ALBERT

Description: In acute myeloid leukemia (AML), TP53 mutations and dysregulation of wild-type p53 is common and supports an MDM2 antagonist as a therapy. RO6839921 is an inactive pegylated prodrug of the oral MDM2 antagonist idasanutlin (active principle [AP]) that allows for IV administration. This phase 1 monotherapy study evaluated the safety, pharmacokinetics, and pharmacodynamics of RO6839921 in patients with AML. Primary objectives identified dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD). Secondary objectives assessed pharmacokinetic, pharmacodynamic, and antileukemic activity. A total of 26 patients received 120–300 mg AP of idasanutlin. The MTD was 200 mg, with DLTs at 250 (2/8 patients) and 300 mg (2/5). Treatment–related adverse events in 〉20% of patients were diarrhea, nausea, vomiting, decreased appetite, and fatigue. Six deaths (23.1%) occurred, all unrelated to treatment. Pharmacokinetics showed rapid and near-complete conversion of the prodrug to AP and dose-proportional exposure across doses. Variability ranged from 30%–47% (22%–54% for idasanutlin). TP53 was 21 (87.5%) wild-type and 3 mutant (12.5%). The composite response rate (complete remission [CR], CR with incomplete hematologic recovery/morphological leukemia-free state [CRi/MLFS], or CR without platelet recovery [CRp]) was 7.7%. Antileukemic activity (CR, CRi/MLFS, partial response, hematologic improvement/stable disease) was observed in 11 patients (disease control rate, 42%): 10/11 were TP53 wild-type; 1 had no sample. p53 activation was demonstrated by MIC-1 induction and was associated with AP exposure. There was not sufficient differentiation or improvement in the biologic or safety profile compared with oral idasanutlin to support continued development of RO6839921. NCT02098967.

Description: Despite recent advancements, approximately 50% of patients with acute myeloid leukemia (AML) do not respond to induction therapy (primary induction failure, PIF) or relapse after

Description: Preclinical studies previously reported by our group at ASH suggest that treatment with granulocyte-stimulating factor (G-CSF) may provide a potent and well-tolerated method to disrupt the 'leukemia cell niche'. Specifically, our data show that G-CSF treatment in mice reprograms bone marrow stromal cells, markedly inhibiting their expression of key chemokines/cytokines that support B lymphopoiesis, including stromal derived factor-1 (SDF-1/ CXCL12), interleukin-6 (IL-6), insulin-like growth factor-1 (IGF-1), and interleukin-7 (IL-7). These changes in the bone marrow microenvironment result in a more than 10-fold decrease in B cells in the bone marrow, including early B cell precursors. Preliminary studies in humans suggest that G-CSF has a similar effect on the bone marrow microenvironment in healthy subjects. Since these B trophic factors also have been implicated in the maintenance of B cell acute lymphoblastic leukemia (ALL) cells, we hypothesize that G-CSF treatment in patients with acute lymphoblastic leukemia (ALL) will generate a 'hostile' bone marrow microenvironment for ALL cells, depriving them of key support signals and rendering them more sensitive to cytotoxic therapy. Herein, we specifically test whether niche disruption with G-CSF augments inotuzumab-mediated ALL cell clearance. Inotuzumab ozogamicin (Pfizer) is a CD22-calicheamicin antibody-drug conjugate. Initial clinical trials have documented activity of inotuzumab in B-ALL, with an overall response rate of 57% in relapsed or refractory B-ALL. To test this hypothesis, we developed a xenotransplantation model of human ALL using the human B-ALL G2 cell line, which expresses moderate levels of CD22. G2 cells transduced with a GFP-click beetle red luciferase retroviral construct to allow for in vivo bioluminescent imaging were injected intravenously into NOD/SCID/γc-/- (NSG) mice. The G2 cells preferentially home to the bone marrow but eventually metastasize to other organs, including the brain. Four cohorts of mice were studied (n = 9-21, each), including: 1) G2 ALL cells alone; 2) inotuzumab alone (single injection of 80 µg/kg, IP); 3) G-CSF alone (100 µg/kg/day for 14 days by continuous subcutaneous infusion); or 4) G-CSF plus inotuzumab (G-CSF was started four days prior to inotuzumab). Treatment with inotuzumab increased median survival from 25.5 days to 41 days (P 〈 0.0001). G-CSF alone had no effect on survival. However, combination of G-CSF plus inotuzumab further increased survival to 49 days (P = 0.01 compared with inotuzumab alone). G-CSF also improved survival in mice given two doses of inotuzumab (each 80 µg/kg, IP) 10 days apart. Bioluminescent imaging revealed that, in several of the mice in the G-CSF plus inotuzumab group, the bioluminescent signal was predominantly localized to the brain, with little or no signal in bone. These data are consistent with the possibility that inotuzumab may have limited penetration into the brain. Thus, the positive effect of combination G-CSF plus inotuzumab on survival may be limited by CNS disease in this model. Indeed, the addition of G-CSF to inotuzumab decreased the bioluminescent signal in bone regions on day 21 after inotuzumab by approximately 10-fold (Figure 1, P 〈 0.001). Collectively, these data suggest that G-CSF significantly augments inotuzumab-mediated ALL clearance from the bone marrow. G-CSF may provide a non-toxic and cost-effective approach to increase durable response rates to inotuzumab (and other types of immunotherapy) in patients with B ALL. Figure 1 Figure 1. Disclosures Link: Pfizer: provided Inotuzumab for preclinical studies Other.

