In vitro sensitivity to imatinib-induced inhibition of ABL kinase activity is predictive of molecular response in patients with de novo CML

Blood ◽  
2005 ◽  
Vol 106 (7) ◽  
pp. 2520-2526 ◽  
Author(s):  
Deborah White ◽  
Verity Saunders ◽  
A. Bruce Lyons ◽  
Susan Branford ◽  
Andrew Grigg ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
De Novo ◽  
Chronic Phase ◽  
Adaptor Protein ◽  
Prognostic Indicator ◽  
Molecular Response ◽  
Log Reduction ◽  
Abl Kinase ◽  
Marked Variability

AbstractMost patients with de novo chronic myeloid leukemia (CML) achieve good responses to imatinib, but the rate and degree of molecular response is variable. We assessed the inhibitory concentration 50% for imatinib (IC50imatinib) in 62 patients with de novo chronic-phase CML as a predictor of molecular response. IC50imatinib was determined in pretherapy blood samples by measuring the in vitro imatinib-induced reduction of the phosphorylated form of the adaptor protein Crkl (CT10 regulator of kinase like). There was marked variability between patients, with IC50imatinib ranging from 0.375 to 1.8 μM (median, 0.6 μM). Patients with low IC50imatinib (IC50 ≤ 0.6 μM; n = 36) had a 36% probability of achieving 2-log reduction in BCR-ABL (breakpoint cluster region-abelson) by 3 months compared with 8% in patients with high IC50imatinib (n = 26) (P = .01). The IC50imatinib was also predictive of molecular response at 12 months, with 47% of patients in the low IC50imatinib group achieving 3-log reduction and 23% in the high IC50imatinib group (P = .03). The predictive power of IC50imatinib was particularly strong in patients with low Sokal scores. These data provide strong evidence that intrinsic sensitivity to imatinib is variable in previously untreated patients with CML, and the actual level of BCR-ABL kinase inhibition achieved is critical to imatinib response. The IC50imatinib potentially provides a new prognostic indicator for molecular response in patients treated with imatinib. (Blood. 2005; 106:2520-2526)

scholarly journals Accumulation of DNA Damage and Alteration of the DNA Damage Response in Chronic Myeloid Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5364-5364
Author(s):  
Henning D. Popp ◽  
Vanessa Kohl ◽  
Johanna Flach ◽  
Susanne Brendel ◽  
Helga Kleiner ◽  
...  
Keyword(s):  
Dna Damage ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
De Novo ◽  
Chronic Phase ◽  
Molecular Response ◽  
Healthy Individuals ◽  
Blastic Transformation ◽  
Γh2ax Foci ◽  
Tki Treatment

