# Presentation: 438969

## Childhood ALL

- Patrick Brown, MD
- JHH/NCI Fellowship Core Conference
- July 23, 2007

## Objectives

- What I will teach you today (the basics)
- Definition and classification
- Epidemiology, prognosis and etiology
- Clinical presentation (excluding oncologic emergencies)
- Diagnosis and differential diagnosis
- Risk stratification and treatment
- Late effects of treatment and follow-up
- The unique biology of “common ALL”

## What is leukemia?

- Derived from the Greek: *Leukos*  = white + *Haima*  = blood

_*Modern definition*_: cancer of the blood-forming cells in the bone marrow

## How is leukemia classified?

- Acute vs. Chronic (difference?)
- Lymphoid vs. Myeloid (ALL, CLL, AML, CML)

## Slide 5

## Slide 6

## Which type do kids usually get?

**<**

## Leukemia accounts for about 1/3 of childhood cancer

**How common is leukemia in kids?**

**SEER data**

## How common is leukemia in kids?

**How common is leukemia in kids?**

## Age and incidence

**Age and incidence**

**“****common ALL”**

## Age and incidence

**Age and incidence**

## How bad is ALL in kids?

**Years from diagnosis**

**Event-free Survival (%)**

**Risk-adapted therapy (90’s)**

**Intensive therapy (80’s)**

**CNS preventative therapy (70’s)**

**Combination **
**chemotherapy (60’s)**

**Single-agent**
**chemotherapy (50’s)**

## Age and prognosis in ALL

**Chessels, et al. Leukemia 1998. 12(4): 463-473**

## What about AML?

**What about AML?**

## What about AML?

**What about AML?**

**Overall Survival (%)**

## Hey, why did my kid get ALL?

- In vast majority of cases, we haven’t a clue
- Constitutional/heritable predispositions for leukemia
- Down syndrome
- 10 to 20-fold increased risk
- early age peak
- 60:40 ALL:AML (typically M7 preceded by TMD)
- biologically favorable subtypes, but increased toxicity with therapy (esp. anti-metabolites)
- mosaicism for +21 in PB/BM has similar implications

## Hey, why did my kid get ALL?

- Other (rare) heritable predispositions for leukemia

## Hey, why did my kid get ALL?

- Environmental exposures?
- Proven
- Ionizing radiation
- ALL peak after A-bomb 2-4 yrs (longer for AML)
- In utero exposure to dx rads
- Prior chemo (alkylators, epipodophyllotoxins – AML)
- Unproven
- EMF from power lines
- Topo II inhibitors – in utero exposure to foods (flavinoids, caffeine), other compounds (estrogen) with topo II inhibitory activity and infant MLL
- Infections (except EBV in endemic Burkitt’s)
- Polymorphisms/mutations in carcinogen detoxifying enzymes (GST, CYP, NQO1)

## How do kids present?

- Most symptoms and signs are caused by widespread infiltration by leukemia cells
- approx. 1012 (1 trillion) cells are in body at dx
- Replacement of normal bone marrow with leukemia cells
- Neutropenia – infection risk (total WBC may be low, high or nl)
- Anemia – fatigue, lethargy, headache, pallor, rarely CHF (careful with first transfusion)
- Thrombocytopenia – bleeding, bruising, petechiae

## How do kids present?

- Extramedullary organ infiltration

## How do kids present?

## What can kill ALL patients acutely?

- Infection
- Hyperleukocytosis
- Respiratory distress/SVC syndrome
- Tumor lysis syndrome

## How is diagnosis made?

- Peripheral blood morphology and flow (early!!!)
- Bone marrow aspiration/biopsy
- Morphology, Flow, Cytogenetics, FISH***
- J0002 (Leukemia Cell Bank), COG biology studies
- Biopsy: only if “dry tap” or assessment of cellularity needed (r/o SAA, e.g.)
- LP/IT chemo
- CSF for cytospin, cell count and diff
- CNS1: no blasts; CNS2: WBC<5, +blasts; CNS3: WBC>=5, +blasts
- Traumatic LP: negative impact on EFS, esp. for diagnostic LP (circulating blasts gain entry to CNS)
- Platelet count: keep > 100K if circulating blasts, can probably get away with >10K once peripheral blasts cleared

