1
Multiple myeloma
MUDr. Martin Štork, Ph.D.
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1. Introduction
(a) Importance and Direction of the Lesson
This lesson on the subject "Theoretical Basics of Clinical Medicine" will focus on hemato-oncology.
The goal of the lesson is to demonstrate comprehensive care for an oncology patient.
In this lesson, you will utilize knowledge of pathophysiology for differential diagnosis. You will also
gain initial experiences in managing common complications arising from oncology treatments and
familiarize yourself with the integration of the latest findings in tumor biology with modern diagnostic and
therapeutic approaches in hemato-oncology. The sample diagnosis for the lesson will be multiple
myeloma.
(b) Multiple myeloma
Multiple myeloma is the second most common malignancy of the hematopoietic system. It originates
from malignant plasma cells that cause organ damage to the affected individual through their activity.
Cells of multiple myeloma typically produce monoclonal immunoglobulin (paraprotein), which can be
detected in the patient's blood. Organ damage in multiple myeloma is known by the English acronym
CRAB (hyperCalcemia, Renal involvement, Anemia, Bone lesions).
The diagnosis of multiple myeloma relies on examining the bone marrow, confirming the presence
of clonal neoplastic plasma cells. In addition to routine tests (biochemical blood tests, complete blood
count, coagulation studies), whole-body imaging (CT, MRI, PET/CT) is performed to detect bone
lesions associated with this disease.
The treatment of multiple myeloma is predominantly pharmacological. Until recently, multiple
myeloma was considered an incurable disease. However, the current perspective on this condition
acknowledges the possibility of a cure in approximately 20% of patients with low-risk disease.
Structure of the lesson:
• Introduction
• Anemia – differential diagnosis
• Fever in immunocompromised patient
• Acute renal failure – differential diagnosis
• Monitoring of minimal residual disease and its significance
• Personalized Medicine in Hemato-Oncology
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2. Anaemia – differential diagnosis
(a) Introduction
Anaemia is precisely defined as a reduced amount of erythrocyte mass in blood. However,
determining this parameter is technically demanding, so in practice, we almost always rely on surrogate
parameters that correlate with erythrocyte mass – particularly haemoglobin concentration, red blood cell
count, or hematocrit. These values are less accurate because they depend on hydration status, but they
are usually sufficient to raise suspicion of anaemia and guide further investigation. Anaemia is
diagnosed when blood haemoglobin concentration reaches < 130 g/L in adult males or < 120 g/L in
adult non-pregnant females. The severity of anaemia is graded as follows: mild anaemia – normal to
110 g/L, moderate anaemia – 110 to 80 g/L, and severe anaemia – <80 g/L. In pregnant women,
especially in the later stages of pregnancy, these values are slightly lower due to their physiological
hypervolemia and relative dilution of blood.
(b) Causes of anaemia
Anaemia in some form affects about a quarter to a third of the world's population, making it one of
the most common chronic diseases overall – which means every medical doctor encounters it in
their clinical practice. Erythrocytes, like other blood cells, are produced in bone marrow. Differentiation
of hematopoietic stem cells into erythrocytes and their release into peripheral blood is primarily regulated
by erythropoietin, a hormone secreted by the kidney interstitium in response to hypoxemia.
Androgens also contribute to erythropoiesis, while estrogens have a slightly inhibitory effect (hence
lower haemoglobin reference ranges in women). Synthesis of haemoglobin, the dominant protein in
erythrocyte cytoplasm, is closely associated with erythrocyte maturation but also depends on other key
factors, particularly the availability of divalent iron, an essential component of the haemoglobin molecule.
Iron activates transcription factors that induce enzymes for heme and haemoglobin synthesis. Iron is
transported in the blood bound to transferrin, and its reservoirs include not only bone marrow but also
spleen and liver cells. Physiologically, erythrocyte production in the bone marrow is in a precisely
controlled equilibrium with their destruction in the spleen or liver after approximately 90 days of
circulation.
Although there are many steps in this complex process where dysfunction can occur, we can simplify
our considerations of the origin of anaemia into two major groups: anaemia due to decreased
erythrocyte production and anaemia due to erythrocyte loss or increased destruction. (Fig. 4.1)
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(a) Anaemia Due to Decreased Erythrocyte Production
Anemia due to decreased production is characterized by normal or decreased count of
reticulocytes which represent the penultimate stage of red cell development. The cause of these
anaemias lies either in the deficiency of erythroid lineage precursors or in disorders of their maturation.
