Design and Development of Theranostic Nanomedicines - Nanotechnology for Biomedical Imaging and Diagnostics - page 444

to polymeric nanocarriers. For example, an nir dye, Cy5.5, and an anticancer drug,
pTX, were attached to glycol chitosan-based polymeric nanoparticles [162]. In vivo ,
these nanoparticles showed fourfold tumor/normal fluorescence signal contrast.
Furthermore, they demonstrated significantly improved anticancer efficacy in a variety
of tumor mouse models over free drugs, mainly due to the passive targeting effect.
other than fluorescence imaging, Mri is also commonly used to image theranostic
polymers. as mentioned earlier, many polymeric nanoparticles have been developed
based on magnetic nanoparticles. For example, hpMa copolymers with DoX and
gemcitabine were shown to circulate for prolonged periods of time and localize to
tumors both effectively and selectively under Mri [167]. in rat prostate carcinoma
tumor model, the copolymers were shown to interact synergistically with radio-
therapy, with radiotherapy increasing the tumor accumulation of the copolymers, and
with the copolymers increasing the therapeutic index of radiochemotherapy (both
for DoX and for gemcitabine).

15.5 pharmaceutical aspects of theranostics

pharmaceutical design and development approaches to theranostic nanomedicine
have not been fully explored yet. Throughout this chapter, we argued for bringing
pharmaceutical principles to early stages of development with hope that these
would increase likelihood of success in the clinic. We talked about complexity of
theranostic nanomedicines and shared a few examples where this was very evident.
how this complexity of theranostic nanomedicines will play out in the real world
when they are converted into medicines on the market is yet to be seen. as we con-
tinue to work on theranostic nanomedicine, we can learn from existing nanomedi-
cine research and hopefully with the use of molecular imaging surpass many current
challenges. recently, venditto and szoka exclaimed in their comprehensive review
on cancer nanomedicines entitled “so Many papers and so Few Drugs!” [174]. in
their critical overview of recent literature, they designated a timeline for nanomedi-
cine development, which includes invention phase, innovation phase, and imitation
phase. They point out to proliferation of nanomedicines with somewhat modest or
moderate improvements over existing reports. Could it be that theranostic nano-
medicine is riding the wave of existing innovation in nanomedicine? or can ther-
anostic nanomedicine stand alone as the solution for remaining challenges in
nanomedicine such as lack of data supporting dosing in humans, direct measure-
ments of efficacy, ability to personalize treatment to disease state, and whole-body
state in an individual patient, mechanistic insights into nanomedicine effects on the
body, and body effects on the nanomedicine? We would like to argue that if theranos-
tic nanomedicines are designed rationally as future medicines, we could not only get
closer to the goal of personalized medicine but also it can help us understand better
the nanomedicine formulations in the body. Further, theranostic nanomedicines offer
an extended value of becoming powerful probes for deducing disease mechanisms
and mechanisms of drugs in live subjects, whether animals or people. For example,
one can imagine a theranostic liposome, where the imaging agent is a biosensor for
a particular change in the body that is expected only at a certain drug concentration,