Background: Transplant-associated thrombotic microangiopathy (TA-TMA) is a serious and potentially life-threatening complication after allogeneic hematopoietic cell transplantation (alloHCT). Multiple sets of clinical diagnostic criteria for TA-TMA have been developed in adult and pediatric settings based on single-institution chart review or expert panels, but none have been rigorously evaluated across multiple centers to assess validity or reproducibility. The TA-TMA Working Group is conducting a multi-national, multi-center, retrospective study to identify and confirm potential adult and pediatric cases of TA-TMA. The aim of creating a large cohort of adjudicated TA-TMA cases is to better understand the incidence, risk factors, clinical outcomes, and healthcare resource utilization (HRU) associated with this condition. Aims: To describe the multiple-adjudication methodology employed to confirm diagnosis of TA-TMA across adult and pediatric transplant centers. Methods: Twelve US and EU centers retrospectively screened medical records of patients who received alloHCT between 2015 and 2017 using 5 criteria: schistocytosis (>2 per high-power field); LDH level above ULN; doubling of baseline creatinine; platelet refractoriness (50% decrease in platelet count and/or platelet count less than individual center’s transfusion threshold x 4 days despite transfusions); and decreased haptoglobin. Cases meeting ≥3 criteria within a 10-day period during the first 12 months after alloHCT were considered potential TA-TMA and were further evaluated by 2 clinicians from each transplant center. Patients who had a positive biopsy, were diagnosed with TA-TMA or aHUS, or had received eculizumab following alloHCT were considered to have definite TA-TMA. Of all positive cases determined by local adjudications, 30% will be randomly selected for central adjudication by independent adult and pediatric adjudication committees. Central adjudicators have access to relevant laboratory and radiologic data. In cases with 2 discordant decisions, a third central adjudicator will be assigned to break the tie. In cases of 3 discordant decisions regarding the diagnosis of TA-TMA, the case will be forwarded for discussion led by the central adjudication chair. All cases determined as positive TA-TMA after local and central adjudication will be aggregated and analyzed to evaluate clinical outcomes, risk factors for TA-TMA, disease course, survival and non-relapse mortality, and HRU. Results: As of March 1, 2022, 3,732 cases have been screened at 11 transplant centers and 836 were considered potential TA-TMA that met ≥3 criteria. To date, local adjudication at 8 centers determined 179 cases were positive TA-TMA. Due to variations in laboratory standards at different centers, a challenge encountered in this study was harmonization of screening criteria. For example, labs at several centers did not quantify number of schistocytes as part of their CBC, which restricted screening of potential TA-TMA cases to 4 criteria, leading to some cases being categorized as “unknown.” These outcomes highlight the differences in assessing TA-TMA at multiple centers. Summary/Conclusion: This is the first multi-center comprehensive retrospective study to evaluate TA-TMA with a formalized process for independent local and central adjudication to verify TA-TMA diagnosis. The large cohort of TA-TMA cases identified in this study should enable validation of current and future diagnostic criteria, improve our understanding of prognostic/risk factors, and enhance awareness of this disease.

Donor type, in addition to transplantation in chronic phase and myeloablative conditioning, influence transplant survival for patients with advanced chronic myeloid leukemia in the era of tyrosine kinase inhibitors

This study aims to provide a detailed analysis of allogeneic stem cell transplantation (allo-SCT) outcomes in a large T-cell acute lymphoblastic leukemia (T-ALL) cohort with a specific emphasis on the effects of pre-transplant minimal residual disease (MRD) and disease subtype, including the aggressive early-thymic precursor (ETP) subtype. Data from 102 allo-SCT patients with a diagnosis of T-ALL from three centers were retrospectively analyzed. Patients were grouped into four T-ALL subtypes: ETP, early, cortical and mature. At 3 years, overall survival (OS), PFS, non-relapse mortality and cumulative incidence (CI) progression were 35, 33, 11 and 55%, respectively. Patients transplanted in first complete remission (CR1) had a 3-year OS of 62% versus those transplanted in CR2 or greater (24%) (hazards ratio 1.6, P=0.2). Patients with MRD positivity at the time of transplant had significantly higher rates of progression compared with those with MRD negativity (76 vs 34%, hazards ratio 2.8, P=0.006). There was no difference in OS, PFS or cumulative incidence (CI) progression between disease subtypes, including ETP (n=16). ETP patients transplanted in CR1 (n=10) had OS of 47%, comparable to other disease subtypes, suggesting that allo-SCT can overcome the poor prognosis associated with ETP. MRD status at transplant was highly predictive of disease relapse, suggesting novel therapies are necessary to improve transplant outcomes.

