Hello. I am sorry to hear about your mom’s diagnosis. Lung cancer is a disease that grows quietly and is often discovered because of symptoms unrelated to the lungs. It is usually a huge shock. I am also a “mutant” with a Stage 1 NSCLC Adenocarcinoma with an EGFR Exon 19 deletion. Like Lexi mine was caught early enough and was able to be treated with surgery. I won’t have any follow up treatment. The EGFR exon 20 mutation is one of the rarer mutations. I do believe that the current TKI treatments, which Tagrisso is one, have been found to be ineffective with the exon 20 mutation. I do believe there is a new TKI drug being developed called TAS6417. This is all information you should consult with your doctor on. Like Michelle said, research and treatments are moving quickly. I found this link on TAS6417 https://www.biospace.com/article/releases/taiho-pharmaceutical-and-cullinan-oncology-establish-collaboration-to-develop-tas6417-novel-egfr-tyrosine-kinase-inhibitor/
I’m glad you found this site (but sorry you had to), check back with questions and updates when you need to.