In-hospital management of patients with thrombocytopenia caused by blood system diseases (2) - aplastic anemia

Author: Liu Jiajun, Department of Hematology, The Third Affiliated Hospital of Sun Yat-Sen
University
Aplastic anemia (AA) is a syndrome of bone marrow hematopoietic failure
.

The annual incidence rate in China is 0.
74/100,000 population, which can occur in all age groups
.

Congenital AA is rare, and the vast majority of AA are acquired.
The pathogenesis of AA is mainly believed to be bone marrow damage caused by abnormal activation and hyperfunction of T lymphocytes.
Genetic background may also play a role in the pathogenesis and progression of AA, such as telomerase.
Gene mutations, and somatic mutations are also found in some cases
.

AA can manifest as a low platelet count, and in thrombocytopenic diseases, AA is the main differential diagnosis
.

AA evaluation and process diagnostic criteria 1.
Blood routine examination: the whole blood cells (including reticulocytes) decreased, and the proportion of lymphocytes increased
.

At least two of the following three items: HGB<100g/L; PLT<50×109/L; Absolute neutrophil count (ANC)<1.
5×109/L
.

2.
Bone marrow aspiration: multiple sites (different planes) bone marrow hyperplasia decreased or severely decreased; small grains were empty, the proportion of non-hematopoietic cells (lymphocytes, reticulocytes, plasma cells, mast cells, etc.
) increased; megakaryocytes were significantly reduced or absent; Erythroid and granulocyte cells were significantly reduced
.

3.
Bone marrow biopsy (iliac bone): decreased hyperplasia of the whole section, decreased hematopoietic tissue, increased adipose tissue and (or) non-hematopoietic cells, no increase in reticulin, and no abnormal cells
.

4.
Exclusion check: Congenital and other acquired and secondary BMF must be excluded
.

Laboratory test items 1 required for the diagnosis of AA (1) Routine blood test: white blood cell count and classification, red blood cell count and morphology, hemoglobin (HGB) level, reticulocyte percentage and absolute value, platelet count (PLT) and morphology
.

(2) Multi-site bone marrow aspiration: including at least the ilium and the sternum
.

Bone marrow smear analysis: degree of proliferation of hematopoietic cells; morphology and stage percentage of granulocytes, erythrocytes and lymphoid cells; number and morphology of megakaryocytes; area of ​​small granulosa hematopoietic cells; whether there are abnormal cells,
etc.

(3) Bone marrow biopsy: at least 2 cm of bone marrow tissue (iliac bone) specimens are taken to evaluate the degree of bone marrow proliferation, the proportion of cells of each lineage, the distribution of hematopoietic tissue (with or without focal CD34+ cell distribution, etc.
), and whether there is bone marrow infiltration, bone marrow fibrosis,
etc.

(4) The number of CD34+ cells in bone marrow was detected by flow cytometry
.

(5) Liver, kidney, thyroid function, other biochemical, virology (including hepatitis virus, EBV, CMV, etc.
) and immunofixation electrophoresis examination
.

(6) Serum ferritin, folic acid and vitamin B12 levels
.

(7) Detection of paroxysmal nocturnal hemoglobinuria (PNH) clones (CD55, CD59, Flaer) by flow cytometry
.

(8) Detection of immune-related indicators: T cell subsets (such as CD4+, CD8+, Th1, Th2, Treg, etc.
) and cytokines (such as IFN-γ, IL-4, IL-10, etc.
), autoantibodies and rheumatic antibodies, Detection of related markers of hematopoietic stem cells and large granular lymphocytic leukemia
.

(9) Cytogenetics: routine karyotype analysis, fluorescence in situ hybridization [del(5q33), del(20q), etc.
] and genetic disease screening (chromosomal breakage test is recommended for children or those with family history), fetal hemoglobin detection
.

(10) Others: ECG, pulmonary function, abdominal ultrasound, echocardiography and other imaging tests (such as chest X-ray or CT, etc.
) to evaluate hematopoietic abnormalities caused by other reasons
.

