CASE 1: A 44-year-old Female Diagnosed with Relapsed Stage IV Adenocarcinoma

Jonathan W. Riess, MD, MS: In terms of specific cases, I’ve done this for numerous patients. There are different ways of looking at it now that we have the availability of plasma cell—free DNA, as well as tissue-based molecular testing.

In one case I could think of, I had a patient who was in her mid-40s who was on afatinib for about 11 months and then developed some new small pulmonary nodules. We discussed, “Well, do we think about switching now or do we get a follow-up scan?” because it was hard to tell how much progression there really was. We obtained a follow-up scan a few weeks later, and there was clear progression. And she started to have a little bit of symptoms before being completely asymptomatic. I had ordered cell-free DNA testing initially because she was there in clinic. She was familiar with the test being very active in the lung cancer patient advocacy community, and so we had sent that off. It came back negative for T790M and actually the activating mutation as well, likely a false negative. We proceeded rapidly to get a tissue biopsy and get molecular testing that showed an EGFR T790M mutation. She’s now on osimertinib, doing fantastically well.

Riess case 1:

A 44-year-old female with relapsed stage IV adenocarcinoma.

• This is a 44-year-old female diagnosed with stage IV adenocarcinoma
• Tissue-based mutation testing showed an EGFR mutation with exon 19 deletion
• She was subsequently treated with afatinib
• After 11 months she became mildly symptomatic with small, nonspecific pulmonary nodules
• Follow up CT scan showed growth of the primary lesion
• The patient reported worsening of her cough
• Cell-free DNA testing was ordered and was negative for both the EGFR driver mutation and for T790M
• Subsequent tissue biopsy showed the presence of T790M
• The patient was switched to osimertinib and continues to respond well to therapy with minimal toxicity