Inferior survival after microbiota injury: A multicenter allo-HCT study

7015

Background: Relationships between microbiota composition and clinical outcomes following allogeneic hematopoietic cell transplantation (allo-HCT) have been described in single-center studies. Geographic variations in human microbial communities and differences in clinical practices across institutions raise the question of whether these associations are generalizable. We report the first multi-center study of the intestinal microbiota in allo-HCT. Methods: Intestinal communities in 8,768 fecal samples from 1,362 allo-HCT patients at 4 centers on 3 continents were profiled by 16S sequencing. Associations between microbiota composition and clinical outcomes were analyzed with proportional-hazards analysis in an observational study. Results: We observed reproducible patterns of microbiota injury characterized by loss of diversity and domination by single taxa. Low diversity in the neutrophil engraftment period was reproducibly associated with increased risk of death (multivariate HR 0.48 [0.30-0.77] p = 0.002 in the largest cohort). These reductions in OS were in part due to an increased risk of transplant-related mortality and graft-vs-host disease. Baseline pre-HCT samples already bore evidence of microbiome disruption; low diversity prior to transplantation was associated with poor survival. A bacterial-composition risk score that was trained in one cohort predicted mortality in the other three cohorts (multivariate HR 1.42 [1.04-1.93] p = 0.03), indicating that not only a diversity metric but also a signature of specific bacterial abundances is informative about post-HCT mortality risk across independent institutions. Conclusions: We demonstrate a relationship between microbiota and survival after allo-HCT that is independent of transplant center and geographic location. The diversity of clinical practices across institutions imposed significant heterogeneity in the study, yet we observed reproducible microbiota injury patterns and associations with outcomes. This concordance suggests that approaches to manipulate the intestinal microbiota in allo-HCT may be generalizable.

Impact of geriatric vulnerability on outcomes of older patients in allogeneic hematopoietic cell transplantation

7017

Background: Older patients are at increased risk for complications and death following allogeneic hematopoietic cell transplantation (allo-HCT). Traditional transplant-specific prognostic indices such as hematopoietic cell transplant comorbidity index (HCT-CI) may not capture all underlying geriatric vulnerabilities, and in-depth evaluation by a geriatrician prior to transplant may not always be available. We hypothesize that routine pre-transplant assessments by interdisciplinary clinical providers may help uncover additional geriatric deficits. Methods: Using an institutional database of 457 adults age 60 years and older (range 60-78.7) who underwent first allo-HCT for hematological malignancies from 2010 to 2017, we retrospectively examined the prevalence and the prognostic impact of pre-transplant geriatric deficits identified by interdisciplinary clinical providers including geriatric domains of functional activity, cognition, medication, nutrition, mobility, and routine laboratory tests. Results: With a median follow-up of 37 months for survivors, the 3-year probability of overall survival (OS) was 50% (95% CI 45-55). The 2-year cumulative incidence of non-relapse mortality (NRM) was 25% (95% CI 22-28). Among pre-transplant geriatric variables, we found that impairment in instrumental activities of daily living (IADL) was associated with increased NRM and inferior PFS and OS. In multivariate analyses, mismatched donor, age-adjusted HCT-CI > 4 (aaHCTCI), and IADL impairment were associated with NRM, while high/very high disease risk index (DRI), IADL impairment, and positive CMV status were associated with OS. The combination of IADL impairment with either aaHCTCI or DRI readily stratifies NRM and OS, respectively. Conclusions: Our findings establish a simple assessment tool to risk stratify older patients prior to allo-HCT using IADL and aaHCTCI and DRI. These results may provide an entry point for prospective, interventional trials to reduce NRM and toxicities for older allo-HCT patients.

Ixazomib and dexamethasone in high risk smoldering multiple myeloma: A clinical and correlative pilot study

