Comprehensive Haemato-Oncology Study Notes

Acute Myeloid Leukemia (AML) Fundamentals

• Epidemiology and Diagnosis

  • AML is the most common type of acute leukemia in adults.

  • In pediatric populations, $ALL$ is more common.

  • The median age of diagnosis is $65$ years.

  • Diagnosis requires more than $20\%$ blasts in the marrow.

  • Exceptions to the $20\%$ blast rule: A diagnosis can be made regardless of blast count in the presence of:

    • Translocation $8;21$ ($t(8;21)$).

    • Inversion $16$ ($inv(16)$) or translocation $16;16$.

    • These are referred to as CBF AML (Core Binding Factor AML).

    • Acute promyelocytic leukemia ($APML$).

• Morphology and Cytochemistry

  • AML blasts are classically large cells with a decent amount of cytoplasm.

  • Nuclei feature fine chromatin and prominent nucleoli.

  • A critical morphological finding is the presence of OR rods (Auer rods).

  • Staining reactions:

    • Myeloperoxidase ($MPO$) is the most common stain used.

    • Neuron specific enolase ($NSE$) or Suran black (Sudan Black) are also used.

• Clinical Features and Subtypes

  • Gum hypertrophy and myeloid sarcoma: These are more common in the $M4$ and $M5$ varieties.

  • Persistent hypokalemia: Often associated with the $M4$ subtype.

• Flow Cytometry Markers

  • Majority of cases express $CD34$ and $HLA\,DR$.

  • Myeloid markers: $CD117$, $CD13$, and $CD33$.

  • Monocyte markers: $CD11B$ and $CD14$ (seen in acute monocytic and myelomonocytic leukemia).

  • Acute megakaryocytic leukemia (Old FAB AML M7):

    • Often associated with myelofibrosis.

    • Significant markers include $CD41$ and $CD61$.

  • APML (Acute Promyelocytic Leukemia) Pattern:

    • Classically $HLA\,DR$ negative and $CD34$ negative.

    • $CD33$ is usually positive.

    • $CD2$ positivity can be seen in the hypogranular variant.

Risk Categorization and Cytogenetics in AML

• Risk Groups

  • Favorable Risk: Mutated $NPM1$ in the absence of $FLT3$; Translocation $8;21$ and Inversion $16$.

  • Intermediate Risk: The presence of any $FLT3$ mutation (mutated or wild-type $NPM1$) categorizes the patient as intermediate risk.

  • Poor Risk: Primarily associated with a complex karyotype, which carries the worst prognosis.

• Specific Translocations

  • t(8;21): Also known as $runx1-runx1\,T1$ (previously AML and ETO).

    • Most common cytogenetic abnormality in children with AML.

    • Associated with myeloid sarcoma.

    • Usually $HLA\,DR$, $CD34$, and $MPO$ positive, but shows weak expression of $CD3$.

    • Usually carries a good prognosis, but a $KIT$ mutation confers an adverse prognosis.

  • Inversion 16 / t(16;16):

    • Often features a monocytic component.

    • Classified as FAB $M4\,EO$ due to abnormal eosinophil components.

    • Common in younger patients; high incidence of myeloid sarcoma and CNS involvement.

    • Markers: $CD34$, $CD117$, $CD13$, $CD33$, $CD14$, and $CD64$.

Acute Promyelocytic Leukemia (APML/M3)

• Clinical Presentation and Genetics

  • Associated with translocation $15;17$ ($t(15;17)$) involving $PML-RARA$.

  • Presents with bleeding in unusual sites: spontaneous ecchymosis, profuse gum bleeding, pulmonary hemorrhage, or CNS hemorrhage.

  • Bleeding occurs even when platelet counts are relatively safe (e.g., $50,000-60,000$) due to spontaneous Disseminated Intravascular Coagulation (DIC).

  • White blood cell ($WBC$) count is usually not very high.

