Prospective cohort study comparing intravenous busulfan to total body irradiation in hematopoietic cell transplantation.

We conducted a prospective cohort study testing the noninferiority of survival of ablative intravenous busulfan (IV-BU) vs ablative total body irradiation (TBI)-based regimens in myeloid malignancies. A total of 1483 patients undergoing transplantation for myeloid malignancies (IV-BU, N = 1025; TBI, N = 458) were enrolled. Cohorts were similar with respect to age, gender, race, performance score, disease, and disease stage at transplantation. Most patients had acute myeloid leukemia (68% IV-BU, 78% TBI). Grafts were primarily peripheral blood (77%) from HLA-matched siblings (40%) or well-matched unrelated donors (48%). Two-year probabilities of survival (95% confidence interval [CI]), were 56% (95% CI, 53%-60%) and 48% (95% CI, 43%-54%, P = .019) for IV-BU (relative risk, 0.82; 95% CI, 0.68-0.98, P = .03) and TBI, respectively. Corresponding incidences of transplant-related mortality (TRM) were 18% (95% CI, 16%-21%) and 19% (95% CI, 15%-23%, P = .75) and disease progression were 34% (95% CI, 31%-37%) and 39% (95% CI, 34%-44%, P = .08). The incidence of hepatic veno-occlusive disease (VOD) was 5% for IV-BU and 1% with TBI (P < .001). There were no differences in progression-free survival and graft-versus-host disease. Compared with TBI, IV-BU resulted in superior survival with no increased risk for relapse or TRM. These results support the use of myeloablative IV-BU vs TBI-based conditioning regimens for treatment of myeloid malignancies.

Maximally tolerated busulfan systemic exposure in combination with fludarabine as conditioning before allogeneic hematopoietic cell transplantation.

Systemic exposure to high-dose busulfan has been correlated with efficacy and toxicity after hematopoietic cell transplantation for malignancy. We used the area under the concentration-time curve (AUC) to prospectively determine the maximally tolerated systemic exposure to i.v. busulfan when given once daily after fludarabine administered at 40 mg/m(2) for 4 days. Three target AUC levels were planned: 6,000, 7,500, and 9,000 µM-min. Included were patients 16 to 65 years old, with a hematologic malignancy, an HLA A, B, or C, DRB1 8/8 or 7/8 matched donor, Karnofsky performance status ≥70%, and adequate organ function. For level 1 patients, i.v. busulfan doses 1 and 2 were 170 mg/m(2)/day, then doses 3 and 4 were adjusted based on first-dose pharmacokinetic modeling to achieve an average daily AUC of 6,000 µM-min. Doses 1 and 2 for the subsequent cohorts were based on the level 1 data: 180 mg/m(2)/day for AUC 7,500 µM-min (level 2) and 220 mg/m(2)/day for AUC 9,000 µM-min (level 3), with pharmacokinetic targeting for doses 3 and 4. Pharmacokinetic analysis after the last dose showed that 88% of the patients had been exposed to a mean AUC within 10% of the target. Forty patients were treated at level 1, 29 patients at level 2, and three patients at level 3. DLT was veno-occlusive disease of the liver, which occurred in none of 40 patients (0%) at level 1, two of 29 patients (7%) at level 2, and three of three patients (100%) at level 3. Dermatitis (P < .01) and pulmonary toxicity (P = .01) were also increased at higher AUC levels. Level 2 (7,500 µM-min × 4 days) was the maximally tolerated AUC. Within the confines of the trial's small sample size, there was no suggestion that escalating busulfan AUC from 6,000 to 7,500 µM-min × 4 days increased nonrelapse mortality. Assessment of the higher busulfan AUC on relapse prevention requires trials in patients with a homogeneous risk of relapse.

Autologous versus reduced-intensity allogeneic hematopoietic cell transplantation for patients with chemosensitive follicular non-Hodgkin lymphoma beyond first complete response or first partial response.

Patients with follicular lymphoma (FL) typically experience an indolent course; however, the disease is rarely curable with conventional chemotherapy. Autologous hematopoietic cell transplantation (HCT) can extend progression-free survival (PFS) and overall survival (OS), but relapse is the primary cause of failure. Allogeneic HCT confers lower relapse rates due to a graft-versus-lymphoma effect. Reduced-intensity conditioning (RIC) allows the performance of allogeneic HCT with lower toxicity. The Blood and Marrow Transplant Clinical Trials Network conducted a prospective multicenter trial comparing these two strategies in patients with relapsed, chemotherapy-sensitive FL. Patients were assigned to a treatment arm based on the availability of an HLA-matched sibling donor (MSD). Those with an MSD underwent allogeneic HCT (n = 8) with the FCR preparative regimen (fludarabine, cyclophosphamide [Cy], rituximab [RTX]) and received tacrolimus and methotrexate for graft-versus-host disease (GVHD) prophylaxis. Those without an MSD (n = 22) underwent mobilization with Cy, RTX, and filgrastim and received a conditioning regimen of either CBV (Cy, carmustine, Etoposide [VP16]) or total body irradiation with Cy and VP16. Patients undergoing autologous HCT received 4 doses of weekly maintenance RTX (375 mg/m²) starting on day +42 post-HCT. Sixteen patients were in complete remission, 10 patients were in partial remission, and 1 patient had stable disease after salvage therapy and before HCT. Median follow-up was 36 months (range, 1-51 months). OS was 73% in autologous HCT versus 100% in allogeneic HCT, and PFS was 63% in autologous HCT versus 86% in allogeneic HCT. No patient had grade II-IV acute GVHD; two patients developed extensive chronic GVHD. Three autologous recipients died from nonrelapse causes. This trial closed early because of slow accrual. We show that the FCR regimen is well tolerated, and that both allogeneic and autologous HCT result in promising 3-year OS and PFS in patients with relapsed FL.