The accumulation of DNA damage and the alteration of the DNA damage response (DDR) are critical features of genetic instability that is presumed to be implicated in BCR/ABL1-mediated blastic transformation of chronic myeloid leukemia (CML). The aim of our study was to analyze underlying mechanisms of genetic instability with regard to DNA damage such as DNA double-strand breaks (DSB), DSB repair and DDR signaling during blastic transformation of CML. Immunofluorescence microscopy of γH2AX was performed for quantification of DSB in peripheral blood mononuclear cells (PBMC) of 8 healthy individuals, 24 chronic phase (CP)-CML patients under current/discontinued tyrosine kinase inhibitor (TKI) treatment (21 patients in deep molecular response (DMR), 3 patients in major molecular response (MMR)), 5 CP-CML patients under current/discontinued TKI treatment with loss of MMR, 3 de novo non-treated CP-CML patients and 2 blast phase (BP)-CML patients. In addition, immunofluorescence microscopy of γH2AX/53BP1 was used for semi-quantification of error-prone DSB repair. Furthermore, immunoblotting of p-ATM, p-ATR, p-CHK1, p-CHK2 and p-TP53 was performed in PBMC of CML patients in comparison to PBMC of healthy individuals. Our analysis revealed an increase in numbers of γH2AX foci in PBMC of CP-CML patients under current/discontinued TKI treatment with loss of MMR (1.8 γH2AX foci per PBMC ± 0.4), in PBMC of de novo non-treated CP-CML patients (2.3 γH2AX foci per PBMC ± 0.7) and in PBMC of BP-CML patients (4.9 γH2AX foci per PBMC ± 0.9) as compared to the number of γH2AX foci in PBMC of healthy individuals (1.0 γH2AX foci per PBMC ± 0.1) and in PBMC of CP-CML patients under current/discontinued TKI treatment in DMR/MMR (1.0 γH2AX foci per PBMC ± 0.1) (Figure 1A and B). Analysis of co-localizing γH2AX/53BP1 foci in PBMC suggested progressive activation of error-prone nonhomologous end-joining repair mechanisms during blastic transformation in CML. Signatures of p-ATM, p-ATR, p-CHK1, p-CHK2 and p-TP53 indicated alterations of the DDR. In summary, our data provide evidence for an accumulation of DNA damage in PBMC of CML patients towards BP-CML patients. We hypothesize that ongoing DSB generation, error-prone DSB repair and DDR alterations might be critical mechanisms of blastic transformation in CML. Figure 1 Analysis of γH2AX foci in freshly isolated peripheral blood mononuclear cells (PBMC) of healthy individuals and chronic myeloid leukemia (CML) patients. (A) Exemplary immunofluorescence microscopic images of γH2AX foci (green, Alexa 488) and cell nuclei (blue, DAPI) in PBMC of a healthy individual (HEALTHY#3), a chronic phase CML patient with a deep molecular response to tyrosine kinase inhibitor (CP-CML DMR#16), a de novo non-treated chronic phase CML patient (CP-CML#1) and a blast phase CML patient (BP-CML#2). (B) γH2AX foci levels in PBMC of healthy individuals and in PBMC of CML patients. Figure 1 Disclosures Saussele: Pfizer: Honoraria; Novartis: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Fabarius:Novartis: Research Funding.

How I treat chronic myeloid leukemia in the imatinib era

Blood ◽  
2007 ◽  
Vol 110 (8) ◽  
pp. 2828-2837 ◽  
Author(s):  
John M. Goldman
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Initial Treatment ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Response To Treatment ◽  
Molecular Response ◽  
Newly Diagnosed ◽  
Allogeneic Transplant ◽  
Reduced Intensity Conditioning ◽  
Log Reduction

AbstractAlthough it is now generally accepted that imatinib is the best initial treatment for patients newly diagnosed with chronic myeloid leukemia (CML) in chronic phase, a number of questions remain unanswered. For example, (1) Is imatinib the best initial treatment for every chronic-phase patient? (2) At what dose should imatinib be started? (3) How should response to treatment be monitored? (4) For how long should the drug be continued in patients who have achieved and maintain a complete molecular response? (5) How does one handle a patient who achieves a 2-log but not a 3-log reduction in BCR-ABL transcripts? (6) How should response or failure be defined? (7) For the patient deemed to have failed imatinib, should one offer dasatinib or nilotinib? (8) For the patient who has failed imatinib but has a possible allogeneic transplant donor, should one offer dasatinib or nilotinib before recommending a transplantation? (9) Should the transplantation be myeloablative or reduced intensity conditioning? (10) How should one treat the patient who relapses after allografting? This paper will address these issues, many of which cannot yet be answered definitively.

Better Molecular Response (MR) to Imatinib (IM) in Early Chronic Phase (CP) Versus Late CP Chronic Myeloid Leukemia (CML) Patients (pts) in Complete Cytogenetic Response (CCR): A Comparison at 24 Months of 2 Clinical Trials of the GIMEMA Working Party on CML on Behalf of the GIMEMA Working Party on Chronic Myeloid Leukemia (GIMEMA-CML).

