SOCS-2 gene expression at diagnosis has been suggested as a predictor of clinical outcome in chronic myeloid leukemia (CML). In this study SOCS-2 and GUS expression levels were determined by real-time PCR in pretherapeutic samples at diagnosis. First, three patient groups were compared after assessment at 48 months: optimal molecular responders (n = 35), patients with resistance to imatinib (n = 28), and blast crisis patients (n = 27). A significant difference in SOCS-2 gene expression at diagnosis was observed comparing blast crisis vs. resistant patients (p = 0.042) and optimal responders (p = 0.010). Second, a validation sample of consecutively randomized patients (n = 123) was investigated. No discriminative SOCS-2 gene expression cutoff could be derived to predict molecular or cytogenetic response, progression-free or overall survival. Although SOCS-2 gene was differentially expressed at the time of diagnosis in blast crisis patients when compared to other groups, a prognostic impact in consecutively randomized patients was not observed.

Treatment of chronic myeloid leukemia (CML) has been profoundly improved by the introduction of tyrosine kinase inhibitors (TKIs). Long-term survival with imatinib is excellent with a 8-year survival rate of ∼88%. Long-term toxicity of TKI treatment, especially carcinogenicity, has become a concern. We analyzed data of the CML study IV for the development of secondary malignancies. In total, 67 secondary malignancies were found in 64 of 1525 CML patients in chronic phase treated with TKI (n=61) and interferon-α only (n=3). The most common malignancies (n⩾4) were prostate, colorectal and lung cancer, non-Hodgkin's lymphoma (NHL), malignant melanoma, non-melanoma skin tumors and breast cancer. The standardized incidence ratio (SIR) for all malignancies excluding non-melanoma skin tumors was 0.88 (95% confidence interval (0.63-1.20)) for men and 1.06 (95% CI 0.69-1.55) for women. SIRs were between 0.49 (95% CI 0.13-1.34) for colorectal cancer in men and 4.29 (95% CI 1.09-11.66) for NHL in women. The SIR for NHL was significantly increased for men and women. An increase in the incidence of secondary malignancies could not be ascertained. The increased SIR for NHL has to be considered and long-term follow-up of CML patients is warranted, as the rate of secondary malignancies may increase over time.

Tyrosine kinase inhibitors (TKI) have changed the natural course of chronic myeloid leukemia (CML). With the advent of second-generation TKI safety and efficacy issues have gained interest. The randomized CML - Study IV was used for a long-term evaluation of imatinib (IM). 1503 patients have received IM, 1379 IM monotherapy. After a median observation of 7.1 years, 965 patients (64%) still received IM. At 10 years, progression-free survival was 82%, overall survival 84%, 59% achieved MR 5 , 72% MR 4.5 , 81% MR 4 , 89% major molecular remission and 92% MR 2 (molecular equivalent to complete cytogenetic remission). All response levels were reached faster with IM800 mg except MR 5 . Eight-year probabilities of adverse drug reactions (ADR) were 76%, of grades 3–4 22%, of non-hematologic 73%, and of hematologic 28%. More ADR were observed with IM800 mg and IM400 mg plus interferon α (IFN). Most patients had their first ADR early with decreasing frequency later on. No new late toxicity was observed. ADR to IM are frequent, but mostly mild and manageable, also with IM 800 mg and IM 400 mg+IFN. The deep molecular response rates indicate that most patients are candidates for IM discontinuation. After 10 years, IM continues to be an excellent initial choice for most patients with CML.

We studied the influence of comorbidities on remission rate and overall survival (OS) in patients with chronic myeloid leukemia (CML). Participants of the CML Study IV, a randomized 5-arm trial designed to optimize imatinib therapy, were analyzed for comorbidities at diagnosis using the Charlson Comorbidity Index (CCI); 511 indexed comorbidities were reported in 1519 CML patients. Age was an additional risk factor in 863 patients. Resulting CCI scores were as follows: CCI 2, n = 589; CCI 3 or 4, n = 599; CCI 5 or 6, n = 229; and CCI ≥ 7, n = 102. No differences in cumulative incidences of accelerated phase, blast crisis, or remission rates were observed between patients in the different CCI groups. Higher CCI was significantly associated with lower OS probabilities. The 8-year OS probabilities were 93.6%, 89.4%, 77.6%, and 46.4% for patients with CCI 2, 3 to 4, 5 to 6, and ≥7, respectively. In multivariate analysis, CCI was the most powerful predictor of OS, which was still valid after removal of its age-related components. Comorbidities have no impact on treatment success but do have a negative effect on OS, indicating that survival of patients with CML is determined more by comorbidities than by CML itself. OS may therefore be inappropriate as an outcome measure for specific CML treatments. The trial was registered at www.clinicaltrials.gov as #NCT00055874.

