Barriers in Treating Pancreatic Adenocarcinoma
Some of the difficulties in managing PADC are as follows:
+ Silent Onset and Late Detection - The disease begins with no or minimal symptoms that can go unnoticed until advanced stages. This makes early diagnosis and treatment difficult.
+ Dense Stroma - Tumor associated matrix or stroma is very dense and desmoplastic in nature which hampers drug penetration in to tumor.
+ Vascular Collapse - There is also less blood flow within tumor and this restricts diffusion of therapeutic agents.
+ Drug Resistance - It is firmly established that pancreatic cancer cells are highly chemo- and radiation resistant.
How Nanomedicine Can Address these Challenges?
Nanomedicine is attributed to nanoparticles which are small carriers capable of being programmed to bear drugs to desired cell in a body. These nanoparticles offer several advantages in treating PADC such as:
+ EPR Effect - Due to EPR effect which includes increased permeability and retention, nanoparticles can be successfully delivered to tumor site.
+ Targeted Delivery - Nanoparticles can be surface-engineered with ligands that bind to specific receptors on cancer cells. This promotes drug delivery process and also minimizes negative impacts of drugs on rest of the body.
+ Overcoming Stromal Barriers - Certain nanomedicines can be engineered to penetrate tumor stroma thus, facilitating drug delivery to centre of tumor.
+ Combination Therapy - Nanoparticles can co-encapsulate therapeutic drugs with imaging agents that enable theranostic approaches for treatment and monitoring.
Nanomedicine Strategies for Modulating Tumor Microenvironment
Some strategies have been adopted in order to deal with barriers exhibited by PADC model microenvironment. One approach involves stroma depletion through delivery of pegylated hyaluronidase (PEGPH2O), which has shown to enhance drug accumulation in pancreatic tumors.
Another one aims at inhibition of signaling pathways that is responsible for deposition of stroma like Hedgehog (Hh) signaling to enhance nanoparticle uptake in tumors. Nonetheless, there is literature evidence that stroma depletion may positively contribute to cancer cell proliferation and metastatic process, which makes it rather sceptical when used.
Alternatively, reprogramming pancreatic stellate cells to maintain fibrotic stromal homeostasis offers a promising avenue. For instance, nanoparticles co-loaded with all-trans retinoic acid (ATRA) and HSP47-siRNA have demonstrated significant tumor suppression by normalizing desmoplastic stroma.
Smart Nanomedicines for Targeted Therapy
Several nanoparticle systems have been developed that are smart enough to monitor environmental or external stimuli. These systems provide a response in terms of drug ejection at tumor site itself. They are tailor-made for release of their payload under conditions such as changes in pH, temperature shifts, or by external irradiation.
For example, a temperature-triggered drug release has been achieved using thermosensitive hybrid nanoparticles, significantly enhancing anti-cancer activity when combined with laser irradiation.
Gold nanoparticles stimulated with radiofrequency irradiation have also shown promise in inducing localized hyperthermia, effectively reducing tumor size with minimal side effects. Such optimal releasing nanomedicine enhances drug deposition and at same time reduces toxicity to other adjacent healthy tissues.
Theranostic Nanoparticles for Imaging and Therapy
Theranostics nanoparticles are used in disease therapy and diagnosis since they combine treatment and monitoring processes in a single procedure. For instance, nanoparticles encapsulating indocyanine green (ICG) allow for near-infrared fluorescence imaging, enhancing visualization of infiltrating tumors.
Likewise, integrating magnetic resonance imaging (MRI) with other anti-cancer drugs such as doxorubicin allows tracking and treating PADC selectively. Application-specific nanocarriers and multifunctional nanoparticles will be useful in imaging as well as in therapy to induce heat for hyperthermic treatment.
Single-walled carbon nanotubes, which can convert heat upon near-infrared irradiation, offer another innovative solution for imaging-guided cytotoxic photothermal therapy.
Outlook
There is a lot of promise that nanomedicine can improve prospects of prognosis in patients anewly diagnosed with PADC. As earlier noted, the application of nanoparticles takes advantage of their ability to home in to areas that harbors tumors. Thus, early diagnosis of pancreatic cancer along with efficient treatments could be realized.
Therefore, future studies should aim at, firstly, standardising protocols and, secondly, discussing local delivery modalities so as to decrease unwanted effects and improve outcomes of treatment. As more nanomedicine formulations reach clinical approval, they may revolutionize approach to combating this deadly disease.
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