Childhood CML in India: b2a2 transcript is more common than b3a2

The Biology of Chronic Myelogenous Leukemia in Childhood and Young Adolescents: An Indian Perspective

Objective: The purpose of this study was to determine the clinical, biological, and molecular characteristics at diagnosis in children and adolescents with chronic myelogenous leukemia (CML) in the Indian scenario at our tertiary patient care center. Subjects and Methods: We evaluated 51 children and adolescents with CML registered at our clinic, from January 2007 to December 2015. The mean and median of various parameters were calculated using a Microsoft excel sheet and SPSS software version 16. Results: The median age of presentation in children was 16 years; 92.2% of them were older than 10 years, with a higher prevalence in boys than girls (gender ratio 2.6:1). The symptoms at presentation were fatigue, fever, awareness of mass due to splenomegaly, and bleeding manifestations. One patient presented with Bell's palsy. Markedly raised leukocyte counts were present in 29.4% patients (median white blood cell count >400 × 109/L). Most of the patients presented in the chronic phase of the disease, four each were in accelerated phase and blast crisis, respectively. Majority of patients were categorized as intermediate risk as per Sokal and Hansford score. About 60.7% of these pediatric patients fell in low-risk category as per European Treatment and Outcome Study score at baseline. A predominance of transcript P210-b3a2 (68%) was observed in the children who were studied for the type of chimeric BCR-ABL mRNA. Conclusions: This is one of the most recent reported series of CML in children and adolescents from India highlighting the difference in presentation from adults; mainly hepatomegaly, bleeding manifestations, and higher leukocyte count. Presence of b3a3 transcript of p210 breakpoint of BCR-ABL was more common in children (68%) than b2a2 transcript (32%) when compared to adults as recently described in a study from India, which may explain the differences at presentation.

Comparative Study of Clinico-hematological Features, Molecular Spectrum and Response to Imatinib in Chronic Myelogenous Leukemia Patients: Pediatric and Adolescent Versus Adults

Chronic myelogenous leukemia (CML) is a rare disease in children, accounting for approximately 3% of leukemias in children and adolescents, with an annual incidence of 1 case per million children in western countries. This study was conducted, at PGIMER, Chandigarh. Ninety eight patients, 48 in children and adolescents group, and 50 in adult group were included in the study. Their hematological profiles along with the bone marrow findings were analyzed. The diagnosis of CML was confirmed by cytogenetics and/or molecular analysis. The complete hematological response (CHR) was analyzed at 3 months and cytogentic response (CgR) at 12 months after starting imatinib therapy. Compared to adults, pediatric and adolescent patients were more symptomatic at presentation (93.5 vs. 75%). Among symptomatic patients, massive splenomegaly (>10 cm), higher total leucocyte and platelet counts were seen more frequently in pediatric patients. The most common transcript in both groups was e14a2. The distribution of pediatric and adolescent cases in Sokal, Hasford and EUTOS score, showed only statistically significant difference for low risk Sokal group, which had more patients in pediatric group. Compared to adults, pediatric and adolescent patients had similar CHR rate (91.3 vs. 92%), but showed lesser major CgR rate (90.9 vs. 95.5%) however, this was not statistically significant.

Pediatric chronic myeloid leukemia is a unique disease that requires a different approach

Chronic myelogenous leukemia (CML) in children is relatively rare. Because of a lack of robust clinical study evidence, management of CML in children is not standardized and often follows guidelines developed for adults. Children and young adults tend to have a more aggressive clinical presentation than older adults, and prognostic scores for adult CML do not apply to children. CML in children has been considered to have the same biology as in adults, but recent data indicate that some genetic differences exist in pediatric and adult CML. Because children with CML may receive tyrosine kinase inhibitor (TKI) therapy for many decades, and are exposed to TKIs during a period of active growth, morbidities in children with CML may be distinct from those in adults and require careful monitoring. Aggressive strategies, such as eradication of CML stem cells with limited duration and intensive regimens of chemotherapy and TKIs, may be more advantageous in children as a way to avoid lifelong exposure to TKIs and their associated adverse effects. Blood and marrow transplantation in pediatric CML is currently indicated only for recurrent progressive disease, and the acute and long-term toxicities of this option should be carefully evaluated against the complications associated with lifelong use of TKIs.

