Molecular Subtyping of Endometrial Cancer: A ProMisE ing Change Charles Matthew Quick, M.D. Associate Professor of Pathology Director of Gynecologic Pathology University of Arkansas for Medical Sciences
Disclaimer This talk is slightly esoteric and meant to give a brief introduction to what is probably coming based on the speakers ability to read the future. Only parts of this are ready for clinical use, but he will try his best to make it worth your time!
Outline Background The 4 groups POLE What it means for us
I d like to talk about molecular testing BUT There are benefits to this system! Improved Diagnostics and Treatment Protocols
What is this ProMiseE? Pro = proactive M = Molecular Is = risk classifier (?) E = Endometrial Cancer This came about as a result of TCGA analysis of endometrial cancers back in 2013
Next generation sequencing revealed 4 distinct groups of endometrial cancer Significant differences in progression free survival *Did not include clear cell ca Nature 2013 May 2;497(7447):67-73
TCGA Analysis Somatic copy number alteration (CAN), somatic mutation number and MSI status could classify tumors into 4 types with 4 different outcomes TCGA. Nature 2013
What is NGS looking at? Somatic mutations (single nucleotide variations: SNV) Which gene Type of mutation Pattern of change # of mutations in a given tumor Somatic Copy Number Alterations (CNA) / Copy Number Variations (CNV) Extra copies of a gene, chromosome or chromosomal arm Deletions of DNA material encoding a gene, chromosome or chromosomal arm
The best chart ever made? Nature 2013 May 2;497(7447):67-73
We are not good at classifying endometrial cancers Most are easy, a lot are not No consensus among experts (even with IHC): Guan et al. Int J Gynecol Cancer, 2011 Gilks et al. Am J Surg Pathol, 2013 Han et al. Modern Pathol 2013 Hoang et al. Am J of Surg Pathol, 2013 Because we have a hard time classifying, studying of treatments suffers
Molecular Classification Could Help! Has been shown to be reproducible and associated with outcomes: Salvesen et al. Proc Natl Acad Sci USA, 2009 LeGallo et al. Nat Genet, 2012 McConechy et al. J Pathol, 2012 TCGA. Nature, 2013 More accurate classification = better treatment (eventually)
Back to the ProMisE TCGA. Nature 2013 Talhouk et al. British Journal of Cancer, 2015 & Cancer 2017 Wouldn t it be nice if there was a clinically friendly way to classify the 4 groups identified by the TCGA? This is the aim of ProMisE
Outline Background The 4 groups POLE What it means for us
Copy Number Low (Endometrioid) Most common subset (39%) Relatively low mutational burden (MSS) and low CNAs Frequent PTEN & CTNNB1 mutations Occasional ARID1A (~5%) Rare TP53 Prognosis similar to MSI Nature 2013 May 2;497(7447):67-73
Copy Number Low (Endometrioid) Most endometrioid adenocarcinomas (G1-2 >> G3)
Copy Number High (serous-like) 26% of cases Low overall mutation rate High number of CNAs Very frequent TP53 (>90%) Worst PFS of all groups Nature 2013 May 2;497(7447):67-73
Copy Number High (Serous-Like) Usually Serous Carcinoma, but also some G3 Endometrioids
MSI (Hypermutated) 28% of Cases Some overlap with POLE-mutated group Most CN-L, but can be variable PTEN, KRAS & ARID1A are common Usually somatic (MLH1 methylation), may be germline (Lynch syndrome) Middling prognosis, similar to CNL\Endometrioid Nature 2013 May 2;497(7447):67-73
MSI (Hypermutated) Endometrial Adenocarcinoma Predominantly endometrioid More likely to be high grade (FIGO 3) May be undifferentiated Increased TILs Origin or involvement of the LUS
Outline Background The 4 groups POLE What it means for us