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1096-1096 ◽  
Author(s):  
Angela Poerio ◽  
Marilina Amabile ◽  
Ilaria Iacobucci ◽  
Simona Soverini ◽  
Sabrina Colarossi ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Nested Pcr ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Working Party ◽  
Cytogenetic Response ◽  
Interferon Α ◽  
Molecular Response ◽  
Front Line ◽  
Log Reduction

Abstract We sought to determine the differences in molecular response between early and late CP pts with CML who achieved a CCR after treatment with IM at the standard dose of 400mg/d. We studied 2 different cohorts of patients in CCR: 67/191 (35%) pts after α-Interferon (α-IFN) failure enrolled on the CML/002/STI571 protocol 53/76 (70%) pts treated front line with a combination of IM and pegilated IFN-α (PEG-IFN) enrolled on the CML/011/STI571 protocol Cytogenetic response was monitored on bone marrow (BM) metaphases and molecular response was assessed by real time RT-PCR (TaqMan) BM and peripheral blood (PB) samples, collected at baseline, 3, 6, 9 and 12 months during the first year, and every 6 months thereafter. Molecular response was expressed as the ratio between BCR/ABL and β2-microglobulin (β2-M) x100. The lowest level of detectability of the method was 10−5. Negative results (i.e. undetectable transcript) were confirmed by nested PCR performed 4 times (sensitivity 10−6). For the purpose of this analysis, a major molecular response (MMR) was defined as a BCR-ABL/β2M value <0.0001%, which turned out to be roughly equivalent to a 3-log reduction and a complete molecular response (CMR) was defined as negative (undetectable) BCR/ABL levels confirmed by nested PCR. We observed a progressive decrease of the amount of BCR/ABL transcript in pts who achieved a CCR. At 24 months the median reduction in BCR/ABL transcript level was: a 3-log reduction in late CP pts a 4-log reduction in early CP pts In the latter group of pts MR was assessed also at 36 months. So we observed that 36 months after the first dose of IM and PEG-IFN pts who were still in CCR had the median value of BCR/ABL transcript of 0.00001% both in BM and PB. Therefore all these pts achieved a MMR. However only 8/53 (4%) pts were in CMR (undetectable BCR/ABL at least once as assessed by nested PCR). We conclude that front-line treatment with IM results in a better quality MR (4-log reduction in BCR/ABL transcript levels in early CP pts, as against a 3-log reduction in late CP pts). Figure Figure

scholarly journals Impact of Baseline BCR-ABL Mutations on Response to Nilotinib in Patients With Chronic Myeloid Leukemia in Chronic Phase

2009 ◽  
Vol 27 (25) ◽  
pp. 4204-4210 ◽  
Author(s):  
Timothy Hughes ◽  
Giuseppe Saglio ◽  
Susan Branford ◽  
Simona Soverini ◽  
Dong-Wook Kim ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Phase Ii ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Cytogenetic Response ◽  
Molecular Response ◽  
Imatinib Resistance ◽  
Mutational Status ◽  
Imatinib Resistant

Purpose Nilotinib is a second-generation tyrosine kinase inhibitor indicated for the treatment of patients with chronic myeloid leukemia (CML) in chronic phase (CP; CML-CP) and accelerated phase (AP; CML-AP) who are resistant to or intolerant of prior imatinib therapy. In this subanalysis of a phase II study of nilotinib in patients with imatinib-resistant or imatinib-intolerant CML-CP, the occurrence and impact of baseline and newly detectable BCR-ABL mutations were assessed. Patients and Methods Baseline mutation data were assessed in 281 (88%) of 321 patients with CML-CP in the phase II nilotinib registration trial. Results Among imatinib-resistant patients, the frequency of mutations at baseline was 55%. After 12 months of therapy, major cytogenetic response (MCyR) was achieved in 60%, complete cytogenetic response (CCyR) in 40%, and major molecular response (MMR) in 29% of patients without baseline mutations versus 49% (P = .145), 32% (P = .285), and 22% (P = .366), respectively, of patients with mutations. Responses in patients who harbored mutations with high in vitro sensitivity to nilotinib (50% inhibitory concentration [IC50] ≤ 150 nM) or mutations with unknown nilotinib sensitivity were equivalent to those responses for patients without mutations (not significant). Patients with mutations that were less sensitive to nilotinib in vitro (IC50 > 150 nM; Y253H, E255V/K, F359V/C) had less favorable responses, as 13%, 43%, and 9% of patients with each of these mutations, respectively, achieved MCyR; none achieved CCyR. Conclusion For most patients with imatinib resistance and with mutations, nilotinib offers a substantial probability of response. However, mutational status at baseline may influence response. Less sensitive mutations that occurred at three residues defined in this study, as well as the T315I mutation, may be associated with less favorable responses to nilotinib.

