Huang, Ying

Introduction: Complex karyotype (CK, ≥3 chromosome (chr) abnormalities (abn)) is an important adverse prognostic indicator in chronic lymphocytic leukemia (CLL). CK at diagnosis (dx) of CLL, particularly with major structural chr abn (i.e. unbalanced translocation, add, marker, ring chr), called type-2 CK (CK2), has been associated with an increased risk of Richter transformation (RT) (Visentin Haematologica 2022). RT is defined as development of aggressive lymphoma, most often large B-cell lymphoma, in the setting of CLL. In patients (pts) with relapsed/refractory CLL treated with ibrutinib, CK as a continuous variable and the presence of polyploidy were independent predictors for RT. CK is a common finding at the time of RT, and high-CK (≥5) has been associated with short survival in RT, although previous studies predominantly included pts with prior chemoimmunotherapy (CIT) administration for their CLL. The prognostic significance of CK in pts with RT whose prior CLL-directed therapies include only non-CIT, as is the current standard of care for CLL, has not been evaluated. Methods: We conducted a multicenter, retrospective analysis of pts from 14 academic centers. Pts with RT diagnosed between 6/2011 to 6/2023, who had CLL-directed treatment that did not include prior CIT, with stimulated karyotype data available, were included. Pts who did not receive treatment for their CLL prior to developing RT were not included. Baseline pt, disease, and cytogenetics data were collected via chart review at time of CLL diagnosis and at the development of RT. Karyotype abn up to 20 were counted on both CLL tissue (peripheral blood or bone marrow) and RT tissue using IWGMC guidelines (Chun Leuk Res 2010). CK was categorized as CK1 (balanced abn, deletion, aneusomies) or CK2. Polyploidy was defined as ≥58 chrs. Karyotype was considered evolved if one or more chr abn were seen in a follow-up sample of CLL tissue that were not seen at CLL dx.TP53 disruption was defined as presence of del(17p) or TP53 mutation. Overall survival (OS) was measured from RT dx and estimated using the Kaplan-Meier method. Cox regression model was used to identify prognostic factors associated with OS. Results: A total of 64 eligible pts were identified. Median age at RT dx was 65 years (range 40-89) and 71.9% of pts were male. Of those evaluated (n=49), 79.6% had unmutated IGVH. Median number of therapies for CLL prior to RT was 1 (range 1-5) and included BTK inhibitor (n=37), BCL2 inhibitor (n=3), both (n=18), or other non-CIT treatment (n=6). At CLL diagnosis, 54.7% of pts had a CK, and the median number of chr abn was 3 (range 0-20). Of those with CK, 96.9% had a CK2, and 6.3% had a polyploid subclone. TP53 disruption was found in 46% of pts. At time of RT, chr analysis of CLL tissue was available for 38 pts and showed 78.9% had a CK, and the median number of chr abn was 8 (range 0-20). Polyploidy was found in 29.6%. TP53 disruption (46 pts evaluated) was found in 52.2%. Karyotype evolution from dx (35 pts evaluated) occurred in 74.3% of pts. In RT tissue, of those evaluated (n=29), 96.6% were clonally related to the preceding CLL. MYC translocation (45 pts evaluated) occurred in 17.8%. CK (20 pts evaluated) was found in 70%, with a median number of chr abn of 8 (range 0-20). Of those with CK, 33.3% had a polyploid subclone. With a median follow-up of 17.8 months (range 2.1-83.0) there were 42 deaths, with a median OS of 14.3 months (range 6.9-29.1). For this subset of patients with karyotype data available who would go on to develop RT, an exploratory univariable analysis for OS from RT found that increasing number of chr abn as a continuous variable at CLL dx was associated with worse OS (HR 1.10, 95% CI 1.02-1.19, p=0.01). Similarly, at RT, increasing number of chr abn in CLL tissue (HR 1.09, 95% CI 1.02-1.16, p=0.01) and in RT tissue (HR 1.09, 95% CI 1.01-1.18, p=0.03) was also prognostic of survival. Karyotype evolution in CLL tissue at RT (HR 3.02, 95% CI 1.02-8.94, p=0.05) was borderline significant for worse OS. Conclusions: Our multi-center study identified increasing number of chr abn at CLL diagnosis and at time of RT, and clonal evolution in the CLL tissue, are associated with worse OS in pts with RT whose CLL was treated without CIT. Limitations include incomplete cytogenetics data across the cohort and potential variability across institutions in cytogenetics laboratory practices. This provides further evidence for the clinical utility of chr analysis in the modern era of CLL therapy.

