Evolving therapy of adult acute lymphoblastic leukemia: state-of-the-art treatment and future directions

Recent years have witnessed major advances that have improved outcome of adults with acute lymphoblastic leukemia (ALL). The emergence of the concept of measurable residual disease has fine-tuned our prognostic models and guided our treatment decisions. The treatment paradigms of ALL have been revolutionized with the advent of tyrosine kinase inhibitors targeting BCR-ABL1, monoclonal antibodies targeting CD20 (rituximab), antibody-drug conjugates targeting CD22 (inotuzumab ozogamicin), bispecific antibodies (blinatumomab), and CD19 chimeric antigen receptor T cell therapy (tisagenlecleucel). These highly effective new agents are allowing for novel approaches that reduce reliance on intensive cytotoxic chemotherapy and hematopoietic stem cell transplantation in first remission. This comprehensive review will focus on the recent advances and future directions in novel therapeutic strategies in adult ALL.

Extramedullary disease in APL: a real phenomenon to contend with or not?

In the last 2 decades an increasing number of patients reported with extramedullary involvement among relapsed acute promyelocytic leukemia (APL) patients. Several investigators related this phenomenon to the relatively new treatment of all-trans-retinoic-acid (ATRA). In this review article we will examine what has been reported in the medical literature on extramedullary disease in APL: the common sites to be involved, the clinical risk factors to its development, the role of ATRA and arsenic tri-oxide and the recommended treatment.

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.

Neurologic complications associated with intrathecal liposomal cytarabine given prophylactically in combination with high-dose methotrexate and cytarabine to patients with acute lymphocytic leukemia

Central nervous system (CNS) prophylaxis has led to a significant improvement in the outcome of patients with acute lymphocytic leukemia (ALL). Liposomal cytarabine (Enzon Pharmaceuticals, Piscataway, NJ; Skye Pharma, San Diego, CA), an intrathecal (IT) preparation of cytarabine with a prolonged half-life, has been shown to be safe and effective in the treatment of neoplastic meningitis. Liposomal cytarabine was given for CNS prophylaxis to 31 patients with newly diagnosed ALL. All patients were treated concurrently with hyper-CVAD chemotherapy (fractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) including high-dose methotrexate (MTX) and cytarabine on alternating courses. Liposomal cytarabine 50 mg was given intrathecally on days 2 and 15 of hyper-CVAD and day 10 of high-dose MTX and cytarabine courses until completion of either 3, 6, or 10 IT treatments, depending on risk for CNS disease. Five patients (16%) experienced serious unexpected neurotoxicity, including seizures, papilledema, cauda equina syndrome (n = 2), and encephalitis after a median of 4 IT administrations of liposomal cytarabine. Toxicities usually manifested after the MTX and cytarabine courses. One patient died with progressive encephalitis. After a median follow-up of 7 months, no isolated CNS relapses have been observed. Liposomal cytarabine given via intrathecal route concomitantly with systemic chemotherapy that crosses the blood-brain barrier such as high-dose MTX and cytarabine can result in significant neurotoxicity.

Ameliorating skin-homing receptors on malignant T cells with a fluorosugar analog of N-acetylglucosamine: P-selectin ligand is a more sensitive target than E-selectin ligand

Expression of E- and P-selectin ligands is required for T cell entry into skin. Sialyl Lewis X moieties are critical for ligand activity and are elevated on malignant skin-homing T cells. We hypothesize that these glycosylations are selectable targets for treating the dermal tropism associated with cutaneous lymphomas. In this study, we analyzed the efficacy of a novel 4-fluorinated analog of N-acetylglucosamine (GlcNAc) on E- and P-selectin ligands expressed by malignant skin-homing T cells. We also examined the specificity of 4-F-GlcNAc (2-acetamido-1,3,6-tri-O-acetyl-4-deoxy-4-fluoro-D-glucopyranose) action by contrasting the effects on sialyl Lewis X expression displayed by P-selectin glycoprotein ligand-1 (PSGL-1) with sialylated O-glycans expressed by CD43. Using parallel-plate flow analysis, we found that 4-F-GlcNAc elicited 5-fold more potent inhibition on P-selectin ligand activity than on E-selectin ligand activity. To determine whether glycosylations conferring E- and P-selectin ligand activities were inhibited, we analyzed the expression of sialyl Lewis X and sialyl-fucosylated core 2 O-glycan (CHO-131 antigen), respectively. We found that 4-F-GlcNAc treatment resulted in dose-dependent ablation of sialyl Lewis X and CHO-131 antigen expression on PSGL-1, whereas sialylated O-glycans on CD43 were minimally affected. These results indicate that 4-F-GlcNAc treatment can selectively downregulate the P-selectin ligand activity and potentially prevent dermal dissemination of cutaneous lymphomas.