scholarly journals Initial treatment for patients with CML

Hematology ◽  
2009 ◽  
Vol 2009 (1) ◽  
pp. 453-460 ◽  
Author(s):  
John M. Goldman
Keyword(s):  
Initial Treatment ◽  
Myeloid Leukemia ◽  
Kinase Inhibitor ◽  
Philadelphia Chromosome ◽  
Chronic Phase ◽  
Cytogenetic Response ◽  
Molecular Response ◽  
Major Molecular Response ◽  
Log Reduction ◽  
Advanced Phase

AbstractFor adult patients who present with chronic myeloid leukemia (CML) in chronic phase it is now generally agreed that initial treatment should start with the tyrosine kinase inhibitor (TKI) imatinib at 400 mg daily. Five years after starting imatinib about 60% of these patients will be in complete cytogenetic response (CCyR), still taking imatinib; an appreciable proportion of these will have achieved a major molecular response, defined as a 3-log reduction in the level of BCR-ABL1 transcripts in their blood. The patients in CCyR seem to have a very low risk of relapse to chronic phase or of progression to advanced phase. Other patients may be resistant to imatinib or may experience significant side effects that require change of therapy. The best method of monitoring responding patients is to enumerate Philadelphia chromosome–positive marrow metaphases at 3-month intervals until CCyR and to perform RQ-PCR for BCR-ABL1 transcripts at 3-month intervals after starting imatinib. The recommendations for defining “failure” and “sub-optimal response” proposed by the European LeukemiaNet in 2006 have proved to be a major contribution to assessing responses in individual patients and are now being updated. Patients who fail imatinib may respond to second-generation TKIs, but allogeneic stem cell transplantation still plays an important role for eligible patients who fare badly with TKIs. Patients who present in advanced phases of CML should be treated initially with TKI alone or with TKI in conjunction with cytotoxic drugs, but their overall prognosis is likely to be much inferior to that of those presenting in early chronic phase.

scholarly journals Mutational Profiles during the Progression of Chronic Myeloid Leukemia

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3596-3596
Author(s):  
Mengxing Xue ◽  
Zhao Zeng ◽  
Qinrong Wang ◽  
Lijun Wen ◽  
Yi Xu ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Conflicts Of Interest ◽  
Prognostic Significance ◽  
Chronic Phase ◽  
The Other ◽  
Molecular Response ◽  
Dismal Prognosis

