Intensity Conditioning Allogeneic Hematopoietic Cell Research Articles

Maintenance Therapy with Venetoclax/Azacitidine Can be Safely Given after Venetoclax/FluBu2 RIC Allogeneic Transplantation for the Treatment of High Risk MDS/AML: Results of a Phase 1 Study

Background: Relapse is the main cause of transplant failure. We previously reported safety and durable remissions with venetoclax (Ven) added to fludarabine/busulfan (FluBu2) reduced intensity conditioning allogeneic hematopoietic cell transplantation (HCT) without planned maintenance therapy in patients (pts) with high risk myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML) (Garcia, Blood Advances, 2021). Detectable measurable residual disease (MRD) at day +100 frequently resulted in relapse after transplant. To address relapse risk after VenFluBu2 transplant in this high risk population, we assessed the safety and activity of Ven/Azacitidine (VenAza) maintenance therapy. Methods: In a Phase 1 trial (NCT03613532), pts with an 8/8 HLA-matched donor and diagnosis of AML with <5% blasts (ELN adverse, secondary, or flow MRD positive) or MDS/MPN or MDS with ≥10% blasts (secondary, IPSS higher risk, or TP53mut or RAS pathway mutations) received VenFluBu2 (Ven 400 mg on D-8 to D-2; fludarabine 30 mg/m2/d on D-5 to D-2; IV busulfan 0.8 mg/kg bid on D-5 to D-2), followed by PBSC infusion (D0) and tacrolimus/methotrexate GVHD prophylaxis. Between D42-D90, VenAza maintenance therapy (Ven 400 mg on D1-D14 and Aza 36 mg/m2 IV on D1-D5) was initiated in pts who engrafted and had no evidence of morphologic relapse or uncontrolled GVHD in 42-day (dose level 1) or 28-day (dose level 2) cycles for up to 1 year. DLT was defined as Gr 4 neutropenia/thrombocytopenia >2 wks. Clinical NGS (sensitivity 1-3%) was performed before and after HCT (+28, +100). BH3 profiling analysis was performed on 11 paired blood samples before/after cycle 1 of VenAza. Results: As of 6/2022, 27 pts were enrolled and had the following disease status at time of HCT: 10 AML pts (8 CR, 2 CRi); 16 MDS pts (1 CR, 5 marrow CR (mCR) with hematologic improvement (HI), 5 mCR without HI, 1 HI-erythroid alone, and 4 active disease (5-10% blasts)); and 1 MDS/MPN pt in CR. Pts had a median age of 67y (range 47,78), co-morbidities (52% HCT-CI≥4), 44% were flow MRD negative, and 56% had Ven exposure prior to HCT. Baseline TP53mut was present in 59% (16/27). After VenFluBu2 RIC HCT, 22 of 27 pts received VenAza maintenance therapy (n=11 per dose level); remaining 5 of 27 pts did not (3 relapsed early, 2 withdrew). No DLTs were observed. The most common grade 3-4 treatment emergent adverse events (AE) during maintenance were anemia (45%), neutropenia (95%) and thrombocytopenia (91%), which were mainly transient. Cycle 1 nadir occurred on D29 for ANC (median 1.2 K/µL, range 0,3.7) and on D15 for platelet (median 119 K/µL, range 70,169). Infection during maintenance was reported in only 1 pt (n=1 BK viruria). Serious AEs were reported in 2 (1 rash; 1 BK case). Median of 4 VenAza cycles were received in DL1 (range 1,8); DL2 on-going. Cumulative incidence of grade ≥2 acute GVHD at 6 mo was 22% (95% CI: 9,39) and chronic GVHD at 1y was 23% (95% CI: 8,42). With a median 12 mo follow up (range 4-21), regardless of maintenance status, 1y OS, PFS, NRM and relapse were 70% (95% CI: 46,85), 57% (95% CI: 36,74), 0% and 43% (95% CI: 28,57), respectively. To date, 12 of 27 pts have relapsed (4 before, 7 during, and 1 after maintenance on D523). Ven use prior to HCT did not impact outcome. Pre-transplant flow MRD negativity was associated with improved 1y OS (88% vs 50%, p=0.03) and 1y PFS (81% vs 39%, p=0.08). Flow MRD was positive in 17% (4/24) at D28 and in 44% (11/25) at D100. At time of HCT, NGS was positive in 89% (24/27), but this reduced to 42% (10/24) at D28 and 58% (14/24) at D100 (Figure 1). PFS was similar for those with or without TP53mut at HCT (p=0.14). Among 22 pts that received VenAza maintenance therapy, 1y PFS and 1y OS were 65% (95% CI: 40,82) and 79% (95% CI: 52,92), respectively. BH3 profiling did not reveal any significant changes in baseline apoptotic priming in CD3+, CD3+CD4+, CD3+CD8+ T cells, and CD3+CD4+CD127-CD25+ Treg cells, suggesting VenAza was not cytotoxic to T cells. Flow cytometry to assess for immune recovery is in process. Conclusions: VenAza maintenance therapy after VenFluBu2 RIC alloHCT appears to be safe with low infection rate and no excessive GVHD. This Ven-based peri-transplant strategy for high risk MDS/AML pts has encouraging activity though relapses still occurred. A cohort assessing all oral maintenance (Ven plus decitabine/cedazuridine) is enrolling. A randomized trial will be required to evaluate the benefit of Ven with conditioning chemotherapy or with maintenance therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Reduced intensity conditioning allogeneic hematopoietic cell transplantation for adult acute myeloid leukemia in complete remission - a review from the Acute Leukemia Working Party of the EBMT.

