Treatment-free remission after a second TKI discontinuation attempt in patients with Chronic Myeloid Leukemia re-treated with dasatinib - interim results from the DAstop2 trial

Tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) has become part of routine care for patients with a sustained deep molecular response (DMR). Approximately 50% experience a molecular relapse upon TKI cessation. Most of them quickly regain DMR upon TKI resumption. Whether these patients can achieve a second treatment-free remission (TFR) remains unclear. DAstop2 (ClinicalTrials.gov ID: NCT03573596) is a prospective study including patients with a failed first TFR attempt re-treated with any TKI for ≥ one year. Upon entering the study, patients received the TKI dasatinib for additional two years. Patients with sustained DMR for ≥1 year qualified for a second TKI stop. Ninety-four patients were included between Oct 2017-Dec 2021. At the time of data analysis, 62 patients had attempted a 2nd stop. After a median follow-up of 27 months from 2nd stop, TFR rates were 61, 56 and 46% at 6, 12 and 24 months respectively. No progression to advanced stage disease was seen and 87% had re-achieved MR4 within a median of 3 months from TKI re-initiation. In summary, we show that a 2nd TFR attempt after dasatinib treatment is safe, feasible and TFR rates seem in the range of those reported in trials of a first TKI stop.

European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in Chronic Myeloid Leukemia: Final Analysis and Novel Prognostic Factors for Treatment-Free Remission

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The European Stop Kinase Inhibitors (EURO-SKI) study is the largest clinical trial for investigating the cessation of tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia in stable deep molecular remission (DMR). Among 728 patients, 434 patients (61%; 95% CI, 57 to 64) remained in major molecular response (MMR) at 6 months and 309 patients of 678 (46%; 95% CI, 42 to 49) at 36 months. Duration of TKI treatment and DMR before TKI stop were confirmed as significant factors for the prediction of MMR loss at 6 months. In addition, the type of BCR::ABL1 transcript was identified as a prognostic factor. For late MMR losses after 6 months, TKI treatment duration, percentage of blasts in peripheral blood, and platelet count at diagnosis were significant factors in multivariate analysis. For the entire study period of 36 months, multiple logistic regression models confirmed duration of treatment, blasts, and transcript type as independent factors for MMR maintenance. In addition to the duration of treatment, transcript type as well as blasts in peripheral blood at diagnosis should be considered as important factors to predict treatment-free remission.

Single-cell analysis of immune recognition in chronic myeloid leukemia patients following tyrosine kinase inhibitor discontinuation

Immunological control of residual leukemia cells is thought to occur in patients with chronic myeloid leukemia (CML) that maintain treatment-free remission (TFR) following tyrosine kinase inhibitor (TKI) discontinuation. To study this, we analyzed 55 single-cell RNA and T cell receptor (TCR) sequenced samples (scRNA+TCRαβ-seq) from patients with CML (n = 13, N = 25), other cancers (n = 28), and healthy (n = 7). The high number and active phenotype of natural killer (NK) cells in CML separated them from healthy and other cancers. Most NK cells in CML belonged to the active CD56dim cluster with high expression of GZMA/B, PRF1, CCL3/4, and IFNG, with interactions with leukemic cells via inhibitory LGALS9-TIM3 and PVR-TIGIT interactions. Accordingly, upregulation of LGALS9 was observed in CML target cells and TIM3 in NK cells when co-cultured together. Additionally, we created a classifier to identify TCRs targeting leukemia-associated antigen PR1 and quantified anti-PR1 T cells in 90 CML and 786 healthy TCRβ-sequenced samples. Anti-PR1 T cells were more prevalent in CML, enriched in bone marrow samples, and enriched in the mature, cytotoxic CD8 + TEMRA cluster, especially in a patient maintaining TFR. Our results highlight the role of NK cells and anti-PR1 T cells in anti-leukemic immune responses in CML.

Autologous hematopoietic stem cell transplantation significantly alters circulating ceramides in peripheral blood of relapsing-remitting multiple sclerosis patients

BACKGROUND

The common inflammatory disease multiple sclerosis (MS) is a disease of the central nervous system. For more than 25 years autologous hematopoietic stem cell transplantation (AHSCT) has been used to treat MS. It has been shown to be highly effective in suppressing inflammatory activity in relapsing-remitting MS (RRMS) patients. This treatment is thought to lead to an immune system reset, inducing a new, more tolerant system; however, the precise mechanism behind the treatment effect in MS patients is unknown. In this study, the effect of AHSCT on the metabolome and lipidome in peripheral blood from RRMS patients was investigated.

METHODS

Peripheral blood samples were collected from 16 patients with RRMS at ten-time points over the five months course of AHSCT and 16 MS patients not treated with AHSCT. Metabolomics and lipidomics analysis were performed using liquid-chromatography high-resolution mass spectrometry. Mixed linear models, differential expression analysis, and cluster analysis were used to identify differentially expressed features and groups of features that could be of interest. Finally, in-house and in-silico libraries were used for feature identification, and enrichment analysis was performed.

RESULTS

Differential expression analysis found 657 features in the lipidomics dataset and 34 in the metabolomics dataset to be differentially expressed throughout AHSCT. The administration of cyclophosphamide during mobilization and conditioning was associated with decreased concentrations in glycerophosphoinositol species. Thymoglobuline administration was associated with an increase in ceramide and glycerophosphoethanolamine species. After the conditioning regimen, a decrease in glycerosphingoidlipids concentration was observed, and following hematopoietic stem cell reinfusion glycerophosphocholine concentrations decreased for a short period of time. Ceramide concentrations were strongly associated with leukocyte levels during the procedure. The ceramides Cer(d19:1/14:0) and Cer(d20:1/12:0) were found to be increased (P < .05) in concentration at the three-month follow-up compared to baseline. C16 ceramide, Cer(D18:2/16:0), and CerPE(d16:2(4E,6E)/22:0) were found to be significantly increased in concentration after AHSCT compared to prior to treatment as well as compared to newly diagnosed RRMS patients.

CONCLUSION

AHSCT had a larger impact on the lipids in peripheral blood compared to metabolites. The variation in lipid concentration reflects the transient changes in the peripheral blood milieu during the treatment, rather than the changes in the immune system that are assumed to be the cause of clinical improvement within RRMS patients treated with AHSCT. Ceramide concentrations were affected by AHSCT and associated with leukocyte counts and were altered three months after treatment, suggesting a long-lasting effect.

