Of Mice and Cancer: How a relative of smallpox might help cure breast cancer

Vaccinia Virus, Source: Wikimedia Commons

Vaccinia Virus, Source: Wikimedia Commons

This post was originally published at Mind the Science Gap on Oct. 18, 2012.

Just in time for Breast Cancer Awareness Month, the American College of Surgeons issued a press release with a potentially  life-saving finding. Detailed in the press release are the results of a study recently conducted at Memorial Sloan Kettering Cancer Center (MSKCC) where scientists recently conducted a study in mice and found that a new vaccinia virus (named GLV-1h164) can kill Triple Negative Breast Cancer (TNBC) cells.

Vaccinia is a poxvirus, and it is in the same family as smallpox and monkeypox. In fact, vaccinia is the virus used in the smallpox vaccine. The virus in this study works by preventing the tumor from recruiting blood vessels (angiogenesis), a crucial step in cancer spreading. If a tumor can’t recruit blood vessels, then it can’t receive oxygen and nutrients from the blood. This virus effectively starves the tumor.

The Triple Negative of TNBC refers to breast cancers that do not express genes (a process where information from genes is turned into an actual product like a protein) for:

  1. Estrogen receptors – The status of these receptors determines a tumor’s susceptibility to hormonal chemotherapy drugs like tamoxifen. If receptors are present, hormonal treatments can be used in treatment.
  2. Progesterone Receptors – Like estrogen receptors, presence of these receptors indicates a tumor’s susceptibility to hormonal treatments
  3. Human Epidermal Growth Factor Receptor 2 or HER2 – A common target for cancer treatments, since HER2 overexpression leads to aggressive cancers

The fact that this virus might be able to kill TNBC cells is an amazing leap forward, as TNBC is a formidable diagnosis. It is typically is found in young women, women too young for recommended regular mammograms. (This is why a monthly self exam is important!) They’re aggressive cancers, and even after treatment women with TNBC typically relapse. Once TNBC has metastasized (spread to a non-adjacent organ or body part), more than 70% of patients will die within five years.

What’s important to remember is that we can’t declare victory yet. This study was done in mice, which means that while it is promising there are several steps required to establish safety and efficacy in humans before bringing it into regular usage. Mouse studies are a step on the ladder, and the researchers working on this therapy are currently designing what are known as Phase 1 clinical trials. These are trials done in small numbers of people (who have been informed of the risks involved and have decided to take part) to determine safety of the treatment in humans. (Phases 2 through 4 involve developing a testing protocol, final testing, and pre-approval studies.)

This story first popped up on my radar because of the smallpox connection; I’m part of a small percentage of my generation to be vaccinated. But I’m also part of a much larger percentage – I know someone who has survived breast cancer. Treatment is long and arduous, making it difficult for women (and men!) to participate in activities with friends and family. Any cancer diagnosis is a major blow, but new findings bring hope that the road to recovery and remission might be more clear in generations to come.

The White House, lit with pink flood lights for Breast Cancer Awareness Month (C) US Government [Public Domain] via Wikimedia Commons

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