We present the case of a 64-year-old man diagnosed with large B-cell lymphoma who relapsed twice after standard-of-care therapy. Due to persisting cytopenia, Next generation sequencing analysis was performed, revealing a small TP53-mutated clone. As a third-line therapy, the patient was treated with CAR-T cells, which resulted in complete remission. However, this treatment also led to the expansion of the TP53-mutated clone and therapy-related myelodysplasia with a complex aberrant karyotype. This case may serve as a paradigmatic example of clonal hematopoietic progression in a patient undergoing CAR-T cell therapy, especially in the context of a TP53-mutated clone.

Background: Relapsed/refractory (R/R) acute myeloid leukemia (AML) is a largely unmet medical condition with limited treatment options and dismal prognosis. In newly diagnosed AML patients (pts), a modified risk stratification based on the mutational status of four genes (FLT3-ITD, KRAS, NRAS and TP53) indicated distinct benefit from treatment with azacitidine and venetoclax (Döhner et al. ASH 2022). However, the role of venetoclax (VEN) in R/R AML is not well defined yet and predictors of response are unclear. Aims: To identify predictors of response and survival of off-label VEN+non-intensive therapy in pts with R/R AML reported to the venetoclax registry (NCT03662724). Methods: We retrospectively analyzed clinical characteristics and outcomes of R/R AML pts treated with VEN-based non-intensive treatment-regimens between February 2017 and February 2023. Cytogenetic and molecular studies were performed at the time of refractory or relapsed AML by conventional karyotyping and next-generation sequencing. Mutations associated with myeloid leukemias were detected using a custom myeloid sequencing panel, which included 48 genes. VEN was combined with either azacitidine, decitabine or LDAC. The overall response rate (ORR) was defined by complete remission (CR) + CR with incomplete hematologic recovery (CRi) + morphologic leukemia-free state (MLFS). Data cut-off was February 21, 2023. Results: One-hundred-sixty-three pts with either relapsed (n=67, 41%) or refractory (n=81, 50%; missing 9%) AML and a median age of 70 years (range, 24-86) were included in our analysis. Prior treatment lines included intensive chemotherapy (61%), HMA treatment (58%) and allogeneic transplantation (33%). ELN2017 risk was intermediate and adverse in 31% and 55% of pts in this high-risk cohort. Forty-five pts (28%) had complex cytogenetics and seventeen pts (10%) had extramedullary disease manifestation. In total, 29 genes were found mutated in ≥5 pts. The overall response rate (ORR) was 44% (n=77), including 38% of pts achieving CR/CRi and 6% MLFS. After a median follow-up of 25.9 months (mo), median overall survival (OS) and median event-free survival (EFS) was 8.4 mo (95% CI, 5.7-11.04) and 4.8 mo (95% CI, 3.6-6), respectively. Clinical predictors of survival included age above the median age (≥70 years vs. <70 years 6.4 vs. 10 mo, p=0.07), HMA pretreatment (pretreatment vs. no pretreatment 6.0 vs. 10.2 mo, p=0.02), extramedullary disease manifestation (present vs. absent 5.0 vs. 9.3 mo, p=0.01). A modified risk model was constructed based on the mutational status of nine genes that were associated with survival. Pts were classified into three risk groups with significantly different OS based on mutated STAG2, BCOR or SF3B1 (favorable risk; median OS 17.5 mo), mutated TP53, any FLT3, CBL, PTPN11 or NF1 mutation (adverse risk; median OS 4.6 mo), and all other pts (intermediate risk; median OS 9.6 mo; p<0.001) (Figure 1). This risk score was also prognostic for EFS and ORR. In multivariate analysis the genetic R/R AML VEN risk model (p<0.001), extramedullary disease (p=0.02), and HMA pretreatment (p=0.01) remained significant predictors of inferior survival. Summary/Conclusion: This real-world analysis comprising a large cohort of R/R AML pts treated with VEN-based non-intensive therapies identifies the presence of extramedullary disease and HMA pretreatment as clinical predictors of inferior survival. Further, our data suggest a novel prognostic risk classification based on the mutational status of nine genes with significant OS, EFS and ORR distinction. The genetic R/R AML VEN risk score requires independent validation. Figure 1Keywords: Real world data, Molecular markers, Venetoclax, Acute myeloid leukemia

