Absolute lymphocyte counts refine minimal residual disease-based risk stratification in childhood acute lymphoblastic leukemia

IL-10 and TNFα are associated with decreased survival in low-risk pediatric acute myeloid leukemia; a children's oncology group report

Pediatric acute myeloid leukemia (AML) is a devastating disease with a high risk of relapse. Current risk classification designates patients as high or low risk (LR) based on molecular features and therapy response. However, 30% of LR patients still suffer relapse, indicating a need for improvement in risk stratification. Cytokine levels, such as IL-6 and IL-10, have been shown to be prognostic in adult AML but have not been well studied in children. Previously, we reported elevated IL-6 levels in pediatric AML bone marrow to be associated with inferior prognosis. Here, we expanded our investigation to assess cytokine levels in diagnostic peripheral blood plasma (PBP) of pediatric AML patients and determined correlation with outcome. Diagnostic PBP was obtained from 80 patients with LR AML enrolled on the Children's Oncology Group AAML1031 study and normal PBP from 11 controls. Cytokine levels were measured and correlation with clinical outcome was assessed. IL-6, TNFα, MIP-3a, and IL-1β were significantly higher in AML patients versus controls when corrected by the Bonferroni method. Furthermore, elevated TNFα and IL-10 were significantly associated with inferior outcomes. Our data demonstrate that in diagnostic PBP of LR pediatric AML patients, certain cytokine levels are elevated as compared to healthy controls and that elevated TNFα and IL-10 are associated with inferior outcomes, supporting the idea that an abnormal inflammatory state may predict poor outcomes. Studies are needed to determine the mechanisms by which these cytokines impact survival, and to further evaluate their use as prognostic biomarkers in pediatric AML.

Combined use of peripheral blood blast count and platelet count during and after induction therapy to predict prognosis in children with acute lymphoblastic leukemia

Several studies have reported an association between the rapidity of reduction in peripheral blood blast count or recovery of normal hematopoiesis and treatment outcome during therapy in children with acute lymphoblastic leukemia (ALL). However, little is known about the impact of both of these aspects on prognosis in pediatric ALL. Accordingly, the purpose of this study was to evaluate whether the combined use of blood blast count and platelet count could predict event-free survival (EFS) and overall survival (OS) when minimal residual disease (MRD) detection was not available.A total of 419 patients aged 0 to 14 years diagnosed and treated for ALL between 2011 and 2015 were enrolled.Patients with a blast count ≥0.1 × 109/L on day 8 exhibited significantly lower survival rates than that in those with blast counts <0.1 × 109/L. The EFS and OS in patients with platelet count ≥100 × 109/L on day 33 were significantly higher than those with platelet counts <100 × 109/L. In univariate and multivariate analyses, patients with low blast count on day 8 and high platelet count on day 33 were significantly associated with better EFS and OS. The combination of blast cell count on day 8 and platelet count on day 33 demonstrated a strong association with MRD-based risk stratification.Complete blood count is an inexpensive, easy to perform, and reliable measurement in children with ALL. The combination of blast count and platelet count during and after induction chemotherapy was a significant and independent prognostic factor for treatment outcome in pediatric ALL.

Differential Depletion of Bone Marrow Resident B-ALL after Systemic Administration of Endosomal TLR Agonists

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. While frontline chemotherapy regimens are generally very effective, the prognosis for patients whose leukemia returns remains poor. The presence of measurable residual disease (MRD) in bone marrow at the completion of induction therapy is the strongest predictor of relapse, suggesting that strategies to eliminate the residual leukemic blasts from this niche could reduce the incidence of recurrence. We have previously reported that toll-like receptor (TLR) agonists achieve durable T cell-mediated protection in transplantable cell line-based models of B cell precursor leukemia (B-ALL). However, the successful application of TLR agonist therapy in an MRD setting would require the induction of anti-leukemic immune activity specifically in the bone marrow, a site of the chemotherapy-resistant leukemic blasts. In this study, we compare the organ-specific depletion of human and mouse primary B-ALL cells after systemic administration of endosomal TLR agonists. Despite comparable splenic responses, only the TLR9 agonist induced strong innate immune responses in the bone marrow and achieved a near-complete elimination of B-ALL cells. This pattern of response was associated with the most significantly prolonged disease-free survival. Overall, our findings identify innate immune activity in the bone marrow that is associated with durable TLR-induced protection against B-ALL outgrowth.