PR1, an HLA-A2-restricted peptide derived from both proteinase 3 and neutrophil elastase, is recognized on myeloid leukemia cells by cytotoxic T lymphocytes (CTLs) that preferentially kill leukemia and contribute to cytogenetic remission. To evaluate safety, immunogenicity and clinical activity of PR1 vaccination, a phase I/II trial was conducted. Sixty-six HLA-A2+ patients with acute myeloid leukemia (AML: 42), chronic myeloid leukemia (CML: 13) or myelodysplastic syndrome (MDS: 11) received three to six PR1 peptide vaccinations, administered subcutaneously every 3 weeks at dose levels of 0.25, 0.5 or 1.0 mg. Patients were randomized to the three dose levels after establishing the safety of the highest dose level. Primary end points were safety and immune response, assessed by doubling of PR1/HLA-A2 tetramer-specific CTL, and the secondary end point was clinical response. Immune responses were noted in 35 of 66 (53%) patients. Of the 53 evaluable patients with active disease, 12 (24%) had objective clinical responses (complete: 8; partial: 1 and hematological improvement: 3). PR1-specific immune response was seen in 9 of 25 clinical responders versus 3 of 28 clinical non-responders (P= 0.03). In conclusion, PR1 peptide vaccine induces specific immunity that correlates with clinical responses, including molecular remission, in AML, CML and MDS patients.

Allogeneic hematopoietic cell transplantation (HCT) was originally developed to allow delivery of myeloablative doses of chemotherapy and radiotherapy. With better understanding of disease pathophysiology, the graft vs malignancy (GVM) effect of allogeneic hematopoietic transplantation and toxicities associated with myeloablative conditioning (MAC) regimens, the focus shifted to developing less toxic conditioning regimens to reduce treatment-related morbidity without compromising survival. Although HCT with MAC is preferred to reduced intensity conditioning (RIC) for most patients ⩽60 years with AML/myelodysplastic syndrome and ALL, RIC and nonmyeloablative (NMA) regimens allow HCT for many otherwise ineligible patients. Reduced intensity preparative regimens have produced high rates of PFS for diagnoses, which are highly sensitive to GVM. Relapse of the malignancy is the major cause of treatment failure with RIC/NMA HCT. Incorporation of novel agents like bortezomib or lenalidomide, addition of cellular immunotherapy and use of targeted radiation therapies could further improve outcome. In this review, we discuss commonly used RIC/NMA regimens and promising novel regimens.

The B‐cell receptor signaling pathway, which is critical to the development and maturation of normal B‐cells, is emerging as an attractive therapeutic target in B‐cell malignancies. Ibrutinib is a potent irreversible inhibitor of Bruton's tyrosine kinase (Btk), a key kinase important for signal transduction in the B‐cell receptor (BCR) pathway. In preclinical studies, ibrutinib potently bound to Btk, inhibited BCR signaling, and decreased tumor cell proliferation and survival in many B‐cell malignancy models. Excellent safety and efficacy data in clinical trials have led to US Food and Drug Administration (FDA) approval of ibrutinib for previously treated mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL), as well as CLL with 17p deletion. Ongoing clinical studies have also demonstrated great potency of ibrutinib in treating other types of non‐Hodgkin's lymphoma (NHL), including diffuse large B‐cell lymphoma (DLBCL), follicular lymphoma (FL), and Waldenström's macroglobulinemia (WM). Combination of ibrutinib with chemoimmunotherapy and other promising novel agents in B‐cell malignancy therapy has also been under clinical investigation.