Abstract Background: Despite significant improvements in the prognosis of chronic myeloid leukemia (CML) achieved by targeted therapy with tyrosine kinase inhibitors (TKIs), a small proportion of cases may not respond to TKIs or may relapse after an initial response, and then progress from chronic phase (CP) to blastic crisis (BC), characterized by a dismal prognosis. It remained uncertain whether the genetic lesions in addition to the BCR-ABL1 fusion could predict clinical outcomes of CML in the TKI era. Aim: To study the mutational profiles at each stage of CML and the prognostic significance of somatic mutations in addition to the BCR-ABL1 fusion in the TKI era. Patients and Methods: We performed targeted sequencing in 81 CML patients chosen retrospectively. 10 patients had optimal response to TKIs by European LeukemiaNet criteria and maintained durable major molecular response more than 5 years. 71 patients had progressed to accelerated phase (AP) or BC, of whom 43 had sequencing performed at paired CP and AP/BC samples, 28 at AP or BC samples. Totally, we analyzed 53 CP, 20 AP, and 61 BC samples. The targeted resequencing gene panel, covering 386 genes which were recurrently mutated in hematologic malignancies, were performed on a HiSeq 4000 NGS platform (Illumina). Results: Among the 53 CP samples, 20 (37.7%) had mutations involving 14 genes, and the number of mutated genes in each patient was 0-3 (median 0). ASXL1 was the most commonly mutated gene, 10/53 (18.9%) patients had this mutation, followed by KMT2D (4/53, 7.5%), PC (2/53, 3.8%), ERBB4 (2/53, 3.8%). ASXL1 mutation mainly existed in 43 patients with progressed disease , while only one case carried this mutation in 10 patients responsive to TKIs (20.9% vs 10%). 17/20 (85%) AP samples (including 10 patients progressed to AP and the other 10 patients who eventually progressed to BC from AP ) carried mutations involving 18 genes, the number of mutated genes in each patient was 0-6 (median 1.5). ABL1 was the most commonly mutated gene, and 8/20 (40%) patients had this mutation. The second was the ASXL1 mutation, 7 (7/20, 35%) patients carried this mutation. The other genes mutated in more than 2 patients included BCORL1 (3/20, 15%), RUNX1 (2/20, 10%), PHF6 (2/20, 10%), KMT2D (2/20, 10%), ATM (2/20, 10%). 54/61 (88.5%) BC samples (44 with myeloid crisis, 14 with lymphoid crisis, 3 with mixed phenotypic crisis) carried mutations, involving 41 genes, and the number of mutated genes in each patient was 0-9 (median 2). Similar to the mutation status in AP, the most commonly mutated gene was also ABL1, 24/61 (39.3%) patients carried this gene mutation, followed by ASXL1 mutation (13/61, 21.3%), and the other genes were in order, RUNX1 (11/61, 18.0%), WT1 (8/61, 13.1%), GATA2 (6/61, 9.8%), MED12 (5/61, 8.2%), IDH1 (5/61, 8.2%), TP53 (4/61 , 6.6%), KMT2D (4/61, 6.6%), etc. (Figure 1A) Among all the samples, 34 nonsynonymous variants in the ASXL1 gene were identified in 31 samples of 21 patients ( 3 samples with two variants). All the variants were frameshift and nonsense mutations, localized at the last exon of the ASXL1 gene. 13/21 patients with ASXL1 mutations had multi-stage samples. The median VAF of the ASXL1 mutations in the advanced stage was 31.4% (0-47.0%), which was significantly higher than that in CP at diagnosis (7.0%, 0-27.2%, P=0.033). Most of the ASXL1 mutations detected in CP expanded at the advanced disease, and were accompanied with other additional gene abnormalities, such as ABL1, RUNX1 and WT1 mutations, with the VAF similar to or lower than that of the ASXL1 mutations. In a few cases, the ASXL1 mutant clones in the CP disappeared, suggesting that some ASXL1 mutations may be clonal hematopoiesis unrelated to disease progression.(Figure 1B) In order to evaluate the effects of ASXL1 mutations on sensitivity to TKIs in vitro. We co-expressed P210-BCR-ABL1 fusion and ASXL1 mutation (G646Wfs*12) in Ba/F3 cells. Compared to Ba/F3 cells co-expressing BCR-ABL1 fusion and ASXL1 mutation (Ba/F3-BA/As), Ba/F3-BCR-ABL1 cells without ASXL1 mutation (Ba/F3-BA/Ve) showed higher sensitivity to TKIs, including imatinib, dasatinib and nilotinib.(Figure 1C) Conclusions: These results demonstrated the genetic lesions accumulated during the progression of CML from CP to BC. ASXL1 mutations were the most common genetic lesion in CP at diagnosis and may confer a poor prognosis, as it reduced the sensitivity to TKIs. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Clinical Entity and Outcomes of Therapy-Related Chronic Myeloid Leukemia in the Era of Tyrosine Kinase Inhibitors: Surveillance By the Chronic Myeloid Leukemia Cooperative Study Group