• Risk Stratification and Treatment

  • Risk is based on $WBC$ count: Lower/Intermediate risk ($WBC < 10,000$) vs. High Risk ($WBC > 10,000$).

  • Ultra-refractory translocations: $t(11;17)$ (specifically $PL\,ZF$) and $t(17;17)$.

  • Therapies and Toxicities:

    • UTTRA (ATRA): Can cause differentiation syndrome. Treatment involves steroids, specifically dexamethasone at $10\,mg/m^2$. Late complication: Pseudotumor cerebri (headache, blurry vision, papilledema).

    • Arsenic: Most important toxicity is $QT$ prolongation.

    • Relapse: Gemtuzumab vosocompromising (Gemtuzumab ozogamicin) is an option since cells are $CD33$ positive.

  • FLT3 in APML: Occurs in $20-30\%$ of cases but is not an independent prognostic factor and does not alter treatment (Midostaurin is not used).

Medical Management and Transplantation in AML

• Non-M3 Treatment (Medical Fit)

  • Standard regimen: "$3 + 7$" using Daunorubicin and $RSE$ (Cytarabine).

  • FLT3-positive patients: Add Midostaurin ($50\,mg$ twice daily) from day $8$ to $21$.

  • RATIFY Trial: Demonstrated superior median Overall Survival ($OS$) and Event-Free Survival ($EFS$) with Midostaurin with similar toxicity profiles.

• Transplant Indications

  • No transplant: Good risk in first remission.

  • Transplant in first remission: Intermediate risk (if match available) or High risk.

  • Other indications: Therapy-related or secondary AML, primary induction failure, second or subsequent remission/relapse, and elderly patients without other options.

• Management for Medically Unfit Patients

  • Venetoclax combined with a hypomethylating agent ($HMA$) or low-dose $RSE$ is the standard for unfit but not frail patients.

  • Targeted therapies: Use agents based on actionable mutations.

• Approved Therapies for Specific Indications

  • CPX-351: Liposomal encapsulation of cytarabine and daunorubicin (fixed $5:1$ ratio). Used for therapy-related AML.

  • Gemtuzumab govitecin: Targets $CD33$.

  • IDH inhibitors: Ivocedrin ($IDH1$) and s-adenine (Enasidenib for $IDH2$).

  • Glass digit (Glasdegib): Combined with low-dose $RSE$ for untreated AML.

  • Jiltered in an ease (Gilteritinib): For relapsed/refractory $FLT3$-positive AML.

  • New approvals (last year):

    • Pemigatinib for myeloid/lymphoid neoplasms with $FGFR1$ rearrangement.

    • Ivocedrin newly approved for newly diagnosed AML in combination with azacitidine.

Acute Lymphoblastic Leukemia (ALL)

• Diagnosis and Flow Cytometry

  • $MPO$ negativity suggests ALL; $TDT$ positivity is common but not mandatory.

  • Common B-ALL / CALA positive: $CD10$ positive.

  • Levels of differentiation: Pre-B, Pre-pro B, Pre-pre B, and Mature B (where surface immunoglobulin is present, resembling $L3$ morphology or Burkitt's leukemia).

• Cytogenetics and Prognosis

  • Good Prognosis: Hyperdiploidy; Translocation $12;21$ ($ETV6-RUNX1$), common in pediatrics ($1$ to $10$ years).

  • Poor Prognosis: Philadelphia chromosome (BCR-ABL1 positive); $KMT2A$ (MLL) rearrangement ($t(V;11)$), common in infantile ALL; Hypodiploidy; Translocation $1;19$; BCR-ABL1-like; iAMP21-like.

• Treatment and Toxicities

  • Induction includes steroids, Vincristine (side effects: ileus, neuropathy), Daunorubicin (mucositis, neutropenia).

  • L-asparaginase: Peculiar toxicities include anaphylaxis, $CVT$ (Cerebral Venous Thrombosis), hypoglycemia, encephalopathy, hepatotoxicity, hyperglycemia, and pancreatitis.