Introduction: The 2022 International Consensus Classification (ICC) stresses the importance of molecular- and cytogenetic aberrations over previous medical history. Nine mutations are used to define a subgroup of AML with myelodysplasia related gene mutations (AML-MRGM). On a lower hierarchical level specific cytogenetic changes are used to define a subgroup of AML with myelodysplasia related cytogenetic abnormalities (AML-MRCA). Both groups together with TP53 mutations are categorized within the adverse risk group of the 2022 ELN classification. We evaluated the prognostic implications of clonality of MRGM mutations. Methods: 552 newly-diagnosed adult AML patients (pts.) with a median age of 55 years who received intensive induction chemotherapy followed by consolidation chemotherapy or allogeneic stem cell transplantation and with available genetic and follow-up data were included. Mutations present at diagnosis were identified by Illumina myeloid panel sequencing covering 48 AML-associated genes. Variant allele frequency (VAF) was adjusted for sex for mutations located on the X chromosome (BCOR, STAG2, ZRSR2). The prognostic VAF cutoff was identified by maximally selected rank statistics. We defined AML-MRGM as having at least one MRG mutation, AML-MRCA as having at least one MRCA without MRGM, TP53 mutated patients as having TP53 mutations regardless of the presence of MRGM or MRCA and for the remaining pts. de novo AML and secondary/therapy-related AML according to medical history of the patient. For multivariate analysis value imputation was used for missing values. Results:40 (7.2%) of 552 pts. were TP53 mutated,196 (35.5%) had at least one MRGM, and 47 pts. (8.5%) had MRCA. Among the clinically defined cases 215 pts. (38.9%) had genuine de novo AML and 54 (9.8%) had a previous history of a hematologic malignancy or cytotoxic treatment. The median follow-up was 5.8 years. Overall survival (OS) and relapse free survival (RFS) for de novo AML and secondary AML based on medical history were not significantly different and were therefore grouped together as clinically-defined AML (cdAML). AML-MRGM pts. had a significantly lower complete remission (CR) rate (OR=0.32, 95%CI 0.18-0.56, p<0.001) and shorter OS, but not RFS, compared to cdAML pts. (OS, HR 1.38, 95%CI 1.04-1.83, p=0.02; RFS, HR 1.12, 95%CI 0.84-1.48, p=0.44). AML-MRCA had similar OS and RFS compared to both cdAML and AML-MRGM pts., but a significantly better CR rate than AML-MRGM pts. (OR 5.68, 95%CI 1.64-38.65, p=0.01). Pts. with TP53 mutations had a worse OS and RFS than all other subgroups. A VAF of 45% was identified as a prognostic cutoff by maximally selected rank statistics. Patients with MRGM and VAF ≥ 45% were associated with higher age (p=0.04) and a lower platelet count at diagnosis (p=0.04). A VAF ≥ 45% was identified in 81 pts. (41.3%) and was associated with a significantly worse OS and RFS compared to the 115 pts. (58.7%) with a VAF below 45% (OS, HR 1.70, 95%CI 1.12-2.57, p=0.01; RFS, HR 1.65, 95%CI 1.05-2.57, p=0.03) (Figure 1). Patients with VAF ≥ 45% had an OS and RFS similar to AML-MRCA pts., but significantly shorter OS and RFS than cdAML pts. (OS, HR 1.89, 95%CI 1.32-2.69, p<0.001; RFS, HR 1.52, 95%CI 1.04-2.21, p=0.03). In multivariate analysis the presence of MRGM with a VAF ≥45% was an independent adverse prognostic factor for OS. Conclusion: In the present study, we confirm myelodysplasia-related gene mutations and TP53 mutations as negative prognostic markers in line with the hierarchical significance proposed by ELN. Our study suggests that the presence of MRGM is associated with worse OS especially if it is present at a VAF ≥ 45%, likely representing patients with at least one MRG mutation in the major AML clone.

In myeloma patients, high levels of soluble BCMA (sBCMA) can limit the efficacy of BCMA-directed therapies. Belantamab-mafodotin is a BCMA antibody-drug conjugate and shows good overall response rates in heavily pretreated patients but progression-free survival data are poor. As the drug induces apoptosis, we hypothesized that sBCMA includes extracellular vesicles (EV) and thus evaluated numbers of BCMA-EV before and during belantamab therapy in 10 myeloma patients. BCMA-EV were significantly higher in patients prior to Belantamab (median: 3227/μl; p = .013) than in other myeloma patients before therapy (n = 10; 1082/μl) or healthy volunteers (n = 10; 980/μl). During therapy, BCMA-EV showed a significant increase to a maximum of 8292/μl (p = .028). Maximal changes in BCMA-EV (Δmax = BCMA-EV at C1/maximal BCMA-EV) showed a strong inverse, logarithmic correlation (r = -.950; p < .001) with FLC ratio changes (Δmax = FLC ratio at C1/minimal FLC ratio) and BCMA-EV peaks often preceded FLC progression. Correlating increase of LDH and BCMA-EV levels, together with clinical symptoms, point to a mafodotin-induced eryptosis. In summary, BCMA-EV are a part of sBCMA, peak levels precede progression, and their measurement might be helpful in identifying resistance mechanisms and side effects of BCMA targeted therapies.

