Evaluation of residual CD34(+) Ph(+) progenitor cells in chronic myeloid leukemia patients who have complete cytogenetic response during first-line nilotinib therapy.

BACKGROUND: Compared with imatinib, nilotinib is a potent breakpoint cluster region/v-abl Abelson murine leukemia viral oncogene (bcr-abl) kinase inhibitor, and it induces higher rate and rapid complete cytogenetic response (CCyR), yet no clinical data are available regarding its efficacy against chronic myeloid leukemia (CML) stem cells. Earlier studies demonstrated that clusters of differentiation 34-positive, Philadelphia chromosome-positive (CD34(+) Ph(+) ) cells are detectable in about 45% of patients with CML, despite being on long-term imatinib therapy and having achieved sustained CCyR. METHODS: CD34(+) cells from bone marrow of de novo CML patients in the chronic phase (n = 24) treated with nilotinib (median duration of therapy, 22 months) were isolated and scored for BCR-ABL by fluorescent in situ hybridization (FISH) analysis. Similar analysis was also performed in 5 de novo CML chronic phase patients who achieved CCyR within 3 months of nilotinib therapy. RESULTS: FISH evaluation of a median of 100 CD34(+) nuclei per patient revealed that only 1 of 20 (5%) evaluable patients showed residual Ph(+) progenitor cells. In this patient, just 1 of 140 (0.7%) CD34(+) interphase nuclei was found to be positive for BCR-ABL. Surprisingly, no CD34(+) Ph(+) cells were found even in those 5 patients evaluated after 3 months of nilotinib treatment. CONCLUSIONS: This study assessed for the first time the persistence of CD34(+) Ph(+) cells during nilotinib first-line treatment. Preliminary results showed that in patients in CCyR, even after short-term nilotinib therapy, residual leukemic progenitors are very rarely detected compared with imatinib-treated CCyR patients. It is yet to be determined if these findings will have an impact in the path to a cure of CML with tyrosine kinase inhibitors.

Lower dose rituximab is active in adults patients with idiopathic thrombocytopenic purpura.

Rituximab 375 mg/m(2) weekly for four weeks has significant activity in patients with immune thrombocytopenia. We evaluated the activity of lower dose rituximab (100 mg iv weekly for 4 weeks) in 28 adults with idiopathic thrombocytopenic purpura. Overall (platelet count > 50 x 10(9)/L) and complete responses (platelet count > 100 x 10(9)/L) were achieved in 21/28 (75%) and 12/28 (43%) patients respectively. The median time to response and time to complete response were 31 and 44 days respectively. After a median follow-up of 11 months (range 3-18), 7/21 (33%) patients relapsed and 3 needed further treatments. In patients with idiopathic thrombocytopenic purpura, lower dose rituximab seems to show similar activity to standard dose.

Antibody binding capacity for evaluation of MDR-related proteins in acute promyelocytic leukemia: Onset versus relapse expression.

BACKGROUND: Multidrug resistance (MDR) remains a major obstacle for successful treatment in cancer, in particular in acute leukemia. In acute promyelocytic leukemia (APL), the high sensitivity to anthracyclines appears to be attributable to the low frequency of MDR proteins overexpression at onset even if 30% of patients still relapse and become resistant to therapy. In attempt to explain different blast cell sensitivity, we studied the expression of PGP, MRP1, MRP2, and LRP in 45 cases of APL, comparing onset of disease with relapse. METHODS: PGP, LRP, and MRP on bone marrow or peripheral blood blast cells were evaluated by flow cytometry using the MRK-16, LRP-56, MRP-m6, and MRP2 antibodies and results expressed by the mean fluorescence index (MFI). The antibody binding capacity (ABC) for each MDR protein was also calculated. RESULTS: At diagnosis, only 2 of 45 patients overexpressed PGP and 1 overexpressed LRP. PGP and LRP overexpressing cases significantly grew up during disease progression and at second relapse mean PGP MFI and mean LRP MFI were significantly higher than at onset (P = 0.001 and P = 0.008, respectively). By analyzing ABC, the same trend was more evident because a significant increment of PGP and LRP was observed at second (P = 0.002 and P = 0.002, respectively), but even at first relapse (P = 0.018 and P = 0.002, respectively). No changes were demonstrated in MRP1 and MRP2 expression in any phase of disease considered. CONCLUSIONS: Our data confirm the low expression at diagnosis of proteins related to development of drug resistance in APL. The evidence of a relative easy induction of PGP and LRP, but not of MRP, can be useful in choosing drugs to employ for consolidation or rescue therapy.