Introduction: Richter transformation is the development of an aggressive lymphoma, most commonly diffuse large B-cell lymphoma, in patients (pts) with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Transformation into Hodgkin lymphoma (HT) is a rare event and outcomes in pts with this complication in the current CLL/SLL therapeutic era of small molecule inhibitors (SMI; e.g., Bruton tyrosine kinase inhibitors [BTKi] and BCL2 inhibitors [BCL2i]) are unknown. Methods: We conducted a retrospective study of pts from 12 academic centers. Pts with HT who had not previously received chemotherapy for CLL/SLL-directed treatment (tx) were included. Pt, disease, and tx characteristics were collected. HT was categorized into 3 groups: “Concurrent HT,” defined as HT and CLL/SLL diagnosed simultaneously (within 3 months); “HT without prior CLL/SLL tx,” defined as HT and CLL/SLL diagnosed >3 months apart with the CLL/SLL never treated; and “HT with prior non-chemotherapy tx for CLL/SLL” defined as having received non-chemotherapy CLL/SLL-directed tx prior to the diagnosis (dx) of HT. Overall survival (OS) was measured from HT dx and estimated using the Kaplan-Meier method. Cox regression model was used to identify prognostic factors associated with OS. Results: Within a total cohort of 402 pts with Richter transformation (all histologies) without prior chemotherapy, 41 pts with HT (10%) were identified: 12 with concurrent HT, 10 with HT without prior CLL/SLL tx, and 19 with HT with prior non-chemotherapy tx for CLL/SLL. The median age at CLL/SLL dx was 62 years (range 31-96 years) and 73% were male. At CLL/SLL dx, 67% (14/21 evaluated) had unmutated IGHV, and 24% (8/34 evaluated) had TP53 disruption (del(17p) and/or TP53 mutation). The median age at HT dx was 65 years (range 31-96 years) among all pts. At HT dx, there was no significant difference in highest SUV on PET (median 12.3, range 3-31.1), lactate dehydrogenase (LDH) level (median 242 U/L, range 112-859 U/L), or lymph node longest diameter (median 4.6 cm, range 1.6-25 cm) among the 3 subgroups. The median time from CLL/SLL dx to HT dx was 5.4 years (range 0.3-16.5 years) in pts with HT without prior CLL/SLL tx and 4.2 years (range 0.5-17.3 years) in pts with HT with prior non-chemotherapy tx for CLL/SLL. The median number of prior non-chemotherapy CLL/SLL-directed tx was 1 (range 1-6) and included BTKi only (n=17) and BTKi and BCL2i sequentially (n=2); no patient had received only prior BCL2i. Among the 19 pts with HT with prior non-chemotherapy tx for CLL/SLL, 18 pts were on active tx at time of dx (17 BTKi, 1 BCL2i). Initial HT management included: doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD; n=16), brentuximab vedotin (BV)-AVD (n=10), radiation only (n=2), other systemic tx (n=11), and supportive cares / hospice (n=2). All but 1 of the 11 other systemic tx were various HL tx regimens. Across all pts with available data (n=32), the overall response rate to 1st line HT tx was 78% (69% complete response rate); 13% had progressive disease and 9% (n=3; all with concurrent HT) died within 6 months without formal response assessment. A total of 11 pts received at least 1 additional line of therapy for HT, which included BV (n=4), an immune checkpoint inhibitor (n=1), or both (n=6) at any point beyond 1st line HT tx. Median follow-up from HT dx was 32.8 months (range 2.4-253.8 months). The 36-month OS for the entire cohort was 75% (95% CI: 55-87%). The 36-month OS estimates by subgroups were: 62% (95% CI: 26-84%) in pts with concurrent HT, 100% in pts with HT without prior CLL/SLL tx (no events by 36 months), and 67% (95% CI: 33-87%) in pts with HT with prior non-chemotherapy tx for CLL/SLL. Exploratory univariable analysis identified TP53 disruption at CLL dx (HR 12.36; 95% CI: 2.55-59.84) and lymph node longest diameter (HR 1.32 per 1 cm increase; 95% CI: 1.12-1.55) and LDH 2-fold increase (HR 3.97; 95% CI 1.24-12.68) at HT dx as prognostic for worse OS. HT subgroup was not prognostic. Conclusions: This is the largest report of outcomes in pts with CLL/SLL who develop HT following SMI tx without any prior chemotherapy, representing a contemporary cohort. Prior CLL/SLL tx status was not associated with OS; however, cautious interpretation is required given the sample size. Our findings support the use of appropriate HL-directed treatment in the setting of HT; however, OS estimates remain worse than would be expected in an older adult de novo HL cohort (Cheng Blood Adv 2022).

Abstract There are limited data assessing the risk scores for primary treatment failure (PTF) in patients with classical Hodgkin lymphoma (cHL; PTF-cHL) undergoing autologous hematopoietic cell transplantation (auto-HCT). ECLIPSE (Evaluation of Classical Hodgkin Lymphoma patients wIth Primary treatment failure and analySis of outcomEs) is a multicenter retrospective cohort of patients with PTF-cHL (aged ≥15 years) diagnosed on or after 1 January 2005, at 15 US medical centers. PTF was defined as 1 of the following patterns of failure: (1) progressive disease by imaging during or within 6 weeks of completion of frontline chemotherapy (primary progression [PP]); (2) partial response (PR) or stable disease (SD) by imaging after completion of frontline treatment (PR/SD); (3) progression of disease by imaging (and confirmed by biopsy) within 12 months of frontline therapy completion after prior documentation of complete response (CR; early relapse [ER]). A total of 478 patients were included in the analysis. Among these, 217 (45%) were PP, 86 (18%) were PR/SD, and 175 (37%) were ER. The 6-month and 1-year cumulative incidence of nonrelapse mortality after auto-HCT were 0.9% and 1.1%, respectively. The median progression-free survival (PFS) and overall survival (OS) after auto-HCT were 4.33 and 10.09 years, respectively. Although those not in CR at the time of auto-HCT were associated with inferior PFS and OS, advanced age and diagnosis before 2011 were associated with inferior OS. This study showcases the safety and long-term efficacy of auto-HCT, even in patients with high-risk disease who are traditionally considered chemotherapy refractory, and will serve as a benchmark for the ongoing transplant vs no transplant trials.

