ALBERT

Description: We retrospectively evaluated 18fluoro-2-deoxyglucose positron emission tomography (FDG-PET) scans in 172 patients with lymphoma and correlated results with pathologic diagnosis using the World Health Organization (WHO) classification system. In total, FDG-PET detected disease in at least one site in 161 patients (94%) and failed to detect disease in 11 patients (6%). The most frequent lymphoma diagnoses were diffuse large B-cell lymphoma (LBCL; n = 51), Hodgkin lymphoma (HL; n = 47), follicular lymphoma (FL; n = 42), marginal zone lymphoma (MZL; n = 12), mantle cell lymphoma (MCL; n = 7), and peripheral T-cell lymphoma (PTCL; n = 5). FDG-PET detected disease in 100% of patients with LBCL and MCL and in 98% of patients with HL and FL. In contrast, FDG-PET detected disease in only 67% of MZL and 40% of PTCL. Comparison with bone marrow biopsies showed that FDG-PET was not reliable for detection of bone marrow involvement in any lymphoma subtype.

Description: In vitro, bexarotene inhibits the proliferation of non-M3 AML cell lines and induces differentiation of leukemic blasts. Our previous phase I study in non-M3 AML showed evidence of leukemic response as manifested by reduction in bone marrow blast counts (15% response rate), improved platelet counts (41%) and improved neutrophil counts (26%). Based on these results, a phase II trial in non-M3 AML was initiated at the phase I MTD. In the current phase II trial, bexarotene (300mg/m2) was administered daily as monotherapy until disease progression or unacceptable side effects occurred. Fourteen patients have been enrolled: 8M/6F, median age 74 (range 20–83), 9 secondary AML (MDS or prior chemotherapy), 9 primary refractory or relapsed 〈 1 year after induction, 5 no prior induction chemotherapy, 5 requiring hydroxyurea at the time of enrollment for leukemic blast control, 4 prior allogeneic stem cell transplant, 12 blood transfusion dependent, 11 platelet transfusion dependent, and 8 neutropenic. Overall, no significant adverse events were noted. All patients received prophylactic antihyperlipidemic agents and achieved good lipid control. Two patients developed mild hypothyroidism related to bexarotene. Five patients were evaluable with bone marrow biopsy at 2 months: 1 50% reduction in absolute blasts, 1 SD and 3 PD. Similar to data from our prior phase I study, evidence of clinical activity was manifested as platelet count response in 1 patient and neutrophil increases attributable to bexarotene in 2 patients. When combining the results of our phase I experience (27 patients) with our phase II data (14 patients), there is a suggestion of increased activity in patients with 5q minus abnormalities with 4/7 (57%) benefiting (2 BM response, 4 neutrophil improvements and 1 platelet response). Conversely rates of clinical benefit were lower in patients with multiple (〉3) cytogenetic abnormalities (2/13), relapse after stem cell transplant (1/9) or requiring hydroxyurea for peripheral blast control at the time of study enrollment (0/10). Bexarotene is very well tolerated at the dose level studied. Early evidence for clinical activity has been seen as exemplified by improvement in platelet count, increased neutrophil counts and decreased bone marrow blasts. In summary, we conclude that bexarotene is an active agent in a subgroup of patients with AML. Study enrollment continues with amended inclusion criteria to focus on patients more likely to benefit from treatment.

Description: In vitro, bexarotene has been shown to inhibit the proliferation of non-M3 AML cell lines and induce differentiation of leukemic blasts. This phase I study was designed to evaluate the safety of escalating doses of bexarotene in patients with non-M3 AML. Bexarotene was administered orally daily until disease progression occurred. Prophylactic antihyperlipidemic agents were used in all patients. Six dose levels ranging from 100 to 400mg/m2 are planned. Dose escalation occurred in cohorts of 3–6 patients based on dose-limiting toxicity. Twenty patients have been enrolled in 5 dose cohorts (100–300mg/m2) with enrollment demographics: 13M/7F, median age 69 (range 51–82), 11 prior MDS, 8 primary refractory, median number of induction attempts 2, no prior induction chemotherapy 2, prior autologous stem cell transplant 4, 19 blood transfusion dependent, 13 platelet transfusion dependent, and 16 neutropenic. Consistent with reported toxicity, 2 patients developed hypothyroidism, 7 patients developed grade 2–4 hypertriglyceridemia and 1 patient developed grade 2 pancreatitis. Two patients developed a syndrome reminiscent of retinoic acid syndrome, consisting of dyspnea/hypoxia, pleural/pericardial effusions, weight gain/edema and dry cough in the setting of a rapidly rising neutrophil count. This syndrome resolved within 48 hours of stopping bexarotene and initiating steroids. No CR’s were noted, however significant evidence of drug activity were seen. Six patients showed evidence of neutrophil response (pretreatment median ANC 286/μL, range 28–1,037/μL, posttreatment ANC 3,150/μL, range 1,100–27,207/μL). Flow sorted peripheral blood neutrophils were collected from three of these patients and examined by FISH. Between 92–100% of purified neutrophils contained the patient’s leukemic cytogenetic abnormality suggesting differentiation of the leukemic blasts. Bone marrow blasts decreased to

