Nilotinib.

With imatinib still being linked to the breakthrough in CML therapy and probably being the most prescribed drug, second-generation TKIs are increasingly gaining importance. Showing higher response rates while not leading to more adverse events, nilotinib has become an attractive option in the first-line treatment of chronic-phase chronic myeloid leukemia. By reaching deep and long-lasting molecular remissions, discontinuation of TKIs is becoming one of the central topics of future CML therapy. Stopping nilotinib seems safe and provides a stable remission in about half of the eligible patients, though long-term data are still missing.

Nilotinib.

Targeted therapy of Philadelphia chromosome-positive chronic myeloid leukemia (CML) using the tyrosine kinase inhibitor imatinib mesylate has been one of the most striking achievements in modern cancer medicine. However, while imatinib can establish long-term remission in many cases, resistance to or intolerance of imatinib is eventually experienced by a substantial number of patients. Subsequent advances have led to the development of novel tyrosine kinase inhibitors (TKIs). One such inhibitor, nilotinib, was rationally designed to increase its affinity and specificity for the oncogenic tyrosine kinase Bcr-Abl compared with imatinib and has been shown to be effective after imatinib failure. Recently, nilotinib has been shown to be more effective when used as first-line therapy of chronic phase CML.

Clinical cardiac safety profile of nilotinib.

BACKGROUND: Nilotinib is a second-generation tyrosine kinase inhibitor with significant efficacy as first- or second-line treatment in patients with chronic myeloid leukemia. Despite preclinical evidence indicating a risk of prolongation of the QT interval, which was confirmed in clinical trials, detailed information on nilotinib's cardiac safety profile is lacking. DESIGN AND METHODS: Here, we retrospectively assessed cardiovascular risk factors in 81 patients who were being or had previously been treated with nilotinib therapy and evaluated cardiovascular parameters by longitudinal monitoring of the QT interval and left ventricular ejection fraction. Detailed information on the occurrence and management of defined cardiac adverse events was extracted. RESULTS: The median duration of nilotinib therapy was 26 months (range, 1-72). The median QT interval at baseline was 413 msec (range, 368-499 msec). During follow-up, the median QT was not significantly different from the baseline value at any time-point. Sixteen of 81 patients (20%) had new electrocardiographic changes. Cardiac function, as assessed by measurement of left ventricular ejection fraction, did not change significantly from baseline at any time-point. During a median follow-up of 44 months (range, 2-73), seven patients (9%), all of whom had received prior imatinib therapy, developed 11 clinical cardiac adverse events requiring treatment. The median time from the start of nilotinib therapy to an event was 14.5 months (range, 2-68). Five of seven patients were able to continue nilotinib therapy with only one brief interruption. CONCLUSIONS: Whereas new electrocardiographic abnormalities were recorded in 20% of all patients and some of them developed severe or even life-threatening coronary artery disease, QT prolongation, changes in left ventricular ejection fraction, and clinical cardiac adverse events were uncommon in patients treated with nilotinib.

Tyrosine kinase inhibitors noncompetitively inhibit MCT8-mediated iodothyronine transport.

CONTEXT: Tyrosine kinase inhibitors (TKI) are used for the treatment of various cancers. Case reports and clinical trials have reported abnormal thyroid function tests (TFT) after treatment with sunitinib, imatinib, sorafenib, dasatinib, and nilotinib. An increased requirement for levothyroxine was reported in thyroidectomized patients during TKI treatment. OBJECTIVE: We hypothesized that abnormal TFT are compatible with inhibition of thyroid hormone (TH) transporters and subsequently reduced pituitary-TH feedback. Monocarboxylate transporter 8 (MCT8) is a TH transmembrane transporter in brain, pituitary, and other organs. MCT8 mutation leads to abnormal TFT in patients and respective mouse models. We tested whether TKI are able to inhibit MCT8-mediated TH uptake into cells. DESIGN: Madin-Darby-canine kidney (MDCK1) cells stably expressing human MCT8 were exposed in vitro to TKI at increasing concentrations, and MCT8-mediated [(125)I]T(3) uptake and efflux were measured. The mode of inhibition was determined. RESULTS: TKI exposure dose-dependently inhibited MCT8-dependent T(3) and T(4) uptake. IC(50) values for sunitinib, imatinib, dasatinib, and bosutinib ranged from 13-38 µm, i.e. similar to the Michaelis-Menten constant K(m) for T(3) and T(4), 4 and 8 µm, respectively. Kinetic experiments revealed a noncompetitive mode of inhibition for all TKI tested. CONCLUSIONS: Partial inhibition by TKI of pituitary or hypothalamic TH feedback may increase TSH or increase the levothyroxine requirement of thyroidectomized patients. It is still possible that other mechanisms contribute to TKI-mediated impairments of TFT, e.g. altered metabolism of TH. Bosutinib was not previously reported to alter TFT.