Introduction: Measurable residual disease (MRD) plays an increasing role for treatment management of AML patients. While next-generation-sequencing (NGS) based MRD assessment can be well standardized, there is uncertainty about the type of gene mutations that associate with prognosis and are useful for MRD assessment. The 2022 ELN recommendations assign patients with at least one mutation in the genes ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1 or ZRSR2 to the subgroup of myelodysplasia-related gene mutations (MRGM), which is associated with poor prognosis. We aimed to define the prognostic effect of MRD after induction chemotherapy in AML patients with MRGM using MRG mutations for MRD assessment by NGS. Methods: We retrospectively collected bone marrow and peripheral blood samples from AML patients in complete remission (CR) or CR with incomplete hematologic recovery (CRi) after one to two cycles of 7+3-based standard induction chemotherapy (IC) with at least one MRGM detected at diagnosis by myeloid panel sequencing covering 48 AML associated genes. Patients treated with one course of IC were included if they proceeded to allogeneic hematopoietic cell transplantation (alloHCT) already after one cycle. Molecular MRD status was assessed using targeted NGS and bioinformatics error-correction with 0.01% sensitivity as described before using only MRGM as MRD markers. Results: MRD was assessed on 104 adult newly-diagnosed AML patients (median age 58.6) with a total of 166 MRGM, resulting in a median of one MRGM per patient (range 1-4). 43 (41.3%) patients had secondary or therapy-related AML and 20 (19.2%) had myelodysplasia-related cytogenetic abnormalities. 68 (65.4%) patients were MRD positive for at least one MRGM after one (18 patients (17.3%)) or two (86 patients (82.7%)) cycles of intensive chemotherapy, while 36 (34.6%) became MRD negative. Measured variant allele frequencies (VAF) of positive samples ranged from 0.02-43.1% (median VAF 1.34%).MRD positive patients were older and more likely to be male compared to MRD negative patients, while cytogenetic risk, WBC count, Hgb, platelet count and ECOG status at diagnosis were similar to MRD negative patients. 53 (77.9%) MRD positive and 23 (63.9%) MRD negative patients underwent alloHCT in first CR/CRi.Median follow-up was 3.35 years. OS (P = 0.92), RFS (P = 0.99) and CIR (P = 0.98) were similar in MRD positive (at least one MRGM detectable) and negative (no MRGM detectable) patients (Figure 1). OS, RFS and CIR were also similar between MRD positive and negative patients, when MRD negativity was defined by conversion of at least one MRGM to negativity (55 (52.9%) MRD positive, 49 (47.1%) MRD negative), and when ASXL1 was excluded from the analysis. As variants with VAF >5% in CR/CRi samples may indicate clonal hematopoiesis, we excluded all variants with VAF >5% and repeated the analysis with the 88 (84.6%) remaining patients. Again, OS, RFS and CIR were similar for MRD positive and negative patients. We next reasoned that reduction of VAF correlates with the sensitivity of leukemic cells and possibly with depth of remission and long-term outcome. The fold-reduction of VAFs from diagnosis to the time of MRD analysis was calculated for all variants. For patients with several MRGMs, the variant with the largest fold-reduction was considered including undetectable variants. Patients with more or less than a 2-log, 3-log or 4-log reduction (log 10) had similar OS, RFS and CIR, respectively. Evaluating each MRGM individually, only RUNX1-MRD associated with RFS and by trend CIR (comparing MRD positive to negative patients for OS, HR 3.41, 95% CI 0.43-26.82, P = 0.24; RFS, HR 4.37, 95% CI 1.07-17.79, P = 0.04; CIR, HR 3.30, 95% CI 0.79-13.82, P = 0.1). Conclusion: 65.4% of AML-MRGM patients in CR/CRi remained MRD positive when MRGMs were used for MRD assessment by NGS. MRD positivity was associated with age above 60 years and male sex.Using all MRG mutations for MRD assessment at a threshold of 0.01% or by various degrees of log-reduction was not predictive of outcome after intensive induction chemotherapy. This limits the number of potential MRD markers for NGS analysis before alloHCT, although individual markers like RUNX1 may be of prognostic value.

