Glucocorticoid and Antibiotic Treatment-induced Recapitulated Hematological Remissions in Acute Myeloid Leukemia: Implications for Ligand-dependent Growth and Survival Advantage

Leukemia-transformed multipotential hematopoietic cells have acquired the increased self-renewal capacity and impaired myeloid differentiation to mature blood cells. The emergence of symptomatic leukemia also critically requires the acquisition of growth and survival advantage in leukemic cells. Untreated leukemia patients usually demonstrated a progressive process. However, spontaneous remission occasionally occurred in a very small number of leukemia patients, which frequently followed a febrile episode and antibiotic treatment and was generally attributed to the activation of anti-neoplastic activities. Here we report a 63-year-old Chinese man who presented with the main complaints of abdominal pain, febrile episode and urticaria-like skin lesions. He was diagnosed with acute myeloid leukemia (AML-M4) with t(8;21)(q22;q22)/RUNX1-RUNX1T1 on the basis of morphological, immunological, cytogenetic and molecular analysis. He also had a mutated FLT3-TKD gene. He was treated with antibiotics and glucocorticoid for the gastrointestinal infection and the urticaria-like skin lesions. The infection and skin lesions were quickly resolved. Unexpectedly, along with the relief of the febrile episode, abdominal symptoms and skin lesions, he achieved a hematological remission. After relapse, repeating this treatment resulted in the second hematological remission. These recapitulated treatment responses strongly suggested that inammatory stresses arising from the gut inammatory lesions, which could be largely mitigated by antibiotic and glucocorticoid treatment, sustained the growth and survival advantage of the leukemic cells.


Background
Acute myeloid leukemia (AML) is a malignant hematological disease caused by a sequence of somatic mutations in multipotential hematopoietic cells. Leukemia-transformed multipotential hematopoietic cells have acquired the enhanced self-renewal capacity and the impaired myeloid differentiation to mature blood cells. The emergence of symptomatic AML not only requires the acquisition of increased self-renewal capacity but also critically requires the acquisition of growth and survival advantage in leukemic cells. It is the growth and survival advantage that lead to the accumulation and in ltration of a large amount of clonal leukemic cells in the bone marrow, taking up the hematopoietic pool, inhibiting the polyclonal normal hematopoiesis and ultimately resulting in the decreased capacity of producing mature blood cells. Anemia due to the decreased production of red blood cell, spontaneous hemorrhage due to the deceased production of platelet, and infection due to the decreased production of mature white blood cell are the major clinical presentations in AML patients [1][2][3].
Chemotherapy is currently the main initial treatment for AML, the aim of which is to reduce the large amount of leukemic cells and to achieve a complete hematological remission. Untreated AML patients usually demonstrated a progressive process [1]. However, spontaneous remission occasionally occurred in a very small proportion of untreated AML patients, which frequently followed a febrile episode and antibiotic treatment and was generally attributed to the activation of anti-neoplastic activities [5][6][7][8][9][10][11][12].
This spontaneous remission could occur not only in patients with recurrent cytogenetic abnormalities but also in patients with gene mutations in transcription factors. Here, we report a AML patient with t(8;21) (q22;q22)/RUNX1-RUNX1T1 who achieved an unexpected hematological remission after antibiotic and glucocorticoid treatment for his abdominal infection and the urticaria-like skin lesions. After relapse, repeating this treatment resulted in the second hematological remission, suggesting the recapitulated treatment responses.

