Low-dose decitabine plus venetoclax as post-transplant maintenance for high-risk myeloid malignancies.

Relapse remains a major cause of treatment failure following allogeneic stem cell transplantation (allo-SCT) for patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We retrospectively investigated low-dose decitabine and venetoclax (DEC/VEN) as post-transplant maintenance in 26 older patients with AML and MDS. The cumulative incidence of day 100 gIII-IV acute graft versus host disease (GVHD) and 1-year moderate-severe chronic GVHD was 5% and 26%, respectively. One patient relapsed 14 m after transplant. The 1-year non-relapse mortality and survival were 11% and 84%, respectively. DEC/VEN is a safe and potentially effective strategy to reduce the risk of post-transplant relapse.

NCCN Guidelines® Insights: Hematopoietic Cell Transplantation, Version 3.2022.

The NCCN Guidelines for Hematopoietic Cell Transplantation (HCT) provide an evidence- and consensus-based approach for the use of autologous and allogeneic HCT in the management of malignant diseases in adult patients. HCT is a potentially curative treatment option for patients with certain types of malignancies; however, recurrent malignancy and transplant-related complications often limit the long-term survival of HCT recipients. The purpose of these guidelines is to provide guidance regarding aspects of HCT, including pretransplant recipient evaluation, hematopoietic cell mobilization, and treatment of graft-versus-host disease-a major complication of allogeneic HCT-to enable the patient and clinician to assess management options in the context of an individual patient's condition. These NCCN Guidelines Insights provide a summary of the important recent updates to the NCCN Guidelines for HCT, including the incorporation of a newly developed section on the Principles of Conditioning for HCT.

Axatilimab for Chronic Graft-Versus-Host Disease After Failure of at Least Two Prior Systemic Therapies: Results of a Phase I/II Study.

PURPOSE: Chronic graft-versus-host disease (cGVHD) remains the major cause of late morbidity after allogeneic hematopoietic cell transplantation. Colony-stimulating factor 1 receptor (CSF-1R)-dependent macrophages promote cGVHD fibrosis, and their elimination in preclinical studies ameliorated cGVHD. Axatilimab is a humanized monoclonal antibody that inhibits CSF-1R signaling and restrains macrophage development. PATIENTS AND METHODS: This phase I (phI)/phase II (phII) open-label study (ClinicalTrials.gov identifier: NCT03604692) evaluated safety, tolerability, and efficacy of axatilimab in patients age ≥ 6 years with active cGVHD after ≥ 2 prior systemic therapy lines. Primary objectives in phI were to identify the optimal biologic and recommended phII dose and in phII to evaluate the overall (complete and partial) response rate (ORR) at the start of treatment cycle 7. RESULTS: Forty enrolled patients (17 phI; 23 phII) received at least one axatilimab dose. In phI, a dose of 3 mg/kg given once every 4 weeks met the optimal biologic dose definition. Two dose-limiting toxicities occurred at the 3 mg/kg dose given once every 2 weeks. At least one treatment-related adverse event (TRAE) was observed in 30 patients with grade ≥ 3 TRAEs in eight patients, the majority known on-target effects of CSF-1R inhibition. No cytomegalovirus reactivations occurred. With the 50% ORR at cycle 7 day 1, the phII cohort met the primary efficacy end point. Furthermore, the ORR in the first six cycles, an end point supporting regulatory approvals, was 82%. Responses were seen in all affected organs regardless of prior therapy. Fifty-eight percent of patients reported significant improvement in cGVHD-related symptoms using the Lee Symptom Scale. On-target activity of axatilimab was suggested by the decrease in skin CSF-1R-expressing macrophages. CONCLUSION: Targeting profibrotic macrophages with axatilimab is a therapeutically promising novel strategy with a favorable safety profile for refractory cGVHD.

Combinatorial suicide gene strategies for the safety of cell therapies.

