Blood Parameters in Treatment with Arsenic Trioxide in Acute Promyelocytic Leukemia: A Systematic Review

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML). APL is famed with some special blood coagulation disorders such as disseminated intravascular coagulation (DIC). The therapeutic methods of APL contain All Trans Retinoic Acid (ATRA), arsenic trioxide (ATO) or/and chemotherapy. Many studies have been done on APL blood disorders and its treatment. These studies have shown different results. In this systematic article, we tried to review the effect of ATO therapy with or without ATRA and chemotherapy on DIC parameters (D-dimer, Prothrombin Time, Activated Partial Thrombin Time, Platelet count) in APL patients. The result of included studies demonstrated that although ATO can reduce the number of malignant cells in the bone marrow and peripheral blood, it does not have enough potential to attenuate the danger of high score DIC that is usual in APL patients and should be better to be used with other therapeutic methods.


INTRODUCTION
Acute Myelocytic leukemia (AML) is the most common acute leukemia in adults 1 . The AML is classified into two categories. The first one is FAB that known as FRENCH-AMERICAN-BRITISH which is dividing AML into some characterized groups (AML-M0-AML-M7). The newest classification of AML belongs to WHO that classifies AML by mutations occurring in each class. Acute promyelocytic leukemia (APL) happens in 10-15% of AML incidence 2 . 98% of APL patients involve with the reciprocal and balanced translocation (15;17) (q22;q21)(PML-RARA) that include PML gene on chromosome 15 and RARA on chromosome 17. Acute promyelocytic leukemia is resulted by the halted myeloid precursors at the promyelocytic stage 3 . Morphology of peripheral blood smears (PBS) in APL blood samples indicates more than 20% blasts with promyelocytic dominance, and usually there are some inclusions in the cytoplasm of promyelocytes named Auer rods in bone marrow aspiration or peripheral blood sample 4 . In addition to these, APL has some other complications such as a high incidence of early hemorrhagic deaths 5 . 90% of APL patients have hemorrhage disorders 6 . A high rate of early death (about 30-60%) is due to the severe hemorrhagic disorders 7 . For that, the best way to save patients from more aggravate conditions or death is treating them as a medical emergency 5

Diagnosis of APL
If the patient is suspected for AML, the first stage is seeking the Peripheral Blood Smear (PBS) or bone marrow aspiration in order to calculate the blasts or promyelocytes percent. The AML is recognized when the count of blasts or precursors is 30% in FAB classification or 20% in the WHO classification of whole blood cells or bone marrow aspiration. For more confidence in the results, CD markers typing by flow cytometry, cytogenetic and karyotype method are appropriate to be done. CD markers which express on the APL cells include: CD33+, CD13+, CD34+, CD10+, ANTI-MPO+ and CD7-, CD79a-, CD117-, CD19-4 . In molecular genetics, the presence of t(15;17)( PML-RARA) hybrid gene is observed 12 .

Therapy
Early hemorrhagic deaths in APL mainly occur due to the severe thrombo-hemorrhagic coagulopathy 9 . Patients with severe thrombocytopenia (Platelet ≤20000/µl) should receive one/more platelet transfusions. Because of the coagulopathy disorders, the amount of fibrinogen decreases and on the other side, Prothrombin Time (PT) and Activated partial thromboplastin time (PTT) increase. Cryoprecipitate and FFP can increase the rate of fibrinogen and other coagulation factors 4 .

All-trans retinoic acid (ATRA)
This drug is a famous therapeutic method in APL patients. The mechanism of ATRA is the induction of progress in cell differentiation and converts promyelocytes to the Band/Neutrophils. Besides the induction of cell differentiation, ATRA decreases the expression of the TF factor and cancer procoagulant. Furthermore, ATRA has some more protective effects such as neutralizing cytokines effects, augmentation in thrombomodulin, a decrease in TF upregulation and endothelial cells maintenance 11 . Although ATRA controls the bleeding and this is a major advantage of this drug, thrombosis is a significant complication of ATRA 4,13 . Hung Chang et al. study claimed that delaying in APL treatment with ATRA causes severe hemorrhagic events in involved patients 4 . Lou Y et al. study demonstrated that delaying in the treatment with ATRA significantly increases the rate of mortality 13 . It is important to mention that the most common sites of hemorrhage in APL patients are lungs and brain 4,14 . The combination of ATRA and other anti-cancer therapies caused 90% of complete remission (CR) in APL patients. Although ATRA is the first step of therapy for the APL, this drug has some side effects. The side effects of ATRA are such as hypertension, cardiac failure, pericardial effusion or pleural effusion, headache and arthralgia 6 . ATRA as a single agent therapy has a 50-80% CR rate in APL patients 27 18 . The Mechanism of apoptosis induced by arsenic trioxide includes various types of mitochondrial damages which cause caspase activation and releasing cytochrome C (CYT-C) into the cytosol, so then it binds and activates APAF-1. Finally, CYT-C+APAF-1 complex activates procaspase-9. Caspase 9 cleaves procaspase 3, 6 and 7. This process prepares the cell for the internal apoptosis pathway 20 .

