Parvovirus B19-associated graft failure after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Parvovirus B19 (PVB19) infection has been implicated in allograft failure or dysfunction in solid organ transplantation (SOT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the literature is limited. CASE: Two pediatric patients were diagnosed with PVB19 infection around the time of allo-HSCT graft failure. Both cases were secondary graft failure and required second allo-HSCT. CONCLUSION: There are many risk factors and potential confounders in determining the exact etiology of graft failure after allo-HSCT. These two cases highlight the importance of including PVB19 in the diagnostic evaluation for graft failure. PVB19 infection may be an important risk factor for allo-HSCT graft failure.

Comparison of SP142 and 22C3 Immunohistochemistry PD-L1 Assays for Clinical Efficacy of Atezolizumab in Non-Small Cell Lung Cancer: Results From the Randomized OAK Trial.

BACKGROUND: This phase III OAK trial (NCT02008227) subgroup analysis (data cutoff, January 9, 2019) evaluated the predictive value of 2 PD-L1 IHC tests (VENTANA SP142 and Dako 22C3) for benefit from atezolizumab versus docetaxel by programmed death ligand 1 (PD-L1) status in patients with previously treated metastatic non-small cell lung cancer. METHODS: PD-L1 expression was assessed prospectively with SP142 on tumor cells (TC) and tumor-infiltrating immune cells (IC) and retrospectively with 22C3 using a tumor proportion score (TPS) based on TC membrane staining. Efficacy was assessed in the 22C3 biomarker-evaluable population (22C3-BEP) (n = 577; 47.1% of SP142-intention-to-treat population) and non-22C3-BEP (n = 648) in PD-L1 subgroups (high, low, and negative) and according to selection by 1 or both assays. RESULTS: In the 22C3-BEP, overall survival benefits with atezolizumab versus docetaxel were observed across PD-L1 subgroups; benefits were greatest in SP142-defined PD-L1-high (TC3 or IC3: hazard ratio [HR], 0.39 [95% confidence interval (CI), 0.25-0.63]) and 22C3-defined PD-L1-high (TPS ≥ 50%: HR, 0.56 [95% CI, 0.38-0.82]) and low (TPS, 1% to < 50%: HR, 0.55 [95% CI, 0.37-0.82]) groups. Progression-free survival improved with increasing PD-L1 expression for both assays. SP142 and 22C3 assays identified overlapping and unique patient populations in PD-L1-high, positive, and negative subgroups. Overall survival and progression-free survival benefits favored atezolizumab over docetaxel in double PD-L1-positive and negative groups; patients with both SP142- and 22C3-positive tumors derived the greatest benefit. CONCLUSIONS: Despite different scoring algorithms and differing sensitivity levels, the SP142 and 22C3 assays similarly predicted atezolizumab benefit at validated PD-L1 thresholds in patients with non-small cell lung cancer.

Atezolizumab Versus Docetaxel in Pretreated Patients With NSCLC: Final Results From the Randomized Phase 2 POPLAR and Phase 3 OAK Clinical Trials.

INTRODUCTION: The phase 2 POPLAR and phase 3 OAK studies of the anti-programmed death-ligand 1 (PD-L1) immunotherapy atezolizumab in patients with previously treated advanced NSCLC revealed significant improvements in survival versus docetaxel (p = 0.04 and 0.0003, respectively). Longer follow-up permits evaluation of continued benefit of atezolizumab. This study reports the final overall survival (OS) and safety findings from both trials. METHODS: POPLAR randomized 287 patients (atezolizumab, 144; docetaxel, 143) and OAK randomized 1225 patients (atezolizumab, 613; docetaxel, 612). The patients received atezolizumab (1200 mg fixed dose) or docetaxel (75 mg/m2) every 3 weeks. Efficacy and safety outcomes were evaluated. RESULTS: A longer OS was observed in patients receiving atezolizumab versus docetaxel in POPLAR (median OS = 12.6 mo versus 9.7 mo; hazard ratio = 0.76, 95% confidence interval [CI]: 0.58-1.00) and OAK (median OS = 13.3 versus 9.8 mo; hazard ratio = 0.78, 95% CI: 0.68-0.89). The 4-year OS rates in POPLAR were 14.8% (8.7-20.8) and 8.1% (3.2-13.0) and those in OAK were 15.5% (12.4-18.7) and 8.7% (6.2-11.3) for atezolizumab and docetaxel, respectively. Atezolizumab had improved OS benefit compared with docetaxel across all PD-L1 expression and histology groups. Most 4-year survivors in the docetaxel arms received subsequent immunotherapy (POPLAR, 50%; OAK, 65%). Of the 4-year survivors, most had Eastern Cooperative Oncology Group performance status of 0 and nonsquamous histological classification and approximately half were responders (POPLAR: atezolizumab, seven of 15; docetaxel, three of four; OAK: atezolizumab, 24 of 43; docetaxel, 11 of 26). Treatment-related grade 3/4 adverse events occurred in 27% and 16% of atezolizumab 4-year survivors in POPLAR and OAK, respectively. CONCLUSIONS: Long-term follow-up suggests a consistent survival benefit with atezolizumab versus docetaxel in patients with previously treated NSCLC regardless of PD-L1 expression, histology, or subsequent immunotherapy. Atezolizumab had no new safety signals, and the safety profile was similar to that in previous studies.

