Christophe Willekens

Enasidenib in mutant IDH2 relapsed or refractory acute myeloid leukemia

Recurrent mutations in isocitrate dehydrogenase 2 (IDH2) occur in ∼12% of patients with acute myeloid leukemia (AML). Mutated IDH2 proteins neomorphically synthesize 2-hydroxyglutarate resulting in DNA and histone hypermethylation, which leads to blocked cellular differentiation. Enasidenib (AG-221/CC-90007) is a first-in-class, oral, selective inhibitor of mutant-IDH2 enzymes. This first-in-human phase 1/2 study assessed the maximum tolerated dose (MTD), pharmacokinetic and pharmacodynamic profiles, safety, and clinical activity of enasidenib in patients with mutant-IDH2 advanced myeloid malignancies. We assessed safety outcomes for all patients and clinical efficacy in the largest patient subgroup, those with relapsed or refractory AML, from the phase 1 dose-escalation and expansion phases of the study. In the dose-escalation phase, an MTD was not reached at doses ranging from 50 to 650 mg per day. Enasidenib 100 mg once daily was selected for the expansion phase on the basis of pharmacokinetic and pharmacodynamic profiles and demonstrated efficacy. Grade 3 to 4 enasidenib-related adverse events included indirect hyperbilirubinemia (12%) and IDH-inhibitor-associated differentiation syndrome (7%). Among patients with relapsed or refractory AML, overall response rate was 40.3%, with a median response duration of 5.8 months. Responses were associated with cellular differentiation and maturation, typically without evidence of aplasia. Median overall survival among relapsed/refractory patients was 9.3 months, and for the 34 patients (19.3%) who attained complete remission, overall survival was 19.7 months. Continuous daily enasidenib treatment was generally well tolerated and induced hematologic responses in patients for whom prior AML therapy had failed. Inducing differentiation of myeloblasts, not cytotoxicity, seems to drive the clinical efficacy of enasidenib. This trial was registered at www.clinicaltrials.gov as #NCT01915498.

Characteristic repartition of monocyte subsets as a diagnostic signature of chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome/ myeloproliferative neoplasm whose diagnosis is currently based on the elevation of peripheral blood monocytes to >1 × 10(9)/L, measured for ≥3 months. Diagnosis can be ambiguous; for example, with prefibrotic myelofibrosis or reactive monocytosis. We set up a multiparameter flow cytometry assay to distinguish CD14(+)/CD16(-) classical from CD14(+)/CD16(+) intermediate and CD14(low)/CD16(+) nonclassical monocyte subsets in peripheral blood mononucleated cells and in total blood samples. Compared with healthy donors and patients with reactive monocytosis or another hematologic malignancy, CMML patients demonstrate a characteristic increase in the fraction of CD14(+)/CD16(-) cells (cutoff value, 94.0%). The associated specificity and sensitivity values were 95.1% and 90.6% in the learning cohort (175 samples) and 94.1% and 91.9% in the validation cohort (307 samples), respectively. The accumulation of classical monocytes, which demonstrate a distinct gene expression pattern, is independent of the mutational background. Importantly, this increase disappears in patients who respond to hypomethylating agents. We conclude that an increase in the fraction of classical monocytes to >94.0% of total monocytes is a highly sensitive and specific diagnostic marker that rapidly and accurately distinguishes CMML from confounding diagnoses.

Rituximab–cyclophosphamide–dexamethasone combination in the management of autoimmune cytopenias associated with chronic lymphocytic leukemia

We report our experience on rituximab–cyclophosphamide–dexamethasone (RCD) combination therapy for the treatment of autoimmune disorders (AIDs) in 48 chronic lymphocytic leukemia (CLL) patients. Overall, 81% of patients were relapsing for AID after previous treatment with corticosteroids, splenectomy, rituximab or alemtuzumab. Diagnosis of AID was autoimmune hemolytic anemia (AIHA) in 26 (54%), autoimmune thrombocytopenia (AITP) in 9 (18.8%), Evans syndrome in 8 (16.7%) and pure red cell aplasia (PRCA) in 5 patients (10.5%). Median time of autoimmune disorder (AID) onset from CLL diagnosis was 60 months (range: 0–240), and CLL was considered progressive in 40% of subjects upon AID diagnosis (complex AID). Median hemoglobin pre-treatment was 7.7 g/100 ml, and median platelet count 36.5 × 109/l, returning to a median of 12.5 /100ml and 37.5 × 109/l, respectively. Overall, an 89.5% response rate was obtained with this combination, irrespective of the AID type. Relapse occurred in 19 patients (39.6%). Median duration of response for autoimmunity (DR-AI) was 24 months, but DR-AI was higher for patients presenting: (1) AID early during CLL course (<3 years), or (2) both PRCA and AIHA. Median time to CLL progression in 48 patients was 16 months, but this time was statistically shorter for Evans syndrome and AITP patients as compared with AIHA and PRCA patients. This study emphasizes the relevance of CLL-directed immune chemotherapy in the management of CLL-associated AID.

IDH1 and IDH2 mutations as novel therapeutic targets: current perspectives.