The most common cause of such anaemia is iron deficiency (sideropenia). As mentioned
earlier, iron is critically important for haemoglobin synthesis and erythrocyte differentiation. Its deficiency
leads to anaemia with small erythrocytes (microcytes) that contain relatively little haemoglobin
(hypochromic anaemia). This condition can occur due to inadequate iron intake or malabsorption, as
well as chronic blood loss (e.g., gastrointestinal tract, urinary tract, gynaecological bleeding, etc.).
Iron is also an important growth factor for bacteria, so systemic inflammation leads to a decrease
in transferrin and thus in the availability of iron in blood plasma. Moreover, the cytokine hepcidin further
reduces the amount of iron released from stores. Therefore, erythrocytes in chronic inflammatory
conditions (chronic infection, neoplastic or autoimmune diseases) have a similar morphology to those
in absolute iron deficiency. This type of anaemia is called anaemia of chronic disease (ACD). The
same category also includes anaemia associated with kidney-damaging diseases (e.g., interstitial
nephritis) that result in decreased erythropoietin levels. Defective erythrocyte and haemoglobin
production in bone marrow may also be related to deficiencies of other substances necessary for proper
cell maturation in bone marrow. In particular, vitamins B9 (folic acid) and B12 (cobalamin) play a crucial
role in DNA synthesis. Folic acid deficiency is usually nutritional, while cobalamin deficiency can be
either nutritional (found only in animal products and fortified foods) or due to malabsorption in the
terminal ileum. The latter occurs for various reasons such as surgical resection of the intestine or
stomach or autoimmune destruction of the gastric parietal cells (i.e., atrophic gastritis), resulting in
decreased production of intrinsic factor, a protein necessary for B12 transport into the blood (pernicious
anaemia). Other factors contributing to malabsorption include chronic inflammation or certain
medications (proton pump inhibitors, metformin). The resulting anaemia is characterized by large
erythrocytes (megaloblasts), which are numerically deficient and partially undergo lysis in the bone
marrow.
Disorders of erythroid lineage division or maturation in bone marrow can be either congenital or
acquired. There are several predominantly monogenic diseases associated with erythropoiesis failure
or dysfunction, such as Fanconi anaemia or Diamond-Blackfan anaemia. However, acquired disorders,
such as myelodysplastic syndromes (MDS), or the effects of myelotoxic drugs (e.g., cytostatics), are
much more common. Another cause of anaemia may be the suppression of healthy hematopoiesis due
to the infiltration of bone marrow by malignant cells (leukaemia, multiple myeloma, lymphomas,
metastatic infiltration by solid tumours, etc.). These disorders are often accompanied by deficiencies in
other blood cell lineages.
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(b) Anaemia Due to Erythrocyte Loss or Increased Destruction
If hematopoiesis is unaffected, any loss of erythrocytes is followed by increased secretion of
erythropoietin due to systemic hypoxia. This leads to compensatory production of new erythrocytes,
which can be observed through an increased number of reticulocytes in the peripheral blood.
The most common cause of this type of anaemia is acute haemorrhage. Since bleeding results
in the loss of relatively equal amounts of erythrocytes and plasma, the immediate blood count (in
minutes) after bleeding may appear completely normal. The body's homeostatic mechanisms begin
compensating for the loss of blood volume by mobilizing extracellular fluid within hours. It takes a
significantly longer time to replenish the lost erythrocytes, resulting in relative anaemia.
Hemolytic anemias, that is anemias caused by erythrocyte destruction, can be classified into
corpuscular and extracorpuscular based on their pathophysiology. In corpuscular hemolytic anaemias,
the primary pathology lies within the erythrocyte itself, whereas in extracorpuscular hemolytic anaemias,
the pathology occurs outside of the erythrocyte. Corpuscular hemolytic anaemias are predominantly
congenital disorders. Among the causes are abnormal haemoglobin folding (sickle cell anaemia,
thalassemia, etc.), abnormal erythrocyte shape due to cytoskeletal disorders (hereditary
spherocytosis, elliptocytosis, etc.), or reduced resistance to oxidative stress which leads to
hemolysis upon exposure to triggering factors (e.g., favism). These diseases are not very common in
the European population.
Extracorpuscular hemolysis can be either immune or non-immune. The most common cause
of immune extracorpuscular hemolytic anaemia is the presence of antibodies against one's erythrocytes.
These antibodies are most commonly of the IgG class and cause erythrocyte destruction in the spleen
upon binding. IgM autoantibodies can cause complement fixation and hemolysis within the blood
vessels. Diagnosis of autoimmune hemolytic anaemia (AIHA) is confirmed by a direct antiglobulin test
(Coombs test). Non-immune extracorpuscular hemolytic anaemias are associated with mechanical
damage to erythrocytes (artificial heart valves, hemodialysis, extensive burns, microangiopathic
hemolytic anaemias, etc.), chemical agents (phospholipases in snake venom), or infectious causes
(malaria, sepsis).