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3084-3084
Author(s):  
Noriyoshi Iriyama ◽  
Tomoiku Takaku ◽  
Eriko Sato ◽  
Maho Ishikawa ◽  
Tomonori Nakazato ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Treatment Response ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
De Novo ◽  
Chronic Phase ◽  
Study Group ◽  
Molecular Response ◽  
Cooperative Study ◽  
Cooperative Study Group

Abstract Background and Aim: Therapy-related chronic myeloid leukemia (TR-CML), which is defined as CML that developed after exposure to cytotoxic chemotherapy and/or radiotherapy, rarely exists in clinical practice, although its incidence rates are relatively lower than those of acute myeloid leukemia or myelodysplastic syndromes, accounting for 1.2-30.4% of secondary leukemias. The clinical behavior of TR-CML, including patient outcome, is reportedly not different from that of de novo CML before the era of imatinib treatment. While the recent advancement of CML treatment by the introduction of tyrosine kinase inhibitors (TKIs) has dramatically improved treatment outcomes in patients with CML, little is known about the treatment response and outcomes in patients with TR-CML treated with TKI. In this regard, we investigated the clinical entity of TR-CML in the era of TKIs, including treatment response to TKI and prognosis, in patients enrolled to the CML Cooperative Study Group. Patients and Methods: We retrospectively reviewed the data of patients enrolled in the CML Cooperative Study to identify patients diagnosed with TR-CML. This study included patients aged >15 years who were diagnosed with CML in the chronic phase between April 2001 and January 2016, and treated with any TKIs as initial therapy and followed up for at least 3 months. The study was approved by the research ethics board of each institution and conducted in accordance with the Declaration of Helsinki. A major molecular response (MMR) was defined as ≤0.1% on the International Scale (IS) or 100 copies of the BCR-ABL1 transcript/μg RNA in a transcription-mediated amplification and hybridization protection assay. A deep molecular response (DMR) was defined ≤0.0032% in the IS. Event-free survival (EFS) was defined as the period from the date of initial treatment with TKI to the date of onset of the first adverse event (loss of treatment efficacy, progression to the accelerated or blastic phase, or any cause of death) or the last follow-up. Statistical analyses were performed by using EZR. Results and Discussion: We identified 308 patients with newly diagnosed CML in the chronic phase, including 11 (3.6%) with TR-CML and 297 with de novo CML. Regarding the primary cancer, 2 of the 11 patients had breast cancer and the remaining 9 had prostate cancer, pharyngeal cancer, mesothelioma, lung cancer, colon cancer, ureter cancer, acute leukemia, gastric cancer, or bladder cancer, respectively. Eight cases were treated with chemotherapy, 2 were treated with radiotherapy, and the remaining case was treated with both chemotherapy and radiotherapy. The results of a cytogenetic analysis by G-banding were exclusive t(9;22)(q34;q11) in all the patients. The median time to diagnosis of CML from the initiation of chemotherapy and/or radiotherapy was 7 years (range, 1.2-33 years). No significant differences in patient age, sex, white blood cell count, hemoglobin level, platelet count, or European Treatment and Outcome Study risk were observed between the TR-CML and de novo CML groups. Among the patients whose cytogenetic and/or molecular responses were assessable, all had excellent treatment response to TKI. Seven patients unexpectedly reached MMR within 6 months after TKI initiation. Finally, 8 patients attained DMR or undetectable leukemia in the bone marrow and the remaining 3 attained MMR. The 5-year EFS of the patients in the de novo CML group was 90%. None of the patients in the TR-CML group experienced any adverse event. In conclusion, in the present study, we revealed that patients with TR-CML could attain a good clinical course with TKI therapy. Detailed investigations of TR-CML may provide new insights into the CML biology. Disclosures Iriyama: Novartis: Honoraria, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Speakers Bureau. Takaku:Bristol: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Nakazato:Mundipharma KK: Research Funding. Fujita:Chugai Pharmaceutical Co.,LTD: Honoraria. Tokuhira:Bristol Myers Squibb Co., Ltd: Honoraria; Pfizer Co., Ltd: Honoraria; Eizai Co., Ltd: Honoraria. Kawaguchi:Novartis: Honoraria.