Outcome in younger patients (pts) with ALL has been improved considerably using intensive pediatric-based therapy, but limited data on this approach have been reported for older pts and even the age cut-off is heavily debated. The German Multicenter Center Study Group for Adult ALL (GMALL) has conducted a clinical trial (>55 years) (NCT00198978) which was followed by a registry trial based on standard management recommendations with prospective documentation in the GMALL registry (NCT02872987). Strategies were modified over the years (yrs). The backbone included: Pre-phase (Dexa, Cyclo), induction I (Dexa, VCR, Idarubicine), induction II (Cyclo, AraC), ±post-induction PEG-ASP, consolidation (C) cycles with IDMTX (± E.coli ASP), HDAraC (earlier: VM26), reinduction (VCR, Idarubicine, Cyclo, AraC), ± Rituximab in CD20+, i.th. prophylaxis and maintenance (6-MP/MTX) (group 1). The latest protocol (from 2017) additionally included IDMTX/PEG-ASP in consolidation and recommended MRD-based treatment modification (Blinatumomab in B-Lin and Nelarabin in T-Lin) in molecular failure (MolFail) after C2 (group 2). 882 patients (pts) from 142 sites were included 2003-2021 (table 1). 5% were withdrawn early and therefore not evaluable. The median age was 68 (56-86) yrs. 61% were older than 65 yrs. B-Lin-ALL was present in 68%; 7% of B-Lin-ALL (N=45) had a KMT2A-rearrangement. 19% and 9% had immature subtypes, pro-B and early T-ALL resp.. 50% had at least one comorbidity according to the Charlson-Score (ChS); 11% had a score ≥3; 28% had an BMI≥30 mg/m2. Group 2 vs group 1 had a significantly lower median age (66 vs 68 yrs; p=.001) and a higher proportion of T-ALL (21% vs 14%; p=.0003). In 841 pts the CR rate after induction was 73% with 14% early death (ED) and 13% failure. The ED rate was lower in group 2 vs group 1 (9% vs 15%; p=.04). CR rates were 76%, 73% and 63% in three age groups (56-65, 66-75, ≥76 yrs) with ED rates of 9%, 14% and 26% resp. (p<.0001). CR rates were significantly lower in pts with WBC ≥30.000/µl (table 1). BMI (≥30 kg/m2) was not associated to CR/ED but ED rates were correlated to ChS with a high ED rate (26%) in those with ChS ≥3 (table 1). MRD response data were available in 163, 239 and 173 pts after induction II, C1 and C2 resp. The molecular CR (MolCR)/ MolFail rates were 41%/52%, 57%/38% and 64%/30% resp. The remaining pts had intermediate MRD (MolIMR). MolCR rates were similar in B-Lin only (43%/58%/64%). With a median follow up of 2.7 yrs overall survival (OS) in 841 pts at 3, 5 and 10 yrs was 36%, 28% and 22% resp. The 3y remission probability was 37%. Mortality in CR was 5% (3%, 6% and 7% by age) and 12% of the pts were withdrawn from protocol. OS strongly correlated to age and was very poor in pts older than 75 yrs (7% at 3 yrs; table 1). Only 8% (N=51) of all CR pts received an allogeneic stem cell transplantation (SCT) in CR1 (N=20 ≥65 yrs) but the SCT-rate increased in group 2 vs group 1 (9% vs 5%). 3y-OS after SCT in this selected group (N=51) was 56%. OS was significantly superior in group 2 vs group 1 (50% vs 32%; p<0.001) (figure 1). This improvement occurred mainly in the younger age group (56-65 yrs): 62% vs 38% 3y OS in group 2 vs group 1 resp. (p<0.0001) with no significant improvement in pts older than 65 yrs. WBC and ChS≥3 were associated with poorer OS (table 1). MRD response had a significant impact on OS at all timepoints. Pts with MolCR after C1 had a 3 yr OS of 80% vs 52% for MolFail and 62% for MolIMR (p=.0004). Interestingly the 3y-OS of 52 MolFail pts tended to be superior in group 2 (74% vs 46%;p>.05). The CR rate and OS of MLL-rearranged cases was 62% and 19% resp. With this age-adapted, pediatric-based regimen a reasonable CR rate was achieved up to 75 yrs. Pt numbers were small and OS very poor in pts >75 yrs. MolCR rates were overall lower compared to more intensive protocols in younger pts. Thus, treatment modification based on MolFail is a promising approach and might produce benefits in many older pts. The optimal time-point for treatment change remains to be defined. Together with more intensive consolidation including PEG-ASP this modification likely contributed to the improved outcome with 62% OS in the youngest cohort (56-65 yrs) in group 2. In all older pts, but specifically in those >65-75 yrs or with multiple comorbidities, alternative protocols with targeted therapies and further step-wise reduction of chemotherapy require prospective exploration in clinical trials with the major goal to reduce ED rate and to improve MRD response. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Resistance mutations can be detected in 75% of CLL patients progressing under BTK inhibitor therapy. Using semiquantitative wild-type-blocking (WTB) RT-PCR for BTK and Sanger sequencing for PLCG2 mutations, we compared detection sensitivity of cellular versus circulating tumor DNA (ctDNA) in 20 sample pairs of 13 consecutive patients. With an assay sensitivity of 0.06%, 7 patients had a BTK-C481S and one a PLCG2-G667E mutation. Cellular DNA was positive in 10 but ctDNA only in 6 samples, giving false-negative results in samples with low mutational burden. In summary, WTB-PCR is cost-effective and routinely applicable but misses low frequency mutations when using ctDNA.

