Effect of Tagrisso on GGOs in multifocal lung cancer

Question: Has anyone had experience with GGOs (ground glass opacities) turning solid after treatment with Tagrisso? Or any experience in general with GGOs and Tagrisso, especially in multifocal lung cancer, however the GGOs responded to Tagrisso: shrinking/disappearing; unchanged; growing? How long it took to see a response to Tagrisso?

Background: In June of 2024, I started Tagrisso to treat multiple GGOs across three remaining lobes of my lungs, some with a solid component, that had shown growth over time. The upper right and upper left lobes were removed via VAT lobectomies in 2019 and 2021, respectively. I delayed starting Tagrisso because I was asymptomatic and I wanted to delay starting a treatment to which the cancer would eventually become resistant (at the time, a median PFS (progression-free survival) of 18.9 months).

The first scan after starting Tagrisso, in September 2024, showed (1) no new lesions (which had been noted in prior scans); (2) the size of all lesions more or less stable with minor changes; (3) a notable change in appearance from a ground glass/mixed opacity to a more solid appearance. The December 2024 scan showed stability: no apparent growth or shrinkage in the now mostly solid lesions.

Because the lesions changed after starting Tagrisso, but did not change in an expected way, it is not clear that the change is necessarily a reaction to Tagrisso –or perhaps not necessarily a desirable reaction. This raises the question of how long to continue Tagrisso. My next scan is in March; we will assess after each scan.

Note: It is possible that not all lesions have the EGFR exon 21 L858R mutation. Tissue biopsies from the two lobectomies in 2019 and 2021 were positive for EGFR exon 21 L858R mutation. Five lesions sampled via a bronchoscopy in 2022 were positive for EGFR exon 21 L858R mutation or for KRAS mutations (EGFR and KRAS are mutually exclusive). A liquid biopsy was negative for circulating tumor DNA; I have read that multifocal lung cancer rarely yields a positive liquid biopsy. There is no practical way to biopsy all lesions.