Breast cancer remains one of the most common cancers among American women today, resulting in nearly 40,000 deaths annually.

However, the incidence of breast cancer cases has steadily declined since 2000, thanks to the decreased use of hormone therapy, which was implicated in a higher risk of breast cancer and heart disease. In addition, targeted treatments for breast cancer have improved dramatically, helping even late-stage patients achieve a five-year survival rate of 22%.

That's not to say, however, that breast cancer treatments are anywhere near ideal. Most treatments are still administered along with chemotherapy, which wipes out healthy and cancerous cells together, resulting in gastrointestinal problems, hair loss, and extreme fatigue.

Yet looking ahead into 2014, several companies -- such as Galena Biopharma (NASDAQ:GALE), Merrimack Pharmaceuticals (NASDAQ:MACK), and Pfizer (NYSE:PFE) -- could introduce new ways to treat breast cancer that could substantially improve the lives of patients and shake up the market traditionally dominated by oncology giant Roche (NASDAQOTH:RHHBY).

Understanding the types of breast cancer
In modern breast cancer treatments, three types of cancers are frequently discussed -- ER positive (cancers that grow in response to the hormone estrogen), PR positive (which grow in response to another hormone, progesterone), and HER2 positive (which overexpress a protein known as HER2/neu).

Type of breast cancer

Percentage affected

Dominant treatment(s)

ER positive

75% of all breast cancers

Tamoxifen, aromatase inhibitors

PR positive

65% of ER positive cases

Tamoxifen, aromatase inhibitors

HER2 positive

20% of all breast cancers

Herceptin, Kadcyla, Tykerb


As long as patients have one of these positive gene expressions, the cancer becomes easier to treat with targeted treatments. Patients with HER2 positive breast cancer currently have the most targeted treatment options, whereas ER and PR positive patients mostly rely on hormone therapies like Tamoxifen.

On the other hand, a cancer with does not exhibit ER, PR, or HER2 positive gene expressions is known as "triple-negative", which affects 10% to 20% of all patients.

In addition to being harder to treat, due to the lack of gene expression markers, triple-negative breast cancer is also more aggressive. Triple-negative breast cancer is usually treated with surgery, radiation therapy, and chemotherapy instead of targeted treatments.

Galena's breast cancer vaccine
Galena's NeuVax, which is commonly called the "breast cancer vaccine", has gained a lot of attention for its ability to stop recurrences of certain types of breast cancer.

NeuVax is an immunotherapy treatment which stimulates a patient's immune system to identify and destroy residual cancer cells in patients who have achieved remission. There is currently a 15% to 20% chance of breast cancer recurring after remission, even in patients who have undergone a mastectomy (breast removal).

Neuvax is currently being tested for four indications, with its indication for node-positive breast cancer being the closest to a market approval.

Neuvax Indication


Node-positive breast cancer

Phase 3, in progress

Node-negative breast cancer

Phase 2, complete

HER2 breast cancer (with Herceptin)

Phase 2, in progress

Prostate cancer

Phase 1, complete

Source: Company website.

NeuVax's HER2 indication actually targets lower to intermediate levels of HER2 expression, which would allow it to reach a larger patient group than Roche's Herceptin, the most widely used treatment for HER2 positive breast cancers.

If NeuVax is approved for its breast cancer indications, it could evolve into a blockbuster drug with peak sales potential of $2.5 billion to $5 billion.

Galena has major backers -- Teva Pharmaceutical (NYSE:TEVA) signed an agreement with the company last December to commercialize Neuvax in Israel, and Dr. Reddy's Laboratories (NYSE: RDY) recently agreed to commercialize NeuVax in India. Both collaborations will yield milestone and royalty payments in the future.

Merrimack's new treatment could reach a larger group of patients
Meanwhile, Merrimack's experimental breast cancer drug MM-121 could eventually reach a much larger patient group than Roche's Herceptin.

MM-121, which is being developed with Sanofi, is the first fully human monoclonal antibody which targets a cell surface receptor known as HER3 (ErbB3), which can be found in ER and PR positive breast cancers. The drug is being tested with Exemestane, a hormone therapy for post-menopausal women, against a treatment of Exemestane alone.

Initial results from a phase 2 trial have been positive but incomplete, with favorable overall survival data for the MM-121 arm being recorded in 25% of patients so far. Another study is currently comparing a treatment of MM-121 with the chemotherapy drug Paclitaxel followed by doses of the cancer drugs doxorubicin and cyclophosphamide, versus a treatment of Paclitaxel alone followed by the same two drugs.

Although it might be too early to call MM-121 a "game changer", its potential to treat a much larger base of breast cancer patients compared to Herceptin (75% compared to 20%) can't be ignored.

Therefore, analysts believe that MM-121 could hit peak sales of $1.3 billion from U.S. sales alone if approved -- which would be a huge boost for a company which only reported revenues of $48.9 million last year.

Pfizer leads the CDK revolution
Last but not least, Pfizer's CDK (cyclin dependent kinases) inhibitor palbociclib could herald a new generation of breast cancer treatments. CDKs are enzymes which regulate cell division; when they become overactive or cease to function, cells start proliferating wildly and cause various types of cancer.

Pfizer believes that targeting two specific types of CDK -- 4 and 6 -- could shut down that unregulated cell division. Pfizer's palbociclib targets HER2 negative and ER positive breast cancer -- which means it could potentially reach 75% of all breast cancer patients.

Considering palbociclib's game-changing potential, the FDA granted the drug a breakthrough therapy designation last April, putting it on track to a possible approval by 2015.

Palbociclib is currently in phase 3 trials, and could generate peak sales of $1.9 billion if approved.

Pfizer's strategy, however, hasn't gone unnoticed. Novartis and Eli Lilly are also developing competing CDK 4/6 inhibitors for breast cancer. However, Novartis' LEE011 is just starting phase 3 trials, while Lilly's LY2835219 is being tested for a wider array of indications in phase 1 trials.

The Foolish takeaway
In conclusion, these newer treatments from Galena, Merrimack, and Pfizer are all worth watching closely this year. If these treatments are successful, breast cancer patients could soon be treated with better therapeutic vaccines and targeted treatments, further improving survival rates for a much larger group of patients worldwide.
