FLT3 and IRAK4 Inhibitor Emavusertib in Combination with BH3-Mimetics in the Treatment of Acute Myeloid Leukemia.

Targeting the FLT3 receptor and the IL-1R associated kinase 4 as well as the anti-apoptotic proteins MCL1 and BCL2 may be a promising novel approach in the treatment of acute myeloid leukemia (AML). The FLT3 and IRAK4 inhibitor emavusertib (CA4948), the MCL1 inhibitor S63845, the BCL2 inhibitor venetoclax, and the HSP90 inhibitor PU-H71 were assessed as single agents and in combination for their ability to induce apoptosis and cell death in leukemic cells in vitro. AML cells represented all major morphologic and molecular subtypes, including FLT3-ITD and NPM1 mutant AML cell lines and a variety of patient-derived AML cells. Emavusertib in combination with MCL1 inhibitor S63845 or BCL2 inhibitor venetoclax induced cell cycle arrest and apoptosis in MOLM-13 cells. In primary AML cells, the response to emavusertib was associated with the presence of the FLT3 gene mutation with an allelic ratio >0.5 and the presence of NPM1 gene mutations. S63845 was effective in all tested AML cell lines and primary AML samples. Blast cell percentage was positively associated with the response to CA4948, S63845, and venetoclax, with elevated susceptibility of primary AML with blast cell fraction >80%. Biomarkers of the response to venetoclax included the blast cell percentage and bone marrow infiltration rate, as well as the expression levels of CD11b, CD64, and CD117. Elevated susceptibility to CA4948 combination treatments with S63845 or PU-H71 was associated with FLT3-mutated AML and CD34 < 30%. The combination of CA4948 and BH3-mimetics may be effective in the treatment in FLT3-mutated AML with differential target specificity for MCL1 and BCL2 inhibitors. Moreover, the combination of CA4948 and PU-H71 may be a candidate combination treatment in FLT3-mutated AML

Rationale for Combining the BCL2 Inhibitor Venetoclax with the PI3K Inhibitor Bimiralisib in the Treatment of IDH2- and FLT3-Mutated Acute Myeloid Leukemia.

In October 2020, the FDA granted regular approval to venetoclax (ABT-199) in combination with hypomethylating agents for newly-diagnosed acute myeloid leukemia (AML) in adults 75 years or older, or in patients with comorbidities precluding intensive chemotherapy. The treatment response to venetoclax combination treatment, however, may be short-lived, and leukemia relapse is the major cause of treatment failure. Multiple studies have confirmed the upregulation of the anti-apoptotic proteins of the B-cell lymphoma 2 (BCL2) family and the activation of intracellular signaling pathways associated with resistance to venetoclax. To improve treatment outcome, compounds targeting anti-apoptotic proteins and signaling pathways have been evaluated in combination with venetoclax. In this study, the BCL-XL inhibitor A1331852, MCL1-inhibitor S63845, dual PI3K-mTOR inhibitor bimiralisib (PQR309), BMI-1 inhibitor unesbulin (PTC596), MEK-inhibitor trametinib (GSK1120212), and STAT3 inhibitor C-188-9 were assessed as single agents and in combination with venetoclax, for their ability to induce apoptosis and cell death in leukemic cells grown in the absence or presence of bone marrow stroma. Enhanced cytotoxic effects were present in all combination treatments with venetoclax in AML cell lines and AML patient samples. Elevated in vitro efficacies were observed for the combination treatment of venetoclax with A1331852, S63845 and bimiralisib, with differing response markers for each combination. For the venetoclax and bimiralisib combination treatment, responders were enriched for IDH2 and FLT3 mutations, whereas non-responders were associated with PTPN11 mutations. The combination of PI3K/mTOR dual pathway inhibition with bimiralisib and BCL2 inhibition with venetoclax has emerged as a candidate treatment in IDH2- and FLT3-mutated AML

BeEAM High-Dose Chemotherapy with Polatuzumab (Pola-BeEAM) before ASCT in Patients with DLBCL-A Pilot Study.

