[History of chronic myeloid leukemia: a paradigm in the treatment of cancer]. / Historique de la leucémie myéloïde chronique : un paradigme de traitement du cancer.

During two centuries, advances in medicine and medical research have helped to understand the pathophysiology of chronic myelogenous leukemia (CML). This hematologic malignancy is a unique model of oncogenesis where a single molecular hit, causing cell proliferation and survival, was identified. The chromosomal abnormality first highlighted by P. Nowell and D. Hungerford in 1960, and characterized as the reciprocal translocation t(9;22)(q34;q11), the Philadelphia chromosome, discovered in leukemic cells, by J. Rowley in 1973. At the end of the 20th century, the contribution of molecular biology techniques was crucial by the discovery of the BCR-ABL1 hybrid oncogene derived from the t(9;22), responsible for the translation of an aberrant protein tyrosine kinase. This BCR-ABL1 kinase deregulates signaling pathways that control normal cell cycle and survival in primitive hematopoietic cells and is thus responsible for malignant cell accumulation observed in CML. It was then only necessary to develop a targeted treatment adapted to this molecular hit. Recently, tyrosine kinase inhibitors, by their specific inhibitory activity of BCR-ABL, have revolutionized the treatment of CML, allowing rates of haematological, cytogenetic and molecular responses never seen to date, and has significantly improved the overall survival and the quality of life of patients.

A phase 2 trial of ponatinib in Philadelphia chromosome-positive leukemias.

BACKGROUND: Ponatinib is a potent oral tyrosine kinase inhibitor of unmutated and mutated BCR-ABL, including BCR-ABL with the tyrosine kinase inhibitor-refractory threonine-to-isoleucine mutation at position 315 (T315I). We conducted a phase 2 trial of ponatinib in patients with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL). METHODS: We enrolled 449 heavily pretreated patients who had CML or Ph-positive ALL with resistance to or unacceptable side effects from dasatinib or nilotinib or who had the BCR-ABL T315I mutation. Ponatinib was administered at an initial dose of 45 mg once daily. The median follow-up was 15 months. RESULTS: Among 267 patients with chronic-phase CML, 56% had a major cytogenetic response (51% of patients with resistance to or unacceptable side effects from dasatinib or nilotinib and 70% of patients with the T315I mutation), 46% had a complete cytogenetic response (40% and 66% in the two subgroups, respectively), and 34% had a major molecular response (27% and 56% in the two subgroups, respectively). Responses were observed regardless of the baseline BCR-ABL kinase domain mutation status and were durable; the estimated rate of a sustained major cytogenetic response of at least 12 months was 91%. No single BCR-ABL mutation conferring resistance to ponatinib was detected. Among 83 patients with accelerated-phase CML, 55% had a major hematologic response and 39% had a major cytogenetic response. Among 62 patients with blast-phase CML, 31% had a major hematologic response and 23% had a major cytogenetic response. Among 32 patients with Ph-positive ALL, 41% had a major hematologic response and 47% had a major cytogenetic response. Common adverse events were thrombocytopenia (in 37% of patients), rash (in 34%), dry skin (in 32%), and abdominal pain (in 22%). Serious arterial thrombotic events were observed in 9% of patients; these events were considered to be treatment-related in 3%. A total of 12% of patients discontinued treatment because of an adverse event. CONCLUSIONS: Ponatinib had significant antileukemic activity across categories of disease stage and mutation status. (Funded by Ariad Pharmaceuticals and others; PACE ClinicalTrials.gov number, NCT01207440 .).

Biology of CML stem cells: the basis for clinical heterogeneity?

Although chronic myeloid leukemia (CML) is now defined on the basis of the presence of the BCR-ABL1 fusion gene, which may or may not be the initial genetic event that triggers the inappropriate expansion of the myeloid cell mass, CML, similar to other leukemias, is in fact clinically heterogeneous. The biological basis for this heterogeneity is unknown. Here, we summarize some of the data illustrating this heterogeneity and speculate about possible mechanisms that may cause it. It could, for example, be intrinsic in the leukemia stem cell or could be related to some aspect of the patient's response to the leukemia.