Abstract Although the 2022 European LeukemiaNet (ELN) acute myeloid leukemia (AML) risk classification reliably predicts outcomes in younger patients treated with intensive chemotherapy, it is unclear whether it applies to adults ≥60 years treated with lower-intensity treatment (LIT). We aimed to test the prognostic impact of ELN risk in patients with newly diagnosed (ND) AML aged ≥60 years given LIT and to further refine risk stratification for these patients. A total of 595 patients were included: 11% had favorable-, 11% intermediate-, and 78% had adverse-risk AML. ELN risk was prognostic for overall survival (OS) (P < .001) but did not stratify favorable- from intermediate-risk (P = .71). Within adverse-risk AML, the impact of additional molecular abnormalities was further evaluated. Multivariable analysis was performed on a training set (n = 316) and identified IDH2 mutation as an independent favorable prognostic factor, and KRAS, MLL2, and TP53 mutations as unfavorable (P < .05). A “mutation score” was calculated for each combination of these mutations, assigning adverse-risk patients to 2 risk groups: −1 to 0 points (“Beat-AML intermediate”) vs 1+ points (“Beat-AML adverse”). In the final refined risk classification, ELN favorable- and intermediate-risk were combined into a newly defined “Beat-AML favorable-risk” group, in addition to mutation scoring within the ELN adverse-risk group. This approach redefines risk for older patients with ND AML and proposes refined Beat-AML risk groups with improved discrimination for OS (2-year OS, 48% vs 33% vs 11%, respectively; P < .001), providing patients and providers additional information for treatment decision-making.

Background: Richter Transformation (RT) refers to the development of an aggressive lymphoma in the setting of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Small molecule inhibitors (SMI), such as the Bruton tyrosine kinase inhibitors (BTKi) and BCL2 inhibitors (BCL2i), have revolutionized the treatment of CLL/SLL. Prior studies evaluated outcomes of patients (pts) with RT in an era where chemoimmunotherapy (CIT) was typically used to treat CLL/SLL. Now that SMI are standard of care, fewer pts with CLL/SLL receive CIT, therefore we sought to determine which variables predict survival in pts who developed RT without prior CIT exposure for CLL/SLL. Methods: We conducted an international multicenter retrospective study of pts from 11 academic centers. Pts with RT occurring as large B-cell lymphoma who did not previously receive CIT (e.g., fludarabine, cyclophosphamide, bendamustine, chlorambucil) for their CLL/SLL were included. We collected pt, disease, and treatment (tx) characteristics. RT was categorized into 3 groups: “Concurrent RT,” defined as RT and CLL/SLL diagnosed simultaneously (within 3 months [mos]); “RT w/o prior CLL/SLL tx,” defined as RT and CLL/SLL diagnosed >3 mos apart with the CLL/SLL never treated; and “RT with prior non-CIT tx for CLL/SLL” defined as having received prior CLL/SLL tx. Overall survival (OS) was measured from RT diagnosis (Dx) and estimated using the Kaplan-Meier method. Cox regression model was used to identify prognostic factors associated with OS. Results: 242 pts were identified. At CLL/SLL Dx, 66% of pts had unmutated IGHV, 37% had del17p/ TP53 disruption, and 20% had trisomy 12. At RT Dx, 56% of the RT with prior non-CIT tx for CLL/SLL group had a del17p/ TP53 disruption versus 27% for the concurrent RT group and 18% for the RT w/o prior CLL/SLL tx groups. Median time from CLL/SLL Dx to RT Dx was 47 mos (range 3-394) for RT w/o prior CLL/SLL tx and 46 mos (range 4-218) for RT with prior non-CIT tx for CLL/SLL. Pts with prior non-CIT tx for CLL/SLL received a median of 1 (range 1-5) prior tx. 86% of pts previously received a BTKi or a BCL2i for tx of CLL/SLL (54% BTKi only, 5% BCL2i only, 27% both). The remaining 14% had been treated with an anti-CD20 monoclonal antibody (MoAb), steroids, lenalidomide, radiation, or alemtuzumab. 85% of pts developed RT while on active tx with SMI. Median age at RT Dx was 69 years (range 37-92). At RT Dx, 38% and 21% of pts had del17p/ TP53 disruption, and trisomy 12 in CLL/SLL tissue, respectively. At RT Dx, there was no difference in highest SUV on PET (median 16, range 2.9-65.6), LDH (median 325, range 103-8162, ULN range 180-271), largest lymph node in diameter (median 4.9 cm, range 0-17.1), Ki-67 (median 80%, range 5%-100%), rate of GCB subtype (27%), presence of MYC translocation (20%), or CLL/SLL and RT clonal relationship (81%) for those pts tested amongst the 3 groups ( Table). The most common 1 st line tx for RT was CIT with or w/o radiation and/or steroids (76%), followed by CIT plus SMI (13%), SMI single agent or combination (7%), and other (4%, which includes anti-CD20 MoAb). Median follow-up from RT Dx was 42.3 mos; the median OS for the entire cohort was 25.8 mos (95% CI: 16.8-49.1). Pts with RT after non-CIT tx for CLL/SLL had a significantly worse OS (median 8.2 mos [95% CI: 5.6-14.3]) than pts with concurrent RT (median 46.3 mos [95% CI: 23.8-96.9]) and RT w/o prior CLL/SLL tx (median 63.5 mos [95% CI: 28.3-70.3]) ( Figure). From an exploratory univariable analysis, we found RT after non-CIT tx for CLL/SLL compared to concurrent RT (HR 2.32 [95% CI: 1.55-3.46]), RT Dx age (HR for 5-year increase 1.14 [95% CI: 1.05-1.23]), del17p/ TP53 disruption (HR 2.27 [95% CI: 1.45-3.56]), and LDH (HR for 2-fold increase 1.37 [95% CI: 1.20-1.58]) were prognostic for worse OS. Conclusions: This is the largest cohort of pts who developed RT having received only SMI with no CIT for their CLL reported, thus reflecting the current treatment landscape. Despite being CIT-naïve, pts in our series who received tx for their CLL/SLL and then developed RT had a short OS, underscoring the need to develop better therapies for these pts. In contrast, as in other published analyses (Wang Haematologica 2020), pts w/o prior tx for CLL/SLL had more favorable outcomes, with a median OS of approximately 5 years. Further analysis to determine PFS and OS by tx for RT for pts who have been treated with SMI for their CLL/SLL is ongoing.