Hemolysis can further be divided into extravascular and intravascular based on the site of
occurrence. Extravascular hemolysis occurs due to increased sequestration of erythrocytes by
reticuloendothelial cells, particularly splenic macrophages. Intravascular hemolysis takes place directly
within the blood vessels. The consequences of this process are more severe because the released
phospholipids from destroyed erythrocytes have strong thrombogenic effects, free haemoglobin is toxic
to renal tubular cells and heme tetrapyrroles can bind to free nitric oxide and cause generalized
vasospasms.
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During hemolysis, substances normally present in erythrocyte cytoplasm, such as lactate
dehydrogenase and free haemoglobin, appear in the patient's plasma. Haemoglobin is proteolytically
degraded, releasing free heme which is further metabolized to unconjugated bilirubin. A fraction of
free haemoglobin physiologically binds to a specialized plasma protein called haptoglobin, and this
complex is sequestered by the liver, leading to a decrease in circulating haptoglobin.
Fig 3.1. Anemia diagnostic algorithm
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3. Fever in immunocompromised patient
(a) Introduction
Immunocompromised patients have one of the components of immunity reduced
(cellular/humoral, specific/non-specific). Infections in these patients are often caused by opportunistic
pathogens (microorganisms with low virulence), these are more severe, rapidly progressing and tend
to persist. In patients with immunodeficiency, an early diagnosis of infection and immediate initiation
of appropriate treatment is very important. In these patients, fever is often the only sign of infection.
The most common groups of immunocompromised patients include diabetics, oncological patients,
critically ill patients (ICU), patients using immunosuppressive and biological treatment (rheumatology corticotherapy,
IBD), and patients after transplantation or splenectomy.
(b) Opportunistic pathogens
As opportunistic, we refer to those types of microbes that can cause infection only in people with
reduced defence mechanisms. In contrast, obligate pathogens can cause disease even in healthy
individuals. In case of bacterial infections, these are often infections originating from the patient's flora,
most often intestinal primarily symbiotic pathogens - E. coli, enterococcus spp., Klebsiella pneumoniae,
and anaerobes are less common. Pneumonia is usually caused by atypical microbes - viruses,
Mycoplasma pneumoniae, Pneumocystis carinii, and Legionella.
We can also encounter fungal infections in these patients, whether it is very common candidiasis,
or invasive mycosis occurring in patients with severe immunodeficiency, most often affecting the lung
parenchyma. Less often, we encounter fungal infections of the abdominal parenchymatous organs or
the central nervous system. These are most often caused by species of aspergillus, cryptococci or fungi
from the Mucor class - Cunninghamella echinulata, Mucor piriformis, and Absidia corymbifera.
Viral infections in severely immunocompromised patients are often caused by herpes viruses CMV
(pneumonia, colitis, optic nerve infection), generalized EBV, HSV or VZV infections. Obligate virus
infections often have an atypical course - severe pneumonia during influenza, SARS-CoV-2, and RSV.
Antivirals or, in the case of EBV, anti-CD20 antibodies (rituximab) are used in treatment.
i. Nosocomial infections
Infections arising in connection with hospitalization are referred to as nosocomial. These
infections can be exo- or endogenous, they are often respiratory or gastrointestinal infections, a
specific group is represented by catheter-related infection (CRBSI - catheter-related bloodstream
infection). These infections are often caused by strains of bacteria resistant to standard antibiotic
therapy.
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Enterococci resistant to vancomycin (VRE) or to the next line of therapy - linezolid (LRE) is
among the most important, for which the stock antibiotic tigecycline remains a therapeutic option. Other
frequently appearing strains are referred to as ESBL (extended-spectrum b-lactamase). These are
bacteria that hydrolyze most penicillins and cephalosporins. For these, carbapenems or highergeneration
cephalosporins can be used in therapy in combination with beta-lactam inhibitors (e.g.,
ceftazidime/avibactam). The next chapter is represented by Pseudomonas aeruginosa (PSAE)
infections, which are almost exclusively nosocomial. Due to its natural ability to produce a wide
range of proteolytic enzymes, this bacterium is primarily resistant to many commonly used
antibiotics, exceptionally in repeatedly hospitalized and ATB-treated patients we can encounter
carbapenem-resistant PSAE, with which our therapeutic options are severely limited.
