Cognitive Neurotoxicity in Children Treated for Acute Lymphoblastic Leukemia Using High- Dose Methotrexate Daniel Armstrong, Ph.D. Mailman Center for Child Development Department of Pediatrics University of Miami Miller School of Medicine And Holtz Children’s Hospital at the University of Miami/Jackson Medical Center

Background  Prior to 1986, CNS prophylaxis for ALL involved CRT (18-24 Gy) with or without intrathecal methotrexate Cognitive neurotoxicity was common, with learning difficulties in the areas of processing speed, visual-motor integration, attention and concentration, and memory. Math abilities most affected

Background  Most of the research on cognitive neurotoxicity associated with MTX has been involved the POG-CCG-COG approach to ALL treatment  There are few data on cognitive neurotoxicity looking at other approaches (e.g., Capizzi; BFM with 5g/m 2 X 4) to ALL treatment

Background  POG 8602 eliminated CRT and used triple intrathecal chemotherapy (TIT) for CNS prophylaxis (methotrexate, hydrocortisone, ARA-C) Transient white matter changes noted early on MR, but these resolved (Nitschke et al, 1990). No cognitive changes noted at 1-year follow-up after diagnosis, but difficulties in delayed recall, general non-verbal abilities, attention, motor speed, and visual motor integration found at completion of treatment (Brown et al, 1992) Females at more likely to have cognitive deficits

Background  POG 9005 compared intermediate dose IV-MTX (1g/m 2 ) with oral MTX in different combinations with mercaptopurine (oral vs. IV). The original study involved comparison of TIT vs MTX only for CNS prophylaxis, but all shifted to TIT after higher than anticipated CNS relapse with MTX only Acute neurotoxicity (seizures, imaging abnormalities) found for 7.8% of 1304 patients (Mahoney et al., 1998).

Background  Limited institution study involving 54 children treated on POG 9005 No acute neurotoxicity All received non-contrast CT, Neuropsychological Evaluation

Background  40% had CT abnormalities Calcifications: 50%  76% at the Gray-White Junction  8% at lateral ventricles  6% frontal  4% basal ganglia, parietal, or temporal White Matter Changes: 30%  55% peri-ventricular  30% at lateral ventricles  7% frontal  7% posterior white matter Both Calcifications and WMC: 20%

POG 9005 Outcomes %

POG 9005: Percent Classifications of Verbal IQ, Performance (non-verbal) IQ, Reading, Math, Visual-Motor Integration, and Processing Speed Measure<70 (Impaired)71-85 (Below Average 85 (Average/Above Average Verbal IQ15%23%61% Performance IQ20% 56% WJR Reading2%8%69% WJR Math8%10%61% VMI-Visual Motor Integration 5%25%64% WJR Processing Speed 5%18%64%

POG 9005: Percent of Classifications Based on Memory Scores (WRAML) Measure<7 (Impaired)8-9 (Below Average) >9 (Average or Above Average) Picture Memory 21%25%39% Design Memory 38%23%26% Story Memory30%21%39% Verbal Learning 25%11%51%

POG 9005: Percent Classification by Conners’ Continuous Performance Scores (CPT-Attention) CPT Scale>65 (Clinically Significant) <65 (Within Normal Range) Omission Errors43%57% Commission Errors2%98% Sustained Attention15%85% Inter-stimulus Interval Change 25%75%

Background  POG 9605 expanded on 9005, with HD-MTX and TIT Single institution study (Montour-Proulz et al., 2005) with 24 children found:  Mean VIQ=87, PIQ=84, Verbal Memory=83, Visual Memory=88.  78% had MR abnormalities at some point in study COG (ALTE0131) late effects study involving MR-FLAIR and Neuropsychological function now underway

Questions  Mechanism Vascular leading to calcification  Anti-folate effects of MTX Disruptions in the folate/adenosine pathways Elevated homocysteine (Kishi et al., 2003; Quinn et al., 2004 White matter changes/demyelination Pharmacogenetic risk  Why only 40% affected?

The Neurodevelopmental Model Treatment-Academic Linkages Cranial Radiation Chemotherapy (MTX, Steroids) Surgery Interrupted Myelination Calcification Failure of Connecting Structure Development Processing Speed Visual Memory Visual-Motor Integration Attention & Concentration Organization & Planning Structural Damage Reading (Comprehension ) Math (Calculations) Handwriting Shunt Seizure Genetics Sensory Impairment Other Impairment

Questions  Can outcomes be predicted using an interactive model of defined risk (genetic, pharmacologic, structural, and acute events) and neurodevelopmental trajectory?