CXCR4 chemokine receptors, histone deacetylase inhibitors and acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a malignancy with the potential to infiltrate the liver, spleen, lymph nodes and brain. The mechanism for selective homing of ALL cells to preferential sites has long been unclear. Recent reports indicate that the chemokine receptor CXCR4 is found on ALL cells and its ligand is highly expressed at sites associated with ALL-induced organ infiltration. This results in chemotaxis, or directed migration of leukemic cells from the bone marrow via the circulation to preferential sites of extramedullary organ infiltration. Because overexpression of CXCR4 on ALL cells is associated with high extramedullary organ infiltration and shorter disease-free survival, numerous pharmacological agents affecting CXCR4 have currently been investigated. The most promising data are available for histone deacetylase inhibitors (HDAIs), which have been shown to be safe and well tolerated in phase I clinical trials. In vitro, HDAIs extensively down-regulate CXCR4 protein and mRNA levels. As a result, the ability of CXCR4 ligand to induce cellular migration is impaired. Wider recognition of the role of CXCR4 in ALL and manipulation of this important mechanism may lead to novel approaches in the treatment and outcome of this disease.

Benefit of dexamethasone compared with prednisolone for childhood acute lymphoblastic leukaemia: results of the UK Medical Research Council ALL97 randomized trial

Corticosteroids are an essential component of treatment for acute lymphoblastic leukaemia (ALL). Prednisolone is the most commonly used steroid, particularly in the maintenance phase of therapy. There is increasing evidence that, even in equipotent dosage for glucocorticoid effect, dexamethasone has enhanced lymphoblast cytotoxicity and penetration of the central nervous system (CNS) compared with prednisolone. Substitution of dexamethasone for prednisolone in the treatment of ALL might, therefore, result in improved event-free and overall survival. Children with newly diagnosed ALL were randomly assigned to receive either dexamethasone or prednisolone in the induction, consolidation (all received dexamethasone in intensification) and continuation phases of treatment. Among 1603 eligible randomized patients, those receiving dexamethasone had half the risk of isolated CNS relapse (P = 0.0007). Event-free survival was significantly improved with dexamethasone (84.2% vs. 75.6% at 5 years; P = 0.01), with no evidence of differing effects in any subgroup of patients. The use of 6.5 mg/m(2) dexamethasone throughout treatment for ALL led to a significant decrease in the risk of relapse for all risk-groups of patients and, despite the increased toxicity, should now be regarded as part of standard therapy for childhood ALL.

Aleukaemic leukaemia cutis: case report and review of the literature

'Aleukaemic leukaemia cutis' or acute leukaemia confined to the skin is extremely rare, although skin involvement with underlying leukaemia is well recognized, and is associated with a poor prognosis. We report a case of isolated acute myeloid leukaemia (AML) in the skin. A literature review shows this to be commonly misdiagnosed. Its recognition is important, because early diagnosis should lead to more appropriate chemotherapy, and a better prognosis. These patients probably require therapy directed specifically to the skin, as well as to other extramedullary sites, such as the central nervous system, to prevent early relapse.

Treatment options for newly diagnosed patients with adult acute lymphoblastic leukemia

The treatment of adults with acute lymphoblastic leukemia (ALL) has been modeled on therapy developed for childhood ALL. The similarity between childhood and adult forms of this disease allows for inferences to be drawn from experience in the pediatric population. However, adults with ALL have far poorer outcome when compared to children. Some of this difference can be attributed in ability to tolerate intensive therapy coupled with an increased incidence of unfavorable cytogenetic subgroups and a decreased incidence of favorable cytogenetic subgroups. Treatment of adult ALL is typically divided into four broad categories: induction, consolidation, maintenance, and central nervous system prophylaxis. Despite three decades of clinical investigation for devising improved treatment programs for adults with ALL, no single program has emerged as the standard. Here we review classification, prognostic features, current treatment programs, and new advances as applied to adult patients with newly diagnosed ALL.

Inhibition of acute lymphoblastic and myeloid leukemias by a novel kinase inhibitor

In recent years, synthetic tyrosine kinase inhibitors have made a rapid transition from basic research to therapeutic application. These compounds represent a major clinical advance in the approach to cancer in their relative specificity of action and decreased toxicity. We report here the effects of a novel tyrosine kinase inhibitor CR4 that interferes with growth-promoting pathways to markedly inhibit the growth and survival of both Philadelphia-positive and -negative acute lymphoblastic leukemia (ALL) as well as acute myeloid leukemia (AML). While efficiently ablating leukemic cell growth, normal cell growth and differentiation remain unaffected by CR4. CR4 demonstrates an ability to inhibit the function of multiple growth-critical kinases and yet exhibits a low level of cytotoxicity. These findings suggest that CR4 may prove to be highly effective as a therapeutic agent.