2 Optional testing items Eligible hospitals can carry out the following items: (1) Bone marrow hematopoietic cell membrane autoantibody detection; (2) Telomere length and telomerase activity detection, telomerase gene mutation detection, and somatic gene mutation detection
.

Determination of the severity of the disease 1.
Diagnostic criteria for severe AA: (1) The degree of proliferation of bone marrow cells is <25% of normal; if ≥25% of normal but <50%, the residual hematopoietic cells should be <30%
.

(2) Blood routine: two of the following three items are required: ANC<0.
5×109/L; absolute value of reticulocytes<20×109/L; PLT<20×109/L
.

(3) If ANC<0.
2×109/L, it is extremely heavy AA
.

2.
Non-heavy AA diagnostic criteria: AA that does not meet the heavy criteria
.

In the treatment of AA, the indications for 1-component blood transfusion and red blood cell transfusion are generally HGB<60g/L
.

Red blood cell transfusion in old age (≥60 years old), low compensatory response ability (such as with heart and lung disease), increased oxygen demand (such as infection, fever, pain, etc.
), aggravated lack of oxygen supply (such as blood loss, pneumonia, etc.
) Indications can be relaxed to HGB≤80g/L), try to infuse red blood cell suspension
.

Irradiated or filtered red blood cell and platelet suspensions should be transfused for allogeneic hematopoietic stem cell transplant recipients
.

Those with risk factors for platelet consumption [infection, bleeding, antibiotics or antithymic/lymphocyte globulin (ATG/ALG), etc.
] or those with severe AA prophylactic platelet transfusion with PLT<20×109/L, and those with stable disease For PLT<10×109/L
.

Severe hemorrhage is not limited by the above criteria, and apheresis platelet concentrate suspension should be actively transfused
.

Ineffective transfusions due to the production of antiplatelet antibodies should be transfused with HLA-matched platelets
.

Granulocyte infusion therapy may be considered in agranulocytosis with uncontrolled bacterial and fungal infections that fail to respond to broad-spectrum antibiotics and antifungal therapy
.

The lifespan of granulocytes is only 6-8 hours, and continuous infusion for more than 3 days is recommended
.

During treatment, prevent and pay close attention to adverse reactions related to granulocyte transfusion, such as transfusion-related acute lung injury, allogeneic immune reactions, and febrile reactions
.

2 Other protective measures Severe AA patients should be protected and isolated, and those with conditions should be admitted to a laminar flow ward; avoid bleeding, prevent trauma and strenuous activities; necessary psychological care
.

Attention should be paid to dietary hygiene and preventive application of antifungal drugs
.

Prophylactic antibacterial, antiviral, and antifungal therapy are recommended for those who intend to undergo transplantation and ATG/ALG therapy
.

After hematopoietic stem cell transplantation, it is necessary to prevent Pneumocystis carinii infection, such as compound sulfamethoxazole (SMZco), but ATG/ALG treatment does not need to be routinely used
.

3.
Treatment of infection Fever in AA patients should be treated according to the treatment principle of "neutropenia with fever"
.

4.
Iron-repellent therapy For long-term repeated blood transfusions exceeding 20U and/or the serum ferritin level increased to the standard of iron overload, iron-repellent therapy can be given as appropriate
.

5 Vaccination There have been some reports suggesting that vaccination can lead to recurrence of BMF or AA, and vaccination is not advocated unless absolutely necessary
.

Treatment of this disease Once AA is diagnosed, it should be transferred to the Department of Hematology for specialist treatment
.

The severity of the disease should be determined before treatment, and treatment should be done as soon as possible
.

The standard therapy for severe AA is immunosuppressive therapy (IST) with ATG/ALG and cyclosporin A (CsA) for patients aged >35 years or aged ≤35 years without HLA-identical sibling donors; For severe AA patients aged ≤35 years with HLA-identical sibling donors, if there is no active infection and bleeding, HLA-identical sibling donors are the first choice for hematopoietic stem cell transplantation
.

Hematopoietic stem cell transplantation from HLA-matched unrelated donors is only used in young patients with severe AA who are refractory to ATG/ALG and CsA therapy
.

