Keywords acute lymphoblastic leukemia - high-dose cytarabine - MCP841 protocol - retrospective study - survival analysis
Introduction
Acute lymphoblastic leukemia (ALL) is one of the most common malignancies in children in India with relative proportion varying between 25 and 40%.[1 ] After the introduction of aggressive chemotherapy protocols like Berlin–Frankfurt–Münster (BFM), remarkable outcome has been seen in the developed countries resulting in cure rate of 80 to 90%.[2 ] The prognosis of ALL in India remains poor as the overall survival in ALL ranges from 45 to 81%.[3 ]
[4 ]
[5 ]
[6 ]
[7 ] This can be partly attributed to the logistic constraints to tackle side effects of aggressive protocols and nonadherence to treatment. Aggressive chemotherapy protocols, therapy stratification, and risk-adapted management represent major cornerstones in the treatment of childhood ALL.[8 ]
[9 ] The MCP841 protocol was developed for low- and middle-income countries as it can be delivered with minimal supportive care.[10 ]
Initially high-dose cytarabine (HDAC) at the dose of 2 g/m2 were given to those younger than 3 years who could not be given prophylactic cranial radiation. At the Tata Memorial Hospital, Mumbai, HDAC at the dose of 2 g/m2 was given to entire pediatric population, and the 4-year event-free survival (EFS) was reported to be 85.5%, which is at par with the EFS reported in cancer centers in developed countries. The incidence of posttherapy relapse was reported to be 15% in the MCP841 protocol in a study at the same center.[8 ]
Our primary objective was to study the EFS with HDAC as the backbone of the protocol.
The secondary objectives of the study were to determine the following:
Incidence of precursor B-cell ALL (B-ALL; standard, intermediate, and high risk) and T-cell ALL (T-ALL; standard and high risk) as per the criteria listed in [Table 1 ].
Incidence and cause of death in various risk groups of ALL.
Statistical correlation of risk stratification with mortality.
Table 1
Criteria for risk stratification
B-cell precursor ALL
Standard risk (precursor B-ALL SR)
• Children aged >1 and <10 y
• WBC count <50,000/mm3 at presentation
• Prednisolone good responder
• No testicular or bulky disease
• No high-risk cytogenetics
Intermediate risk (precursor B-ALL IR)
• Children ≥10 y or WBC count ≥50,000/mm3 at presentation
OR
• Testicular or bulky disease
AND
• Prednisolone good responder
• No high-risk cytogenetics
High risk (precursor B-ALL HR)
• High-risk cytogenetics t(9:22), translocations of chr.11, complex cytogenetics
• OR prednisolone poor responder
• OR central nervous system disease
T-cell ALL
Standard risk (T-ALL SR)
• WBC count <10,000/mm3 at presentation
• No bulky disease
• Prednisolone good responder
• Complete remission at the end of induction
• Not ETP-ALL
• No CNS disease
High-risk (T-ALL HR)
Any of the following:
• WBC ≥100,000/mm3 at presentation
• Bulky disease
• ETP phenotype
• T lymphoblastic lymphoma
• Prednisolone poor responder
• No complete remission after induction
• CNS disease
Abbreviations: ALL, acute lymphoblastic leukemia; CNS, central nervous system; ETP, early T-cell precursor ALL; HR, high risk; IR, intermediate risk; SR, standard risk; WBC, white blood cell.
Materials and Methods
In this retrospective observational study, data of 156 patients aged 1 to 19 years diagnosed with ALL from June 2009 to August 2013 at the Medical College and Hospital, Department of Medical Oncology and Department of Pediatrics, were analyzed. Immunophenotyping and conventional cytogenetic study were planned in all cases at diagnosis, but this was subject to logistic issues and nonavailability. The patients were treated according to the MCP841 protocol with HDAC (2 g/m2 every 12 hours for 2 days, repeated every 14 days for 3 cycles) for the entire population. The chemotherapy protocol followed is depicted in [Table 2 ]. Prophylactic cranial irradiation was given to children older than 3 years. Individuals were stratified into various risk groups as per the criteria mentioned in [Table 1 ]. Complete blood count (CBC) was performed thrice weekly and cerebrospinal fluid (CSF) examination was performed as per protocol to detect the central nervous system (CNS) relapse. Prednisone response was defined as reduction in a number of blood blasts per microliter after a 7-day prednisone prephase and one intrathecal dose of methotrexate on day 1. Prednisolone good response (PGR) is less than 1,000 blasts/μL, whereas prednisolone poor response (PPR) is ≥1,000 blasts/μL.[9 ] Remission death has been defined as death after remission and before completion of maintenance. Fluorescence in situ hybridization (FISH) cytogenetics and molecular genetics were avoided for risk stratification as they were not available during the study period across the population.