Lymphoid Foci in Bone Marrow of Patients with Chronic Myeloid Leukaemia Treated with Imatinib.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2008-2008 ◽  
Author(s):  
Marion M. Roberts ◽  
David M. Ross ◽  
Timothy P. Hughes ◽  
Luen Bik To
Keyword(s):  
Bone Marrow ◽  
Chronic Phase ◽  
Cytogenetic Response ◽  
Response To Treatment ◽  
Molecular Response ◽  
Imatinib Treatment ◽  
Log Reduction ◽  
First Line Therapy ◽  
T Lymphocyte Proliferation

Imatinib treatment of CML is successful but long term. In spite of reported inhibition of T lymphocyte proliferation and activation, we noticed multiple lymphoid foci occurring in BM trephines from CML patients on Imatinib. Method: Patients with chronic phase CML were monitored with BM biopsies (generally 3 monthly) for 1 to 4 years on Imatinib (34 patients) and for 1.5 to 12 years on Interferon (22 patients). Three hundred and thirty-one trephine biopsies were assessed for the occurrence of lymphoid foci. Selected trephines with foci on recut sections were examined by immunocytochemistry with CD3 and CD20, and available aspirates were tested by flow cytometry and PCR for evidence of monoclonality. Results: Lymphoid foci in bone marrow trephines of patients with CML chronic phase occurred more frequently in Imatinib-treated patients (28/34 patients; 82%) than in Interferon-treated patients (9/22 patients; 41%) (p =0.001). Of 175 trephine biopsies from Imatinib-treated patients 68 (39%) contained lymphoid foci, compared to 18 of 156 (12%) trephines from Interferon-treated patients (p= 0.001). In 13/34 Imatinib-treated patients the BM trephine was positive on only one occasion, with 15/34 having multiple positive biopsies. In comparison BM trephine biopsies from random patients with various diagnoses have been described to have lymphoid foci in 3% of cases (Thiele et al, J Clin Pathology 1999,52,294). The majority of foci were interstitial but there were occasional paratrabecular foci. There was no difference between the incidence of foci in Imatinib-treated patients who had previously been treated with Interferon (11/14) and those who had Imatinib as first-line therapy (17/20). Lymphocyte numbers in BM aspirates were above normal in 32/175 aspirates and not coincident with the presence of foci in the corresponding trephines. Foci in the trephines examined by immunocytochemistry showed that the foci were a mixture of CD3 and CD20 positive cells. Flow cytometric immunophenotyping of available BM aspirates of patients with lymphoid foci showed no monoclonality, apart from 1 patient who developed monoclonal Non-Hodgkins lymphoma confined to the bone marrow during treatment with Imatinib. Only 2 patients had foci present at diagnosis of CML and one of these Imatinib-treated patients was the one who later developed NHL. Response to treatment as assessed by cytogenetic response could not be correlated with the development of lymphoid foci in the BM during treatment, as all Imatinib treated patients achieved complete cytogenetic remission. However patients with multiple positive trephine biopsies showed a trend (p=0.095) towards better molecular response as measured by a greater than 4 log reduction in BCR/ABL (8/14) than those with no lymphoid foci (1/6). Conclusion: Lymphoid foci occur frequently in the BM trephines of Imatinib- treated chronic phase CML patients; more commonly than in Interferon-treated CML patients. Both these patient groups have a higher number of lymphoid foci than is reported in random BM biopsies. This finding seems in contradiction to in vitro findings of Inatimib suppression of lymphocytic activation and proliferation. The occurrence of multiple foci suggests that the BM trephines and aspirates should continue to be monitored in Imatinib-treated patients. This early data also suggests that there may be a correlation of molecular response to Imatinib with the development of multiple lymphoid foci in the bone marrow.