Major route additional cytogenetic aberrations (ACA) at diagnosis of chronic myeloid leukaemia (CML) indicate an increased risk of progression and shorter survival. Since major route ACA are almost always unbalanced, it is unclear whether other unbalanced ACA at diagnosis also confer an unfavourable prognosis. On the basis of 1348 Philadelphia chromosome-positive chronic phase patients of the randomized CML study IV, we examined the impact of unbalanced minor route ACA at diagnosis versus major route ACA on prognosis. At diagnosis, 1175 patients (87.2 %) had a translocation t(9;22)(q34;q11) and 74 (5.5 %) a variant translocation t(v;22) only, while a loss of the Y chromosome (−Y) was present in addition in 44 (3.3 %), balanced or unbalanced minor route ACA each in 17 (1.3 %) and major route ACA in 21 (1.6 %) cases. Patients with unbalanced minor route ACA had no significantly different cumulative incidences of complete cytogenetic remission or major molecular remission and no significantly different progression-free survival (PFS) or overall survival (OS) than patients with t(9;22), t(v;22), −Y and balanced minor route karyotypes. In contrast, patients with major route ACA had a shorter OS and PFS than all other groups (all pairwise comparisons to each of the other groups: p ≤ 0.015). Five-year survival probabilities were for t(9;22) 91.4 % (95 % CI 89.5–93.1), t(v; 22) 87 % (77.2–94.3), −Y 89.0 % (76.7–97.0), balanced 100 %, unbalanced minor route 92.3 % (72.4–100) and major route 52.2 % (28.2–75.5). We conclude that only major route, but not balanced or unbalanced minor route ACA at diagnosis, has a negative impact on prognosis of CML.

To date risk stratification in acute promyelocytic leukemia (APL) is based on highly dynamic leukocyte and platelet counts only. To identify a more robust risk stratification model, a molecular risk score was developed based on expression levels of the genes BAALC, ERG and WT1. Hereby, the main focus was on prediction of relapse. The integrative risk score divided patients into two groups with highly significant differences in outcome. It discriminated a high risk group with a high incidence of relapse successfully from a low risk group with no APL-related events after achievement of first remission. Especially the concurrent presence of molecular risk factors showed to be a negative prognostic factor in APL. The molecular risk score might be a promising approach to guide monitoring of APL patients and therapeutic decisions in the future.

The assessment of response to tyrosine kinase inhibitor (TKI) treatment in chronic myeloid leukemia (CML) does not only reflect tumor burden at a given time but has been shown to be linked to long-term survival outcomes as well. Therefore, the quantification of molecular or cytogenetic response as early as 3 months on treatment allows a prognostic stratification of a patient's individual risk. With competing TKI regimens available, a timely switch of treatment can be considered if unfavorable outcome has to be expected due to early response failure. Numerous studies have demonstrated the association of long-term outcome with early response for first-line treatment with imatinib, with second-generation TKI and for second-line TKI treatment as well.

The vast majority of chronic myeloid leukemia patients express a BCR-ABL1 fusion gene mRNA encoding a 210 kDa tyrosine kinase which promotes leukemic transformation. A possible differential impact of the corresponding BCR-ABL1 transcript variants e13a2 (“b2a2”) and e14a2 (“b3a2”) on disease phenotype and outcome is still a subject of debate. A total of 1105 newly diagnosed imatinib-treated patients were analyzed according to transcript type at diagnosis (e13a2, n=451; e14a2, n=496; e13a2+e14a2, n=158). No differences regarding age, sex, or Euro risk score were observed. A significant difference was found between e13a2 and e14a2 when comparing white blood cells (88 vs. 65 × 109/L, respectively; P<0.001) and platelets (296 vs. 430 × 109/L, respectively; P<0.001) at diagnosis, indicating a distinct disease phenotype. No significant difference was observed regarding other hematologic features, including spleen size and hematologic adverse events, during imatinib-based therapies. Cumulative molecular response was inferior in e13a2 patients (P=0.002 for major molecular response; P<0.001 for MR4). No difference was observed with regard to cytogenetic response and overall survival. In conclusion, e13a2 and e14a2 chronic myeloid leukemia seem to represent distinct biological entities. However, clinical outcome under imatinib treatment was comparable and no risk prediction can be made according to e13a2 versus e14a2 BCR-ABL1 transcript type at diagnosis. (clinicaltrials.gov identifier:00055874)