Description: Background: Adult acute myeloid leukemia (AML) patients with high-risk cytogenetics have a significantly worse survival compared to similarly treated intermediate- or favorable-risk patients. Although prior studies suggest better outcome in high-risk AML patients in first complete remission (CR1) who undergo allogeneic hematopoietic cell transplantation (HCT) compared with consolidation chemotherapy, only 40% of patients proceed to HCT. The lack of a matched sibling donor (available in about 33%) should not be a barrier to HCT since alternative donors are available for the large majority of high-risk AMLpatients and recent data suggest outcomes after allogeneic HCT from fully matched unrelated donors are similar to those following matched related donor transplantation. We sought to determine if a prospective organized effort could rapidly identify alternative donors to improve the historical 40% allogeneic HCT rate in high-risk CR1 AML patients ≤ age 61. Secondly, we hypothesized that transplanting significantly more adults with high-risk AML in CR1 would lead to an improved outcome compared with the historical relapse-free survival (RFS) of 22%. Patients and Methods: Adult patients between ages 18 and 60 years with untreated AML were randomized to receive induction therapy with standard cytarabine plus daunorubicin (7+3; n=261), idarubicin with high-dose cytarabine (IA; n=261), or IA with vorinostat (IA+V; n=216). Conventional cytogenetics were obtained at time of enrollment and used to determine risk classification by standard criteria. All patients with high-risk cytogenetics underwent expedited HLA-typing. High-risk patientswere encouraged tobe referred for consultation with a transplant team with the goal of conducting an allogeneic HCT in CR1. Results: Of 738 eligible patients (median age, 49 years; range, 18-60), 159 (22%) had high-risk cytogenetics, of whom 60 (38%), 61 (38%), and 38 (24%) received induction with 7+3, IA, or IA+V, respectively. A total of 107 of the 159 high-risk patients achieved CR/CRi (67%). HCT was performed in 317 of all 738 patients (43%) and 68 (64%) of the high-risk patients received a transplant in CR1 (p

Description: Background Binding of E-selectin (E-sel) to sialyl Lex, the E-sel ligand, on the leukemic cell surface activates cell survival pathways and promotes chemotherapy resistance in AML. Higher expression of E-sel ligand is associated with relapse and poor survival. Uproleselan (GMI-1271), a novel E-selectin antagonist, disrupts cell survival pathway activation, enhances chemotherapy response and protects from toxicity such as mucositis with improved survival in vivo. Preclinical data support combination of uproleselan with chemotherapy improves response without additional toxicity. A phase 1/2 study (NCT02306291) of uproleselan added to chemotherapy (mitoxantrone, etoposide, cytarabine, MEC) in R/R AML showed promising outcomes at the recommended phase 2 dose (RP2D), including a CR/CRi rate of 41% and median OS of 8.8 m (95% CI 5.7-11.4). 11/16 (69%) evaluable patients were MRD negative (DeAngelo et al ASH 2018). Patients with sufficient expression of the appropriate E-selectin ligand (the target of the E-selectin inhibitor) exhibited higher CR/CRi rate and longer survival. Median OS for Leukemic blasts/E-sel ligand ≥10% vs leukemic blasts/E-sel ligand