e21076 Background: Results of IMpower-150 and Orient-31 have demonstrated a favorable effect of combining anti-angiogenic therapy and checkpoint inhibition for refractory NSCLC patients with EGFR mutations. However, both studies included only very few patients with uncommon EGFR mutations, not allowing further analysis. For those patients, representing about 10% of EGFR mutant NSCLCs, treatment options are still limited. Methods: Analysis included 16 stage IV NSCLC patients with uncommon EGFR mutations from 9 different German centers which started treatment in first or further line with Atezolizumab, Bevacizumab, Carboplatin and (nab-)Paclitaxel (ABCP) between October 2018 and January 2022. EGFR mutations were detected by NGS (n = 15) or COBAS-PCR (n = 1). PFS was evaluated from start of ABCP and OS from time of initial diagnosis of stage IV. Results: 5 men and 11 women received ABCP therapy in first (n = 4), second (n = 9) or further line (n = 3). Mean age was 56 (36-77) years. Patients had either an Exon 20 insertion (n = 9) or point mutation (n = 2, S768I), an Exon 18 mutation (n = 3, G719X or E709A), an Exon 21 mutation (L861Q) or a compound mutation (G719C/S768I). 9 patients received a TKI therapy in first line (4x Afatinib; 5x Osimertinib) with an ORR of 66.7% (CR = 1; PR = 5; SD = 1; PD = 2) and a median time-to-next-treatment of 6.7 months (range: 2.1-39.1 months). Median number of full ABCP cycles were 4 (1-6), with 3 patients (23.1%) requiring a dose reduction of chemotherapy and 4 patients (30.8%) suffering from grade 3 or 4 toxicity (one immune related pneumonitis). 13 patients (84.6%) received a maintenance with AB and the median follow-up after initial diagnosis was 19.6 months (2.3-38.4). ORR was 81.3% with 2 CR, 11 PR, 1 SD and 1 PD (not available = 1). Median PFS by Kaplan-Meier analysis was 13.0 months for both the entire cohort (95%-CI: 8.4-17.6) and for Exon 20 insertions (95%-CI: 9.3-16.7). Corresponding median OS was either not reached or 30.7 months (95%-CI: 13.8-47.6). Landmark analysis at 12 months gave a PFS of 42.8% and an OS of 93.3%. Univariate Cox regression showed no association of PFS or OS with patient or treatment parameters, including PD-L1 expression, type of mutation or prior TKI treatment. 4 patients were rechallenged with ABCP while progressing under AB maintenance and responded again. 4 patients received mobocertinib as further treatment, but only one showed a clinical benefit. Conclusions: In this retrospective analysis, ABCP achieves an encouraging outcome for patients with uncommon EGFR mutations, comparable to results for common EGFR mutations in IMpower150 (ORR 71%, mPFS: 9.7 months, mOS 29.4 months). This in contrast to immunotherapy alone which shows poor ORR and PFS. Together with new targeted treatment options for Exon 20 insertions like amivantamab (ORR 40%, mPFS 8.3 months) or mobocertinib (ORR 28%, mPFS 7.3 months), ABCP is a valuable option in the early course of treatment for this patient cohort.

msAML-defining mutations identify a subgroup of dnAML patients with poor prognosis and reclassify 10% of all patients in our cohort from favorable/intermediate to the adverse risk group.