Acute myeloid leukemia is the most common indication for an allogeneic hematopoietic cell transplant. The introduction of reduced intensity conditioning has expanded the recipient pool for transplantation, which has importantly made transplant an option for the more commonly affected older age groups. Reduced intensity conditioning allogeneic transplantation is currently the standard of care for patients with intermediate or high-risk acute myeloid leukemia and is now most often employed in older patients and those with medical comorbidities. Despite being curative for a significant proportion of patients, post-transplant relapse remains a challenge in the reduced intensity conditioning setting. Herein we discuss the studies that demonstrate the feasibility of reduced intensity conditioning allogeneic transplants, compare the outcomes of reduced intensity conditioning versus chemotherapy and conventional myeloablative conditioning regimens, describe the optimal donor and stem cell source, and consider the impact of post-remission consolidation, comorbidities, center experience, and more intensive (reduced toxicity conditioning) regimens on outcomes. Additionally, we discuss the need for further prospective studies to optimize transplant outcomes.

Lowering the alemtuzumab dose in reduced intensity conditioning allogeneic hematopoietic cell transplantation is associated with a favorable early intense natural killer cell recovery

Background aimsThe anti-CD52 monoclonal antibody alemtuzumab is employed in allogeneic hematopoietic cell transplantation (alloHCT) for the prevention of graft-versus-host disease (GVHD). However, its optimal dosing in this setting has not been determined yet. We compared three different alemtuzumab dose levels in reduced intensity conditioning (RIC) alloHCT with respect to lymphocyte recovery and outcome. MethodsIn 127 consecutive patients with predominantly advanced stage hematologic malignancies, a first alloHCT after RIC was performed, applying a fludarabine-based protocol (in 93% FBM: fludarabine, bis-chloroethyl-nitrosourea [BCNU], and melphalan). For GVHD prophylaxis, cyclosporine and alemtuzumab at three different dose levels (40 mg, 20 mg, 10 mg) were administered. Recovery of the peripheral blood (PB) lymphocyte sub-populations and clinical outcome were determined with regard to the alemtuzumab dose. ResultsNatural killer (NK) cell concentrations in PB around day +30 correlated inversely with the alemtuzumab dose, whereas other PB lymphocyte subtypes remained essentially unaffected by dosing of alemtuzumab. Lower alemtuzumab doses were associated with a tendency toward improved overall survival mainly during the early post-transplantation months. With regard to the PB NK cell concentration around day +30, “early intense NK cell reconstituters” tended to show an overall survival benefit. ConclusionsAn alemtuzumab dose reduction to only 10–20 mg provides sufficient GVHD prophylaxis and supports improved NK cell regeneration early after alloHCT in PB (“NK cell saving effect”), which may have a positive effect on overall survival.

Post Transplant Allogeneic Antibody Responses Form against Annexin 8

Allogeneic hematopoietic cell transplantation can cure hematologic malignancies through graft versus leukemia effects but are limited by graft versus host disease. Antibodies against human Y chromosome antigens are associated with graft versus host disease and we hypothesized that antibodies could conversely be associated with post transplant graft versus leukemia effects. We identified an index male patient with chronic lymphocytic leukemia who received a female PBSC graft following reduced intensity conditioning allogeneic hematopoietic cell transplantation. This F→M had developed allogeneic antibodies against H-Y antigen UTY. We hypothesized allogeneic antibodies develop against autosomal minor histocompatibility antigens and could be identified as targets of allo-antibodies. Protein microarrays (Invitrogen Protoarray) featuring 8000 baculovirus expressed human proteins with N-terminal GST fusions were screened with plasma samples from the index patient and antibodies binding to potential graft versus leukemia antigens were detected with fluorescently tagged secondary antibodies. We compared post-transplant with pre-transplant and donor plasma fluorescent intensities and identified new post transplant antibody responses against annexin 8 which were not present prior to transplant or in the donor. Our finding of new antibody responses against annexin 8 was confirmed by Western blot against E.coli expressed affinity purified recombinant V5-His6 tagged annexin 8.Annexin 8 is a membrane associated protein postulated to play a role in cellular proliferation. Recent genomic analyses have identified three loci coding for three separate annexin 8 genes clustered on chromosome 10 in a region of high frequency copy number variation (CNV). In addition, the annexin 8 mRNA transcript undergoes alternative splicing with one variant being identified from a choriocarcinoma cell line. Both CNV and alternative splicing may result in immunologic disparities between donor and recipient inducing alloimmunity.. Therefore, we tested these possibilities by synthesizing recombinant V5-His6 annexin 8 proteins corresponding to the three possible isoforms and using them in an ELISA to screen 187 patients with a variety of malignancies for post-allogeneic transplant antibodies. The recombinant proteins included the alternative splice variant from choriocarcinoma which differed from the common variant by the insertion of a 38 amino acid sequence after the second exon and the deletion of two 57 and 32 amino acid sequences from exons 6, 7, and 10 of the common variant, as well as two versions of the common variant which differed by a G to C nonsynonymous single nucleotide polymorphism resulting in a change from glycine to alanine. These two recombinant common variant isoforms correspond to the reported sequences of two of the annexin 8 loci affected by copy number variation. Thus reactions to either, but not both, might indicate disparities in annexin 8 copy number between recipient and donor. Of 187 patients, 22 had significant antibody reactions (defined as greater than 1 standard deviation above the mean in normal controls) to either of the common variant isoforms but only 4 had reactions to both isoforms suggesting that antibodies were differentially recognizing annexin 8 isoforms based on a single nonsynonymous single nucleotide polymorphism. Six of 187 patients had significant antibody reactions against the splice variant isoform alone, suggesting that the alternatively inserted exon may be the antibody target.Taken together, our findings suggest that annexin 8 may be a target of the post-transplant humoral response due to immune disparities between recipient and donor caused by copy number variation as well as alternative splicing.