GPAM mediated lysophosphatidic acid synthesis regulates mitochondrial dynamics in acute myeloid leukemia.

Metabolic alterations, especially in the mitochondria, play important roles in several kinds of cancers, including acute myeloid leukemia (AML). However, AML-specific molecular mechanisms that regulate mitochondrial dynamics remain elusive. Through the metabolite screening comparing CD34+ AML cells and healthy hematopoietic stem/progenitor cells, we identified enhanced lysophosphatidic acid (LPA) synthesis activity in AML. LPA is synthesized from glycerol-3-phosphate by glycerol-3-phosphate acyltransferases (GPATs), rate-limiting enzymes of the LPA synthesis pathway. Among the four isozymes of GPATs, glycerol-3-phosphate acyltransferases, mitochondrial (GPAM) was highly expressed in AML cells, and the inhibition of LPA synthesis by silencing GPAM or FSG67 (a GPAM-inhibitor) significantly impaired AML propagation through the induction of mitochondrial fission, resulting in the suppression of oxidative phosphorylation and the elevation of reactive oxygen species. Notably, inhibition of this metabolic synthesis pathway by FSG67 administration did not affect normal human hematopoiesis in vivo. Therefore, the GPAM-mediated LPA synthesis pathway from G3P represents a critical metabolic mechanism that specifically regulates mitochondrial dynamics in human AML, and GPAM is a promising potential therapeutic target.

Procalcitonin elevation in febrile recipients during pre-transplant conditioning with anti-thymocyte globulin.

Infection is a major contributor to non-relapse mortality in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Detecting infectious diseases in febrile patients during pretransplant conditioning is crucial for subsequent transplant success. Procalcitonin (PCT) is an auxiliary diagnostic marker of severe bacterial infections and has been proposed as a useful predictor of infection in patients undergoing allo-HSCT. Pre-transplant use of anti-thymocyte globulin (ATG) can cause side effects, such as fever and hypotension, which must be distinguished from infectious diseases. Although ATG administration may increase PCT levels, data on PCT levels in febrile patients after ATG administration are limited. Furthermore, no studies have compared PCT levels during allo-HSCT conditioning using ATG or non-ATG regimens. To investigate whether ATG increases PCT levels during febrile episodes in pre-transplant conditioning and whether PCT could be used to discriminate infections during this period, we analyzed 17 ATG and 59 non-ATG patients with fever and who underwent PCT level measurements during pre-transplant conditioning. Our findings revealed that ATG administration was the only significant factor that increased PCT positivity during fever (p = 0.01). In contrast, infectious diseases did not affect PCT positivity in the ATG group (p = 0.24). Furthermore, bloodstream infection was a significant risk factor for PCT positivity in patients who received non-ATG regimens (p < 0.01). Incorporating PCT levels into the diagnostic workup for infectious diseases requires careful consideration, particularly for patients receiving ATG regimens.

Human acute leukemia uses branched-chain amino acid catabolism to maintain stemness through regulating PRC2 function.

Cancer-specific metabolic activities play a crucial role in the pathogenesis of human malignancies. To investigate human acute leukemia-specific metabolic properties, we comprehensively measured the cellular metabolites within the CD34+ fraction of normal hematopoietic stem progenitor cells (HSPCs), primary human acute myelogenous leukemia (AML), and acute lymphoblastic leukemia (ALL) cells. Here, we show that human leukemia cells are addicted to the branched-chain amino acid (BCAA) metabolism to maintain their stemness, irrespective of myeloid or lymphoid types. Human primary acute leukemias had BCAA transporters for BCAA uptake, cellular BCAA, α-ketoglutarate (α-KG), and cytoplasmic BCAA transaminase-1 (BCAT1) at significantly higher levels than control HSPCs. Isotope-tracing experiments showed that in primary leukemia cells, BCAT1 actively catabolizes BCAA using α-KG into branched-chain α-ketoacids, whose metabolic processes provide leukemia cells with critical substrates for the trichloroacetic acid cycle and the synthesis of nonessential amino acids, both of which reproduce α-KG to maintain its cellular level. In xenogeneic transplantation experiments, deprivation of BCAA from daily diet strongly inhibited expansion, engraftment and self-renewal of human acute leukemia cells. Inhibition of BCAA catabolism in primary AML or ALL cells specifically inactivates the function of the polycomb repressive complex 2, an epigenetic regulator for stem cell signatures, by inhibiting the transcription of PRC components, such as zeste homolog 2 and embryonic ectoderm development. Accordingly, BCAA catabolism plays an important role in the maintenance of stemness in primary human AML and ALL, and molecules related to the BCAA metabolism pathway should be critical targets for acute leukemia treatment.

