HER2 Two

I met a charming patient in my office this week. A gentleman with advanced gastric cancer. Upon further examination of his cancer, the adenocarcinoma cells were found to be strongly positive for human epidermal growth factor receptor 2 (HER2).

Many of my readers are familiar with this surface receptor, a member of the epidermal growth factor family. It’s discovery, and the subsequent development of treatments directed toward this target, are well described in the literature. While most people are familiar with this protein in breast cancer, it is only in the last several years that we have recognized the importance of HER2 expression in diseases like gastric and esophageal cancer.

Discussing the implications with the patient and his sons, I realized that this attractive therapeutic target might not be available for use due to the patient’s underlying heart disease. One of the toxicities of HER2-targeted therapies is congestive heart failure. As I pondered the dilemma, I was reminded of one of my patients from 16 years earlier.

At that time, a strapping 69-year-old woman arrived in my office with a large, high-grade breast cancer and 13 positive lymph nodes. She was also HER2 positive. The problem was that in 1997, the drug trastuzumab was not widely available and never (not ever), used in the adjuvant setting. With that as a backdrop, I treated the patient based on laboratory analysis using the best combinations I could identify. Now, 16 years later, still free of disease, she represents a rare success for someone afflicted with such aggressive (and yes, HER2-positive) disease.

The reason this former patient came to mind was that her excellent success 16 years earlier had not required the use of HER2-directed therapy. Ingrid Ottesen had done very well using assay-directed therapy chemotherapy without the addition of trastuzumab.  All we needed for Ingrid was the best use of available drugs. Despite the possible contraindication for trastuzumab in this gentleman’s case, we can still hope for a good outcome if we use the available drugs that best meet his need. After all, it worked perfectly for Ingrid.

You can read about Ingrid in Chapter 14 in Outliving Cancer, to be released later this month.FINAL book cover-lo res

Targeted Therapies — The Next Chapter

Within this blog, we have intermittently reviewed the concept of targeted therapies. To reiterate, these are classes of drugs that target specific pathways considered tumorigenic. Among the pathways initially targeted were the epidermal growth factor receptor and the closely related HER2. Shortly after the introduction of EGFr and HER2 directed therapies came the development of drugs that target another critical pathway, mTOR.

Hundreds of compounds are now under development intended to more accurately hone in on the pathways of interest in patients’ tumors. Regrettably, the medical community continues to apply old clinical trial methods to this newest era of drugs. While the selective application of drugs like: Tarceva for EGFR mutants, Herceptin for HER2 over-expressers, and Crizotinib for EML4-ALK mutants, are much more effective in patients with these gene expressions, these are a select few examples of linear thinking that bore fruit.

That is, this gene is associated with this disease state and can be treated with this drug.

Many, if not most cancers will prove to be demonstrably more complicated. Genomic trials can only succeed if we first know the gene of interest and second know that its (over) expression alone is pathogenetic for the disease entity. Even meeting these conditions is likely to result in comparatively brief partial responses due to the crosstalk, redundancy and complexity of human tumor signaling pathways — the “targets” of these new drugs.

To address these complexities, functional analytic platforms that examine outcomes, not targets, are needed. This bottom-up approach has now enabled my team to explore the activity of novel compounds. When investigators develop interesting “small molecules,” we examine the disease specificity, combinatorial potential and sequence dependence of these compounds in short-term cultures to provide meaningful insights that can then be addressed on genomic and proteomic platforms. This reduces the time required to take these new agents from bench to bedside. We cannot solve tomorrow’s questions using yesterday’s mindsets

Emerging Therapies in Breast Cancer: a Focus on Triple Negative Disease

As our understanding of breast cancer biology continues to advance, this disease has come to be understood as many different diseases. Original categorizations based on histology lead to lobular versus ductal subtypes. Thereafter, recognition of estrogen and progesterone status, and finally HER2 status provided further subcategorizations. Over the past decade, molecular subtypes have characterized this disease into a series of signatures characterized by luminal, basal and other groupings with distinct prognoses. Within the context of these categories, the triple negative breast cancers have emerged as an important target. These patients whose tumors do not mark for estrogen, progesterone, or HER2 on immunohistochemical or FISH analyses, appear to carry features that segregate them into a BRCA1-like biology. This is of great interest clinically for it offers the opportunity to treat these patients with drugs found active in the BRCA mutant populations. Among the most active drugs in these patients are the PARP inhibitors. The excellent results with PARP inhibitors and BRCA mutants have been followed by striking response and survival data combining PARP inhibitors with carbo-platinum and gemcitabine. PARP inhibitors by inhibiting DNA damage response can enhance the effects of ionizing radiation, mustard alkylators, topoisomerase inhibitors, platins, and intercalating agents. We have explored the biology of PARP inhibitors in breast and other cancers. In these investigations, our lab to applies the EVA-PCD™ platform to understand how PARP inhibitors enhance the effects of drugs and drug combinations. To date, we have observed good activity for the PARP inhibitors as single agents in BRCA1 positive patients, and in some triple negative patients. More interesting, will be the results combining the PARP inhibitors with mustard alkylators, platins, and drug combinations to optimize PARP inhibitor combinations. This work is ongoing in triple negative and BRCA positive patients as well as other tumor types where the PARP inhibitors may prove useful in the future.