Characterization of the bone marrow niche in patients with chronic myeloid leukemia identifies CXCL14 as a new therapeutic option

Although tyrosine kinase inhibitors (TKIs) are effective in treating chronic myeloid leukemia (CML), they often fail to eradicate the leukemia-initiating stem cells (LSCs), causing disease persistence and relapse. Evidence indicates that LSC persistence may be because of bone marrow (BM) niche protection; however, little is known about the underlying mechanisms. Herein, we molecularly and functionally characterize BM niches in patients with CML at diagnosis and reveal the altered niche composition and function in these patients. Long-term culture initiating cell assay showed that the mesenchymal stem cells from patients with CML displayed an enhanced supporting capacity for normal and CML BM CD34+CD38- cells. Molecularly, RNA sequencing detected dysregulated cytokine and growth factor expression in the BM cellular niches of patients with CML. Among them, CXCL14 was lost in the BM cellular niches in contrast to its expression in healthy BM. Restoring CXCL14 significantly inhibited CML LSC maintenance and enhanced their response to imatinib in vitro, and CML engraftment in vivo in NSG-SGM3 mice. Importantly, CXCL14 treatment dramatically inhibited CML engraftment in patient-derived xenografted NSG-SGM3 mice, even to a greater degree than imatinib, and this inhibition persisted in patients with suboptimal TKI response. Mechanistically, CXCL14 upregulated inflammatory cytokine signaling but downregulated mTOR signaling and oxidative phosphorylation in CML LSCs. Together, we have discovered a suppressive role of CXCL14 in CML LSC growth. CXCL14 might offer a treatment option targeting CML LSCs.

IFN-α with dasatinib broadens the immune repertoire in patients with chronic-phase chronic myeloid leukemia

In chronic myeloid leukemia (CML), combination therapies with tyrosine kinase inhibitors (TKIs) aim to improve the achievement of deep molecular remission that would allow therapy discontinuation. IFN-α is one promising candidate, as it has long-lasting effects on both malignant and immune cells. In connection with a multicenter clinical trial combining dasatinib with IFN-α in 40 patients with chronic-phase CML (NordCML007, NCT01725204), we performed immune monitoring with single-cell RNA and T cell receptor (TCR) sequencing (n = 4, 12 samples), bulk TCRβ sequencing (n = 13, 26 samples), flow cytometry (n = 40, 106 samples), cytokine analyses (n = 17, 80 samples), and ex vivo functional studies (n = 39, 80 samples). Dasatinib drove the immune repertoire toward terminally differentiated NK and CD8⁺ T cells with dampened functional capabilities. Patients with dasatinib-associated pleural effusions had increased numbers of CD8⁺ recently activated effector memory T (Temra) cells. In vitro, dasatinib prevented CD3-induced cell death by blocking TCR signaling. The addition of IFN-α reversed the terminally differentiated phenotypes and increased the number of costimulatory intercellular interactions and the number of unique putative epitope-specific TCR clusters. In vitro IFN-α had costimulatory effects on TCR signaling. Our work supports the combination of IFN-α with TKI therapy, as IFN-α broadens the immune repertoire and restores immunological function.

Migrating to Long-Read Sequencing for Clinical Routine BCR-ABL1 TKI Resistance Mutation Screening

Objective

The aim of this project was to implement long-read sequencing for BCR-ABL1 TKI resistance mutation screening in a clinical setting for patients undergoing treatment for chronic myeloid leukemia.

Materials and Methods

Processes were established for registering and transferring samples from the clinic to an academic sequencing facility for long-read sequencing. An automated analysis pipeline for detecting mutations was established, and an information system was implemented comprising features for data management, analysis and visualization. Clinical validation was performed by identifying BCR-ABL1 TKI resistance mutations by Sanger and long-read sequencing in parallel. The developed software is available as open source via GitHub at https://github.com/pharmbio/clamp.

Results

The information system enabled traceable transfer of samples from the clinic to the sequencing facility, robust and automated analysis of the long-read sequence data, and communication of results from sequence analysis in a reporting format that could be easily interpreted and acted upon by clinical experts. In a validation study, all 17 resistance mutations found by Sanger sequencing were also detected by long-read sequencing. An additional 16 mutations were found only by long-read sequencing, all of them with frequencies below the limit of detection for Sanger sequencing. The clonal distributions of co-existing mutations were automatically resolved through the long-read data analysis. After the implementation and validation, the clinical laboratory switched their routine protocol from using Sanger to long-read sequencing for this application.

Conclusions

Long-read sequencing delivers results with higher sensitivity compared to Sanger sequencing and enables earlier detection of emerging TKI resistance mutations. The developed processes, analysis workflow, and software components lower barriers for adoption and could be extended to other applications.

Abstract PO-018: Inflaming advanced solid tumors including pancreatic cancer using LOAd703, a TMZ-CD40L/4-1BBL-armed oncolytic virus

Pancreatic ductal adenocarcinoma (PDAC) is resistant to PD1/PDL1 blocking antibodies. The purpose of this study was to evaluate if immunotherapy with LOAd703, an oncolytic adenovirus armed with trimerized CD40L and 4-1BBL, can sensitize PDAC to mAbs targeting PD1/PDL1. The high content of myeloid-derived suppressor cells (MDCSs) in the tumor microenvironment may in part explain the limited anti-tumor T cell response in PDAC. We have previously shown that gemcitabine can reduce MDSCs in patients with PDAC, with the T cell proliferative capacity remaining intact. Further, LOAd703 has been demonstrated to efficiently and robustly kill PDAC cells and stimulate the maturation of dendritic cells (DCs), which, in turn, induces T cell activation. Patients with advanced PDAC, colorectal, biliary, and ovarian cancer (NCT03225989) were treated with intratumoral injections of LOAd703 combined with appropriate chemotherapy such as gemcitabine ± nab-paclitaxel for PDAC patients, or combined with gemcitabine if there was no standard of care. Blood sampling was performed for immune cell profiling and anti-adenovirus antibodies (flow cytometry, ELISA). Tumor biopsies were also analyzed for mRNA expression (NanoString; PanCancer Immune Profiling Panel). The study was approved by the ethical review board and the Swedish Medical Products Agency. The dose of LOAd703 was escalated (5 × 10e10 VP, 1 × 10e11 VP, 5 × 10e11VP) in separate cohorts of new patients and administered every other week. To date, blood samples from 23 patients have been analyzed by flow cytometry to profile immune cells. The mean percentages of monocytic- and granulocytic MDSCs, Tregs and M2-like myeloid cells were significantly decreased after treatment initiation. The effector memory (EM) and central memory (CM) CD8+ T cells were significantly increased, while naïve and CM cells were increased among CD4 T cells. Both CD4 and CD8 T cells expressing ICOS were present post-treatment but only CD8 T cells showed significant elevation of PD1. The NanoString data were analyzed using published mRNA immune signatures (bioinformatics). LOAd703 in combination with chemotherapy inflamed tumor lesions as shown by increased markers of the T cell inflamed signature (16 genes), T effector cell signature (19 genes), expanded immune signature (25 genes) and IFNg-related gene signature (12 genes) (week 1 versus week 13). Anti-adenovirus antibody titers increased in all patients after treatment initiation. The antibody levels did not correlate with the dose of virus, radiological response to treatment, nor overall survival. The results presented herein show that LOAd703 combined with chemotherapy enhances immune reactivity in patients with immune cold tumors as demonstrated by increases in EM and CM T cells in the peripheral blood, while suppressive immune cells were decreased. Further, the tumor milieu was inflamed post treatment as shown by mRNA profiling. Hence, LOAd703 may sensitize immune cold tumors to mAbs targeting PD1/PDL1.

