Nilotinib restores long-term full-donor chimerism in Ph-positive acute lymphoblastic leukemia relapsed after allogeneic transplantation

Nilotinib Treatment of Patients Affected by Chronic Graft-versus-Host Disease Reduces Collagen Production and Skin Fibrosis by Downmodulating the TGF-β and p-SMAD Pathway

The present study was conducted to investigate cellular and molecular features of chronic graft-versus-host disease fibroblasts (GVHD-Fbs) and to assess the effectiveness of nilotinib as a fibrosis modulator. Growth kinetics, phenotype, and differentiation of cultured skin biopsy-derived GVHD-Fbs were compared with normal fibroblasts from both a dermal cell line (n-Fbs) and healthy individuals undergoing cosmetic surgery (n-skin-Fbs). Collagen genes (COL1α1/COL1α2) and p-SMAD2 expression were assessed by real-time PCR and immunofluorescence. The in vivo effects of nilotinib on chronic GVHD (cGVHD)-affected skin were investigated by immunohistochemistry; the relationship to TGF-β plasma levels was assessed. Although the morphology, phenotype, and differentiation of cultured GVHD-Fbs were comparable to normal fibroblasts, growth was slower and senescence was reached earlier. The expression of COL1α1 and COL1α2 mRNAs was respectively 4 and 1.6 times higher in cGVHD-Fbs (P = .02); the addition of TGF-β increased n-Fbs, but not GVHD-Fbs, collagen gene expression. Compared with the baseline, the addition of 1 μM nilotinib induced 86.5% and 49% reduction in COL1α1 and COL1α2 expression in cultured GVHD-Fbs, respectively (P< .01). In vivo immunohistochemistry analysis of skin biopsy specimens from patients with cGVHD showed strong baseline staining for COL1α1 and COL1α2, which decreased sharply after 180 days of nilotinib; immunofluorescence revealed TGF-β inhibition and p-Smad2 reduction at the intracellular level. Of note, nilotinib treatment was associated with normalization of TGF-β levels both in culture supernatants and in plasma. In general, the data show that cGVHD fibroblasts promote fibrosis through abnormal collagen production induced by hyperactive TGF-β signaling. TGF-β inhibition at the intracellular and systemic level represents an essential antifibrotic mechanism of nilotinib in a clinical setting.

Immunomodulatory Effects of Tyrosine Kinase Inhibitor In Vitro and In Vivo Study

Pathogenesis of chronic graft-versus-host disease (cGVHD) is incompletely defined, involving donor-derived CD4 and CD8-positive T lymphocytes as well as B cells. Standard treatment is lacking for steroid-dependent/refractory cases; therefore, the potential usefulness of tyrosine kinase inhibitors (TKIs) has been suggested, based on their potent antifibrotic effect. However, TKIs seem to have pleiotropic activity. We sought to evaluate the in vitro and in vivo impact of different TKIs on lymphocyte phenotype and function. Peripheral blood mononuclear cells (PBMCs) from healthy donors were cultured in the presence of increasing concentrations of nilotinib, imatinib, dasatinib, and ponatinib; in parallel, 44 PBMC samples from 15 patients with steroid-dependent/refractory cGVHD treated with nilotinib in the setting of a phase I/II trial were analyzed at baseline, after 90, and after 180 days of therapy. Flow cytometry was performed after labeling lymphocytes with a panel of monoclonal antibodies (CD3, CD4, CD16, CD56, CD25, CD19, CD45RA, FoxP3, CD127, and 7-amino actinomycin D). Cytokine production was assessed in supernatants of purified CD3⁺ T cells and in plasma samples from nilotinib-treated patients. Main T lymphocyte subpopulations were not significantly affected by therapeutic concentrations of TKIs in vitro, whereas proinflammatory cytokine (in particular, IL-2, IFN-γ, tumor necrosis factor-α, and IL-10) and IL-17 production showed a sharp decline. Frequency of T regulatory, B, and natural killer (NK) cells decreased progressively in presence of therapeutic concentrations of all TKIs tested in vitro, except for nilotinib, which showed little effect on these subsets. Of note, naive T regulatory cell (Treg) subset accumulated after exposure to TKIs. Results obtained in vivo on nilotinib-treated patients were largely comparable, both on lymphocyte subset kinetics and on cytokine production by CD3-positive cells. This study underlines the anti-inflammatory and immunomodulatory effects of TKIs and supports their potential usefulness as treatment for patients with steroid-dependent/refractory cGVHD. In addition, both in vitro and in vivo data point out that compared with other TKIs, nilotinib could better preserve the integrity of some important regulatory subsets, such as Treg and NK cells.