Bleeding and infection must be controlled before hematopoietic stem cell transplantation
.

Transfusion-dependent non-severe AA can be treated with CsA combined with hematopoietic (androgens, hematopoietic growth factors), and if the treatment fails for 6 months, it will be treated as severe AA
.

For non-transfusion-dependent non-severe AA, CsA and/or pro-hematopoietic therapy can be applied (Figure 1)
.

1 Immunosuppressive therapy (IST) ① ATG/ALG combined with cyclosporine A (CsA): suitable for severe or very severe AA patients without HLA-identical sibling donors; transfusion-dependent non-severe AA patients; CsA treatment for 6 months ineffective patients
.

②ATG/ALG: The dose of ATG/ALG from rabbits (produced in France and Germany) is 3~4 mg·kg-1·d-1, and the dose of ALG from pigs (produced in China) is 20~30 mg·kg-1·d-1 1
.

ATG/ALG needs to be used for 5 days, and intravenous infusion is performed daily for 12-18 hours
.

Before infusion, skin test and/or intravenous test should be performed according to the instructions of the corresponding drug preparation, and ATG/ALG treatment can be accepted only if the test is negative
.

Adrenal glucocorticoids should be administered concurrently with daily ATG/ALG to prevent allergic reactions
.

Acute-phase adverse reactions include hypersensitivity reactions, pyrexia, rigidity, rash, hypertension or hypotension, and fluid retention
.

Maintaining PLT>10×109/L during the treatment period may increase the need for platelet suspension transfusion due to the antiplatelet activity of ATG/ALG
.

Serum sickness reactions (arthralgia, myalgia, rash, mild proteinuria and thrombocytopenia) generally appear about 1 week after ATG/ALG treatment, so glucocorticoids should be used in sufficient doses for 15 days, and then reduced, usually 2 weeks After the reduction was completed (the total course of treatment was 4 weeks), patients with serum sickness were treated with intravenous adrenal glucocorticoid pulse therapy
.

For patients who failed the first ATG/ALG treatment or relapsed after two treatments, hematopoietic stem cell transplantation from HLA-matched unrelated donors or the second ATG/ALG treatment could be selected
.

Choose the second IST, and the interval should be 3-6 months from the previous treatment.
For the second course of ATG/ALG, it is advisable to use different ATG/ALG formulations derived from animal species as much as possible to reduce the occurrence of allergic reactions.
and risk of severe serum sickness
.

③CsA: When CsA combined with ATG/ALG is used for severe AA, the oral dose of CsA is 3~5 mg·kg-1·d-1, which can be used at the same time with ATG/ALG, or after glucocorticoids are discontinued, namely ATG/ALG Start 4 weeks after starting
.

CsA can be used for the treatment of non-severe AA
.

The exact effective blood drug concentration of CsA in the treatment of AA is not clear, the effective blood drug concentration window is large, and the general target blood drug concentration (trough concentration) is 100-200 μg/L for adults and 100-150 μg/L for children
.

Clinically, the dosage of CsA can be adjusted according to the drug concentration and efficacy
.

The main adverse reactions are digestive tract reaction, gingival hyperplasia, pigmentation, muscle tremor, liver and kidney function damage, headache and blood pressure changes in rare cases
.

Excessive dose reduction of CsA will increase the risk of recurrence.
Generally, it is recommended to gradually reduce the dose slowly, and continue taking the drug for at least 12 months after the efficacy reaches a plateau
.

Blood pressure, liver and kidney function should be monitored regularly during taking
.

④ Hematopoietic therapy: androgens can stimulate erythropoiesis in bone marrow and reduce excessive menstrual bleeding in female patients.
It is the basic hematopoietic drug for AA treatment
.

Compatible with CsA, it has certain curative effect in the treatment of non-severe AA
.

Stanozolol, testosterone undecanoate or danazol are generally used, and liver function should be checked regularly
.

It has also been reported that GM-CSF, G-CSF combined with immunosuppressive agents can promote hematopoiesis, or the addition of erythropoietin (EPO), recombinant human thrombopoietin (TPO) and interleukin 11 (IL-11) can also be used.
It is effective in the treatment of AA in combination with IST
.