(1) Introduction: BEAM is a high-dose chemotherapy (HDCT) frequently administered before autologous stem cell transplantation (ASCT) in diffuse large B-cell lymphoma (DLBCL). Bendamustine replacing BCNU (BeEAM) is similarly effective at lower toxicities. However, relapse remains the major cause of death in DLBCL. (2) Methods: This is a 12-patient pilot study of the BeEAM preparative regimen with additional polatuzumab vedotin (PV, targeting CD79b) aiming to establish feasibility and to reduce toxicity without increasing the early progression rate. PV was given once at the standard dose of 1.8 mg/kg at day -6 together with BeEAM-HDCT (days -7 to -1) before ASCT. (3) Results: 8/12 patients (67%) received PV with BeEAM as a consolidation of first-line treatment, and 4/12 patients (33%) received PV with BeEAM after relapse treatment. All patients experienced complete engraftment (neutrophils: median 11 days; platelets: 13 days). Gastrointestinal toxicities occurred in 7/12 patients (58%, grade 3). All patients developed neutropenic infections with at least one identified pathogen (bacterial: 10/12 patients; viral: 2/12; and fungal: 1/12). The complete remission rate by PET-CT 100 days post-ASCT was 92%, with one mortality due to early progression. Eleven out of twelve patients (92%) were alive without progression after a median follow-up of 15 months. (4) Conclusions: Our study with 12 patients suggests that combining PV with BeEAM HDCT is feasible and safe, but the limited cohort prevents definite conclusions regarding efficacy. Larger cohorts must be evaluated

Clonal Hematopoiesis after Autologous Stem Cell Transplantation Does Not Confer Adverse Prognosis in Patients with AML.

INTRODUCTION Despite a 50% cure rate, relapse remains the main cause of death in patients with acute myeloid leukemia (AML) consolidated with autologous stem cell transplantation (ASCT) in first remission (CR1). Clonal hematopoiesis of indeterminate potential (CH) increases the risk for hematological and cardiovascular disorders and death. The impact of CH persisting after ASCT in AML patients is unclear. MATERIALS AND METHODS We retrospectively investigated the prognostic value of persisting DNMT3A, TET2, or ASXL1 (DTA) mutations after ASCT. Patients underwent stratification depending on the presence of DTA mutations. RESULTS We investigated 110 consecutive AML patients receiving ASCT in CR1 after two induction cycles at our center between 2007 and 2020. CH-related mutations were present in 31 patients (28.2%) after ASCT. The baseline characteristics were similar between patients with or without persisting DTA mutations after ASCT. The median progression free survival was 26.9 months in patients without DTA mutations and 16.7 months in patients with DTA mutations (HR 0.75 (0.42-1.33), p = 0.287), and the median overall survival was 80.9 and 54.4 months (HR 0.79 (0.41-1.51), p = 0.440), respectively. CONCLUSION We suggest that DTA-CH after ASCT is not associated with an increased risk of relapse or death. The persistence of DTA mutations after induction should not prevent AML patients in CR1 from ASCT consolidation. Independent studies should confirm these data

sBCMA Plasma Level Dynamics and Anti-BCMA CAR-T-Cell Treatment in Relapsed Multiple Myeloma.

BACKGROUND Novel chimeric antigen receptor T-cells (CAR-T) target the B-cell maturation antigen (BCMA) expressed on multiple myeloma cells. Assays monitoring CAR-T cell expansion and treatment response are being implemented in clinical routine. METHODS Plasma levels of soluble BCMA (sBCMA) and anti-BCMA CAR-T cell copy numbers were monitored in the blood, following CAR-T cell infusion in patients with relapsed multiple myeloma. sBCMA peptide concentration was determined in the plasma, applying a human BCMA/TNFRS17 ELISA. ddPCR was performed using probes targeting the intracellular signaling domains 4-1BB und CD3zeta of the anti-BCMA CAR-T construct. RESULTS We report responses in the first five patients who received anti-BCMA CAR- T cell therapy at our center. Four patients achieved a complete remission (CR) in the bone marrow one month after CAR-T infusion, with three patients achieving stringent CR, determined by flow cytometry techniques. Anti-BCMA CAR-T cells were detectable in the peripheral blood for up to 300 days, with copy numbers peaking 7 to 14 days post-infusion. sBCMA plasma levels started declining one to ten days post infusion, reaching minimal levels 30 to 60 days post infusion, before rebounding to normal levels. CONCLUSIONS Our data confirm a favorable response to treatment in four of the first five patients receiving anti-BCMA CAR-T at our hospital. Anti-BCMA CAR-T cell expansion seems to peak in the peripheral blood in a similar pattern compared to the CAR-T cell products already approved for lymphoma treatment. sBCMA plasma level may be a valid biomarker in assessing response to BCMA-targeting therapies in myeloma patients

Outcome of Patients with Diffuse Large B-Cell Lymphoma Relapsing after Autologous Transplant before Availability of CAR-T Cell Treatment.