Gene-modified cellular therapies carry inherent risks of severe and potentially fatal adverse events, including the expansion of alloreactive cells or malignant transformation due to insertional mutagenesis. Strategies to mitigate uncontrolled proliferation of gene-modified cells include co-transfection of a suicide gene, such as the inducible caspase 9 safety switch (ΔiC9). However, the activation of the ΔiC9 fails to completely eliminate all gene-modified cells. Therefore, we tested a two suicide gene system used independently or together, with the goal of complete cell elimination. The first approach combined the ΔiC9 with an inducible caspase 8, ΔiC8, which lacks the endogenous prodomain. The rationale was to use a second caspase with an alternative and complementary mechanism of action. Jurkat cells co-transduced to co-express the ΔiC8, activatable by a BB homodimerizer, and the ΔiC9 activatable by the rapamycin analog sirolimus were used in a model to estimate the degree of inducible cell elimination. We found that both agents could activate each caspase independently, with enhanced elimination with superior reduction in cell regrowth of gene-modified cells when both systems were activated simultaneously. A second approach was employed in parallel, combining the ΔiC9 with the RQR8 compact suicide gene. RQR8 incorporates a CD20 mimotope, targeted by the anti-CD20 monoclonal antibody rituxan, and the QBend10, a ΔCD34 selectable marker. Likewise, enhanced cell elimination with superior reduction in cell regrowth was observed when both systems were activated together. A dose-titration effect was also noted utilizing the BB homodimerizer, whereas sirolimus remained very potent at minimal concentrations. Further in vivo studies are needed to validate these novel combination systems, which may play a role in future cancer therapies or regenerative medicine.

Passenger Lymphocyte Syndrome and Autoimmune Hypothyroidism Following Hematopoietic Stem Cell Transplantation.

We present the case of a 24-year-old male, who received a minor ABO-incompatible allogeneic hematopoietic stem cell transplant (HSCT, blood group O+ ⟶ A+) from an HLA-matched unrelated female donor, as consolidation therapy for relapsed precursor-B-cell acute lymphoblastic leukemia. The donor had a known history of Hashimoto's thyroiditis before HSCT. At day +10 posttransplant, the patient developed severe hemolysis, which required emergent red blood cell exchange. Additionally, about a year posttransplant, he had circulating antithyroglobulin antibodies, decreased free-T4 (fT4) and increased serum thyroid-stimulating hormone (TSH). The potential causes of the posttransplant hemolytic episode and hypothyroidism are discussed. While the hemolysis was worsened by the transfusion of A red blood cells (RBCs) in the context of passenger lymphocyte syndrome, the thyroid dysfunction might be explained by an autoimmune disease transferred from the donor. The case highlights the possibility of several non-relapse-related complications of HSCT occurring in the same patient. It is critical that such adverse outcomes are distinguished from classical graft-versus-host disease (GVHD) for adequate recipient counseling, posttransplant screening, and prompt treatment.

Tumor lysis syndrome and infectious complications during treatment with venetoclax combined with azacitidine or decitabine in patients with acute myeloid leukemia.

Venetoclax (Ven) in combination with azacitidine or decitabine (hypomethylating agent; HMA) is the standard-of-care treatment for older (≥75 years) or intensive chemotherapy ineligible adults with newly diagnosed acute myeloid leukemia (AML). Tumor lysis syndrome (TLS) and infectious complications are two of the most concerning associated adverse events. We studied the real-world incidence and outcomes of these adverse events with HMA/Ven in AML patients. Our retrospective analysis included 106 patients (median age 70 years). Of these, 61 (58%) received HMA/Ven in frontline setting while 45 (42%) received in salvage setting. 19 (18%) met laboratory criteria for TLS, five (5%) developed clinical TLS (acute kidney injury). The median time to develop TLS was 2 days (range -2 to 4). During cycle 1, 29 patients (27%) were diagnosed with febrile neutropenia while 26 (25%) developed new infections. Median time to development of new infection was 10 days (1-25). Pneumonia was the most common infection (8%). Febrile neutropenia and/or new infection during cycle 1 was associated with poorer median overall survival compared to those without these complications (4.9 months vs 11.6 months; p = 0.03). In conclusion, incidence of TLS and infections was high in our cohort during initiation of HMA/Ven therapy. This data emphasizes the need for closer monitoring in these patients, especially during the first 7-10 days of treatment, which is often achieved in the inpatient setting.