    • Clinical Pearl: If pancreatitis occurs, L-asparaginase must never be re-challenged.

• pH Positive ALL (Philadelphia Chromosome)

  • Features the minor BCR transcript ($p190$). Note: $p210$ is characteristic of CML.

  • Treatment: Imatinib ($400-800\,mg$), Dasatinib ($140\,mg$), or Ponatinib (for $T315I$ mutations).

  • Low-intensity chemo/steroids followed by allogeneic stem cell transplant if fit.

• Minimal Residual Disease (MRD)

  • Assessed by PCR, NGS, or flow cytometry.

  • MRD Negativity Threshold: Less than $0.01\%$ (which equals $10^{-4}$ malignant clones).

  • Clinical Implications: MRD positivity after day $28$ indicates poor prognosis and may necessitate treatment escalation or transplant.

  • Blinatumomab: A bispecific T-cell engager ($CD19/CD3$). Used in $CR1$ or $CR2$ with MRD $\ge 0.1\%$.

Mixed Phenotypic Acute Leukemia (MPAL) and BPDCN

• MPAL Criteria

  • Requires myeloid lineage ($MPO$ positive or monocytic differentiation) plus a lymphoid lineage.

  • T-cell lineage: Usually requires cytoplasmic $CD3$.

  • B-cell lineage: Strong $CD19$ with other markers, or weak $CD19$ with multiple markers.

• Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN)

  • Aggressive malignancy typically presenting in older men (e.g., $65$ years) with progressive cutaneous lesions, anemia, and thrombocytopenia.

  • Origin: Type II dendritic cells.

  • Markers: $CD45$ (low), $HLA\,DR$, and classically $CD123$.

  • Treatment: Tagaragsofusp (anti-$CD123$ cytotoxin).

Chronic Myeloid Leukemia (CML)

• Diagnosis and Monitoring

  • Defined by $BCR-ABL$ positivity. $2-4\%$ of cases have atypical transcripts requiring qualitative analysis for proper PCR monitoring.

  • Molecular Response Levels:

    • MMR / MR3: $< 0.1\%$.

    • MR4: $< 0.01\%$.

    • MR4.5: $\le 0.0032\%$.

    • MR5: Even lower levels.

• Response Assessment (Milestones at 3, 6, and 12 months)

  • Optimal Response: $3$ months ($< 10\%$), $6$ months ($< 1\%$), $12$ months ($\le 0.1\% / MMR$).

  • Failure: At $3$ months ($> 10\%$ if confirmed within $1-3$ months); any high-risk Additional Cytogenetic Abnormalities ($ACA$) or resistant mutations.

  • High-risk ACAs: Trisomy $8$ (most common), second Philadelphia chromosome, or isochromosome $17Q$.

• Treatment Free Remission (TFR)

  • Criteria to discontinue TKI: deep molecular response ($MR4$ for $3$ years or $MR4.5$ for $2$ years) and TKI therapy duration $> 5$ years.

• TKI Specific Toxicities

  • Dasatinib: Pleural effusion and pulmonary issues ($37-40\%$ of patients).

  • Nilotinib: Cardiovascular toxicities ($20\%$); Pancreatitis (if it occurs, Nilotinib cannot be reused).

  • Pregnancy: All TKIs are contraindicated in both 1st and 2nd trimesters. Dasatinib can cause hydrops fetalis. Men have no risk with TKIs at conception.

• Scoring Systems: ELTS and Sokal/Socal scores use age, spleen size, peripheral blast count, and platelet count.

Chronic Lymphocytic Leukemia (CLL)

• Diagnosis and Flow Cytometry

  • Requires absolute lymphocyte count $> 5,000$ per microliter sustained for $3$ months.

  • Markers: $CD5$, $CD23$, $CD200$ positive. $CD20$ is typically dim (requires higher Rituximab doses).

  • Monoclonal B-cell lymphocytosis ($MBL$): Same markers but count $< 5,000$.