Abstract Enasidenib (ENA) is an inhibitor of isocitrate dehydrogenase 2 (IDH2) approved for the treatment of patients with IDH2-mutant relapsed/refractory acute myeloid leukemia (AML). In this phase 2/1b Beat AML substudy, we applied a risk-adapted approach to assess the efficacy of ENA monotherapy for patients aged ≥60 years with newly diagnosed IDH2-mutant AML in whom genomic profiling demonstrated that mutant IDH2 was in the dominant leukemic clone. Patients for whom ENA monotherapy did not induce a complete remission (CR) or CR with incomplete blood count recovery (CRi) enrolled in a phase 1b cohort with the addition of azacitidine. The phase 2 portion assessing the overall response to ENA alone demonstrated efficacy, with a composite complete response (cCR) rate (CR/CRi) of 46% in 60 evaluable patients. Seventeen patients subsequently transitioned to phase 1b combination therapy, with a cCR rate of 41% and 1 dose-limiting toxicity. Correlative studies highlight mechanisms of clonal elimination with differentiation therapy as well as therapeutic resistance. This study demonstrates both efficacy of ENA monotherapy in the upfront setting and feasibility and applicability of a risk-adapted approach to the upfront treatment of IDH2-mutant AML. This trial is registered at www.clinicaltrials.gov as #NCT03013998.

Abstract Background: GILT is an oral potent selective FLT3 kinase inhibitor approved for marketing for the treatment (Tx) of patients (pts) with relapsed/refractory FLT3 mutated (FLT3m) AML but efficacy in older ND FLT3m AML pts is unknown. Furthermore, FLT3m can be present as a dominant or subclone and impact of FLT3 inhibitor therapy in this setting is uncertain. Here we report the results of a Phase 2/1b sub-study of the Beat AML Master Trial to assess the efficacy of GILT monotherapy (GILTm) in ND FLT3m AML pts aged ≥60 years with high and low VAF and the subsequent response-driven addition of DEC Tx. (ClinicalTrials.gov NCT03013998) Methods: The study was an open-label multicenter (15 sites), 3-outcome, 2-stage Phase 2 design that assigned pts to either Dominant FLT3/Group 1 (GP1) or Non-Dominant FLT3/Group 2 (GP2) as shown in Figure 1. Key eligibility criteria included ND FLT3m AML pts with high and low VAF and/or ITD ratio, aged ≥60 years, and ECOG performance status 0-2. In the Phase 2 study, all pts received GILTm 120 mg/day on days 1 - 28. Pts without CR/CRi after cycle 2 were transferred to the Phase 1b study to receive GILT + DEC (Figure 1). Phase 1b study utilized a standard 3+3 design to evaluate the safety/tolerability of concurrent GILT + DEC. Pts received GILT (dose level 1 [DL1] = 80 mg/day or dose level 2 [DL2] = 120 mg/day on days 1-28) + DEC 20 mg/m 2 IV on days 1-10 or 1-5 every 28 days. Primary endpoint was CR+CRi rate (Phase 2). Response was assessed using modified 2017 ELN AML criteria. The non-dominant GP2 was stopped for futility, GP1 was stopped early to modify trial to include venetoclax. Results: Phase 2 - Between 9/10/2018 to 2/11/2020, 19 / 20 enrolled pts (GP1: n = 9; GP2: n = 10) received GILTm and were included in analyses. Baseline pt characteristics are shown in Table 1. Median (range) time on GILTm was 3 cycles (1 - 18) in GP1 and 1 cycle (1 - 9) in GP2. Most common reasons for discontinuing Tx were Tx failure (TF; 44%) and relapse (33%) in GP1 and TF (70%) and disease progression (PD; 20%) in GP2. Overall CR+CRi was achieved in 4 pts (44%) in GP1 and 1 pt (10%) in GP2. Response duration are shown in Table 2. After median follow-up of 14.3 months (mos) and 19 mos in GP1 and GP2, respectively, 1-year OS was 56% and 76%. Most common Grade ≥3 adverse events (AEs) were febrile neutropenia and colitis (each 25%) in GP1; anemia and low platelet count in GP2 (each 30%). Overall, 7 pts had 15 serious AEs (SAEs) and all SAEs occurred in GP1 pts; most common SAE was colitis (25%) and 1 pt (13%) had a Tx-related Grade 3 SAE of tumor lysis syndrome. In GP2, 1 pt (10%) had Tx-related Grade 2 AE of differentiation syndrome. In GP1, 2 pts died within 60 days of Tx and none in GP2. Phase1b - After up to 2 cycles of GILTm, 12 pts with no CR/CRi (GP1: n = 4; GP2: n = 8) were transferred to receive GILT + DEC (Figure 1). At the time of this report, 1 pt with CRh remained on Tx. Median total time on Tx (including GILTm) was 4 cycles and median time on GILT + DEC Tx was 3 cycles (Table 2). Most common reasons for discontinuing Tx were PD (33%) and TF (25%); and 2 pts (17%) stopped Tx due to an AE. Pts were treated with DL1 GILT + DEC (n = 3), then DL2 GILT + DEC (n = 9); only 1 pt had dose-limiting toxicity (DLT) at DL2 (Grade 3 hyperbilirubinemia and pneumonitis requiring steroid therapy), hence, DL2 GILT + DEC was considered the MTD. CR+CRi rate was 25% in 3 pts, all at DL2 (Table 2). After a median follow-up of 17.8 mos, the 1-year OS from start of GILT + DEC Tx