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I am also interested in learning more about possible intermittent use of Tarceva. My father has been taking 150 mg Tarceva as a first-line treatment for two months now, and his recent CT scan showed some shrinkage of his primary tumor. Since he does not want to do chemotherapy, his treatment options are very limited. With this in mind, he may be willing to experiment with his Tarceva treatment.6 z, S! L! x3 |2 O# X! \
& v! A+ z, B8 x6 h' p2 PHow soon would it be appropriate to initiate intermittent use of Tarceva? If he did try intermittent use, how many weeks on/how many weeks off would he take it?
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" x: M0 M# y" ]: l% ?7 f K) }Could lowering the dose from 150 to 100 mg also delay the development of resistance (assuming the 100 mg dose was sufficient to keep the disease stable)? This doesn't seem like it would help as much since the cancer would still be continuously exposed to the drug, although the concentration would be lower., P2 J% E( d. B8 d: @
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, J& \# ?# u) Y( Q7 LFull disclosure: This is an idea that has never been tested, and I don't know if it has even been done before casually with an individual patient. I just consider it to be a reasonable idea with a compelling rationale. Giving guidelines might suggest that I know how this situation should be managed, but nobody has ever officially recommended or studied this idea yet.
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; v+ m9 i. j% [+ r/ RIf I did pursue such a plan, it would need to be with a well-informed person who understands what we know and what we still don't know. I would be inclined to treat the patient to maximal response and then likely hold treatment but monitor the patient VERY closely (likely recommending to see the patient back in clinic within weeks, and repeating a scan after just a month), as I have heard of cases where there can be a rapid rebound of progression within just weeks after stopping EGFR inhibitors. I would not imagine that treating someone on a lower dose would have the same rationale of reducing the risk of developing resistance, as you indicated. And i would be inclined to restart tarceva as soon as a patient demonstrated clear, clinically meaningful progression, but I can't define exactly what that would be for a particular patient.
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