Lara Aprile

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.

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

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.

Genetic predisposition and induced pro-inflammatory/pro-oxidative status may play a role in increased atherothrombotic events in nilotinib treated chronic myeloid leukemia patients

Several reports described an increased risk of cardiovascular (CV) events, mainly atherothrombotic, in Chronic Myeloid Leukemia (CML) patients receiving nilotinib. However, the underlying mechanism remains elusive. The objective of the current cross-sectional retrospective study is to address a potential correlation between Tyrosine Kinase Inhibitors (TKIs) treatment and CV events. One hundred and 10 chronic phase CML patients in complete cytogenetic response during nilotinib or imatinib, were screened for CV events and evaluated for: traditional CV risk factors, pro/anti-inflammatory biochemical parameters and detrimental ORL1 gene polymorphisms (encoding for altered oxidized LDL receptor-1). Multivariate analysis of the whole cohort showed that the cluster of co-existing nilotinib treatment, dyslipidaemia and G allele of LOX-1 polymorphism was the only significant finding associated with CV events. Furthermore, multivariate analysis according to TKI treatment confirmed IVS4-14 G/G LOX-1 polymorphism as the strongest predictive factor for a higher incidence of CV events in nilotinib patients. Biochemical assessment showed an unbalanced pro-inflammatory cytokines network in nilotinib vs imatinib patients. Surprisingly, pre-existing traditional CV risk factors were not always predictive of CV events. We believe that in nilotinib patients an induced “inflammatory/oxidative status”, together with a genetic pro-atherothrombotic predisposition, may favour the increased incidence of CV events. Prospective studies focused on this issue are ongoing.

Peptide vaccines for hematological malignancies: a missed promise?

Despite the crucial aid that newly developed target therapies are providing to chemotherapy and stem cell transplant, the cure for many hematological malignancies is still an unmet need. Although available therapies are able to induce an effective debulking of the tumor, most of the time, an insidious minimal residual disease survives current treatments and it is responsible for an immediate or delayed relapse. Peptide-derived antitumor vaccines have been developed with the idea that an artificially “educated” immune system may exert an active specific antitumor response able to control and ultimately eradicate underlying post-treatment residual disease. This review will summarize current knowledge of peptide vaccines for hematological malignancies, trying to analyze promises and pitfalls of a safe and intelligent tool that after many years from its first appearance has not yet established its potential role as alternative immune mediated therapeutic approach for hematopoietic tumors.

The hOCT1 and ABCB1 polymorphisms do not influence the pharmacodynamics of nilotinib in chronic myeloid leukemia

First-line nilotinib in chronic myeloid leukemia is more effective than imatinib to achieve early and deep molecular responses, despite poor tolerability or failure observed in one-third of patients. The toxicity and efficacy of tyrosine kinase inhibitors might depend on the activity of transmembrane transporters. However, the impact of transporters genes polymorphisms in nilotinib setting is still debated. We investigated the possible correlation between single nucleotide polymorphisms of hOCT1 (rs683369 [c.480C>G]) and ABCB1 (rs1128503 [c.1236C>T], rs2032582 [c.2677G>T/A], rs1045642 [c.3435C>T]) and nilotinib efficacy and toxicity in a cohort of 78 patients affected by chronic myeloid leukemia in the context of current clinical practice. The early molecular response was achieved by 81% of patients while 64% of them attained deep molecular response (median time, 26 months). The 36-month event-free survival was 86%, whereas 58% of patients experienced toxicities. Interestingly, hOCT1 and ABCB1 polymorphisms alone or in combination did not influence event-free survival or the adverse events rate. Therefore, in contrast to data obtained in patients treated with imatinib, hOCT1 and ABCB1 polymorphisms do not impact on nilotinib efficacy or toxicity. This could be relevant in the choice of the first-line therapy: patients with polymorphisms that negatively condition imatinib efficacy might thus receive nilotinib as first-line therapy.

Lenalidomide on alternative days is effective in myelodysplastic syndrome with 5q- deletion