The most effective prevention of the emergence of resistant strains of microbes in the hospital
environment remains rational antibiotic therapy - using ATB therapy only in highly suspected or
proven bacterial infections, taking materials for culture examinations before starting antibiotic
therapy (cultivation with verification of sensitivity enables a step-down from broad-spectrum ATB
therapy, which often leads to selection pressure on resistant strains). Furthermore, strict adherence to
the principles of asepsis and hand hygiene is necessary.
ii. Febrile neutropenia
Febrile neutropenia is a life-threatening condition. It is defined as a decrease in the number of
neutrophil granulocytes below 1.0 x 109
and the onset of fever above 38.0 °C and, at the same time,
no focus of infection was found (then the condition is referred to as infection of a specific organ in
neutropenia, e.g., pneumonia in neutropenia). This state presents one of the urgent conditions in
haematology, and with every hour of delay in the administration of ATB, mortality increases
exponentially. In the case of febrile neutropenia, it is necessary to search for the etiology of the
infection, to take at least blood for culture (hemoculture) and, if necessary, PCR examination before
starting antibiotic therapy, urine for culture and perform a basic imaging examination - X-ray of the heart
and lungs, paranasal sinuses, OPG, ultrasonography of abdomen and pelvis. In therapy, we use a
combination of broad-spectrum antibiotics and possibly also antifungals as mentioned further.
iii. Infection Prevention
To reduce the risk of infection, we try to isolate immunocompromised patients and we educate
patients about a suitable diet (exclusion of foods with a higher risk of fungal contamination).
Furthermore, in neutropenic patients, we apply granulocyte colony-stimulating factors (except for
myeloid malignancies, in which, in case of life-threatening infections, it is possible to use infusions of
donor granulocytes), in case of a drop in the level of IgG below 5 g/l, as a marker of specific humoral
immunity, we administer infusions of immunoglobulins. As part of pneumocystis pneumonia
prophylaxis, at-risk patients take cotrimoxazole 480 mg once a day. Fluconazole or posaconazole are
most often used to prevent fungal infections.
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(c) Therapy
The therapeutic procedure for febrile neutropenia is summarized in Figure 5.1.
Fig. 3.1 Therapeutic schema for febrile neutropenia
4. Acute renal failure – differential diagnosis
(a) Introduction
Acute renal failure is one of the most common issues encountered by internists. This diagnosis
encompasses a wide spectrum of causes yet leads to very similar metabolic consequences. Many
causes of acute renal failure can be reversible with prompt and appropriate treatment.
(b) Pathophysiology of Renal Failure and Basic Differential Diagnosis
i. Basic Classification
The classical model divides acute renal failure and its causes into prerenal, renal, and postrenal.
The prerenal part of the chain includes all processes and events that do not directly affect the renal
glomeruli or tubules. Disorders occurring at the glomerular membrane, within the urinary space between
the glomerulus and Bowman's capsule, in the renal tubules, or interstitium (excluding vascular flow
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disturbances) are classified as renal. Problems from the renal calyces to the end of the ureter are
referred to as postrenal.
ii. Prerenal Processes and Their Impairment
For proper kidney function, adequate perfusion is necessary. The incoming blood is filtered
through the glomerular membrane and oxygenates and nourishes the interstitium. Both filtration and
nourishment require sufficient perfusion pressure and blood volume flowing into the entire organ.
Both processes normally occur if the mean arterial pressure is at least 65mmHg (approximately
90mmHg systolic blood pressure). Autoregulatory mechanisms exist within the kidney between the two
circulations. When blood pressure or blood volume decreases, these mechanisms protect the renal
parenchyma from ischemia and hypoxia at the expense of reduced glomerular filtration and renal
clearance, which are fully reversible if decreased perfusion does not last too long.
In prerenal failure, the urine sediment is normal, proteinuria is absent, and a detailed urine
examination shows a fractional excretion of sodium (EF Na+) of less than 1%. Often, a reduced fluid
intake or increased fluid loss (sweating, diarrhoea, vomiting, diuretics) can be identified in the patient's
history, and signs of dehydration may be present during physical examination.
The treatment principle for prerenal failure is to restore kidney perfusion and oxygenation. In many
cases, hydration of the patient leading to volume replacement is sufficient. In more severe cases,
vasopressors may be required for hemodynamic stabilization. The causal treatment of the condition
leading to decreased perfusion (e.g., heart failure, bleeding, shock, fluid losses due to diarrhoea, etc.)
is essential. Mechanical obstruction of the renal artery is typically managed through surgical or
radiointerventional approaches.
iii. Renal Causes
Damage to the glomerulus can involve either the glomerular capillaries or the filtration membrane
itself. The result is similar in both cases - impaired glomerular filtration. The etiology can be diverse,
ranging from damage by microthrombi to inflammatory injuries (glomerulonephritis and vasculitis) or
amyloid infiltration. Damaged glomerular membranes can also allow bigger amounts of substances (and
substances normally unable to) to pass to and damage the renal tubules.