Citation Format: Jessica Wenthe, Emma Eriksson, Linda Sandin, Tanja Lövgren, Justyna Leja Jarblad, Hanna Dahlstrand, Ulla Olsson-Strömberg, Aglaia Schiza, Anders Sundin, Sandra Irenaeus, Eric Rowinsky, Gustav Ullenhag, Angelica Loskog. Inflaming advanced solid tumors including pancreatic cancer using LOAd703, a TMZ-CD40L/4-1BBL-armed oncolytic virus [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-018.

Long-term tolerability and efficacy after initial PegIFN-α addition to dasatinib in CML-CP: Five-year follow-up of the NordCML007 study

OBJECTIVES

Treatment-free remission (TFR) has emerged as a treatment goal in chronic myeloid leukemia in the chronic phase (CML-CP). Attempts to increase proportion of patients achieving TFR include combination of tyrosine kinase inhibitors (TKI) and other drugs. Interferon-α in addition to TKI has shown promising efficacy but with dose-dependent toxicity and discontinuations. NordCML007 was initiated to study the efficacy and safety of low dose pegylated IFN-α (PegIFN-α) in combination with dasatinib (DAS) in CML-CP.

METHODS

Forty patients with newly diagnosed CML-CP were given DAS upfront. After month 3 (M3) 15 μg/wk of PegIFN-α was added and increased to 25 μg/wk from M7 until M15. DAS treatment was continued and adverse events and BCR-ABL1 qRT-PCR values were reported yearly after M24. Results from M1 to M18 have previously been published, and here we present long-term data.

RESULTS

After 5 years of follow-up, there were no suspected unexpected serious adverse reactions, no increase in serosal effusions, no disease progressions and no CML-related deaths. Rates of MR^3.0 (MMR), MR^4.0 and MR^4.5 were 84.6%, 64.1% and 51.3% respectively at M60, and 95% of patients reached MMR at some point during the study.

CONCLUSION

Initial addition of PegIFN-α to DAS shows good long-term efficacy without increased toxicity.

Successful tyrosine kinase inhibitor discontinuation outside clinical trials - data from the population-based Swedish chronic myeloid leukaemia registry

Clinical trials show that tyrosine kinase inhibitor (TKI) treatment can be discontinued in selected patients with chronic myeloid leukaemia (CML). Although updated CML guidelines support such procedure in clinical routine, data on TKI stopping outside clinical trials are limited. In this retrospective study utilising the Swedish CML registry, we examined TKI discontinuation in a population-based setting. Out of 584 patients diagnosed with chronic-phase CML (CML-CP) in 2007-2012, 548 had evaluable information on TKI discontinuation. With a median follow-up of nine years from diagnosis, 128 (23%) discontinued TKI therapy (≥1 month) due to achieving a DMR (deep molecular response) and 107 (20%) due to other causes (adverse events, allogeneic stem cell transplant, pregnancy, etc). Among those stopping in DMR, 49% re-initiated TKI treatment (median time to restart 4·8 months). In all, 38 patients stopped TKI within a clinical study and 90 outside a study. After 24 months 41·1% of patients discontinuing outside a study had re-initiated TKI treatment. TKI treatment duration pre-stop was longer and proportion treated with second-generation TKI slightly higher outside studies, conceivably affecting the clinical outcome. In summary we show that TKI discontinuation in CML in clinical practice is common and feasible and may be just as successful as when performed within a clinical trial.

Bosutinib for pretreated patients with chronic phase chronic myeloid leukemia: primary results of the phase 4 BYOND study

Bosutinib is approved for newly diagnosed Philadelphia chromosome-positive (Ph+) chronic phase (CP) chronic myeloid leukemia (CML) and for Ph+ CP, accelerated (AP), or blast (BP) phase CML after prior treatment with tyrosine kinase inhibitors (TKIs). In the ongoing phase 4 BYOND study (NCT02228382), 163 CML patients resistant/intolerant to prior TKIs (n = 156 Ph+ CP CML, n = 4 Ph+ AP CML, n = 3 Ph-negative/BCR-ABL1+ CML) received bosutinib 500 mg once daily (starting dose). As of ≥1 year after last enrolled patient (median treatment duration 23.7 months), 56.4% of Ph+ CP CML patients remained on bosutinib. Primary endpoint of cumulative confirmed major cytogenetic response (MCyR) rate by 1 year was 75.8% in Ph+ CP CML patients after one or two prior TKIs and 62.2% after three prior TKIs. Cumulative complete cytogenetic response (CCyR) and major molecular response (MMR) rates by 1 year were 80.6% and 70.5%, respectively, in Ph+ CP CML patients overall. No patient progressed to AP/BP on treatment. Across all patients, the most common treatment-emergent adverse events were diarrhea (87.7%), nausea (39.9%), and vomiting (32.5%). The majority of patients had confirmed MCyR by 1 year and MMR by 1 year, further supporting bosutinib use for Ph+ CP CML patients resistant/intolerant to prior TKIs.