was 57%. Most common Grade ≥3 Tx-related AEs were anemia, febrile neutropenia and low WBC count (each 22%). Overall, 6 pts had 12 SAEs; 1 pt with SAE of Grade 4 sepsis died. Three GILT-related SAEs occurred in 1 pt - Grade 3 hyperbilirubinemia, and pneumonitis and Grade 1 transaminases increased. One pt died within 30 days and a second within 60 days of Tx. No difference was observed in GILT pharmacokinetics (PK) with or without DEC, however steady state Ctrough values were 1.4 to 2.3-fold greater than in relapsed/refractory AML pts (Admiral trial). Conclusions: In ND pts ≥60 years old with dominant FLT3 AML, GILTm induced a high 44% CR+CRi rate and long median OS (21.7 mos). Pts with non-dominant FLT3 had low 10% CR+CRi rate. GILTm was generally safe and was associated with differentiation syndrome in 1 pt. Concurrent GILT + DEC was acceptably tolerated, only 1 pt had a DLT, and the MTD was 120 mg/day GILT + DEC. A subset of pts with no CR/CRi during GILTm achieved remission with addition of DEC. Based on these results, a triple combination Tx study with venetoclax is currently enrolling. Figure 1 Figure 1. Disclosures Traer: Genentech: Membership on an entity's Board of Directors or advisory committees; Schrodinger: Research Funding; Incyte: Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Servier/Agios: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; ImmunoGen: Membership on an entity's Board of Directors or advisory committees. Mims: Glycomemetics: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Aptevo: Research Funding; Leukemia and Lymphoma Society's Beat AML clinical study: Consultancy, Research Funding; Genentech: Consultancy; Xencor: Research Funding; Kartos Pharmaceuticals: Research Funding; Abbvie: Consultancy; BMS: Consultancy; Kura Oncology: Consultancy; Syndax Pharmaceuticals: Consultancy; BMS: Consultancy; Jazz Pharmaceuticals: Consultancy; Aptevo: Research Funding. Stein: Agios Pharmaceuticals, Inc: Consultancy; Novartis: Consultancy; Astellas: Consultancy; Syndax Pharmaceuticals: Consultancy; Daiichi Sankyo: Consultancy; Syros Pharmaceuticals, Inc.: Consultancy; PinotBio: Consultancy; Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Jazz Pharmaceuticals: Consultancy; Foghorn Therapeutics: Consultancy; Blueprint Medicines: Consultancy; Gilead Sciences, Inc.: Consultancy; Abbvie: Consultancy; Janssen Pharmaceuticals: Consultancy; Genentech: Consultancy. Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Kovacsovics: AbbVie: Research Funding; Jazz Pharmaceutials: Honoraria; Janssen Pharmaceuticals: Research Funding; Amgen Inc.: Research Funding; Stemline: Honoraria; Novartis: Research Funding. Blum: Xencor: Research Funding; Abbvie: Honoraria; Nkarta: Research Funding; Celyad Oncology: Research Funding; AmerisourceBergen: Honoraria; Forma Therapeutics: Research Funding; Leukemia and Lymphoma Society: Research Funding; Syndax: Honoraria. Arellano: Syndax Pharmaceuticals, Inc: Consultancy; KITE Pharma, Inc: Consultancy. Schiller: Actinium Pharmaceuticals, Inc: Research Funding; Mateon: Research Funding; Tolero: Research Funding; Geron: Research Funding; Regimmune: Research Funding; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Celator: Research Funding; Sangamo: Research Funding; Stemline Therapeutics, Inc.: Honoraria, Research Funding, Speakers Bureau; Takeda: Research Funding; PrECOG: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Karyopharm: Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gamida Cell Ltd.: Research Funding; FujiFilm: Research Funding; Samus: Research Funding; Trovagene: Research Funding; Daiichi-Sankyo: Research Funding; Constellation Pharmaceuticals: Research Funding; BMS/Celgene: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Abbvie: Research Funding; Actuate: Research Funding; Arog: Research Funding; Delta-Fly: Research Funding; Amgen: Consultancy, Current equity holder in publicly-traded company, Honoraria, Research Funding, Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding; Jazz: Consultancy, Honoraria, Research Funding, Speakers Bureau; Elevate: Research Funding; Ono-UK: Consultancy, Research Funding; Onconova: Research Funding; Deciphera: Research Funding; Astellas: Honoraria, Research Funding, Speakers Bureau; Forma: Research Funding; Genentech-Roche: Research Funding; Bio: Research Funding; Sanofi: Honoraria, Research Funding, Speakers Bureau; Pharma: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Biomed Valley Discoveries: Research Funding; Eli Lilly: Research Funding; ASH foundation: Other: Chair-unpaid; Sellas: Research Funding; Ono: Consultancy; Incyte: Consultancy; Ariad: Research Funding; AstraZeneca: Consultancy; Kaiser Permanente: Consultancy; Cyclacel: Research Funding; MedImmune: Research Funding; Ambit: Research Funding; Leukemia & Lymphoma Society: Research Funding; Bluebird Bio: Research