Successful pseudo-autologous stem cell transplantation for donor-derived Burkitt lymphoma occurring 9 years after allogeneic transplantation.

Donor-derived hematological malignancies have been recognized as rare but serious late complications in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Most cases in the literature were diagnosed as myelodysplastic syndrome or acute leukemia, with very few malignant lymphoma reported. We herein present another case of donor-derived Burkitt lymphoma that occurred 9 years after allo-HSCT under continued administration of immunosuppressants for chronic graft-versus-host disease (GVHD). The patient achieved a partial response after rituximab-combined intensive chemotherapy. To reduce the risk of relapse and to avoid organ toxicities due to repeated chemotherapies, we performed upfront high-dose chemotherapy followed by stem cell rescue using donor-derived CD34+ cells, called pseudo-autologous HSCT (pASCT), and adjusted immunosuppressants appropriately. The patient remained disease-free for 23 months after pASCT without exacerbation of cGVHD. Although the observation period has been relatively short and longer follow-up is needed, pASCT may be a feasible option for donor-derived lymphoma even in patients with active cGVHD.

Anti-GPRC5D/CD3 Bispecific T-Cell-Redirecting Antibody for the Treatment of Multiple Myeloma.

Although treatment advances over recent decades have significantly improved survival of patients with multiple myeloma, there is still an unmet medical need for more effective treatments. In this study, we identified G-protein-coupled receptor family C group 5 member D (GPRC5D) expression on the surface of malignant cells involved in multiple myeloma, but except for plasma cells and B cells, not at appreciable levels on normal hematopoietic cells and bone marrow progenitors, including hematopoietic stem cells. In addition, we constructed IgG-based anti-GPRC5D/CD3 bispecific T-cell-redirecting antibodies (GPRC5D TRAB), which suppressed the tumor growth of GPRC5D-positive myeloma cells through the activation of T cells in vitro and in vivo in xenograft models. Collectively, these findings suggest that GPRC5D is an antigen specific to multiple myeloma and a potential target of TRAB therapy.

Expansion of NKG2C-expressing Natural Killer Cells after Umbilical Cord Blood Transplantation in a Patient with Peripheral T-cell Lymphoma with Cytotoxic Molecules.

A 64-year-old woman presented with generalized lymphadenopathy and systemic manifestations. The examination of a biopsy specimen revealed peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) expressing cytotoxic molecules. Umbilical cord blood transplantation was successful during a partial remission state after the administration of salvage chemotherapy. The donor-derived large granular lymphocytes started to increase as a result of cytomegalovirus reactivation. The fraction of natural killer (NK) cells expressing the NKG2C molecule accounted for one-third of the total lymphocytes for almost two years. We implicitly indicate the association between the persistence of donor-derived NKG2C+ NK cell-expansion and maintaining a complete remission in similar cases of aggressive PTCL-NOS.

High throughput imaging cytometer with acoustic focussing.

We demonstrate an imaging flow cytometer that uses acoustic levitation to assemble cells and other particles into a sheet structure. This technique enables a high resolution, low noise CMOS camera to capture images of thousands of cells with each frame. While ultrasonic focussing has previously been demonstrated for 1D cytometry systems, extending the technology to a planar, much higher throughput format and integrating imaging is non-trivial, and represents a significant jump forward in capability, leading to diagnostic possibilities not achievable with current systems. A galvo mirror is used to track the images of the moving cells permitting exposure times of 10 ms at frame rates of 50 fps with motion blur of only a few pixels. At 80 fps, we demonstrate a throughput of 208 000 beads per second. We investigate the factors affecting motion blur and throughput, and demonstrate the system with fluorescent beads, leukaemia cells and a chondrocyte cell line. Cells require more time to reach the acoustic focus than beads, resulting in lower throughputs; however a longer device would remove this constraint.