Immunotherapy and beyond: cancer vaccines

This article examines promising new cancer treatments. Immunotherapy is the first to come to mind in recent years: using our immune system to treat cancer. Cancer immunotherapy falls under 3 headings: immune checkpoint inhibitors, cancer vaccines and adoptive T-cell therapies.

The past 20 years have seen discovery, development and use of targeted smart molecules. These drugs transformed oncology and continue to benefit millions. However, the field has completed its development and its success curve has plateaued. Newly discovered immune therapies therefore excited us all. Combinations among these immune-targeted treatments, which we will introduce, and with targeted therapies will undoubtedly advance cancer treatment much further.

Let us review these exciting developments together.

First, cancer vaccines and the latest developments.

Vaccine treatment in cancer

Oncolytic virus vaccines

The main cause of cancer death is cancer cells invading other tissues and organs, called metastasis. Recent research attributes 90 percent of cancer deaths to metastasis. Because treatments for metastatic, fourth-stage cancers fall short of desired success and cause side effects, researchers have pursued new treatments.

Cancer vaccines have gained popularity, with many pharmaceutical companies intensifying research. They can be divided into two groups:

1. Therapeutic vaccines and
2. Preventive cancer vaccines.

Therapeutic vaccines aim to kill cancer cells by generating strong immunity against them or using genetically manipulated viruses. Preventive vaccines create immunity against cancer-causing oncoviruses.

One basic therapeutic-vaccine principle is eliminating cancer cells using viruses. Viruses used to develop these vaccines are called oncolytic viruses . “Oncolytic” means tumor-destroying . These viruses target and destroy only cancer cells. Genetically manipulated viruses cause no harm when entering normal cells.

In cancer cells, however, they enter, multiply and burst the cells, causing death. Many oncolytic vaccines have recently been developed, but most have not progressed from clinical research to routine practice. No single oncolytic vaccine exists for every cancer type. Below are vaccines still under study but expected to gain approval soon.

-Talimogene laherparepvec (T-VEC, OncoVEX): phase-3 studies in melanoma treatment continue.

-Reolysin: phase-3 studies in head and neck cancer continue.

-dl1520 (ONYX-015): phase-3 studies in head and neck cancer continue.

Currently, no oncolytic cancer vaccine has FDA (United States Food and Drug Administration) approval. The main concern is that long-term effects remain unstudied. Recent results are promising, however, and many studies show greater effectiveness with chemotherapy or radiotherapy.

In 2015, a study presented at the American Society of Clinical Oncology (ASCO) meeting offered promising results for recurrent glioblastoma (GBM), the most aggressive brain cancer. In this study, poliovirus was manipulated to target GBM cells. Tumor cells died in recurrent brain cancer patients, and in 24 percent of patients, median survival was 24 months, very good for this disease. More specifically, brain tumor cells were found to have abundant surface Nec5 , a molecule acting as a receptor for poliovirus, which causes polio. Poliovirus recognizes cells carrying Nec5. Scientists considered using greater tumor-cell Nec5 abundance for targeted treatment and tested poliovirus against cancer. However, the virus can also harm central nervous system cells. Genetic techniques can prevent this nervous-system effect before administering manipulated poliovirus. Another major issue is the patient’s immune response against the virus. Recent research aims to make viruses less harmful and reduce immunity against these therapeutic viruses.

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