## Differential dx of leukemia?

- ITP
- Any suspected ITP case needs a careful PB smear review
- Other cancers which can metastasize to BM
- Neuroblastoma, rhabdomyosarcoma, retinoblastoma
- JRA
- Joint pain, fever, HSM, pallor common in both systemic onset JRA and leukemia – should do BMA prior to steroid use in suspected cases
- Aplastic anemia, MDS
- Requires BM biopsy (hypocellular)
- Infectious mononucleosis (EBV, esp.)
- Atypical lymphs can look a lot like ALL cells

## Classification: morphology

## Classification: flow

|  | CD19 | CD10 | cIg | sIg | % | Comment |
| --- | --- | --- | --- | --- | --- | --- |
| Pre-pre B | + | - | - | - | 5 | Infants and adolescents, poor px, MLL 11q23 common |
| Early pre-B | + | + | - | - | 63 | “Common ALL”, young kids, good px |
| Pre-B | + | + | + | - | 16 | Older kids, E2A-PBX1 t(1;19) common, good px w/intense rx |
| B | + | + | + | + | 4 | “Burkitt’s leukemia”, MYC/Ig fusion, good px with lymphoma rx |
| T | - | - | - | - | 12 | Adolescents, AMM, CNS, good px with intense rx, TCR fusions |

**Classification: flow**

## Classification: flow

- ALL immunophenotypes closely resemble normal stages of lymphocyte ontogeny

**pre-pre B**
**(5%)**

**early pre B**
**(60%)**

**pre B**
**(15%)**

**B-ALL**
**(3-4%)**

## Classification: molecular

- “Molecular” = recurrent, leukemia cell-specific abnormalities detected by cytogenetics, FISH***, and/or PCR
- Crucial (change treatment) – “The Big 5”
- TEL-AML1 fusion t(12;21)
- MLL fusions t(4;11) et al.
- BCR-ABL fusion t(9;22)
- “Triple Trisomy” +4, +10, +17
- Hypodiploidy < 44 chromosomes, or DNA index < 0.81

**Detectable by interphase FISH**

## Classification: molecular

- Helpful/interesting, but not crucial (don’t change treatment)
- E2A-PBX1 fusion t(1;19)
- Ig-MYC fusions t(8;14), t(8;22), t(2;8)
- TCR fusions (T-ALL) – with TAL1, HOX11, LYL1, LMO1/2
- Deregulated RAS signaling (RAS, SHP-2 mutations)
- FLT3 activating mutations – MLL, hyperdiploid
- Notch1 mutations – T-ALL
- Rb/p53 network alterations - p16, p14, p21 silencing/deletion

## How do we decide how to treat?

- Treatment is “risk-directed” and “diagnosis-specific”
- Patients at higher risk of relapse (based on past experience) get more intense (and toxic) treatment
- Definitions of risk groups and specific treatments differ by leukemic subtype
- AML vs. ALL
- ALL: pre-B vs. T vs. B
- Pre-B: infant vs. older kid

## Risk Stratification - ALL

- NCI-Rome risk criteria for ALL: WBC and age

- Smith, M et al. JCO 1996

## Risk Stratification - ALL

- Immunophenotype
- T- vs. B-lineage
- T-lineage often thought of as high risk, but similar outcomes with modern, intensive therapies  (likely not an independent risk factor)
- perhaps due to differences in purine metabolism – T-ALL needs higher MTX doses to overcome inherent resistance
- Burkitt’s – once a poor prognostic factor, now high cure rates with intensive, short duration chemotherapy

## Risk Stratification – pre-B ALL

- Ploidy
- Hyperdiploidy >50
- MTX transport, metabolism to polyglutamates (+21 copies)
- Specific trisomies (current: +4, +10 and +17)

- Harris *et al*, Blood 1992

## Risk Stratification – pre-B ALL

- Ploidy
- Hypodiploidy

- VHR on current
- COG protocol

- Heerema *et al*, Blood 1999

## Risk Stratification – pre-B ALL

- Specific molecular abnormalities
- BCR-ABL – Gleevec, BMT
- MLL – cytarabine/high hENT1 levels, BMT
- E2A-PBX – loss of prognostic importance with intensification
- TEL-AML1 – asparaginase sensitivity