BACKGROUND:Although ibrutinib is highly effective in patients with relapsed/refractory mantle cell lymphoma (MCL), a substantial proportion of patients have resistant disease. The subsequent outcomes of such patients are unknown.PATIENTS AND METHODS:We carried out a retrospective review of all patients with MCL treated with ibrutinib at MD Anderson Cancer Center between January 2011 and January 2014 using pharmacy and clinical databases. Patients who had discontinued ibrutinib for any reason were included in the study.RESULTS:We identified 42 patients with MCL who discontinued therapy due to disease progression on treatment (n = 28), toxicity (n = 6), elective stem-cell transplant in remission (n = 4) or withdrawn consent (n = 4). The median age was 69 years, 35 (83%) were male; the median number of prior treatments was 2 (range 1-8) and the median time from initial diagnosis of MCL to commencing ibrutinib was 3.0 (range 0.5-15.5) years. Patients had received a median of 6.5 (range 1-43) cycles of ibrutinib. Among 31 patients who experienced disease progression following ibrutinib and underwent salvage therapy, the overall and complete response rates were 32% and 19%, respectively. After a median follow-up of 10.7 (range 2.4-38.9) months from discontinuation of ibrutinib, the median overall survival (OS) among patients with disease progression was 8.4 months. By univariate analysis, elevated serum lactate dehydrogenase at progression was associated with inferior OS.CONCLUSION:The outcome of patients with MCL who experience disease progression following ibrutinib therapy is poor, with both low response rates to salvage therapy and short duration of responses. Further studies to better understand and overcome ibrutinib resistance are urgently needed.

Loss of heterozygosity (LOH) has been shown to be associated with leukemia relapse after haploidentical transplantation. Whether such changes are an important cause of relapse after HLA-matched transplantation remains unclear. We retrospectively HLA-typed leukemic blasts for 71 patients with AML/myelodysplastic syndrome obtained from stored samples, and the results were compared with those obtained at diagnosis and/or before the transplant. No LOH or any other changes in HLA Ag were found in any of the samples tested post transplant as compared with pretransplant specimens. One patient had LOH in HLA class I Ag (HLA-A,-B and -C); however, these changes were present in the pretransplant sample indicating that they occurred before the transplant. We concluded that, in contrast with haploidentical transplantation, HLA loss does not have a major role as a mechanism of relapse after allogeneic transplantation with a closely HLA-matched donor.