Thyroid dysfunction caused by second-generation tyrosine kinase inhibitors in Philadelphia chromosome-positive chronic myeloid leukemia.

BACKGROUND: Thyroid dysfunction is a well-known adverse effect of first-generation tyrosine kinase inhibitors (TKIs), like sunitinib. The aim of this study was to investigate the effect of second-generation TKIs on thyroid function. METHODS: We retrospectively assessed the effect of the first-generation TKI imatinib and the second-generation TKI nilotinib and dasatinib on thyroid function tests in 73 Philadelphia chromosome-positive (Ph-positive) chronic myeloid leukemia patients. RESULTS: Overall, 33 of 73 (45%) had one or more thyroid function test abnormalities during follow-up. Hypothyroidism or hyperthyroidism were found in 18 of 73 (25%) and 21 of 73 (29%) cases after a median of 6 and 22 weeks, respectively. In most patients (29 of 39, 74%) thyroid dysfunction was transient without clinical symptoms. Therapy of hypo-/hyperthyroidism was required in three patients. Thyroid dysfunction never resulted in the discontinuation of TKI therapy. Under treatment with imatinib, nilotinib, and dasatinib, thyroid abnormalities were detected in 25%, 55%, and 70%, respectively. Four of 55 patients (7%) treated with nilotinib had evidence for an autoimmune thyroiditis (antibody positive in 3 of 4 patients) with an episode of hyperthyroidism preceding hypothyroidism. CONCLUSIONS: Thyroid dysfunction is a common adverse event with second-generation TKI therapy in patients with Ph-positive chronic myeloid leukemia. Although the mechanism is still unclear, the high frequency of thyroid abnormalities, including autoimmune thyroiditis, warrants regular and long-term monitoring of thyroid function in these patients.

New developments in tyrosine kinase inhibitor therapy for newly diagnosed chronic myeloid leukemia.

The biology of chronic myeloid leukemia (CML) has enabled pioneering studies with targeted therapies. BCR-ABL inhibition with imatinib results in high levels of efficacy in patients with newly diagnosed CML in chronic phase (CP), but an estimated 35% of patients could benefit from more effective treatment. Several novel treatment strategies are being investigated in newly diagnosed CML-CP. These strategies include upfront treatment with next-generation tyrosine kinase inhibitors, such as dasatinib, nilotinib, or bosutinib, which also target BCR-ABL but with increased in vitro potency compared with imatinib, and possibly a reduced potential for resistance. Recent in vitro studies have shown that short-term exposure to dasatinib or continuous exposure to imatinib result in equivalent levels of apoptosis, indicating that potent intermittent inhibition is a successful strategy for improving dasatinib tolerability. Modified imatinib regimens are also being investigated in newly diagnosed CML-CP, including higher doses and combination with alternative classes of agents, such as interferon. Existing data suggest that both newer agents and combination approaches can improve treatment responses compared with standard imatinib treatment, although further data are needed, particularly from ongoing phase 3 trials, before the standard of care is revised.

Impact of additional chromosomal aberrations and BCR-ABL kinase domain mutations on the response to nilotinib in Philadelphia chromosome-positive chronic myeloid leukemia.

