Prophylactic maintenance with venetoclax/azacitidine after reduced-intensity conditioning allogeneic transplant for high-risk MDS and AML.

ABSTRACT: We conducted a phase 1 trial assessing safety and efficacy of prophylactic maintenance therapy with venetoclax and azacitidine (Ven/Aza) for patients with high-risk myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML) undergoing reduced intensity allogeneic stem cell transplantation (allo-SCT) after Ven and fludarabine/busulfan conditioning (Ven/FluBu2 allo-SCT) with tacrolimus and methotrexate as graft-versus-host disease (GVHD) prophylaxis. Among 27 patients who underwent Ven/FluBu2 allo-SCT (55.6% with prior Ven exposure, and 96% with positive molecular measurable residual disease), 22 received maintenance therapy with Aza 36 mg/m2 intravenously on days 1 to 5, and Ven 400 mg by mouth on days 1 to 14 per assigned dose schedule/level (42-day cycles × 8, or 28-day cycles × 12). During maintenance, the most common grade 3-4 adverse events were leukopenia, neutropenia, and thrombocytopenia, which were transient and manageable. Infections were uncommon (n = 4, all grade 1-2). The 1-year and 2-year moderate/severe chronic GVHD rates were 4% (95% confidence interval [CI], 0.3%-18%) and 22% (95% CI, 9%-40%), respectively. After a median follow-up of 25 months among survivors, the median overall survival (OS) was not reached. Among the 22 patients who received Ven/Aza maintenance, the 2-year OS, progression-free survival, nonrelapse mortality, and cumulative incidence of relapse rates were 67% (95% CI, 43%-83%), 59% (95% CI, 36%-76%), 0%, and 41% (95% CI, 20%-61%), respectively. Immune monitoring demonstrated no significant impact on T-cell expansion but identified reduced B-cell expansion compared with controls. This study demonstrates prophylactic Ven/Aza maintenance can be safely administered for patients with high-risk MDS/AML, but a randomized study is required to properly assess any potential benefit. This trial was registered at www.clinicaltrials.gov as #NCT03613532.

Multicenter Phase I Trial of Ivosidenib as Maintenance Treatment Following Allogeneic Hematopoietic Cell Transplantation for IDH1-Mutated Acute Myeloid Leukemia.

PURPOSE: Isocitrate dehydrogenase 1 (IDH1) mutations occur in 5% to 10% of patients with acute myeloid leukemia (AML). Ivosidenib is an IDH1 inhibitor, approved for use in patients with IDH1-mutated AML. PATIENTS AND METHODS: We conducted a multicenter, phase I trial of maintenance ivosidenib following allogeneic hematopoietic cell transplantation (HCT) in patients with IDH1-mutated AML. Ivosidenib was initiated between days 30 and 90 following HCT and continued for up to 12 28-day cycles. The first dose level was 500 mg daily, with level reduction to 250 mg daily, if needed, in a 3 × 3 de-escalation design. Ten additional patients would then receive the MTD or recommended phase 2 dose (RP2D). The primary endpoint was establishing the MTD or RP2D of ivosidenib. RESULTS: Eighteen patients were enrolled, of whom 16 initiated post-HCT ivosidenib. One dose-limiting toxicity, grade(g) 3 QTc prolongation, was observed. The RP2D was established at 500 mg daily. Attributable g≥3 adverse events were uncommon, with the most common being QTc prolongation in 2 patients. Eight patients discontinued maintenance, with only one due to adverse event. Six-month cumulative incidence (CI) of gII-IV aGVHD was 6.3%, and 2-year CI of all cGVHD was 63%. Two-year CI of relapse and nonrelapse mortality (NRM) were 19% and 0%, respectively. Two-year progression-free (PFS) was 81%, and 2-year overall survival (OS) was 88%. CONCLUSIONS: Ivosidenib is safe and well-tolerated as maintenance therapy following HCT. Cumulative incidence of relapse and NRM, as well as estimations of PFS and OS, were promising in this phase I study.

Enasidenib as maintenance following allogeneic hematopoietic cell transplantation for IDH2-mutated myeloid malignancies.