Abstract Introduction While high dose chemotherapy and autologous hematopoietic stem cell transplantation (auto-HCT) is an accepted part of up front therapy for patients with multiple myeloma (MM), the role of this treatment modality for relapsed patients is still evolving. In light of data suggesting safety and synergy in combining novel therapeutics with traditional cytotoxic chemotherapy, we hypothesized that lenalidomide could be safely combined with high dose melphalan in the salvage auto-HCT setting and yield a meaningful duration of disease control. Methods We conducted a phase I/II study of lenalidomide and high dose melphalan + auto-HCT. MM patients with relapsed or progressive disease were treated with 7 days of oral lenalidomide (doses of 25, 50, 75 or 100 mg daily for the 7 days) on days (-8) to (-2). High dose melphalan (total of 200 mg/m2) was administered as 100 mg/m2 IV on days (-3) and (-2) followed by auto-HCT on day 0. The Eff-Tox method of Thall, Cook, and Estey was used for dose escalation with cohorts of 3 to maximize the trade-off between efficacy and toxicity, defined as CR at day 90 and regimen-related death, graft failure, or select grade 3+ events within 30 days after transplant, respectively. Kaplan-Meier method was used to estimate progression-free survival (PFS) and overall survival (OS) and the log-rank test was used to assess univariate differences between dose levels. Bayesian logistic regression and survival time models were used for multivariable analyses, with posterior probabilities greater than 0.95 or less than 0.05 considered significant. Initial results after 12.3 months of follow-up were published in 2015; we now present an update with 39.8 months of follow-up. Results 57 patients were enrolled, of which 18 (32%) had received a prior auto-HCT. A total of 3, 5, 24 and 25 patients received 25, 50, 75 and 100 mg of lenalidomide, respectively. Median age at auto-HCT was 60 (34-72) years. Median prior lines of treatment were 3 (1-11). Twenty-two patients (39%) were lenalidomide-refractory at study entry. Patient characteristics did not differ significantly between the lenalidomide dose levels. In total, only 2 dose-limiting toxicities were seen, both at dose level 75 mg. Two patients died of nonrelapse causes (viral infection 1, cardiac failure 1) for a treatment-related mortality of 4%. Median time to both neutrophil and platelet engraftment was 11 days. One patient developed a second primary malignancy (squamous cell cancer of the skin). 63% received maintenance therapy, (54% lenalidomide-based). By day +90, 8 patients (14%) had achieved a complete response (CR), 17 (30%) a very good partial response (VGPR), and 17 (30%) a partial response (PR), with no significant differences in response rates among the 4 lenalidomide dose levels. Best responses were PR: 26%, VGPR: 18%, near CR: 18%, CR: 7%, stringent CR: 23% for a ≥VGPR rate of 66. 23% achieved bone marrow minimal residual disease negativity by flow cytometry. Median time to achieve best response was 92 days (range: 16-732). One patient (2%) had progressive disease and 3 patients (5%) achieved only stable disease. Multivariable Bayesian logistic regression revealed that high-risk cytogenetics, (deletion 13q, t(4:14) or del 17p) by conventional cytogenetics or (t(4:14), t(14:16) or del17p by fluorescent in-situ hybridization), bone marrow disease burden and number of prior lines of treatment were each significantly associated with a lower probability of reaching CR by day 90. With a median follow up of 39.8 months (range: 0.5- 66.9), median PFS was 17.1 months (95% CI: 10.8 - 23.0, Figure 1) and median OS was 48.0 months (95% CI: 22.6 months, not estimated, Figure 2). There was no significant effect of dose level on PFS or OS. Multivariable Bayesian survival time models found high-risk cytogenetics to be significantly harmful to both OS and PFS. In addition, degree of plasma cell infiltration of bone marrow before auto-HCT was significantly harmful to PFS. Conclusion: Lenalidomide up to 100 mg PO daily x 7 can be safely combined with high dose melphalan and auto-HCT. Longer follow-up demonstrates PFS and OS as comparable to other salvage treatments for MM, suggesting that this regime can be applied as a part of the sequence of therapies for these patients. Figure 1 PFS of 17.1 months (95% CI: 10.8 - 23.0; N=57, Events=48) Figure 1. PFS of 17.1 months (95% CI: 10.8 - 23.0; N=57, Events=48) Figure 2 OS of 48.0 months (95% CI: 22.6 months, not estimated; N=57, Deaths=28) Figure 2. OS of 48.0 months (95% CI: 22.6 months, not estimated; N=57, Deaths=28) Disclosures Orlowski: Takeda Pharmaceuticals: Research Funding. Champlin:Intrexon: Equity Ownership, Patents & Royalties; Ziopharm Oncology: Equity Ownership, Patents & Royalties.

BACKGROUND:Hematopoietic stem cell transplant (HCT) recipients are more susceptible to infections from vaccine-preventable diseases than the general population. Despite the development of international consensus guidelines addressing immunization after HCT, studies have shown that deviations from recommended immunization practices commonly occur.METHODS:An anonymous survey aimed at determining awareness of the guidelines and attitudes toward vaccination was distributed to our HCT clinicians. In parallel, we retrospectively evaluated patients' characteristics and post-HCT vaccine administration practices from 2010 to 2013.RESULTS:The majority of survey respondents (96%) were familiar with post-HCT vaccination protocols. Seventy-four percent of respondents reported that influenza vaccines were given to >70% of their patients, and 41% stated that they prescribed live vaccines to eligible patients. However, our pharmacy database review revealed that 38% of patients received the first series of vaccinations by the recommended 6 months post HCT, and 60% received them by 1 year after HCT. Most patients who had their vaccines withheld had relapsed disease or were undergoing treatment for graft-versus-host disease. Furthermore, we identified lower immunization rates in non-English speaking individuals, African-Americans, and Hispanic patients.CONCLUSIONS:Survey respondents reported being aware of current guidelines; however, adherence to the recommendations varied, likely connected to conflicting data on vaccine effectiveness and a lack of clear recommendations in complex clinical scenarios. Similar to the general population, patient barriers also could have contributed to lower vaccination rates in some cases. To decrease the large gap between the post-HCT vaccination guidelines and clinical practice, further studies on vaccine effectiveness and specific populations are warranted.