Allosterically controllable maxizyme-mediated suppression of progression of leukemia in mice

Chronic myelogenous leukemia (CML) is a hematopoietic malignant disease associated with expression of a chimeric BCR-ABL gene. We recently succeeded in designing a novel allosterically controllable ribozyme, the maxizyme (Tanabe et al. Biomacromolecules 2000, 1, 108-117; Kuwabara et al. Biomacromolecules 2001, 2, 788-799), that not only specifically cleaves BCR-ABL mRNA and induces apoptosis in cultured CML cells but also shows significant inhibition against the growth of an established BV173 cell line in a mouse model (Tanabe et al. Nature 2000, 406, 473-474). As an extension of our studies, we tested the maxizyme against primary CML cells in the same mouse model. The maxizyme under the control of a tRNA(Val) promoter showed significant inhibition against the growth of the primary bone marrow cells from a Japanese patient with CML. Specifically, to examine the applicability of the maxizyme in the treatment of CML, we assessed the antitumor effect of the maxizyme in murine models of CML. Fourteen weeks after the injection of primary CML cells into a NOD-SCID mouse, the bone marrow of the mouse was filled with primary CML cells as a result of diffuse leukemia. In marked contrast, when maxizyme-expressing primary CML cells were injected, the mouse remained disease-free. These results further strengthen our earlier suggestion that the maxizyme technology might provide a useful approach to the treatment of CML.

Thyroid function in survivors of childhood acute lymphoblastic leukaemia: the significance of prophylactic cranial irradiation

OBJECTIVE

Focus on long-term side-effects after cancer therapy in childhood has become of the utmost importance. The hypothalamic-pituitary thyroid (HPT) axis is exposed to irradiation when some children are treated for acute lymphoblastic leukaemia (ALL) with prophylactic cranial irradiation (CIR). Whether this treatment causes hypofunction of the HPT axis remains controversial.

DESIGN

We measured plasma levels of total T3 (T3), total T4 (T4) and TSH before stimulation with TRH and plasma levels of TSH, 30 and 150 minutes after stimulation with TRH in 95 patients in first continuous remission of childhood ALL.

PATIENTS

Patients diagnosed with ALL before the age of 15 years between 1970 and 1991 and who were in first continuous remission and off treatment for at least one year were studied. The children were aged between 0.5 and 14.8 years (median: 3.9) at diagnosis of ALL. Thyroid function was assessed between 1.2 and 18.3 years (median: 7.6) after completion of therapy.

MEASUREMENTS

We measured T4 levels before, and compared TSH levels before and after, stimulation with TRH in patients who were treated with prophylactic CIR (15-24 Gy) (n = 38) (CIR group) with patients who were treated with chemotherapy only (n = 57) (non-CIR group).

RESULTS

We found that T3 and T4 levels were normal in all individuals (excluding the women who were on oral contraceptives). The median time from end of treatment to time at follow-up was 9.1 years in the non-CIR group vs. 4.2 years in the CIR group (P < 0.001), and the effect on follow-up time was significant (P = 0.04). It was estimated that just after irradiation, the TSH levels before and 30 and 150 minutes after TRH stimulation was 49% lower in the CIR group; however, after 4.0 years, TSH levels were not significantly different between the two groups. Although within normal limits, the T4 levels were significantly higher in the CIR group compared to the non-CIR group (P = 0.003). It was estimated that, just after the end of treatment, T4 was 19.9% higher in the CIR group. However, in the CIR group, the T4 level decreased significantly over time with -1.5% per year (P = 0.025), while the difference in the non-CIR group was not significant. There was no correlation between T4 and TSH levels and sex, age at diagnosis, age at the end of treatment or age at follow-up.

CONCLUSIONS

We conclude that, in our cohort of survivors of childhood ALL, prophylactic cranial irradiation of the central nervous system did not have an adverse effect on hypothalamo-pituitary-thyroid function within a median follow-up time of 8 years.

Value of high-dose cytarabine during interval therapy of a Berlin-Frankfurt-Munster-based protocol in increased-risk children with acute lymphoblastic leukemia and lymphoblastic lymphoma: results of the European Organization for Research and Treatment of Cancer 58881 randomized phase III trial

PURPOSE

The European Organization for Research and Treatment of Cancer 58881 study was designed to test in a prospective multicentric randomized trial the value of high-dose (HD) intravenous (IV) cytarabine (Ara-C) added to HD IV methotrexate (MTX) to reduce the incidence of CNS and systemic relapses in children with increased-risk acute lymphoblastic leukemia (ALL) or stage III and IV lymphoblastic lymphoma treated with a Berlin-Frankfurt-Munster (BFM)-based regimen.

PATIENTS AND METHODS

After completion of induction-consolidation phase, children with increased-risk (risk factor > 0.8 or T-lineage) ALL or stage III and IV lymphoblastic lymphoma were randomized to receive four courses of HD MTX (5 g/m(2) over 24 hours every 2 weeks) and four intrathecal administrations of MTX (Arm A) or the same treatment schedule with additional HD IV Ara-C (1 g/m(2) in bolus injection 12 and 24 hours after the start of each MTX infusion) (Arm B).

RESULTS

Between January 1990 and January 1996, 653 patients with ALL (593 patients) or lymphoblastic lymphoma (60 patients) were randomized: 323 were assigned to Arm A (without Ara-C) and 330 to Arm B (with Ara-C). A total of 190 events (177 relapses and 13 deaths without relapse) were reported, and the median follow up was 6.5 years (range, 2 to 10 years). The incidence rates of CNS relapse were similar in both arms whether isolated (5.6% and 3.3%, respectively) or combined (5.3% and 4.6%, respectively). The estimated 6-year disease-free survival (DFS) rate was similar (log-rank P =.67) in the two treatment groups: 70.4% (SE = 2.6%) in Arm A and 71.0% (SE = 2.5%) in Arm B. The 6-year DFS rate was similar for ALL and LL patients: 70.2% (SE = 1.9%) versus 76.3% (SE = 5.6%).