INTRODUCTION Autologous stem cell transplantation (ASCT) following high-dose chemotherapy is applied as salvage therapy in patients with relapsed disease or as first-line consolidation in high-risk DLBCL with chemo-sensitive disease. However, the prognosis of relapsing DLBCL post-ASCT remained poor until the availability of CAR-T cell treatment. To appreciate this development, understanding the outcome of these patients in the pre-CAR-T era is essential. METHODS We retrospectively analyzed 125 consecutive DLBCL patients who underwent HDCT/ASCT. RESULTS After a median follow-up of 26 months, OS and PFS were 65% and 55%. Fifty-three patients (42%) had a relapse (32 patients, 60%) or refractory disease (21 patients, 40%) after a median of 3 months post-ASCT. 81% of relapses occurred within the first year post-ASCT with an OS of 19% versus 40% at the last follow-up in patients with later relapses (p=0.0022). Patients with r/r disease after ASCT had inferior OS compared to patients in ongoing remission (23% versus 96%; p<0.0001). Patients relapsing post-ASCT without salvage therapy (n=22) had worse OS than patients with 1-4 subsequent treatment lines (n=31) (OS 0% versus 39%; median OS 3 versus 25 months; p<0.0001). Forty-one (77%) of patients relapsing after ASCT died, 35 of which due to progression. CONCLUSIONS Additional therapies can extend OS but mostly cannot prevent death in DLBCL relapsing/refractory post-ASCT. This study may serve as a reference to emerging results after CAR-T treatment in this population

Glofitamab Treatment in Relapsed or Refractory DLBCL after CAR T-Cell Therapy.

Chimeric antigen receptor T-cells (CAR T) treatment has become a standard option for patients with diffuse large B-cell lymphomas (DLBCL), which are refractory or relapse after two prior lines of therapy. However, little evidence exists for treatment recommendations in patients who relapse after CAR T-cell treatment and the outcome for such patients is poor. In this study, we evaluated the safety and efficacy of a monotherapy with the bispecific CD20xCD3 antibody glofitamab in patients who progressed after CAR T treatment. We report nine consecutive patients with progressive DLBCL after preceding CAR T-cell therapy. The patients received a maximum of 12 cycles of glofitamab after a single obinutuzumab pre-treatment at an academic institution. CRS was observed in two patients (grade 2 in both patients). We observed an overall response rate of 67%, with four patients achieving a complete response and a partial remission in two patients. Interestingly, we identified increased persistence of circulating CAR T-cells in peripheral blood in three of the five patients with measurable CAR T-cells. Our data suggest that glofitamab treatment is well tolerated and effective in patients with DLBCL relapsing after CAR T-cell therapy and can enhance residual CAR T-cell activity

BeEAM Conditioning including High-Dose Bendamustine before Autologous Stem Cell Transplantation Is Safe and Effective in Patients with Waldenstrom's Macroglobulinemia.

High-dose chemotherapy (HDCT) with autologous stem cell transplantation (ASCT) is an option to consolidate remission in Waldenstrom's macroglobulinemia (WM), particularly in selected younger patients with chemosensitive disease. BEAM, consisting of BCNU, etoposide, cytarabine, and melphalan, is often used as a conditioning regimen. However, problems with BCNU, including pneumotoxicity, tolerance, and availability, necessitate the search for alternatives. In this pilot study, we investigated high-dose chemotherapy with BeEAM, in which BCNU is replaced with high-dose bendamustine as an alternative conditioning regimen in six subsequent patients with WM. Bendamustine treatment was well tolerated without unexpected toxicities. The overall response rate was 6/6 patients (2 very good partial responses (VGPR) and 4 PR). After a median follow-up of 72 months, two (33%) patients relapsed. Median progression-free and overall survivals were not reached, and no severe late-onset toxicities were observed so far. In this pilot study, BeEAM conditioning before ASCT seems feasible, safe, and effective in patients with WM