All-trans retinoic acid at low concentration directly stimulates normal adult megakaryocytopoiesis in the presence of thrombopoietin or combined cytokines

All-trans retinoic acid added to treatment of primary immune thrombocytopenia: a systematic review and meta-analysis

All-trans retinoic acid (ATRA) application is a novel treatment approach for primary immune thrombocytopenia (ITP). This study aimed to evaluate the efficacy and safety of ATRA in the treatment of ITP. The databases of PubMed (MEDLINE), EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and China National Knowledge Internet were searched on August 5, 2022, to find randomized controlled trials (RCTs) and observational studies. Five observational studies and four RCTs from China were included, and 760 Chinese patients were analyzed. In the five observational studies, the pooled overall response rate (ORR) and complete response rate (CRR) were 59.5% (95% confidence interval [CI], 52.4-66.4%) and 20.6% (95% CI, 14.3-27.6%), respectively. In the selected four RCTs, the pooled odds ratios for sustained response rate, ORR, and CRR were 3.00 (95% CI, 1.97-4.57; P < 0.01), 3.21 (95% CI, 2.15-4.78; P < 0.01), and 2.12 (95% CI, 1.17-3.86; P = 0.01), respectively. ATRA was associated with a reduction in relapse rate and salvage treatment rate (odds ratio, 0.30; 95% CI, 0.18-0.50; P < 0.01; 0.36; 95% CI, 0.23-0.56; P < 0.01, respectively). The pooled odds ratios for grade 1-2 dry skin, headache (or dizziness), and rash acneiform were 49.99 (95% CI, 16.05-155.67; P < 0.01), 1.75 (95% CI, 0.98-3.12; P = 0.06), and 0.37 (95% CI, 0.10-1.34; P = 0.13), respectively. This study suggests that ATRA may significantly improve the initial and long-term response of patients with ITP.

Application and investigation of thrombopoiesis-stimulating agents in the treatment of thrombocytopenia

Platelets, derived from a certain subpopulation of megakaryocytes, are closely related to hemostasis, coagulation, metastasis, inflammation, and cancer progression. Thrombopoiesis is a dynamic process regulated by various signaling pathways in which thrombopoietin (THPO)-MPL is dominant. Thrombopoiesis-stimulating agents could promote platelet production, showing therapeutic effects in different kinds of thrombocytopenia. Some thrombopoiesis-stimulating agents are currently used in clinical practices to treat thrombocytopenia. The others are not in clinical investigations to deal with thrombocytopenia but have potential in thrombopoiesis. Their potential values in thrombocytopenia treatment should be highly regarded. Novel drug screening models and drug repurposing research have found many new agents and yielded promising outcomes in preclinical or clinical studies. This review will briefly introduce thrombopoiesis-stimulating agents currently or potentially valuable in thrombocytopenia treatment and summarize the possible mechanisms and therapeutic effects, which may enrich the pharmacological armamentarium for the medical treatment of thrombocytopenia.

A Review and Assessment of Drug-Induced Thrombocytosis

OBJECTIVES

The purpose of this article is to review the current literature on drug-induced thrombocytosis with the goal of critically assessing causality and providing a comprehensive review of the topic. Thrombopoietic growth factors, such as thrombopoietin-receptor agonists (romiplostim and eltrombopag) and erythropoietin are not included in our review.

DATA SOURCES

The literature search included published articles limited to the English language and humans in MEDLINE, EMBASE, and Web of Science databases. MEDLINE/PubMed (1966 to September 2018) was searched using the MeSH terms thrombocytosis/chemically-induced and thrombocytosis/etiology. EMBASE (1980 to September 2018) was searched using the EMTAGS thrombocytosis/side effect. Web of Science (1970 to September 2018) was searched using the search term thrombocytosis. References of all relevant articles were reviewed for additional citations and information.

STUDY SELECTION AND DATA EXTRACTION

Review articles, clinical trials, background data, case series, and case reports of drug-induced thrombocytosis were collected, and case reports were assessed for causality using a modified Naranjo nomogram.

DATA SYNTHESIS

Drug-induced thrombocytosis, a form of reactive thrombocytosis cannot be easily differentiated from more common etiologies of reactive thrombocytosis. In all, 43 case reports of drug-induced thrombocytosis from a wide variety of drugs and drug classes were reviewed using a modified Naranjo probability scale that included criteria specific for thrombocytosis.

