Outcome of treatment after first relapse in younger adults with acute myeloid leukemia initially treated by the ALFA-9802 trial

The Novel Phospholipid Mimetic KPC34 Is Highly Active Against Acute Myeloid Leukemia with Activated Protein Kinase C

Acute myeloid leukemia (AML) is an aggressive malignancy with poor outcomes. Nucleoside analogs are subject to resistance mechanisms including downregulation of equilibrative nucleoside transporter (ENT1) and deoxycytidine kinase (dCK). KPC34 is a novel phospholipid mimetic that when cleaved by phospholipase C (PLC) liberates gemcitabine monophosphate and a diacylglycerol mimetic that inhibits the classical isoforms of protein kinase C (PKC). KPC34 acts independently of ENT1 and dCK. KPC34 was active against all AML cell lines tested with IC₅₀s in the nanomolar range. Enforced expression of PLC increased response to KPC34 in vivo. In an orthotopic, xenograft model, KPC34 treatment resulted in a significant increase in survival compared to control animals and those treated with high-dose cytarabine. In a PDX model with activated PKC, there was a significant survival benefit with KPC34, and at progression, there was attenuation of PKC activation in the resistant cells. In contrast, KPC34 was ineffective against a syngeneic, orthotopic AML model without activated PKC. However, when cells from that model were forced to express PKC, there were significantly increased sensitivity in vitro and survival benefit in vivo. These data suggest that KPC34 is active against AML and that the presence of activated PKC can be a predictive biomarker.

Lyon-University Hospital Experience with Gemtuzumab Ozogamicin Therapy in Acute Myeloid Leukemia: a 'Real-Life' Study

Ninety-four adults with newly diagnosed or relapsed/refractory acute myeloid leukemia (AML) were treated with fractionated doses of gemtuzumab ozogamicin (GO) at one-single French center over ten years. We attempted to define predictive factors for response and survival. The overall response rate was 70% (86% in newly diagnosed and 65% in relapsed/refractory AML). Mortality during induction was 6%. Disease-free survival (DFS) and overall survival at three years after GO treatment was 36% and 31%, respectively. Median DFS in relapsed/refractory patients was eight months with a 3-year DFS at 34%. Among remitters, allogeneic hematopoietic stem cell transplantation (HSCT) can be performed in 28 cases (42%), including two patients in first-line therapy and 26 in further line. In relapsed/refractory patients undergoing allogeneic HSCT after responding to GO therapy, the median DFS was not reached. Incidences of transplant-related mortality, grade ≥ 3 acute graft-versus-host (GvH) disease, and extensive chronic GvH disease were 11%, 14%, and 25%, respectively. No sinusoidal obstruction syndromes were reported among allografted patients as among the other patients in the studied cohort. GO-based chemotherapy is a viable option for the treatment of relapsed/refractory AML patients and is a feasible schedule as a bridge to allogeneic transplant.

Serum Flt3 ligand is a biomarker of progenitor cell mass and prognosis in acute myeloid leukemia

Fms-like tyrosine kinase 3 (Flt3) is expressed on progenitor cells and acute myeloid leukemia (AML) blasts. Fms-like tyrosine kinase 3 ligand (Flt3L) is detectable during homeostasis and increases in hypoplasia due to genetic defects or treatment with cytoreductive agents. Conversely, Flt3+ AML is associated with depletion of Flt3L to undetectable levels. After induction chemotherapy, Flt3L is restored in patients entering complete remission (CR) but remains depressed in those with refractory disease. Weekly sampling reveals marked differences in the kinetics of Flt3L response during the first 6 weeks of treatment, proportionate to the clearance of blasts and cellularity of the bone marrow. In the UK NCRI AML17 trial, Flt3L was measured at day 26 in a subgroup of 140 patients with Flt3 mutation randomized to the tyrosine kinase inhibitor lestaurtinib or placebo. In these patients, attainment of CR was associated with higher Flt3L at day 26 (Mann-Whitney UP < .0001). Day 26 Flt3L was also associated with survival; Flt3L ≤291 pg/mL was associated with inferior event-free survival (EFS), and Flt3L >1185 pg/mL was associated with higher overall survival (OS; P = .0119). The separation of EFS and OS curves increased when minimal residual disease (MRD) status was combined with Flt3L measurement, and Flt3L retained a near-significant association with survival after adjusting for MRD in a proportional hazards model. Serial measurement of Flt3L in patients who had received a hematopoietic stem cell transplant for AML illustrates the potential value of monitoring Flt3L to identify relapse. Measurement of Flt3L is a noninvasive test with the potential to inform clinical decisions in patients with AML.

[Current indications of allogeneic stem cell transplant in adults with acute myeloid leukemia]

Allogeneic stem cell transplantation (SCT) is an increasingly important therapeutic option for the treatment of adult patients with acute myeloid leukemia. Here we review the current indications of SCT in this disease. While patients with favorable cytogenetics should receive consolidation chemotherapy, patients with unfavorable karyotype are prime candidates for SCT or new approaches to SCT (which should be done in first complete remission). Patients with intermediate prognoses should also receive SCT in first complete remission. In the absence of a suitable matched related donor, most patients will be able to find an alternative donor to proceed to a potentially curative allogeneic transplantation. The use of reduced-intensity conditioning regimens before SCT has allowed patients in the sixth or seventh decades of life to be routinely transplanted. Despite major differences among transplant centers in the intensity and composition of the conditioning regimen and immunosuppression, choice of graft source, postgraft immune-modulation, and supportive care, there has been a dramatic improvement in terms of tolerance. Although it is presumed to be a curative strategy, major complications of SCT remain graft-versus-host disease, delayed immune recovery, multiple comorbidities, and relapse after transplant.

SWOG0919: a Phase 2 study of idarubicin and cytarabine in combination with pravastatin for relapsed acute myeloid leukaemia

Inhibition of cholesterol synthesis and uptake sensitizes acute myeloid leukaemia (AML) blasts to chemotherapy. A Phase 1 study demonstrated the safety of high dose pravastatin given with idarubicin and cytarabine in patients with AML and also demonstrated an encouraging response rate. The Southwestern Oncology Group (SWOG) trial, SWOG S0919, was a Phase 2 trial evaluating the complete remission (CR) rate in a larger number of patients with relapsed AML treated with idarubicin, cytarabine and pravastatin. This study closed to accrual after meeting the defined criterion for a positive study. Thirty-six patients with a median age of 59 years (range 23-78) were enrolled. The median time from diagnosis to registration was 18 months. Relapse status was first relapse, 17 patients (47%); second relapse, 15 patients (42%); third relapse, two patients (5·5%) and fourth relapse, two patients (5·5%). The response rate was 75% [95% confidence interval: 58-88%; 20 CRs, 7 CR with incomplete count recovery (CRi)], and the median overall survival was 12 months. The P-value comparing 75-30% (the null response rate based on prior SWOG experience) was 3·356 × 10(-4) . Given the encouraging CR/CRi rate, this regimen should be considered for testing in a prospective randomized trial against best conventional therapy.