In:
Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 39, No. 15_suppl ( 2021-05-20), p. 4526-4526
Abstract:
4526 Background: LNEC is a rare, poorly characterized entity morphologically resembling small cell NEC of the urothelial tract (SNEC). Methods: Pure and partial LNEC and SNEC cases were identified by histopathologic re-review; clinical outcomes were compared. A subset was sequenced with MSK-IMPACT (279-505 genes). Results: Between 1992-2020, 43 patients (pts) with LNEC were identified (42 bladder, 1 upper tract); 19 (44%) had concomitant SNEC. LNEC cases were compared to 192 SNEC without LNEC (SNEC-only) (Table 1). Compared to SNEC-only pts, LNEC pts experienced longer overall survival (OS), adjusting for age and M0 vs M1 (median OS not reached vs 22.4 months [mos]; HR 0.34, 95% CI 0.16-0.74, p =.006). Neoadjuvant chemo (NAC) use increased over time. Pathologic response rate ( 〈 ypT2N0) after NAC was 25% for LNEC and 50% for SNEC-only (p =.13); the ypT0N0 rate was 25% for LNEC and 40% for SNEC-only (p =.52). Perioperative chemo did not improve OS compared to surgery alone in LNEC, adjusting for age and concurrent SNEC (HR 1.46, 95% CI 0.12-17.5, p =.76), but was associated with longer OS among SNEC-only pts (n = 98; HR 0.39, 95% CI 0.22-0.69, p =.001). Two M1 LNEC pts received immunotherapy (IO) in the first-line: 1 atezolizumab, 1 atezolizumab + chemo. Both remained free of progression on IO at a follow-up of 20 and 12 mos, respectively. Of 18 sequenced LNEC tumors, 89% had TERT promoter alterations (alts), similar to 85% seen in 52 SNEC tumors. All LNEC tumors had alts of TP53 or RB1, and 10 (56%) had both. Median tumor mutational burden (TMB) was 14 (IQR 8-38) in LNEC and 30 (IQR 15-55) in SNEC. Epigenetic modifiers were altered in 78% LNEC and 79% SNEC. Two LNEC pts had ERCC2 alts and received platinum chemo; both were alive at last follow-up from NEC diagnosis of 30.7-39.1 mos. Conclusions: LNEC pts experienced longer OS compared to pts with SNEC-only in this cohort, but did not appear more chemo-sensitive. Genomic profiles of LNEC and SNEC-only tumors were similar; TERT promoter mutations suggest a potential urothelial precursor. Further investigation of IO for LNEC is warranted.[Table: see text]
Type of Medium:
Online Resource
ISSN:
0732-183X
,
1527-7755
DOI:
10.1200/JCO.2021.39.15_suppl.4526
Language:
English
Publisher:
American Society of Clinical Oncology (ASCO)
Publication Date:
2021
detail.hit.zdb_id:
2005181-5