Damage of tubular cells can be related to direct toxic effects of substances (drugs, toxins) in the
primary urine or may result from precipitation and subsequent luminal obstruction by substances
that pass through the glomerular membrane (myoglobin, free light chains of immunoglobulins, urates,
oxalates, etc.). Tubular cells can also be damaged during prolonged prerenal failure, leading to their
hypoxia and necrosis. When renal tubules are damaged, the ability to concentrate urine and reabsorb
or excrete individual substances decreases, and this condition persists until the renal tubules are
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repaired. Clinically, this phenomenon is manifested by transitioning from oliguria to the polyuric phase
of acute renal failure, during which waste products remain elevated in the blood while the body produces
several litres of unconcentrated urine daily, leading to water and mineral losses.
When the interstitium is affected, similar consequences occur as with tubular damage. Transport of
substances between tubular cells and interstitial capillaries fails, and the osmotic gradient in the kidney
medulla is disrupted. Interstitial inflammation, vasculitis, amyloid deposition, and other conditions can
be considered as possible etiologies.
The renal cause may be suggested by the patient's medical history with symptoms of infection, use
of nephrotoxic medication, intoxication with nephrotoxic substances, or a known systemic disease
affecting the kidneys. Blood biochemical tests may show signs of inflammation, elevated uric acid,
and creatine kinase (a marker of rhabdomyolysis). Unlike prerenal failure, the urine sediment is never
normal in renal failure, and proteinuria, hematuria, squamous or cylindrical epithelial cells,
leukocyturia, and bacteriuria may be present in the urine. The fractional excretion of sodium (EF Na+)
is >1%. Renal ultrasound can exclude obstruction but may reveal damaged architecture of the kidney
parenchyma.
The treatment of renal failure consists of eliminating the underlying cause (discontinuing exposure to
nephrotoxic substances, managing autoimmune or infectious inflammation, treating systemic diseases,
etc.).
However, in many cases, the exact cause may not be initially known, or its removal may take some time.
In such cases, nonspecific therapeutic interventions play a significant role in preventing further
kidney damage. This nonspecific therapy primarily involves increased hydration and maintaining
adequate diuresis, potentially with the use of diuretics. In the polyuric phase, it is essential to adequately
replace ion and fluid losses.
If renal failure is severe, and its metabolic consequences are life-threatening, acute hemodialysis may
be necessary. Indications for acute hemodialysis include hyperkalemia (>6.5 mmol/l) or with EKG
changes, pH <7.2, hypervolemia, and fluid retention unresponsive to diuretics, or uremia >40 mmol/l or
earlier signs of uremic syndrome. The value of creatinine does not play a role in the decision for acute
hemodialysis.
iv. Postrenal Pathology
In postrenal renal failure, urine outflow is obstructed at any level from the renal calyces to the urethra.
Gradual pressure build-up within the bladder, ureters and calyces worsens the kidney's filtration ability,
and urine leakage into the interstitium leads to further restrictions in excretion and reabsorption. Due to
the large functional reserves of the kidneys, postrenal renal insufficiency becomes evident only when
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more than 50% of the renal parenchyma is compromised. For example, unilateral obstruction in one
kidney with an otherwise healthy second kidney may not show signs of renal failure.
Oliguria to anuria is present. In cases of obstruction at the level of the urinary bladder and below, a
palpable, painful distended urinary bladder may be observed. The definitive confirmation of the
diagnosis is through an ultrasound (UZV) examination, which demonstrates bilateral dilation of the
calyceal-pelvic systems. In most cases, the obstruction is mechanical. If the obstruction is close to
the kidneys, its cause may be visible on ultrasound; if not, further investigation using CT scans is
needed. The urine sediment may be normal but if the obstruction is intraluminal hematuria and epithelial
cells may be present. Stagnant urine provides an excellent substrate for bacteria, so leukocyturia and
bacteriuria may also be founnd.
The treatment of postrenal renal failure aims to restore urine flow. This form of treatment is often
achieved surgically (ureteral stenting, catheter placement in different parts of the urinary system).
Pharmacologically, it may involve influencing the obstruction, such as with benign prostatic hyperplasia
or neuromuscular dysfunction of the urinary bladder. In the case of postrenal failure, diuretics are
contraindicated as their use would worsen the existing situation.