The antibody-drug conjugate polatuzumab vedotin (pola) has recently been approved in combination with bendamustine and rituximab (pola-BR) for patients with refractory or relapsed (r/r) large B-cell lymphoma (LBCL). To investigate the efficacy of pola-BR in a real-world setting, we retrospectively analyzed 105 patients with LBCL who were treated in 26 German centers under the national compassionate use program. Fifty-four patients received pola as a salvage treatment and 51 patients were treated with pola with the intention to bridge to chimeric antigen receptor (CAR) T-cell therapy (n = 41) or allogeneic hematopoietic cell transplantation (n = 10). Notably, patients in the salvage and bridging cohort had received a median of 3 prior treatment lines. In the salvage cohort, the best overall response rate was 48.1%. The 6-month progression-free survival and overall survival (OS) was 27.7% and 49.6%, respectively. In the bridging cohort, 51.2% of patients could be successfully bridged with pola to the intended CAR T-cell therapy. The combination of pola bridging and successful CAR T-cell therapy resulted in a 6-month OS of 77.9% calculated from pola initiation. Pola vedotin-rituximab without a chemotherapy backbone demonstrated encouraging overall response rates up to 40%, highlighting both an appropriate alternative for patients unsuitable for chemotherapy and a new treatment option for bridging before leukapheresis in patients intended for CAR T-cell therapy. Furthermore, 7 of 12 patients with previous failure of CAR T-cell therapy responded to a pola-containing regimen. These findings suggest that pola may serve as effective salvage and bridging treatment of r/r LBCL patients.

Introduction The antibody-drug conjugate polatuzumab vedotin (Pola) has recently been approved in combination with bendamustine and rituximab (Pola-BR) for patients with r/r diffuse LBCL (DLBCL). Methods To characterize the efficacy of Pola-BR in a real-world setting, we retrospectively analyzed data from 97 patients with r/r LBCL who were treated with Pola in 24 German centers within the national CUP. Clinical baseline and follow-up (FU) data were collected by chart review and summarized descriptively. Progression-free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier and Cox regression methods. Fisher's exact test was used to compare categorical factors between groups of patients. Results 97 patients with LBCL (DLBCL n=90, High-grade B-cell lymphoma n=6, Primary mediastinal B-cell lymphoma n=1) were included as of July 22nd, 2020. 49 patients were treated with Pola as bridging concept to immunotherapies (bridging cohort: chimeric antigen receptor T-cells (CART) n=39, allogeneic stem cell transplantation (alloSCT) n=9, bispecific antibodies n=1), and 48 patients were treated with Pola in palliative intention (palliative cohort). Within the bridging cohort the median age was 61 years (range: 22-82). Patients were heavily pretreated with a median of 3 treatment lines (range: 2-6). 84% (41/49 patients) had been refractory to their last treatment line, and 31% had failed an autologous stem cell transplantation. Notably, 14% and 10% of patients had failed prior CART and alloSCT, respectively, and were planned for the alternate cellular immunotherapy. Based on an individual decision, patients were treated with Pola-Rituximab (Pola-R, n=20), Pola-chemotherapy (Pola-chemo, BR n=25; R-CHP n=1) or Pola-monotherapy (Pola-mono, n=3). With a median of 2 Pola cycles (range 1-6), overall response rate (ORR) of all evaluable patients was 33% (15/46 patients) including patients with complete response (CR n=1), partial response (PR n=9) and clinical response (n=5). Although not significant, ORR tended to be better in patients treated with Pola-chemo versus Pola-R/Pola-mono (ORR: 42% versus 20%, Fishers test p=0.1). 11 of these 15 responders (24% of the entire bridging cohort) proceeded to CART or alloSCT, while 4 responders (8% of entire bridging cohort) experienced fast progression after their initial response and were referred to best supportive care. 15 of 31 non-responders (33% of entire bridging cohort) underwent immunotherapy with either stable disease (n=6), mixed response (n=2), or progression on Pola (n=7). The remaining 16 patients (35% of entire bridging cohort) were all refractory to Pola and either received alternative salvage treatments which enabled 8 further patients to proceed to the intended immunotherapy, or best supportive care. Taking the effects of CART or alloSCT into account, median OS from initiation of Pola treatment was 8.2 months (median FU 7.2 months, Fig. 1A). The palliative cohort tended to be older than the bridging cohort with a median age of 73.5 years (range: 37-86, p<0.001). Patients were pretreated with a median of 3 treatment lines (range: 2-8), and 85% (41/48 patients) had been refractory to their last treatment line. Patients in the palliative cohort were treated with a median of 4 Pola cycles (range: 1-9). 