Impact of access to care on 1-year mortality following allogeneic blood or marrow transplantation.

Mortality is highest in the first year following an allogeneic hematopoietic stem cell transplant. With recent advancements, we have expanded the pool of patients to whom we are able to offer transplant as a treatment option. In this context, we analyzed socioeconomic, patient, disease and transplant-related variables that predicted for 1-year all-cause, relapse-related (RRM) and non-relapse related mortality (NRM) in 304 patients at the University of Alabama at Birmingham. The 1-year overall survival, RRM and NRM rates were 60.5%, 13.5% and 22.7% respectively. A KPS score < 80, pre-transplant infection and hypertension and non-complete remission disease status adversely effected all-cause mortality. For NRM, increasing age, pre-transplant infection and diabetes, and poor access to care were associated with higher mortality whereas haploidentical donor type was associated with improved survival. For RRM, a KPS score <80, high/very high disease risk index and the presence of comorbidities were risk factors for higher mortality. Poor access to care, in addition to individual comorbidities, performance status and high-risk disease characteristics, is associated with adverse outcomes following transplant. We propose the incorporation of socioeconomic variables with patient, disease, and transplant-related variables to predict 1-year NRM.

Hematopoietic Cell Transplantation, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Hematopoietic cell transplantation (HCT) involves the infusion of hematopoietic progenitor cells into patients with hematologic disorders with the goal of re-establishing normal hematopoietic and immune function. HCT is classified as autologous or allogeneic based on the origin of hematopoietic cells. Autologous HCT uses the patient's own cells while allogeneic HCT uses hematopoietic cells from a human leukocyte antigen-compatible donor. Allogeneic HCT is a potentially curative treatment option for patients with certain types of hematologic malignancies, and autologous HCT is primarily used to support patients undergoing high-dose chemotherapy. Advances in HCT methods and supportive care in recent decades have led to improved survival after HCT; however, disease relapse and posttransplant complications still commonly occur in both autologous and allogeneic HCT recipients. Allogeneic HCT recipients may also develop acute and/or chronic graft-versus-host disease (GVHD), which results in immune-mediated cellular injury of several organs. The NCCN Guidelines for Hematopoietic Cell Transplantation focus on recommendations for pretransplant recipient evaluation and the management of GVHD in adult patients with malignant disease.

Observation Versus Immediate Reinduction for Acute Myeloid Leukemia Patients With Indeterminate Day 14 Bone Marrow Results.

INTRODUCTION: The benefit of immediate reinduction chemotherapy for patients with indeterminate day 14 bone marrow results (≤ 20% cellularity and 5%-20% blasts) remains unclear. We report our experience with patients with acute myeloid leukemia (AML) with indeterminate day 14 bone marrow biopsy results treated with reinduction chemotherapy versus observation alone. MATERIALS AND METHODS: We performed a retrospective study to assess the outcomes of adult patients with newly diagnosed AML treated with or without reinduction chemotherapy for indeterminate day 14 bone marrow results. RESULTS: We identified 50 patients with indeterminate day 14 bone marrow results. Of the 50 patients, 25 (50%) had received reinduction therapy and 25 (50%) had not. Of the 50 patients, 24 (48%) had poor risk disease, 12 in the reinduction arm (10 with an abnormal karyotype and 2 with a normal karyotype with molecular abnormalities) and 12 in the observation arm (6 with an abnormal karyotype and 6 with a normal karyotype with molecular abnormalities). The overall response rate (complete remission plus complete remission with incomplete count recovery) was similar in both treatment arms (80% vs. 80%). No statistically significant difference was found in the median overall survival (13 months vs. 21 months; P = .88) or relapse-free survival (13 months vs. 33 months; P = .53) between the 2 treatment arms. CONCLUSION: Our study did not find a statistically significant difference in the overall response rates or survival outcome measures for patients with AML and indeterminate day 14 bone marrow in the 2 treatment groups. Our findings question the utility of immediate reinduction chemotherapy and raise concern regarding overtreatment in this patient population. Larger studies investigating similar outcomes are warranted to validate our clinical findings.

