Nanomaterials-based photosensitizers and delivery systems for photodynamic cancer therapy

This article provides an update on the global cancer burden using the GLOBOCAN 2020 estimates of cancer incidence and mortality produced by the International Agency for Research on Cancer. Worldwide, an estimated 19.3 million new cancer cases (18.1 million excluding nonmelanoma skin cancer) and almost 10.0 million cancer deaths (9.9 million excluding nonmelanoma skin cancer) occurred in 2020. Female breast cancer has surpassed lung cancer as the most commonly diagnosed cancer, with an estimated 2.3 million new cases (11.7%), followed by lung (11.4%), colorectal (10.0 %), prostate (7.3%), and stomach (5.6%) cancers. Lung cancer remained the leading cause of cancer death, with an estimated 1.8 million deaths (18%), followed by colorectal (9.4%), liver (8.3%), stomach (7.7%), and female breast (6.9%) cancers. Overall incidence was from 2-fold to 3-fold higher in transitioned versus transitioning countries for both sexes, whereas mortality varied <2-fold for men and little for women. Death rates for female breast and cervical cancers, however, were considerably higher in transitioning versus transitioned countries (15.0 vs 12.8 per 100,000 and 12.4 vs 5.2 per 100,000, respectively). The global cancer burden is expected to be 28.4 million cases in 2040, a 47% rise from 2020, with a larger increase in transitioning (64% to 95%) versus transitioned (32% to 56%) countries due to demographic changes, although this may be further exacerbated by increasing risk factors associated with globalization and a growing economy. Efforts to build a sustainable infrastructure for the dissemination of cancer prevention measures and provision of cancer care in transitioning countries is critical for global cancer control.

Albumin is playing an increasing role as a drug carrier in the clinical setting. Principally, three drug delivery technologies can be distinguished: coupling of low-molecular weight drugs to exogenous or endogenous albumin, conjugation with bioactive proteins and encapsulation of drugs into albumin nanoparticles. The accumulation of albumin in solid tumors forms the rationale for developing albumin-based drug delivery systems for tumor targeting. Clinically, a methotrexate-albumin conjugate, an albumin-binding prodrug of doxorubicin, i.e. the (6-maleimido)caproylhydrazone derivative of doxorubicin (DOXO-EMCH), and an albumin paclitaxel nanoparticle (Abraxane) have been evaluated clinically. Abraxane has been approved for treating metastatic breast cancer. An alternative strategy is to bind a therapeutic peptide or protein covalently or physically to albumin to enhance its stability and half-life. This approach has been applied to peptides with antinociceptive, antidiabetes, antitumor or antiviral activity: Levemir, a myristic acid derivative of insulin that binds to the fatty acid binding sites of circulating albumin, has been approved for the treatment of diabetes. Furthermore, Albuferon, a fusion protein of albumin and interferon, is currently being assessed in phase III clinical trials for the treatment of hepatitis C and could become an alternative to pegylated interferon. This review gives an account of the different drug delivery systems which make use of albumin as a drug carrier with a focus on those systems that have reached an advanced stage of preclinical evaluation or that have entered clinical trials.

Of the deaths attributed to cancer, 90% are due to metastasis, and treatments that prevent or cure metastasis remain elusive. Emerging data indicate that hypoxia and the extracellular matrix (ECM) might have crucial roles in metastasis. During tumour evolution, changes in the composition and the overall content of the ECM reflect both its biophysical and biological properties and these strongly influence tumour and stromal cell properties, such as proliferation and motility. Originally thought of as independent contributors to metastatic spread, recent studies have established a direct link between hypoxia and the composition and the organization of the ECM, which suggests a new model in which multiple microenvironmental signals might converge to synergistically influence metastatic outcome.