Tagrisso not working, new mutations? - 1274331

Hi all,

I have been on Tagrisso for 3 months and after 2 scans showing progression on primary tumor and mixed result, my oncologist concluded that Tagrisso is not working for me. I was tested positive for EGFR exon 19 deletion last year and 790M on Feb this year. Rebiopsy from the lung drain to check on MET mutation came back inconclusive since there were not enough cancer cells in the specimen. As a part of research study, my oncologist tested my blood to track the mutation and found that I no longer have 790 mutation.

He then suggested another needle biopsy to get sample from the primary tumor to check if I have small cell and other mutations (especially MET), and postpone chemo for another 2-3 weeks to wait for the results of the biopsy. Clinical trials would then be another option if new mutations are found. I am nervous to wait for another 2-3 weeks. But since my symptoms have not changed much except for minor chest pressure when coughing or deep breathing lately, my oncologist is not worried about waiting a little longer to understand the mutation.

I was wondering if you have similar experience What could be possible reasons Tagrisso is not working for 790M positive patients? do you have experience in choosing between chemo (carbo, alimta, cysplastin) and early stage clinical trials?

Thanks.