BACKGROUND: Additional chromosomal aberrations in Philadelphia chromosome-positive chronic myeloid leukemia are non-random and strongly associated with disease progression, but their prognostic impact and effect on treatment response is not clear. Point mutations in the BCR-ABL kinase domain are probably the most common mechanisms of imatinib resistance. DESIGN AND METHODS: We assessed the influence of additional chromosomal aberrations and BCR-ABL kinase domain mutations on the response to the second-generation tyrosine kinase inhibitor nilotinib after imatinib-failure. Standard cytogenetic analysis of metaphases was performed to detect additional chromosomal aberrations and the BCR-ABL kinase domain was sequenced to detect point mutations. RESULTS: Among 53 patients with a median follow-up of 16 months, of whom 38, 5 and 10 were in chronic phase, accelerated phase and blast crisis, respectively, 19 (36%) had additional chromosomal aberrations and 20 (38%) had BCR-ABL kinase domain mutations. The 2-year overall survival rate of all patients with-out additional chromosomal aberrations (89%) was higher than that of patients with such aberrations (54%) (P=0.0025). Among patients with chronic phase disease, overall survival at 2 years was 100% and 62% for patients without or with additional chromosomal aberrations, respectively (P=0.0024). BCR-ABL kinase domain mutations were associated with lower remission rates in response to nilotinib, with 9 of 20 (45%) of these patients achieving a major cytogenetic remission as compared to 26 of 33 (79%) patients without mutations (P<0.05). However, overall survival was not affected by BCR-ABL kinase domain mutations. CONCLUSIONS: Whereas BCR-ABL kinase domain mutations may confer more specific resistance to nilotinib, which will predominantly affect response rates, the presence of additional chromosomal aberrations may reflect genetic instability and, therefore, intrinsic aggressiveness of the disease which will be less amenable to subsequent alternative treatments and thus negatively affect overall survival. Conventional cytogenetic analyses remain mandatory during follow-up of patients with chronic myeloid leukemia under tyrosine kinase inhibitor therapy.

Allogeneic hematopoietic stem cell transplantation for adult acute lymphocytic leukemia.

Allogeneic hematopoietic stem cell transplantation (alloHCT) is the single most potent treatment modality to prevent relapse in adults with acute lymphocytic leukemia, but its optimal use and timing remains a matter of intense debate and research. There is general agreement that patients with clinical features of high risk for relapse should undergo alloHCT in first complete remission. However, newer studies suggest that even patients without these risk factors may benefit. Monitoring of minimal residual disease may improve risk stratification and may complement or replace conventional risk features. Prognosis in relapsed and refractory patients is dismal, and alloHCT should be performed as soon as possible. AlloHCT also offers the only reasonable chance for cure in Philadelphia chromosome-positive acute lymphocytic leukemia; the role of imatinib is not yet clearly defined. Recent developments in unrelated-donor transplantation and reduced-intensity conditioning allow the beneficial effects of alloHCT to reach a considerably wider patient population.

Organ-derived dendritic cells have differential effects on alloreactive T cells.

Dendritic cells (DCs) are considered critical for the induction of graft-versus-host disease (GVHD) after bone marrow transplantation (BMT). In addition to their priming function, dendritic cells have been shown to induce organ-tropism through induction of specific homing molecules on T cells. Using adoptive transfer of CFSE-labeled cells, we first demonstrated that alloreactive T cells differentially up-regulate specific homing molecules in vivo. Host-type dendritic cells from the GVHD target organs liver and spleen or skin- and gut-draining lymph nodes effectively primed naive allogeneic T cells in vitro with the exception of liver-derived dendritic cells, which showed less stimulatory capacity. Gut-derived dendritic cells induced alloreactive donor T cells with a gut-homing phenotype that caused increased GVHD mortality and morbidity compared with T cells stimulated with dendritic cells from spleen, liver, and peripheral lymph nodes in an MHC-mismatched murine BMT model. However, in vivo analysis demonstrated that the in vitro imprinting of homing molecules on alloreactive T cells was only transient. In conclusion, organ-derived dendritic cells can efficiently induce specific homing molecules on alloreactive T cells. A gut-homing phenotype correlates with increased GVHD mortality and morbidity after murine BMT, underlining the importance of the gut in the pathophysiology of GVHD.

