3 Potentially Game-Changing Investigational Breast Cancer Drugs That May Soon Be Available

The grim reality of many types of cancer is that after decades of research we're still largely at a loss to explain what causes cancer in the first place and how to slow or stop its proliferation. While therapeutic improvements have been made in a number of cancer types, we're still a long way from reaching the end goal of eradicating cancer.

One area of focus that's receiving a lot of attention, and rightly so, is breast cancer. In 2013, according to the American Cancer Society (link opens PDF), some 232,340 new cases of invasive breast cancer were expected to be diagnosed in women, with an additional 64,640 cases of non-invasive breast cancer.

Also, breast cancer isn't gender-specific, with an estimated 2,240 cases of invasive breast cancer diagnosed in men in 2013. All things considered, though, this is a disease that afflicts women more than twice as often as any other cancer type and is the second-leading cause of cancer-related deaths behind only lung and bronchus cancer.

Source: Centers for Disease Control and Prevention.

Following the World Health Organization's forecast earlier this year that worldwide cancer diagnoses could rise by 57% over the next 20 years, biopharmaceutical companies have tried to respond in a big way with a handful of new drug candidates targeted at specific cancer types. Here are three potentially game-changing investigational breast cancer drugs that could be poised to greatly improve patient quality of life and overall survival if they're approved by the Food and Drug Administration.

Perhaps no investigational therapy packs more potential punch to breast cancer than Pfizer's palbociclib, which is given in combination with Novartis' Femara.

Palbociclib is specifically focused as a first-line treatment for estrogen-receptor positive, HER2-negative, locally advanced or metastatic breast cancer. This is the dominant type of breast cancer and is often found in 60% to 65% of all diagnosed cases.

Source: National Cancer Institute, Wikimedia Commons.

Palbociclib initially turned heads in December 2012 when Pfizer reported an interim analysis of its phase 2 study that showed a better-than-tripling in progression-free survival to 26.1 months as compared to the 7.5 months produced by the control arm of just Femara. Some might call its final phase 2 study results a bit of a letdown, but the PALOMA-1 final results worked out to a progression-free survival of 20.2 months compared to 10.2 months for the control arm, and a non-statistically significant, but nonetheless favorable, median overall survival advantage of 4.2 months (37.5 months compared to 33.3 months for patients in the control group).

Given that palbociclib was granted the breakthrough therapy designation by the FDA last year, Pfizer announced its intentions last month to file a new drug application using data from its PALOMA-1 midstage study. The breakthrough designation is meant to bring game-changing investigational drugs to market faster, and it could wind up earning Pfizer's breast cancer drug a priority review.

If approved, I would suggest it has blockbuster potential within the first 12 months of reaching market, but that, of course, will depend on a number of factors, including pricing of the drug as well as insurer coverage. As of now, I'd opine that palbociclib has a favorable shot of being approved in the first-quarter of 2015 based on its positive trial results.

Sometimes the biggest battles aren't fought against tumor proliferation, but are instead intended to keep cancer from reforming. Galena Biopharma's primary mission with NeuVax, an adjuvant therapy given to patients that have received chemotherapy, is to keep breast cancer from coming back.

Galena's vaccine is part of a new line of investigational cancer therapies known as cancer immunotherapies. Drugs in this class work by enhancing or teaching the body's immune system to recognize specific cancer cells and eradicate them. NeuVax stimulates CD8+ cytotoxic T lymphocytes which are activated and subsequently seek out and destroy HER2-expressing cancer cells.

Source: Galena Biopharma.

In late 2012 Galena released the final results of a five-year phase 2 study involving NeuVax, with the SN-33 (node-positive) study showing that just 5.6% of patients given NeuVax had a recurrence. By comparison, just over one-in-four patients had their cancer return in the control arm. Overall, NeuVax resulted in a cancer recurrence reduction of 78.4%!

Yet the greatest aspect of NeuVax might be patient convenience. No patient enjoys receiving cancer therapy, but over the course of three years patients will only receive a total of 11 NeuVax intradermal injections. If its phase 2 results carry over into its ongoing PRESENT phase 3 trial, then it could allow for greater peace of mind for patients who'll spend less time receiving medical care and more time enjoying life.

One factor to consider here, though, is that Galena is a relatively small company, and historically small biopharmaceuticals have had little success in getting cancer therapies approved by the FDA. The data so far has done the talking, but it's something to consider as a possible investor in this potentially game-changing investigational vaccine. Interim data on NeuVax's PRESENT study should be out sometime next year.

Lastly, ImmunoGen and Roche's antibody-drug conjugate Kadcyla could be prepared to extend patient quality life for those with HER2-positive breast cancers.

Source: Roche.

Kadcyla is already approved by the FDA to treat HER2-positive metastatic breast cancer in patients that have received prior treatment with Herceptin and a taxane chemotherapy. What makes Kadcyla so unique is that it's an antibody-drug conjugate, or ADC. Instead of simply administering a global chemotherapy and eradicating cancerous as well as healthy cells, ADCs are antibodies with a toxin attached (in this case Herceptin) which seek out a specific protein signature given off by HER2-positive cancer cells. Once located, these toxins release from their antibody and focus on the cancer cells. The goal being to reduce healthy cell death and focus the toxic dose of chemotherapy on cancer cells.

So far, the combination of ImmunoGen's ADC technology and Roche's Herceptin appears to be working. In the phase 3 study which gained the pair an approval as a second-line metastatic breast cancer treatment, Kadcyla improved median overall survival by 5.8 months to 30.9 months while boosting the response rate to 43.6% from 30.8% for the control arm, and improving the median duration of response from 6.5 months to 12.6 months. Furthermore, grade 3 adverse events were seen in only 43% of patients in the Kadcyla arm compared to 59% of patients in the control arm.

The next big step for Kadcyla could be moving into the role of first-line HER2-postiive therapy in both metastatic and early stage scenarios. This would open up a world of new patients for ImmunoGen and Roche, but also potentially expose these patients to a more focused therapy with fewer serious side effects (at least based on the EMILIA phase 3 study). Per Roche's mammoth R&D page, results from the metastatic first-line study are expected next year while the early stage breast cancer study may take two or more years since it can be more difficult to establish a comparative pharmaceutical benefit in the early stages of a disease.

With its possible indications set to grow, I would suggest keeping a close eye on Kadcyla's development going forward.

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The article 3 Potentially Game-Changing Investigational Breast Cancer Drugs That May Soon Be Available originally appeared on Fool.com.

Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.The Motley Fool recommends ImmunoGen. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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