Successful treatment with ponatinib for central nervous system relapse of Philadelphia chromosome‐positive B‐cell acute lymphoblastic leukaemia

Diagnostic significance of cerebrospinal fluid flow cytometry in Chinese children with B lineage acute lymphoblastic leukemia

BACKGROUND

Central nervous system leukemia (CNSL) is one of the major causes of the poor prognosis of childhood leukemia. We aimed to compare the sensitivity of cytomorphology (CM) and flow cytometry (FCM) in diagnosing CNSL, emphasizing the importance of FCM in the diagnosis process.

METHODS

One-hundred-sixty-five children with newly diagnosed B-cell Acute Lymphoblastic Leukemia (B-cell ALL) were included in this study. Cerebrospinal fluid (CSF) samples were taken for routine CSF analysis, CM analysis, and FCM examination. Computed tomography scans and/or magnetic resonance imaging were performed at diagnosis. Patients with CNS2, CNS3, and traumatic lumbar puncture (TLP) at diagnosis received two additional courses of triple intrathecal injections during induction treatment. We compared the sensitivity of FCM and CM in the diagnosis of children with CNSL.

RESULTS

One hundred and twenty-eight (77.58%) CSF samples were negative by either CM or FCM (CM-/FCM-), four (2.42%) were positive by both CM and FCM (CM+/FCM+), and thirty-three (20%) displayed a single positive finding by FCM (CM-/FCM+) (p = 0.044). By adding two intrathecal injections in the induction treatment, ten children with TLP+ had no CNS relapse, like those with TLP-. However, compared to CNS1 and TLP, the event-free survival (EFS) did not significantly improve in patients with CNS2 and CNS3. Moreover, CNSL status was associated with worse 3-year EFS (p < 0.05).

CONCLUSIONS

We have validated that FCM is more accurate in stratifying the status of the CNS compared to CM analysis. However, to improve the EFS rate of childhood leukemia, it is necessary to combine CM examination, FCM, and cranial imaging for the early diagnosis of CNSL.

Efficacy and safety of ponatinib for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia: a case series from a single institute

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) is an aggressive leukemia that occurs in 20-40% of adult patients. Ph + ALL is caused by the Philadelphia chromosome (Ph), which consists of a t(9;22)(q34;q11) reciprocal translocation leading to the formation of a BCR-ABL1 fusion gene. The disease is treated with targeted therapy comprising ABL1 tyrosine kinase inhibitors (TKIs). Ponatinib is a third generation TKI that demonstrates higher binding affinity for ABL1 than first/second generation TKIs. Although intensive combined immunotherapy with ponatinib greatly improves the prognosis of Ph + ALL, the safety and efficacy profiles of ponatinib in Japanese patients are unclear. This retrospective study investigated five cases of Ph + ALL at a single institute to evaluate safety and efficacy profiles. Three patients achieved a deep molecular response (DMR) following combined intensive treatment with ponatinib as induction chemotherapy. Four patients received consolidative allogenic stem cell transplantation (allo-SCT) during their first complete response. Three of the four experienced early relapse within 100 days; they subsequently received ponatinib, and one of the three achieved a DMR. No patient experienced severe cardiovascular events. This case series suggests that ponatinib at a concentration of least 30 mg exhibits anti-leukemia effects in Japanese patients with Ph + ALL.

Monitoring Ponatinib in a Child with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Ponatinib is a third-generation tyrosine kinase inhibitor (TKI) reported to show a higher efficacy for adult Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) than other TKIs. However, few studies describe ponatinib for pediatric Ph+ALL; therefore, the efficacy, safety, and optimal dosage have not been determined. Here, we report a 3-year-old girl with Ph+ALL treated by a ponatinib-containing regimen with therapeutic drug monitoring in the plasma and cerebrospinal fluid (CSF). In our case, a ponatinib-containing regimen was able to keep minimal residual disease negative, and the pharmacokinetics (PKs) of plasma ponatinib resembled that previously reported in adults. Penetration to the CSF was extremely limited. Thus, ponatinib was feasible and effective for a child with Ph+ALL, although the plasma concentration of ponatinib varied significantly throughout the treatment. The appropriate dosage should be confirmed in a prospective trial, including a detailed PK study.