Atezolizumab Treatment Beyond Progression in Advanced NSCLC: Results From the Randomized, Phase III OAK Study.

INTRODUCTION: Cancer immunotherapy may alter tumor biology such that treatment effects can extend beyond radiographic progression. In the randomized, phase III OAK study of atezolizumab (anti-programmed death-ligand 1) versus docetaxel in advanced NSCLC, overall survival (OS) benefit with atezolizumab was observed in the overall patient population, without improvement in objective response rate (ORR) or progression-free survival (PFS). We examine the benefit-risk of atezolizumab treatment beyond progression (TBP). METHODS: Eight hundred fifty patients included in the OAK primary efficacy analysis were evaluated. Atezolizumab was continued until loss of clinical benefit. Docetaxel was administered until Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) disease progression (PD)/unacceptable toxicity; no crossover to atezolizumab was allowed. ORR, PFS, post-PD OS, target lesion change, and safety were evaluated. RESULTS: In atezolizumab-arm patients, ORR was 16% versus 14% and median PFS was 4.2 versus 2.8 months per immune-modified RECIST versus RECIST v1.1. The median post-PD OS was 12.7 months (95% confidence interval [CI]: 9.3-14.9) in 168 atezolizumab-arm patients continuing TBP, 8.8 months (95% CI: 6.0-12.1) in 94 patients switching to nonprotocol therapy, and 2.2 months (95% CI: 1.9-3.4) in 70 patients receiving no further therapy. Of the atezolizumab TBP patients, 7% achieved a post-progression response in target lesions and 49% had stable target lesions. Atezolizumab TBP was not associated with increased safety risks. CONCLUSIONS: Within the limitations of this retrospective analysis, the post-PD efficacy and safety data from OAK are consistent with a positive benefit-risk profile of atezolizumab TBP in patients performing well clinically at the time of PD.

Patient-Reported Outcomes in OAK: A Phase III Study of Atezolizumab Versus Docetaxel in Advanced Non-Small-cell Lung Cancer.

BACKGROUND: The randomized phase III OAK (a study of atezolizumab compared with docetaxel in participants with locally advanced or metastatic non-small-cell lung cancer [NSCLC] who have failed platinum-containing therapy) trial investigated the anti-programmed cell death ligand 1 (PD-L1) antibody atezolizumab for advanced or metastatic, previously treated, NSCLC. Atezolizumab significantly improved overall survival (OS) compared with docetaxel (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.62-0.87; P = .0003; median OS, 13.8 vs. 9.6 months, respectively). Patient-reported outcomes (PROs) were collected to evaluate disease-related symptoms and health-related quality of life (HRQoL) to support the finding of a survival benefit. PATIENTS AND METHODS: The first 850 patients were randomized to receive atezolizumab (1200 mg every 3 weeks) or docetaxel (75 mg/m2 every 3 weeks). PROs were collected on day 1 of cycle 1, day 1 of every subsequent cycle, and at the end-of-treatment visit for patients who completed ≥ 1 baseline and 1 postbaseline PRO assessment. The European Organisation for the Research and Treatment of Cancer QoL questionnaire and lung cancer module were used to assess PROs. RESULTS: Atezolizumab delayed the time to deterioration (TTD) in physical function (HR, 0.75; 95% CI, 0.58-0.98) and role function (HR, 0.79; 95% CI, 0.62-1.00) and numerically improved patients' HRQoL from baseline compared with docetaxel. Atezolizumab also prolonged the TTD in chest pain (HR, 0.71; 95% CI, 0.49-1.05; P = .0823), although both arms showed an objective reduction relative to baseline. Overall, the patients had no clinically significant worsening in treatment-related symptoms, although the scores favored atezolizumab. CONCLUSION: These PRO data support the clinical benefit of atezolizumab in patients with previously treated advanced or metastatic NSCLC. Atezolizumab prolonged the TTD of patients' limitations in role and physical functions compared with docetaxel.

