Biotech Values

[DewDiligence]

Interesting post from the OSIP board:

This post by ‘thirdmeinvestor’ (#33738) was in reply to my post about the Tarceva monotherapy trial in the U.K. in first-line NSCLC (#msg-4680706).

[Emphasis added by Dew]

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Here they seem to imply that the patients will be selected from pools of inoperable cases and also from chemo-intolerant situations. But oncologists have the option to use radiotherapy (RT). Don't anyone downplay the combination of RT and Tarceva. As I mentioned once before on this board, (I have to mention the mechanism, sorry Dew) EGFR1(HER1) inhibitors arrest cells in the G1 phase of cell cycle and if you receive T continuously for a while all tumor cells would be accumulated in G1. When T is withdrawn for 24-48 hours so, the effect of T disappears, and surviving cells would enter the next phase, DNA synthesis phase all at once. This is the time they should deliver RT because cells in S phase is most sensitive to radiation because RT cuts replicating DNA double helix at many many places and cells cannot repair very well in S phase. You should not take T for a day or two after RT is delivered because again T would arrest cells to allow the time to repair DNA damage. All oncologists know this, but they don't apply the knowledge in trials, most likely because of the constraint imposed on the control patients who should get the best standard care. You may recall ASCO-reported fantastic synergy between Erbitux and RT in treating head & neck tumors. One can devise many interesting treatment options by varying the RT dose and the time interval between successive RT doses, T or E has to be inserted in between. The cell cycles in human tumors are days long, so a weekly schedule of repeating the combo until all tumor cells are killed. Sadly, all trials I read so far administer T everyday. One of the reasons that Chemo + T or Chemo + Iressa did not work is because the patients had taken the pill continuously.
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