• Staging Systems

  • Rai Staging: Stage 0 (Lymphocytosis); Stage 1 (Nodes); Stage 2 (Organomegaly); Stage 3 (Anemia); Stage 4 (Thrombocytopenia).

  • Binet Staging: A (limited nodes); B (high nodes/organomegaly); C (anemia/thrombocytopenia).

• Prognostic Factors

  • Aggressive: Unmutated $IGHV$, $ZAP-70$ ($> 20\%$), $CD38$ ($> 30\%$), $17p$ deletion, $11q$ deletion.

  • Indolent: Mutated $IGHV$, $13q$ deletion.

  • CLL-IPI: Factors include $17p$ deletion (highest points), unmutated $IGHV$, high beta-2 microglobulin, Rai stage $1-4$, and age $> 65$.

• Treatment Decisions

  • Treat only "active disease": marrow failure, symptomatic splenomegaly/adenopathy, progressive lymphocytosis, or B-symptoms (weight loss, fever, night sweats, and fatigue—fatigue is specific to CLL).

  • First-line: Acalabrutinib, Venetoclax + Obinutuzumab, or Ibrutinib.

  • FCR (Fludarabine, Cyclophosphamide, Rituximab): Used only for young patients ($< 65$) with mutated $IGHV$.

  • Specific Drug Notes:

    • Venetoclax: Anti-$BCL2$; requires gradual dose ramp-up ($20$ to $400\,mg$) due to Tumor Lysis Syndrome ($TLS$) risk.

    • Ibrutinib: BTK inhibitor; toxicity includes cytopenias, hypotension, and atrial fibrillation/flutter.

Hodgkin's Lymphoma (HL)

• Classification and Morphology

  • Origin: Mature B-cells. Reed-Sternberg ($RS$) cells usually lack $CD19/CD20$ but express $PAX5$.

  • Classical HL (CHL) Subtypes:

    • Nodular Sclerosis: Most common in the West.

    • Mixed Cellularity: Most common in India; associated with $EBV$.

    • Lymphocyte Rich: Rare; peripheral nodes.

    • Lymphocyte Depleted: Rarest.

  • NLPHL (Nodular Lymphocyte Predominant): Features "Popcorn cells" (LP cells), $CD45+$, $CD20+$, $BCL6$ rearranged. $CD15$ and $CD30$ are negative (unlike CHL).

• Evaluation and Staging

  • Deauville Score (PET imaging):

    • Score 1: No uptake.

    • Score 2: Uptake $<$ mediastinum.

    • Score 3: Uptake $>$ mediastinum but $<$ liver. (1-3 are considered negative).

    • Score 4: Uptake $>$ liver.

    • Score 5: Much higher than liver/new lesion.

  • IPS Scoring (Advanced HL): Age, hemoglobin, sex, albumin, stage, leukocytosis, and lymphopenia.

• Treatment Regimens

  • Standard: ABVD (Adriamycin, Bleomycin, Vinblastine, Dacarbazine).

  • RATHL Study: If PET negative after $2$ cycles, omit Bleomycin to reduce pulmonary toxicity.

  • Brentuximab Vedotin: Anti-$CD30$. Used with AVD (omit Bleomycin) in first line ($ECHELON-1$ trial) or in relapsed/maintenance settings.

Non-Hodgkin's Lymphoma (NHL) - Aggressive B-Cell

• Diffuse Large B-Cell Lymphoma (DLBCL)

  • Hans Algorithm (IHC-based): Differentiates GCB (Germinal Center B-cell) vs. non-GCB using $CD10$, $BCL6$, and $MUM1$.

    • If $CD10$ positive -> GCB.

    • If $CD10$ and $BCL6$ negative -> non-GCB.

  • Double Hit Lymphoma: Rearrangement of $CMYC$ and ($BCL2$ or $BCL6$) via FISH. GCB variety; very poor prognosis.