CONCLUSIONS

Drug-induced thrombocytosis is a relatively rare adverse drug reaction. The strongest evidence of causality supports low-molecular-weight heparins and neonatal drug withdrawal. Weaker evidence exists for all-trans retinoic acid, antibiotics, clozapine, epinephrine, gemcitabine, and vinca alkaloids.

Oral all-trans retinoic acid plus danazol versus danazol as second-line treatment in adults with primary immune thrombocytopenia: a multicentre, randomised, open-label, phase 2 trial

BACKGROUND

Primary immune thrombocytopenia is a severe bleeding disorder. About 50-85% of patients achieve initial remission from first-line therapies, but optimal second-line treatment remains a challenge. All-trans retinoic acid (ATRA) has an immunomodulatory effect on haemopoiesis, making it a possible treatment option. We aimed to evaluate the efficacy and safety of ATRA plus danazol versus danazol in non-splenectomised patients with corticosteroid-resistant or relapsed primary immune thrombocytopenia.

METHODS

We did a multicentre, randomised, open-label, phase 2 study of adult patients (≥18 years) with primary immune thrombocytopenia from five different tertiary medical centres in China. Those eligible were non-splenectomised, resistant to corticosteroid treatment or relapsed, and had a platelet count less than 30 × 10⁹ per L. Masked statisticians used simple randomisation to assign patients (1:1) to receive oral ATRA (10 mg twice daily) plus oral danazol (200 mg twice daily) or oral danazol monotherapy (200 mg twice daily) for 16 weeks. Neither clinicians nor patients were masked to group assignments. All patients were assessed every week during the first 8 weeks of treatment, and at 2-week intervals thereafter. The primary endpoint was 12-month sustained response defined as platelet count of 30 × 10⁹ per L or more and at least a doubling of baseline platelet count (partial response), or a platelet count of 100 × 10⁹ per L or more (complete response) and the absence of bleeding without rescue medication at the 12-month follow-up. All randomly allocated patients, except for those who withdrew consent, were included in the modified intention-to-treat population and efficacy assessment, and all patients who received at least one dose of the study agents were included in the safety analysis. Study enrolment was stopped early because the trial results crossed the interim analysis efficacy boundary for sustained response. This trial is registered with ClinicalTrials.gov, number NCT01667263.

FINDINGS

From June 1, 2012, to July 1, 2016, we screened 130 patients for eligibility; 34 were excluded and 96 were randomly assigned. 93 patients were included in the modified intention-to-treat analysis: 45 in the ATRA plus danazol group and 48 in the danazol group. At the 12-month follow-up, sustained response was achieved more frequently in patients receiving ATRA plus danazol than in those receiving danazol monotherapy (28 [62%] of 45 vs 12 [25%] of 48; odds ratio 4·94, 95% CI 2·03-12·02, p=0·00037). Only two grade 3 adverse events were reported: one (2%) patient receiving ATRA plus danazol with dry skin, and one (2%) patient receiving danazol monotherapy with liver injury. There was no grade 4 or worse adverse event or treatment-related death in either group.

INTERPRETATION

Patients with primary immune thrombocytopenia given ATRA plus danazol had a rapid and sustained response compared with danazol monotherapy. This finding suggests that ATRA represents a promising candidate for patients with corticosteroid-resistant or relapsed primary immune thrombocytopenia.

FUNDING

National Natural Science Foundation of China, Beijing Natural Science Foundation, Beijing Municipal Science and Technology Commission, and the National Key Research and Development Program of China.