CONCLUSION

Prevention of CNS relapse was satisfactorily achieved with HD IV MTX and intrathecal injections of MTX in children with increased-risk ALL or stage III and IV lymphoblastic lymphoma treated with our BFM-based treatment protocol in which cranial irradiation was omitted. Disappointingly, with the dose schedule used in this protocol, HD Ara-C added to HD MTX, although well tolerated, failed to further decrease the incidence of CNS relapse or to improve the overall DFS.

Intrathecal chemotherapy

An unforeseen consequence of improved disease-free survival in many hematologic and solid tumor malignancies has been an increase in the incidence of disease recurrence in the leptomeninges. The recognition of the central nervous system (CNS) as a unique 'sanctuary' site has resulted in the development of therapeutic strategies specifically directed at the leptomeninges. Although therapeutic strategies have been successful in the prevention and treatment of CNS leukemia, there are still a paucity of therapeutic options for patients with neoplastic meningitis due to solid tumors or recurrent CNS leukemia. This article provides an overview of the pharmacology and toxicity of intrathecal agents that are commonly employed in the treatment and prevention of leptomeningeal disease, and describes new agents that are in the early stages of clinical development.

Central nervous system involvement in adult acute lymphocytic leukemia

With effective CNS prophylaxis, most adults with ALL may remain free of CNS leukemia. Several combinations of IT chemotherapy, high-dose systemic chemotherapy, and cranial irradiation have been used with varying results. Excellent prophylaxis can be achieved without cranial irradiation, and in view of the potential acute and long-term toxicity of radiation, these methods may be preferable. A prophylactic approach tailored to the risk of CNS leukemia was shown to be valuable in childhood ALL and in at least one adult study. Further studies should focus on defining risk groups for CNS leukemia and designing effective prophylaxis for each group. More research is needed to define the intensity and duration of treatment and the role of cranial irradiation in the treatment of isolated CNS relapses.

Effects of cranial radiation in children with high risk T cell acute lymphoblastic leukemia: a Pediatric Oncology Group report

Contemporary chemotherapy has significantly improved event-free survival among patients with T cell-lineage acute lymphoblastic leukemia (T-ALL). Unlike B-precursor ALL, most investigators are still using cranial radiation (CRT) and are hesitant to rely solely on intrathecal therapy for T-ALL. In this study we assessed the effects of CRT upon event-free survival and central nervous system (CNS) relapses in a cohort of children with high risk features of T cell leukemia. In a series of six consecutive studies (1987-1995) patients were non-randomly assigned their CNS prophylaxis per individual protocol. These protocols were based on POG 8704 which relied on rotating drug combinations (cytarabine/cyclophosphamide, teniposide/Ara-C, and vincristine/doxorubicin/6-MP/prednisone) postinduction. Modifications such as high-dose cytarabine, intermediate-dose methotrexate, and the addition of G-CSF, were designed to give higher CNS drug levels (decreasing the need for CRT), to eliminate epidophyllotoxin (decreasing the risk of secondary leukemia), and to reduce therapy-related neutropenia (pilot studies POG 9086, 9295, 9296, 9297, 9398). All patients included in this analysis qualified for POG high risk criteria, WBC >50000/mm3 and/or CNS leukemia. Patients without CNS involvement received 16 doses of age-adjusted triple intra-thecal therapy (TIT = hydrocortisone, MTX, and cytarabine) whereas patients with CNS disease received three more doses of TIT during induction and consolidation. Patients who received CRT were treated with 2400 cGy (POG 8704) or 1800 cGy (POG 9086 and 9295). CNS therapy included CRT in 144 patients while the remaining 78 patients received no radiation by original protocol design. There were 155 males and 57 females with a median age of 8.2 years. The median WBC for the CRT+ and CRT- patients were 186000/mm3 and 200000/mm3, respectively. CNS involvement at diagnosis was seen in 16% of the CRT+ and 23% of the CRT- groups. The complete continuous remission rate (CCR) was not significantly different for the irradiated vs. non-irradiated groups (P = 0.46). The 3-year event-free survival was 65% (s.e. 6%) and 63% (s.e. 4%) for the non-irradiated vs. the radiated group. However, the 3-year CNS relapse rate was significantly higher amongst patients who did not receive CRT; 18% (s.e. 5%) vs. 7% (s.e. 3%) in the irradiated group (P = 0.012). Our analysis in a non-randomized setting, suggests that CRT did not significantly correlate with event-free survival but omitting it had an adverse effect on the CNS involvement at the time of relapse.

Neurodevelopmental outcome of infants with acute lymphoblastic leukemia: a Children's Cancer Group report

BACKGROUND

Infants diagnosed with acute lymphoblastic leukemia (ALL) are considered the patient subgroup at the highest risk for central nervous system (CNS) disease, both at presentation and as an isolated extramedullary relapse. In addition, they are highly vulnerable to adverse developmental sequelae from CNS-directed therapy.

