Final answer:
Epigenetic drugs, like DNA methyltransferase inhibitors and HDAC inhibitors, are designed to reverse the epigenetic silencing of genes, which can include tumor suppressor genes, hence they have potential in cancer treatment. They do not alter the DNA sequence, making epigenetic changes reversible and offering a significant advantage. However, these drugs have not eliminated the need for combination therapy in cancer treatments.
Step-by-step explanation:
First-generation epigenetic drugs have indeed focused on reversing gene silencing, which is often accomplished through mechanisms such as DNA methylation and histone modification. These drugs, such as DNA methyltransferase inhibitors and histone deacetylase (HDAC) inhibitors, aim to reactivate genes that have been inappropriately silenced in cancer cells. Such silenced genes might include tumor suppressor genes, and their reactivation can lead to the inhibition of tumour growth and progression.
One of the main advantages of epigenetic drugs is that they exploit the reversible nature of epigenetic changes. Unlike genetic mutations, epigenetic modifications do not entail changes to the DNA sequence and can be modified by therapeutic agents. Consequently, they hold great promise in cancer therapy as they can potentially restore the normal patterns of gene expression that are often disrupted in cancer cells.
HDAC inhibitors have been utilized in cancer treatment to increase histone acetylation, resulting in a more open chromatin structure and activation of previously silenced genes, including tumor suppressor genes. However, approved epigenetic drugs have not replaced the need for combination therapy in cancer treatment, and they are not standalone cures for many forms of cancer, including various lymphomas.