- Pui *et al*, NEJM 2004

## Genetics and prognosis

**Genetics and prognosis**

**Q: Why do adults with ALL do worse than kids (40% vs. 80% survival)?**

**A: Biology**

## Risk Stratification – pre-B ALL

- Response-based
- Early response
- MRD (flow, molecular)

- Steinherz *et al*, JCO 1996

## Risk Stratification - ? future

- Gene expression signatures
- “destined to relapse” signatures
- “chemoresistance/sensitivity” signatures
- Pharmacogenomics – host interactions with therapy
- Thiopurine methyltransferase (TPMT)
- Glutathione S-transferase (GST)
- Thymidylate synthase (TS)
- Methylenetetrahydrofolate reductase (MTHFR)
- Cytochrome p450 isoenzymes

## How it “ALL” fits together

- Separate into therapeutically-relevant categories: pre-B (child vs. infant), T, B
- Risk stratify within category
- Treat
- On study: Randomize between best known therapy (standard arm) and best known therapy with some rational modification we hope will improve outcome (experimental arm)
- Off study: Treat with best known therapy (usually standard arm of most recently completed protocol)

## Generic components of ALL treatment

- Remission induction
-  (1 mo.)- Pred or Dex, Vcr, L-asp plus dauno in high risk ALL
- CNS preventative therapy
- IT chemo +/- XRT
- Consolidation (including IM - “interim maintenance” and DI - “delayed intensification” phase(s) in COG parlance)
- intensity and duration are risk-based, typically use alternating non-cross resistant drugs
- Maintenance
- oral 6-MP, MTX, pulses of VCR, steroids, IT MTX
- Duration: boys 3 yrs total, girls 2 years

## Slide 41

## Current COG risk stratification

**Suspected**
**ALL**
**(AALL03B1)**

**<=365 days**
**(AALL0631)**

**B-ALL**
**(ANHL01P1)**

**T-ALL**
**(AALL0434)**

**4-drug**
**induction**
**(P v. D, +dauno)**

**3-drug **
**Induction**
**(DVA)**

**NCI SR**

**NCI HR**

**SR-HIGH**

**SR-AVG**

**SR-LOW**

**Triple trisomy**
**    ****(4, 10, 17)**
**TEL-AML1 t(12;21)**
**D15 M1+MRD- (RER)**

**VHR**

**HR-HIGH**

**HR-AVG**

**CNS3, testicular,**
**    ****steroid pre-Rx**
**SER**
**MLL (RER)**

**D29 M3**
**Hypodip <44**
**BCR-ABL t(9;22)**
**MLL (SER)**

** ****D15 M1+MRD- (RER)**

**CNS3, testicular,**
**     ****steroid pre-Rx**
**SER**
**MLL (RER)**

** ****D15 M1+MRD- (RER)**

## Current COG risk stratification

**SR-HIGH**

**SR-AVG**

**SR-LOW**

**VHR**

**HR-HIGH**
**(SER)**

**HR-AVG**
**(RER)**

- No randomization; IC, double AIM/ADI

- 2 x 2 randomization: std vs. intense consolidation,
- std. vs. augmented single IM/DI

- Randomization: +/- PEG-Asp to std. consolidation, std IM/DI

- 2 x 2 randomization: dex vs. pred induction,
- Capizzi vs. HD MTX IM
- HR-AVG gets single IM/DI
- HR-HIGH gets double IM/DI

- No randomization; BMT for matched related donor available only;
- otherwise prolonged, intensive chemo
- Gleevec for Ph+

**0331**

**0232**

**0031**

## Relapsed ALL

**Gaynon, et al. Cancer 1998. 82(7): 1387-1395**

## Relapsed ALL

**Gaynon, et al. Cancer 1998. 82(7): 1387-1395**

## Relapsed ALL: Therapy

- Initiate stem cell donor search
- Attempt to reinduce remission (note that isolated CNS and testicular relapses also require intensive systemic therapy)
- BMT in CR (exception: consider chemotherapy only for late 1st relapses in no matched sib available)

## Slide 47

## Late Effects

- More long-term survivors
- CNS, psychosocial (XRT, IT Mtx)
- Endocrine and reproductive (XRT, IT Mtx, alkylators)
- Hypothyroidism, GH deficiency, central or primary gonadal failure
- Cardiac (cumulative anthracycline dose)
- Second neoplasms

## What do we worry about after cure?

## The Biology of “Common ALL”

**The Biology of “Common ALL”**

**“****common ALL”**

## The Biology of “Common ALL”

- CD10+, cIg- pre-B phenotype, TEL-AML1 or hyperdiploid genotype
- Risk period greatest in early childhood, then progressively decreases through adulthood
- Link to an infectious exposure?
- Timing of risk correlates with industrialization
- Toxic exposure?
- Risk is dependent on ethnicity
- Genetic influence?