Description: Abstract 44 CALGB (now part of the Alliance for Clinical Trials in Oncology) performed a non-randomized phase II study testing one year (yr) of investigational maintenance therapy with decitabine for newly diagnosed adult AML patients (pts) 1 × 109/L, platelets 〉75 × 109/L, and be within 90 days after day 1 of the final consolidation. Decitabine 20mg/m2 was given IV over 1 hour for 4–5 days, every 6 weeks, for 8 cycles. 546 pts enrolled with a median age of 48 yrs (range, 17–60) and median presenting white blood count (WBC) of 12.6 × 109/L (range, 0.3–380 × 109/L). 75% achieved CR (412/546). Reasons for CR pts not receiving maintenance were mainly early relapse, alloHCT in 1st CR, inadequate count recovery, and patient refusal (Blum et al. ASH 2011). 33% of CR pts (134/412) received investigational maintenance. Of these, 46 (34%) were favorable risk; among the remaining 88 pts, 73 were consolidated with autoHCT, and 15 received HiDAC-based consolidation. The median time from initial study registration to initiation of maintenance therapy was 6.3 months. Pts receiving decitabine had a median age of 45 yrs (range, 18–60) and presenting WBC of 13.5 × 109/L (range, 0.4–221 × 109/L). Treatment with decitabine maintenance was feasible and reasonably well tolerated; the primary toxicity was myelosuppression. Preplanned dose reduction criteria for neutropenia were met after the first 20 pts had been treated. After this early timepoint, all subsequent pts who had been consolidated with autoHCT received only 4 days of decitabine per cycle (HiDAC consolidated pts continued to receive 5 days per cycle). The median number of cycles of decitabine received was 7 (range, 1–8); 46% of pts (62/134) received all 8 cycles, and 75% completed at least 4 cycles. Reasons for discontinuation of decitabine before completing 8 cycles included relapse (28%, 38/134), pt refusal (13%), adverse events (4%), and others. In this selected cohort of pts who received post-CR maintenance with decitabine, 1-yr and 3-yr overall survival (OS) were 96% and 66%; 1-yr and 3-yr disease-free survival (DFS) were 80% and 53%. 1-yr “failure-free survival” calculated from the time of registration to decitabine was 68% (70% for favorable risk, 68% for others). These results are similar to the outcomes for comparable pts enrolled on our prior CALGB study 19808 who received identical chemotherapy for induction and consolidation and then were randomized to observation or maintenance with interleukin-2 (3-yr OS 61% and 68%, 3-yr DFS 45% and 56%, for observation and IL-2 respectively). Post-consolidation maintenance with decitabine appears to provide only modest, if any, benefit overall. Correlative studies for CALGB 10503 are ongoing, including investigations into the impact of decitabine in unique molecular and cytogenetic subsets of disease, the prognostic/predictive value of aberrant methylation and other molecular markers, and assessment of minimal residual disease. Supported by CA33601 and CA128377. Disclosures: No relevant conflicts of interest to declare.

Description: Background: Over the past two decades, peripheral blood stem cells (PBSC) have surpassed bone marrow as the preferred graft source for adult allogeneic transplantation due to its more rapid engraftment and potentially better graft-vs-tumor effects, and because PBSC collection is much less invasive for the donor. The optimal CD34+ PBSC dose is ≥ 4.0x106cells/kg, but doses ≥ 8.0x106cells/kg are suggested by some for reduced-intensity conditioning and haploidentical transplants. There is no established minimum CD34+ PBSC dose, but doses below 2.0x106cells/kg have been associated with a higher risk of engraftment delay and failure. There is significant inter-donor variability in the ability to mobilize PBSCs. Several factors have been identified as predictors of PBSC mobilization in healthy donors including: gender, age, weight, body mass index (BMI), and blood counts before and after mobilization. The impact of the donor’s comorbidities on mobilization is currently unknown. Patients/Methods: We performed retrospective chart review of 488 consecutive adult patients who underwent apheresis for allogeneic stem cell donation at Washington University School of Medicine from 2006 through 2013. Patients who received any collection regimen other than 10mcg/kg of G-CSF daily with 20 liters (+/-10%) apheresis on Day 5 were excluded. Patients who had undergone a previous apheresis for stem cell donation were excluded. Univariate analysis was performed to identify predictors of CD34+ PBSC collection in a single apheresis. Variables analyzed were: gender; age; weight; BMI; donor-to-recipient weight ratio; pre and post-mobilization blood counts (white blood count [WBC], hematocrit, platelets, neutrophils, lymphocytes, and monocytes); pre-mobilization glucose and triglyceride levels; post-mobilization peripheral blood (PB) CD34+count; and medical history significant for hypertension, hyperlipidemia, or diabetes mellitus. Subsequently, a linear regression multivariate analysis was performed with all variables found to be significant in the univariate analysis. 2-tailed tests for significance were used throughout the analysis. Results: 304 patients met the eligibility criteria for analysis. The median age was 53 years (range 18-76), 90% were Caucasian, and 50% were male. The median number of CD34+ cells collected was 7.4 x106/kg (range 0.8-27.1). 97% (295) collected ≥ 2.0x106 CD34+cells/kg, 81% (247) collected ≥ 4.0x106 CD34+cells/kg, and 44% (134) collected ≥ 8.0x106 CD34+ cells/kg. Post-mobilization PB CD34+ count (r= 0.841, p

