivery in Intracranial Tumors: Pharmacology and Efficacy

We hypothesized that combining convection-enhanced delivery (CED) with a novel, highly stable nanoparticle/liposome containing CPT-11 (nanoliposomal CPT-11) would provide a dual drug delivery strategy for brain tumor treatment. Following CED in rat brains, tissue retention of nanoliposomal CPT-11 was greatly prolonged, with >20% injected dose remaining at 12 days for all doses. Tissue residence was dose dependent, with doses of 60 microg (3 mg/mL), 0.8 mg (40 mg/mL), and 1.6 mg (80 mg/mL) resulting in tissue half-life (t(1/2)) of 6.7, 10.7, and 19.7 days, respectively. In contrast, CED of free CPT-11 resulted in rapid drug clearance (tissue t(1/2) = 0.3 day). At equivalent CED doses, nanoliposomal CPT-11 increased area under the time-concentration curve by 25-fold and tissue t(1/2) by 22-fold over free CPT-11; CED in intracranial U87 glioma xenografts showed even longer tumor retention (tissue t(1/2) = 43 days). Plasma levels were undetectable following CED of nanoliposomal CPT-11. Importantly, prolonged exposure to nanoliposomal CPT-11 resulted in no measurable central nervous system (CNS) toxicity at any dose tested (0.06-1.6 mg/rat), whereas CED of free CPT-11 induced severe CNS toxicity at 0.4 mg/rat. In the intracranial U87 glioma xenograft model, a single CED infusion of nanoliposomal CPT-11 at 1.6 mg resulted in significantly improved median survival (>100 days) compared with CED of control liposomes (19.5 days; P = 4.9 x 10(-5)) or free drug (28.5 days; P = 0.011). We conclude that CED of nanoliposomal CPT-11 greatly prolonged tissue residence while also substantially reducing toxicity, resulting in a highly effective treatment strategy in preclinical brain tumor models.

Convection-enhanced delivery of Ls-TPT enables an effective, continuous, low-dose chemotherapy against malignant glioma xenograft model

Treatment of malignant gliomas represents one of the most formidable challenges in oncology. The combination of surgery, radiation, and chemotherapy yields median survivals of less than one year. Here we demonstrate the use of a minimally invasive surgical technique, convection-enhanced delivery (CED), for local administration of a novel nanoparticle liposome containing topotecan. CED of this liposomal topotecan (Ls-TPT) resulted in extended brain tissue retention (t1/2 = 1.5 days), whereas free topotecan was rapidly cleared (t1/2 = 0.1 days) after CED. The favorable pharmacokinetic profile of extended topotecan release for about seven days, along with biodistribution featuring perivascular accumulation of the nanoparticles, provided, in addition to the known topoisomerase I inhibition, an effective antiangiogenic therapy. In the rat intracranial U87MG tumor model, vascular targeting of Ls-TPT with CED was associated with reductions in laminin expression and vascular density compared to free topotecan or control treatments. A single CED treatment on day 7 showed that free topotecan conferred no survival benefit versus control. However, Ls-TPT produced a significant (P = 0.0002) survival benefit, with six of seven complete cures. Larger U87MG tumors, where CED of Ls-TPT on day 12 resulted in one of six cures, indicated the necessity to cover the entire tumor with the infused therapeutic agent. CED of Ls-TPT was also efficacious in the intracranial U251MG tumor model (P = 0.0005 versus control). We conclude that the combination of a novel nanoparticle Ls-TPT and CED administration was very effective in treating experimental brain tumors.

Convection-enhanced delivery of nanoliposomal CPT-11 (irinotecan) and PEGylated liposomal doxorubicin (Doxil) in rodent intracranial brain tumor xenografts

We have previously shown that convection-enhanced delivery (CED) of highly stable nanoparticle/liposome agents encapsulating chemotherapeutic drugs is effective against intracranial rodent brain tumor xenografts. In this study, we have evaluated the combination of a newly developed nanoparticle/liposome containing the topoisomerase I inhibitor CPT-11 (nanoliposomal CPT-11 [nLs-CPT-11]), and PEGylated liposomal doxorubicin (Doxil) containing the topoisomerase II inhibitor doxorubicin. Both drugs were detectable in the CNS for more than 36 days after a single CED application. Tissue half-life was 16.7 days for nLs-CPT-11 and 10.9 days for Doxil. The combination of the two agents produced synergistic cytotoxicity in vitro. In vivo in U251MG and U87MG intracranial rodent xenograft models, CED of the combination was also more efficacious than either agent used singly. Analysis of the parameters involved in this approach indicated that tissue pharmacokinetics, tumor microanatomy, and biochemical interactions of the drugs all contributed to the therapeutic efficacy observed. These findings have implications for further clinical applications of CED-based treatment of brain tumors.

Tissue affinity of the infusate affects the distribution volume during convection-enhanced delivery into rodent brains: Implications for local drug delivery

Convection-enhanced delivery (CED) is a recently developed technique for local delivery of agents to a large volume of tissue in the central nervous system (CNS). We have previously reported that this technique can be applied to CNS delivery of nanoparticles including viruses and liposomes. In this paper, we describe the impact of key physical and chemical properties of infused molecules on the extent of CED-mediated delivery. For simple infusates, CED distribution was significantly increased if the infusate was more hydrophilic or had less tissue affinity. Encapsulation of tissue-affinitive molecules by neutral liposomes significantly increased their tissue distribution. The poorer brain distribution observed with cationic liposomes, due to their greater tissue affinity, was completely overcome by PEGylation, which provides steric stabilization and reduced surface charge. Finally, liposomal encapsulation of doxorubicin reduced its tissue affinity and substantially increased its distribution within brain tumor tissue. Taken together, the physical and chemical properties of drugs, small molecules and macromolecular carriers determine the tissue affinity of the infusate and strongly affect the distribution of locally applied agents. Thus, an increased and more predictable tissue distribution can be achieved by reducing the tissue affinity of the infusate using appropriately engineered liposomes or other nanoparticles.

