Leukemia relapse in long-term survivors of acute leukemia

Nucleobase and Nucleoside Analogues: Resistance and Re-Sensitisation at the Level of Pharmacokinetics, Pharmacodynamics and Metabolism

Antimetabolites, in particular nucleobase and nucleoside analogues, are cytotoxic drugs that, starting from the small field of paediatric oncology, in combination with other chemotherapeutics, have revolutionised clinical oncology and transformed cancer into a curable disease. However, even though combination chemotherapy, together with radiation, surgery and immunotherapy, can nowadays cure almost all types of cancer, we still fail to achieve this for a substantial proportion of patients. The understanding of differences in metabolism, pharmacokinetics, pharmacodynamics, and tumour biology between patients that can be cured and patients that cannot, builds the scientific basis for rational therapy improvements. Here, we summarise current knowledge of how tumour-specific and patient-specific factors can dictate resistance to nucleobase/nucleoside analogues, and which strategies of re-sensitisation exist. We revisit well-established hurdles to treatment efficacy, like the blood-brain barrier and reduced deoxycytidine kinase activity, but will also discuss the role of novel resistance factors, such as SAMHD1. A comprehensive appreciation of the complex mechanisms that underpin the failure of chemotherapy will hopefully inform future strategies of personalised medicine.

Expression and significance of vascular endothelial growth factor A and C in leukemia central nervous system metastasis

Metastasis to the central nervous system (CNS) is an obstacle for leukemia treatment, the mechanisms of which remain to be elucidated. VEGF-A and VEGF-C are suspected to participate in this process. Paired of cerebrospinal fluid (CSF) and serum samples were collected from leukemia and control cases. Levels of VEGF-A and VEGF-C in both CSF (VEGF-ACSF, VEGF-CCSF) and serum (VEGF-ASerum, VEGF-CSerum) were detected by ELISA. Our data show that higher levels of VEGF-ACSF are closely related to CNS leukemia (CNSL), and VEGF-ACSF may be a better predictor than the other risk factors elucidating the pathogenesis and development of CNSL.

Triple intrathecal therapy without cranial irradiation for central nervous system preventive therapy in childhood acute lymphoblastic leukemia

BACKGROUND

To evaluate the treatment results of central nervous system preventive therapy (CNSP) with triple intrathecal therapy (TIT) alone in children with acute lymphoblastic leukemia (ALL).

METHODS

We retrospectively studied a cohort of 59 patients with median follow-up time 50.6 months (range: 27-80 months) at a single institution in Taiwan. Patients with ALL were classified in risk groups at diagnosis. TPOG-ALL-93 protocols and TPOG-ALL-2002 protocols were used. Both protocols were for multicenter studies in Taiwan and contained protocols for standard-risk (SR), high-risk (HR), and very-high-risk (VHR) patients. In this study, we used TIT alone for CNSP. In all ALL patients, methotrexate, hydrocortisone, and cytarabine were given at age-dependent doses.

RESULTS

As of October 2006, patients had a 3-year event-free survival and an overall survival 89.4 +/- 4.1% (S.E.) and 93.1 +/- 3.3%, respectively. Under TIT no patients had complications such as seizure, encephalitis, or infection, and no morbidities like those caused by cranial irradiation. In this study, we used TIT alone for CNSP and had no CNS relapse.

CONCLUSIONS

In the context of effective systemic therapy, TIT alone appears to be effective CNSP for most patients with ALL.

Prognostic Significance of Blasts in the Cerebrospinal Fluid Without Pleiocytosis or a Traumatic Lumbar Puncture in Children With Acute Lymphoblastic Leukemia: Experience of the Dutch Childhood Oncology Group

Purpose

To determine the significance of blasts in the CSF without pleiocytosis and a traumatic lumbar puncture in children with acute lymphoblastic leukemia (ALL).

Patients and Methods

We retrospectively studied a cohort of 526 patients treated in accordance with the virtually identical Dutch protocols ALL-7 and ALL-8. Patients were classified into five groups: CNS1, no blasts in the CSF cytospin; CNS2, blasts present in the cytospin, but leukocytes less than 5/μL; CNS3, blasts present and leukocytes more than 5/μL. Patients with a traumatic lumbar puncture (TLP; > 10 erythrocytes/mL) were classified as TLP+ (blasts present in the cytospin) or TLP− (no blasts).