Description: We sought to determine whether bexarotene can be combined with decitabine in elderly and relapsed AML patients. Both drugs have been shown to be well tolerated in acute myeloid leukemia (AML) patients as single agents, and these agents have non-overlapping mechanisms and side-effect profiles; bexarotene activates transcriptional effects of RXRA through hetero- and homodimers, while decitabine is thought to act through DNA hypomethylation. Furthermore, through Affymetrix expression array profiling of 111 AML patients and Nanostring analysis of 7 MDS and AML patients, we observed consistently elevated levels of RXRA relative to RARA, suggesting that a ligand specific for RXR may be more effective to induce AML differentiation than the RARA ligand ATRA. We treated 18 elderly (≥ 60 years old) or relapsed AML patients in 3+3 dose escalating bexarotene cohorts: 100 mg/m2/day, 200 mg/m2/day, 300 mg/m2/day. All patients were treated with decitabine 20 mg/m2IV on days 1-5 of 28 day cycles. All patients were monitored for hypertriglyceridemia and hypothyroidism, and treated accordingly. The average age was 73, the average performance status was 1, an adverse karyotype was observed in 9 patients, and 12 patients had relapsed after prior therapy. Only one patient experienced a dose limiting toxicity (grade 3 fatigue) and 8 patients were treated with the maximum dose (myelosuppression, infection, differentiation syndrome, hypertriglyceridemia, hyperlipidemia, hypothyroidism, nausea, weight loss and reversible electrolyte abnormalities were not considered dose limiting). The overall response rate was 22%: 1 patient achieved complete remission with incomplete count recovery (CRi) and 3 patients achieved blast reduction greater than 50% (partial response, PR). In addition, six patients achieved stable disease (SD). Patients with CRi, PR, or SD completed an average of 4.25 cycles, while other patients completed an average of 1.2 cycles. Of note, 3 patients successfully transitioned to allogeneic transplant following therapy (average age 68). We correlated ex vivo bexarotene sensitivity with clinical response. Bone marrow cells were collected on day 0 and day 3 of bexarotene therapy (during cycle 1, decitabine was administered on day 3 after bone marrow collection) and co-cultured with irradiated MS5 murine stromal cells for 72hrs with or without further bexarotene treatment. We used flow cytometry to compare CD11b expression in cells treated with and without bexarotene ex vivo, and compared expression between samples collected on day 0 vs day 3 (in vivo treatment). Bexarotene increased CD11b expression greater in the 4 responding patients vs non-responders (fold increase in CD11b: ex vivo average 2.1 ± 0.3 vs 1.1 ± 0.1 fold, p 〈 0.003; and in vivo 1.6 ± 0.3 vs 0.7 ± 0.2 fold, p 〈 0.03; increase in absolute percentage of CD11b+ cells: ex vivo average 24% ± 2.6% vs 0.7% ± 1%, p 〈 0.001; and in vivo 13.6% ± 4% vs -3.6% ± 2.2%, p 〈 0.002). Furthermore, all 4 responding patients demonstrated an equivalent or increased induction of CD11b when treated ex vivo with ATRA compared with bexarotene. These results show that bexarotene, a retinoid which selectively binds to and activates RXRs, but not RARs, can be safely combined with decitabine in relapsed and refractory AML patients. This combination leads to partial response in a subset of patients, is well tolerated, and can bridge elderly patients to allogeneic transplant. Because ex vivo bexarotene treatment identified all patients achieving a PR, further studies should focus on patients who display ex vivo sensitivity. Finally, the mechanism of RXRA-activated differentiation is likely to be through the RXRA/RARA heterodimer, as all 4 patients who responded to bexarotene also responded to ATRA when tested ex vivo. Disclosures: Welch: Eisai: Research Funding. Off Label Use: Bexarotene for the treatment of AML. Abboud:Ariad, Alexion, Novartis, Teva: Honoraria, Speakers Bureau. Stockerl-Goldstein:Celgene : Speakers Bureau; Millennium: Speakers Bureau.