Tab.6.1 Differential diagnostics of acute renal failure
Prerenal Renal Postrenal
● Dehydration
● Hypotension
● Shock
o Cardiogenic
o Hypovolemic
(including
hemorrhagic)
o Distribution
(anaphylaxis, sepsis,
SIRS)
o Obstructive
● Stenosis/thrombosis/embolis
m/extramural obstruction of
the renal artery
● Ischemic damage
● Nephrotoxic medication
● Intoxication by
nephrotoxic
compounds
● Urate nephropathy
● Rhabdomyolysis
(myoglobin)
● Microangiopathic
hemolytic anaemia
● Glomerulonephritis
● Vasculitis
● Systemic lupus
● Tubulointerstitial
nephritis
● Pyelonephritis
● Cast nephropathy
● Urethral
blockade
(foreign body,
tumour,
hematoma,
coagulum)
● Prostate
hyperplasia
● Obstructed urine
catheter
● Urinary bladder
tamponade
● Neuromuscular
impairment of
the urinary
bladder
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● Amyloid deposition
● Contrast-induced
nephropathy
● Renal tumours
● Renal trauma
● Bilateral ureteral
blockage
● Unilateral
ureteral
blockage with a
solitary kidney
5. Monitoring of minimal residual disease and its
significance
(a) Introduction
Minimal residual disease (MRD) is a small amount of cancer cells that persist in the patient's body
even after achieving disease remission. These cells are not detectable by conventional diagnostic
methods.
Biologically, MRD cells are an extremely interesting cell population. MRD cells can be resistant to
administered treatment, and therefore, they can regrow the cancer population and cause disease
relapse. On the other hand, there are cases of persistent stable MRD, suppressed by the patient's antitumor
immunity or by the effect of maintenance therapy. In some cases, the presence or absence of
MRD influences crucial treatment decisions for a specific patient.
(b) Methods of MRD Monitoring in Hematological Malignancies
By classical microscopic examination of bone marrow, 500 nuclear cells are evaluated. Although
microscopic examination still plays an indispensable role in the diagnosis of hematologic diseases, it is
not suitable for detecting MRD. This is due to the relatively small number of cells examined and the fact
that tumour cells sometimes have identical morphology to their physiological counterparts.
To detect MRD in a specific patient, we need to know the characteristics of tumour cells during
the initial diagnosis when there is an abundance of them in the bone marrow. Only then can we use
sensitive methods to capture the minimum number of tumour cells among the vast quantities of
physiological hematopoietic cells.
Flow cytometry is a highly effective method for MRD detection. The principle of flow cytometry
involves the passage of individual cells from the examined suspension through a narrow capillary. A
laser beam is directed at the individual cells in the capillary. The examined cell suspension is mixed with
a mixture of monoclonal antibodies targeting specific antigens on the cells. These monoclonal
antibodies are labelled with different fluorochromes that emit light of varying wavelengths when
illuminated by the laser beam. This emitted light is captured by the sensitive detectors of the instrument.
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Currently, by appropriately setting the laser and combining antibodies with fluorochromes, we can detect
up to 15 antigens in a single test tube within the cell population. Tumor cells have antigenic
characteristics that differ from physiological hematopoiesis. The appropriate combination of
antibodies and fluorochromes can detect tumour cells with a sensitivity of up to 10-6 (1 tumour cell in
1,000,000 healthy cells). However, we are not able to achieve such sensitivity for all hematologic
malignancies. The differences are determined by the antigenic distinctiveness of tumour cells from their
physiological counterparts.
Another suitable methodology for MRD detection is PCR (polymerase chain reaction) analysis. In
the examination of MRD in lymphoid malignancies, the detection of clonal rearrangements of
immunoglobulin heavy chains (IgH) or T-cell receptors (TCR) is often used. During lymphocyte
development, rearrangements occur in the VDJ segment of IgH and TCR. These rearrangements are
unique to each B or T lymphocyte clone, including those corresponding to the tumour population.
Another option is to monitor specific fusion genes (i.e., BCR-ABL, PML-RARA, ETV6-RUNX1, CBFBMYH11,
etc.) or mutations in typical genes for the patient's specific disease (i.e., NPM1). The absence
of these abnormalities in healthy hematopoiesis can be utilized for MRD detection.
(c) The significance of MRD monitoring in multiple myeloma
In the case of multiple myeloma, flow cytometry is used for MRD monitoring. Current protocols
achieve a detection limit of 10-6
for multiple myeloma. Due to its immense sensitivity and lower cost,
this method is preferred over PCR-based methods in the Czech Republic.
The absence of MRD in patients with multiple myeloma is a strong independent indicator of good
prognosis, although it does not guarantee a cure. Achieving MRD negativity is currently considered the
most significant therapeutic goal for patients with this disease.