METHODS

Thirty patients younger than 12 months at diagnosis (12 males, 18 females) in first hematologic remission were evaluated after completion of ALL therapy (mean age = 62.1 months; standard deviation = 17.2 months; range = 38-102 months). CNS-directed treatment included very high dose infusions of methotrexate (MTX) and intrathecal cytarabine and MTX. Three patients had meningeal leukemia that required additional therapy. Children were administered the McCarthy Scales of Children's Abilities, and parents completed a sociodemographic questionnaire to obtain information about occupation and education.

RESULTS

Mean scores on all 6 cognitive and motor indices of the McCarthy Scales were in the average range (Verbal = 52.0; Perceptual = 53.6; Quantitative = 49.6; General Cognitive Index [GCI] = 102.1; Memory = 49.2; Motor = 51.0). Score distributions for each neurodevelopmental index were comparable to age-based population standards. One patient obtained a GCI that exceeded 2 standard deviations above the mean; none scored more than 2 standard deviations below. There was no report of developmental disabilities or neurologic disorders for any of the patients. Risk factors, including age at diagnosis, gender, additional CNS-directed treatment, and family socioeconomic status, were not associated with developmental outcome.

CONCLUSIONS

Test findings indicated a generally positive neurodevelopmental outcome for ALL patients diagnosed in infancy who were treated with very high dose MTX as CNS-directed therapy. Combined with the reduction in the isolated CNS relapse rate achieved by the Children's Cancer Group (CCG) clinical trial CCG-107, the results of this study represent a substantial improvement in neurodevelopmental outcome for very young patients compared with infants treated for ALL in the past.

Cognitive and academic late effects among children previously treated for acute lymphocytic leukemia receiving chemotherapy as CNS prophylaxis

OBJECTIVE

Examine cognitive and academic late effects among children and adolescents who had received central nervous system (CNS) prophylactic chemotherapy alone for acute lymphocytic leukemia (ALL); none had received whole brain radiation therapy (RT).

METHOD

Subjects included 47 children and adolescents from 5 to 22 years of age who were treated on the same protocol and had been off treatment from 2 to 7 years at the time of assessment.

RESULTS

As a group the survivors displayed generally average performance on measures of cognitive and academic abilities, although they differed from normative means on tests of nonverbal skills. Girls performed more poorly than the normative sample on nonverbal tasks, while no differences were found for boys. Age at diagnosis and time off treatment were not significantly associated with cognitive and academic functioning for survivors of this particular chemotherapy-only protocol.

CONCLUSIONS

Data were interpreted to support generally modest potential late effects in specific areas for children and adolescents surviving ALL. These findings suggest a need for monitoring nonverbal cognitive skills for childhood survivors of ALL, particularly for girls.

Early intensification of intrathecal chemotherapy virtually eliminates central nervous system relapse in children with acute lymphoblastic leukemia

Central nervous system (CNS) relapse has been an obstacle to uniformly successful treatment of childhood acute lymphoblastic leukemia (ALL) for many years. We therefore intensified intrathecal chemotherapy (simultaneously administered methotrexate, hydrocortisone, and cytarabine) for 165 consecutive children with newly diagnosed ALL enrolled in Total Therapy Study XIIIA from December 1991 to August 1994. The 64 patients (39%) who had 1 or more blast cells in cytocentrifuged preparations of cerebrospinal fluid at diagnosis, with or without associated higher-risk features, received additional doses of intrathecal chemotherapy during remission induction and the first year of continuation treatment. Patients with higher-risk leukemia, regardless of cerebrospinal fluid findings, also received additional doses of intrathecal chemotherapy during the first year of continuation treatment. Cranial irradiation was reserved for patients with higher-risk leukemia (22% of the total). The 5-year cumulative risk of an isolated CNS relapse among all 165 patients was 1.2% (95% confidence interval, 0% to 2.9%), whereas that of any CNS relapse was 3.2% (0. 4% to 6.0%). The probability of surviving for 5 years without an adverse event of any type was 80.2% +/- 9.2% (SE). Our results suggest that early intensification of intrathecal chemotherapy will reduce the risk of CNS relapse to a very low level in children with ALL, securing a higher event-free survival rate overall.

Prophylaxis and treatment of neoplastic meningeosis in childhood acute lymphoblastic leukemia

The introduction of cranial radiotherapy (CRT) has provided efficient control of overt or subclinical meningeosis in acute leukemia. Especially due to the long-term toxicity of CRT, reduction or elimination of radiotherapy appeared mandatory after cure rates of more than 70% had been achieved in acute lymphoblastic leukemia (ALL). Several large clinical trials of the Berlin-Frankfurt-Münster (BFM) Study Group with more than 3500 patients since 1981 have demonstrated that intensive systemic and intrathecal chemotherapy without or with limited CRT can efficiently prevent central nervous system (CNS) relapses in a large percentage of patients. However, only in low-risk patients prophylactic radiotherapy can be completely and safely replaced by conventional doses of methotrexate. In addition, reduction of chemotherapy in low-risk ALL increased the rate of relapses with CNS involvement. Thus, only a combination of multidrug induction, high-dose methotrexate (HD-MTX) consolidation, and reintensification allowed safe elimination of CRT in low-risk ALL. This approach combined with CRT with 12Gy and 18 Gy in medium and high risk ALL, respectively, reduced the incidence of relapses with CNS involvement to less than 5% (trial ALL-BFM 86). Patients with inadequate response to therapy, or with T-cell ALL, or with overt CNS disease are at particularly high risk for relapse with CNS involvement, and require more systemic and intrathecal chemotherapy combined with cranial irradiation. In B-cell ALL, short intensive chemotherapy pulses including HD-MTX could completely replace radiotherapy. In AML, post-consolidation CRT appears to be advantageous with regard to control of extramedullary as well as systemic relapses.