In the face of competing tyrosine kinase inhibitors (TKIs), identification of chronic myeloid leukemia (CML) patients expecting favorable response to second-line treatment is warranted. At the time of imatinib resistance, the investigation of multidrug-resistance protein 1 (MDR1) and BCR-ABL yielded the following results: (i) Patients with high MDR1 transcript levels showed superior response at 48 months as compared with low-level MDR1 patients: major molecular response (MMR) in 41% vs 16% (P=0.014), complete cytogenetic response (CCyR) in 58% vs 39% (P=0.044), and progression-free survival (PFS) in 67% vs 46% (P=0.032). (ii) Patients with BCR-ABL(IS) <28% achieved higher MMR rates (48% vs 21%, P=0.009). (iii) PFS at 48 months was associated with in vitro resistance of BCR-ABL kinase domain mutations: 63% (no mutation) vs 61% (sensitive, intermediately sensitive or unknown IC50 (median inhibitory concentration)) vs 23% (resistant, P=0.01). (iv) Single-nucleotide polymorphisms (SNPs) at positions 1236 and 2677 were associated with higher MDR1 expression in comparison to wild type. (v) Nilotinib was able to impede proliferation of MDR1-overexpressing imatinib-resistant cells. High MDR1 gene expression might identify patients whose mode of imatinib resistance is essentially determined by increased efflux activity of MDR1 and therefore can be overcome by second-line nilotinib treatment.

The impact of imatinib dose on response rates and survival in older patients with chronic myeloid leukemia in chronic phase has not been studied well. We analyzed data from the German CML-Study IV, a randomized five-arm treatment optimization study in newly diagnosed BCR-ABL-positive chronic myeloid leukemia in chronic phase. Patients randomized to imatinib 400 mg/day (IM400) or imatinib 800 mg/day (IM800) and stratified according to age (≥65 years vs. <65 years) were compared regarding dose, response, adverse events, rates of progression, and survival. The full 800 mg dose was given after a 6-week run-in period with imatinib 400 mg/day. The dose could then be reduced according to tolerability. A total of 828 patients were randomized to IM400 or IM800. Seven hundred eighty-four patients were evaluable (IM400, 382; IM800, 402). One hundred ten patients (29 %) on IM400 and 83 (21 %) on IM800 were ≥65 years. The median dose per day was lower for patients ≥65 years on IM800, with the highest median dose in the first year (466 mg/day for patients ≥65 years vs. 630 mg/day for patients <65 years). Older patients on IM800 achieved major molecular remission and deep molecular remission as fast as younger patients, in contrast to standard dose imatinib with which older patients achieved remissions much later than younger patients. Grades 3 and 4 adverse events were similar in both age groups. Five-year relative survival for older patients was comparable to that of younger patients. We suggest that the optimal dose for older patients is higher than 400 mg/day. ClinicalTrials.gov identifier: NCT00055874

Early assessment of response at 3 months of tyrosine kinase inhibitor treatment has become an important tool to predict favorable outcome. We sought to investigate the impact of relative changes of BCR-ABL transcript levels within the initial 3 months of therapy. In order to achieve accurate data for high BCR-ABL levels at diagnosis, beta glucuronidase (GUS) was used as a reference gene. Within the German CML-Study IV, samples of 408 imatinib-treated patients were available in a single laboratory for both times, diagnosis and 3 months on treatment. In total, 301 of these were treatment-naïve at sample collection. Results: (i) with regard to absolute transcript levels at diagnosis, no predictive cutoff could be identified; (ii) at 3 months, an individual reduction of BCR-ABL transcripts to the 0.35-fold of baseline level (0.46-log reduction, that is, roughly half-log) separated best (high risk: 16% of patients, 5-year overall survival (OS) 83% vs 98%, hazard ratio (HR) 6.3, P =0.001); (iii) at 3 months, a 6% BCR-ABL IS cutoff derived from BCR-ABL/GUS yielded a good and sensitive discrimination (high risk: 22% of patients, 5-year OS 85% vs 98%, HR 6.1, P =0.002). Patients at risk of disease progression can be identified precisely by the lack of a half-log reduction of BCR-ABL transcripts at 3 months.