Updated Efficacy Analysis Including Secondary Population Results for OAK: A Randomized Phase III Study of Atezolizumab versus Docetaxel in Patients with Previously Treated Advanced Non-Small Cell Lung Cancer.

INTRODUCTION: The efficacy and safety of atezolizumab versus the efficacy and safety of docetaxel as second- or third-line treatment in patients with advanced NSCLC in the primary (n = 850) and secondary (n = 1225) efficacy populations of the randomized phase III OAK study (respectively referred to as the intention-to-treat [ITT] 850 [ITT850] and ITT1225) at an updated data cutoff were assessed. METHODS: Patients received atezolizumab, 1200 mg, or docetaxel, 75 mg/m2, intravenously every 3 weeks until loss of clinical benefit or disease progression, respectively. The primary end point was overall survival (OS) in the ITT population and programmed death-ligand 1-expressing subgroup. A sensitivity analysis was conducted to evaluate the impact of subsequent immunotherapy use in the docetaxel arm on the observed survival benefit with atezolizumab. RESULTS: Atezolizumab demonstrated an OS benefit versus docetaxel in the updated ITT850 (hazard ratio [HR] = 0.75, 95% confidence interval: 0.64-0.89, p = 0.0006) and the ITT1225 (HR = 0.80, 95% confidence interval: 0.70-0.92, p = 0.0012) after minimum follow-up times of 26 and 21 months, respectively. Improved survival with atezolizumab was observed across programmed death-ligand 1 and histological subgroups. In the immunotherapy sensitivity analysis, the relative OS benefit with atezolizumab was slightly greater in the ITT850 (HR = 0.69) and ITT1225 (HR = 0.74) than the conventional OS estimate. Fewer patients receiving atezolizumab experienced grade 3 or 4 treatment-related adverse events (14.9%) than did patients receiving docetaxel (42.4%); no grade 5 adverse events related to atezolizumab were observed. CONCLUSIONS: The results of the updated ITT850 and initial ITT1225 analyses were consistent with those of the primary efficacy analysis demonstrating survival benefit with atezolizumab versus with docetaxel. Atezolizumab continued to demonstrate a favorable safety profile after longer treatment exposure and follow-up.

Next-generation NAMPT inhibitors identified by sequential high-throughput phenotypic chemical and functional genomic screens.

Phenotypic high-throughput chemical screens allow for discovery of small molecules that modulate complex phenotypes and provide lead compounds for novel therapies; however, identification of the mechanistically relevant targets remains a major experimental challenge. We report the application of sequential unbiased high-throughput chemical and ultracomplex small hairpin RNA (shRNA) screens to identify a distinctive class of inhibitors that target nicotinamide phosphoribosyl transferase (NAMPT), a rate-limiting enzyme in the biosynthesis of nicotinamide adenine dinucleotide, a crucial cofactor in many biochemical processes. The lead compound STF-118804 is a highly specific NAMPT inhibitor, improves survival in an orthotopic xenotransplant model of high-risk acute lymphoblastic leukemia, and targets leukemia stem cells. Tandem high-throughput screening using chemical and ultracomplex shRNA libraries, therefore, provides a rapid chemical genetics approach for seamless progression from small-molecule lead identification to target discovery and validation.

Runx1 dose-dependently regulates endochondral ossification during skeletal development and fracture healing.

Runx1 is expressed in skeletal elements, but its role in fracture repair has not been analyzed. We created mice with a hypomorphic Runx1 allele (Runx1(L148A) ) and generated Runx1(L148A/-) mice in which >50% of Runx1 activity was abrogated. Runx1(L148A/-) mice were viable but runted. Their growth plates had extended proliferating and hypertrophic zones, and the percentages of Sox9-, Runx2-, and Runx3-positive cells were decreased. Femoral fracture experiments revealed delayed cartilaginous callus formation, and the expression of chondrogenic markers was decreased. Conditional ablation of Runx1 in the mesenchymal progenitor cells of the limb with Prx1-Cre conferred no obvious limb phenotype; however, cartilaginous callus formation was delayed following fracture. Embryonic limb bud-derived mesenchymal cells showed delayed chondrogenesis when the Runx1 allele was deleted ex vivo with adenoviral-expressed Cre. Collectively, our data suggest that Runx1 is required for commitment and differentiation of chondroprogenitor cells into the chondrogenic lineage.

GSK-3 promotes conditional association of CREB and its coactivators with MEIS1 to facilitate HOX-mediated transcription and oncogenesis.