RESULTS
All patients in selected studies were involved with t(15;17)(PML-RARA) because the incidence of coagulopathies is higher in this subtype of leukemia. The studies in Tables 2-7 show the coagulation parameters before and after consuming the ATO, ATRA/chemotherapy. As mentioned in these studies, the parameters are in a high score, especially in D-dimer. The reduction of platelet (PLT) count demonstrates that they probably have been consumed in DIC or similar coagulopathy conditions. Jhang Y et al. study has demonstrated that the platelet count and fibrinogen levels in APL patients were low and inversely these patients had an evaluated rate in D-dimer, PT and APTT 21 . Other studies such as Hou J et al. and Xu F et al. acknowledged that the incidence of APL and its role in DIC happening caused early death in patients 22,7 , so that the treatment should be launched immediately to save or at least lessen the danger of DIC. In these studies, the treatment was done with All-trans-retinoic Acid (ATRA), Arsenic Trioxide (ATO) and/or chemotherapy 7,21-26 . Jhang Y et al. study illustrated that after the treatment on 103 patients, on day 0 to day 29, the APTT was in the normal range and the Fibrinogen in 10 days and PT test in 4 days came to normal range. After that, they concluded that ATO solely could not accelerate the recovery, but when it comes to ATRA+chemotherapy can alleviate the burden of the blood coagulation. They claimed that the recovery of APL patients for the DIC scores was due to the blood products injection 22  After then, 3 case study articles were checked in relation to our study. The first study included a 56-year old woman with APL. At first, she received ATRA + chemotherapy for 3 times and achieved complete remission, and then the therapy was continued with ATO 25 . The second case report included a 78-year old Hispanic man with some diseases such as type 2 diabetes mellitus, history of Alzheimer and hypertension because of the CML. Initially, he was under the Imatinib treatment and then Dasatinib. 7 years later, the result of complete blood count (CBC) showed abnormally elevated promyelocytes, and then characterized that besides t(9;22) for CML he had t(15;17)(PML-RARA), and his treatment started with ATRA/ATO. The last study included a 60-year old Japanese man with APL that he received ATRA and chemotherapy. But after 4

DISCUSSION
This study was on patients involved with acute promyelocytic leukemia. All patients had t(15;17)(PML;RARA).
The incidence of coagulopathies is higher in APL patients. Arsenic trioxide (ATO) is a toxic therapeutic method for cells. ATO often is used after ATRA and/or chemotherapy. The analysis of D-dimer parameter illustrated that 58.50% (n=306) (p <0.05) of cases were reduced after treatment. The analysis PT test showed that all cases (p <0.05) were decreased, but the PTT test was increased in 46.55% (n=142) of patients. The study of platelet count in 58.69% (n=307) (p <0.05) were recovered after treatment. APL treatment with ATO+ATRA has recovery effect on WBC and PLT count (Tables 6, 7). Many studies showed that treatment with ATO without ATRA and chemotherapy seems not to be sufficient for APL patients and it has some bad side effects 7, [21][22][23][24][25] . As results showed that the ATO does not have the potential to be used solely or at the frontline of the therapy procedure, it may be better to be prescribed with ATRA and chemotherapy or at least be used at the end-stage. The ATO treatment with or without ATRA or chemotherapy does not have a significant reduction effect on DIC parameters (D-dimer, PT and APTT) (Tables 3,4,5). ATO like other anticancer therapies has the potential to damage other cells because after using ATO, patients get in trouble with hypoplasia in the bone marrow and finally in peripheral blood, so because of these risky effects the physicians often prescribe ATO in a low dose.