Leukemia Cells and the Cytokine Network: Therapeutic Prospects

The network and balance of cytokines is of major importance in maintaining proper homeostasis of hematopoiesis. Abnormalities in this network may result in a variety of blood disorders; however, the role of this network is not clear in leukemia. The use of antineoplastic agents has improved the survival rate of some types of leukemia, and adjunctive therapy with cytokines may be helpful. Chemotherapeutic approaches are no longer the best choice because cytotoxicity may affect normal and leukemic cells, and leukemic cells may develop resistance to the chemotherapeutic agent. Induction of differentiation to a mature phenotype and the control of apoptotic-gene expression have provided other possible alternative therapies. Combined effects of cytokines and vitamin derivatives such as retinoic acid (RA) and 1, 25 dihydroxyvitamin D3 (VD3) were found more beneficial than any of these agents individually. These agents exhibit cooperative effects, potentiate each other's effects, or both. Therefore, understanding the hematopoietic actions of these agents, their interactions with their receptors, and their differentiation signaling pathways may result In the design of new therapies. However, the role of cytokines in apoptosis is controversial because in some cases they were found to increase tumor cell resistance to apoptosis-inducing agents. Recent studies in the molecular biology of gene regulation, transcription factors, and repressors have led to new possible approaches such as differentiation therapy for the treatment of leukemia. In addition, the development of drugs that act on the molecular level such as imatinib is just the beginning of a new era in molecular targeted therapy in which the drug acts specifically on the leukemic cell. There are many possible combinations of cytokines, retinoids, and VD3, and perhaps the best therapeutic combination is yet to be described. This minireview is an update on the role of cytokines and the therapeutic potential of combinations with agents such as RA, VD3, and other chemotherapeutic agents.

Integrated Biophysical and Biochemical Signals Augment Megakaryopoiesis and Thrombopoiesis in a Three-Dimensional Rotary Culture System

Platelet transfusion has been widely used in patients undergoing chemotherapy or radiotherapy; however, the shortage of the platelet supply limits the care of patients. Although derivation of clinical-scale platelets in vitro could provide a new source for transfusion, the devices and procedures for deriving scalable platelets for clinical applications have not been established. In the present study, we found that a rotary cell culture system (RCCS) can potentiate megakaryopoiesis and significantly improve the efficiency of platelet generation. When used with chemical compounds and growth factors identified via small-scale screening, the RCCS improved platelet generation efficiency by as much as ∼3.7-fold compared with static conditions. Shear force, simulated microgravity, and better diffusion of nutrients and oxygen from the RCCS, altogether, might account for the improved efficient platelet generation. The cost-effective and highly controllable strategy and methodology represent an important step toward large-scale platelet production for future biomedical and clinical applications. Significance: Platelet transfusion has been widely used in patients undergoing chemotherapy or radiotherapy; however, the shortage of platelet supply limits the care of patients. Thus, derivation of clinical-scale platelets in vitro would provide a new source for transfusion. The present study evaluated a rotary suspension cell culture system that was able to potentiate megakaryopoiesis and significantly improved the efficiency of platelet generation. When used with chemical compounds and growth factors identified via small-scale screening, the three-dimensional system improved platelet generation efficiency compared with the static condition. The three-dimensional device and the strategy developed in the present study should markedly improve the generation of large-scale platelets for use in future biomedical and clinical settings.

Integrated Biophysical and Biochemical Signals Augment Megakaryopoiesis and Thrombopoiesis in a Three-Dimensional Rotary Culture System

Significance

Platelet transfusion has been widely used in patients undergoing chemotherapy or radiotherapy; however, the shortage of platelet supply limits the care of patients. Thus, derivation of clinical-scale platelets in vitro would provide a new source for transfusion. The present study evaluated a rotary suspension cell culture system that was able to potentiate megakaryopoiesis and significantly improved the efficiency of platelet generation. When used with chemical compounds and growth factors identified via small-scale screening, the three-dimensional system improved platelet generation efficiency compared with the static condition. The three-dimensional device and the strategy developed in the present study should markedly improve the generation of large-scale platelets for use in future biomedical and clinical settings.

All-trans retinoic acid directly up-regulates thrombopoietin transcription in human bone marrow stromal cells

OBJECTIVE

All-trans retinoic acid (ATRA) has been used as the first-line therapy for patients with acute promyelocytic leukemia (APL). We previously reported that ATRA increased serum thrombopoietin (TPO) levels accompanied by thrombocytosis during ATRA therapy for APL. In this study, we investigated the mechanism of transcriptional regulation of TPO gene by ATRA using human bone marrow stromal cells.

PATIENTS AND METHODS

Real time reverse transcriptase polymerase chain reaction and Western blotting were performed to quantify TPO mRNA and protein levels in cells from the human bone marrow stromal cell line KM101. Luciferase-based reporter assay, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP) assay were performed to identify a retinoic acid responsive element in the promoter region of TPO gene (TPO-RARE).