Results

Median duration of follow-up was 13.2 years (range, 6.9 to 15.5 years). Event-free survival (EFS) was 72.6% (SE, 2.5%) for CNS1 patients (n = 304), 70.3% (SE, 4.7%) for CNS2 patients (n = 111), and 66.7% (SE, 19%) for CNS3 patients (n = 10; no significant difference in EFS between the groups). EFS was 58% (SE, 7.6%) for TLP+ patients (n = 62) and 82% (SE, 5.2%) for TLP− patients (n = 39; P < .01). Cox regression analysis identified TLP+ status as an independent prognostic factor (risk ratio, 3.5; 95% CI, 1.4 to 8.8; P = .007). Cumulative incidence of CNS relapses was 0.05 and 0.07 in CNS1 and CNS2 patients, respectively (not statistically significant).

Conclusion

In our experience, the presence of a low number of blasts in the CSF without pleiocytosis has no prognostic significance. In contrast, a traumatic lumbar puncture with blasts in the CSF specimen is associated with an inferior outcome.

Risk of Adverse Events After Completion of Therapy for Childhood Acute Lymphoblastic Leukemia

Purpose

We studied the frequency, causes, and predictors of adverse events in children with acute lymphoblastic leukemia (ALL) who had completed treatment on contemporary clinical protocols between 1984 and 1999. Our goal was to use the information to further refine therapy and advance cure rates.

Methods

Cumulative incidence functions of any post-treatment failure or any post-treatment relapse were estimated by the method of Kalbfleisch and Prentice and compared with Gray's test. The Cox proportional hazards model was used to identify independent prognostic factors.

Results

Of the 827 patients who completed all treatment while in initial complete remission, 134 patients subsequently had major adverse events, including 90 leukemic relapses, 40 second malignancies, and four deaths in remission. The cumulative incidence of any adverse event was 14.0% ± 1.2% (SE) at 5 years and 16.9% ± 1.4% at 10 years. The risk of any leukemic relapse was 10.0% ± 1.1% at 5 years and 11.4% ± 1.2% at 10 years. Male sex was the only independent predictor of relapse (hazard ratio, 1.74; 95% CI, 1.11 to 2.74; P = .02).

Conclusion

Further treatment refinements for children with ALL should aim not only to decrease the leukemic relapse rate, but also to reduce the risk of development of second malignancies.

Late relapses after treatment for acute lymphoblastic leukemia in childhood: a population-based study from the Nordic countries

Seven late relapses of acute lymphoblastic leukemia occurring 5.5 to 12.3 years after cessation of therapy are reported in 986 patients who had discontinued treatment for leukemia acquired before the age of 15. The study covers patients from the five Nordic countries. Of the 434 patients with ALL who had passed 5 years of follow-up without recurrence, seven have subsequently relapsed so far; an estimated cumulative proportion of 6.9% within the 10 years. In addition, we report a girl 15.9 years old at diagnosis who relapsed 7.3 years after cessation of therapy. These findings confirm that "cure" of acute lymphoblastic leukemia treated in the 1970s cannot be considered definite, even 5 years after discontinuation of therapy.

Clinical value of long-term maintenance chemotherapy in 5-year survivors of acute leukemia

We investigated whether long-term follow-up of 5-year or longer survivors of acute leukemia might provide some information concerning cure-oriented chemotherapeutic strategy. By sending a questionnaire form to major medical institutions throughout the country, data of 2202 5-year or longer survivors of acute leukemia was obtained as of 30 June 1988. There were 1607 children and 595 adults. In order to investigate the data further, they were divided into four periods according to the year of diagnosis: before 1969, 1970-1974, 1975-1979 and 1980-April 1983. As regards remission induction regimens, vincristine plus prednisolone (VP) was the most popular in childhood acute lymphoblastic leukemia (ALL) throughout these four periods. In adult acute non-lymphoblastic leukemia (ANLL), daunomycin (DM), cytosine arabinoside (ard-C), 6-mercaptopurine (6MP), prednisolone (STH) (DCMP) or behenoyl ara-C, DM, 6-MP, STH (BH-AC.DMP) was the most popular since the latter half of the 1970s. Both in childhood ANLL and adult ALL, there was no predominant regimen whatsoever. In an analysis of survival curves for the above four periods, each survival plateau for childhood ALL rose over time with statistical significance, reaching over 90% in the 1980s, whereas those for adult ANLL were not so, suggesting that newer ANLL regimens in the 1980s did not play a successful role in cure-oriented therapy. Whether duration of post-remission chemotherapy could be a prognostic factor for these survivors was studied by dividing the duration as follows: less than one year, 1-2, 2-3, 3-5 and more than 5 years. A therapeutic gain, with a cure rate of over 90%, was observed in childhood ALL patients treated with chemotherapy for 5 years or longer. In adult ANLL patients, results were similar with chemotherapy groups of both less than one year and 5 years or longer. This suggests that risk-adapted therapy is an optimal strategy for cure of adult ANLL as well as childhood ALL.