Gilteritinib or Chemotherapy for Relapsed or Refractory FLT3-Mutated AML.

BACKGROUND: Patients with relapsed or refractory acute myeloid leukemia (AML) with mutations in the FMS-like tyrosine kinase 3 gene (FLT3) infrequently have a response to salvage chemotherapy. Gilteritinib is an oral, potent, selective FLT3 inhibitor with single-agent activity in relapsed or refractory FLT3-mutated AML. METHODS: In a phase 3 trial, we randomly assigned adults with relapsed or refractory FLT3-mutated AML in a 2:1 ratio to receive either gilteritinib (at a dose of 120 mg per day) or salvage chemotherapy. The two primary end points were overall survival and the percentage of patients who had complete remission with full or partial hematologic recovery. Secondary end points included event-free survival (freedom from treatment failure [i.e., relapse or lack of remission] or death) and the percentage of patients who had complete remission. RESULTS: Of 371 eligible patients, 247 were randomly assigned to the gilteritinib group and 124 to the salvage chemotherapy group. The median overall survival in the gilteritinib group was significantly longer than that in the chemotherapy group (9.3 months vs. 5.6 months; hazard ratio for death, 0.64; 95% confidence interval [CI], 0.49 to 0.83; P<0.001). The median event-free survival was 2.8 months in the gilteritinib group and 0.7 months in the chemotherapy group (hazard ratio for treatment failure or death, 0.79; 95% CI, 0.58 to 1.09). The percentage of patients who had complete remission with full or partial hematologic recovery was 34.0% in the gilteritinib group and 15.3% in the chemotherapy group (risk difference, 18.6 percentage points; 95% CI, 9.8 to 27.4); the percentages with complete remission were 21.1% and 10.5%, respectively (risk difference, 10.6 percentage points; 95% CI, 2.8 to 18.4). In an analysis that was adjusted for therapy duration, adverse events of grade 3 or higher and serious adverse events occurred less frequently in the gilteritinib group than in the chemotherapy group; the most common adverse events of grade 3 or higher in the gilteritinib group were febrile neutropenia (45.9%), anemia (40.7%), and thrombocytopenia (22.8%). CONCLUSIONS: Gilteritinib resulted in significantly longer survival and higher percentages of patients with remission than salvage chemotherapy among patients with relapsed or refractory FLT3-mutated AML. (Funded by Astellas Pharma; ADMIRAL ClinicalTrials.gov number, NCT02421939.).

Italian survey on cetuximab-based therapy of elderly patients with metastatic colorectal cancer.

PURPOSE: There is no consensus on the use of cetuximab in elderly patients with metastatic colorectal cancer. To this end, a survey was carried in 17 Italian oncology centers. METHODS: The centers answered a 29-item questionnaire structured as follows: (i) demographic characteristics; (ii) medical history; (iii) assessment of RAS/BRAF mutations and DPD/UGT polymorphism before treatment; (iv) treatment schemes and side effects; (v) geriatric assessment and customization of treatment. RESULTS: One-third of patients are over 80 years old. The RAS/BRAF mutational status is not primarily evaluated by 17.6% of the centers, while DPD and UGT polymorphism is not evaluated by 82.4% and 76.5% of the centers. The most common therapeutic scheme is cetuximab/FOLFIRI and diarrhea is the main cause of suspension/reduction of treatment. The 70% of centers use systemic tetracyclines for skin toxicity. The 23.5% of the centers do not carry out any geriatric evaluation before the start of the therapy and those who perform it prefer the G8 (70.6%) and VES-13 (29.4%) scales. CONCLUSIONS: Greater efforts should be made to improve the evaluation of the patient both about mutational and genetic procedures with geriatric evaluation. As for cetuximab in elderly patients, randomized studies are needed to provide guidance to physicians.

