New Approach to Treating Triple-Negative Breast Cancer
Breast cancer is the most commonly diagnosed cancer in women except for non-melanoma skin cancers. Triple-negative breast cancer is a type of breast cancer that represents 10-20% of cases. Triple-negative is considered a more aggressive type of breast cancer generally with a poorer prognosis.
Triple-negative breast cancer
Triple-negative breast cancer cells test negative for estrogen receptors, progesterone receptors, and excess HER2 proteins. This means that cancer cell growth is not driven by estrogen, progesterone hormones, or by HER2 proteins. Thus, there is no curative response to the more numerous, traditional breast cancer drugs or hormone therapy approaches used in most cases.1
The importance of understanding breast cancer subtypes is that treatment plans are targeted to impede the growth of the cancer. Scientists have been looking to identify new kinds of medications that interfere with the spread of triple-negative breast cancer.1
New research findings for triple-negative breast cancer
Findings from the Moffitt Cancer Center in Tampa, Florida, presented at the 2019 American Association for Cancer Research (AACR) meeting, suggested that treatment with T-VEC (talimogene laherparepvec) was associated with an improved prognosis.2 This small study of patients with triple-negative breast tumors revealed that adding an oncolytic virus (one that kills cancer), developed from the herpes simplex virus, talimogene laherparepvec (T-VEC, Imlygic) to neoadjuvant chemotherapy (chemotherapy that is administered before any surgery) resulted in pathologic complete response (pCR).2,3 Definitions for pCR vary. It is used as a tool to evaluate the effectiveness of neoadjuvant treatment by examining tissue removed during surgery to determine if there are active cancer cells. If there are none present, it is considered a “pathologic complete response,” defined in this study as the presence of no invasive disease in the breast or lymph nodes.2 The study examined the effect of adding an oncolytic virus to neoadjuvant chemotherapy to see if there was an improvement to pCR by tumor cell lysis (the killing of cancer cells) and induction of an antitumor response. This brings about an anticancer immune response that may help control cancer growth after chemotherapy.3 The investigators support that the antitumor response “attacks the primary tumor but may also have the potential to spread systemically to improve host surveillance and possibly eradicate the micrometastatic disease.”3
Improved response to treatment
According to study investigator Dr. Hatem Soliman, this treatment regimen resulted in an increase in both disease-free survival and overall survival. Five of the 9 patients in the study achieved pCR. Four additional patients had small residual foci, or activity. This created an improved prognosis and reduced likelihood of recurrence, say study authors.2 There was no dose-limiting toxicities from this treatment. The most common side effects were fever, injection site reaction, and chills. A few serious adverse events were noted. They included pulmonary embolism, severe postoperative brachycardia, and one case of latent genital herpes reactivation. The researchers noted that a single-arm phase II study is presently actively recruiting patients to further evaluate the regimen’s efficacy and to assess immune correlates- evidence of being protected against becoming infected and/or developing additional disease.2,3
Internal radiation therapy is the most common type of radiation used to treat breast cancer.