Molecular Pathology and Trainees Joint Session

A Case of Metastatic Lung AdenocarcinomaEGFR Mutation Analysis

Ozge HurdoganIstanbul University

Istanbul Faculty of Medicine

Department of Pathology

Istanbul, Turkey

No conflict of interest to declareozgehurdogan@gmail.com

Case Summary

• 57 y, Female

• Bone pain

• Radiology;• lung mass

• metastatic tumors in bones, liver and brain

Case Summary

• Transthoracic needle biopsy: Primary lung adenocarcinoma

• EGFR mutation analysis: Wild-type• Performed at another hospital

Treatment

• Six-cycle course of chemotherapy• Bone and liver metastases regressed• Lung and brain metastases remained stable

• After 2 months;• Progression in lung and brain masses• Radiotherapy for brain metastases

• After 4 months;• Liver metastases reoccured

CK7 Napsin A TTF-1

Mutation Analysis

• EGFR mutation analysis• Allele-specific real-time PCR

• Cobas® EGFR Mutation Test v2

• L858R mutation detected on liver biopsy

• Erlotinib treatment for 1 year• Lung lesion and metastases regressed

• Tumor markers in blood returned back to normal

• One year later, new brain lesions developed

• CSF puncture performed

MGG

MGG

Napsin ATTF-1

Mutation Analysis

• EGFR mutation analysis on CSF glass slides• Allele-specific real-time PCR

• Cobas® EGFR Mutation Test v2

• Synchronous EGFR mutation analysis on plasma cfDNA• Cobas® cfDNA sample preparation kit

• Cobas® EGFR Mutation Test v2

• EGFR L858R mutation in CSF, as in the liver metastasis

• EGFR T790M mutation positive in cfDNA from synchronous plasma →resistance mechanism

• Erlotinib switched to osimertinib• Brain metastases showed complete response

• Negative CSF puncture after 5 months

Bubendorf et al. Eur Respir Rev 2017;26:170003

Which material is suitable for mutation analysis?

• Tumor tissue (FFPE)

• Cytology • stained/unstained slides

• cell block

• FNA

• exfoliative cytology

• effusion

Lindeman et al. Arch Pathol Lab Med. 2018 Mar;142(3):321-346.

CSF among cytological materials?

Frankel et al. Clin Chem Lab Med 2018;56(5):851–856

OUR CASESummary of EGFR Mutation Analyses

Test Sample EGFR Mutation

Primary tumor WT (Methodology N/A, Tumor content N/A)(outside lab)

Liver metastasis p.L858R

CSF p.L858R

cfDNA p.T790M

OUR CASESummary of EGFR Mutation Analyses

Test Sample EGFR Mutation

Primary tumor WT (Methodology N/A, Tumor content N/A)(outside lab)

Liver metastasis p.L858R

CSF p.L858R

cfDNA p.T790M

Lowes et al. Int J Mol Sci. 2016 Sep 8;17(9).

Liquid biopsy

Liquid Biopsy vs CSF

Zhao et al. Cancer Chemother Pharmacol. 2016 Dec;78(6):1305-1310.

Discordance Between Liquid Bx & CSF

• Poor TKI exposure in CNS • not sufficient to drive overgrowth of the T790M-mediated resistant tumor

cells?

• Tm cells migrated into CNS before T790M mutation was induced?

• The existence of other specific resistance mechanisms in CNS?

OUR CASESummary of EGFR Mutation Analyses

Test Sample EGFR Mutation

Primary tumor WT (Methodology N/A, Tumor content N/A)(outside lab)

Liver metastasis p.L858R

CSF p.L858R

cfDNA p.T790M

OUR CASESummary of EGFR Mutation Analyses

Test Sample EGFR Mutation

Primary tumor WT (Methodology N/A, Tumor content N/A)(outside lab)

Liver metastasis p.L858R

CSF p.L858R

cfDNA p.T790M

Mutation Heterogeneity

Dagogo-Jack et al. Nat Rev Clin Oncol. 2018 Feb;15(2):81-94.

Kalikai et al. Br J Cancer. 2008 Sep 16;99(6):923–929.

Conclusion

• Cytological materials are suitable for molecular analyses

• CSF is an alternative to study EGFR mutation

• Tumor heterogeneity should always be considered (EGFR mutation analyses on various samples)

• Liquid biopsy may reflect genomic aberrations from multiple foci

• When liquid biopsy is negative, tissue should be biopsied to eliminatefalse negative results

Thank you for your attention

June’17 Istanbul