The EUTOS long-term survival (ELTS) score is superior to the Sokal score for predicting survival in chronic myeloid leukemia

Prognostic scores support clinicians in selecting risk-adjusted treatments and in comparatively assessing different results. For patients with chronic-phase chronic myeloid leukemia (CML), four baseline prognostic scores are commonly used. Our aim was to compare the prognostic performance of the scores and to arrive at an evidence-based score recommendation. In 2949 patients not involved in any score development, higher hazard ratios and concordance indices in any comparison demonstrated the best discrimination of long-term survival with the ELTS score. In a second step, of 5154 patients analyzed to investigate risk group classification differences, 23% (n = 1197) were allocated to high-risk by the Sokal score. Of the 1197 Sokal high-risk patients, 56% were non-high-risk according to the ELTS score and had a significantly more favorable long-term survival prognosis than the 526 high-risk patients according to both scores. The Sokal score identified too many patients as high-risk and relatively few (40%) as low-risk (versus 60% with the ELTS score). Inappropriate risk classification jeopardizes optimal treatment selection. The ELTS score outperformed the Sokal score, the Euro, and the EUTOS score regarding risk group discrimination. The recent recommendation of the European LeukemiaNet for preferred use of the ELTS score was supported with significant statistical evidence.

Profound but Transient Changes in the Inflammatory Milieu of the Blood During Autologous Hematopoietic Stem Cell Transplantation

Little is known about the inflammatory milieu in the blood during autologous hematopoietic stem cell transplantation (AHSCT) and how it is affected by the stem cell mobilization, collection, and reinfusion and conditioning regimen. In this study, we analyzed 92 proteins connected to inflammation at 10 time points during and after AHSCT in 16 patients with multiple sclerosis (MS). Serum from 29 patients with newly diagnosed MS and 15 healthy controls were included for comparative analysis. There were no significant differences in inflammatory serum protein levels between patients with newly diagnosed MS and healthy controls, but 29 out of 73 detectable proteins were significantly altered between at least 2 adjacent sampling time points during AHSCT. The predominant changes occurred after the conditioning regimen had been administered, whereas stem cell mobilization, collection, and reinfusion appeared to have less impact. Two distinct response patterns could be discerned, likely representing loss of basal cytokine production and homeostasis. The analyzed serum proteins gradually returned to baseline levels after treatment, with no remaining differences at 3 months after AHSCT. We conclude that treatment with AHSCT has a major but transient impact on the inflammatory milieu of peripheral blood.

Immunological monitoring of newly diagnosed CML patients treated with bosutinib or imatinib first-line

Changes in the immune system induced by tyrosine kinase inhibitors (TKI) have been shown to positively correlate with therapy responses in chronic myeloid leukemia (CML). However, only a few longitudinal studies exist and no randomized comparisons between two TKIs have been reported. Therefore, we prospectively analyzed the immune system of newly diagnosed CML patients treated with imatinib (n = 20) or bosutinib (n = 13), that participated in the randomized BFORE trial (NCT02130557). Comprehensive immunophenotyping, plasma protein profiling, and functional assays to determine activation levels of T and NK cells were performed at diagnosis, 3, and 12 months after therapy start. All results were correlated with clinical parameters such as Sokal risk and BCR-ABL load measured according to IS%. At diagnosis, low Sokal risk CML patients had a higher frequency of cytotoxic cells (CD8 + T and NK cells), increased cytotoxic potential of NK cells and lower frequency of naïve and central memory CD4 + T cells. Further, soluble plasma protein profile divided patients into two distinct clusters with different disease burden at diagnosis. During treatment, BCR-ABL IS% correlated with immunological parameters such as plasma proteins, together with different memory subsets of CD4+ and CD8 + T cells. Interestingly, the proportion and cytotoxic potential of NK cells together with several soluble proteins increased during imatinib treatment. In contrast, no major immunological changes were observed during bosutinib treatment. In conclusion, imatinib and bosutinib were shown to have differential effects on the immune system in this randomized clinical trial. Increased number and function of NK cells were especially observed during imatinib therapy.

Primary results of the phase 4 BYOND study of bosutinib (BOS) for pretreated chronic phase (CP) chronic myeloid leukemia (CML)

7012

Background: The tyrosine kinase inhibitor (TKI) BOS is approved for patients (pts) with Philadelphia chromosome (Ph)+ CML resistant/intolerant to prior therapy and newly diagnosed pts in CP. Methods: The ongoing phase 4 BYOND study is further evaluating efficacy and safety of BOS (starting dose 500 mg/d) for CML resistant/intolerant to prior TKIs. Primary endpoint (not powered) in Ph+ CP CML cohorts is cumulative confirmed major cytogenetic response (MCyR) by 1 y. Results: Of 163 pts who received BOS, 156 had Ph+ CP CML (46, 61 and 49 after 1, 2 and 3 prior TKIs, respectively). Across Ph+ CP CML cohorts, 51.9% of pts were male; median age was 61 y. As of 1 y after last enrolled pt (median follow-up 30.4 mo), 56.4% remained on BOS. Median BOS duration was 23.7 mo and median dose intensity after adjustment due to adverse events (AEs) 313 mg/d. Of 144 evaluable pts with a valid baseline assessment, cumulative confirmed MCyR by 1 y was 71.5% (95% confidence interval [CI] 63.4–78.7). Cumulative complete cytogenetic response rate anytime on treatment was 81.3% (95% CI 73.9–87.3). Cumulative molecular response (MR) rates were high across lines of therapy (Table). 10 deaths occurred (5 on treatment); 1-y overall survival rate was 98.0%. No pt progressed to accelerated/blast phase on treatment. 25.0% discontinued BOS due to AEs and 5.1% due to insufficient response. Most common treatment-emergent AEs (TEAEs) were diarrhea (87.8%) and nausea (41.0%). Grade 3/4 TEAEs in > 10% of pts were diarrhea (16.7%) and increased alanine aminotransferase (ALT; 14.7%). The only TEAE leading to discontinuation in > 5% of pts was increased ALT (5.1%). Conclusions: Most pretreated pts with Ph+ CP CML had MCyR by 1 y with BOS; a substantial proportion achieved or preserved major MR (MMR) and deep MR in all therapy lines. Results further support BOS use for Ph+ CP CML resistant/intolerant to prior TKIs. Clinical trial information: NCT02228382. [Table: see text]

Advanced phase chronic myeloid leukaemia (CML) in the tyrosine kinase inhibitor era - a report from the Swedish CML register

OBJECTIVES

The primary goal in management of chronic phase (CP) chronic myeloid leukaemia (CML) is to prevent disease progression to accelerated phase (AP) or blast crisis (BC). We have evaluated progression rates in a decentralised healthcare setting and characterised patients progressing to AP/BC on TKI treatment.

METHODS

Using data from the Swedish CML register, we identified CP-CML patients diagnosed 2007-2011 who progressed to AP/BC within 2 yrs from diagnosis (n = 18) as well as patients diagnosed in advanced phase during 2007-2012 (n = 36) from a total of 544 newly diagnosed CML cases. We evaluated baseline characteristics, progression rates, outcome and adherence to guidelines for monitoring and treatment.