(d) The significance of MRD monitoring in other hematologic malignancies
The significance of MRD varies for different hematologic malignancies. One of the most significant
analyses of MRD is in the case of acute lymphoblastic leukaemia of adult age. The persistence of
MRD after induction therapy is a clear indication for directing the patient towards allogeneic
hematopoietic cell transplantation. Allogeneic stem cell transplantation has the potential to eliminate
even chemo-resistant residual leukemic cells through the "graft-versus-leukemia" effect. A
comprehensive discussion of MRD in individual hematologic malignancies is the subject of ongoing
research and goes far beyond the scope of this chapter.
(e) New perspectives in the assessment of MRD in haematological
malignancies
The field of MRD assessment in haematology-oncology is relatively young. Soon, three main
directions of research need to be pursued.
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Firstly, it is necessary to link the MRD assessment results at specific stages of disease treatment
with specific changes in treatment strategies. For example, achieving MRD negativity at a certain
treatment phase should lead to the de-escalation of therapy without an increased risk of disease
progression (new activities). Conversely, in the case of MRD positivity, a precisely defined treatment
change should follow to achieve MRD negativity.
Secondly, the methodology for MRD assessment needs to be optimized to be more easily
applicable in routine laboratory practice. Currently, high-quality MRD analysis is predominantly
performed in highly specialized university laboratories.
Thirdly, there is a need to explore the use of new methods that are more sensitive and ideally
do not require invasive procedures (such as peripheral blood examination compared to bone marrow
examination).
6. Personalized Medicine in Hemato-Oncology
(a) Introduction
For decades, it has been known that different types of hematologic malignancies require distinct
treatment protocols. Furthermore, the population of patients who develop a specific histological type of
disease can significantly differ in terms of age, physical condition, and comorbidities. The current trend
in hemato-oncology is moving towards even greater personalization, which considers other factors, such
as molecular aspects of the pathogenesis of a specific disease in a particular patient.
(b) Tumor stage
One of the fundamental aspects of individualized patient treatment is the assessment of the extent
of the tumour using a staging system. This form of treatment individualization is particularly crucial in
solid tumour oncology. Staging in solid tumours is determined using the TNM classification (T = tumour
size and extent, N = lymph node involvement, M = presence of distant metastases). The size, anatomical
location, and absence of tumour metastasis determine the possibility of complete surgical resection,
leading to curative treatment. On the other hand, diseases to a greater extent require systemic anticancer
therapy.
Hematologic malignancies are, in most cases, disseminated diseases that require systemic
treatment. Staging is often expressed in terms of the degree of impact on healthy hematopoiesis
(e.g., Rai and Binet staging in chronic lymphocytic leukaemia) or the extent of organ damage (e.g.,
Durie-Salmon staging in multiple myeloma). In both mentioned cases, the disease stage is not the
determining factor for treatment but influences the prognosis of the disease. The anatomical extent of
the disease affects the intensity of treatment in malignant lymphomas. For example, localized stages
of certain lymphomas require less aggressive systemic treatment combined with localized radiation
therapy.
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(c) Tumor biology
In hemato-oncology, the severity of the disease is reflected more by specific prognostic
biomarkers. These often include the presence of recurrent genetic abnormalities or levels of certain
proteins in the blood.
In some cases, the presence or absence of these prognostic biomarkers leads to adjustments
in the treatment strategy. In multiple myeloma, for example, biomarkers such as beta-2 microglobulin,
albumin, lactate dehydrogenase, and high-risk cytogenetic abnormalities in malignant plasma cells
(del(17p13), t(4;14), and t(14;16)) are considered.
In other cases, the presence of certain biomarkers allows the use of targeted therapies that
directly affect the specific tumour clone in the patient. By targeting surface molecules detectable by
flow cytometry, monoclonal antibodies can be directed at the tumour clone. An example of this approach
is the treatment of acute lymphoblastic leukaemia with atypical CD20 antigen expression on leukemic
cells using the monoclonal antibody rituximab (anti-CD20).
Based on the presence of pathologically activated tyrosine kinases detected by PCR, targeted
inhibitors can be used. For example, about one-third of patients with acute myeloid leukaemia have
internal tandem duplications (ITDs) in the FLT3 tyrosine kinase. This mutation leads to autonomous and
sustained activation of the kinase, resulting in uncontrolled proliferation of leukemic blasts. After
detecting this mutation, the administration of a specific FLT3 inhibitor, such as midostaurin, is indicated
in addition to the standard treatment regimen. Another example is the treatment of acute lymphoblastic
leukaemia with atypical presence of the Philadelphia chromosome and the BCR-ABL fusion gene. These
patients are treated with tyrosine kinase inhibitors (imatinib, dasatinib) in addition to the standard acute
lymphoblastic leukaemia therapy.
