Nanotechnology based drug delivery system in cancer therapy

Cancer is a significant public health problem worldwide. The global cancer burden is expected to be 28.4 million cases in 2040. With the advent of technology, there has been significant progress in cancer prognosis, diagnosis, and treatment over the past few decades. However, cancer's multifaceted nature makes it challenging to eliminate it successfully. Besides the multitude of factors leading to its development, there are over 100 types of cancer which makes it very difficult to develop effective and robust treatments.

Conventional treatment methods for cancer include surgery, radiation, and chemotherapy. Although each of these has its strengths, damage to the normal tissues takes place in all these methods. Chemotherapeutic drugs are an effective way to affect tumour cells. However, their low specificity, targeting ability, and induced drug resistance make it difficult to optimize the treatment and lead to side effects. The quest for developing therapeutics with minimal toxicity continues.

For a benign tumour, targeting a drug can be accomplished. However, the treatment is a challenge for advanced metastatic cancers, and nanotechnology has evolved as a light at the end of the tunnel. Nanotechnology offers a way to target the chemotherapeutic drug selectively to the tumour cells and neoplasm with precise targeting, minimal side effects, and enhanced permeability. This can significantly increase the probability of survival of cancer patients.

Nanotechnology utilizes nano-sized carriers to which the chemotherapeutics are conjugated or encapsulated. A wide variety of nanomaterials utilizing organic, inorganic, lipid, or glycan compounds and synthetic polymers are being utilized to develop cancer therapeutics. The passive delivery of such nanotherapeutics depends on defects in the tumour microenvironment, such as increased defective vasculature, which allows nanoparticles (<200 nm) to accumulate in the tumour microenvironment. In the meantime, the poor lymphatic drainage allows them to release the contents. On the other hand, active delivery targets tumour cells via direct interaction between receptors and ligands. Ligands are conjugated on the surface of nanoparticles to target molecules that are overexpressed on cancer cells.

Nanoparticles are generally coated with hydrophilic materials, which increases accumulation in tumours by successfully evading clearance by the immune system. Factors such as pH, heat, or particular chemical availability trigger the drug release, making it a precise way to target cancer. Nanoparticle-based drug delivery has also been shown to be involved in cancer drug resistance reversal. Cancer drug resistance envelops due to the hypoxic tumour microenvironment and overexpression of drug efflux transporters. Nanoparticles targeting these mechanisms can bring about the reversal of multidrug resistance. Much knowledge about nanoparticles has been gained, and a lot is yet to be discovered. Therefore, nanoparticle-based approaches can be utilized for targeted drug delivery to enhance cancer treatment.