Roel Willemze

This study aims to determine the maximum tolerated dose (MTD) of clofarabine combined with the EORTC-GIMEMA 3 + 10 induction regimen (idarubicin + cytosine arabinoside) in adults with untreated acute myelogenous leukemia or high-risk myelodysplastic syndrome. In this phase I trial, 25 patients (median age 56 years) received 5 days of clofarabine as 1-h infusion (arm A) or push injection (arm B) at the dose level of 5 × 10 or 5 × 15 mg/m²/day in an algorithmic dose escalation 3 + 3 design. A consolidation course (intermediate dose cytosine arabinoside, idarubicin) was planned for patients in complete remission (CR). Primary endpoint was safety and tolerance as measured by dose limiting toxicity (DLT); secondary endpoints were response rate, other grade III/IV toxicities, and hematological recovery after induction and consolidation. Five DLTs were observed (in arm A: one DLT at 10 mg/m²/day, three at 15 mg/m²/day; in arm B: one DLT at 15 mg/m²/day). Three patients receiving 15 mg/m²/day were withdrawn due to adverse events not classified as DLT. Prolonged hypoplasia was observed in five patients. CR + complete remission with incomplete recovery were achieved in 21 patients (11/12 (92 %) receiving clofarabine 10 mg/m²/day; 10/13 (77 %) receiving clofarabine 15 mg/m²/day). Clofarabine, 5 × 10 mg/m²/day, resulted in one DLT and no early treatment withdrawals. MTD of clofarabine combined with cytosine arabinoside and idarubicin is 5 × 10 mg/m²/day.

Donor killer cell immunoglobulin-like receptor (KIR)-ligand incompatibility is associated with decreased relapse incidence (RI) and improved leukemia-free survival (LFS) after haploidentical and HLA-mismatched unrelated hematopoietic stem cell transplantation. We assessed outcomes of 218 patients with acute myeloid leukemia (AML n=94) or acute lymphoblastic leukemia (n=124) in complete remission (CR) who had received a single-unit unrelated cord blood transplant (UCBT) from a KIR-ligand-compatible or -incompatible donor. Grafts were HLA-A, -B or -DRB1 matched (n=21) or mismatched (n=197). Patients and donors were categorized according to their degree of KIR-ligand compatibility in the graft-versus-host direction by determining whether or not they expressed HLA-C group 1 or 2, HLA-Bw4 or HLA-A3/-A11. Both HLA-C/-B KIR-ligand- and HLA-A-A3/-A11 KIR-ligand-incompatible UCBT showed a trend to improved LFS (P=0.09 and P=0.13, respectively). Sixty-nine donor–patient pairs were HLA-A, -B or -C KIR-ligand incompatible and 149 compatible. KIR-ligand-incompatible UCBT showed improved LFS (hazards ratio=2.05, P=0.0016) and overall survival (OS) (hazards ratio=2.0, P=0.004) and decreased RI (hazards ratio=0.53, P=0.05). These results were more evident for AML transplant recipients (2-year LFS and RI with or without KIR-ligand incompatibility 73 versus 38% (P=0.012), and 5 versus 36% (P=0.005), respectively). UCBT for acute leukemia in CR from KIR-ligand-incompatible donors is associated with decreased RI and improved LFS and OS.

Acute myeloid leukemia (AML) in the elderly is associated with low rates of response to conventional chemotherapy and long-term survival, highlighting the need for innovative treatment strategies. Gemtuzumab ozogamicin (GO) is an immunoconjugate that has shown activity in relapsed AML with a favorable safety profile. The aim of this collaborative trial was to assess the feasibility, safety, and antileukemic activity of administering GO followed by conventional chemotherapy as first line therapy in patients aged 61-75 years with AML. Eligible patients received frontline treatment with GO 9 mg/m2 infused intravenously on days 1 and 15. Following response assessment to GO, patients were started on conventional chemotherapy consisting of the MICE regimen (mitoxantrone, cytarabine, etoposide). No further treatment was planned for complete responders. Among the 57 evaluable patients, 38 (67%) completed the entire sequential treatment as planned. The overall response rate to the entire induction sequence was 54.4% (31/57), with complete remission (CR) in 35.1% and complete remission with incomplete platelet recovery (CRp) in 19.3%. Rates of failure due to treatment-related mortality or resistant disease were 14.1% (3 toxic deaths during the GO segment, 5 during MICE) and 29.9%, respectively. An initial response to GO was documented in 20 patients (35.1%), with CR in 22.8% and CRp in 12.3%; 6 additional patients entered a partial remission. Reversible myelosuppression and liver toxicity were the main adverse events during both segments of induction. Frontline GO was associated with modest mucosal and gastrointestinal toxicity, but grade 3-4 pancytopenia was universal and prolonged. Hepatic veno-occlusive disease developed in 3 patients after GO and 2 after MICE, resulting in 4 deaths from liver failure. One-year survival at follow-up was 34%. Twelve patients continue in CR/CRp after a median of 226 days. The sequential combination of GO and conventional chemotherapy is a feasible and active treatment strategy for older patients with untreated AML. This novel regimen is now being compared in a phase III trial (AML-17).

In the EORTC ALL-3 trial, the efficacy of allogeneic transplantation was compared with that of autologous marrow transplantation and maintenance chemotherapy in patients <or= 50 years who reached CR. Among 340 patients who entered the study, 279 were <or=50 years old. Out of these, 220 reached CR, 184 patients started consolidation and were HLA typed; 68 had a donor and 116 had no sibling donor. The median follow-up was 9.5 years; 93 patients relapsed, 26 died in CR, and overall 116 patients died. Allogeneic transplantation was performed in 47 (68%) patients with a donor while autologous transplantation or maintenance chemotherapy was given to 84 (72%) patients without a sibling donor. The 6-year disease-free survival rate was similar in the groups with and without donor [38.2% (SE=5.9%) vs. 36.8% (SE=4.6%), hazard ratio 1.01, 95% CI 0.67-1.53]. Comparing the donor group with the no donor group, the former had a lower relapse incidence (38.2% vs. 56.3%, p=0.001), but a higher cumulative incidence of death in CR (23.5% vs. 6.9%, p=0.0004). The 6-year survival rates were similar [41.2% (SE=6.0%) vs. 38.8% (SE=4.6%)]. This trial did not show that allogeneic transplantation, when a sibling donor is available, produces a better outcome than the policy of offering autotransplantation or chemotherapy in the absence of a donor.