Treatment of childhood leukemia

The development of successful therapy for most children with acute lymphoblastic leukemia can be attributed to sequential clinical studies that show the importance of combination chemotherapy, sanctuary-specific treatment, and supportive care measures. The relative resistance of acute myelogenous leukemia to chemotherapy led to strategies that include dose-intensified chemotherapy and bone marrow transplantation. The improvement in long-term survival for children with acute leukemia has been gratifying but also has been associated with late effects that underscore the need for careful follow-up and for designing risk-adapted therapies.

Low incidence of CNS relapse with cranial radiotherapy and intrathecal methotrexate in acute lymphoblastic leukemia

OBJECTIVES

To assess the incidence of isolated central nervous system (CNS) relapses in patients of acute lymphoblastic leukemia (ALL) treated with a protocol containing cranial irradiation and intrathecal methotrexate as CNS directed therapy.

DESIGN

Prospective non randomized study.

SETTING

Department of Medical Oncology, Tata Memorial Hospital.

SUBJECTS

623 children of ALL on MCP 841.

METHODS

CNS relapse was diagnosed, if upon examination of the CSF, more than 50 cells/microliter were observed, or a count of 5 cells which were unequivocally lymphoblasts.

RESULTS

The incidence of isolated CNS relapse was 1.75% with the use of this treatment. Age, sex, white blood cell count, platelet count, lactic dehydrogenase and immunophenotyping were not significantly related to isolated CNS relapse.

CONCLUSION

A low incidence of isolated CNS relapse demonstrates the adequacy of the presymptomatic CNS therapy.

Intellectual performance after presymptomatic cranial radiotherapy for leukaemia: effects of age and sex

Cognitive outcome, as measured by verbal and performance IQs, was compared in 35 girls and 47 boys who were in first remission for acute lymphoblastic leukaemia. All children had received presymptomatic cranial radiotherapy and intrathecal methotrexate. The mean age at diagnosis was 4.2 years and the mean elapsed time from initial diagnosis to intellectual assessment was 7.1 years. Results showed that children irradiated before the age of 4 years were impaired in certain aspects of non-verbal ability, as well as in measures of short term memory and attention, calculated by factor scores derived from selected subtests of the IQ test. Subtests requiring verbal and non-verbal reasoning showed the greatest impairment after early diagnosis and treatment. In addition girls were selectively impaired in verbal IQ and other aspects of verbal ability, with the degree of impairment exacerbated by early treatment. No relationship was found between degree of impairment and either time since treatment or number of methotrexate injections. It is concluded that early age at irradiation increases the risk of impaired intellectual outcome, particularly in girls.

Prevention and treatment of meningeal leukemia in children

The prevention of meningeal leukemia has long been a keystone in its cure. The need was recognized when it became apparent in the 1950s and 1960s that meningeal relapse heralded hematologic relapse and a fatal course and that its incidence increased as systemic chemotherapy became more effective in controlling hematologic and visceral leukemia. Evasion of a biologic safety net, the blood-CSF barrier, is required to prevent meningeal leukemia. Three methods are used: meningeal radiotherapy, intrathecal administration of antileukemia drugs, and high-dosage intravenous antileukemia drugs. Recent and current clinical studies reflect a continuing dialogue about which methods are preferable and under what circumstances. For prevention of meningeal leukemia, extended intrathecal therapy and intensive systemic chemotherapy appear to be as effective as radiotherapy for most patients. For treatment of overt meningeal leukemia, meningeal radiotherapy may be necessary. However, its administration compromises subsequent systemic chemotherapy so that delay may be advisable to allow intensive systemic chemotherapy for control of concurrent hematologic and visceral leukemia, whether clinically evident or not. For patients with meningeal leukemia at diagnosis, cranial irradiation may be delayed or possibly omitted if evidence of disease is minimal and intrathecal and systemic chemotherapy are intensive. For those who develop meningeal leukemia while on therapy or after its completion, cranial or craniospinal irradiation is probably required as well as intensive intrathecal and systemic chemotherapy. Hopefully, current and future studies will dispel the uncertainties and better quantitate risks and benefits of alternative methods. Whatever method is used, careful attention to technical details is required to assure optimal efficacy at the least possible expense in immediate toxicity and late sequelae.