65% received Pola-chemo (BR, n=30; R-Gemcitabine, n=1) and 35% Pola-R. The CR rate and ORR was 19% (9/48) and 56% (27/48), respectively. The 6-month PFS and OS from initiation of Pola was 36% and 51%, respectively (median FU of 9.7 months, Fig. 1B). Again, ORR and OS tended to be better in patients treated with Pola-chemo versus Pola-R (ORR: 61% versus 47%, Fishers test p=0.4; median OS 7.2 versus 4 months, HR 0.8, 95%CI 0.4-1.9, p=0.7). In univariate analysis, failure to respond to the last treatment line predicted inferior PFS (HR 2.4, 95%CI 1.2-5.0 p=0.02) and OS (HR 2.5, 95%CI 1.2-5.4 p=0.02). Patients with more than two prior treatment lines in total tended to have a shorter PFS (HR 2.0, 95% CI 0.9-4.5, p=0.1) and OS (HR 1.8, 95% CI 0.8-4.0, p=0.2), although significance was not reached. Conclusion Pola permits effective bridging to CART and alloSCT in r/r LBCL. In the palliative setting, Pola represents an effective salvage option for patients with transplantation-ineligible r/r LBCL. Compared to the approval study, the inferior outcome of the patients of this real-world analysis might be explained by their more advanced disease course. Disclosures Duell: Morphosys: Research Funding. Kerkhoff:BMS: Honoraria. Leng:Roche: Other: lecture fee; Celgene: Other: traveling expenses and congress attendance fee. Holtick:Miltenyi Biotec B.V. & Co. KG: Honoraria. Mayer:Amgen: Honoraria, Other: travel grants; Abbvie: Other: travel grants; Novartis: Honoraria; Roche: Honoraria. Hüttmann:Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Gilead: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Roche: Other: Travel expenses; Seattle Genetics: Research Funding; University Hospital Essen, University of Duisburg-Essen, Essen, Germany: Current Employment; Lead Discovery Center GmbH: Consultancy. Brunnberg:Gilead: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: travel grants; MSD: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Amgen: Other: Travel grants. Bullinger:Menarini: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Hess:Roche: Research Funding; Celgene: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Genmab: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; EUSA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Morphosys: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mueller-Tidow:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Deutsche Krebshilfe: Research Funding; BMBF: Research Funding; Wilhelm-Sander-Stiftung: Research Funding; Jose-Carreras-Siftung: Research Funding; Bayer AG: Research Funding; Daiichi Sankyo: Research Funding; BiolineRx: Research Funding; Janssen-Cilag Gmbh: Membership on an entity's Board of Directors or advisory committees; Deutsche Forschungsgemeinschaft: Research Funding. Lenz:Verastem: Research Funding; AQUINOX: Research Funding; BMS: Consultancy; AstraZeneca: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Agios: Research Funding; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy; Morphosys: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau. Dreger:Roche: Consultancy, Speakers Bureau; Neovii: Research Funding; AbbVie: Consultancy, Speakers Bureau; AstraZeneca: Consultancy; Gilead: Consultancy, Speakers Bureau; Janssen: Consultancy; Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau. Dietrich:Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; KITE: Membership on an entity's Board of Directors or advisory committees.

Introduction: The combination treatment of venetoclax (VEN) with both low-dose cytarabine (LDAC) and hypomethylating agents (HMA) in untreated primarily elderly AML patients yielded promising response rates leading to its approval for newly diagnosed AML patients who are 75 years or older, or who have comorbidities that preclude use of intensive induction chemotherapy. Prolonged cytopenias are of potential concern in venetoclax treated patients, especially in patients who underwent allogeneic hematopoietic cell transplantation (alloHCT) prior venetoclax treatment. Objective: To compare hematologic recovery in patients treated with VEN in combination with intensive and non-intensive chemotherapy regimens for the treatment of relapsed or refractory (R/R) acute myeloid leukemia (AML) depending on the pretreatment status for alloHCT. Methods: In this retrospective controlled study (www.clinicaltrials.gov NCT03662724), we included patients aged 18 years or older with R/R acute leukemia previously treated with VEN (days 1-7) combined with intensive salvage chemotherapy (fludarabine, cytarabine, idarubicin - FLAVIDA) or VEN combined with non-intensive regimens, namely HMA or LDAC. Eighty-one patients who were treated with FLA-IDA for R/R AML served as control for the intensively treated patients included in this analysis. Responses were evaluated per revised International Working Group criteria for AML. Main outcome measure was the rate of objective response (complete remission [CR] + CR with incomplete blood count recovery [CRi] + partial remission [PR] + morphologic leukemia-free state (MLFS; defined as less than 5% blasts in an aspirate sample). Safety and efficacy analyses included all patients who received at