IDH2 (isocitrate dehydrogenase 2) mutations occur in approximately 15% of patients with acute myeloid leukemia (AML). The IDH2 inhibitor enasidenib was recently approved for IDH2-mutated relapsed or refractory AML. We conducted a multi-center, phase I trial of maintenance enasidenib following allogeneic hematopoietic cell transplantation (HCT) in patients with IDH2-mutated myeloid malignancies. Two dose levels, 50mg and 100mg daily were studied in a 3 × 3 dose-escalation design, with 10 additional patients treated at the recommended phase 2 dose (RP2D). Enasidenib was initiated between days 30 and 90 following HCT and continued for twelve 28-day cycles. Twenty-three patients were enrolled, of whom 19 initiated post-HCT maintenance. Two had myelodysplastic syndrome, and 17 had AML. All but 3 were in first complete remission. No dose limiting toxicities were observed, and the RP2D was established at 100mg daily. Attributable grade ≥3 toxicities were rare, with the most common being cytopenias. Eight patients stopped maintenance before completing 12 cycles, due to adverse events (n=3), pursuing treatment for graft-vs-host disease (GVHD) (n=2), clinician choice (n=1), relapse (n=1), and COVID infection (n=1). No cases of grade ≥3 acute GVHD were seen, and 12-month cumulative incidence of moderate/severe chronic GVHD was 42% (20-63%). Cumulative incidence of relapse was 16% (95% CI: 3.7-36%); 1 subject relapsed while receiving maintenance. Two-year progression-free and overall survival were 69% (95% CI: 39-86%) and 74% (95% CI, 44-90%), respectively. Enasidenib is safe, well-tolerated, with preliminary activity as maintenance therapy following HCT, and merits additional study. The study was registered at www.clinicaltrials.gov (#NCT03515512).

GM-CSF secreting leukemia cell vaccination for MDS/AML after allogeneic HSCT: a randomized, double-blinded, phase 2 trial.

Vaccination using irradiated, adenovirus transduced autologous myeloblasts to secrete granulocyte-macrophage colony-stimulating factor (GVAX) early after allogeneic hematopoietic stem cell transplantation (HSCT) can induce potent immune responses. We conducted a randomized phase 2 trial of GVAX after HSCT for myelodysplastic syndrome with excess blasts or relapsed/refractory acute myeloid leukemia. Myeloblasts were harvested before HSCT to generate the vaccine. Randomization to GVAX vs placebo (1:1) was stratified according to disease, transplant center, and conditioning. Graft-versus-host disease (GVHD) prophylaxis included tacrolimus and methotrexate. GVAX or placebo vaccination was started between day 30 and 45 if there was engraftment and no GVHD. Vaccines were administered subcutaneously/intradermally weekly × 3, then every 2 weeks × 3. Tacrolimus taper began after vaccine completion. A total of 123 patients were enrolled, 92 proceeded to HSCT, and 57 (GVAX, n = 30; placebo, n = 27) received at least 1 vaccination. No Common Toxicity Criteria grade 3 or worse vaccine-related adverse events were reported, but injection site reactions were more common after GVAX (10 vs 1; P = .006). With a median follow-up of 39 months (range, 9-89 months), 18-month progression-free survival, overall survival, and relapse incidence were 53% vs 55% (P = .79), 63% vs 59% (P = .86), and 30% vs 37% (P = .51) for GVAX and placebo, respectively. Nonrelapse mortality at 18 months was 17% vs 7.7% (P = .18), grade II to IV acute GVHD at 12 months was 34% vs 12% (P = .13), and chronic GVHD at 3 years was 49% vs 57% for GVAX and placebo (P = .26). Reconstitution of T, B, and natural killer cells was not decreased or enhanced by GVAX. There were no differences in serum major histocompatibility chain-related protein A/B or other immune biomarkers between GVAX and placebo. GVAX does not improve survival after HSCT for myelodysplastic syndrome/acute myeloid leukemia. This trial was registered at www.clinicaltrials.gov as #NCT01773395.

Adding venetoclax to fludarabine/busulfan RIC transplant for high-risk MDS and AML is feasible, safe, and active.