Time course of peripheral blood count recovery during induction chemotherapy for childhood acute lymphoblastic leukemia

Introduction: Children with newly diagnosed acute lymphoblastic leukemia (ALL) present with low peripheral blood counts caused by bone marrow replacement. The recovery of counts during induction chemotherapy is not well described. Material and methods: Records for 63 children with ALL were reviewed. Peripheral hematology blood counts during five weeks of induction chemotherapy were extracted, and the time to partial recovery with safe counts and complete recovery with normal counts in the three cell lines determined. The number of red cell and platelet transfusions, the number of febrile episodes, and the number of days on intravenous antibiotics were counted. Results: Platelet recovery occurred early: median time to achieving counts >50/nL 14 days, to counts >100/nL 16 days. Neutrophil recovery was relatively slow: median time to counts >0.5/nL 18 days, to counts >1.0/nL 26 days. The time to partial recovery was shorter in high risk than in lower-risk treatment groups. Partial platelet recovery by day 15 indicated early recovery and lower morbidity. Complete platelet recovery day 15 was significantly associated with residual disease <0.1% after four weeks. Lymphocyte counts showed a marked decrease in first two weeks followed by a rise in the next three weeks; a count <0.35/nL on day 15 was associated with poor response. Conclusion: After starting chemotherapy for ALL, platelet recovery can be expected after two to three weeks while neutrophil recovery lasts three to five weeks. Platelet and lymphocyte counts after two weeks treatment may give an indication of residual disease after four weeks.

Association of absolute lymphocyte count and peripheral blood lymphocyte subsets percentage with minimal residual disease at the end of induction in pediatric B cell acute lymphoblastic leukemia

Absolute lymphocyte count (ALC) has been associated with overall survival (OS) and event-free survival, but we do not know if ALC is associated with minimal residual disease (MRD) at the end of induction (EOI) and whether it can be used as surrogate marker in resource limited settings. Immunological differences between MRD-positive and MRD-negative B ALL patients at the EOI are not known at present. This prospective study evaluated the association of ALC and peripheral blood lymphocyte subset percentage at the EOI with MRD. ALC was done at baseline, day 8, and day 15 and at EOI. Assessment for MRD and peripheral blood lymphocyte subset was done at EOI. In 2-year study duration, 197 B cell acute lymphoblastic leukemia (ALL) patients were recruited out of which 150 were analyzed. Peripheral lymphocyte subset percentage was available for 58 patients. We found that ALC at baseline, day 8, day 15, and EOI was not associated with MRD. Day 8 ALC was significantly higher in poor steroid responders (day 8 blasts > 1 × 10⁹ cells/l) (p < 0.0001). At the EOI, CD4^-CD8⁺ cell percentage in peripheral blood were significantly higher in MRD-positive patients than MRD-negative patients (p = 0.01). Our study suggests that ALC at any point is not a surrogate marker for MRD. Immunologically MRD-positive and MRD-negative patients differ in CD4^-CD8⁺ cells. The role of CD8⁺T and TCRαβCD3⁺T cells in eliminating residual leukemic cells need to be studied further by functional assays.

Absolute lymphocyte counts at end of induction correlate with distinct immune cell compartments in pediatric B cell precursor acute lymphoblastic leukemia