Eltrombopag is a platelet receptor agonist approved by the US FDA for the treatment of refractory severe AA
.

Patients treated with ATG/ALG and CsA should be followed closely and checked regularly for timely evaluation of efficacy and adverse reactions (including the evolution of clonal diseases such as PNH, MDS and acute myeloid leukemia, etc.
)
.

The recommended follow-up observation points are 3 months, 6 months, 9 months, 1 year, 1.
5 years, 2 years, 2.
5 years, 3 years, 3.
5 years, 4 years, 5 years, and 10 years after ATG/ALG administration
.

2HLA-identical sibling donor hematopoietic stem cell transplantation is mainly suitable for severe or very severe AA patients aged ≤35 years old with HLA-identical sibling donors; severe AA patients over 35 years old, after ATG/ALG combined with CsA treatment fails
.

It is recommended to reinfuse mononuclear cells up to 3×108/kg body weight, and CD34+ cells at least 3×106/kg body weight
.

Bone marrow-containing grafts were used
.

For patients aged <30 years, the standard conditioning regimen is high-dose cyclophosphamide 50 mg·kg-1·d-1×4 d (-5~-2 d) and rabbit-derived ATG
.

The application of basic immunosuppressive agents such as CsA after transplantation is recommended to be slowly stopped after 1 year
.

3.
HLA-matched unrelated donors for hematopoietic stem cell transplantation must meet the following conditions at the same time: (1) a donor with complete HLA matching (class I antigen and class II antigen at the DNA level); (2) age <50 years old (between 50 and 60 years old, general condition Good); ③ patients with severe or very severe AA; ④ no HLA-matched sibling donors; ⑤ at least 1 ATG/ALG and CsA treatment failure; ⑥ no active infection and bleeding during hematopoietic stem cell transplantation
.

Conditioning regimen: Cyclophosphamide 300 mg·m-2·d-1×4 d is recommended for young patients; Fludarabine 30 mg·m-2·d-1×4 d; Rabbit ATG; CsA 1 mg· kg-1·d-1 (-6~-2d), 2 mg·kg-1·d-1 (-1~+20 d), and then changed to 8 mg·kg-1·d-1 orally; Bone marrow-containing grafts were used
.

The application of basic immunosuppressants such as CsA after transplantation is recommended to be slowly stopped after 1 year
.

4 Other immunosuppressants ① High-dose cyclophosphamide: Due to the high lethality and severe toxicity of high-dose cyclophosphamide (45 mg·kg-1·d-1×4 d), it is not recommended for hematopoietic stem cell transplantation without hematopoietic stem cell transplantation of newly diagnosed patients or AA patients who failed ATG/ALG combined CsA therapy
.

②Mycophenolate mofetil (MMF): The research on this drug is mainly focused on the treatment of refractory AA, but multiple center studies have shown that MMF is ineffective for refractory AA
.

③ Tacrolimus (FK506): It has the same signaling pathway as CsA to inhibit T cell activation, but has stronger effect, less nephrotoxicity, and no gingival hyperplasia, so it is used to replace CsA for the treatment of AA
.

④Rapamycin: It has a synergistic effect with CsA in suppressing T cell immunity, but the latest research shows that the addition of rapamycin on the basis of ATG/ALG combined with CsA cannot improve the treatment response rate of patients
.

Clinical studies of rapamycin combined with CsA in the treatment of refractory and relapsed AA are ongoing
.

⑤ Anti-CD52 monoclonal antibody: CD52 monoclonal antibody has been reported to treat recurrent SAA, but there is still a lack of large-scale clinical studies.
Currently, it is only recommended to be considered as a second-line regimen for the treatment of recurrent SAA
.

Efficacy evaluation 1.
Basic cure: anemia and bleeding symptoms disappeared, HGB reached 120g/L in males and 110g/L in females, ANC>1.
5×109/L, PLT>100×109/L, and no recurrence after follow-up for more than 1 year
.