Patients with Philadelphia-positive leukemia with BCR-ABL kinase mutations before allogeneic transplantation predominantly relapse with the same mutation

Despite the successes of tyrosine kinase inhibitors (TKIs) in improving outcomes in patients with chronic myeloid leukemia (CML) and Philadelphia-positive acute lymphoblastic leukemia (Ph + ALL), allogeneic hematopoietic stem cell transplantation (HSCT) continues to be an important and potentially curative option for selected patients with either disease. After HSCT, TKIs are increasingly being used to treat or prevent disease relapse, and practice patterns suggest that these TKIs are often chosen empirically without regard to pre-HSCT mutation status. We investigated whether ABL kinase domain mutations persist after transplantation and, thus, whether pre-HSCT mutation status should inform the selection of post-HSCT TKIs in these patients. We retrospectively analyzed adults who underwent allogeneic HSCT for CML and Ph + ALL at our institution between 2000 and 2010, and we identified subjects who had detectable BCR-ABL transcripts by polymerase chain reaction (PCR), as well as available RNA for Sanger sequencing of the ABL kinase domain, in both the pre- and post-HSCT settings. In total, 95 CML and 20 Ph + ALL patients with positive PCR transcripts were identified, of which 10 (10.5%) and 4 (20.0%), respectively, were found to have pre-HSCT ABL kinase mutations known to confer TKI resistance. In 9 (64.2%) of these 14 patients, the same kinase mutation was also detectable at an average time of 191 days after HSCT. Seven (50.0%) of the 14 harboring mutations had relapsed/refractory disease by last follow-up, of which, in retrospect, 6 had received a predictably ineffective TKI within the first 100 days after transplantation based on our mutation analysis. These data support the idea that pre-existing mutations in the ABL kinase domain, frequently associated with resistance to TKIs and prevalent in a transplantation population, are persistently detectable in the majority of patients after transplantation. We propose that such resistance patterns should be considered when selecting TKIs in the post-HSCT setting, including clinical trials of post-HSCT TKI prophylaxis.

Efficacy and pharmacologic data of second-generation tyrosine kinase inhibitor nilotinib in BCR-ABL-positive leukemia patients with central nervous system relapse after allogeneic stem cell transplantation

Central nervous system (CNS) involvement is a severe complication of BCR-ABL-positive leukemia after allogenic stem cell transplantation (alloSCT) associated with fatal outcome. Although second-generation tyrosine-kinase inhibitors (TKI) such as nilotinib have shown activity in systemic BCR-ABL⁺ disease, little data exists on their penetration and efficacy within the CNS. Four patients (3 male, 1 female; age 15–49) with meningeal relapse after alloSCT and subsequent treatment with nilotinib were identified. A total of 17 cerebrospinal fluid (csf) and serum samples were assessed for nilotinib concentration and patient outcome was recorded. Nilotinib concentrations showed a low median csf/plasma ratio of 0.53% (range 0.23–1.5%), yet pronounced clinical efficacy was observed with long-lasting responses (>1 year) in three patients. Comparison with historical data showed a trend towards superior efficacy of nilotinib versus imatinib. Despite poor csf penetration, nilotinib showed significant clinical activity in CNS relapse of BCR-ABL⁺ leukemias. As nilotinib has a high protein-binding affinity, the low-protein concentration in csf could translate into a relatively higher amount of free and therefore active nilotinib in csf as compared to blood, possibly explaining the observed efficacy. Thus, treatment with a 2nd generation TKI warrants further investigation and should be considered in cases of CNS relapse of BCR-ABL-positive leukemia after alloSCT.

Persistent complete molecular remission after nilotinib and graft-versus-leukemia effect in an acute lymphoblastic leukemia patient with cytogenetic relapse after allogeneic stem cell transplantation

We report the successful treatment and sustained molecular remission using single agent nilotinib in a relapsed Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia patient after allogeneic hematopoietic stem cell transplantation. Compared to previously published studies, this is the first report where a patient did not receive additional chemotherapy after relapse, nor did she receive donor lymphocyte infusions. With nilotinib, the patient reverted back to normal blood counts and 100% donor reconstitution by single tandem repeat (STR) chimerism analysis in the bone marrow and in peripheral blood, granulocytes, T and B-lymphocytes. This report also highlights the use of nilotinib in combination with extracorporeal photopheresis (ECP) for concomitant graft-versus-host disease. Our data suggests that ECP, together with nilotinib, did not adversely affect the overall Graft-versus-leukemia (GVL) effect.

Tirosin kinase inhibitors in chronic graft versus host disease: from bench to bedside

Chronic Graft Versus Host Disease (cGVHD) is a major complication of allogeneic stem-cell transplantation (SCT). In many inflammatory fibrotic diseases, such as Systemic Scleroderma (SSc) and cGVHD with fibrotic features, an abnormal activation of transforming growth factor (TGFβ) and platelet-derived growth factor receptor (PDGF-R) pathways have been observed. Tyrosin Kinase Inhibitors (TKIs), which are currently used for treatment of patients with Chronic Myeloid Leukemia (CML), share potent antifibrotic and antiinflammatory properties, being powerful dual inhibitors of both PDGF-R and TGFβ pathways. Moreover accumulating in vitro data confirm that TKIs, interacting with the TCR and other signalling molecules, carry potent immunomodulatory effects, being involved in both T-cell and B-cell response. Translation to the clinical setting revealed that treatment with Imatinib can achieve encouraging responses in patients with autoimmune diseases and steroid-refractory cGVHD, showing a favourable toxicity profile. While the exact mechanisms leading to such efficacy are still under investigation, use of TKIs in the context of clinical trials should be promoted, aiming to evaluate the biological changes induced in vivo by TKIs and to assess the long term outcome of these patients. Second-generation TKIs, with more favourable toxicity profile are under evaluation in the same setting.