Several retrospective studies in children with B cell precursor (BCP) acute lymphoblastic leukemia (ALL) provided clinical evidence that higher absolute lymphocyte counts (ALC) early into treatment significantly correlated with improved relapse-free and overall survival. It still remains unknown, however, whether the predictive role of higher ALCs reflects general bone marrow recovery or a more specific attribute of immune function. To investigate this question, we implemented a prospective observational cohort study in 20 children with BCP ALL on day 29 (D29) of induction chemotherapy and immunophenotyped their lymphoid (T, B and natural killer cells) and myeloid (neutrophils, monocytes, dendritic cells) compartments. In a first evaluation of a cohort treated with Children's Oncology Group-based induction chemotherapy, the immune cell compartments were differentially depleted at D29. Neither gender, risk status, minimal residual disease, nor bone marrow recovery markers correlated with D29 ALC. In contrast, both CD3+ T cell and dendritic cell compartments, which did not correlate with age, significantly correlated with D29 ALC (p < 0.0001). In addition, subset complexity of cellular immune compartments was preserved at D29. This study reveals that D29 ALC significantly correlates with distinct immune cell compartments but not with bone marrow recovery markers, suggesting that higher D29 ALCs may contribute to leukemia control by inducing specific host immune activity.

Absolute Lymphocyte Count (ALC) after Induction Treatment Predicts Survival of Pediatric Patients with Acute Lymphoblastic Leukemia

Absolute Lymphocyte Count (ALC) has been recently established as a prognostic factor of survival in pediatric Acute Lymphoblastic Leukemia (ALL). A retrospective analysis of 132 patients treated according the BFM - ALLIC 2002 protocol was performed in a single institution. A possible association between ALC values and Overall Survival (OS) or Event-Free Survival (EFS) was evaluated at multiple time points during induction chemotherapy. ALC higher than 350 cells/μL measured on the 33th day of induction was associated with better Overall- and Event-Free Survival in both Kaplan-Meier (OS 88.6% vs. 40%; p < 0.001 / EFS 81.6% vs. 30%; p < 0.001) and Cox regression (OS HR 8.77 (3.31-23.28); p < 0.001) and EFS HR 6.61 (2.79-15.63); p < 0.001) analyses. There was no association between survival and measured ALC values from earlier time points (day of diagnosis, days 8 and 15) of induction therapy. Patients with low ALC values tend to have higher risk (MR or HR groups) and a higher age at diagnosis (>10 years). With help of day 33 ALC values of 350 cells/μL cutoff it was possible to refine day 33 flow cytometry (FC) Minimal Residual Disease (MRD) results within the negative cohort: higher ALC values were significantly associated with better survival. ALC on day 33 (350 cells/μL) remained prognostic for OS and EFS in multivariate analysis after adjusting it for age, cytogenetics, immunophenotype and FC MRD of induction day 33. According to these findings ALC on day 33 of induction is a strong predictor of survival in pediatric ALL.

Absolute Lymphocyte Count Recovery Independently Predicts Outcome in Childhood Acute Lymphoblastic Leukemia: Experience From a Tertiary Care Cancer Center of a Developing Country

BACKGROUND

Accurate risk stratification is essential for successful treatment outcome in childhood acute lymphoblastic leukemia. Early recovery of absolute lymphocyte count (ALC) during induction therapy is emerging as a reliable favorable prognostic indicator that may hold its relevance in resource-constraint settings.

MATERIALS AND METHODS

This is a retrospective chart review of medical records of 212 patients of acute lymphoblastic leukemia, aged less than 18 years, treated between January 1996 and December 2009. Time to lymphocyte recovery was analyzed with respect to various prognostic factors and survival and Martingale residuals were used to define ALC cut-offs.

RESULTS

High-risk disease characteristics including older age (10 y and older), National Cancer Institute high risk, and central nervous system disease at diagnosis were associated with delayed lymphocyte recovery. The 5-year event-free, relapse-free, and overall survival of patients with day 15 ALC of ≥ 500 cells/µL and day 29 ALC of ≥ 1000 cells/µL was 81.7% ± 4%, 86.4% ± 2.8%, 91.0% ± 3%, respectively, compared with those with delayed recovery (16.6% ± 5.6%, 19.3% ± 6.4%, 32.8% ± 7.2%, P < 0.001). In multivariate analysis both these ALC cut-offs retained their significance as prognostic variables of survival.

CONCLUSION

Our analysis revealed ALC to be an important independent predictor of treatment outcome and may provide key prognostic information in settings where minimal residual disease-based risk stratification is not feasible.