Adding the selective BCL-2 inhibitor venetoclax to reduced-intensity conditioning chemotherapy (fludarabine and busulfan [FluBu2]) may enhance antileukemic cytotoxicity and thereby reduce the risk of posttransplant relapse. This phase 1 study investigated the recommended phase 2 dose (RP2D) of venetoclax, a BCL-2 selective inhibitor, when added to FluBu2 in adult patients with high-risk acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and MDS/myeloproliferative neoplasms (MPN) undergoing transplant. Patients received dose-escalated venetoclax (200-400 mg daily starting day -8 for 6-7 doses) in combination with fludarabine 30 mg/m2 per day for 4 doses and busulfan 0.8 mg/kg twice daily for 8 doses on day -5 to day -2 (FluBu2). Transplant related-toxicity was evaluated from the first venetoclax dose on day -8 to day 28. Twenty-two patients were treated. At study entry, 5 patients with MDS and MDS/MPN had 5% to 10% marrow blasts, and 18 (82%) of 22 had a persistent detectable mutation. Grade 3 adverse events included mucositis, diarrhea, and liver transaminitis (n = 3 each). Neutrophil/platelet recovery and acute/chronic graft-versus-host-disease rates were similar to those of standard FluBu2. No dose-limiting toxicities were observed. The RP2D of venetoclax was 400 mg daily for 7 doses. With a median follow-up of 14.7 months (range, 8.6-24.8 months), median overall survival was not reached, and progression-free survival was 12.2 months (95% confidence interval, 6.0-not estimable). In patients with high-risk AML, MDS, and MDS/MPN, adding venetoclax to FluBu2 was feasible and safe. To further address relapse risk, assessment of maintenance therapy after venetoclax plus FluBu2 transplant is ongoing. This study was registered at clinicaltrials.gov as #NCT03613532.

Supporting Biomedical Research Training for Historically Underrepresented Undergraduates Using Interprofessional, Nonformal Education Structures.

Research experience provides critical training for new biomedical research scientists. Students from underrepresented populations studying science, technology, engineering, and mathematics (STEM) are increasingly recruited into research pathways to diversify STEM fields. However, support structures outside of research settings designed to help these students navigate biomedical research pathways are not always available; nor are program support components outside the context of laboratory technical skills training and formal mentorship well understood. This study leveraged a multi-institutional research training program, Enhancing Cross-Disciplinary Infrastructure and Training at Oregon (EXITO), to explore how nine institutions designed a new curricular structure (Enrichment) to meet a common goal of enhancing undergraduate research training and student success. EXITO undergraduates participated in a comprehensive, 3-year research training program with the Enrichment component offered across nine sites: three universities and six community colleges, highly diverse in size, demographics, and location. Sites' approaches to supporting students in the training program were studied over a 30-month period. All sites independently created their own nonformal curricular structures, implemented interprofessionally via facilitated peer groups. Site data describing design and implementation were thematically coded to identify essential programmatic components across sites, with student feedback used to triangulate findings. Enrichment offered students time to critically reflect on their interests, experiences, and identities in research; network with peers and professionals; and support negotiation of hidden and implicit curricula. Students reported the low-pressure setting and student-centered curriculum balanced the high demands associated with academics and research. Core curricular themes described Enrichment as fostering a sense of community among students, exposing students to career paths and skills, and supporting development of students' professional identities. The non-formal, interprofessional curricula enabled students to model diverse biomedical identities and pathways for each other while informing institutional structures to improve diverse undergraduate students' success in academia and research.

Stiffness of out-of-plane-motion stages with large-motion folded fractal flexible hinges.

This paper introduces a new planar flexible hinge of fractal configuration to be incorporated in out-of-plane-motion compliant stages that cover a wide stiffness range. The large-displacement fractal hinge consists of a series of scaled-down, concentric, circular-axis flexible segments that are connected in a folded manner by radial rigid links. In-plane and out-of-plane compliance matrices are derived for fractal hinges with variable planar geometry features. The flexible hinges are assembled in a radial architecture to form compliant stages that can be utilized for piston-type, out-of-plane sensing or actuation. The analytical model calculates the stage active, out-of-plane stiffness, as well as its parasitic, in-plane stiffness. The stage analytical stiffness is confirmed by the experimental testing of a prototype and by finite element simulation. Furthermore, analytical-model simulation is performed to evaluate the variations in the active and parasitic stiffnesses with key geometric parameters, which also enables optimization.