Since the advent of tyrosine kinase inhibitors, the impact of age on outcome of chronic myeloid leukemia (CML) patients has changed. We therefore analyzed patients from the randomized CML study IV to investigate disease manifestations and outcome in different age groups. One thousand five hundred twenty-four patients with BCR-ABL-positive chronic phase CML were divided into four age groups: (1) 16–29 years, n = 120; (2) 30–44 years, n = 383; (3) 45–59 years, n = 495; and (4) ≥60 years, n = 526. Group 1 (adolescents and young adults (AYAs)) presented with more aggressive disease features (larger spleen size, more frequent symptoms of organomegaly, higher white blood count, higher percentage of peripheral blasts and lower hemoglobin levels) than the other age groups. In addition, a higher rate of patients with BCR-ABL transcript levels >10 % on the international scale (IS) at 3 months was observed. After a median observation time of 67.5 months, no inferior survival and no differences in cytogenetic and molecular remissions or progression rates were observed. We conclude that AYAs show more aggressive features and poor prognostic indicators possibly indicating differences in disease biology. This, however, does not affect outcome.

Purpose Chronic myeloid leukemia (CML) patients are monitored by both cytogenetic and molecular assessments, although present guidelines appear to switch from cytogenetic to molecular criteria. Due to the increasing use of molecular measurements, it was the aim of this work to identify a BCR-ABL level according to the international scale (BCR-ABL IS ) as an equivalent substitute for complete cytogenetic remission (CCyR). Methods In total, 1,329 paired data from 557 patients of the German CML-Study IV were evaluated. The data set was divided into a learning set and a validation set. The best cutoff was determined applying a minimal p value approach to the Fisher test. Results In the learning set, we found BCR-ABL IS values between 0.2 and 1.1 % were well suited for predicting a CCyR. In the validation set, the cutoff level of 1 % led to a mean concordance rate of 90.1 %. Conclusions Our results suggest that there is no one-to-one cutoff for BCR-ABL IS representing CCyR, but we advise to use the 1 % BCR-ABL IS in order to avoid misclassification of CCyR patients.

Introduction: Risk stratification in acute promyelocytic leukemia (APL) is based on the easily accessible Sanz-Score, which combines leukocyte and platelet counts at initial diagnosis. This score showed significant differences in relapse-free survival (RFS) of APL patients in various studies and is currently used to determine whether a patient can be treated with ATRA and ATO alone or needs additional chemotherapy. However, to make therapeutic decisions based on a risk stratification system derived from the endpoint RFS bears the drawback that relapses are rare in APL and most events are deaths in complete remission (CR), which can be therapy related (e.g. toxicity). The cumulative incidence of relapse (CIR) therefore seems to be a better parameter for decision making with regard to therapy intensity. In this study, we optimized a risk score combining data on gene expression of BAALC (brain and acute leukemia, cytoplasmic), ERG (ets’ related gene) and WT1 (Wilms’ tumor 1) to retrospectively predict the CIR of APL patients. Methods: Data on BAALC, ERG and WT1 expression levels of 79 patients with newly diagnosed APL were obtained from bone marrow mononuclear cells using quantitative real-time RT-PCR in preceding studies. The following gene expression levels were identified as negative risk factors: BAALC expression ≥25th percentile (BAALChigh), ERG expression >75th percentile (ERGhigh) and WT1 expression ≤25th percentile or ≥75th percentile (WT1low or high). As ERGhigh was the only independent predictor for relapse in multivariate analysis with a hazard ratio (HR) of 11.6, its predictive weight was regarded superior, respectively . Cut-off analyses were performed to determine the optimal ERG expression level cut-off for risk of relapse. Accordingly, the new cut-off for high ERG expression was set at ≥62nd percentile (optimized ERGhigh: optERGhigh; Sensitivity: 1.0, Specificity: 0.71). A combined risk score was developed as follows: For the presence of one of the mentioned risk factors, one scoring point was assigned to a respective patient, i.e. a maximum of 3 points (one point for BAALChigh, optERGhigh and WT1low or high, respectively) and a minimum of 0 points (i.e. presenting with none of the aforementioned risk factors) could be allocated to one patient. Accordingly, patients were divided into two risk groups: 34 patients scored 0-1 points and 45 patients scored 2-3 points. CIR, overall survival (OS) and RFS were calculated using the Kaplan-Meier method and a log-rank test was used to compare differences between the two risk groups (p Results: Patients with 2-3 points had a CIR of 18% at 10 years of follow-up whereas none of the patients with 0-1 points suffered a relapse (CIR: 0%; p=0.02; Fig. 1). All relapses occurred between 8.4 months and 3.5 years after first CR. Moreover, OS and RFS also differed significantly between the two risk groups: OS was 53% for patients with 2-3 points vs. 85% for patients with 0-1 points (p=0.004); RFS was 49% vs. 93%, respectively (p Conclusion: The combination of expression levels of BAALC, ERG and WT1 into a risk score identified a group of patients at high risk for relapse which could benefit from close monitoring resulting possibly in an early intervention when molecular relapse is detected. On the other hand, it identified a low risk group with very good outcome and no APL-related events after patients had achieved first CR. A molecular risk score focusing on relapse risk might be a promising approach to guide therapeutic decisions in the future. Disclosures No relevant conflicts of interest to declare.