Generation of tumor antigen-specific T cell lines from pediatric patients with acute lymphoblastic leukemia--implications for immunotherapy

PURPOSE

Although modern cure rates for childhood acute lymphoblastic leukemia (ALL) exceed 80%, the outlook remains poor in patients with high-risk disease and those who relapse, especially when allogeneic hematopoietic stem cell transplantation is not feasible. Strategies to improve outcome and prevent relapse are therefore required. Immunotherapy with antigen-specific T cells can have antileukemic activity without the toxicities seen with intensive chemotherapy, and therefore represents an attractive strategy to improve the outcome of high-risk patients with ALL. We explored the feasibility of generating tumor antigen-specific T cells ex vivo from the peripheral blood of 50 patients with ALL [26 National Cancer Institute (NCI) high-risk and 24 standard-risk] receiving maintenance therapy.

EXPERIMENTAL DESIGN

Peripheral blood mononuclear cells were stimulated with autologous dendritic cells pulsed with complete peptide libraries of WT1, Survivin, MAGE-A3, and PRAME, antigens frequently expressed on ALL blasts.

RESULTS

T-cell lines were successfully expanded from all patients, despite low lymphocyte counts and irrespective of NCI risk group. Antigen-specificity was observed in more than 50% of patients after the initial stimulation and increased to more than 90% after three stimulations as assessed in IFN-γ-enzyme-linked immunospot (ELISpot) and (51)Cr-release assays. Moreover, tumor-specific responses were observed by reduction of autologous leukemia blasts in short- and long-term coculture experiments.

CONCLUSION

This study supports the use of immunotherapy with adoptively transferred autologous tumor antigen-specific T cells to prevent relapse and improve the prognosis of patients with high-risk ALL.

Prognostic impact of absolute lymphocyte counts at the end of remission induction in childhood acute lymphoblastic leukemia

BACKGROUND

Absolute lymphocyte counts (ALC) during treatment have been associated with outcome in children and adults with hematologic malignancies. However, the impact of ALC relative to that of other prognostic factors on the outcome of children with acute lymphoblastic leukemia (ALL) treated in recent trials is unknown.

METHODS

Outcomes of 399 patients aged ≤18 years with newly diagnosed ALL who were enrolled in the Total Therapy XV study at St. Jude Children's Research Hospital were analyzed according to ALC at the end of remission induction therapy.

RESULTS

An ALC ≥500 cells/μL was significantly more prevalent among patients with B-lineage ALL, in those with favorable presenting features, and in those who achieved negative minimal residual disease (MRD) status on day 43 of treatment. Both overall survival (OS) and event-free survival (EFS) were superior among patients with higher ALC, but only the association with OS was statistically significant in a univariate analysis. In multivariable analyses, ALC was not a significant predictor of outcome after controlling for age, leukocyte count, lineage, risk group, and MRD status at the end of induction (P > .1 for all comparisons). However, among MRD-negative patients, those with low ALC had a 5-year OS rate of 84.2% ± 8.9% versus 97.3% ± 1.0% for patients with higher ALC (P = .036).

CONCLUSIONS

ALC at the end of induction is related to favorable presenting features and good initial treatment response but does not independently predict outcome in the context of contemporary, MRD-guided therapy.

Absolute lymphocyte count is associated with minimal residual disease level in childhood B-cell precursor acute lymphoblastic leukemia

The prognostic value of absolute lymphocyte count (ALC) has been a recent matter of debate in childhood acute lymphoblastic leukemia (ALL). In the current study, ALCs at the time of diagnosis (ALC-0), after 7 days of initial therapy (ALC-8) and at interim of the induction therapy (ALC-22) were examined in Chinese children with B-cell precursor (BCP) ALL and correlated with the level of minimal residual disease (MRD) at day 22 of induction therapy. Medical and laboratory records of 140 patients diagnosed with childhood BCP ALL were retrieved and analyzed. ALC-22 is significantly correlated with MRD level at day 22 of therapy and can be a good prognostic factor for childhood BCP-ALL. Furthermore, lymphocyte count at initial diagnosis is correlated with MRD level at day 22 in childhood BCP-ALL with the immnunophenotype of CD19(pos)/CD10(pos)/CD34(pos)/CD45(neg) and role as a new prognostic factor was determined.