reprinted from may 2019

pathology ◆ laboratory medicine ◆ laboratory management Response to second-line osimertinib in primary EGFR p.T790M mutation CAP TODAY and the Association for Molecular Pathology have teamed up to bring clinical sensitivity to TKIs is not clear. molecular case reports to CAP TODAY readers. AMP members write the reports using The tumor content of the biopsy tis- clinical cases from their own practices that show molecular testing’s important role in sue in this patient was 30 percent, diagnosis, prognosis, and treatment. The following report comes from Kokilaben Dhi- which is the lower cutoff limit for rubhai Ambani Hospital and Medical Research Institute, Mumbai, India. If you would Sanger sequencing at our center. like to submit a case report, please send an email to the AMP at [email protected]. For more DNA was extracted from the tissue information about the AMP and all previously published case reports, visit www.amp.org. obtained from the core biopsy sample Sewanti Limaye, MBBS, MD, MS; Madhavi Pusalkar, PhD; Foram Kothari, MBBS; Meenal using a QIAamp FFPE kit (Qiagen). Hastak, MBBS, MD; Varsha Vadera, MBBS, MD; Rajesh Mistry, MBBS, MS; Jaya Vyas, PhD Quantified DNA was amplified by Non-small cell lung cancer patients tobacco exposure, presented to our polymerase chain reaction using with epidermal growth factor receptor hospital in November 2016 with a primers specific for exons 18, 19, 20, activating mutations have excellent right neck lump and persistent cough and 21 of EGFR. Obtained PCR prod- response to oral therapy with EGFR of one-month duration. Fine-needle ucts were sequenced by bidirectional tyrosine kinase inhibitors. However, aspiration cytology was suspicious for DNA sequencing on an ABI capillary development of re- squamous cell carci- sequencer.4 Result analysis revealed sistance to first- noma. The patient un- two mutations in the EGFR gene, one and second-gen- derwent staging using in exon 19 (p.L747_T751del) and the eration TKIs is a PET/CT scan, which re- other in exon 20 (p.T790M). well-recognized case report vealed a right upper lobe Discussion. Detection of a com- phenomenon with acquired p.T790M lung mass and right supraclavicular, pound mutation in the EGFR gene is mutation and accounts for most TKI mediastinal, right perihilar, and left a rare occurrence. Nearly one percent drug resistance. Resistance to EGFR para-aortic lymphadenopathy. A core to seven percent of patients have been TKI therapy has been described in biopsy was performed from the right reported to have compound muta- tumors with coexistent primary supraclavicular lymph node and re- tions.5,6 Detection of one sensitive and p.T790M mutation and an EGFR ac- vealed poorly differentiated adenocar- one resistant mutation is an interest- tivating mutation in a small number cinoma of lung primary. ing and complicated situation. Al- of patients. These patients with coex- At the time of the patient’s evalu- though exon 21 and exon 20 muta- istent EGFR activating mutation and ation in 2016, only EGFR mutation tions have been reported as one of the primary p.T790M mutation have been analysis using Sanger sequencing common compound mutations, the reported to have less than adequate and FISH using ALK break-apart combination of exon 19 and exon 20 clinical benefit from first- and second- strategy were being performed as is rare and has been reported in about generation EGFR TKI therapy.1-3 part of routine molecular testing of 0.5 percent of cases in one study.7 We report here a case of advanced lung adenocarcinoma cases. The pa- Clinical response of these rare cases adenocarcinoma of the lung with tient’s tumor specimen was negative to TKI inhibitors is not well studied. primary p.T790M mutation and an for ALK rearrangement by FISH. In light of previous data suggest- EGFR exon 19 deletion that showed Sanger sequencing, the gold-stan- ing a lack of appropriate clinical ben- response to the third-generation dard technique, has the advantage of efit with EGFR TKI therapy in pri- EGFR TKI osimertinib. detecting all the mutations—common mary p.T790M mutation1-3 and the Case. A 54-year-old Indian woman, ones known to be TKI sensitive and large disease burden seen in this otherwise in good health and with no resistant and uncommon ones whose symptomatic patient, a decision was 2 | CAP TODAY

Exon 19: c.2240_2254delTAAGAGAAGCAACAT (p.leu747_Thr751)

