An effective reinduction regimen for first relapse of adult acute lymphoblastic leukemia.

Current salvage regimens achieve complete remission (CR) in about a third of adults with relapsed/refractory acute lymphoblastic leukemia (ALL), and this represents a major barrier for performing allogeneic hematopoietic stem cell transplant (HSCT), the only potentially curative treatment. We conducted in adults with first relapse of ALL, a prospective clinical trial with intensive regimen derived from the pediatric Berlin-Frankfurt-Muenster-85 protocol, with addition of a continuous infusional multi-agent chemotherapy in phase II induction followed by consolidation with alternating monthly cycles. Objectives of this study included CR rate, leukemia-free survival (LFS) and toxicity of the regimen in adults. We report the outcome of 19 patients (19-51 years of age) treated prospectively on the study, as well as a subsequent cohort of 31 patients (18-53 years of age) treated off the study. Thirteen of 19 (68%) patients from the initial prospective study achieved CR, and the median overall survival (OS) of these 13 CR patients was 10.3 months. The median OS and LFS of all 19 patients were 5.6 and 4.3 months, respectively. The regimen was well tolerated, and no grade 4 non-hematological toxicity was observed. Of the 31 patients treated off the study and analyzed retrospectively, 16 (52%) achieved CR. After including all 50 patients, the CR rate was 58%. The regimen used in this trial appears to be feasible and effective salvage therapy option for adult patients younger than age 55 with relapsed ALL, produced a high CR rate and could facilitate subsequent allogeneic HSCT.

Pharmacodynamics and safety of intravenous pegaspargase during remission induction in adults aged 55 years or younger with newly diagnosed acute lymphoblastic leukemia.

In contrast to that in children, pharmacokinetic, pharmacodynamic, and safety information on pegaspargase in adults is very limited. We administered a single intravenous dose of pegaspargase (2000 IU/m2) as part of a standard frontline induction regimen to 25 adults with newly diagnosed acute lymphoblastic leukemia (ALL), and obtained serum samples on several time points. The population mean peak serum concentration of asparaginase enzymatic activity was 1 IU/mL, the elimination half-life was 7 days, and the volume of distribution was 2.43 L/m2. After the single dose, asparagine deamination was complete in all patients after 2 hours, and in 100%, 81%, and 44% on days 14, 21, and 28, respectively. A pharmocodynamic correlation model showed minimal enzymatic activity of 0.2 IU/mL for optimal asparagine depletion. The kinetic posthoc analyses demonstrated enzymatic activity for 3 weeks or more. One patient developed neutralizing antiasparaginase antibodies on day 22 after administration. Pegaspargase was well tolerated, with few grade 3/4 side effects. No allergic reactions or pancreatitis were observed. In adults aged 55 years or younger, pegaspargase produces a long duration of asparagine depletion and can be given intravenously, with a safety profile that is similar to equivalent multiple doses of intramuscular Escherichia coli asparaginase.

Acute promyelocytic leukaemia in patients originating in Latin America is associated with an increased frequency of the bcr1 subtype of the PML/RARalpha fusion gene.

The PML/RARalpha fusion gene in acute promyelocytic leukaemia (APL) has three subtypes based on the breakpoint site of the PML gene: long (bcr1), short (bcr3) and variable (bcr2) subtypes. The PML/RARalpha fusion protein is involved in the pathogenesis of APL and the breakpoint site of the PML gene might be associated with aetiological factor(s). Because APL is over-represented in patients that originate in Latin America (Latinos), we evaluated whether the distribution of the PML/RARalpha fusion mRNA in this population is different to that reported in non-Latinos. Among 52 APL patients (28 from Mexico and Central America diagnosed in Los Angeles and 24 from Peru, South America), bcr1, bcr2 and bcr3 expression was 75%, 10% and 15% respectively. However, bcr1 breakpoints were significantly higher compared with non-Latino patients (340/654, 52%) reported in four studies. Often bcr1 and bcr2 are reported together; 862 (60%) of 1429 non-Latino APL patients reported in nine studies were either bcr1 or bcr2, compared with 44 (85%) in our 52 Latino patients. This difference was also statistically significant when our patients were compared to each of the individual studies from USA and Europe, but not for a small series from China and Japan. These results suggest that the overrepresentation of APL among Latin American patients can be accounted for by an increase of a single subtype--bcr1, and the breakage sites in the PML gene may not be random but possibly influenced by genetic and/or environmental factor(s).

Induction of complete remission using single agent clofarabine in a patient with primary refractory acute myeloblaste leukemia.

Refractory AML patients have a very poor prognosis. Therefore, rationally designed new therapies, including clofarabine, are being investigated as potential treatments for this patient population. This is a case report of a patient with primary refractory AML who was treated with clofarabine and achieved a complete response.