Funding; Boehringer-Ingleheim: Research Funding; Cellerant: Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Kura Oncology: Research Funding; Pharmacyclics: Honoraria, Speakers Bureau; Millennium: Research Funding; National Marrow Donor Program: Research Funding; NIH: Research Funding; Onyx: Research Funding; Pharmamar: Research Funding; UC Davis: Research Funding; UCSD: Research Funding; Evidera: Consultancy; NCI: Consultancy; Novartis: Speakers Bureau. Olin: Astellas: Honoraria, Research Funding; Daiichi Sankyo: Research Funding; Genentech: Research Funding; Pfizer: Research Funding; Cellectis: Research Funding; Amgen: Honoraria; Abbvie: Honoraria; Actinium: Honoraria. Foran: taiho: Honoraria; syros: Honoraria; kura: Research Funding; boehringer ingelheim: Research Funding; sanofi aventis: Honoraria; trillium: Research Funding; aptose: Research Funding; abbvie: Research Funding; pfizer: Honoraria; gamida: Honoraria; actinium: Research Funding; takeda: Research Funding; certara: Honoraria; OncLive: Honoraria; bms: Honoraria; revolution medicine: Honoraria; servier: Honoraria; novartis: Honoraria; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Litzow: AbbVie: Research Funding; Jazz: Other: Advisory Board; Pluristem: Research Funding; Amgen: Research Funding; Omeros: Other: Advisory Board; Actinium: Research Funding; Astellas: Research Funding; Biosight: Other: Data monitoring committee. Lin: AbbVie, Aptevo Therapeutics, Astellas Pharma, Bio-Path Holdings, Celgene, Celyad, Genentech-Roche, Gilead Sciences, Incyte, Jazz Pharmaceuticals, Novartis, Ono Pharmaceutical, Pfizer, Prescient Therapeutics, Seattle Genetics, Tolero, Trovagene: Research Funding. Patel: BMS-Celgene, Agios: Membership on an entity's Board of Directors or advisory committees; Peerview: Honoraria; Aptevo Therapeutics: Research Funding. Foster: Bellicum Pharmaceuticals: Research Funding; Macrogenics: Research Funding; Rafael Pharmaceuticals: Research Funding; Macrogenics: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy. Cogle: Aptevo therapeutics: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees. Vergilio: Foundation Medicine: Current Employment. Gana: The Leukemia & Lymphoma Society: Consultancy; Bausch: Current holder of individual stocks in a privately-held company. Druker: VB Therapeutics: Membership on an entity's Board of Directors or advisory committees; The RUNX1 Research Program: Membership on an entity's Board of Directors or advisory committees; GRAIL: Current equity holder in publicly-traded company; Third Coast Therapeutics: Membership on an entity's Board of Directors or advisory committees; EnLiven: Consultancy, Research Funding; Iterion Therapeutics: Membership on an entity's Board of Directors or advisory committees; Recludix Pharma, Inc.: Consultancy; Pfizer: Research Funding; Merck & Co: Patents & Royalties; Cepheid: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Nemucore Medical Innovations, Inc.: Consultancy; Bristol-Myers Squibb: Research Funding; Blueprint Medicines: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Aptose Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Amgen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ALLCRON: Consultancy, Membership on an entity's Board of Directors or advisory committees; Aileron: Membership on an entity's Board of Directors or advisory committees; Vincerx Pharma: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Vivid Biosciences: Membership on an entity's Board of Directors or advisory committees. Byrd: Novartis, Trillium, Astellas, AstraZeneca, Pharmacyclics, Syndax: Consultancy, Honoraria; Vincerx Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Newave: Membership on an entity's Board of Directors or advisory committees. Levine: Auron: Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy; Ajax: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Membership on an entity's Board of Directors or advisory committees; Isoplexis: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy; Celgene: Research Funding; Roche: Honoraria, Research Funding; Zentalis: Membership on an entity's Board of Directors or advisory committees; Prelude: Membership on an entity's Board of Directors or advisory committees; Mission Bio: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Janssen: Consultancy; Gilead: Honoraria; Morphosys: Consultancy; Imago: Membership on an entity's Board of Directors or advisory committees; QIAGEN: Membership on an entity's Board of Directors or advisory committees; Lilly: Honoraria. Borate: Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Blueprint Medicine: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharma: Research Funding; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rampal: Membership on an entity's Board of Directors or advisory committees; Galecto, Inc.: Consultancy; Promedior: Consultancy.