Prognostic factors for outcomes in allogeneic transplantation for CML in the imatinib era: a CIBMTR analysis.

Allogeneic hematopoietic SCT is an effective treatment in accelerated (AP) or blast phase (BP) CML. Imatinib (IM) has transient but significant activity in advanced phases of CML, which may permit early allografting for responding patients. To identify prognostic factors in allograft recipients previously treated with IM, we analyzed 449 allogeneic hematopoietic SCTs performed from 1999 to 2004 in advanced-phase CML, using the data reported to the Center for International Blood and Marrow Transplant Research. CML patients in second chronic phase (CP2, n=184), AP (n=185) and BP (n=80) received HLA-identical sibling (27%), related (3%), or matched or mismatched unrelated donor (70%), peripheral blood (47%) or BM (53%) hematopoietic SCT after myeloablative (78%) or non-myeloablative (22%) conditioning. In all, 52% in CP2, 49% in AP and 46% in BP received IM before hematopoietic SCT. Disease-free survival was 35-40% for CP2, 26-27% for AP and 8-11% for BP. Cumulative incidence of acute and chronic GVHD and TRM were not affected by the stages of CML or pre-hematopoietic SCT IM exposure. Multivariate analyses showed that conventional prognostic indicators remain the strongest determinants of transplant outcomes. In conclusion, there are no new prognostic indicators of the outcomes of allogeneic hematopoietic SCT for advanced-phase CML in the IM era.

KIR2DS1 genotype predicts for complete cytogenetic response and survival in newly diagnosed chronic myeloid leukemia patients treated with imatinib.

Natural killer (NK) cells are expanded in chronic myeloid leukemia (CML) patients on tyrosine kinase inhibitors (TKI) and exert cytotoxicity. The inherited repertoire of killer immunoglobulin-like receptors (KIR) may influence response to TKI. We investigated the impact of KIR-genotype on outcome in 166 chronic phase CML patients on first-line imatinib treatment. We validated our findings in an independent patient group. On multivariate analysis, KIR2DS1 genotype (RR=1.51, P=0.03) and Sokal risk score (low-risk RR=1, intermediate-risk RR=1.53, P=0.04, high-risk RR=1.69, P=0.034) were the only independent predictors for failure to achieve complete cytogenetic response (CCyR). Furthermore, KIR2DS1 was the only factor predicting shorter progression-free (PFS) (RR=3.1, P=0.03) and overall survival (OS) (RR=2.6, P=0.04). The association between KIR2DS1 and CCyR, PFS and OS was validated by KIR genotyping in 174 CML patients on first-line imatinib in the UK multi-center SPIRIT-1 trial; in this cohort, KIR2DS1(+) patients had significantly lower 2-year probabilities of achieving CCyR (76.9 vs 87.9%, P=0.003), PFS (85.3 vs 98.1%, P=0.007) and OS (94.4 vs 100%, P=0.015) than KIR2DS1(-) patients. The impact of KIR2DS1 on CCyR was greatest when the ligand for the corresponding inhibitory receptor, KIR2DL1, was absent (P=0.00006). Our data suggest a novel role for KIR-HLA immunogenetics in CML patients on TKI.

Diverging effects of HLA-DPB1 matching status on outcome following unrelated donor transplantation depending on disease stage and the degree of matching for other HLA alleles.

Disease stage and recipient/donor human leukocyte antigen (HLA) matching are important determinants of outcome in transplantation using volunteer-unrelated donors (VUD). Matching for HLA-A, -B, -C, -DRB1, -DQB1 is beneficial, whereas the importance of DPB1 matching is more controversial. The impact of HLA matching status may differ dependent on disease stage. We investigated the outcome according to the degree of HLA matching at 6 loci, in 488 recipients of predominantly T-cell depleted bone marrow VUD transplants for leukaemia. Survival was significantly better in 12/12-matched transplants in those with early leukaemia (5 years: 63 versus 41% in 10/10 matched, P=0.006), but not late stage disease. Conversely, within the HLA-mismatched group (< or =9/10), there was a significant survival advantage to DPB1 mismatching (5 years: 39 versus 21% in DPB1 matched, P=0.008), particularly in late leukaemia (P=0.01), persisting in multivariate analysis (odds ratio 0.478; 95% confidence interval 0.30, 0.75; P=0.001). These novel findings suggest that the best outcome for patients with early leukaemia, with a 10/10-matched donor, is achieved by matching for DPB1. Conversely, our results suggest that in patients receiving an HLA-mismatched graft, the outcome is significantly better if they are also mismatched for DPB1. We recommend validation of these results in independent datasets.