Acute leukemias induced by MLL chimeric oncoproteins are among the subset of cancers distinguished by a paradoxical dependence on GSK-3 kinase activity for sustained proliferation. We demonstrate here that GSK-3 maintains the MLL leukemia stem cell transcriptional program by promoting the conditional association of CREB and its coactivators TORC and CBP with homedomain protein MEIS1, a critical component of the MLL-subordinate program, which in turn facilitates HOX-mediated transcription and transformation. This mechanism also applies to hematopoietic cells transformed by other HOX genes, including CDX2, which is highly expressed in a majority of acute myeloid leukemias, thus providing a molecular approach based on GSK-3 inhibitory strategies to target HOX-associated transcription in a broad spectrum of leukemias.

Hierarchical maintenance of MLL myeloid leukemia stem cells employs a transcriptional program shared with embryonic rather than adult stem cells.

The genetic programs that promote retention of self-renewing leukemia stem cells (LSCs) at the apex of cellular hierarchies in acute myeloid leukemia (AML) are not known. In a mouse model of human AML, LSCs exhibit variable frequencies that correlate with the initiating MLL oncogene and are maintained in a self-renewing state by a transcriptional subprogram more akin to that of embryonic stem cells (ESCs) than to that of adult stem cells. The transcription/chromatin regulatory factors Myb, Hmgb3, and Cbx5 are critical components of the program and suffice for Hoxa/Meis-independent immortalization of myeloid progenitors when coexpressed, establishing the cooperative and essential role of an ESC-like LSC maintenance program ancillary to the leukemia-initiating MLL/Hox/Meis program. Enriched expression of LSC maintenance and ESC-like program genes in normal myeloid progenitors and poor-prognosis human malignancies links the frequency of aberrantly self-renewing progenitor-like cancer stem cells (CSCs) to prognosis in human cancer.

Disease mutations in RUNX1 and RUNX2 create nonfunctional, dominant-negative, or hypomorphic alleles.

Monoallelic RUNX1 mutations cause familial platelet disorder with predisposition for acute myelogenous leukemia (FPD/AML). Sporadic mono- and biallelic mutations are found at high frequencies in AML M0, in radiation-associated and therapy-related myelodysplastic syndrome and AML, and in isolated cases of AML M2, M5a, M3 relapse, and chronic myelogenous leukemia in blast phase. Mutations in RUNX2 cause the inherited skeletal disorder cleidocranial dysplasia (CCD). Most hematopoietic missense mutations in Runx1 involve DNA-contacting residues in the Runt domain, whereas the majority of CCD mutations in Runx2 are predicted to impair CBFbeta binding or the Runt domain structure. We introduced different classes of missense mutations into Runx1 and characterized their effects on DNA and CBFbeta binding by the Runt domain, and on Runx1 function in vivo. Mutations involving DNA-contacting residues severely inactivate Runx1 function, whereas mutations that affect CBFbeta binding but not DNA binding result in hypomorphic alleles. We conclude that hypomorphic RUNX2 alleles can cause CCD, whereas hematopoietic disease requires more severely inactivating RUNX1 mutations.

Runx1 is expressed in adult mouse hematopoietic stem cells and differentiating myeloid and lymphoid cells, but not in maturing erythroid cells.

The transcription factor Runx1 marks all functional hematopoietic stem cells (HSCs) in the embryo and is required for their generation. Mutations in Runx1 are found in approximately 25% of acute leukemias and in familial platelet disorder, suggesting a role for Runx1 in adult hematopoiesis as well. A comprehensive analysis of Runx1 expression in adult hematopoiesis is lacking. Here we show that Runx1 is expressed in functional HSCs in the adult mouse, as well as in cells with spleen colony-forming unit (CFU) and culture CFU capacities. Additionally, we document Runx1 expression in all hematopoietic lineages at the single cell level. Runx1 is expressed in the majority of myeloid cells and in a smaller proportion of lymphoid cells. Runx1 expression substantially decreases during erythroid differentiation. We also document effects of reduced Runx1 levels on adult hematopoiesis.

Energetic contribution of residues in the Runx1 Runt domain to DNA binding.

Core-binding factors (CBFs) are a small family of heterodimeric transcription factors that play critical roles in hematopoiesis and in the development of bone, stomach epithelium, and proprioceptive neurons. Mutations in CBF genes are found in leukemias, bone disorders, and gastric cancer. CBFs consist of a DNA-binding CBF alpha subunit and a non-DNA-binding CBF beta subunit. DNA binding and heterodimerization with CBF beta are mediated by the Runt domain in CBF alpha. Here we report an alanine-scanning mutagenesis study of the Runt domain that targeted amino acids identified by structural studies to reside at the DNA or CBF beta interface, as well as amino acids mutated in human disease. We determined the energy contributed by each of the DNA-contacting residues in the Runt domain to DNA binding both in the absence and presence of CBF beta. We propose mechanisms by which mutations in the Runt domain found in hematopoietic and bone disorders affect its affinity for DNA.