2.
Remission: Anemia and bleeding symptoms disappeared, HGB reached 120g/L for males, 100g/L for females, WBC reached about 3.
5×109/L, PLT also increased to a certain extent, and the condition was stable or continued to progress after 3 months of follow-up
.

3.
Significant progress: anemia and bleeding symptoms improved significantly, no blood transfusion, HGB increased by more than 30 g/L compared with the common value within 1 month before treatment, and can be maintained for 3 months
.

To determine the above three efficacy standards, should not be blood transfusion within 3 months
.

4.
Ineffective: After adequate treatment, symptoms and blood routine did not improve significantly
.

Treatment of special circumstances 1 The treatment of hepatitis-related AA mostly occurs within 2 to 3 months after the onset of hepatitis
.

If there is a history of jaundice before the onset (usually 2 to 3 months before the onset), it may suggest hepatitis-related AA
.

Liver function tests are helpful for the detection of hepatitis-related AA
.

Hepatitis etiological tests for hepatitis-related AA may be negative
.

Should be tested for hepatitis A antibody, hepatitis B surface antigen, hepatitis C antibody and EBV
.

AA with hepatitis is generally more severe, has poor response to treatment, and has a poor prognosis
.

2 The treatment of IST in elderly AA is still the first choice, and some patients with syngeneic donors can consider hematopoietic stem cell transplantation
.

Although for non-severe AA patients, ATG combined with CsA is more effective than CsA alone, but for elderly patients, ATG treatment has greater toxicity and risk, so it still needs to be used with caution
.

Application of IST in elderly patients: There is no age limit for ATG in the treatment of AA, but comorbidities should be assessed before treatment in elderly patients with AA
.

When ATG/ALG treats elderly patients with AA, the risk of bleeding, infection and cardiovascular events is higher than that of younger patients.
Therefore, it is necessary to pay attention to the problems of cardiac function, liver function, blood lipids, and glucose tolerance in elderly patients
.

In view of the risk of nephrotoxicity and hypertension, it is recommended that the trough concentration of CsA in elderly patients with AA should be 100-150 μg/L
.

Other treatments include single-agent CsA, androgens, and alemtuzumab
.

Patients who cannot tolerate or refuse IST can be given supportive and symptomatic treatment such as traditional Chinese medicine
.

3 Treatment of patients with abnormal clonal AA A small number of AA patients have cytogenetic clonal abnormalities at the time of diagnosis, usually with +8, +6, and 13 chromosome abnormalities
.

Generally, abnormal clones only account for a small part of the total mitotic images, which may be transient and disappear on their own
.

Several studies have shown that AA patients with and without the aforementioned genetic abnormalities respond similarly to IST
.

AA patients with abnormal karyotypes should undergo bone marrow cytogenetic analysis every 3 to 6 months, and an increase in abnormal mitoses indicates disease transformation
.

4.
Treatment of AA patients with obvious PNH clones.
A small number of PNH clones can be detected in AA patients, and the patients have bone marrow cytopenias without hemolysis
.

Usually only monocytes and neutrophils are affected alone, and only a small fraction
.

Management of these patients is the same as for AA patients without PNH clones
.

ATG/ALG should be used with caution in patients with AA with significant PNH clones (>50%) and with clinical and biochemical markers of hemolysis
.

The treatment of patients with AA-PNH or PNH-AA syndrome is mainly PNH, taking into account AA
.

Long-term monitoring of PNH clones is recommended
.

5 Management of pregnant patients with AA AA can occur during pregnancy, and some patients require supportive care
.

After pregnancy in AA patients, the disease may progress
.

For pregnant AA patients, supportive treatment is mainly given, and platelet transfusion is used to maintain patients with PLT ≥ 20 × 109/L
.

The use of ATG/ALG during pregnancy is not recommended, and CsA can be used
.

Pregnancy status, blood routine and vital organ function should be closely monitored during pregnancy
.

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In-hospital management of patients with thrombocytopenia caused by blood system diseases (1) - Immune thrombocytopenia Click "read the original text", we will make progress together