RESULTS

TPO mRNA expression was up-regulated by approximately 2.9 times 8 hours after stimulation with 10(-6) M ATRA in KM101 cells. In contrast, ATRA did not alter TPO mRNA expression in cells from the human hepatoma cell line HepG2. Protein level of KM101 cells also was increased with 10(-6) M ATRA for 48 hours in KM101 cells. We found the synthesized RARalpha protein bound to [gamma-32P]-labeled TPO-RARE probe and its binding was competed by adding 200x amount of cold TPO-RARE probe by EMSA. In addition, [gamma-32P]-labeled TPO-RARE probe bound to KM101 nuclear protein extract was supershifted by anti-RARalpha antibody and modified by treatment with ATRA. The relative luciferase activity of TPO gene was increased by 2.2x and the histone H4 was acetylated through TPO-RARE after ATRA stimulation in KM101 cells by ChIP assay.

CONCLUSION

These data support the direct up-regulation of TPO transcription by ATRA stimulation in human bone marrow stromal cells and propose one of the mechanisms of thrombocytosis during ATRA therapy for APL.

Hematopoietic, angiogenic and eye defects in Meis1 mutant animals

Meis1 and Hoxa9 expression is upregulated by retroviral integration in murine myeloid leukemias and in human leukemias carrying MLL translocations. Both genes also cooperate to induce leukemia in a mouse leukemia acceleration assay, which can be explained, in part, by their physical interaction with each other as well as the PBX family of homeodomain proteins. Here we show that Meis1-deficient embryos have partially duplicated retinas and smaller lenses than normal. They also fail to produce megakaryocytes, display extensive hemorrhaging, and die by embryonic day 14.5. In addition, Meis1-deficient embryos lack well-formed capillaries, although larger blood vessels are normal. Definitive myeloerythroid lineages are present in the mutant embryos, but the total numbers of colony-forming cells are dramatically reduced. Mutant fetal liver cells also fail to radioprotect lethally irradiated animals and they compete poorly in repopulation assays even though they can repopulate all hematopoietic lineages. These and other studies showing that Meis1 is expressed at high levels in hematopoietic stem cells (HSCs) suggest that Meis1 may also be required for the proliferation/self-renewal of the HSC.

Expression of cyclin-dependent kinase inhibitor p15(INK4B) during normal and leukemic myeloid differentiation

OBJECTIVE

Expression of the cyclin-dependent kinase inhibitor p15(INK4B) frequently is altered in myeloid malignancies. We previously demonstrated that p15(INK4B) is expressed in normal myeloid cells. The aim of this study was to investigate whether p15(INK4B) expression is restricted to the granulomonocytic lineage and to evaluate its modulation during normal and leukemic myeloid differentiation.

MATERIALS AND METHODS

Normal CD34(+) cells were cultured in serum-free media to obtain granulomonocytic, erythroid, or megakaryocytic unilineage differentiation. NB4 promyelocytic cell line and fresh leukemic blasts from seven patients with acute promyelocytic leukemia were cultured with all-trans retinoic acid. At different times of culture, cell samples were collected to evaluate p15(INK4B) by semiquantitative reverse transcriptase polymerase chain reaction.

RESULTS

p15(INK4B) mRNA was found during granulomonocytic and megakaryocytic, but not erythroid, differentiation. In the granulomonocytic lineage, p15(INK4B) was detectable when the majority of cells were at the promyelocytic stage and increased progressively in more mature elements. In the megakaryocytic lineage, p15(INK4B) was expressed in the early phase of differentiation, before megakaryoblasts had appeared, and was mantained throughout the time of culture. NB4 cell line and five of seven leukemic samples displayed undetectable or very low level of p15(INK4B) that rapidly increased during retinoic acid-induced differentiation. Two leukemic samples (both collected from two patients developing all-trans retinoic acid syndrome) showed high basal levels of p15(INK4B), which was not modified by retinoic acid treatment.

CONCLUSIONS

p15(INK4B) upregulation occurs specifically during normal granulomonocytic and megakaryocytic commitment. In acute promyelocytic leukemic blasts, p15(INK4B), which is detectable at a very low level, is promptly increased by retinoic acid. In contrast, two acute promyelocytic leukemia samples obtained from patients who developed all-trans retinoic acid syndrome showed high basal levels of p15(INK4B) that did not increase further during all-trans retinoic acid-induced differentiation.