  • Double Expressor: Overexpression of $MYC$ and $BCL2$ proteins via IHC. Usually ABC (non-GCB) variety; poor, but better than double-hit.

  • Treatment: R-CHOP. For CNS disease, use High-dose Methotrexate.

  • Newer agents: Selinexor ($XPO1$ inhibitor), Tafasitamab (anti-$CD19$), Polatuzumab vedotin (antibody-drug conjugate).

  • CAR-T Therapy: Approved for second-line or later (anti-$CD19$).

Follicular and Low-Grade Lymphomas

• Follicular Lymphoma (FL)

  • Associated with $t(14;18)$ and $BCL2$ overexpression.

  • Grading based on centroblasts per high power field; Grade $3B$ (sheets of centroblasts) treated like DLBCL.

  • FLIPI criteria (N-O-L-A-S-H): Nodes ($> 4$), Old ($> 60$), LDH increased, Albumin (not in original), Stage ($III/IV$), Hemoglobin ($< 12$).

  • Treating FL: Indications include bulky mass ($> 7\,cm$), B-symptoms, splenomegaly, or cytopenias.

  • Splenic Marginal Zone Lymphoma: Associated with Hepatitis C; features villous lymphocytes; often requires only Rituximab.

Multiple Myeloma (MM)

• Pathophysiology

  • Most common subtype: $IgG\,kappa$.

  • Bone lesions: Osteolytic (activation of osteoclasts via RANKL, $IL-6$; inhibition of osteoblasts via $DKK1$). No $ALP$ elevation.

  • Morphology: Plasma cells feature an eccentric nucleus and a "perinuclear halo of Hof."

• Diagnosis and Staging

  • MGUS: M-protein $< 3\,g/dL$, marrow plasma cells $< 10\%$, no Myeloma Defining Events ($MDE$).

  • Active Myeloma (SLIM CRAB):

    • S: Sixty percent ($60\%$) plasma cells in marrow.

    • LI: Light chain ratio ($> 100$ or $< 0.01$).

    • M: MRI showing $> 1$ focal lesion.

    • CRAB: Calcium elevation, Renal insufficiency, Anemia, Bone lesions.

  • R-ISS Staging: Albumin, Beta-2 microglobulin, LDH, and high-risk cytogenetics ($t(4;14)$, $t(14;16)$, and $del(17p)$).

• Therapy and Toxicities

  • Bortezomib: Neuropathy, diarrhea, Zoster risk.

  • Carfilzomib: Cardiac toxicity.

  • Lenalidomide: DVT risk; skin issues; contraindicated in renal failure (use Thalidomide instead).

  • Melfaran: Used only for transplant conditioning (targets stem cells).

  • Belantamab Mafodotin: Anti-$BCMA$; causes corneal damage.

  • POEM Syndrome: Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein (usually Lambda), Skin changes. Major criteria include VEGF elevation and sclerotic bone lesions.

Stem Cell Transplant and MDS

• Transplant Principles

  • Conditioning: Myeloablative (High dose TBI/Busulfan) vs. Reduced Intensity (RIC) (lower doses, relies on GVL effect).

  • GVHD (Graft vs. Host Disease):

    • Targets skin, gut, and liver.

    • Prophylaxis: Tacrolimus/Methotrexate or Post-transplant Cyclophosphamide ($PTCY$) on days $+3$ and $+4$.

  • HLA Matching: $8$ out of $8$ match is preferred ($HLA-A, B, C, DRB1$). $KIR$ mismatch is often beneficial.

• Myelodysplastic Syndromes (MDS)

  • Therapy-related MDS: Type 1 (Alkylating agents, long latency, $del(5/7)$) vs. Type 2 (Topoisomerase II inhibitors, short latency, $11q/MLL$).

  • SF3B1 mutation: Most favorable mutation in MDS.

  • 5q- Syndrome: Specifically sensitive to Lenalidomide.

  • Luspatercept: Fusion protein used for ringed sideroblasts (inhibits TGF-beta pathway).