Background: ENA is an oral, selective inhibitor of IDH2 approved for the treatment (Tx) of patients (pts) with relapsed/refractory IDH2 mutated (IDH2m) AML. Here we report the results of a Phase 2 expansion and Phase 1b of the Beat AML Master Trial Phase 2/1b sub-study to assess the efficacy of Tx of newly diagnosed (ND) IDH2m AML pts ≥ 60 years of age with ENA monotherapy (ENAm) and subsequent response-driven addition of AZA Tx. (ClinicalTrials.gov NCT03013998). Methods: The study initiated with a 3-outcome, 2-stage Phase 2 design, which enrolled patients on ENAm for up to 5 cycles. Pts without CR/CRi after 5 cycles of ENAm, or progression/intolerance prior to this time, were transferred to Phase 1b to receive ENA + AZA (Figure 1). Key eligibility included ND IDH2m AML pts with age ≥ 60 years and ECOG performance status 0-2. Pts received ENAm 100 mg/day in continuous 28-day cycles and ENA + AZA (75 mg/m2 days 1-7 every 28 days) for Phase 1b. Response was assessed using 2017 ELN AML criteria. The primary endpoint was CR/CRi rate. The 2-stage design required 24 pts and tested the null hypothesis (H0) that CR/CRi rate equaled 20% vs 50% and then expanded to test a revised H0 of 30% vs 50% in 60 pts (conditional alpha=0.025, power=77%). Expansion also allowed further assessment of safety of this treatment regimen. Results: At data cut off (06/18/2020), 60 pts enrolled, received ENAm, and were evaluable for the primary endpoint. Median age was 75 years and 52% were female (Table 1). Median time on ENAm was 4.7 months (mos). At data cut off, 12 pts were still on ENAm Tx. Most common reasons for discontinuing ENAm were Tx failure (defined as no response to treatment) (23 or 38%), disease progression (loss of response to treatment) (7 or 12%) and adverse events (AEs; 6 or 10%). Five pts (8%) went to transplant. CR/CRi was achieved in 28 pts (47%; adjusted 95% CI 28-59, unadjusted exact 95% CI 34-60) (Table 2). Responses were higher (p=0.04) among the 44 pts with IDH2 R140 (55%) as compared to the 16 with IDH2 R172 mutation (25%) further supporting distinct biology between these subsets. After a median follow up of 14.6 mos, the median overall survival (mOS) was 24.4 mos (95% CI 10.6-not reached). The median duration of response was not reached with 12 mos estimation of 57% (95% CI 34-75). Overall, 20 ENA-related serious adverse events (SAEs) occurred in 15 pts, the most common was differentiation syndrome (12 or 20%) and 1 had ENA-related SAE of tumor lysis syndrome (1.7%). One pt had ENA-related Grade 5 AE (renal failure/death). Most common AEs of any grade (in ≥20%) were nausea, anemia, and low potassium (Table 3). The 7-day/30-day/60-day deaths observed with ENAm were 2%/5%/11%, respectively. Phase 1b: Seventeen pts had inadequate response to ENAm and transferred to Phase 1b to receive ENA + AZA. Median time on Tx (including ENAm) was 6.2 mos and median time on Tx after pts started ENA + AZA was 2.1 mos (Table 2). Most common reasons for discontinuing ENA + AZA included Tx failure (5 or 29%), disease progression (2 or 12%), transplant, death and AEs (each 2 or 12%). CR/CRi was 41% (exact 95% CI 18-67). After a median follow up of 12.7 mos, the mOS from start of ENA + AZA combination Tx was 8.9 mos. Four ENA-related SAEs occurred in 3 pts on ENA + AZA Tx and the most common was differentiation syndrome (2 or 12.5%). One dose-limiting toxicity (Grade 3 nausea) related to both Txs was observed. Most common AEs (≥20%) of any grade were anemia, low albumin and vomiting (Table 3). One death occurred at day 13 of ENA + AZA. Conclusions: In newly diagnosed pts ≥60 years old with IDH2m AML, ENA had a low early death rate, high CR/CRi rate (47%, adjusted 95% CI 28-59), and yielded durable remissions. The most common unique toxicity with ENA was differentiation syndrome that occurred in 20% of patients. In pts who did not achieve CR/CRi with ENAm, a subset of patients achieved CR/CRi with addition of AZA. This combined approach of serial therapy with ENA monotherapy followed by AZA addition in pts with sub-optimal response resulted in a mOS exceeding 2 years for pts enrolled on study. Further focus on improving response among patients with IDH2 R172 mutations, identifying subsets of pts not responding to ENA monotherapy, and integrating new targeted agents into this treatment regimen are warranted. Figure 1 Disclosures Stein: Syndax: Consultancy, Research Funding; Celgene Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy; Biotheryx: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy. Borate:Genentech: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Research Funding; AbbVie: Other: Investigator in AbbVie-funded clinical trials; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding. Baer:Takeda: Other: Institutional research funding; AbbVie: Other: Institutional research funding; Astellas: Other: Institutional research funding; Forma: Other: Institutional research funding; Kite: Other: Institutional research funding; Oscotec: Other: Institutional research funding; Incyte: Other: Institutional research funding. Kovacsovics:Agios: Honoraria; Astella: Honoraria; Pfizer: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Jazz: Honoraria. Schiller:Astellas Pharma: Honoraria, Research Funding; Celator: Research Funding; Constellation: Research Funding; Abbvie: Research Funding; Actinium: Research Funding; Ariad: Research Funding; Stemline: Speakers Bureau; Cyclacel: Research Funding; Daiichi Sankyo: Research Funding; Deciphera: Research Funding; DeltaFly: Research Funding; Bristol-Myers Squibb: Current equity holder in publicly-traded company, Research Funding; Forma: Research Funding; FujiFilm: Research Funding; Gamida: Research Funding; Genentech-Roche: Research Funding; Geron: Research Funding; Jazz Pharmaceuticals: Research Funding; Karyopharm: Research Funding; Kite Pharma: Research Funding; Mateon: Research Funding; MedImmune: Research Funding; Onconova: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Regimmune: Research Funding; Samus: Research Funding; Sangamo: Research Funding; Tolero: Research Funding; Trovagene: Research Funding; Kaiser Permanente: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Agios: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Incyte: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding; Ono Pharma: Consultancy; Celgene: Research Funding, Speakers Bureau; Sanofi: Speakers Bureau; Gilead: Speakers