Generation of Suicide Gene-Modified Chimeric Antigen Receptor-Redirected T-Cells for Cancer Immunotherapy.

Chimeric antigen receptor (CAR)-redirected T-cells are a powerful tool for the treatment of several type of cancers; however, they can cause several adverse effects including cytokine release syndrome, off-target effects resulting in potentially fatal organ damage or even death. Particularly, for CAR T-cells redirected toward acute myeloid leukemia (AML) antigens myelosuppression can be a challenge. The previously validated inducible Caspase9 (iC9) suicide gene system is one of the approaches to control the infused cells in vivo through its activation with a nontherapeutic chemical inducer of dimerizer (CID). We performed a preclinical validation using a model of CD33+ AML, and generated iC9 CAR T-cells co-expressing a CAR targeting the AML-associated antigen CD33 and a selectable marker (ΔCD19). ΔCD19 selected (sel.) iC9-CAR.CD33 T-cells were effective in controlling leukemia growth in vitro, and could be partially eliminated (76%) using a chemical inducer of dimerization that activates iC9. Moreover, to completely eliminate residual cells, a second targeted agent was added. Future plans with these methods are to investigate the utility of iC9-CAR.CD33 T-cells as part of the conditioning therapy for an allogeneic hematopoietic stem cell transplant. Additional strategies that we are currently validating include (1) the modulation of the suicide gene activation, using different concentrations of the inducing agent(s), to be able to eliminate CAR T-cells modified by a regulatable gene, ideally aiming at preserving a proportion of the infused cells (and their antitumor activity) for mild to moderate toxicities, or (2) the co-expression of an inhibitory CAR aiming at sparing normal cells co-expressing an antigen not shared with the tumor.

Reduced intensity vs. myeloablative conditioning with fludarabine and PK-guided busulfan in allogeneic stem cell transplantation for patients with AML/MDS.

Conditioning regimens contribute significantly to outcomes following allogeneic stem cell transplantation (allo-SCT). Reduced-intensity conditioning (RIC) regimens provide lower toxicity at the cost of reduced efficacy compared with myeloablative conditioning (MAC) regimens. However, because pre-transplant prognostic variables often determine the conditioning regimen, studies of RIC vs. MAC have been inconclusive. We present a retrospective analysis of 242 acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) patients, 112 of whom were in 56 pairs matched using propensity scores, to account for variation that may confound clinical outcomes. The uniform conditioning regimens consisted of fludarabine with pharmacokinetic (PK)-guided intravenous busulfan (Bu). The RIC and MAC regimens were dosed at the average daily area under the concentration-vs-time curve (AUC) of 4000 µMol min and 5000-6000 µMol min, or total course AUC of 16,000 µMol min and 20,000-24,000 µMol min, respectively; PK-guided dosing removes overlap in systemic Bu exposure. When patients' data were propensity-matched, there was a trend toward significantly increased full donor chimerism and decreased chronic graft vs. host disease in RIC, and no significant differences in progression free survival and overall survival between RIC and MAC. Our results also elucidate the efficacy of PK-guided-dosing in the setting of allo-SCT for AML and MDS.

Exploiting Cell Death Pathways for Inducible Cell Elimination to Modulate Graft-versus-Host-Disease.

