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Single-Agent Erbitux Studies in NSCLC
Yesterday I reviewed a series of studies of the EGFR monoclonal antibody cetixumab, or Erbitux, combined with chemotherapy. Overall, these trials are modestly encouraging, without what I would consider to be a potential antagonistic effect when chemo and EGFR tyrosine kinase inhibitors (TKIs) like Iressa or Tarceva. However, we still don’t have studies big enough to establish any role for erbitux. Today, I’ll cover the very limited experience of single-agent Erbitux in advanced NSCLC. Continue reading
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
Never-Smokers, Part II: Different Responses to Treatment
I reviewed some of the differences in the biology and clinical behavior of never-smoker lung cancers vs. the much more common lung cancer seen in current or former smokers. The main reason it is worth discussing is that there appear to be important differences in how never-smokers with NSCLC respond to some treatments, particularly EGFR tyrosine inhibitors like Tarceva, or Iressa previously. Among the first reports of this came from Memorial Sloan Kettering Cancer Center in NYC, which reviewed their experience with single-agent iressa several years ago and found that never-smokers were much more likely to demonstrate a significant response to iressa than current or former smokers (36% vs. 8% response rate, shrinking the cancer by 50% or more of the total measured volume). Along with bronchioloalveolar carcinoma histology, smoking status was among the most important variables in predicting response to iressa (abstract here).
As we learned about EGFR receptor mutations, first described in 2004 and associated with a high likelihood of response to EGFR inhibitors, we got some explanation for why never-smokers seemed to do well. In fact, the initial report by Dr. Lynch in the New England Journal of Medicine described 9 patients with excellent responses to gefitinib, of whom 6 were never-smokers. A study of tumor tissue out of Memorial Sloan Kettering showed that 7 of 15 lung tumors from never-smokers carried an EGFR mutation, compared with only 4 of 81 from smokers. Another study of patients who had surgery for early stage lung cancer in Japan showed that among 154 resected tumors (36% were from never-smokers, really highlighting how common never-smoker lung cancer is in Japan!). Since then, multiple trials have shown that never-smokers are significantly more likely to have EGFR mutations than smokers, and are also significantly less likely to have mutations in the gene k-ras (rhymes with mass) that in study after study are associated with no benefit from EGFR inhibitors. There are many controversial issues in lung cancer, but this is not one of them. From all over the world, the studies all show the same thing. Continue reading
Erlotinib (Tarceva) in Previously Treated NSCLC
In a recent post, I described the approval of taxotere as a second-line chemotherapy with a modest but survival benefit for patients previously treated with one line of chemo, usually a platinum-based doublet. Two years ago, erlotinib/tarceva, an inhibitor of a target on many NSCLC tumors called the epidermal growth factor receptor, was approved by the FDA as an additional treatment option for previously treated patients with advanced NSCLC, based on a large randomized clinical trial led by the National Cancer Institute of Canada that was published in the New England Journal of Medicine (BR.21 abstract here), demonstrating the importance of the results.
(Click to enlarge picture)
Clinical Trial Focus: RADIANT Trial in Adjuvant NSCLC
As described in a prior post, chemotherapy after surgery is often recommended after surgery, at least for a subset of patients with stage IB to IIIA (without mediastinal lymph node involvement) NSCLC, based on a potential to increase cure long-term survival compared to surgery alone. At this point, two forms of targeted therapy (erlotinib, or Tarceva, as a single agent in second- and third-line advanced NSCLC, and bevacizumab, or Avastin, combined with carboplatin and paclitaxel for first-line treatment of advanced NSCLC) have been approved by the FDA for advanced NSCLC because they have demonstrated an improvement in survival. At this point, however, we don’t know whether adding targeted therapies as a strategy in earlier stage NSCLC can increase cure rates. But one key trial that is evaluating this possibility is the RADIANT trial.
RADIANT Trial; click to enlarge.
RADIANT is an acronym for Randomized, Double-Blind Trial in Adjuvant NSCLC with Tarceva. This will be an international trial designed to enroll 945 patients who have undergone surgery, with no residual cancer left behind, for stage IB, II, or stage IIIA NSCLC. Patients may have received up to four cycles of chemotherapy after surgery, but patients who received no chemo are still eligible. Patients are then randomized to receive either tarceva or a placebo, with two-thirds of patients receiving the active drug and one-third receiving placebo. Because it is a double-blinded study, neither patients nor their treating doctor know who is getting tarceva or a placebo. This is appropriate because we don’t know whether Tarceva is going to be better, the same, or actually worse, with side effects of treatment but no added benefit.
Importantly, although Tarceva is approved by the FDA for all patients with previously treated advanced NSCLC, regardless of whether their tumor has high levels of EGFR, the target of Tarceva, or amplification of the EGFR gene in tumor cells. We still debate whether Tarceva works best, or perhaps only works at all, in patients with EGFR protein expression as detected by a test called immunohistochemistry (or IHC) or amplification (excess copies) of the EGFR gene by a test called fluorescence in situ hybridization (or FISH). Many trials that are investigating the future role for Tarceva are using more selected populations based on clinical characteristics such as never-smoking or BAC, or molecular characteristics such as EGFR overexpression by IHC, gene amplification by FISH, or presence of an EGFR mutation detected by gene sequencing. Perhaps the benefits of Tarceva can be found to be more pronounced and more consistent if we can identify and treat those patients most likely to do well with it, rather than use a “targeted therapy” unselectively.
Further information about eligibility details and participating centers can be found here.
EGFR Mutations and Acquired Resistance After Responding
Thus far, the vast majority of patients who have an initial response to EGFR tyrosine kinase inhibitors like Iressa and Tarceva will eventually become resistant to them. At this year’s ASCO, our huge annual US-based oncology conference, a report was made by the group at Memorial Sloan Kettering Cancer Center (Riely abstract here) on a small series of patients who had progressed after a prolonged period of responding to Iressa or Tarceva. They found that patients who had slow progression, generally without symptoms, and then came off of their EGFR TKI therapy would often experience a rapid worsening of symptoms.
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