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are key metabolic enzymes that convert isocitrate to α-ketoglutarate. IDH1/2 mutations define distinct subsets of cancers, including low-grade gliomas and secondary glioblastomas, chondrosarcomas, intrahepatic cholangiocarcinomas, and hematologic malignancies. Somatic point mutations in IDH1/2 confer a gain-of-function in cancer cells, resulting in the accumulation and secretion in vast excess of an oncometabolite, the D-2-hydroxyglutarate (D-2HG). Overproduction of D-2HG interferes with cellular metabolism and epigenetic regulation, contributing to oncogenesis. Indeed, high levels of D-2HG inhibit α-ketoglutarate-dependent dioxygenases, including histone and DNA demethylases, leading to histone and DNA hypermethylation and finally a block in cell differentiation. Furthermore, D-2HG is a biomarker suitable for the detection of IDH1/2 mutations at diagnosis and predictive of the clinical response. Finally, mutant-IDH1/2 enzymes inhibitors have entered clinical trials for patients with IDH1/2 mutations and represent a novel drug class for targeted therapy.

Durable Remissions with Ivosidenib in IDH1-Mutated Relapsed or Refractory AML

Background Mutations in the gene encoding isocitrate dehydrogenase 1 (IDH1) occur in 6 to 10% of patients with acute myeloid leukemia (AML). Ivosidenib (AG‐120) is an oral, targeted, small‐molecule inhibitor of mutant IDH1. Methods We conducted a phase 1 dose‐escalation and dose‐expansion study of ivosidenib monotherapy in IDH1‐mutated AML. Safety and efficacy were assessed in all treated patients. The primary efficacy population included patients with relapsed or refractory AML receiving 500 mg of ivosidenib daily with at least 6 months of follow‐up. Results Overall, 258 patients received ivosidenib and had safety outcomes assessed. Among patients with relapsed or refractory AML (179 patients), treatment‐related adverse events of grade 3 or higher that occurred in at least 3 patients were prolongation of the QT interval (in 7.8% of the patients), the IDH differentiation syndrome (in 3.9%), anemia (in 2.2%), thrombocytopenia or a decrease in the platelet count (in 3.4%), and leukocytosis (in 1.7%). In the primary efficacy population (125 patients), the rate of complete remission or complete remission with partial hematologic recovery was 30.4% (95% confidence interval [CI], 22.5 to 39.3), the rate of complete remission was 21.6% (95% CI, 14.7 to 29.8), and the overall response rate was 41.6% (95% CI, 32.9 to 50.8). The median durations of these responses were 8.2 months (95% CI, 5.5 to 12.0), 9.3 months (95% CI, 5.6 to 18.3), and 6.5 months (95% CI, 4.6 to 9.3), respectively. Transfusion independence was attained in 29 of 84 patients (35%), and patients who had a response had fewer infections and febrile neutropenia episodes than those who did not have a response. Among 34 patients who had a complete remission or complete remission with partial hematologic recovery, 7 (21%) had no residual detectable IDH1 mutations on digital polymerase‐chain‐reaction assay. No preexisting co‐occurring single gene mutation predicted clinical response or resistance to treatment. Conclusions In patients with advanced IDH1‐mutated relapsed or refractory AML, ivosidenib at a dose of 500 mg daily was associated with a low frequency of grade 3 or higher treatment‐related adverse events and with transfusion independence, durable remissions, and molecular remissions in some patients with complete remission. (Funded by Agios Pharmaceuticals; ClinicalTrials.gov number, NCT02074839.)

Prospective long-term minimal residual disease monitoring using RQ-PCR in RUNX1-RUNX1T1-positive acute myeloid leukemia: results of the French CBF-2006 trial

In t(8;21)(q22;q22) acute myeloid leukemia, the prognostic value of early minimal residual disease assessed with real-time quantitative polymerase chain reaction is the most important prognostic factor, but how long-term minimal residual disease monitoring may contribute to drive individual patient decisions remains poorly investigated. In the multicenter CBF-2006 study, a prospective monitoring of peripheral blood and bone marrow samples was performed every 3 months and every year, respectively, for 2 years following intensive chemotherapy in 94 patients in first complete remission. A complete molecular remission was defined as a (RUNX1-RUNX1T1/ABL1)×100 ≤ 0.001%. After the completion of consolidation therapy, a bone marrow complete molecular remission was observed in 30% of the patients, but was not predictive of subsequent relapse. Indeed, 8 patients (9%) presented a positive bone marrow minimal residual disease for up to 2 years of follow-up while still remaining in complete remission. Conversely, a peripheral blood complete molecular remission was statistically associated with a lower risk of relapse whatever the time-point considered after the completion of consolidation therapy. During the 2-year follow-up, the persistence of peripheral blood complete molecular remission was associated with a lower risk of relapse (4-year cumulative incidence, 8.2%), while molecular relapse confirmed on a subsequent peripheral blood sample predicted hematological relapse (4-year cumulative incidence, 86.9%) within a median time interval of 3.9 months. In t(8;21)(q22;q22) acute myeloid leukemia, minimal residual disease monitoring on peripheral blood every 3 months allows for the prediction of hematological relapse, and to identify patients who could potentially benefit from intervention therapy.

