Guardant 360 results

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Guardant 360 results

Hi, I hope someone from this great community can help. My mom was diagnosed with Stage 4 NSCLC 3.5 years ago. At the time of diagnosis she tested positive for EGFR l858r and was subsequently put on Tarceva which lasted a little over a year before she progressed. Went on Tagrisso for about 1.5 years. She recently tried carbo/alimpta/Keytruda but discontinued in March this year since she was still progressing after 3 rounds. She’s been back on Tarceva for about a months now. She seemed to have responded after two weeks since her health improved however things have been going in the wrong direction now.

She recently had liquid biopsy and the result showed EGFR, TP53, T790m, and RB1. What does this mean? Google keeps turning up SCLC transformation. At this point does her liquid biopsy indicate a need to change treatment? 


JanineT Forum M...
Hi John, Welcome to Grace.  I

Hi John,


Welcome to Grace.  I'm sorry to know your mom is going through this.  I know how difficult it was for me to see my mom become so fragile and to want her back to normal. 


The info from the testing doesn't suggest your mom's cancer has transformed but it does suggest it might.  The results of rb1 and tp53 really don't inform the direction of treatment options.  Unfortunately, the little that is known suggests that the cancer is less reactive to treatment so outcomes tend to be lower.  It's important to remember this information is new to researchers and allows a beginning understanding of what it means but less understanding of what to do with the info.    Even if the cancer does transform her remaining chemo options can be efficacious whether nsclc or sclc single agent chemos such as etoposide, irinotecan, topotecan, paclitaxel.  Another thought that is maybe the most difficult is it may help inform your mom about when to stop anticancer treatment and focus solely on comfort care.  


From ASCO Pubs"Conclusions: RB1 mutation is present in a minority of patients with advanced NSCLC and is associated with poor prognosis. In contrast, RB1 mutation is present in the majority of SCLC patients and is associated with a favorable prognosis." 


Notice the careful wording in the quote from asco, "may potentially" which means there's reason to look further into a possible connection between TP 53 in nsclc to transform into sclc but certainly is conclusive.  From ASCO Pubs, "Conclusion: The presence of TP53 and other coexisting MTs in EGFR MT NSCLC were associated with inferior OS, including patients with emergent T790M MT. An increase in TP53mutation allelic fraction may potentially be a useful clinical predictor of small-cell transformation."


I wish I had better more specific info to share.

All the best hopes to you, your family and your mom,