Description: Introduction: Acute undifferentiated leukemia (AUL) is a rare type of acute leukemia that shows no evidence of differentiation along any lineage. Clinical, immunophenotypic and genetic data is limited: the largest study to date reported 16 AUL cases but did not use the current WHO classification and included limited genetic data on 5 cases (Ann Hematol 2013 92:747-758). Moreover, it is uncertain if AUL is biologically distinct from acute myeloid leukemia with minimal differentiation (AML MD), which also shows limited myeloid marker expression and has been reported to have a poor prognosis. Methods: A total of 95 cases (36 AUL cases 59 AML MD) were identified from pathology databases of eight academic institutions with available diagnostic flow cytometric data, cytogenetic findings, and clinical data by searching for diagnoses of "AUL" or "AML MD". Diagnosis of AUL required absence of any lineage-defining markers including MPO, CD19 and CD3. Using the WHO classification, diagnosis of AML with MD required expression of at least 2 myeloid markers (CD117, CD13 or CD33), absence of myeloid maturation (CD15) or monocytic markers (CD64, CD11b, lysozyme or non-specific esterase). Next generation sequencing with extensive mutational panel data was available in 78 cases. Outcome analysis for overall survival (OS) and relapse-free survival (RFS) and were performed using Kaplan Meier and log rank test for patients who received induction chemotherapy. Results: Based on cytogenetic abnormalities (N=27) or history of MDS (N=2), according to the 2016 WHO Classification, 28 cases (6 AUL and 22 AML MD) were re-classified as AML with myelodysplasia related changes (AML MRC). The remaining 30 AUL patients presented with similar age, blood counts, bone marrow cellularity, and blast percentage as the 37 AML MD patients (all p 〉 0.05). Comparison of immunophenotype in the two groups showed that AUL blasts had more frequent expression of TdT (p=0.0003) and lacked myeloid markers (CD117, CD13 or CD33 p0.05) were seen between these two groups. The frequency of abnormal karyotype was similar between AUL and AML MD (16/30 [53%] vs 15/37 [41%], respectively). The most common mutations identified in AUL were PHF6 (7/18), SRSF2 (7/18), RUNX1 (7/23), ASXL1 (6/23) and BCOR (5/16). Compared to AML MD, AUL cases were characterized by frequent mutations in PHF6 (7/18 vs 1/23, p=0.013) and SRSF2 (7/18 vs 2/22 p=0.028). Limiting AUL cases to only those with 1 myeloid marker or less also showed similar findings with more frequent mutations in PHF6 (7/16 vs 1/25, p=0.0031), SRSF2 (6/15 vs 3/26 p= 0.018) and trend towards higher BCOR frequency (5/15 vs 2/26, p=0.078) in AUL patients as compared to AML MD. RUNX1 mutation was seen in 7/23 AUL and 8/29 AML MD (p〉0.05). 19/30 AUL patients received induction chemotherapy (AML-type regimen in 18 cases and an ALL-type regimen in 1 case) and 15/30 achieved complete remission. In 10 AUL patients who relapsed, 9 showed identical immunophenotype and one case showed expression of CD13 and CD33. Outcome data in the subset of patients who received induction showed no difference in OS, RFS, or rates of complete remission between AUL and AML MD groups (p〉0.05). The 28 AML MRC cases that were originally classified as AUL or AML MD presented with lower WBC (p=0.026), more frequent abnormal karyotype (27/28) specifically complex karyotype (20/28 p=0.002), frequent TP53 mutations (p=0.0002) when compared to the AUL group. AML MRC patients showed worse overall OS (p=0.029) as compared with AUL patients and a trend toward worse outcome as compared with AML MD (p=0.068). Conclusions: In this largest series to date, AUL group shows distinct characteristics from AML MD, including more frequent PHF6 and SRSF2 mutations and expression of TdT. However, clinical outcome is similar between the two groups in patients treated with induction chemotherapy. Cases reclassified as AML-MRC had shorter survival compared to de novo AUL and trend towards worse outcome when compared to AML MD patients. These results suggest a genetic rationale for the separation of AUL as a distinct entity from AML MD and also support the WHO classification of cases with history of prior MDS and/or MDS-type karyotype findings as AML-MRC. Disclosures Garcia: Celgene: Consultancy.