Exon 20: c.2369C>T (p.T790M)

made to treat her with standard che- therapy revealed a partial response. osimertinib is known to work both on motherapy doublets and not with The patient experienced significant EGFR exon 19 deletion and second- first- or second-generation EGFR and progressive adverse effects with ary p.T790M mutation8 and was TKIs. The patient received intrave- pemetrexed in the form of a grade launched in India in November 2017. nous pemetrexed 500 mg/m2 and two skin rash, grade two fluid reten- Due to toxicity from maintenance carboplatin 550 mg every three weeks tion, and grade three right subman- pemetrexed and persistent disease, for a total of six cycles, followed by dibular gland inflammation despite our patient with EGFR exon 19 dele- maintenance pemetrexed 500 mg/m2 steroid premedication and anti-aller- tion and primary p.T790M mutation for six additional cycles. A restaging gic administration. was started right away on osimer- PET/CT after three cycles of chemo- The third-generation EGFR TKI tinib 80-mg tablets once daily. She has completed six months of therapy Pretreatment PET/CT with right upper lobe lung mass and right supraclavicular, mediastinal, right without any significant adverse ef- perihilar lymphadenopathy and left para-aortic lymphadenopathy fects and with complete response to therapy on the most recent PET/CT. Even the inflammation in the right submandibular gland has resolved completely. Conclusion. The combination of two genomic aberrations of the EGFR gene—exon 19 deletion and primary p.T790M mutation—was responsive to the third-generation EGFR TKI inhibitor osimertinib, with minimal Post-treatment PET/CT with complete response adverse effects, in this patient with metastatic lung adenocarcinoma. 1. Yu HA, Arcila ME, Hellmann MD, Kris MG, Ladanyi M, Riely GJ. Poor response to erlotinib in patients with tumors containing baseline EGFR T790M mutations found by routine clinical molecular testing. Ann Oncol. 2014;25(2):423–428. 2. Su KY, Chen HY, Li KC, et al. Pretreatment epidermal growth factor receptor (EGFR) T790M mutation predicts shorter EGFR ty- rosine kinase inhibitor response duration in CAP TODAY | 3 patients with non-small-cell lung cancer. J Clin Oncol. 2012;30(4):433–440. 3. Riely GJ, Yu HA, Arcila ME, Hellmann MD, Test yourself Ladanyi M, Kris MG. Response to erlotinib and Here are three questions taken from the prognosis for patients with de novo epidermal case report. Answers are online now at growth factor receptor (EGFR) T790M muta- www.amp.org/casereports and will be pub- tions. J Clin Oncol. 2013;31(15)(suppl):8018. lished next month in CAP TODAY. 4. Pao W, Miller V, Zakowski M, et al. EGF receptor gene mutations are common in lung 1. The p.T790M mutation in EGFR is cancers from “never smokers” and are as- clinically significant because: sociated with sensitivity of tumors to gefi- a. Its detection means increased sensitivity to tinib and erlotinib. Proc Natl Acad Sci USA. tyrosine kinase inhibitors. 2004;101(36):13306–13311. b. It arises as a secondary resistance mutation in response to first-generation tyrosine kinase 5. Hata A, Yoshioka H, Fujita S, et al. Complex inhibitors. mutations in the epidermal growth factor c. Patients with this mutation respond well to receptor gene in non-small cell lung cancer. J osimertinib. Thorac Oncol. 2010;5(10):1524–1528. 6. Zhang B, Xu J, Zhang X, et al. Coexistence of 2. Presence of a compound mutation sensitive and resistant epidermal growth factor in the EGFR gene: receptor (EGFR) mutations in pretreatment a. means there are two or more different het- non-small cell lung cancer (NSCLC) patients: erozygous mutations present in the same first or third generation tyrosine kinase inhibi- gene. tors (TKIs)? Lung Cancer. 2018;117:27–31. b. complicates and alters the patient’s response 7. Peng M, Weng YM, Liu HL, et al. Clinical to targeted therapy. characteristics and survival outcomes for non- c. means real-time PCR will be a good technique small-cell lung cancer patients with epidermal for detection. growth factor receptor double mutations. 3. Which technique is ideal to detect all Biomed Res Int. 2018;2018:7181368. possible EGFR mutations present in a 8. Mok TS, Wu Y-L, Ahn M-J, et al. Osimertinib patient’s sample? or platinum-pemetrexed in EGFR T790M- a. Sanger sequencing. positive lung cancer. N Engl J Med. 2017; b. Real-time PCR—it is a sensitive technique 376(7):629–640. and can detect mutations in samples with low tumor content. Drs. Limaye, Pusalkar, Kothari, Hastak, c. Next-generation sequencing—it is a sensitive tool to detect rare and common EGFR Vadera, Mistry, and Vyas are with Kokila- mutations. ben Dhirubhai Ambani Hospital and Med- ical Research Institute, Mumbai, India.