Hematopoietic stem cell transplantation is a potent form of immunotherapy, potentially life-saving for many malignant hematologic diseases. However, donor lymphocytes infused with the graft while exerting a graft versus malignancy effect can also cause potentially fatal graft versus host disease (GVHD). Our group has previously validated the inducible caspase-9 suicide gene in the haploidentical stem cell transplant setting, which proved successful in reversing signs and symptoms of GVHD within hours, using a non-therapeutic dimerizing agent. Cellular death pathways such as apoptosis and necroptosis are important processes in maintaining healthy cellular homeostasis within the human body. Here, we review two of the most widely investigated cell death pathways active in T-cells (apoptosis and necroptosis), as well as the emerging strategies that can be exploited for the safety of T-cell therapies. Furthermore, such strategies could be exploited for the safety of other cellular therapeutics as well.

Correction: In Vitro Pre-Clinical Validation of Suicide Gene Modified Anti-CD33 Redirected Chimeric Antigen Receptor T-Cells for Acute Myeloid Leukemia.

[This corrects the article DOI: 10.1371/journal.pone.0166891.].

In Vitro Pre-Clinical Validation of Suicide Gene Modified Anti-CD33 Redirected Chimeric Antigen Receptor T-Cells for Acute Myeloid Leukemia.

BACKGROUND: Approximately fifty percent of patients with acute myeloid leukemia can be cured with current therapeutic strategies which include, standard dose chemotherapy for patients at standard risk of relapse as assessed by cytogenetic and molecular analysis, or high-dose chemotherapy with allogeneic hematopoietic stem cell transplant for high-risk patients. Despite allogeneic hematopoietic stem cell transplant about 25% of patients still succumb to disease relapse, therefore, novel strategies are needed to improve the outcome of patients with acute myeloid leukemia. METHODS AND FINDINGS: We developed an immunotherapeutic strategy targeting the CD33 myeloid antigen, expressed in ~ 85-90% of patients with acute myeloid leukemia, using chimeric antigen receptor redirected T-cells. Considering that administration of CAR T-cells has been associated with cytokine release syndrome and other potential off-tumor effects in patients, safety measures were here investigated and reported. We genetically modified human activated T-cells from healthy donors or patients with acute myeloid leukemia with retroviral supernatant encoding the inducible Caspase9 suicide gene, a ΔCD19 selectable marker, and a humanized third generation chimeric antigen receptor recognizing human CD33. ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells had a 75±3.8% (average ± standard error of the mean) chimeric antigen receptor expression, were able to specifically lyse CD33+ targets in vitro, including freshly isolated leukemic blasts from patients, produce significant amount of tumor-necrosis-factor-alpha and interferon-gamma, express the CD107a degranulation marker, and proliferate upon antigen specific stimulation. Challenging ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells with programmed-death-ligand-1 enriched leukemia blasts resulted in significant killing like observed for the programmed-death-ligand-1 negative leukemic blasts fraction. Since the administration of 10 nanomolar of a non-therapeutic dimerizer to activate the suicide gene resulted in the elimination of only 76.4±2.0% gene modified cells in vitro, we found that co-administration of the dimerizer with either the BCL-2 inhibitor ABT-199, the pan-BCL inhibitor ABT-737, or mafosfamide, resulted in an additive effect up to complete cell elimination. CONCLUSIONS: This strategy could be investigated for the safety of CAR T-cell applications, and targeting CD33 could be used as a 'bridge" therapy for patients coming to allogeneic hematopoietic stem cell transplant, as anti-leukemia activity from infusing CAR.CD33 T-cells has been demonstrated in an ongoing clinical trial. Albeit never performed in the clinical setting, our future plan is to investigate the utility of iC9-CAR.CD33 T-cells as part of the conditioning therapy for an allogeneic hematopoietic stem cell transplant for acute myeloid leukemia, together with other myelosuppressive agents, whilst the activation of the inducible Caspase9 suicide gene would grant elimination of the infused gene modified T-cells prior to stem cell infusion to reduce the risk of engraftment failure as the CD33 is also expressed on a proportion of the donor stem cell graft.