Therapy of B-cell acute lymphoblastic leukaemia in childhood: the BFM experience

In 1981 the BFM group introduced a new treatment strategy for B-ALL based on two alternating 5-day courses of chemotherapy delivered in short intervals up to a total of eight. The therapy courses were composed of fractionated cyclophosphamide, MTX 0.5 g/m2 (24-h infusion), i.t. MTX therapy, and ara-C/VM26 alternating with doxorubicin. The development of the therapy strategies during the subsequent two studies was characterized by shortening treatment duration from eight to six courses, and intensification of CNS chemotherapy in study ALL-BFM-83, and the introduction of HD-MTX (5 g/m2, 24-h infusion) in study ALL-BFM-86. In study ALL-BFM-81, CNS therapy consisted of ID-MTX in combination with i.t. MTX and RX. CNS-positive patients received complete neuroaxis irradiation. In study ALL-BFM-83, CNS chemotherapy was intensified by adding dexamethasone, while MTX/ara-C were administered intraventricularly. Spinal irradiation for CNS-positive patients was omitted. In study ALL-BFM-86, i.t. MTX/ara-C/prednisolone therapy was introduced in combination with HD-MTX but the intraventricular route of drug administration was no longer used. Radiotherapy was omitted completely. In all, 87 patients were enrolled, 22 (eight CNS positive) in study ALL-BFM-81, 24 (seven CNS positive) in study ALL-BFM-83, and 41 (none CNS positive) in study ALL-BFM-86. The estimated 5-year duration of EFS was 40% in study ALL-BFM-81, 50% in study ALL-BFM-83, and 78% in study ALL-BFM-86 (minimal follow-up 36 months). Nineteen of 24 relapses occurred while on therapy or shortly thereafter. In study ALL-BFM-81, the CNS was the most frequent site of failure. In ALL-BFM-83 there were no isolated CNS relapses but more BM relapses occurred. In ALL-BFM-86 localized manifestations were the predominant site of failure, no isolated BM relapses occurred, and only one CNS relapse was diagnosed. No single parameter exerted a consistent influence on outcome with one exception. The presence of residual disease after the first two courses was correlated with an increased risk of therapy failure. Our conclusions from the three studies are listed below. An intensive, short-pulse therapy delivered within a 4 month period is highly effective in the treatment of B-ALL. Prolonged therapy duration is of no value. In addition to fractionated cyclophosphamide-ifosfamide, a 24-h infusion of HD-MTX5 g/m2 in conjunction with an i.t. therapy is a very important component for prevention of both systemic and CNS relapses.(ABSTRACT TRUNCATED AT 400 WORDS)

Advances in therapy for childhood non-B-lymphoblastic leukaemia

The majority of therapeutic gains for patients with ALL have come from prospectively planned clinical trials. Beginning in the 1970s, series of well-designed protocols have produced valuable information that has permitted the development of curative therapy for more than two-thirds of patients. This success emphasizes the importance of controlled, carefully analysed therapeutic studies, which pay dividends for many years by providing a sound basis for future developments. Experienced biostatisticians should be involved early in the development of clinical trials to ensure that research questions can be reliably answered in terms of the size and composition of the patient sample and in terms of accrual time. Despite extensive pre-planning, a protocol may require early termination due to unexpected results that compromise the integrity of the initial design (Rivera et al, 1985). Thus, periodic treatment assessment of the trial is crucial to a successful outcome. Extended follow-up of patients is a requirement in every leukaemia study since relapses may occur many years after diagnosis, especially if patients have a lower risk of treatment failure (Rivera et al, 1979). The quality of long-term survival must also be well documented because all protocols include toxic therapy (Ochs and Mulhern 1988). Every physician treating children with ALL would like to select therapy that is both effective and well tolerated. Unfortunately, this is not always possible when patients have high-risk features. Secondary AML, deaths in remission and fatal organ toxicity (Steinherz, 1991c) are equally devastating complications of current chemotherapy for ALL, and no single protocol can be recommended over any other. Patients with ALL may be equally well served by any of several different protocols. The practice of administering 6MP + MTX alone and usually orally as continuation treatment has been virtually abandoned. Today, most children receive intensified chemotherapy in one schedule or another, including good-risk patients on POG protocols who, although treated largely with antimetabolite-based programmes, receive high-dose chemotherapy during the initial 6 months of treatment. In view of the more favourable results attained with reinduction therapy in recent CCG studies, these investigators also recommend such an approach for children with better-risk ALL. We fully agree. Regrettably, with the success of current regimens for higher-risk ALL, it has not been possible to exclude all toxic agents that may induce serious late complications.(ABSTRACT TRUNCATED AT 400 WORDS)