RESULTS

The cumulative progression rate at 2 yrs was 4.3%. All 18 progression cases had been treated with imatinib, and six progressed within 6 months. High-risk EUTOS score was associated to a higher risk of progression. Insufficient cytogenetic and/or molecular monitoring was found in 33%. Median survival after transformation during TKI treatment was 1.4 yrs. In those presenting with BC and AP, median survival was 1.6 yrs and not reached, respectively.

CONCLUSION

In this population-based setting, progression rates appear comparable to that reported from clinical trials, with similar dismal patient outcome. Improved adherence to CML guidelines may minimise the risk of disease progression.

Cardiovascular Events Associated With Use of Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia: A Population-Based Cohort Study

BACKGROUND

Tyrosine kinase inhibitors (TKIs) have increased survival dramatically for patients with chronic myeloid leukemia (CML), but continuous administration of these drugs may elicit long-term toxicity.

OBJECTIVE

To investigate the incidence of vascular events in patients with CML treated with first- and second-generation TKIs.

DESIGN

Retrospective cohort study using nationwide population-based registries.

SETTING

Sweden.

PATIENTS

All patients diagnosed with chronic-phase CML in Sweden from 2002 to 2012 and treated with a TKI, and 5 age- and sex-matched control individuals per patient.

MEASUREMENTS

Relative risks, expressed as incidence rate ratios comparing patients with control individuals, were calculated. Events per 1000 person-years were assessed in interdrug comparisons.

RESULTS

896 patients, 94.4% with documented TKI treatment, were followed for a median of 4.2 years. There were 54 arterial and 20 venous events in the CML cohort, corresponding to relative risks of 1.5 (95% CI, 1.1 to 2.1) and 2.0 (CI, 1.2 to 3.3), respectively. The event rate for myocardial infarction was higher in patients treated with nilotinib or dasatinib (29 and 19 per 1000 person-years, respectively) than in those receiving imatinib (8 per 1000 person-years), although data are limited and the CIs were wide and overlapped. Among 31 patients treated with a TKI who had myocardial infarction, 26 (84%) had at least 1 major cardiac risk factor diagnosed before the event occurred.

LIMITATIONS

Patients may have been exposed to multiple TKIs. Data on second- and third-generation TKIs were limited.

CONCLUSION

An increased risk for arterial and venous vascular events was seen in patients with CML treated with a TKI. Further study is needed to determine whether the risk for myocardial infarction increases with second-generation drugs.

PRIMARY FUNDING SOURCE

No external funding.

Increased prevalence of prior malignancies and autoimmune diseases in patients diagnosed with chronic myeloid leukemia

We recently reported an increased incidence of second malignancies in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors (TKI). To elucidate whether this increase may be linked, not to TKI but rather to a hereditary or acquired susceptibility to develop cancer, we estimated the prevalence of malignancies, autoimmune disease (AD) and chronic inflammatory disease (CID) in CML patients prior to their CML diagnosis. Nationwide population-based registers were used to identify patients diagnosed with CML in Sweden 2002-2012 and to estimate the prevalence of other malignancies, AD and CID prior to their CML diagnosis. For each patient with CML, five matched controls were selected from the general population. Conditional logistic regression was used to calculate odds ratios (OR). Nine hundred and eighty-four CML patients were assessed, representing more than 45 000 person-years of follow-up. Compared with matched controls, the prevalence of prior malignancies and AD was elevated in CML patients: OR 1.47 (95% confidence interval (CI) 1.20-1.82) and 1.55 (95% CI 1.21-1.98), respectively. No associations were detected between CML and previous CID. An increased prevalence of other malignancies and AD prior to the diagnosis of CML suggest that a hereditary or acquired predisposition to cancer and/or autoimmunity is involved in the pathogenesis of CML.

Assessment of bone marrow lymphocytic status during tyrosine kinase inhibitor therapy and its relation to therapy response in chronic myeloid leukaemia

PURPOSE

Tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukaemia have been reported to induce immunomodulatory effects. We aimed to assess peripheral blood (PB) and bone marrow (BM) lymphocyte status at the diagnosis and during different TKI therapies and correlate it with treatment responses.

METHODS

BM and PB samples were acquired from 105 first-line TKI-treated patients. Relative number of BM lymphocytes was evaluated from MGG-stained BM aspirates, and immunophenotypic analyses were performed with multicolour flow cytometry.

RESULTS

Early 3-month expansion of BM lymphocytes was found during all different TKIs (imatinib n = 71, 20 %; dasatinib n = 25, 21 %; nilotinib n = 9, 22 %; healthy controls n = 14, 12 %, p < 0.0001). Increased PB lymphocyte count was only observed during dasatinib therapy. The BM lymphocyte expansion was associated with early molecular response; patients with 3-month BCR-ABL1 <10 % showed higher lymphocyte counts than patients with BCR-ABL1 >10 % (23 vs. 17 %, p < 0.05). Detailed phenotypic analysis showed that BM lymphocyte expansion consisted of various lymphocyte subclasses, but especially the proportion of CD19+ B cells and CD3negCD16/56+ NK cells increased from diagnostic values. During dasatinib treatment, the lymphocyte balance in both BM and PB was shifted more to cytotoxic direction (increased CD8+CD57+ and CD8+HLA-DR+ cells, and low T regulatory cells), whereas no major immunophenotypic differences were observed between imatinib and nilotinib patients.

CONCLUSIONS

Early BM lymphocytosis occurs with all current first-line TKIs and is associated with better treatment responses. PB and BM immunoprofile during dasatinib treatment markedly differs from both imatinib- and nilotinib-treated patients.

Evaluation of Intracellular Signaling Downstream Chimeric Antigen Receptors

CD19-targeting CAR T cells have shown potency in clinical trials targeting B cell leukemia. Although mainly second generation (2G) CARs carrying CD28 or 4-1BB have been investigated in patients, preclinical studies suggest that third generation (3G) CARs with both CD28 and 4-1BB have enhanced capacity. However, little is known about the intracellular signaling pathways downstream of CARs. In the present work, we have analyzed the signaling capacity post antigen stimulation in both 2G and 3G CARs. 3G CAR T cells expanded better than 2G CAR T cells upon repeated stimulation with IL-2 and autologous B cells. An antigen-driven accumulation of CAR+ cells was evident post antigen stimulation. The cytotoxicity of both 2G and 3G CAR T cells was maintained by repeated stimulation. The phosphorylation status of intracellular signaling proteins post antigen stimulation showed that 3G CAR T cells had a higher activation status than 2G. Several proteins involved in signaling downstream the TCR were activated, as were proteins involved in the cell cycle, cell adhesion and exocytosis. In conclusion, 3G CAR T cells had a higher degree of intracellular signaling activity than 2G CARs which may explain the increased proliferative capacity seen in 3G CAR T cells. The study also indicates that there may be other signaling pathways to consider when designing or evaluating new generations of CARs.