Emerging Cognitive Deficits: Developmental Patterns Gross Motor Skills Language Skills Attention Fine Motor Skills Visual-Spatial Motor Skills

Emerging Cognitive Deficits: Developmental Patterns Gross Motor Skills Language Skills Attention Fine Motor Skills Visual-Spatial Motor Skills

Methotrexate Neurotoxicity Projects  Overall Project Goals: Determine the incidence and severity of MTX neurotoxicity associated with Capizzi and HD-MTX treatment Identify risk factors and possible mechanisms for neurotoxicity associated with MTX that lead to cognitive impairment

Methotrexate Neurotoxicity Project Purposes Project 1: Describe neurocognitive development in children with ALL at 3 time points Project 2: Identify host polymorphisms that may predict who, among the treated population, are at increased risk for neurocognitive toxicity. Project 3: Determine whether acute, transient episodes of neurologic toxicity reflect similar biochemical vulnerability and predict neurocognitive loss. Project 4: Study the pathophysiology of neurologic dysfunction though an assessment of the impact of MTX on folate dependant biochemical pathways. Project 5: Identify areas of selective vulnerability within the CNS that may predict and/or correlate with neurocognitive outcome using diffusion tensor imaging.

Methotrexate Neurotoxicity COG AALL0232 & AALL0434  Enroll 432 children with high risk ALL treated on AALL0232 or AALL0434, 72 sibling controls  Both Studies involve comparison of HD-MTX with Capizzi Methotrexate for Consolidation AALL0232 also compares dexamethasone with prednisone during induction AALL0434 adds Nelarabine

Neurocognitive Outcomes Project  Design Prospective, repeated measures design with neurocognitive function as the primary outcome variable (T1: end of induction, T2: 12 months after remission; T3: 12 months off-treatment)  Neurocognitive Outcomes  SNP modeling  Folate dependent biochemical pathways  Diffusion Tensor imaging  Acute neurotoxic events

Neurocognitive Outcomes Project  2 age cohorts Younger (12.0 months months at diagnosis) Older (156 months-216 months at diagnosis)  Each age cohort sub-grouped by age at diagnosis, with random distribution between Capizzi and HD-MTX arms

Methotrexate Neurotoxicity Study  Areas of function assessed Global Intellectual function (IQ) Memory Attention Language (fluency, vocabulary) Planning and Organization Achievement (math and reading) Adaptive Behavior and Adjustment

Methotrexate Neurotoxicity Study  All children in the Younger Cohort will be evaluated with the same primary test (WISC-IV) at T3; the same applies to the Older Cohort (WAIS-III at T3)  The evaluation strategy for primary outcome is also applied to areas of specific function, so that cross age samples can be compared at the same time point using the same tests

Methotrexate Neurotoxicity Study Neurocognitive Outcomes Hypotheses  Hypothesis 1: Neurocognitive function at T3 will be significantly lower in children treated with HD-MTX than in children treated with LD-MTX.  Hypothesis 2: Neurocognitive function at T3 will be significantly lower in the Younger than Older Cohort, with a significant interaction between age at diagnosis and MTX exposure (HD vs. LD).  Hypothesis 3: Within the Younger Cohort (Age Groups 1, 2, & 3), younger age at diagnosis will result in lower neurocognitive function at T3 within both HD and LD MTX arms.  Hypothesis 4: Children in the Younger Cohort will have significantly lower scores on measures of specific function (memory, attention, language, processing speed, planning and organization, and achievement) than those in the Older Cohort.  Hypothesis 5: Age at diagnosis, MTX dose (HD vs LD), and the slope of neurocognitive function between T1 and T2, and neurocognitive function at T2 will be predictive of neurocognitive function at T3.

Concluding Points  Neurocognitive toxicity is no longer seen as a rare event. It is now a significant late effect. However, we don’t know to what degree this applies to treatment approaches outside that of the POG model of the 1990s. The opportunity to both prospectively model and compare different MTX approaches is unprecedented.  We hope that this new study will enable us to define the mechanisms of effect, leading to modifications in treatment, development of prevention strategies, or early identification for preventive behavioral or educational intervention