Introduction: Early prediction of outcome using response-related predictive landmarks has become a major paradigm in the clinical management of chronic myeloid leukemia (CML). Several studies have shown the predictive impact of 10% BCR-ABLIS at 3 and 6 months for different tyrosine kinase inhibitors. The question, which landmark should define treatment failure and determine treatment intervention has been discussed vividly. However, an objective analysis of quality criteria for different early prognostic landmarks is lacking up to now. Here we compare sensitivity, specificity and the proportion of later disease progressions predicted by 3-month and 6-month landmarks in imatinib-treated patients of the CML-study IV.

Wilms’ tumor 1 gene (WT1) is known to be highly expressed in acute promyelocytic leukemia (APL) but information on its impact on prognosis is lacking. WT1 expression was analyzed in bone marrow samples of 79 patients with APL at initial diagnosis. Patients had a differing outcome according to their level of WT1 expression. In patients who achieved a complete remission (CR), low or high WT1 expression was significantly associated with inferior overall survival (OS) compared to intermediate WT1 expression (49% for WT1high vs. 63% for WT1low vs. 93% for WT1int; p = 0.008). Moreover, there were significant differences in relapse-free survival (RFS) between the three expression groups (42% for WT1high vs. 63% for WT1low vs. 83% for WT1int; p = 0.047). In multivariable analysis WT1 expression showed an independent prognostic impact on OS of responders to induction therapy. In conclusion, the level of WT1 expression can add prognostic information in APL risk stratification.

In acute promyelocytic leukemia (APL), relapse occurs in about 15 % of cases and is a major cause for death. Molecular markers identifying patients at high risk for relapse are not well established. High expression of the transcription factor Ets-related gene (ERG) is associated with inferior overall survival (OS) and disease-free survival in different types of hematologic malignancies. There are no data available about the impact of ERG expression in APL. ERG expression levels were analyzed in bone marrow samples of 86 APL patients at initial diagnosis. High ERG expression was significantly associated with an inferior OS in patients who had reached first complete remission. It was also significantly correlated with inferior relapse-free survival (RFS) and time to relapse (i.e., relapse-free interval, RFI). In multivariate analysis, high ERG expression had an independent negative impact on RFS and RFI. High ERG expression was significantly associated with inferior OS, RFS, and RFI. Moreover, in multivariate analysis, it maintained its value as an independent negative prognostic factor with regard to RFS and RFI. Therefore, ERG expression might serve as a molecular marker for risk stratification in APL and might identify patients who could benefit from intensified treatment regimens.

Introduction MDR1 gene expression has recently been reported to be associated with clinical outcome in imatinib-resistant patients with chronic myeloid leukemia (CML) on second-line nilotinib treatment (Agrawal et al., Leukemia 2014). High MDR1 expression was predictive for achieving deeper cytogenetic and molecular responses as well as duration of chronic phase. We thus prospectively evaluated the value of MDR1 expression analysis in the first-line situation within a large European, multicenter trial of CML patients under treatment with nilotinib.

Overexpression of transketolase-like gene 1 (TKTL1) on RNA and protein level has been linked to tumour progression, metastasis and unfavourable patient outcome in many solid tumours. Chronic myeloid leukaemia (CML) cells show metabolic characteristics resembling deviations observed in TKTL1 overexpressing solid tumour cells. We therefore sought to evaluate TKTL1 gene expression in different phases of CML.