IFN-gamma and Fas ligand are required for graft-versus-tumor activity against renal cell carcinoma in the absence of lethal graft-versus-host disease.

To determine the mechanisms of graft-versus-tumor (GVT) activity in the absence of graft-versus-host disease (GVHD) against a solid tumor, we established two allogeneic bone marrow transplantation models with a murine renal cell carcinoma (RENCA). The addition of 0.3 x 10(6) donor CD8(+) T cells to the allograft increased the survival of tumor-bearing mice without causing GVHD. The analysis of CD8(+) T cells deficient in cytotoxic molecules demonstrated that anti-RENCA activity is dependent on IFN-gamma and Fas ligand (FasL), but does not require soluble or membrane-bound TNF-alpha, perforin, or TRAIL. Recipients of IFN-gamma(-/-) CD8(+) T cells are unable to reject RENCA compared with recipients of wild-type CD8(+) T cells and, importantly, neither group develops severe GVHD. IFN-gamma(-/-) CD8(+) T cells derived from transplanted mice are less able to kill RENCA cells in vitro, while pretreatment of RENCA cells with IFN-gamma enhances class I and FasL expression and rescues the lytic capacity of IFN-gamma(-/-) CD8(+) T cells. These results demonstrate that the addition of low numbers of selected donor CD8(+) T cells to the allograft can mediate GVT activity without lethal GVHD against murine renal cell carcinoma, and this GVT activity is dependent on IFN-gamma and FasL.

Absence of donor T-cell-derived soluble TNF decreases graft-versus-host disease without impairing graft-versus-tumor activity.

Tumor necrosis factor (TNF) plays an important role in graft-versus-host disease (GVHD) and graft-versus-tumor (GVT) activity after allogeneic bone marrow transplantation (allo-BMT). TNF can be expressed in a membrane-bound form (memTNF) and as a soluble (solTNF) molecule after being cleaved by the TNF-alpha converting enzyme (TACE). To study the contribution of donor T-cell-derived memTNF versus solTNF in GVHD and GVT, we used mice containing a noncleavable allele in place of endogenous TNF (memTNF(Delta/Delta)) as donors in murine BMT models. Recipients of memTNF T cells developed significantly less GVHD than recipients of wild-type (wt) T cells. In contrast, GVT activity mediated by memTNF T cells remained intact, and alloreactive memTNF T cells showed no defects in proliferation, activation, and cytotoxicity. These data suggest that suppressing the secretion of solTNF by donor T cells significantly decreases GVHD without impairing GVT activity.

Adoptive transfer of T-cell precursors enhances T-cell reconstitution after allogeneic hematopoietic stem cell transplantation.

Immunoincompetence after allogeneic hematopoietic stem cell transplantation (HSCT) affects in particular the T-cell lineage and is associated with an increased risk for infections, graft failure and malignant relapse. To generate large numbers of T-cell precursors for adoptive therapy, we cultured mouse hematopoietic stem cells (HSCs) in vitro on OP9 mouse stromal cells expressing the Notch-1 ligand Delta-like-1 (OP9-DL1). We infused these cells, together with T-cell-depleted mouse bone marrow or purified HSCs, into lethally irradiated allogeneic recipients and determined their effect on T-cell reconstitution after transplantation. Recipients of OP9-DL1-derived T-cell precursors showed increased thymic cellularity and substantially improved donor T-cell chimerism (versus recipients of bone marrow or HSCs only). OP9-DL1-derived T-cell precursors gave rise to host-tolerant CD4+ and CD8+ populations with normal T-cell antigen receptor repertoires, cytokine secretion and proliferative responses to antigen. Administration of OP9-DL1-derived T-cell precursors increased resistance to infection with Listeria monocytogenes and mediated significant graft-versus-tumor (GVT) activity but not graft-versus-host disease (GVHD). We conclude that the adoptive transfer of OP9-DL1-derived T-cell precursors markedly enhances T-cell reconstitution after transplantation, resulting in GVT activity without GVHD.