least one cycle of VEN combination treatment. This study was approved by the local Ethics Review Committee in accordance with the Declaration of Helsinki. Results: Between January 2017 and May 2019 49 patients with a median age of 59 years (range 18-80) received VEN with either FLA-IDA (n=14), HMA (n=31) or LDAC (n=4) and had safety and efficacy outcomes reported. The patient cohort was a high-risk cohort of relapsed (n=24) and refractory (n=25) patients. The analysis included 24 patients (49%) with secondary AML and two patients with biphenotypic acute leukemia (BAL). Twenty-two patients (45%) had received prior alloHCT and 7 (14%) had relapsed <12 months after transplantation. Twelve patients (25%) had complex cytogenetics and 42 (86%) had intermediate or poor risk AML according to ELN 2017 criteria. The ORR in the 35 non-intensively treated patients was 57% (n=20) with 17 complete responses (49%, CR/CRis), 2 MLFS, and one PR. One patient died before first assessment. Response rates were similar in patients with and without prior alloHCT (ORR 56% vs. 58%). In non-intensively treated responding patients the median time to neutrophil (≥1.0x109/L) and platelet recovery (≥100x109/L) was 42 and 41 days, respectively. No differences in recovery times were observed between patients with and without prior alloHCT (39 vs. 46 days for neutrophil recovery; 41 vs. 52 days for platelet recovery (Fig.1A-B)). For intensively treated patients the ORR was 79% (n=11) with 9 CR/CRis (64%), one MLFS, and one PR compared to an ORR of 47% in the FLA-IDA control cohort. Median time to neutrophil (≥1.0x109/L) and platelet recovery (≥100x109/L) in intensively treated responding patients were 34 and 36 days compared to 39 and 41 days in the control cohort. Median recovery times in patients with and without prior alloHCT were similar (FLAVIDA: 34 vs. 33 days for neutrophil recovery; 36 vs. 36 days for platelet recovery, Fig. 1 C-D; FLA-IDA control: 41 vs. 38 days for neutrophil recovery; 70 vs. 38 days for platelet recovery, Fig. 1 E-F). After a median follow-up of 10.5 months the median overall survival (OS) was 8 months in non-intensively treated patients. After a median follow-up of 9.9 months the median OS was not reached in intensively treated patients. Median event-free survival was 5.8 months in non-intensively treated patients and was not reached in intensively treated patients. Conclusions: Venetoclax in combination with intensive chemotherapy as well as non-intensive regimens showed promising response rates for treatment of relapsed or refractory AML with good tolerability and acceptable duration of cytopenias with no differences in recovery times in patients with and without prior alloHCT. Disclosures Koenecke: Novartis: Other: none. Heuser:Bayer Pharma AG, Berlin: Research Funding; Synimmune: Research Funding.

Outcome of adult ALL has improved considerably during the past decades by intensive chemotherapy, which still remains a challenge in older pts. This may be partly due to comorbidities. So far there are no standards to differentiate pts who will be able to tolerate even age-adapted chemotherapy (fit vs unfit). In addition, little is known about the prevalence of comorbidities. Clinical trials with new compounds often represent a selection of pts w/o comorbidities. There is also no generally accepted tool for comorbidity scoring. The goal of this analysis is to provide reference data for pre-existing comorbidities in a large set of adult ALL pts, to compare two different tools and to evaluate the impact on early death (ED) in older pts.

Background: ADGRE2, CCR1, CD70, and LILRB2 expressed on the surface of myeloid blasts but not normal hematopoietic stem cells, T cells or other tissues have been recently suggested as candidate chimeric antigen receptor (CAR) targets for engineered T cells in acute myeloid leukemia (AML) patients.

Dyskeratosis congenita (DKC) is associated with impaired telomere maintenance and with clinical features of premature aging. In this study, we analysed global DNA methylation (DNAm) profiles of DKC patients. Age-associated DNAm changes were not generally accelerated in DKC, but there were significant differences to DNAm patterns of healthy controls, particularly in CpG sites related to an internal promoter region of PR domain containing 8 (PRDM8). Notably, the same genomic region was also hypermethylated in aplastic anemia (AA) - another bone marrow failure syndrome. Site-specific analysis of DNAm level in PRDM8 with pyrosequencing and MassARRAY validated aberrant hypermethylation in 11 DKC patients and 27 AA patients. Telomere length, measured by flow-FISH, did not directly correlate with DNAm in PRDM8. Therefore the two methods may be complementary to also identify patients with still normal telomere length. In conclusion, blood of DKC patients reveals aberrant DNAm patterns, albeit age-associated DNAm patterns are not generally accelerated. Aberrant hypermethylation is particularly observed in PRDM8 and this may support identification and classification of bone marrow failure syndromes.