This blog post was co-authored with Dr. Mary Rose Pambid, Clinical Research Manager at Phoenix Molecular Designs

Triple Negative Breast Cancer (TNBC) occurs when the most common cell receptor types for fueling breast cancer growth are absent from tumors. This absence results in the inability to treat this type of breast cancer with common means, such as hormone therapy and various drugs. One treatment option you may be familiar with is immunotherapy, which stimulates the immune system with proteins and other elements to combat the spread of cancer cells. 

Immunotherapy is a treatment that has recently been approved for breast cancer. However, breast cancer is an umbrella term, carrying with it the weight of various subcategories of cancer cells. What’s more, therapies for one type of cancer are not always effective at treating other types. 

Recently, the pharmaceutical research company Merck and Co., Inc. announced a speed bump in its TNBC treatment clinical trials. Merck and Co.’s landmark immunotherapy drug Keytruda failed to reach an established endpoint in treating patients for metastatic TNBC. The hope was that Keytruda would prove itself a viable treatment option for the aggressive cancer. Unfortunately, this was not the case, and the study has shifted its focus to combined Keytruda and chemotherapy treatment of earlier-stage breast cancer.

Part of this disappointment stems from Keytruda’s prior success in treating metastatic melanoma, an aggressive variant of skin cancer. Studies from 2018 demonstrated the influence Keytruda has over the most advanced stages of melanoma. Of particular note was the overall survival rate of 32.7 months for patients, which doubled that of competitor drug Yervoy. The thought was: if the immunotherapeutic drug can treat an aggressive skin cancer, could it work on an equally-aggressive breast cancer? 

Despite great efforts, the study proves that immunotherapy is not necessarily the best treatment for breast cancer in general. 

That’s not to say all hope is lost for those diagnosed with TNBC. Combinations of PD-L1 blocking supplemented with the chemotherapeutic drug paclitaxel have worked in a small subset of TNBC patients. While not a home run, this is certainly a sign of positive progress.

As research into breast cancer therapeutics continues, especially for a cancer as aggressive as TNBC, researchers and patients must keep a few things in mind:

  1. There is no end-all, be-all treatment option for cancers.
  2. Every cancer diagnosis is different.
  3. While plenty of progress has been made in breast cancer treatment, there are still miles to go before we sleep.

Cancer research as a whole is a field that continues to grow. As biotechnicians and researchers discover more methods of treating cancer, we still must be wary of new developments in cancer itself. Cancer is the sickness that never sleeps, so we won’t, either!