Differences among young adults, adults and elderly chronic myeloid leukemia patients

BACKGROUND

The incidence of chronic myeloid leukemia (CML) increases with age, but it is unclear how the characteristics of the disease vary with age. In children, where CML is very rare, it presents with more aggressive features, including huge splenomegaly, higher cell count and higher blast cell percentage.

PATIENTS AND METHODS

To investigate if after childhood the disease maintains or loses these characteristics of aggressiveness, we analyzed 2784 adult patients, at least 18 years old, registered by GIMEMA CML WP over a 40-year period.

RESULTS

Young adults (YAs: 18-29 years old) significantly differed from adults (30-59 years old) and elderly patients (at least 60 years old) particularly for the frequency of splenomegaly (71%, 63% and 55%, P < 0.001), and the greater spleen size (median value: 4.5, 3.0 and 1.0 cm, P < 0.001). According to the EUTOS score, that is age-independent, high-risk patients were more frequent among YAs, than among adult and elderly patients (18%, 9% and 6%, P < 0.001). In tyrosine kinase inhibitors-treated patients, the rates of complete cytogenetic and major molecular response were lower in YAs, and the probability of transformation was higher (16%, 5% and 7%, P = 0.011).

CONCLUSIONS

The characteristics of CML or the host response to leukemia differ with age. The knowledge of these differences and of their causes may help to refine the treatment and to improve the outcome.

CLINICAL TRIAL NUMBERS

NCT00510926, NCT00514488, NCT00769327, NCT00481052.

CML in pregnancy and childhood

With the improved survivals offered by the tyrosine kinase inhibitors has come the necessity to address issues relating to quality of life and one such area is that of fertility and parenting. Animal data suggest that imatinib at standard dosages is unlikely to impair fertility in either adult males or females but human data remain limited. Children born to men who are actively taking imatinib at the time of conception appear healthy and current advice is not to discontinue treatment. In contrast the data relating to children born to women exposed to imatinib during pregnancy are less encouraging. Although numbers are small there has been a disturbing cluster of rare congenital malformations such that imatinib cannot be safely recommended, particularly during the period of organogenesis. The appropriate management of children with CML has also been radically changed by the advent of imatinib. The features of the disease at presentation, the natural history and the response to therapy seem to be identical in children to that seen in adults. Now that imatinib has been in clinical use for almost ten years without severe long-term side effects, most physicians are now comfortable advising a trial of imatinib prior to consideration of transplant. Data relating to the efficacy and safety of second generation tyrosine kinase inhibitors in childhood is entirely absent and transplant remains the first choice for patients failing imatinib and perhaps also for young patients with sub-optimal responses.

Correlation of BCR/ABL transcript variants with patients' characteristics in childhood chronic myeloid leukaemia

BACKGROUND AND OBJECTIVE

The characteristic chromosomal translocation t(9;22)(q34;q11) in chronic myeloid leukaemia (CML) mainly results in the two different BCR/ABL fusion transcripts b2a2 or b3a2. Both transcript variants can occur simultaneously due to alternative splicing of the b3a2 transcript. Conflicting results have been reported on the influence of the transcripts on haematological findings at diagnosis and the course of the disease in adults while data concerning these topics on childhood CML are still missing. This paper reports on a correlation of BCR/ABL transcript variants with patients' characteristics in childhood CML.

DESIGN AND METHODS

Transcript types were determined in 146 paediatric patients with CML enrolled in trial CML-paed-I. Fifty-five patients (38%) expressed b2a2, 53 patients (36%) b3a2 and 38 patients (26%) both transcripts, respectively. These findings were correlated with patients' characteristics (sex, age, WBC, Hb, platelet count, hepatosplenomegaly, etc.) assessed at diagnosis.

RESULTS

While the co-expression of both transcripts was evenly distributed among genders [b2a2 + b3a2: 22 females (28%), 16 males (24%)] a highly significant difference (P = 0.007) was found concerning the expression of the b2a2 transcript [34 male (51%) vs. 21 female (27%)] and vice versa of the b3a2 transcript [17 male (25%) vs. 36 female (45%)]. High platelet counts and the combination of high platelet counts in conjunction with pronounced leukocytosis were observed more often in patients expressing the b3a2 transcript.

CONCLUSIONS

These findings demonstrate that in children like in adults specific BCR/ABL transcript types present at diagnosis are associated with distinct haematological alterations (e.g. a high platelet count with the transcript b3a2). However, the sex-dependent skewed distribution of the BCR/ABL transcript types observed so far in this paediatric cohort only deserves further investigation.