New developments in antibody therapy for acute myeloid leukemia.

In the past three decades, improvements in the treatment of acute myeloid leukemia (AML) have increased survival in patients younger than 55 years without significant survival impact in older individuals. Unfortunately, many patients, regardless of age at diagnosis, will eventually die from their disease. Advances in the development of targeted therapies have proven beneficial in chronic myeloid leukemia and lymphoma. Gemtuzumab ozogamicin (GO; Mylotarg, Wyeth-Ayerst, St Davids, PA), a monoclonal antibody conjugated to calicheamicin, targets the CD33 antigen found on the surface of more than 80% of AML leukemic blasts. GO is approved for relapsed disease in patients older than 60 years, but is being evaluated in combination with chemotherapy, in the setting of hematopoietic stem cell transplant, and in high-risk myelodysplasia.

Myeloablative hematopoietic cell transplantation for acute lymphoblastic leukemia: analysis of graft sources and long-term outcome.

PURPOSE: Analysis of hematopoietic cell transplantation (HCT) for high-risk or recurrent acute lymphoblastic leukemia (ALL) using different donor sources is confounded by variable conditioning and supportive care. PATIENTS AND METHODS: We studied 623 consecutive ALL myeloablative HCT (1980 to 2005). Donors were autologous (n = 209), related (RD; n = 245), unrelated (URD; n = 100), and umbilical cord blood (UCB; n = 69). RESULTS: After median of 8.3 years of follow-up, 5-year overall survival (OS), leukemia-free survival (LFS), and relapse were 29% (95% CI, 26% to 32%), 26% (95% CI, 23% to 29%), and 43% (95% CI, 39% to 47%), respectively. Treatment-related mortality (TRM) at 2 years was 28% (95% CI, 25% to 31%). Mismatched URD sources yielded higher TRM (relative risk [RR], 2.2; P < .01) and lower OS (RR, 1.5; P = .05) than RD or UCB HCT. Autografting yielded significantly more relapse (68%; 95% CI, 59% to 77%; P < .01) and poorer LFS (14%; 95% CI, 10% to 18%; P = .01). HCT in first complete remission (CR1) yielded significantly better outcomes than later HCT. In a 1990 to 2005 allogeneic CR1/second complete response cohort, 5-year OS, LFS, and relapse rates were 41% (95% CI, 35% to 47%), 38% (95% CI, 32% to 44%), and 25% (95% CI, 19% to 31%), respectively; 2-year TRM was 34% (95% CI, 28% to 40%). With RD, well-matched URD and UCB sources, 5-year LFS was 40% (95% CI, 31% to 49%), 42% (95% CI, 14% to 70%), and 49% (95% CI, 34% to 64%), respectively, while relapse was 31% (95% CI, 22% to 40%), 17% (95% CI, 0% to 37%), and 27% (95% CI, 13% to 41%). Acute graft-versus-host disease was associated with fewer relapses. Since 1995, we noted progressive improvements in OS, LFS, and TRM. CONCLUSION: Allogeneic, but not autologous, HCT for ALL results in durable LFS. Importantly, HCT using UCB led to similar outcomes as either RD or well-matched URD. HCT in early remission can best exploit the potent antileukemic efficacy of allografting from UCB, RD, or URD sources.

Are there circumstances in which phase 2 study results should be practice-changing?

New pharmaceuticals, innovative combinations of approved agents, and novel treatment modalities have resulted in a marked increase in the need for clinical trials. Evidence for treatment efficacy is best derived from large phase 3 randomized, controlled clinical trials. However, phase 3 investigations are lengthy and expensive, and consume patient resources. Furthermore, some diseases and treatment indications are rare, and adequate numbers of patients for a definitive phase 3 trial do not exist. Consequently, it is imperative for clinicians to understand phase 2 trial design, since their interpretation is required to apply the findings in clinical practice appropriately. The complexity of phase 2 studies is explored, including unique designs, possible use of randomization, and other key elements necessary for interpretation of phase 2 trials. Specific examples and application of these concepts are discussed in this review.