8051

Background: Patients with high risk smoldering multiple myeloma (HR-SMM) have an increased risk of progression to multiple myeloma (MM)- median time < 2 years. The standard management of these patients currently is close clinical monitoring; however, randomized trials show longer progression-free and overall survival in in HR-SMM patients treated with the oral immunomodulatory drug lenalidomide. We report the use ixazomib, the first oral proteasome inhibitor, in combination with dexamethasone in the setting of HR-SMM. Because proteasome inhibitors can provide deep clinical responses in patients with MM, we set the pre-specified threshold for efficacy high (overall response rate of ≥75%). Methods: In this single arm pilot trial of ixazomib/dexamethasone, patients received 12 4-week cycles of ixazomib/dexamethasone followed by ixazomib maintenance for 24 cycles. The primary endpoint is best overall response after 12 cycles and second objectives include duration of response, safety, and progression free survival. Results: 14 patients with HR-SMM were enrolled between 06/2016 and 03/2018. The median age is 65 years and 10 (71%) of patients were male. 11 (79%) patients were high-risk by the PETHEMA criteria, 2 (14%) by the Mayo Clinic criteria and 1 (7%) by both. At data cut-off (02/07/2019), patients completed a median of 17 cycles and 10 (71%) are continuing treatment. 4 patients have stopped treatment (2 patients for raise in serum markers without progression to MM, and 1 each for toxicities, and co-morbidities unrelated to treatment). 9 (64%) achieved an objective response (8 PR, and 1 VGPR) and no patient has progressed to MM. Non-heme adverse events included 3 grade 1 GI events, 2 grade 3 lung infection, 1 grade 2 acute kidney injury, and 1 had grade 1 fatigue that was possibly related to treatment. Conclusions: Ixazomib/dexamethasone appears well tolerated with high overall response (9/14; 64%) in patients with HR-SMM. Although the trial does not meet our pre-specified threshold for efficacy (i.e. best overall response rate of 75%), with a median follow-up of 17 months, no patient progressed to MM and only 2 patients had serologic progression. These results support further evaluation of ixazomib/dexamethasone alone and in combination with other agents as treatment for patients with HR-SMM. Clinical trial information: NCT02697383.

Safety and tolerability of conditioning chemotherapy followed by CD19-targeted CAR T cells for relapsed/refractory CLL

BACKGROUND

Subgroups of patients with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) exhibit suboptimal outcomes after standard therapies, including oral kinase inhibitors. We and others have previously reported on safety and efficacy of autologous CD19-targeted CAR T-cells for these patients; here we report safety and long-term follow-up of CAR T-cell therapy with or without conditioning chemotherapy for patients with R/R CLL and indolent B-cell non-Hodgkin lymphoma (B-NHL).

METHODS

We conducted a phase 1 clinical trial investigating CD19-targeted CAR T-cells incorporating a CD28 costimulatory domain (19-28z). Seventeen of 20 patients received conditioning chemotherapy prior to CAR T-cell infusion. Five patients with CLL received ibrutinib at the time of autologous T-cell collection and/or CAR T-cell administration.

RESULTS

This analysis included 16 patients with R/R CLL and 4 patients with R/R indolent B-NHL. Cytokine release syndrome (CRS) was observed in all 20 patients but grades 3 and 4 CRS and neurological events were uncommon (10% for each). Ex vivo expansion of T-cells and proportions of CD4+/CD8+ CAR T-cells with CD62L+CD127+ immunophenotype were significantly greater in patients on ibrutinib at leukapheresis. Three of 12 evaluable CLL patients receiving conditioning chemotherapy achieved CR (two had minimal residual disease-negative CR). All patients achieving CR remained progression-free at median follow-up of 53 months.

CONCLUSION

Conditioning chemotherapy and 19-28z CAR T-cells were acceptably tolerated across investigated dose levels in heavily pretreated patients with R/R CLL and indolent B-NHL, and a subgroup of patients achieved durable CR. Ibrutinib therapy may modulate autologous T-cell phenotype.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00466531.

FUNDING

Juno Therapeutics.

Baseline identification of clonal V(D)J sequences for DNA-based minimal residual disease detection in multiple myeloma

Tracking of clonal immunoglobulin V(D)J rearrangement sequences by next generation sequencing is highly sensitive for minimal residual disease in multiple myeloma. However, previous studies have found variable rates of V(D)J sequence identification at baseline, which could limit tracking. Here, we aimed to define the factors influencing the identification of clonal V(D)J sequences. Bone marrow mononuclear cells from 177 myeloma patients underwent V(D)J sequencing by the LymphoTrack assays (Invivoscribe). As a molecular control for tumor cell content, we sequenced the samples using our in-house myeloma panel myTYPE. V(D)J sequence clonality was identified in 81% of samples overall, as compared with 95% in samples where tumor-derived DNA was detectable by myTYPE. Clonality was detected more frequently in patients with lambda-restricted disease, mainly because of increased detection of kappa gene rearrangements. Finally, we describe how the tumor cell content of bone marrow aspirates decrease gradually in sequential pulls because of hemodilution: From the initial pull used for aspirate smear, to the final pull that is commonly used for research. In conclusion, baseline clonality detection rates of 95% or higher are feasible in multiple myeloma. Optimal performance depends on the use of good quality aspirates and/or subsequent tumor cell enrichment.