Table 2
Summarizing MCP841 chemotherapy protocol
Drugs
Induction (I1 )
Induction 2 (I2 )
I2 A
Repeat induction (RI1 )
Consolidation
Maintenance (6 cycles)
Prednisolone (40 mg/m2 )
D 1–28
▪
HDAC (2 g/m2 )
Repeat I1
D 1–7
▪
Vincristine (1.4 mg/m2 )
D 1, 8, 15, 22, 29
▪
D 1, 15
D 1
L-asparaginase (6,000 U/m2 )
D 2–20, alternate day
▪
▪
D 1, 3, 5, 7
Daunorubicin (30 mg/m2 )
D 8, 15, 29
▪
▪
D 1
Mercaptopurine (75 mg/m2 )
▪
Daily
D 1–7, 15–21
Start on day 15. Daily, 3 wk out of every 4 wk, for a total of 12 wk
Cyclophosphamide (750 mg/m2 )
▪
D 1, 15
D 1, 15
▪
Methotrexate (12 mg, IT)
D 1, 8, 15, 22
D 1, 8, 15, 22
▪
15 mg/m2 , orally, start on D 15, once a week, missing every 4th wk, for a total of 12 wk
Cranial irradiation (2,000 cGy)
▪
10 d
▪
▪
Cytarabine (70 mg/m2 )
▪
▪
D 1–3, D 15–17
▪
Abbreviations: D, day; HDAC, high-dose cytarabine; IT, intrathecal.
The black squares in the table denote that the drugs (mentioned in Rows) were not given in that particular phase of chemotherapy.
Supportive management and neutropenic care were instituted for all patients as per the institutional protocol. Investigations such as CBC, C-reactive protein, and blood culture were done in all suspected cases of sepsis and febrile neutropenia. Initial empirical antibiotics used were piperacillin-tazobactam and amikacin. Antibiotics were changed according to culture sensitivity reports. When neutropenic sepsis was associated with no identified organisms in blood culture, the choice of antibiotics was piperacillin-tazobactam + amikacin (first line), followed by meropenem + vancomycin (second line), and, finally, colistin and antifungals. Antifungals used for treatment were amphotericin B and voriconazole.
Primary outcome: To study the EFS with HDAC as the backbone of the protocol.
Secondary outcome: To estimate the incidence of risk-stratified ALL in pediatric patients and to determine the incidence and cause of death in various risk groups.
Inclusion Criteria
Patients aged 1 to 19 years newly diagnosed with ALL from June 2009 to August 2013 and treated according to the MCP841 protocol with HDAC (2 g/m2 ) were included in the study.
Exclusion Criteria
Treatment defaulters during any phase of treatment till re-intensification (RI1 ) and previously treated cases of ALL were excluded from the study.
Statistical Analysis
All statistical calculations were performed using the Statistical Package for the Social Sciences (SPSS) software for windows (IBM Corp., Armonk, NY, United States). The chi-squared test was performed to examine the relation between categorical variables and a value of p < 0.05 was considered significant. For survival analysis, Kaplan–Meir survival curves were plotted and log-rank (Mantel–Cox) test was performed; statistical significance (p < 0.05), chi-squared values, and mean survival with 95% confidence interval (CI) were calculated.
Ethics : Ethics committee approval was granted for this retrospective study by the Institutional Ethics Committee of Medical College, Kolkata (reference number: MC/KOL/IEC/NON-SPON/2158/07/2023 dated 19.07.2023). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Results
Between June 2009 and August 2013, 156 patients were included in this study after applying the exclusion criteria. Data were analyzed in February 2023. The mean age at presentation was 6.4 ± 0.3 years with a male preponderance of 60.8% (n = 95). In total, 109 patients (70%) were precursor B-ALL, of whom 76 (69.7%) were standard risk (pre-B-ALL SR), 22 (20.1%) were intermediate risk (pre-B-ALL IR), and 11 (10%) were high risk (pre-B-ALL HR). In all, 47 (30%) patients had T-ALL, of whom 35 (74.4%) were standard risk (T-ALL SR) and 12 (25.5%) were high risk (T-ALL HR).