Absence of beta7 integrin results in less graft-versus-host disease because of decreased homing of alloreactive T cells to intestine.

The alpha4beta7 integrin plays a central role in the homing of T cells to the gut. We hypothesized that absence of the beta7 subunit would result in a reduction of intestinal graft-versus-host disease (GVHD) and an improvement in overall GVHD morbidity and mortality in recipients of hematopoietic stem cell transplantation (HSCT). Analysis of alloreactive beta7-/- T cells showed intact activation, proliferation, cytokine production, and cytotoxicity. However, recipients of beta7-/- donor T cells in murine HSCT models experienced less GVHD morbidity and mortality than recipients of wild-type (WT) T cells, associated with a decrease in donor T-cell infiltration of the liver and intestine and with an overall significant decrease in hepatic and intestinal GVHD. In graft-versus-tumor (GVT) experiments, we demonstrated intact or even enhanced GVT activity of beta7-/- donor T cells. In conclusion, beta7-/- donor T cells caused less GVHD morbidity and mortality than WT donor T cells because of selectively decreased T-cell infiltration of the liver and intestines. Our data suggest that strategies to target the beta7 integrin have the clinical potential to alleviate or prevent GVHD while sparing or potentiating GVT activity.

Long-term follow-up of gastric MALT lymphoma after Helicobacter pylori eradication.

PURPOSE: Cure of infection induces remissions in most patients with early stage Helicobacter pylori- (Hp) positive gastric MALT (mucosa-associated lymphoid tissue) lymphoma (GML). We tracked the long-term stability of remissions in this prospective, multicenter trial. PATIENTS AND METHODS: In 120 patients with stage I(1E) disease, we performed sequential endoscopic-bioptic follow-up after Hp eradication and polymerase chain reaction of the rearranged immunoglobulin heavy chain gene. The status of t(11;18) was assessed in 65 patients. RESULTS: Median follow-up was 75 months (range, one to 116). Five-year survival was 90%. Eighty percent of patients (96 of 120) achieved complete histologic remission (CR). Eighty percent of CRs are in continuous complete histologic remission (CCR). Three percent of CR patients (three of 96) relapsed and were referred for alternative treatment. Seventeen percent of CR patients (16 of 96) showed histologic residual disease (RD) during follow-up; a watch-and-wait strategy was applied, and all entered into a second CR. After a median follow-up of 63 months, 14 of 52 analyzed patients reaching CR showed ongoing B-cell monoclonality. Fifteen percent of GMLs were t(11;18) positive. Both t(11;18) and ongoing monoclonality were associated with a significantly higher risk for no response or relapse (P =.004, P =.007), but also present in patients in CCR. Early gastric cancer was diagnosed in three cases during follow-up. CONCLUSION: Cure of Hp infection results in CCR in most patients. Histologic RD, B-cell monoclonality, and t(11;18) were present in a considerable number of CR patients. A watch-and-wait strategy is justified when close follow-up is guaranteed.

CCR2 is required for CD8-induced graft-versus-host disease.

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). Migration of donor-derived T cells into GVHD target organs plays a critical role in the development of GVHD and chemokines and their receptors are important molecules involved in this process. Here, we demonstrate in murine bone marrow transplantation models that the expression of the inflammatory CC chemokine receptor 2 (CCR2) on donor-derived CD8+ T cells is relevant for the control of CD8+ T-cell migration and development of GVHD. Recipients of CCR2-deficient (CCR2-/-) CD8+ T cells developed less damage of gut and liver than recipients of wild-type CD8+ T cells, which correlated with a reduction in overall GVHD morbidity and mortality. Assessment of donor CD8+ T-cell target organ infiltration revealed that CCR2-/- CD8+ T cells have an intrinsic migratory defect to the gut and liver. Other causes for the reduction in GVHD could be excluded, as alloreactive proliferation, activation, IFN-gamma production and cytotoxicity of CCR2-/- CD8+ T cells were intact. Interestingly, the graft-versus-tumor effect mediated by CCR2-/- CD8+ T cells was preserved, which suggests that interference with T-cell migration by blockade of CCR2 signaling can separate GVHD from GVT activity.