Chronic myeloproliferative diseases with and without the Ph chromosome: some unresolved issues.

Ph-positive chronic myeloid leukemia (CML) and Ph-negative chronic myeloproliferative diseases (MPDs), characterized in many cases by the presence of the JAK2(V617F) mutation, have many features in common and yet also show fundamental differences. In this review, we pose five discrete and related questions relevant to both categories of hematological malignancy, namely: What are the mechanisms that underlie disease progression from a relatively benign or chronic phase? By what therapeutic methods might one target residual leukemia stem cells in CML? Is JAK2(V617F) the original molecular event in MPD? What epigenetic events must have a role in dictating disease phenotype in MPDs? And finally, Will the benefits conferred by current or future JAK2(V617F) inhibitors equal or even surpass the clinical success that has resulted from the use of tyrosine kinase inhibitors in CML? These and others questions must be addressed and in some cases should be answered in the foreseeable future.

Six-year follow-up of patients receiving imatinib for the first-line treatment of chronic myeloid leukemia.

Imatinib mesylate is considered standard of care for first-line treatment of chronic phase chronic myeloid leukemia (CML-CP). In the phase III, randomized, open-label International Randomized Study of Interferon vs STI571 (IRIS) trial, previously untreated CML-CP patients were randomized to imatinib (n=553) or interferon-alpha (IFN) plus cytarabine (n=553). This 6-year update focuses on patients randomized to receive imatinib as first-line therapy for newly diagnosed CML-CP. During the sixth year of study treatment, there were no reports of disease progression to accelerated phase (AP) or blast crisis (BC). The toxicity profile was unchanged. The cumulative best complete cytogenetic response (CCyR) rate was 82%; 63% of all patients randomized to receive imatinib and still on study treatment showed CCyR at last assessment. The estimated event-free survival at 6 years was 83%, and the estimated rate of freedom from progression to AP and BC was 93%. The estimated overall survival was 88% -- or 95% when only CML-related deaths were considered. This 6-year update of IRIS underscores the efficacy and safety of imatinib as first-line therapy for patients with CML.

A new rapid and sensitive assay for detecting the T315I BCR-ABL kinase domain mutation in chronic myeloid leukaemia.

A significant minority of chronic myeloid leukaemia patients eventually develop resistance to imatinib, often as a result of point mutations within the BCR-ABL kinase domain. Second-line tyrosine kinase inhibitors (TKIs) are effective against mutations that confer imatinib resistance; however, the T315I BCR-ABL mutant has proved resistant to all available TKIs. An assay facilitating early identification of BCR-ABL(T315I) would therefore aid in identifying high-risk patients who may benefit from alternative therapy. This report describes the development of a sensitive T315I mutation detection methodology based on real-time PCR with self-probing fluorescent primers. The technique demonstrated complete concordance with direct sequencing, correctly identifying 34 T315I-positive samples from a total of 61 samples screened. In a limiting dilution assay, the mutated clone was detectable to a level of 1% of total cells. The data show that Scorpions PCR enables rapid screening for BCR-ABL(T315I) in chronic myeloid leukaemia patients and is appropriate for use in a clinical setting.

Hematopoietic stem cells and progenitors of chronic myeloid leukemia express leukemia-associated antigens: implications for the graft-versus-leukemia effect and peptide vaccine-based immunotherapy.