Outcome of patients with high risk Myelodysplastic Syndrome (MDS) and advanced Chronic Myelomonocytic Leukemia (CMML) treated with decitabine after azacitidine failure

Outcome of patients with high risk MDS and CMML who failed treatment with azacitidine remains poor with a median survival of 6 months, without established therapy available except allogeneic hematopoietic stem cell transplantation. The objective of our study was to evaluate efficacy of decitabine after azacitidine failure in a relatively large patient cohort based on conflicting results with 0-28% response rates (RR) in this setting in small patient series. Thirty-six consecutive high risk MDS and CMML patients who received decitabine after azacitidine failure were retrospectively reviewed. Response was based on IWG 2006 criteria for MDS and CMML with WBC<13G/l and also included for proliferative CMML the evolution of WBC, splenomegaly (SMG) and extramedullary disease (EMD). Patients received a median number of 3 (range 1-27) cycles of decitabine and 12 patients received at least 6 cycles. Seven (19.4%) patients were responders including 3 marrow CR (mCR), 2 stable disease (SD) with HI-E, 1 SD with HI-N and HI-P and 1 SD with HI-N. In a CMML patient with SD, specific skin lesions resolved with decitabine. Responses were generally short lived (2-5 months) except 1 responder currently ongoing with +11 months follow up. Two non-responders had prolonged SD (without HI) of 21 and 27 months duration respectively. Median OS from onset of decitabine was 7.3 months, without significant difference between responders and non-responders. Treatment with decitabine after azacitidine failure yielded modest ORR (19.4%) with short response duration and poor OS. Thus, use of decitabine in such patients who failed or progressed after azacitidine cannot be recommended, underscoring the need for novel strategies in this setting.

Bendamustine and rituximab combination in the management of chronic lymphocytic leukemia‐associated autoimmune hemolytic anemia: A multicentric retrospective study of the French CLL intergroup (GCFLLC/MW and GOELAMS)

We report our experience on bendamustine and rituximab (BR) combination in 26 patients with chronic lymphocytic leukemia (CLL) complicated by autoimmune hemolytic anemia (AIHA). At the time of BR initiation, 88% of the patients had already been treated for AIHA and CLL was progressive regardless of AIHA in all patients but one. Overall response rates were 81% for AIHA and 77% for CLL. Median time to next treatment was 28.3 months and 26.2 months for AIHA and CLL, respectively. BR therapy may represent a good and safe therapeutic option in this setting where adequate control of CLL seems important for long‐term AIHA response. Am. J. Hematol. 90:204–207, 2015.

Prognosis and monitoring of core-binding factor acute myeloid leukemia: current and emerging factors.

Core-binding factor acute myeloid leukemia (CBF-AML) – including AML with t(8;21) and AML with inv(16) – accounts for about 15% of adult AML and is associated with a relatively favorable prognosis. Nonetheless, relapse incidence may reach 40% in these patients. In this context, identification of prognostic markers is considered of great interest. Due to similarities between their molecular and prognostic features, t(8;21) and inv(16)-AML are usually grouped and reported together in clinical studies. However, considerable experimental evidences have highlighted that they represent two distinct entities and should be considered separately for further studies. This review summarizes recent laboratory and clinical findings in this particular subset of AML and how they could be used to improve management of patients in routine practice.

Minimal residual disease monitoring in t(8;21) acute myeloid leukemia based on RUNX1-RUNX1T1 fusion quantification on genomic DNA

Although acute myeloid leukemia (AML) with t(8;21) belongs to the favorable risk AML subset, relapse incidence may reach 30% in those patients. RUNX1‐RUNX1T1 fusion transcript is a well‐established marker for minimal residual disease (MRD) monitoring. In this study, we investigated the feasibility and performances of RUNX1‐RUNX1T1 DNA as MRD marker in AML with t(8;21). In 17/22 patients with t(8;21)‐positive AML treated in the French CBF‐2006 trial, breakpoints in RUNX1 and RUNX1T1 were identified using long‐range PCR followed by next‐generation sequencing. RUNX1‐RUNX1T1 DNA quantification was performed by real‐time quantitative PCR using patient‐specific primers and probe. MRD levels were evaluated in 71 follow‐up samples from 16 patients, with a median of four samples [range 2–7] per patient. RUNX1 breakpoints were located in intron 5 in all cases. RUNX1T1 breakpoints were located in intron 1b in 15 cases and in intron 1a in two cases. RUNX1‐RUNX1T1 MRD levels measured on DNA and RNA were strongly correlated (r = 0.8, P < 0.0001). Discordant MRD results were observed in 10/71 (14%) of the samples: in three samples from two patients who relapsed, RUNX1‐RUNX1T1 was detectable only on DNA, while RUNX1‐RUNX1T1 was detectable only on RNA in seven samples. MRD monitoring on genomic DNA is feasible, but with sensitivity variations depending on the patient breakpoint sequence and the qPCR assay efficiency. Although interpretation of the results is easier because it is closely related to the number of leukemic cells, this method greatly increases time, cost and complexity, which limits its interest in routine practice. Am. J. Hematol. 89:610–615, 2014.