## The Biology of “Common ALL”

- Contrasts sharply with AML
- Low risk through childhood, then massive and progressive increase with age after age 30
- Suggests a random, stochastic process in kids

- In adults, AML is caused by the accumulation of a lifetime’s worth of genetic insults (risk higher with smoking, certain industrial jobs, etc.) – similar to carcinomas

## A case...

- 3 y.o. girl presents with low grade fever, pallor, refusal to walk, and scattered bruises
- CBC:  1200>6.8/19.7<15K
- BMA
- Morphology:
- Flow: CD19+, CD10+, cIg-, sIg-
- Cytogenetics: t(12;21) -> TEL-AML1
- Diagnosis: early pre-B ALL (“common” ALL)
- Prognosis: excellent, >90% chance of cure
- “Why did my daughter get leukemia?”

## Childhood ALL starts in the womb

- Development of leukemia is a “multi-hit” process
- _Initiating/permissive mutation_ (1st hit)
- Occurs in utero or early infancy in ALL
- Peak of lymphocyte precursor recombinase activity, which generates the antigen-recognition “repertoire” through mutations in DNA
- Occasionally, recombinase makes an unwanted mutation, and a “pre-leukemic” lymphocyte precursor is created (and lies dormant, waiting....)

## The “first hit"

- Lymphocyte precursors are likely susceptible to leukemogenic mutations due to intrinsic mutagenic activity of the Ig VDJ and TCR recombinases, which are responsible for generating vast repertoire of antigen recognition sites

## The “second hit”

- _Promotional mutation_ (2nd hit)
- occurs when we need to generate tremendous numbers of mature, effector lymphocytes from a “pre-leukemic” lymphocyte precursor
- This usually happens in early childhood, which is when we are first exposed to exogenous antigens (viruses, allergens, toxins) that require us to mount an immune response

## Childhood ALL starts in the womb

- Evidence (Mel Greaves)
- Looked back at newborn screen cards of kids diagnosed with TEL-AML1+ ALL at various ages; found TEL-AML1 fusions in DNA extracted from blood spots
- Then looked at a bunch of unselected blood spots and cord blood samples, and found TEL-AML1 fusion in about 1%
- 1 in 100 babies have a pre-leukemic lymphocyte precursor
- BUT, only 1 in 30,000 get ALL
- SO, only 1 in 300 of TEL-AML1+ babies go on to get ALL (is this enough to justify screening?)

## The two “hits” of ALL

**The two “hits” of ALL**

**Leukemogenic**
**“****hit(s)”**

**#1**

**#2**

**1 in 100**

**1 in 300**

**Overall risk 1 in 30,000**

## Role of Detoxifying Enzyme SNPs?

**Role of Detoxifying Enzyme SNPs?**

## What about twins?

- Monozygotic concordance
- Index case < 1 yo, ~100% concordance, short latency
- intrauterine transfer
- most MLL (“single hit” oncogene or genomic instability)
- Index case 1-6 yo, ~20% concordance (most clonal), longer latency
- Prenatal preleukemic event (TEL-AML1, e.g), intrauterine transfer
- Relatively low risk of “second hit”
- Index case > 6 yo, slight increased risk
- No prenatal preleukemic event
- Dizygotic twins and sibs
- About 2-fold increased risk (but absolute risk still very low, so can reassure parents)

***Greaves, Blood 2003***

## How does this fit with AML?

**How does this fit with AML?**

**#1**

**#2**

**Overall risk 1 in 150,000**
**for kids vs. 1 in 6,000 for 75 y.o.**

**Risk of 1****st**** hit cumulative; 2****nd**** hit likely (constant proliferative stress for short-lived granulocytes)**