Lenalidomide is the treatment of choice in low-risk patients with myelodysplastic syndrome (MDS) and 5qdeletion, at the standard dose of 10 mg for 21 d of every 28-d cycle (Giagounidis et al, 2008). The main response criteria is to achieve blood transfusion independence and recent data reported a response rate of more than 60% in this subset of patients (Jädersten & Hellström-Linderberg, 2009). Nevertheless this effective treatment frequently induce severe (World Health Organization grade III–IV) neutropenia (55% of treated patients) and thrombocytopenia (44% of patients) at least during the initial 2–3 months. Another problem to be considered is the high cost of this standard therapy, as recently highlighted (Stone, 2009). One way to reduce toxicity has been reported by lowering the standard dose from 10 to 5 mg/d for 21 d (Giagounidis et al, 2008), but this schedule did not substantially affect the cost, because of the tablets’ unit price. On this particular issue we would like to report our pivotal experience in six patients treated with lenalidomide at 10 mg on alternative days for 21 d every 28 d. Our intent was to maintain the same efficacy, reduce treatment-related toxicity and also lower the cost of treatment. Moreover, there are no published data to date about the target plasma concentration of lenalidomide required to effectively inhibit the del 5q clone (Kelaidi et al, 2008). Patients signed an informed consent before starting this modified drug schedule. Their characteristics and response to lenalidomide are summarized in Table I. All six patients were blood transfusion-dependent (Haemoglobin level ranging from 70 to 85 g/l) after failing erythropoietin (EPO). Blood values included also mild leucopenia (range white blood cell count ranged from 2 to 4 · 10/l) and a normal/slightly high platelet count (range 280 to 450 · 10/l). All patients started lenalidomide with a normal creatinine clearance (90– 125 ml/min) and no serological abnormal value, apart from an elevated ferritin level (range 520–1900 lg/l). No other treatment except EPO and red cells support was previously given to the patients. After receiving lenalidomide at 10 mg/d on alternative days for 21 d every 28 d, all six patients achieved transfusion independence within 3 months (three patients) and within 4 months (three patients) from starting the treatment, respectively. At the time of this report the last haemoglobin level of the patients ranged from 110 to 143 g/l after a median time of treatment of 11 months (range 6–14 months) (Table I). Five out of 6 patients were evaluated for cytogenetic response (CyR): 2/5 patients achieved a complete cytogenetic response (CCyR) after 7 and 6 months of treatment, respectively, while 3/5 patients obtained a partial CyR (with residual 5qmitosis ranging from 20% to 25%) after 7, 8 and 9 months of treatment, respectively. CyR was confirmed in all patients at last follow-up. Regarding drug-related toxicity, only 1/6 (17%) patients experienced a grade 3 thrombocytopenia, while 2/6 (33%) patients had grade 3 neutropenia, which needed a short course of granulocyte colony-stimulating factor treatment. None of the patients had fever or infection and no further dose reduction was applied. To our knowledge, this is the first report suggesting that 10 mg lenalidomide on alternative days is as effective and

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.

Residual peripheral blood CD26+leukemic stem cells in chronic myeloid leukemia patients during TKI therapy and during treatment-free remission

Chronic myeloid leukemia (CML) patients in sustained “deep molecular response” may stop TKI treatment without disease recurrence; however, half of them lose molecular response shortly after TKI withdrawing. Well-defined eligibility criteria to predict a safe discontinuation up-front are still missing. Relapse is probably due to residual quiescent TKI-resistant leukemic stem cells (LSCs) supposedly transcriptionally low/silent and not easily detectable by BCR-ABL1 qRT-PCR. Bone marrow Ph+ CML CD34+/CD38− LSCs were found to specifically co-express CD26 (dipeptidylpeptidase-IV). We explored feasibility of detecting and quantifying CD26+ LSCs by flow cytometry in peripheral blood (PB). Over 400 CML patients (at diagnosis and during/after therapy) entered this cross-sectional study in which CD26 expression was evaluated by a standardized multiparametric flow cytometry analysis on PB CD45+/CD34+/CD38− stem cell population. All 120 CP-CML patients at diagnosis showed measurable PB CD26+ LSCs (median 19.20/μL, range 0.27–698.6). PB CD26+ LSCs were also detectable in 169/236 (71.6%) CP-CML patients in first-line TKI treatment (median 0.014 cells/μL; range 0.0012–0.66) and in 74/112 (66%), additional patients studied on treatment-free remission (TFR) (median 0.015/μL; range 0.006–0.76). Notably, no correlation between BCR-ABL/ABLIS ratio and number of residual LSCs was found both in patients on or off TKIs. This is the first evidence that “circulating” CML LSCs persist in the majority of CML patients in molecular response while on TKI treatment and even after TKI discontinuation. Prospective studies evaluating the dynamics of PB CD26+ LSCs during TKI treatment and the role of a “stem cell response” threshold to achieve and maintain TFR are ongoing.

FLT3 Inhibitors in the Management of Acute Myeloid Leukemia

In recent years there has been a great improvement in molecular characterization of acute myeloid leukemia (AML) allowing the stratification of patients in different rate of risk. Patients with FLT3 mutated AML have poor prognosis because of resistance to induction chemotherapy or early relapse. Several first and second generation molecules, able to inhibit FLT3 signaling have been developed and many single agent or combination studies are ongoing. Of these, quizartinib seems to have the best clinical activity. Unfortunately, resistance to FLT3 inhibitors has been observed and many scientists are currently investigating new strategy to restore sensitivity to FLT3 inhibitors.