A Practical Guide to Using CV Analysis for Determining the Locus of Synaptic Plasticity.

Long-term synaptic plasticity is widely believed to underlie learning and memory in the brain. Whether plasticity is primarily expressed pre- or postsynaptically has been the subject of considerable debate for many decades. More recently, it is generally agreed that the locus of plasticity depends on a number of factors, such as developmental stage, induction protocol, and synapse type. Since presynaptic expression alters not just the gain but also the short-term dynamics of a synapse, whereas postsynaptic expression only modifies the gain, the locus has fundamental implications for circuits dynamics and computations in the brain. It therefore remains crucial for our understanding of neuronal circuits to know the locus of expression of long-term plasticity. One classical method for elucidating whether plasticity is pre- or postsynaptically expressed is based on analysis of the coefficient of variation (CV), which serves as a measure of noise levels of synaptic neurotransmission. Here, we provide a practical guide to using CV analysis for the purposes of exploring the locus of expression of long-term plasticity, primarily aimed at beginners in the field. We provide relatively simple intuitive background to an otherwise theoretically complex approach as well as simple mathematical derivations for key parametric relationships. We list important pitfalls of the method, accompanied by accessible computer simulations to better illustrate the problems (downloadable from GitHub), and we provide straightforward solutions for these issues.

Unconventional NMDA Receptor Signaling.

In the classical view, NMDA receptors (NMDARs) are stably expressed at the postsynaptic membrane, where they act via Ca2+ to signal coincidence detection in Hebbian plasticity. More recently, it has been established that NMDAR-mediated transmission can be dynamically regulated by neural activity. In addition, NMDARs have been found presynaptically, where they cannot act as conventional coincidence detectors. Unexpectedly, NMDARs have also been shown to signal metabotropically, without the need for Ca2+ This review highlights novel findings concerning these unconventional modes of NMDAR action.

Differential Regulation of Evoked and Spontaneous Release by Presynaptic NMDA Receptors.

Presynaptic NMDA receptors (preNMDARs) control synaptic release, but it is not well understood how. Rab3-interacting molecules (RIMs) provide scaffolding at presynaptic active zones and are involved in vesicle priming. Moreover, c-Jun N-terminal kinase (JNK) has been implicated in regulation of spontaneous release. We demonstrate that, at connected layer 5 pyramidal cell pairs of developing mouse visual cortex, Mg2+-sensitive preNMDAR signaling upregulates replenishment of the readily releasable vesicle pool during high-frequency firing. In conditional RIM1αß deletion mice, preNMDAR upregulation of vesicle replenishment was abolished, yet preNMDAR control of spontaneous release was unaffected. Conversely, JNK2 blockade prevented Mg2+-insensitive preNMDAR signaling from regulating spontaneous release, but preNMDAR control of evoked release remained intact. We thus discovered that preNMDARs signal differentially to control evoked and spontaneous release by independent and non-overlapping mechanisms. Our findings suggest that preNMDARs may sometimes signal metabotropically and support the emerging principle that evoked and spontaneous release are distinct processes. VIDEO ABSTRACT.

A generalized analytical compliance model for transversely symmetric three-segment flexure hinges.

This paper presents a generalized compliance model for a three-segment notch flexure hinge with transverse symmetry. This flexure hinge configuration is most frequently employed in planar-motion, small-displacement compliant mechanisms. The axial and bending compliances are derived for this flexure hinge based on the compliances of two flexure components. The derivation is generalized such that it can be applied to various segment geometries. Using this open-ended model, a three-segment right elliptical corner-filleted flexure hinge design was analyzed. This geometric configuration introduces additional geometric parameters, which can be used to optimize the compliance of the flexure hinge without modifying its gross dimensions. The results of the analysis were validated in part by modifying the geometric parameters of the center segment and elliptical corner fillets to form limiting cases corresponding to several previously investigated configurations, namely right elliptical, three-segment right circular corner-filleted, and right circular geometries. Finite element analysis simulation and experimental testing were used to further validate the three-segment right elliptical corner-filleted analytical model. Additional simulations based on the analytical model were performed to highlight the influence of geometric parameters on compliances and to investigate shear effects for short flexure hinges.