Loss of plasmacytoid dendritic cell differentiation is highly predictive for post-induction measurable residual disease and inferior outcomes in acute myeloid leukemia

Measurable residual disease is associated with inferior outcomes in patients with acute myeloid leukemia (AML). Measurable residual disease monitoring enhances risk stratification and may guide therapeutic intervention. The European LeukemiaNet working party recently came to a consensus recommendation incorporating leukemia associated immunophenotype-based different from normal approach by multi-color flow cytometry for measurable residual disease evaluation. However, the analytical approach is highly expertise-dependent and difficult to standardize. Here we demonstrate that loss of plasmacytoid dendritic cell differentiation after 7+3 induction in AML is highly specific for measurable residual disease positivity (specificity 97.4%) in a uniformly treated patient cohort. Moreover, loss of plasmacytoid dendritic cell differentiation as determined by a blast-to-plasmacytoid dendritic cell ratio >10 was strongly associated with inferior overall and relapse-free survival (RFS) [Hazard ratio 2.79, 95% confidence interval (95%CI): 0.98-7.97; P=0.077) and 3.83 (95%CI: 1.51-9.74; P=0.007), respectively), which is similar in magnitude to measurable residual disease positivity. Importantly, measurable residual disease positive patients who reconstituted plasmacytoid dendritic cell differentiation (blast/ plasmacytoid dendritic cell ratio <10) showed a higher rate of measurable residual disease clearance at later pre-transplant time points compared to patients with loss of plasmacytoid dendritic cell differentiation (blast/ plasmacytoid dendritic cell ratio <10) (6 of 12, 50% vs. 2 of 18, 11%; P=0.03). Furthermore pre-transplant plasmacytoid dendritic cell recovery was associated with superior outcome in measurable residual disease positive patients. Our study provides a novel, simple, broadly applicable, and quantitative multi-color flow cytometry approach to risk stratification in AML.

Predictive factors of fatal bleeding in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is associated with a profound coagulopathy. Based on retrospective assessments, several potential risk factors for hemorrhagic morbidity and mortality have emerged. Several studies have shown elevated white blood cell (WBC) count at presentation to be a robust predictor of bleeding events. Other clinical and laboratory parameters have been evaluated with variable association with hemorrhagic morbidity or mortality. These include ECOG performance status, age, morphological subtype, platelet count, peripheral blood blast count, ethnicity, body mass index, prothrombin time, activated partial thromboplastin time, lactate dehydrogenase, d-dimers, creatinine and fibrinogen levels. Unfortunately, most of those assessments were based on a small patient sample and the results have been at times contradictory in terms of which parameters are independent predictors. More recently, two large retrospective studies have reported on the issue. They included data from several international trials of chemotherapy for APL, one on adults and the other focused on the pediatric population. Importantly, both analyses found that WBC count at presentation is the main predictor of early hemorrhagic death and early thrombo-hemorrhagic death, respectively. Much remains to be done if the rate of induction mortality in APL is going to be reduced significantly. One approach would be to incorporate the known risk factors for early hemorrhagic death into a risk stratification system and devise personalized transfusion interventions to meet an individual patient's risk, which could be evaluated in future randomized trials.

A Bilayered Poly (Lactic-Co-Glycolic Acid) Scaffold Provides Differential Cues for the Differentiation of Dental Pulp Stem Cells

IMPACT STATEMENT

In this article we used an FDA-approved biodegradable biomaterial, poly (lactic-co-glycolic acid) (PLGA 75:25) to generate a bilayered scaffold with the capacity to induce differential, layer-specific dentinogenic differentiation of dental pulp stem cells (DPSCs) in vitro. We surmise that such a scaffold can be used in conjunction with current regenerative endodontic procedures to help regenerating a physiologic dentin-pulp complex in vivo. We hypothesize that our scaffold in conjunction with DPSCs will advance current regenerative endodontics by restoring dentin and initiating the innervation and revascularization of the pulp.

Autologous CD19-Targeted CAR T Cells in Patients with Residual CLL following Initial Purine Analog-Based Therapy

Patients with residual chronic lymphocytic leukemia (CLL) following initial purine analog-based chemoimmunotherapy exhibit a shorter duration of response and may benefit from novel therapeutic strategies. We and others have previously described the safety and efficacy of autologous T cells modified to express anti-CD19 chimeric antigen receptors (CARs) in patients with relapsed or refractory B cell acute lymphoblastic leukemia and CLL. Here we report the use of CD19-targeted CAR T cells incorporating the intracellular signaling domain of CD28 (19-28z) as a consolidative therapy in 8 patients with residual CLL following first-line chemoimmunotherapy with pentostatin, cyclophosphamide, and rituximab. Outpatients received low-dose conditioning therapy with cyclophosphamide (600 mg/m²), followed by escalating doses of 3 × 10⁶, 1 × 10⁷, or 3 × 10⁷ 19-28z CAR T cells/kg. An objective response was observed in 3 of 8 patients (38%), with a clinically complete response lasting more than 28 months observed in two patients. Self-limited fevers were observed post-CAR T cell infusion in 4 patients, contemporaneous with elevations in interleukin-6 (IL-6), IL-10, IL-2, and TGF-α. None developed severe cytokine release syndrome or neurotoxicity. CAR T cells were detectable post-infusion in 4 patients, with a longest observed persistence of 48 days by qPCR. Further strategies to enhance CAR T cell efficacy in CLL are under investigation.