Phage Capsids as Gated, Long-Persistence, Uniform Drug Delivery Vehicles

Abstract

Over the last 25 years, cancer therapies have improved survivorship. Yet, metastatic cancers remain deadly. Therapies are limited by inadequate targeting. Our goal is to develop a new drug delivery vehicle (DDV)-based strategy that improves targeting of drug delivery to solid tumors. We begin with a capsid nanoparticle derived from bacteriophage (phage) T3, a phage that naturally has high persistence in murine blood. This capsid has gating capacity. For rapidly detecting loading in this capsid, here, we describe procedures of native agarose gel electrophoresis, coupled with fluorescence-based detection of loaded molecules. We observe the loading of two fluorescent compounds: the dye, GelStar, and the anticancer drug, bleomycin. The optimal emission filters were found to be orange and green, respectively. The results constitute a first milestone in developing a drug-loaded DDV that does not leak when in blood, but unloads its cargo when in a tumor.

Optimizing Anti-Viral Vaccine Responses: Input from a Non-Specialist

“…The option proposed above is obviously a product of the author's history. Indeed, the phage isolation aspect overlaps the author's previous proposals for resolving current crises in the therapy of multi-drug-resistant bacterial infections [36] and metastatic cancer [37]. Investigation of natural phage bioengineering has produced a framework for understanding and curing neurodegenerative diseases [38].…”

A Perspective on Studies of Phage DNA Packaging Dynamics

“…This portal is discussed in the articles presented here. Phage T4 has been shown to be gated for ethidium [ 47 ]; a phage T3 capsid has been shown to be gated for GelStar [ 48 ]. Both these phages exhibit high murine persistence [ 25 ], which is potentially as critical for a DDV as it is for phage therapy of infectious disease.…”

Basics for Improved Use of Phages for Therapy

“…The 1940 experiment is not yet, to our knowledge, repeated with a phage well-characterized by current standards. We chose to repeat this experiment with phage T3, as we had begun to test the possibility of using a T3 capsid as a DDV [ 70 ].…”

“…When developing an anti-tumor strategy, one wants to know that the strategy includes ways to manage the two success-blocking limitations that have arisen with all past anti-tumor drug therapy of metastatic cancer: cancer cell mutation to drug resistance [ 83 , 84 ], and drug toxicity to healthy cells [ 85 , 86 , 87 ]. If we have high persistence phage-based DDVs, then one limitation-bypassing strategy has the following tactical objectives: (1) zero DDV uptake into healthy tissue; (2) zero drug leakage from the DDV during circulation in blood (see [ 70 ]); (3) uptake, not necessarily rapid (possibly, 1–2 days), into tumors; and (4) rapid (i.e., a matter of minutes) drug release in tumors, which might be achievable via gates that are naturally on dsDNA phage capsids [ 70 ]. Of course, meeting these objectives is beyond our current capacity.…”

“…The central point is that, with high persistence and low leakage, a DDV could circulate for hours/days while slowly accumulating in tumors. Finally, the point has been made [ 70 ] that partial reaching of the above tactical objectives may be sufficient, as the probability of a toxicity-generating series of tandem DDV-associated events is the product of the probabilities of each of the events.…”