The presence of other molecular targets, such as transcription factors, can also be therapeutically
influenced. The translocation t(15;17) with the PML-RARα fusion gene in patients with acute
promyelocytic leukaemia (APL). The formation of the PML-RARα fusion protein leads to a block in the
differentiation and maturation of leukemic promyelocytes. By using high doses of retinoic acid as
treatment, this block can be bypassed, resulting in the maturation of leukemic promyelocytes.
In patients with multiple myeloma and the t(11;14) translocation, there is overexpression of the antiapoptotic
protein BCL-2. These patients can be effectively treated with the BCL-2 inhibitor venetoclax.
(d) Patient`s performance status
It is always necessary to assess the overall condition of the patient, not just their age. Various
classification systems are used to assess the overall condition of oncology patients, with the most wellknown
being the Karnofsky Performance Status or the ECOG (Eastern Cooperative Oncology
Group) Performance Status. Both systems express how the tumour affects the patient's daily
activities (Table 9.1). A poor overall condition of the patient can be a limitation for oncological treatment,
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especially for aggressive treatment approaches such as intensive chemotherapy or hematopoietic stem
cell transplantation. However, if the overall condition is primarily influenced by the disease activity in an
otherwise healthy patient, it may not be an obstacle to aggressive treatment. Making decisions in these
cases requires considerable clinical experience from the treating oncologist and ideally involves
interdisciplinary team consensus.
(e) Comorbidities
When choosing oncology therapy, the typical side effects of anticancer drugs must be taken into
account concerning the patient's comorbidities (e.g., cardiotoxicity of anthracyclines in a patient with
heart failure, high doses of glucocorticoids in a diabetic patient, etc.). Another important aspect is the
pharmacokinetics of drugs in relation to comorbidities. For example, lenalidomide, one of the key
drugs in multiple myeloma, is predominantly eliminated by the kidneys. Impaired kidney function can
lead to the accumulation of lenalidomide in the blood plasma, resulting in its most common side effects
(leukopenia, anaemia, thrombocytopenia, seizures, and diarrhoea).
(f) Patient`s preference
The most important aspect when choosing oncology treatment is the decision of the well-informed
patient. After all, it is their health, and they should have the opportunity to feel a sense of shared
responsibility in the treatment process. In this case, it is crucial to explain to the patient the nature
of their illness and the chosen treatment. Furthermore, it is important to explain why the treatment
was chosen, how long it will last, what is expected from the patient, what possible complications may
arise, and if other alternatives exist. The common phrase, "I don't understand it, doctor, I'll leave it up
to you," should stimulate the physician to provide a more suitable form of explanation rather than
assuming absolute control over the patient's fate. The physician should inform the patient
sensitively but truthfully.
(g) New perspectives in personalized oncology treatment.
New perspectives lie in the detailed understanding of the oncogenesis process of individual
diseases and subsequently targeting this process through precision therapy. It may be a question of the
near future that we will not pay as much attention to the histological type of the tumour, but rather to the
deregulated signal pathway shared, for example, in breast, ovarian, or colon carcinoma. This approach
requires close collaboration between clinical oncology teams and molecular biology teams in so-called
"tumor boards."
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Tab. 9.1 - The performance status of the patient-scoring systems
Karnofsky performance status Karnofsky
- grade
ECOG -
score
ECOG performance status
Ability to perform normal activities without the need
for special care. Normal, without difficulties, and
signs of illness.
100 0 Fully active, able to engage in all
normal activities without limitations.
Ability to perform normal activities with mild signs or
symptoms of illness
90 1 Limitation in physically demanding
activities, ambulatory, able to
perform light work such as
household chores or office work.Ability to perform normal activities with increased
effort and presence of signs or symptoms of illness.
80
Unable to work, able to carry out normal daily
activities at home and take care of most personal
matters with varying degrees of assistance. Self-care
is possible, but unable to engage in normal activities
or work.
70 2 Ambulatory, able to take care of
oneself but unable to perform any
work, spending more than 50% of
the day out of bed.
Able to take care of the majority of their needs but
occasionally requires assistance
60
Requires significant assistance and frequent medical
care.
50 3 Capable of limited self-care,
bedridden for more than 50% of the
day.
Unable to care for oneself, requiring institutional care
or hospitalization, with the condition deteriorating
rapidly. Incapacitated and in need of specialized care
and assistance.
40
Severely incapacitated, hospitalization is indicated,
immediate death is not imminent
30 4 Completely incapacitated, unable to
care for oneself, bedridden or
confined to a chair.
Very ill, hospitalization is necessary, requiring
essential active supportive care.
20
Moribund; fatal processes progressing rapidly 10
Dead 0 5 Dead