POLE (Ultramutated) Catalytic subunit of DNA polymerase epsilon Proofreads DNA and removes mis-paired nucleotides Tumors have extremely high numbers of mutations Are still copy number alteration low Most are MSS (>90%) Frequent mutations: PTEN, PIK3R1, PIK3CA, KRAS, FBXW7 TP53 mutations in ~35%
POLE (Ultramutated) Accounted for 7% of cases studied by TCGA Thought to compose 5-10% of endometrial cancers Up to 20% of FIGO 3 EMCA Usually FIGO stage 1 LVI is common Excellent prognosis (despite looking horrible) Nature 2013 May 2;497(7447):67-73
POLE (Ultramutated) Histologic features: Usually look high grade but may look low grade Vast majority look (partially) endometrioid Significant number are mixed endometrioid and serous carcinoma Eosinophilic cytoplasm is common Squamous, secretory and mucinous diff may be seen Both TILs and peritumoral lymphocytes common Bottom line: We ve seen these and probably gave up and called them mixed epithelial carcinoma or serous carcinoma Hussein et al. Modern Pathology (2015) 28, 505 514
Array of typical POLE epithelial morphologies
P53 P16
Back to This: Nature 2013 May 2;497(7447):67-73
Outline Background The 4 groups POLE What it means for us Talhouk et al. British Journal of Cancer, 2015 & Cancer 2017
Algorithms Abound ProMisE TransPORTEC POLE EDM? no yes Group 3 (POLE) Talhouk et al. British Journal of Cancer, 2015 & Cancer 2017 MMR IHC defect? yes Group 2 (MSI) no Group 4 (NSMP) no p53 IHC abnl? yes Group 1 (p53) Studied only high risk cancers Stelloo et al. Modern Pathology (2015) 28, 836 844.
TCGA Caveats Limitations : Clear cell carcinoma was not included Other rare histotypes excluded too Often clear cell is in the DDx with other high grade tumors Grade 3 endometrioids are in EACH molecular subtype, both morphologically & molecularly diverse BUT Grade 1 and Serous fit molecular scheme well So a big problem area isn t addressed
Algorithmic Caveats Vast majority of labs cannot sequence POLE Depending on approach some POLE cases will fall in immunohistochemical the MMR-D expression group of p53 (clone DO-7, 1:2,000; Neomarkers) was scored positive if >50% of the tumor Not cells all showed p53 a mutant strong positive staining nuclear staining, cases or when are discrete CN-H geographical patterns showed >50% tumor cell positivity Not all CN-H cases have TP53 mutations Clin Cancer Res; 22(16); 4215 24. 2016 AACR. p53 IHC interpretation is not standard: Null phenotypes can be missed (esp. on small samples) What s positive (>50%, >70%, 90%+)
Most importantly! There is no data on if tumors are best managed and treated according to the histologic vs. molecular classification yet
So what can we do? We can utilize findings to craft IHC panels to help diagnose high grade cancer Nature 2013 May 2;497(7447):67-73
High Grade Carcinoma Panel PTEN: Loss argues against serous (and for endometrioid) p53: Wild-type argues against serous ARID1A: Loss argues against serous MMR-Deficient: Favors endometrioid / undifferentiated p16: Strong, diffuse expression favors serous Pan-Keratin: Expression argues against undifferentiated
Other Stains to Try Napsin A / AMACR: Positive in clear cell carcinoma ER / PR: Negative in most clear cell carcinoma CK 8/18: Rare, strong positive cells in undifferentiated carcinoma
Working up a high grade carcinoma Start with an initial stain panel (PanK, p53, p16, MMR) this varies based in impression Show the case around! Extend IHC panel if needed (ER/PR, Napsin, CK8\18, others)
P53 P16
ER PR MSH6 PTEN FINAL DIAGNOSIS: Endometrioid Adenocarcinoma, FIGO grade 3 Courtesy of Dr. Brooke Howitt Courtesy of Dr. Brooke Howitt
quickcharlesm@uams.edu QUESTIONS?