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Targeted Therapy for Selected Populations in NSCLC
In my last post, I described the somewhat disappointing results for tarceva compared with chemotherapy in a trial of unselected advanced NSCLC patients with a marginal performance status. However, EGFR tyrosine kinase inhibitors like iressa and tarceva were developed as targeted therapies, so perhaps they might prove to be more effective if used selectively, in a targeted population. That targeting might be based on clinical characteristics like using it in never-smokers or bronchioloalveolar carcinoma (BAC), or it might be based on molecular markers like mutations in the EGFR gene or overexpression of the number of copies of the EGFR gene, as determined by fluorescence in situ hybridization, also known as EGFR FISH testing. All of these methods have been employed in early but very promising studies of iressa or tarceva in selected populations. Continue reading
Targeted Therapy in Older and Sicker Patients: A Replacement for Chemo?
The emergence of targeted therapies provides a goal of treating the cancer more selectively, thereby minimizing side effects, while hopefully achieving results as good as or better than standard chemotherapy. Although this is important in the entire population of cancer patients, this is a particularly welcome benefit in patients who may be reluctant to or not healthy enough to receive standard chemotherapy. As I mentioned in my last post on the association of age and benefits of chemotherapy, chronological age is not nearly as important as performance status, at least up until around age 80, where we have very few patients on clinical trials to help tell us what to expect. Regardless, there have been several studies of tarceva/erlotinib in older patients, and other trials specifically looking at patients with marginal performance status regardless of age, asking whether we can do as well or better with tarceva as with conventional chemotherapy in these patients. Continue reading
Is Rash a Good Thing with EGFR Inhibitors?
An acne-like rash or dry skin is a very common side effect of the drugs that target the epidermal growth factor receptor, with approximately 3/4 of patients who receive the EGFR tyrosine kinase inhbitor tarceva/erlotinib experiencing skin toxicity. Similar skin toxicities are also seen, but a bit less commonly, with the very similar drug iressa/gefitinib, and also frequently with erbitux/cetuximab, a monoclonal antibody that is less well studied in lung cancer. But since the earliest clinical trials of these agents, there have been questions of whether the rash is something more than just a potentially problematic side effect, but rather a marker of someone likely to do well with these agents.
Are EGFR Inhibitors Only Useful in Certain Patient Groups?
Since the earliest clinical trials of EGFR inhibitors in NSCLC, certain clinically defined patient subsets became identified as more likely to show a benefit than others. Such studies suggested that women, patients with adenocarcinomas rather than squamous cell carcinomas, Asian patients, and never-smokers compared with current or former smokers were the patients who would do well with EGFR tyrosine kinase inhibitors like gefitinib (Iressa) or erlotinib (Tarceva). Since that time, we have been debating whether these targeted therapies should be used primarily or exclusively in selected populations or whether they should be used in general lung cancer populations. The correlation of rash with better outcomes is another interesting issue that is a big enough topic I’ll discuss it separately in the near future. Since it’s not something you know about before you start treatment, unlike patient sex race or subtype of lung cancer, it’s a different issue.
EGFR Tyrosine Kinase Inhibitors in Advanced BAC
As we established several years ago that it is indeed possible to do clinical trials with more than 50 or even 100 patients with advanced BAC, we were also seeing that those first forays into advanced BAC with standard chemotherapy were somewhat disappoingting (described further in another post). Fortunately, as it became clearer that we needed other options for advanced BAC, we started to see the first cases of patients with BAC who received Iressa on clinical trials who would sometimes have rapid and profound responses to this drug (below showing a difference after just 5 days):
The lung cancer physicians at Memorial Sloan Kettering Cancer Center (MSKCC) reviewed the results from 139 patients who received the EGFR tyrosine kinase inhibitor (TKI) Iressa (gefitinib) as a single agent over a 5 year period and found that a diagnosis of BAC was among the strongest predictors for having a response to Iressa (abstract here).
Continue reading
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