Therapy and prognostic factors in adult acute lymphoblastic leukaemia

In acute lymphoblastic leukaemia (ALL) substantial progress has been achieved within the last few years. Complete remission rates up to 95% can now be achieved in children and 70-85% in adults; disease free survival rates are 70 and 30% respectively. To improve results further high dose treatment has been included, particularly to overcome drug resistance and to reach cytostatic levels in the sanctuary sites, such as the central nervous system. High dose cytarabine in combination with other cytostatic drugs, preferentially anthracyclines, seems to be of benefit for high risk adult ALL patients. High dose methotrexate, mostly explored in childhood ALL, is now also included in a variety of combinations in the treatment of adult ALL, but its effectiveness remains to be established. Substantial progress has been achieved in adult T-ALL and B-ALL with survival rates of 40-50%. The optimal form and duration of maintenance therapy in adult ALL is not yet clear but general omission of maintenance leaves patients with an inferior outcome. Which subgroups of adult ALL require maintenance and in what form still requires investigation. In recent adult ALL trials with intensive chemotherapy similar prognostic factors for disease free survival have emerged. Of adverse influence are delayed time to reach CR (more than 4/5 weeks), a high initial white blood cell count, higher age (above 50 or 60 years), and probably the immunological subtypes pre-T-ALL, pre-B-ALL, My(+)-ALL; of very adverse influence in elderly patients is the karyotype t(9;22) or the corresponding BCR/ABL gene rearrangement. High risk adult ALL patients with one or more of these adverse factors are candidates for allogeneic or autologous bone marrow transplantation in first remission. Whether all adult ALL patients are candidates for BMT in first CR is currently being explored in large prospective randomized trials.

Central nervous system directed therapy in acute lymphoblastic leukaemia

CNS-directed treatment is an essential component of therapy for both children and adults with acute lymphoblastic leukaemia. The choice between combinations of i.t. drugs, radiotherapy and high-dose systemic chemotherapy is not a clear one and will depend on the age of the patient, the type of leukaemia and indeed the available treatment facilities. A plea is made for any prospective trials of CNS-directed therapy to incorporate formal assessment of neuropsychological performance, and in the young child, of growth and pubertal progression.

High incidence of meningeal leukemia in lymphoid blast crisis of chronic myelogenous leukemia

Fifteen patients with lymphoid blast crisis of chronic myelogenous leukemia (LyBC-CML) and five patients with acute lymphoblastic leukemia converting to Philadelphia-positive (Ph+) chronic myeloid leukemia (ALL Ph + CML) were followed. Seven of 15 (46.7%) LyBC-CML patients developed meningeal leukemia within a median period of 6 months (range 2-11 months), while there was no medullary relapse. Five of these responded well to triple intrathecal therapy. In the ALL Ph + CML patients, in spite of central nervous system (CNS) prophylaxis with IT MTX and 18 Gy cranial radiation, two of five patients (40%) experienced meningeal leukemia, one isolated and the other with medullary relapse. The data confirm that LyBC-CML patients experience a high incidence of meningeal leukemia. The role of CNS prophylaxis is not very clear, but its use may delay development and reduce morbidity due to CNS disease.

Extended triple intrathecal chemotherapy trial for prevention of CNS relapse in good-risk and poor-risk patients with B-progenitor acute lymphoblastic leukemia: a Pediatric Oncology Group study

PURPOSE

The Pediatric Oncology Group (POG) acute leukemia in childhood (ALinC) 13 study tested two treatment regimens that used different CNS chemoprophylaxis for children older than 12 months with non-T, non-B acute lymphoblastic leukemia (ALL) and with no demonstrable CNS disease at diagnosis.

PATIENTS AND METHODS

With the first regimen, standard (S), six injections of triple intrathecal chemotherapy (TIC), consisting of methotrexate (MTX), hydrocortisone (HC), and cytarabine (ara-C), were administered during intensification treatment and at every-8-week intervals throughout the maintenance phase for 17 additional doses. The second regimen, standard and MTX pulses (SAM), also specified six TICs during intensification, but substituted every-8-week pulses of intermediate-dose parenteral methotrexate (IDM; 1 g/m2) for the 17 maintenance TIC injections, with a low-dose intrathecal (IT) MTX boost administered with the first four maintenance IDM pulses. Otherwise, systemic therapy on regimen SAM was identical to regimen S. There were 1,152 patients randomized to the S and SAM regimens after stratification by risk group (age/leukocyte count) and immunophenotype.

RESULTS

The 5-year probabilities (+/- SE) of an isolated CNS relapse were regimen S: good risk (n = 381), 2.8% +/- 1.3%; poor risk (n = 196), 7.7% +/- 3.2%; good + poor risk (n = 577), 4.7% +/- 1.5%; regimen SAM: good risk (n = 388), 9.6% +/- 2.2%; poor risk (n = 187), 12.7% +/- 4.2%; good + poor risk (n = 575), 10.9% +/- 2.2%. In poor-risk patients, approximately one third of the isolated CNS relapses occurred before preventive CNS therapy was begun at week 9. Hence, regimen S has provided better CNS preventive therapy for both good- and poor-risk patients (P < .001 overall). The difference is statistically significant for good-risk patients (P < .001), but not for poor-risk patients (P = .20). Neither treatment has shown a significant advantage in terms of general outcome.

CONCLUSION

TIC injections extended throughout the intensification and maintenance periods are superior to IDM pulses for prevention of CNS leukemia. Our results with TIC seem comparable with those achieved with other contemporary methods of CNS preventative therapy. Thus, extended TIC affords a reasonable alternative to CNS irradiation plus upfront IT MTX for patients with B-progenitor ALL.