Description: NF-κB and Notch signaling can be simultaneously activated in a variety of B-cell lymphomas. Patients with B-cell lymphoma occasionally develop clonally related myeloid tumors with poor prognosis. Whether concurrent activation of both pathways is sufficient to induce B-cell transformation and whether the signaling initiates B-myeloid conversion in a pathological context are largely unknown. Here, we provide genetic evidence that concurrent activation of NF-κB and Notch signaling in committed B cells is sufficient to induce B-cell lymphomatous transformation and primes common progenitor cells to convert to myeloid lineage through dedifferentiation, not transdifferentiation. Intriguingly, the converted myeloid cells can further transform, albeit at low frequency, into myeloid leukemia. Mechanistically, coactivation of NF-κB and Notch signaling endows committed B cells with the ability to self renew. Downregulation of BACH2, a lymphoma and myeloid gene suppressor, but not upregulation of CEBPα and/or downregulation of B-cell transcription factors, is an early event in both B-cell transformation and myeloid conversion. Interestingly, a DNA hypomethylating drug not only effectively eliminated the converted myeloid leukemia cells, but also restored the expression of green fluorescent protein, which had been lost in converted myeloid leukemia cells. Collectively, our results suggest that targeting NF-κB and Notch signaling will not only improve lymphoma treatment, but also prevent the lymphoma-to-myeloid tumor conversion. Importantly, DNA hypomethylating drugs might efficiently treat these converted myeloid neoplasms.

Description: Abstract 885 Although high clinical response rates to the FLT3 inhibitor quizartinib (AC220) among subjects with relapsed/refractory AML suggest a potential clinical breakthrough, there remains concern that few subjects achieved CR or PR by strict IWG response criteria. Prior reports describe terminal neutrophil differentiation of AML blasts during clinical response to AC220 (Sexuaer, et al. ASH 2011, #943), suggesting that traditional chemotherapy metrics may not prove relevant to measure FLT3 inhibitors' clinical activity. Here we characterize responses to AC220 from a recent Phase II clinical trial, based on histomorphologic, molecular, and cytogenetic analysis and independent of that study's modified IWG metrics. We describe at least two distinct types of morphologic responses to AC220 among the 21 subjects treated at our site on this single-arm trial. All subjects had AML that relapsed or was refractory to prior chemotherapy. Subjects received single agent AC220 daily at 90–200 mg and were evaluated by bone marrow aspiration and biopsy on treatment days 15 and 29 and then monthly until blasts were cleared from blood and marrow. 15 of 21 enrolled subjects were FLT3-ITD+; 6 were FLT3 wild type (WT). 14/16 subjects with circulating or extramedullary blasts at study entry showed complete morphologic elimination of these populations. 18/20 subjects with marrow blasts 〉20% at study entry reduced marrow blasts to

Description: The mechanisms that regulate the growth and survival of acute myeloid leukemia (AML) cells are largely unknown. We hypothesized that constitutive activation of phosphatidyl-inositide 3 kinase (PI3 kinase) could regulate survival in primary cells from patients with AML. Here we demonstrate that Akt, a critical substrate of PI3 kinase, is activated in AML blasts. In a short-term culture system, most AML patient samples showed a dose-dependent decrease in survival after incubation with the PI3 kinase inhibitor LY294002. This decrease in survival was partially due to the induction of apoptosis. Furthermore, we have shown that p70 S6 kinase and 4EBP-1, downstream mediators of Akt signaling, also are phosphorylated in AML blasts. Phosphorylation of these proteins is inhibited by the mTOR inhibitor RAD001. Incubation of AML blasts with RAD001 induces only a small decrease in survival of the cells; however, when combined with Ara-C, RAD001 enhances the toxicity of Ara-C. These results demonstrate that constitutive activation of the PI3 kinase pathway is necessary for the survival of AML blasts and that targeting of this pathway with pharmacologic inhibitors may be of clinical benefit in treatment of AML.