Myeloma and MGUS Flashcards
What are the key features of myeloma?
Monoclonal PCs
Paraprotein
(B) Osteolytic lesions (bone destruction)
(A) Anaemia
(R) Kidney failure
Infections/ immunosuppression
Angiogenesis
What does CRAN mean?
Calcaemia (hyper) >2.75
Renal failure Cr >177, eGFR<40
Anaemia Hb <100
N Bone pain 1+ lytic lesion
Multiple myeloma has very characteristic complications that arise from complex interactions with the tumour microenvironment (bone disease) or large-scale Ig secretion (renal failure)
What type of cells are in multiple myeloma?
Mature B cells which can make Ig
How is multiple myeloma linked to MGUS?
Transformation results from a range of numeric and structural genetic aberrations that accumulate from a pre-malignant condition (“MGUS”) to terminal progression
What is the second most common haematopoietic malignancy?
Multiple myeloma
What is the survival of multiple Myeloma?
4-7 years
Novel treatment approaches combined with “old-fashioned” chemotherapy are increasing survival rates
How do B cells mature?
- B cell encounters antigen and goes into germinal centre
- Affinity maturation: Somatic hypermutation and antigen selection
- Class switching to get correct isotype
- Plasmablast goes to bone marrow to produce antibodies
Where can mutations occur?
> Switching off cellular characteristics that are no longer required, such as cell cycling
> Activating programmes that are essential for antibody production
> Undergoing apoptosis if they do not find a receptive niche in the bone marrow
Failure to complete these programmes correctly could potentially leave active cellular processes, which may result in the features of myeloma.
What are key transcription factors in myeloma?
BCL-6, B cell lymphoma 6
BLIMP1, B lymphocyte-induced maturation protein 1
CIITA, MHC class II transactivator
ID3, DNA-binding protein inhibitor ID3
PAX5, paired box gene 5
XBP1, X box-binding protein 1.
Which cell secretes the most proteins?
Plasma Cells
What is the pathogenesis of multiple myeloma?
Insult to cell (infection/ inflammation)
MGUS
Microenvironment changes
Oncogenes and genetic changes etc.
Myeloma
What is the progression to Myeloma?
- MGUS (No CRAB)
- Smouldering Myeloma (No CRAB)
- Multiple Myeloma (CRAB)
- B Cell leukaemia
What would be seen in blood of MGUS?
Monoclonal serum protein < 30g/L
BM plasma cells < 10%
Annual risk of progression to MM 1-2%
Rare in young, increasing incidence with ag
What would be seen in blood of smouldering myeloma?
Monoclonal serum protein ≥ 30g/L
BM plasma cells ≥ 10%
Annual risk of progression to MM 10%
What is the epidemiology of myeloma?
o 4,500 new cases per year in the UK
o 15-20,000 people are living with myeloma in the UK [Incidence 5/100,000 per year]
o 15% of blood cancers and 1% of cancers
o 2x more frequent in blacks than in whites, less common in Asians
o Median age at diagnosis 65-70y -> median survival 3-4y (6-10y in patients fit for intensive treatment)
What investigations do you do for myeloma?
Electrophoresis Blood film Urine ESR BM aspirate
What would you find when investigating myeloma?
Electrophoresis: Dense ban of IgG/IgA monoclonal proteins Blood film: Rouleaux Urine: Bence Jones proteins ESR: High BM aspirate: >10% plasma cells
What is the aetiology of multiple myeloma?
Unsure
Chronic infection/ inflammation: RhA/ HHV8/ HIV - more chance for multiplication errors
What staging system is used for multiple myeloma?
Durie-Salmon staging system
Which mutations are linked to MGUS?
t(14q32) = 50%
del (Chr13) = 50%
Which mutations are linked to MM?
N-RAS, K-RAS = 30%
p16 methylation = 40%
2nd translocations = …
How can diagnostics be used in MGUS and MM?
Serum protein electrophoresis: Monoclonal gammopathy
Bone Marrow Aspirates: Large Golgi and ER (Immature cells = poor prognosis)
What is the difference between mature and immature cells?
o Mature plasmocytic myeloma cells = clumped chromatin, abundant cytoplasm, rare nucleoli
o Immature plasmoblastic myeloma cells = prominent nucleoli, reticular chromatin, less abundant cytoplasm
What would be positive/ negative in immunophenotyping?
o Positive: CD38 CD138 CD56/58 Monotypic cytoplasmic Ig Light Chain restriction (Kappa or Lambda positive)
o Negative:
CD19
CD20 (hence, Rituximab (targets CD20) cannot be used for B-cell depletion therapy)
Surface Ig
Summarise treatment in MM
o (1) “Classical” cytostatic drugs = melphalan (alkylating agents)
o (2) Proteasome inhibitors
o (3) “IMIDs” / Immunomodulatory Drugs = thalidomide, lenalidomide, pomalidomide
o (4) MoAbs / Monoclonal Antibodies = daratumumab
o Steroids
What do alkylating agents do?
o Adds alkyl ground to DNA -> crosslinks and blocks DNA replication -> lymphopenia
o Related compounds = cyclophosphamide, chlorambucil, ifosphamide
What is an autologous stem cell transplant?
§ (1) stem cells collected from blood and stored
§ (2) high dose melphalan used to kill myeloma cells
§ (3) re-infusion of stem cells to rescue blood formation
What do proteasome inhibitors do?
Causes proteins misfolded in ER to accumulate as proteasome cannot destroy them.
What is a proteasome?
Proteasome = large enzyme complex that degrades most intracellular proteins (i.e. damaged proteins) by ubiquinating (adding a functional group) and marking the protein for degradation
Prevents cell death by accumulation