Real-time Imaging and Quantification of Brain Delivery of Liposomes

AbstractThe surgical delivery of therapeutic agents into the parenchyma of the brain is problematic because it has been virtually impossible to know with any certainty where infused material is going, and how much to infuse. We have started to use liposomes loaded with Gadoteridol (GDL) as a tracer that allows us to follow infusions in real-time on magnetic resonance imaging (MRI). MRI allows precise tracking and measurement of liposomes loaded with markers and therapeutics. This review provides an overview of real-time delivery of liposomes to the central nervous system (CNS), and discusses the technical aspects of delivery, liposomes as colloidal systems of delivery, real-time distribution of liposomes in CNS, and quantification of liposome distribution. Our data suggests that real-time monitoring of liposomal drug infusion is likely to improve outcomes of clinical trials where convection-enhanced delivery (CED) is being used to target drugs to specific brain structures through limitation of systemic toxicity and reduction of side effects. This review is a summary of work done by our group over the past four years.

Canine model of convection-enhanced delivery of liposomes containing CPT-11 monitored with real-time magnetic resonance imaging: Laboratory investigation

OBJECT Many factors relating to the safety and efficacy of convection-enhanced delivery (CED) into intracranial tumors are poorly understood. To investigate these factors further and establish a more clinically relevant large animal model, with the potential to investigate CED in large, spontaneous tumors, the authors developed a magnetic resonance (MR) imaging-compatible system for CED of liposomal nanoparticles into the canine brain, incorporating real-time MR imaging. Additionally any possible toxicity of liposomes containing Gd and the chemotherapeutic agent irinotecan (CPT-11) was assessed following direct intraparenchymal delivery. METHODS Four healthy laboratory dogs were infused with liposomes containing Gd, rhodamine, or CPT-11. Convection-enhanced delivery was monitored in real time by sequential MR imaging, and the volumes of distribution were calculated from MR images and histological sections. Assessment of any toxicity was based on clinical and histopathological evaluation. Convection-enhanced delivery resulted in robust volumes of distribution in both gray and white matter, and real-time MR imaging allowed accurate calculation of volumes and pathways of distribution. RESULTS Infusion variability was greatest in the gray matter, and was associated with leakage into ventricular or subarachnoid spaces. Complications were minimal and included mild transient proprioceptive deficits, focal hemorrhage in 1 dog, and focal, mild perivascular, nonsuppurative encephalitis in 1 dog. CONCLUSIONS Convection-enhanced delivery of liposomal Gd/CPT-11 is associated with minimal adverse effects in a large animal model, and further assessment for use in clinical patients is warranted. Future studies investigating real-time monitored CED in spontaneous gliomas in canines are feasible and will provide a unique, clinically relevant large animal translational model for testing this and other therapeutic strategies.

Effects of the perivascular space on convection-enhanced delivery of liposomes in primate putamen

Convection-enhanced delivery has recently entered the clinic and represents a promising new therapeutic option in the field of neurodegenerative diseases and treatment of brain tumors. Understanding of the principles governing delivery and flow of macromolecules within the CNS is still poorly understood and requires more investigation of the microanatomy and fluid dynamics of the brain. Our previously established, reflux-free convection-enhanced delivery (CED) technique and real-time imaging MR method for monitoring CED delivery of liposomes in primate CNS allowed us to closely monitor infusions of putamen. Our findings indicate that CED in putamen is associated with perivascular transport of liposomes, throughout CNS arteries. The results may explain side effects seen in current clinical trials using CED. In addition, they clearly show the necessity for a monitoring technique for future direct delivery of therapeutic agents to the human central nervous system. Based on these findings, we believe that the physiological concept that the perivascular space serves as a conduit for distribution of endogenous molecules within the CNS also applies to interstitially infused agents.

Convection-enhanced delivery of a topoisomerase I inhibitor (nanoliposomal topotecan) and a topoisomerase II inhibitor (pegylated liposomal doxorubicin) in intracranial brain tumor xenografts

Despite multimodal treatment options, the response and survival rates for patients with malignant gliomas remain dismal. Clinical trials with convection-enhanced delivery (CED) have recently opened a new window in neuro-oncology to the direct delivery of chemotherapeutics to the CNS, circumventing the blood-brain barrier and reducing systemic side effects. Our previous CED studies with liposomal chemotherapeutics have shown promising antitumor activity in rodent brain tumor models. In this study, we evaluated a combination of nanoliposomal topotecan (nLs-TPT) and pegylated liposomal doxorubicin (PLD) to enhance efficacy in our brain tumor models, and to establish a CED treatment capable of improving survival from malignant brain tumors. Both liposomal drugs decreased key enzymes involved in tumor cell replication in vitro. Synergistic effects of nLs-TPT and PLD on U87MG cell death were found. The combination displayed excellent efficacy in a CED-based survival study 10 days after tumor cell implantation. Animals in the control group and those in singleagent groups had a median survival of less than 30 days, whereas the combination group experienced a median survival of more than 90 days. We conclude that CED of two liposomal chemotherapeutics (nLs-TPT and PLD) may be an effective treatment option for malignant gliomas.