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Dr. Arenson Comments on Brain Tumor Treatment

Posted by Edward Arenson.M.D. on August 15, 2013 at 1:10 PM

  At the recent meeting of the American Society for Clinical Oncology, major presentations were made of two studies which sought to determine if the addition of bevacizumab (Avastin) (BEV) to standard treatment with temozolomide (TMZ) would improve time to relapse and/or overral survival in newly diagnosed glioblastoma multiforme (GBM). Neither showed significant improvement in overall survival, while one of the two showed improved time to relapse. These studies also differed on the effect of BEV on quality of life. Here are some thoughts on how we should interpret these studies.  Please keep in mind that that BEV is FDA approved for use in recurrent GBM.

  Study RTOG 0825, presented by Dr. Mark Gilbert from MD Anderson, analyzed 673 patients and found, as expected, that 33% of patients were predicted to be responsive to TMZ, while 67% were not.  Approximately 50% of each group received BEV in addition to TMZ while the rest received infusions of salt water.  Thus, there were four groups of patients: 105 who might benefit from both TMZ and BEV, 105 who might benefit from TMZ alone, 213 patients who might benefit only from BEV, and 213 who were unlikely to benefit from their treatment at all.  According to my calculations, only 16% of patients really tested the question of whether BEV could inprove upon TMZ alone. Dr. Gilbert states emphatically that none of these groups could be shown to benefit from BEV in overall survival, while there was better relap-free survival for patients who received BEV, but this benefit did not reach statistical significance.  If we assume that those who derived the most benefit from BEV comprised only 16% of the total, it is easy to see how the wrong conclusion could be reached that BEV is not beneficial in GBM.  A study of 637 patients seems on the surface to be more than enough to test the hypothesis of whether or not BEV is beneficial, but, as I believe this analysis shows, only a small subset could be expected to benefit.  In my opinion, this susbset is too small to be conclusive. Perhaps this is one explanation for why the other study. AVAglio, did show benefit even though it was nearly identical to RTOG 0825.

  Since BEV is the only new treatment shown to have efficacy in GBM in more than a decade, it would be a shame to exclude its use, at least for selected patients with newly diagnosed GBM, based on a study which, I believe, was flawed and from which the wrong conclusions have been drawn.  This is especially true for patients with large unresectable tumors who are expected to do poorly, frequently suffer the devastating effects of dexamethasone dependency, and are often excluded from this type of study.

  Another presentation at the same meeting concerned the use of either TMz or irinotecan (CPT-11) with BEV for newly diagnosed patients predicted to be resistant to TMZ. It was shown that the combination of CPT-11 and BEV had superior outcomes. In our program, we use BOTH CPT-11 and TMZ in order to compensate for those patients whose tumors are less responsive to TMZ.  Our results (please see Results http/www.braintumorhope.net) are superior to standard therapy.

Edward B. Arenson, M.D.

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1 Comment

Reply Ana Aitawa
5:55 AM on November 17, 2017 
Global Glioblastoma multiforme drugs market by drug types (Bevacizumab, Temozolomide, Carmustine) to reach nearly $890 Million in 2021, at a CAGR of 13.4% from 2017 to 2021 - iHealthcareAnalyst, Inc.