The tyrosine kinase inhibitors imatinib and dasatinib reduce myeloid suppressor cells and release effector lymphocyte responses

Immune escape mechanisms promote tumor progression and are hurdles of cancer immunotherapy. Removing immunosuppressive cells before treatment can enhance efficacy. Tyrosine kinase inhibitors (TKI) may be of interest to combine with immunotherapy, as it has been shown that the inhibitor sunitinib reduces myeloid suppressor cells in patients with renal cell carcinoma and dasatinib promotes expansion of natural killer-like lymphocytes in chronic myeloid leukemia (CML). In this study, the capacity of dasatinib and imatinib to reduce myeloid suppressor cells and to induce immunomodulation in vivo was investigated ex vivo. Samples from CML patients treated with imatinib (n = 18) or dasatinib (n = 14) within a Nordic clinical trial (clinicalTrials.gov identifier: NCT00852566) were investigated for the presence of CD11b(+)CD14(-)CD33(+) myeloid cells and inhibitory molecules (arginase I, myeloperoxidase, IL10) as well as the presence of natural killer cells, T cells (naïve/memory), and stimulatory cytokines (IL12, IFNγ, MIG, IP10). Both imatinib and dasatinib decreased the presence of CD11b(+)CD14(-)CD33(+) myeloid cells as well as the inhibitory molecules and the remaining myeloid suppressor cells had an increased CD40 expression. Monocytes also increased CD40 after therapy. Moreover, increased levels of CD40, IL12, natural killer cells, and experienced T cells were noted after TKI initiation. The presence of experienced T cells was correlated to a higher IFNγ and MIG plasma concentration. Taken together, the results demonstrate that both imatinib and dasatinib tilted the immunosuppressive CML tumor milieu towards promoting immune stimulation. Hence, imatinib and dasatinib may be of interest to combine with cancer immunotherapy.

Clonal distribution of BCR-ABL1 mutations and splice isoforms by single-molecule long-read RNA sequencing

Background

The evolution of mutations in the BCR-ABL1 fusion gene transcript renders CML patients resistant to tyrosine kinase inhibitor (TKI) based therapy. Thus screening for BCR-ABL1 mutations is recommended particularly in patients experiencing poor response to treatment. Herein we describe a novel approach for the detection and surveillance of BCR-ABL1 mutations in CML patients.

Methods

To detect mutations in the BCR-ABL1 transcript we developed an assay based on the Pacific Biosciences (PacBio) sequencing technology, which allows for single-molecule long-read sequencing of BCR-ABL1 fusion transcript molecules. Samples from six patients with poor response to therapy were analyzed both at diagnosis and follow-up. cDNA was generated from total RNA and a 1,6 kb fragment encompassing the BCR-ABL1 transcript was amplified using long range PCR. To estimate the sensitivity of the assay, a serial dilution experiment was performed.

Results

Over 10,000 full-length BCR-ABL1 sequences were obtained for all samples studied. Through the serial dilution analysis, mutations in CML patient samples could be detected down to a level of at least 1%. Notably, the assay was determined to be sufficiently sensitive even in patients harboring a low abundance of BCR-ABL1 levels. The PacBio sequencing successfully identified all mutations seen by standard methods. Importantly, we identified several mutations that escaped detection by the clinical routine analysis. Resistance mutations were found in all but one of the patients. Due to the long reads afforded by PacBio sequencing, compound mutations present in the same molecule were readily distinguished from independent alterations arising in different molecules. Moreover, several transcript isoforms of the BCR-ABL1 transcript were identified in two of the CML patients. Finally, our assay allowed for a quick turn around time allowing samples to be reported upon within 2 days.

Conclusions

In summary the PacBio sequencing assay can be applied to detect BCR-ABL1 resistance mutations in both diagnostic and follow-up CML patient samples using a simple protocol applicable to routine diagnosis. The method besides its sensitivity, gives a complete view of the clonal distribution of mutations, which is of importance when making therapy decisions.

Dasatinib induces fast and deep responses in newly diagnosed chronic myeloid leukaemia patients in chronic phase: clinical results from a randomised phase-2 study (NordCML006)

We randomised 46 newly diagnosed patients with chronic myeloid leukaemia (median age 56) to receive dasatinib 100 mg QD or imatinib 400 mg QD and report outcome as an intention-to-treat analysis with 36 months follow-up. Early cytogenetic and molecular responses were superior in the dasatinib group, with a tendency that imatinib patients caught up with time. For instance, MR^3.0 was reached at 3 months in 36% vs. 8% (P = 0.02), at 12 months in 81% vs. 46% (P = 0.02) and at 18 months in 73% vs. 65% (n.s.) of the patients in the two groups. In contrast, MR^4.5 was consistently superior in the dasatinib group at all time points from 6 months onwards, reaching 61% vs. 21% (P < 0.05) at 36 months. Sixty-four vs. 71% of the patients in the dasatinib and imatinib arms, respectively, remained on assigned drug. Dasatinib dose was frequently reduced, but with maintained excellent effect. One imatinib patient progressed to blastic phase, but no CML-related deaths occurred. In conclusion, our data compare favourably with those of the dasatinib registration study, DASISION. The fast and deep molecular responses induced by dasatinib compared with imatinib may be exploited to increase the proportion of patients who can achieve a treatment-free remission after treatment discontinuation.