Manufacturing Cell Therapy products for either hematopoietic or immune reconstitution requires mononuclear cell (MNC) enrichment to remove red blood cells, granulocytes and non-viable cells and is achieved by ficol density gradient separation. The manual method that is used by most laboratories is an open processing method. Biosafe offers an automated closed system (Sepax 2) for MNC enrichment. The two methods have been compared here by enriching MNCs from 20 cryopreserved cord blood units (CBU). For transplant or immune reconstitution, a fresh cord is never used and hence cryopreserved CBU were used for this study. The viability of total nucleated cells (TNC) and CD34+ cells after enrichment by both methods was the same. Between the two methods, there was no significant difference in recovery of total lymphocytes (37% by manual vs. 39% by Sepax; P=0.66), B Cells (30% by manual vs. 36% by Sepax; P=0.14), T cells (29% by manual vs. 27% by Sepax; P=0.44), and monocytes (39% by manual vs. 46% by Sepax; P=0.20). However, the Sepax method gave a significantly higher recovery of TNC (22% by manual vs. 28% by Sepax; P=0.007), CD34+ (24% by manual vs. 50% by Sepax; P<0.0001) and NK Cells (14% by manual vs. 29% by Sepax; P<0.0001) and total colony forming units (0.9×106 by manual vs. 1.6×106 by Sepax; P=0.016). The manual method was better in reducing the hematocrit (97% by manual vs. 80% by Sepax; P<0.0001), platelets (96% by manual vs. 87% by Sepax; P<0.0001) and granulocytes (89% by manual vs. 82% by Sepax; P=0.0005). The Sepax MNC enrichment method offers an advantage over the manual method in terms of being a closed system and better cell recoveries.

Disseminated adenoviral infection (AI) is associated with profound immunosuppression and poor outcome after allogeneic hematopoietic SCT (allo-HSCT). A better understanding of AI in allo-HSCT recipients can serve as a basis to develop more effective management strategies. We evaluated all adult patients who received allo-HSCT at MD Anderson Cancer Center between 1999 and 2008. Among the 2879 allo-HSCT patients, 73 (2.5%) were diagnosed with AI. Enteritis (26%) and pneumonia (24%) were the most common clinical manifestations; pneumonia was the most common cause of adenovirus-associated death. A multivariable Bayesian logistic regression showed that when the joint effects of all covariates were accounted for, cord blood transplant, absolute lymphocyte count (ALC) ⩽200/mm3 and male gender were associated with a higher probability of disseminated AI. The OS was significantly worse for patients with AI that was disseminated rather than localized (median of 5 months vs median of 28 months, P<0.001) and for patients with ALC ⩽200/mm3 (P<0.001). Disseminated AI, in patients who received allo-HSCT, is a significant cause of morbidity and mortality. Strategies for early diagnosis and intervention are essential, especially for high-risk patients.

We investigated the safety and early disease control data for i.v. busulfan (Bu) in combination with clofarabine (Clo) in patients with acute lymphoblastic leukemia undergoing allogeneic hematopoietic stem cell transplantation (SCT). Fifty-one patients (median age, 36 years; range, 20-64 years) received a matched sibling (n = 24), syngeneic (n = 2), or matched unrelated donor transplant (n = 25) for acute lymphoblastic leukemia in first complete remission (n = 30), second complete remission (n = 13), or active disease (n = 8). More than one-half of the patients had a high-risk cytogenetic profile, as defined by the presence of t(9;22) (n = 17), t(4;11) (n = 3), or complex cytogenetics (n = 7). Clo 40 mg/m(2) was given once daily, with each dose followed by pharmacokinetically dosed Bu infused over 3 hours daily for 4 days, followed by hematopoietic SCT 2 days later. The Bu dose was based on drug clearance, as determined by the patient's response to a 32-mg/m(2) Bu test dose given 48 hours before the high-dose regimen. The target daily area under the receiver-operating characteristic curve was 5500 μM/min for patients age <60 years and 4000 μM/min for those age ≥60 years. The regimen was well tolerated, with a 100-day nonrelapse mortality rate of 6%. With a median follow-up of 14 months among surviving patients (range, 6-28 months), the 1-year overall survival, disease-free survival, and nonrelapse mortality rates were 67% (95% confidence interval [CI], 55%-83%), 54% (95% CI, 41%-71%), and 32% (95% CI, 16%-45%), respectively. For patients undergoing SCT in first remission, these respective rates were 74%, 64%, and 25%. Our data indicate that the combination of Clo and Bu provides effective disease control while maintaining a favorable safety profile.