Low Baseline Intrinsic Sensitivity to Imatinib (High IC50) in CML Patients Is Due to Reduced Oct-1 Mediated Influx. Intrinsic Sensitivity to AMN107 Does Not Correlate with That of Imatinib and Uptake of AMN107 Is Not Oct-1 Mediated.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1081-1081
Author(s):  
Deborah L. White ◽  
Verity A. Saunders ◽  
Jane Engler ◽  
Phuong Dang ◽  
Andrew C.W. Zannettino ◽  
...  
Keyword(s):  
Drug Concentration ◽  
De Novo ◽  
Adaptor Protein ◽  
Organic Cation Transporter ◽  
Intracellular Concentration ◽  
Lower Probability ◽  
P Value ◽  
Molecular Response ◽  
Ic50 Values

Abstract We have recently demonstrated that there is variation in the intrinsic sensitivity of de novo CML patients to imatinib. Patients with low intrinsic sensitivity to imatinib, have a lower probability of achieving major molecular response by 12 months. Intrinsic sensitivity was determined pre-therapy using western blot, with the IC50imatinib defined as the dose of drug required in vitro to reduce phosphorylation of the adaptor protein Crkl (p-Crkl) by 50%. In the current study we show that the observed variation in IC50imatinib between patients can be explained by the intracellular concentration of imatinib. In 16 de novo CML patients the IC50imatinib strongly correlated (R2 = −0.6, p = 0.002) with the intracellular concentration of 14C-labelled imatinib after 2 hours exposure at 37°C. In keeping with the notion that the organic cation transporter Oct-1 is responsible for imatinib influx, the addition of Prazosin, an inhibitor of Oct-1, to 14C imatinib experiments greatly reduced the inter-patient variation in intracellular concentration. Intracellular drug concentration. Median IC50imatinib uM [imatinib] in-vitro * [imatinib] in-vitro* + Prazosin Median IC50AMN107 uM [AMN107] in-vitro * [AMN107] in-vitro* + Prazosin * ng of intracellular imatinib or AMN107 per 200000 cells when 2uM drug added in vitro. low IC50 imatinib (n=8) 0.5 28.4 6.9 0.035 28.6 27.4 p<0.001 p>0.05 high IC50 imatinib (n=8) 1.375 14.8 8.4 0.04 28.5 27.6 p value <0.001 0.04 >0.05 >0.05 >0.05 >0.05 p=0.03 p>0.05 We have now demonstrated that IC50 values for the novel, more selective Bcr-Abl inhibitor AMN107 are on average 22-fold lower than those observed for imatinib and there is no correlation between the IC50 values for imatinib and AMN107 (R2 = 0.375, p>0.05). There was also less inter-patient variation in AMN107 IC50 (range 0.07uM) when compared to imatinib (range 3.1uM). In contrast to imatinib, there is no correlation between IC50AMN107 and the intracellular concentration of drug achieved in 14C-uptake studies (R2 = 0.337, p>0.05). Further to this the addition of prazosin had no effect on influx of AMN107 suggesting that Oct-1 may not be a rate limiting determinant of intracellular drug concentration. In conclusion, variable Oct-1 mediated influx of imatinib may explain the heterogeneous IC50imatinib values we have observed in de novo CML patients. Oct-1 mediated influx may therefore be a key determinant of molecular response to imatinib. The causes of inter-patient variability in Oct-1 mediated influx requires further investigation. By contrast, poor Oct-1 mediated uptake is unlikely to have any impact on response to AMN107. This may be of relevance to patients with low intrinsic sensitivity to imatinib.

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