Both CD4+ FoxP3+ and CD4+ FoxP3- T cells from patients with B-cell malignancy express cytolytic markers and kill autologous leukaemic B cells in vitro

Cytotoxic CD4(+) T cells have been found in patients with chronic lymphocytic leukaemia (CLL) and seem to be involved in the regulation of malignant B cells. The CD4(+) T regulatory cells (Tregs) can regulate various immune cells, including B cells, by inducing their apoptosis. Hence, different subgroups of CD4(+) T cells may be involved in the regulation of malignant B cells. In this study, the cytotoxic phenotype and function of various CD4(+) T-cell subgroups were investigated in patients with B-cell malignancies. Peripheral blood was collected from patients with CLL, various B-cell lymphomas, healthy adult donors, children with precursor B-cell acute lymphoblastic leukaemia (pre-B ALL) and from healthy children. CD4(+) T cells (CD3(+) CD4(+)  FoxP3(-)), Tregs (CD3(+) CD4(+) CD127(low) FoxP3(+)) and CD127(high) FoxP3(+) T cells (CD3(+) CD4(+) CD127(high) FoxP3(+)) were analysed for their expression of the cytolytic markers CD107a and Fas ligand. Patients with CLL had increased CD107a expression on all tested T-cell subgroups compared with healthy donors. Similar results were found in patients with B-cell lymphomas whereas the CD107a expression in children with pre-B ALL was no different from that in healthy controls. Fas ligand expression was similar between patient cells and cells of healthy donors. CD4(+) T cells and Tregs from patients with CLL and healthy donors were subsequently purified and cultured in vitro with autologous B cells. Both subgroups lysed B cells and killing was confirmed by granzyme ELISAs. In conclusion, cytotoxic populations of CD4(+) T cells, including Tregs, are present in patients with B-cell malignancy and may be an important factor in immune-related disease control.

T regulatory cells control T-cell proliferation partly by the release of soluble CD25 in patients with B-cell malignancies

Interleukin-2 (IL-2) is one of the most studied cytokines driving T-cell proliferation, activation and survival. It binds to the IL-2 receptor consisting of three chains, the α (CD25), β and common γ (γc). The binding of the CD25 chain to IL-2 is necessary to expose high-affinity binding sites for the β and γc chains, which, in turn, are responsible for downstream signalling. A high level of soluble CD25 (sCD25) has been associated with a poor prognosis in patients with non-Hodgkin's lymphoma. The function and source of origin of this soluble receptor is not well investigated. In the present study we hypothesized that T regulatory (Treg) cells may release CD25 to act as a decoy receptor for IL-2, thereby depriving T-effector cells of IL-2. Peripheral blood from patients with B-cell malignancies (n = 26) and healthy controls (n = 27) was investigated for the presence and function of FoxP3(+) Treg cells and sCD25 by multi-colour flow cytometry and enzyme-linked immunosorbent assay. Further, the proliferative capacity of T cells was evaluated with or without the presence of recombinant sCD25. The results demonstrate that Treg cells from patients had lower CD25 expression intensity and that they released CD25 in vitro. Further, high levels of Treg cells correlated with sCD25 plasma concentration. Recombinant sCD25 could suppress T-cell proliferation in vitro. In conclusion, the release of sCD25 by Treg cells may be a mechanism to deprive IL-2 and thereby inhibit anti-tumour T-cell responses.

Molecular monitoring and mutation analysis of patients with advanced phase CML and Ph+ ALL receiving dasatinib

As a result of the excellent responses achieved in chronic phase chronic myeloid leukemia since the introduction of imatinib, sensitive techniques such as reverse transcriptase real-time PCR are warranted to monitor patients receiving tyrosine kinase inhibitors (TKI). Our objective was to determine the value of molecular monitoring Ph-positive leukemias under dasatinib treatment. We used real-time PCR and ABL1 kinase domain sequencing on sequential samples from 11 patients with Philadelphia-positive leukemias who received dasatinib. We were able to detect pre-existing mutations in the kinase domain of BCR-ABL1 in four patients, particularly in patients with high BCR-ABL1 transcript levels. Most mutations disappeared with dasatinib, however, in five patients a clone with T315I appeared during dasatinib treatment. We conclude that sensitive molecular monitoring with real-time PCR for BCR-ABL1 transcripts and mutation screening of the ABL1 kinase domain of patients with Philadelphia-positive leukemias are valuable for patient management, however, mutation findings should be interpreted with caution, as mutant clones not always behave in vivo as predicted by in vitro assays.

Gene expression analysis identifies a genetic signature potentially associated with response to α-IFN in chronic phase CML patients

Microarray-based gene expression analysis was performed on diagnostic chronic phase CML patient samples prior to interferon treatment. Fifteen patient samples corresponding to six cytogenetic responders and nine non-responders were included. Genes differentially expressed between responder and non-responder patients were listed and a subsequent leave-one-out cross validation (LOOV) procedure showed that the top 20 genes allowed the highest prediction accuracy. The relevant genes were quantified by real-time PCR that supported the microarray results. We conclude that it might be possible to use gene expression analysis to predict future response to interferon in CML diagnostic samples.

Successful mobilization of Ph-negative blood stem cells with intensive chemotherapy + G-CSF in patients with chronic myelogenous leukemia in first chronic phase

The aim of the study was to investigate the feasibility of mobilizing Philadelphia chromosome negative (Ph-) blood stem cells (BSC) with intensive chemotherapy and lenograstim (G-CSF) in patients with CML in first chronic phase (CP1). During 1994-1999 12 centers included 37 patients <56 years. All patients received 6 months' IFN, stopping at median 36 (1-290) days prior to the mobilization chemotherapy. All received one cycle of daunorubicin 50 mg/m2 and 1 hour infusion on days 1-3, and cytarabine (ara-C) 200 mg/m2 24 hours' i.v. infusion on days 1-7 (DA) followed by G-CSF 526 microg s.c. once daily from day 8 after the start of chemotherapy. Leukaphereses were initiated when the number of CD 34+ cells was >5/microl blood. Patients mobilizing poorly could receive a 4-day cycle of chemotherapy with mitoxantrone 12 mg/m2/day and 1 hour i.v infusion, etoposide 100 mg/m2/day and 1 hour i.v. infusion and ara-C 1 g/m2/twice a day with 2 hours' i.v infusion (MEA) or a second DA, followed by G-CSF 526 microg s.c once daily from day 8 after the start of chemotherapy. Twenty-seven patients received one cycle of chemotherapy and G-CSF, whereas 10 were mobilized twice. Twenty-three patients (62%) were successfully (MNC >3.5 x 10(8)/kg, CFU-GM >1.0 x 10(4)/kg, CD34+ cells >2.0 x 10(6)/kg and no Ph+ cells in the apheresis product) [n = 16] or partially successfully (as defined above but 1-34% Ph+ cells in the apheresis product) [n = 7] mobilized. There was no mortality during the mobilization procedure. Twenty-one/23 patients subsequently underwent auto-SCT. The time with PMN <0.5 x 10(9)/l was 10 (range 7-49) and with platelets <20 x 10(9)/l was also 10 (2-173) days. There was no transplant related mortality. The estimated 5-year overall survival after auto-SCT was 68% (95% CI 47 - 90%), with a median follow-up time of 5.2 years.We conclude that in a significant proportion of patients with CML in CP 1, intensive chemotherapy combined with G-CSF mobilizes Ph- BSC sufficient for use in auto-SCT.

