Greipp, Patricia T.

e19078 Background: MECOM (EVI1) rearrangements in MDS/AML are rare and carry an unfavorable prognosis. Although allogeneic stem cell transplantation (allo-HSCT) may prolong survival, factors impacting outcomes are not known. We conducted a retrospective analysis of patients with MECOM (EVI1) to associate clinicopathologic variables with prognosis. Methods: This study was approved by the Mayo Clinic IRB. Patients >18 years of age with MDS or AML and MECOM EVI1 at Mayo Clinic between 01/2012 and 12/2022 were included. Response was defined by ELN criteria. Intensive chemotherapy was defined as 7+3 or high dose cytarabine. Non-intensive chemotherapy included hypomethylating agents with or without venetoclax. Median overall survival (OS) and median leukemia free survival (LFS) were estimated using the Kaplan-Meier method. Outcome differences between sub-groups and univariate analyses were assessed with Cox regression. Results: Sixty patients met criteria for inclusion. Sixty-three percent (n = 38) were male and the median age at diagnosis was 67.8 yrs (range, 56 – 75). Eighty percent had AML (n = 48) and 18% had MDS (n = 11). Sixty-seven percent of patients had secondary AML/MDS (n = 40). Inv(3)/t(3;3) was present in 65% (n = 39) and t(3;21) was present in 12% (n = 7). Thirty-eight percent (n = 23) of patients had cooccurring monosomy 7 or 7q deletion and 5% had complex karyotype (n = 3). SF3B1 was the most common cooccurring mutation in 31% (n = 10), followed by KRAS in 19% (n = 6). Thirty-eight percent of patients (n = 23) received intensive chemotherapy. Complete response (CR) rates were 36% with intensive treatment (n = 8) and 4% with non-intensive treatment (n = 1; p = 0.007). Thirty percent (n = 18) underwent SCT (78% in CR1 and 22% in CR2) and of those, myeloablative conditioning (MAC) was used in 38% while 61% received reduced intensity conditioning (RIC). The mOS in the entire cohort was 11 months (95% CI 6.2, 17). Patients who received a SCT had longer mOS compared to patients who did not (19 vs 6.2 months, HR = 0.31, 95% CI 0.16,0.64; p = 0.001). AML-MRC was a poor prognostic factor in the HCST group for OS (HR = 4.23, 95% CI 1.02, 17.5, p = 0.047). Intensive vs. non-intensive chemotherapy, response prior to transplant (CR vs. no CR), or having 2 or more mutations on NGS did not significantly impact OS or LFS. Conclusions: In line with previous reports, allo-HSCT was associated with improved survival outcomes. Our results showed a high frequency of secondary AML/MDS, but only AML-MRC was associated with decreased survival outcomes. Regardless of therapy type, outcomes were poor. Novel therapies are urgently needed for these patients.

AbstractETV6 mutations are rare but recurrent somatic events in myeloid neoplasms and are negatively prognostic in myelodysplastic syndrome. We set out to examine the clinical and molecular characteristics of patients undergoing investigation for myeloid neoplasms, found to have deleterious ETV6 mutations. ETV6 mutations occurred in 33 of 5793 (0.6%) cases investigated and predominantly in high‐risk disease entities including MDS with increased blasts, primary myelofibrosis and AML, myelodysplasia‐related. In three cases, isolated iso (17q) karyotype was concurrently detected, an otherwise rare karyotype in myeloid neoplasms. ETV6 mutations were frequently subclonal and never occurred as an isolated abnormality with ASXL1 (n = 22, 75%), SRSF2 (n = 14, 42%) and SETBP1 (n = 11, 33%) the predominant co‐mutations. Restricting to patients with MDS, higher rates of ASXL1, SETBP1, RUNX1 and U2AF1 mutations occurred in ETV6 mutated cases, relative to a consecutive control cohort with wild‐type ETV6. The median OS of the cohort was 17.5 months. This report highlights the clinical and molecular associations of somatic ETV6 mutations in myeloid neoplasms, suggests their occurrence as a later event, and proposes further translational research questions for their role in myeloid neoplasia.

Abstract Multiple myeloma (MM) develops from well-defined precursor stages; however, invasive bone marrow (BM) biopsy limits screening and monitoring strategies for patients. We enumerated circulating tumor cells (CTC) from 261 patients (84 monoclonal gammopathy of undetermined significance, 155 smoldering multiple myeloma, and 22 MM), with neoplastic cells detected in 84%. We developed a novel approach, MinimuMM-seq, which enables the detection of translocations and copy-number abnormalities through whole-genome sequencing of highly pure CTCs. Application to CTCs in a cohort of 51 patients, 24 with paired BM, was able to detect 100% of clinically reported BM biopsy events and could replace molecular cytogenetics for diagnostic yield and risk classification. Longitudinal sampling of CTCs in 8 patients revealed major clones could be tracked in the blood, with clonal evolution and shifting dynamics of subclones over time. Our findings provide proof of concept that CTC detection and genomic profiling could be used clinically for monitoring and managing disease in MM. Significance: In this study, we established an approach enabling the enumeration and sequencing of CTCs to replace standard molecular cytogenetics. CTCs harbored the same pathognomonic MM abnormalities as BM plasma cells. Longitudinal sampling of serial CTCs was able to track clonal dynamics over time and detect the emergence of high-risk genetic subclones. This article is highlighted in the In This Issue feature, p. 247

Abstract Overall Survival estimates from diagnosis are valuable for guiding treatment, but do not consider the years already survived. Conditional survival (CS) provides dynamic survival predictions over time. This study was conducted to estimate CS at 1–8 years from diagnosis and the impact of baseline prognostic factors on CS in multiple myeloma (MM) patients. This is a retrospective study including 2556 MM patients diagnosed between 2004–2019. CS (t|s) was defined as the probability of surviving t years given survival of s years. Median age was 64 years. Median follow-up was 6.2 years and median overall survival from diagnosis was 7.5 years. The 5-year CS estimates at s = 0, 1, 2, 3, and 5 years were 0.64, 0.61, 0.61, 0.61, and 0.58, respectively. On multivariate analysis, age ≥ 65 and proteasome inhibitor + immunomodulatory-based induction were associated with decreased survival and increased survival, respectively, retained at 5 years. The adverse impact of 1q gain/amplification, high-risk IgH translocation, and ISS-3 was significant at 1 and 3 years but not 5 years. Chromosome 17 abnormality was associated with decreased survival only at 1 year. Among MM patients, 5-year CS was stable at 1–5 years from diagnosis. The prognostic impact of high-risk cytogenetic factors decreased with additional years survived.

Cholangiocarcinoma (CCA) is a highly lethal cancer arising from the biliary tract epithelium. The cancer biology of this neoplasm is not well understood. To date, only a few CCA cell lines have been reported, which were mostly developed from Asian patients. In this study, we report and characterize a new intrahepatic CCA cell line, LIV27, derived from a surgically resected tumor in a 67-year-old Caucasian woman with primary sclerosing cholangitis (PSC). LIV27 cells grow well in collagen-coated flasks or plates with a doubling time of 57.8 h at passage 14. LIV27 cells have high tumorigenicity in nude mice and stain positive for CK7 and CK19, markers that differentiate CCA from hepatocellular carcinoma. Karyotype analysis showed that LIV27 is aneuploid. We established a single-locus short tandem repeat profile for the LIV27 cell line. This newly established cell line will be a useful model for studying the molecular pathogenesis of, and developing novel therapies for, cholangiocarcinoma.