Fever was the most common presenting symptom (79.5%), followed by lymphadenopathy (69.8%) and hepatosplenomegaly (52%). Hyperleukocytosis was present in 24 (15%) patients at diagnosis. Approximately 80% were treated in the general pediatric ward and 20% in the oncology ward.
PGR on day 8 was seen in 98 (62.8%) patients. In total, 140 (89.7%) patients achieved remission (<5% blast on bone marrow examination, i.e., M1) at the end of induction and 16 (10.3%) patients died during the induction phase. Twelve of 16 (75%) children who faced induction mortality had a median gap of 2.5 months or more from symptom onset and initiation of treatment. Thirteen of 16 (∼81.25%) children who faced induction mortality were suffering from moderate acute malnutrition and 2 (12.5%) were suffering from severe acute malnutrition. Blood culture was positive in approximately 31% (n = 49) patients during the course of treatment. The most common organisms isolated in bacterial sepsis were Klebsiella pneumoniae , Pseudomonas sp., Staphylococcus aureus , and enterococci.
[Tables 3 ] and [4 ] depict the frequencies and causes of death during induction, remission death, and EFS according to the risk stratification. The causes of induction death were infection in 10 (62.5%) patients, hemorrhage in 4 (25%) patients, and neurological cause, that is, cortical venous thrombosis in 2 (12.5%) patients. Among infection, bacterial neutropenic sepsis was the most common (n = 5, 50%), followed by fungal pneumonia (n = 3, 30%), systemic candidiasis (n = 1, 10%), and human immunodeficiency virus (HIV) infection (n = 1, 10%). Among those who attained remission (89.7%, n = 140), relapse occurred in 26% (n = 27) precursor B-ALL and 28% (n = 10) T-ALL patients. Forty-eight patients (30.7%) died during the postinduction period and the causes of mortality included progressive disease due to relapse in 37 (77%) patients and infection in 11 (22.9%) patients. The commonest cause of overall mortality was progressive disease due to relapse, occurring mostly in the consolidation and maintenance phase. Bone marrow was the commonest site of relapse and observed in 35 (94.6%) patients, followed by testicular relapse in 2 (5%) patients. Bone marrow and testicular relapse occurred at a median gap of 24 and 42 months, respectively, after initiation of treatment. No cases of CNS relapse were seen in our study.
Table 3
Details of mortality and event-free survival according to risk-stratified groups
Type of malignancy
Risk stratification
No. of patients (N = 156)
No. of deaths during induction (N = 16)
Remission death (N = 48)
Event-free survival in each group
n
%
n
%
n
%
n
%
Pre B-ALL
Pre B-ALL SR
76
48.7
1
6.2
21
43.7
54
71
Pre B-ALL IR
22
14.1
1
6.2
10
20.8
11
50
Pre B-ALL HR
11
7.0
3
18.7
5
10.4
3
27
T-ALL
T-ALL SR
35
22.4
1
6.2
11
22.9
23
65
T-ALL HR
12
7.6
10
62.5
1
2.08
1
8
Abbreviations: B-ALL; B-cell acute lymphoblastic leukemia; HIV, human immunodeficiency virus; HR, high risk; IR, intermediate risk; Pre, precursor; SR, standard risk; T-ALL, T-cell acute lymphoblastic leukemia.
Table 4
Details of mortality during induction according to risk-stratified groups
Risk stratification
No. of patients (n )
Cause of induction death
No. of deaths during induction (N = 16)
n
%
Pre B-ALL SR
76
Cortical venous thrombosis
1
6.2
Pre B-ALL IR
22
Neutropenic sepsis
1
6.2
Pre B-ALL HR
11
Fungal pneumonia
2
12.5
Neutropenic sepsis
1
6.2
T-ALL SR
35
Neutropenic sepsis
1
6.2
T-ALL HR
12
Hemorrhage
4
25
Neutropenic sepsis
2
12.5
Systemic candidiasis
1
6.2
Fungal pneumonia
1
6.2
HIV
1
6.2
Cortical venous thrombosis
1
6.2
Abbreviations: B-ALL, B-cell acute lymphoblastic leukemia; HIV, human immunodeficiency virus; HR, high risk; IR, intermediate risk; Pre, precursor; SR, standard risk; T-ALL, T-cell acute lymphoblastic leukemia.