The cure of chronic myeloid leukemia (CML) patients following allogeneic stem cell transplantation (SCT) is attributed to graft-versus-leukemia (GVL) effects targeting alloantigens and/or leukemia-associated antigens (LAA) on leukemia cells. To assess the potential of LAA-peptide vaccines in eliminating leukemia in CML patients, we measured WT1, PR3, ELA2 and PRAME expression in CD34+ progenitor subpopulations in CML patients and compared them with minor histocompatibility antigens (mHAgs) HA1 and SMCY. All CD34+ subpopulations expressed similar levels of mHAgs irrespective of disease phase, suggesting that in the SCT setting, mHAgs are the best target for GVL. Furthermore, WT1 was consistently overexpressed in advanced phase (AdP) CML in all CD34+ subpopulations, and mature progenitors of chronic phase (CP) CML compared to healthy individuals. PRAME overexpression was limited to more mature AdP-CML progenitors only. Conversely, only CP-CML progenitors had PR3 overexpression, suggesting that PR1-peptide vaccines are only appropriate in CP-CML. Surface expression of WT1 protein in the most primitive hematopoietic stem cells in AdP-CML suggest that they could be targets for WT1 peptide-based vaccines, which in combination with PRAME, could additionally improve targeting differentiated progeny, and benefit patients responding suboptimally to tyrosine kinase inhibitors, or enhance GVL effects in SCT patients.

Regional differences in the pituitary distribution of luteinizing hormone in the gonadectomized and proestrous female rat.

Previous data have shown that regional differences in the presence of anterior pituitary luteinizing hormone (LH) generally correlate with the comparable disparities in distribution of gonadotropes throughout the gland. In female rats, the differences are apparent over the estrous cycle, but are more prominent during the hours preceding the proestrus surge of LH. The current experiments examined (1) if such regional disparities are present throughout the surge window, (2) if differences are mirrored by release of LH in vitro and (3) if the appearance of regional differences is altered in ovariectomized females. Results showed that a comparative elevation in the rostral portion of the pituitary during the pre-surge period diminishes and finally disappears concurrent with the rise in circulating LH. This increase in rostral LH concentrations is reflected in this region by a comparable effect in vitro on stimulated LH secretion from pituitary fragments, although the effect is somewhat diminished by referencing release against tissue concentrations of LH present in a contralateral rostral fragment. Ovariectomies conducted at 1500h on proestrus, at a time when a significant regional difference has faded, resulted in a prompt increase in LH across all areas of the pituitary, and the emergence of a marked augmentation in rostral concentrations over the ensuing 72h. The effect was not seen when ovariectomies were performed on estrus. These data show that, while a regional disparity in anterior pituitary LH is present as circulating concentrations of estradiol rise prior to the LH surge, the removal of this steroid feedback at a time when LH synthesis is normally amplified accentuates the difference between the rostral region and other areas of the pituitary.

Factors for graft-versus-host disease after donor lymphocyte infusions with an escalating dose regimen: lack of association with cell dose.

We investigated the risk factors for graft-versus-host disease (GVHD) in 82 patients treated with donor lymphocyte infusions (DLI) using an escalating dose regimen for chronic myeloid leukaemia in relapse following conventional allografting. Two factors emerged as predictors of both acute and chronic GVHD: the infusion of male recipients with lymphocytes from a female donor and the interval between transplant and last DLI, but only the first remained significant at multivariate analysis. Surprisingly, lymphocyte dose did not influence the incidence of GVHD. Our results suggest that DLI can be given in large cell doses without increasing the risk of GVHD.

Response to donor lymphocyte infusions for chronic myeloid leukemia is dose-dependent: the importance of escalating the cell dose to maximize therapeutic efficacy.

Donor lymphocyte infusions (DLI) are an effective treatment for patients with chronic myeloid leukemia (CML) in relapse after allografting but the optimal cell dose has yet to be identified. To address this question, we investigated the factors affecting the dose required to achieve remission (effective cell dose, (ECD)) in 81 patients treated with an escalating dose regimen. The overall proportion of patients who achieved a molecular remission was 88%. The cumulative proportion of remitters increased significantly at each dose level. With a CD3(+) cell dose < or =10(7)/kg, 56% of patients in molecular/cytogenetic relapse obtained molecular remission, whereas only 20% of those in hematologic relapse did so. At the same cell dose, 58% of patients who received lymphocytes from volunteer unrelated donors achieved remission, as compared to 29% of those who received DLI from sibling donors. We conclude that the response to DLI is dose-dependent and that the ECD is influenced by the quantity and phase of CML at relapse and degree of donor/recipient histocompatibility.