Bureau. Olin:Astellas: Other: Site PI; Genentech: Other: Site PI; Pfizer: Other: Site PI; Daiichi Sankyo: Other: Site PI; Genentech: Consultancy; Amgen: Consultancy. Foran:Trillium: Research Funding; Xencor: Research Funding; H3Biosciences: Research Funding; Agios: Honoraria, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; Boehringer Ingelheim: Research Funding; Actinium: Research Funding; Aprea: Research Funding; Aptose: Research Funding; Kura Oncology: Research Funding; Takeda: Research Funding; Revolution Medicine: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees. Lin:Trovagene: Research Funding; Tolero Pharmaceuticals: Research Funding; Seattle Genetics: Research Funding; Prescient Therapeutics: Research Funding; Abbvie: Research Funding; Bio-Path Holdings: Research Funding; Astellas Pharma: Research Funding; Aptevo: Research Funding; Incyte: Research Funding; Pfizer: Research Funding; Mateon Therapeutics: Research Funding; Ono Pharmaceutical: Research Funding; Jazz: Research Funding; Gilead Sciences: Research Funding; Genetech-Roche: Research Funding; Celyad: Research Funding; Celgene: Research Funding. Patel:DAVA Pharmaceuticals: Honoraria; Celgene: Consultancy, Speakers Bureau; Agios: Consultancy; France Foundation: Honoraria. Foster:Daiichi Sankyo: Consultancy; Bellicum Pharmaceuticals: Research Funding; Macrogenics: Consultancy, Research Funding. Druker:Leukemia & Lymphoma Society: Research Funding; Henry Stewart Talks: Patents & Royalties; Iterion Therapeutics (formerly Beta Cat Pharmaceuticals): Membership on an entity's Board of Directors or advisory committees; Vivid Biosciences: Membership on an entity's Board of Directors or advisory committees; GRAIL: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Patient True Talks: Consultancy; The RUNX1 Research Program: Membership on an entity's Board of Directors or advisory committees; Third Coast Therapeutics: Membership on an entity's Board of Directors or advisory committees; VB Therapeutics: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millipore (formerly Upstate Biotechnology): Patents & Royalties; MolecularMD (acquired by ICON): Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Novartis Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; McGraw Hill: Patents & Royalties; Merck & Co: Patents & Royalties; Cepheid: Consultancy, Membership on an entity's Board of Directors or advisory committees; Dana-Farber Cancer Institute: Patents & Royalties; EnLiven: Consultancy, Research Funding; Aptose Therapeutics Inc. (formerly Lorus): Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ARIAD: Research Funding; Blueprint Medicines: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; ALLCRON: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Research Funding; Aileron Therapeutics: Membership on an entity's Board of Directors or advisory committees; Pfizer: Research Funding; Oregon Health & Science University: Patents & Royalties. Byrd:Acerta Pharma: Research Funding; Syndax: Research Funding; Vincera: Research Funding; Pharmacyclics LLC, an AbbVie Company, Janssen, Novartis, Gilead, TG Therapeutics: Other; Pharmacyclics LLC, an AbbVie Company, Gilead, TG Therapeutics, Novartis, Janssen: Speakers Bureau; Novartis: Research Funding; Kartos Therapeutics: Research Funding; Trillium: Research Funding; Leukemia and Lymphoma Society: Other; Janssen: Consultancy; Pharmacyclics LLC, an AbbVie Company, Gilead, TG Therapeutics, BeiGene: Research Funding. Levine:Loxo: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Imago: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Research Funding; Qiagen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Prelude Therapeutics: Research Funding; Amgen: Honoraria; Astellas: Consultancy; Morphosys: Consultancy; Novartis: Consultancy; Isoplexis: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Lilly: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Gilead: Honoraria. Mims:Abbvie: Membership on an entity's Board of Directors or advisory committees; Kura Oncology: Membership on an entity's Board of Directors or advisory committees; Leukemia and Lymphoma Society: Other: Senior Medical Director for Beat AML Study; Jazz Pharmaceuticals: Other: Data Safety Monitoring Board; Syndax Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy; Novartis: Speakers Bureau. OffLabel Disclosure: Enasidenib is not approved for the treatment of newly diagnosed AML.

746 Background: Pelareorep is a proprietary formulation of live, replication-competent, naturally occurring Reovirus Type 3 Dearing strain. A randomized phase II trial of pelareorep in combination with carboplatin and paclitaxel in first-line treatment of metastatic PDAC (NCT01280058) was performed. Although pelareorep did not improve the primary endpoint of progression-free survival compared to carboplatin and paclitaxel alone, impressive durable responses were seen in the pelareorep arm in some patients (pts). Further, prior studies have noted the immunomodulatory carcinoembryonic antigen-related cell adhesion molecule (CEACAM6/CD66c) as a receptor for specific viral subtypes. We thus speculated that altered CEACAM6 levels may be predictive for pelareorep sensitivity. Methods: Pre-treatment tissue biopsies were collected prior enrolment for all 73 pts on study. Evaluable pts with transcriptomic data was available for only 31 pts. RNA was purified from FFPE tissue and gene expression analysis was performed using SensationPlus FFPE Amplification and WT labelling kit and the Human Transcriptome Array 2.0. CEACAM6 protein expression was determined by immunohistochemistry. Differential gene expression and survival analysis using were performed in R/Bioconductor. Appropriate corrections for multiplicity were performed. Results: When comparing extraordinary responders in the pelareorep treated arm to those with poor outcomes, low levels of CEACAM6 mRNA expression were associated with prolonged PFS in pelareorep-treated pts (adjusted p = 0.05). This effect was not seen in non-pelareorep treated pts. The luminal, but not the cytoplasmic immunohistochemistry score, was highly correlated with mRNA expression levels of CEACAM6, p = 0.001. Modulation of CEACAM6 in vitro and in vivo are underway. Conclusions: CEACAM6 may be a candidate biomarker of sensitivity to pelareorep and, in theory, could improve viral trafficking of this compound in tumor cells. Clinical trial information: NCT01280058 . [Table: see text]