The chi-squared test of independence was performed to examine the relation between risk groups and the incidence of induction mortality. The relation between these variables were significant (χ
2 = 82.54, p <0.0001). However, the chi-squared test of independence between risk groups and incidence of remission death and overall survival was not significant (χ
2 = 6.07, p = 0.19). The EFS at 168 months was 59%. Relapse-free survival by Kaplan–Meir analysis ([Fig. 1 ]) was 62.4% for precursor B-cell ALL and 51.1% for T-ALL (log-rank, χ
2 = 1.931, p = 0.165). The mean survival for B and T lineages was 111.19 months (95% CI: 97.86–124.51) and 94.36 months (95% CI: 73.04–115.68), respectively.
Fig. 1 A Kaplan–Meier survival plot showing relapse-free survival probability for T-cell acute lymphoblastic leukemia (ALL) and B-cell ALL. Cumulative survival (Y axis) has been plotted against time (in months) since diagnosis (X axis).
Discussion and Conclusion
Discussion and Conclusion
The 5-year survival rate for ALL in the western world is approximately 90% in children younger than 15 years.[11 ] Compared to the developed world, the biology of ALL appears different in India, with a higher proportion of T-ALL (20–50% as compared to 10–20% in the developed world), hypodiploidy and translocations t (1;19), t (9;22), and t (4;11). All of these factors contribute to a poorer prognosis of leukemia.[1 ]
The incidence of induction mortality was higher in the T-ALL HR group; however, the statistical difference in EFS was not significant between pre-B-ALL SR and T-ALL SR groups treated by the MCP841 protocol. The most common cause of induction death was neutropenic sepsis. Factors such as malnutrition contributed to the increased risk of mortality during the induction period. In the randomized intercontinental trial by Starý et al on intensive chemotherapy for childhood ALL by BFM 2002, PGR was reported in 90.2%,[12 ] while in a study on outcome of ALL with the ALL-BFM-95 protocol in Nepal by Sharma Poudyal et al, PGR was reported in 71.8% patients.[13 ] In our study, PGR was reported in 62.8% patients. Out of a total of 64 deaths, most occurred due to relapse in the postinduction period (n = 37 [57%] of overall mortality). Bone marrow is the most frequent site of relapse and no CNS relapse was seen. Advani et al obtained similar results for bone marrow relapse, and five patients had a combined bone marrow and CNS relapse.[5 ] All cases of relapse were advised bone marrow transplant and were referred to institutions with a bone marrow transplant facility. As per the institutional protocol, the cases of relapse were further treated with the St. Jude Protocol and the CCG112 protocol for testicular relapse, but there was no reported survival in cases of relapse in our study.
EFS in our study was 59% at 168 months, which is comparable to the 49% EFS at the end of 5 years reported by Advani et al.[5 ] In a study by Kapoor et al, relapse-free survival at 5 years was 62% for B-ALL and 28% T-ALL; overall, 53.2% of the patients were in remission at the end of 5 years of starting of treatment.[10 ] According to the results of randomized intercontinental trial by Starý et al on intensive chemotherapy for childhood ALL by BFM 2002, the 5-year EFS was overall 74% (75% in B-cell precursor and 69% in T cell), 81% in the SR group, 75% in the IR group, and 55% in the HR group.[12 ] According to a study on outcome of ALL with the ALL-BFM-95 protocol in Nepal by Sharma Poudyal et al in 2023, the 3-year overall survival and relapse-free survival were 89.4 and 87.3%, respectively. The study undertaken by Sharma Poudyal et al also mentions that the 5-year EFS was 28% in childhood ALL between 1998 and 2012.[13 ] The higher survival of childhood ALL in recent years, as compared to our study, can be attributed to improving oncological resources over the years, such as enhanced infrastructure and supportive care, awareness among patients, early diagnosis, and specialized training of health care workers.
In spite of its drawbacks, MCP841 using HDAC as a backbone of the protocol is an effective tool for treatment of children suffering from ALL and it has similar survival outcomes in precursor B-ALL and T-ALL. With improving oncological resources, the overall survival has improved in the more recent studies. However, MCP841 remains an important tool in a background of resource-constraint settings and high abandonment. Achieving 50% survival in children with ALL is a challenge in India, and we have reached a comparable survival outcome in par with similar centers in developing countries with the MCP841 protocol. Combating treatment in malnourished children and bridging infections are the major hurdles to improving outcome in developing countries.
Drawbacks
This study is based on a single-center experience, and there is a limitation of available data as it is a retrospective study. Immunophenotyping and cytogenetic reports of all patients could not be procured due to logistic issues and nonavailability of facilities during the time of patient treatment almost two decades ago. Hence, it was not possible to perform a detailed analysis of the correlation between the outcomes based on detailed hematological and cytogenetic reports.