Identification of a novel p190-derived breakpoint Peptide suitable for Peptide vaccine therapeutic approach in ph+ acute lymphoblastic leukemia patients.

Ph+ acute lymphoblastic leukemia (Ph+ ALL) is a high-risk acute leukemia with poor prognosis, in which the specific t(9;22)(q34;q11) translocation results in a chimeric bcr-abl (e1a2 breakpoint) and in a 190 KD protein (p190) with constitutive tyrosine kinase activity. The advent of first- and second-generation tyrosine kinase inhibitors (TKIs) improved the short-term outcome of Ph+ ALL patients not eligible for allo-SCT; yet disease recurrence is almost inevitable. Peptides derived from p190-breakpoint area are leukemia-specific antigens that may mediate an antitumor response toward p190+ leukemia cells. We identified one peptide named p190-13 able to induce in vitro peptide-specific CD4+ T cell proliferation in Ph+ ALL patients in complete remission during TKIs. Thus this peptide appears a good candidate for developing an immune target vaccine strategy possibly synergizing with TKIs for remission maintenance.

Complete molecular response in CML after p210 BCR-ABL1-derived peptide vaccination.

BACKGROUND: A 63-year-old woman with chronic myeloid leukemia (CML) received treatment with interferon (IFN)-α for 6 years. After achieving a complete cytogenetic response that was repetitively documented, IFN-α treatment was stopped. Despite maintenance of a complete cytogenetic response, a progressive rise of the BCR-ABL1 transcript was detected and loss of major molecular response occurred about 2 years after stopping IFN-α therapy. Disease remained at molecular level. INVESTIGATIONS: Peripheral blood quantitative real-time PCR every 3 months and periodical bone marrow aspirate were performed to monitor disease. DIAGNOSIS: Chronic-phase, Philadelphia-positive CML that was still detectable after complete cytogenic response 2 years after cessation of IFN-α therapy. MANAGEMENT: The patient was treated with a target immune approach receiving a therapeutic vaccine that consisted of an immunogenic 25-mer b2a2 breakpoint-derived peptide (CMLb2a2-25) with binding properties for several HLA-DR molecules. After nine boosts of vaccine the patient developed an adequate b2a2-25 peptide-specific CD4(+) T-cell response and BCR-ABL1 transcript started to decline in peripheral blood. No hematological or extrahematological effects were documented during therapy. At the last evaluation, 39 months since vaccinations commenced, the patient is in complete molecular response with an undetectable level of BCR-ABL1 transcript both in peripheral blood and in bone marrow and she continues to receive boosts of vaccine every 3 months as the only treatment.

Hairy cell leukemia: at the crossroad of somatic mutation and isotype switch.

Hairy cell leukemia (HCL) commonly expresses multiple immunoglobulin isotypes, a feature rare in other B-cell malignancies or in normal B cells. In HCL, there is no phenotypic evidence for subpopulations, and single cells from one previous case contained transcripts for several isotypes. This raises the questions of the differentiation status of the cell of origin and of posttransformation events. We have investigated 9 cases, all expressing multiple immunoglobulin isotypes. Multiple tumor-derived variable-(diversity)-joining-constant mu delta, gamma, alpha (V(D)J-Cmu, delta, gamma, alpha) transcripts were confirmed in single cells of a further case. All cases were negative for germinal center (GC)-associated markers CD27 and CD38. Seven of 9 cases had mutated V(H) genes, with low levels of intraclonal heterogeneity, but 2 of 9 were unmutated, indicative of pre-GC origin. Eight of 9 cases expressed activation-induced cytidine deaminase (AID), a molecule essential for somatic mutation and isotype switch. All cases expressed germ line heavy-chain I exon (I(H))-C(H) transcripts which paralleled surface immunoglobulin (sIg) isotype. Significantly, no circle transcripts indicative of deletional recombination of switched isotypes were detectable in 9 of 9 cases. These data indicate heterogeneity in the cell of origin in terms of mutational status, but reveal common features of AID expression and isotype-switching events occurring prior to deletional recombination. Both mutational and switching events may be influenced by environmental factors at extrafollicular sites.