Imatinib activity in vitro in tumor cells from patients with chronic myeloid leukemia in chronic phase and blast crisis

The aims of this study were to evaluate the feasibility of using the non-clonogenic fluorometric microculture cytotoxicity assay in drug sensitivity testing of tumor cells from patients with chronic myeloid leukemia. In nine samples (six chronic phase, three blast crisis), the drug sensitivities in tumor cells from blood versus from bone marrow and fresh tumor cells versus cryopreserved were compared. In 26 samples obtained in chronic phase (pretreatment), in six samples from patients in blast crisis and in the K 562 cell line, the activity of imatinib alone and in combination with cytarabine, vincristine, daunorubicin, interferon, arsenic trioxide and homoharringtonine was evaluated. All chronic myeloid leukemia chronic phase samples were sensitive to imatinib, with a mean IC50 at 10.3 mumol/l. The chronic myeloid leukemia samples from blast crisis (n=6) were significantly more sensitive to imatinib than the samples from chronic phase (n=26) (P<0.05), with an IC50 mean at 0.4 mumol/l. In blast crisis samples, significant positive interaction effects were observed between imatinib and all other tested drugs except for interferon. In chronic phase samples, interferon, daunorubicin and arsenic trioxide were the drugs with the highest frequency of positive interactions with imatinib (P<0.05). We conclude that the fluorometric microculture cytotoxicity assay may be a useful method for drug sensitivity testing in chronic myeloid leukemia patient samples from both chronic phase and blast crisis, and that testing primary tumor cells may have advantages over cell line studies. Imatinib shows a higher in vitro activity and more positive drug interactions in cells from blast crisis than chronic phase chronic myeloid leukemia patients. Combinations between imatinib and interferon, daunorubicin and arsenic trioxide may be interesting for future clinical trials in patients with chronic myeloid leukemia chronic phase.

The impact of RNA stabilization on minimal residual disease assessment in chronic myeloid leukemia

BACKGROUND AND OBJECTIVES

Accurate quantification of BCR-ABL mRNA is of critical importance for managing patients with chronic myeloid leukemia (CML) who are receiving imatinib therapy. RNA degradation thus constitutes a potential problem for laboratories quantifying minimal residual disease (MRD). Patients' samples that take a long time to be transported from the hospital to the analyzing laboratory may be subject to RNA degradation with a corresponding loss in sensitivity and possible generation of false negative results. Recently, RNA preservation systems have been developed in order to improve RNA stability. The aim of the present study was to investigate such a system.

DESIGN AND METHODS

We evaluated the performance of the PAXgene Blood RNA Kit in follow-up CML peripheral blood samples and compared the results to those from unstabilized parallel Trizol extracted samples. The different sample processing methods were evaluated by real-time polymerase chain reaction (PCR) analysis.

RESULTS

RNA isolated with the PAXgene system gave a superior yield per milliliter of blood than did the routine Trizol extraction method. However, although of comparable quality, the RNA did not PCR-amplify as efficiently as equal amounts of RNA from routinely processed samples. Therefore, RNA processed with the PAXgene system showed decreased sensitivity for MRD detection, resulting in false negative results. The sensitivity was comparable to that of samples processed routinely 20-30 hours after phlebotomy.

INTERPRETATION AND CONCLUSIONS

We conclude that routinely processed, i.e. unstabilized, peripheral blood that reaches the laboratory and is processed within 30 hours is preferable for MRD detection. Optimal results were achieved with fresh samples processed within 5 hours with the Trizol method. However, RNA stabilization may be useful if sample transit is expected to exceed 30 hours.

Comparison of busulphan, hydroxyurea and allogeneic bone marrow transplantation (BMT) in chronic myeloid leukaemia: BMT prolongs survival

INTRODUCTION

Whether busulphan-treated patients develop blastic transformation earlier than hydroxyurea treated has been a controversial issue. In a randomised prospective study, we examined the busulphan versus hydroxyurea influence on time to blast crisis and on survival. When we opened our study in 1984, the clinical benefit of allogeneic bone marrow transplantation (BMT) was not well known; to follow up the long-time outcome of this treatment was therefore of great interest.

MATERIALS AND METHODS

Previously untreated CML patients were randomly started on either hydroxyurea (30 mg/kg/day) or busulphan (0.1 mg/kg/day). The end points of the study were overall survival and time to blast crisis. A total of 26 patients subsequently underwent BMT.

RESULTS

A total of 179 patients were randomised, 90 of hydroxyurea, and 89 to busulphan treatment. There was no significant difference in survival between hydroxyurea- and busulphan-treated patients (P = 0.46); median survival was 3.5 and 3.2 years, respectively. In all, 85 of the patients were subsequently diagnosed with blast crisis, 41 in the busulphan and 44 in the hydroxyurea group. There was no significant difference between the two groups (P = 0.91). The 26 patients who were allotransplanted survived significantly longer than those who were not transplanted (P = 0.0001). The 5-year-survival rates were 50 and 22% and the 10-year-survival rates were 46 and 2%, respectively. The median survival was 4.7 years for the transplanted and 3.3 years for the nontransplanted patients.

CONCLUSION

We did not find any difference between hydroxyurea and busulphan treatment, either in overall survival or in blast crisis-free survival; transplanted patients survived significantly longer than nontransplanted patients.

Manifold-assisted reverse transcription-PCR with real-time detection for measurement of the BCR-ABL fusion transcript in chronic myeloid leukemia patients

BACKGROUND

BCR-ABL fusion mRNA expression in bone marrow or peripheral blood can be used as a measure of minimal residual disease in patients with chronic myeloid leukemia (CML).

METHODS

We used an oligo(dT)-coated manifold support to capture the mRNA directly from the cell lysate. After reverse transcription, the cDNA was eluted from the manifold support, and BCR-ABL and GAPDH mRNAs were quantified in real time using the TaqMan fluorogenic detection system.

RESULTS

The detection limit of the method was one positive K562 cell among 10(5) negative cells. GAPDH was chosen as a reference gene based on the low variation between samples from different stages of the disease and the low signal in the absence of reverse transcription. The day-to-day variation of the method (CV) was 32%. In 43 blood samples from 13 CML patients, mRNA quantification agreed well with cytogenetic data.

CONCLUSIONS

The proposed procedure constitutes a reproducible and sensitive BCR-ABL mRNA quantification method and is suitable to monitor minimal residual disease in CML patients.