Case Presentation
A 63-year-old Chinese man presented with the major complaints of abdominal pain and fever for 3 days, in the absence of headache, dizziness, chest pain, dyspnoea, cough and sputum. The highest body temperature was 39.7℃. On physical examination, prominent signs were the urticaria-like skin lesions and the pan-abdominal tenderness. Complete blood count (CBC) showed the following: white blood cells After admission, He was treated with piperacillin-tazobactam and etimicin for his febrile disease and dexamethasone for his urticaria-like skin lesions. He was also prescribed polyglycol electrolyte solution (1500 ml daily for 2 days) followed by rifaximin (200 mg four times daily) and berberine (0.3 g thrice times daily) in an attempt to quickly get rid of the pathogens and their metabolites in the intestines.The febrile episode and the urticaria-like skin lesions were quickly resolved. Surprisingly, the hematological pro le gradually improved (CBC results in the following time are outlined in Fig. 4). On day 31, CBC showed the following: WBC, 10.83×10 9 /L; neutrophils, 6.24×10 9 /L; monocytes, 1.62×10 9 /L; RBC, 2.74×10 12 /L; Hb, 93 g/L; Plt, 253×10 9 /L; and Ret, 112.45×10 9 /L. The absence of leukemia cells on blood smears indicated the loss of clonal growth advantage and an achievement of clinical hematological remission. He refused chemotherapy and hypomethylation therapy and was released. on day 51, he was admitted with the same symptoms as he was rst admitted to our center. CBC and morphological examination of the blood smears con rmed the disease recurrence. Repeating the abovementioned treatment resulted in the second clinical and hematological responses. On day 105, he experienced the second recurrence, demonstrated resistance to antibiotic treatment and died of septic shock at another hospital.

Discussion And Conclusions
While acquisition of enhanced self-renewal capacity and impaired myeloid differentiation is the feature of acute leukemia, the emergence of symptomatic AML critically requires the acquisition of growth and survival advantage. Acquisition of enhanced self-renewal capacity results from the fused genes such as in recurrent chromosome arrangements and the mutated genes such as in transcription factor signaling pathways responsible for differentiation in certain lineage and certain stage of hematopoietic progenitors. Acquisition of clonal growth advantages results from the fused genes or mutated genes in growth receptors or their signaling pathways [1][2][3].
It is generally accepted that the constitutionally activated growth factor receptor signaling pathways are responsible for the growth and survival advantage in leukemic stem cells such as the formation of fused genes involving ABL, FGFR1 and PDGFR and mutated genes involving FLT3 and KIT, which result in the autonomous proliferation [1][2][3]. However, there may be another form of activating growth factor receptor signaling pathways in AML, ligand-dependent activation, like mutated genes in the B-cell receptor signaling pathway in lymphoma pathogenesis in which the antigen-dependent growth and survival advantages has been well elucidated [13][14][15][16][17]. In this setting, mutated genes in growth factor receptor signaling pathways may play a tonic role in intensifying the proliferative signaling after ligands binding to their receptors, and thereby acquiring the growth and survival advantage. Clonal B cells proliferate in response to antigen binding to B-cell receptors [13][14][15][16][17]; myeloid hematopoietic cells proliferate in response to ligands binding to pattern recognition receptors, cytokine receptors and colony stimulating factor receptors [18][19][20][21][22].
In our reporting case, the presence of increased percentages of blasts and CD 34 + progenitors in the bong marrow, the detection of chromosome arrangement of t(8;21)(q22;q22) and fused AML1-ETO gene ful lled the diagnosis of AML with recurrent chromosome arrangement of t(8;21)(q22;q22)/RUNX1-RUNX1T1. When admission, he presented with a febrile episode, overt gastrointestinal symptoms and urticaria-like skin lesions. In this setting, he was prescribed antibiotics to treat the febrile episode, dexamethasone to treat the urticaria-like skin lesions and a gut-cleansing preparation to quickly remove the gastrointestinal pathogens. Along with the relief of the gastrointestinal infections and the urticarialike skin lesions, his hematological pro le had been signi cantly improved. The absence of leukemia cells on the blood smears suggested an achievement of clinical hematological remission. Because he refused chemotherapy and hypomethylation therapy, we had the opportunity to observe the recapitulated treatment response. These recapitulated treatment responses suggested that altered in ammatory stresses contributed to the loss of clonal growth and survival advantage, in support of a liganddependent clonal growth advantage. This ligand could be intestine-derived pathogen-associated molecular pattern, cytokine or colony stimulating factor produced in response to infectious offending [18][19][20][21][22]. After the second relapse, he demonstrated resistance to antibiotic and glucocorticoid treatment and died of septic shock probably due to the acquisition of a new pathogenic infection like our previously reported case [23] Taken together, the recapitulated antibiotic and glucocorticoid treatment-induced hematological remissions strongly indicated a ligand-dependent growth advantage in AML emergence. This phenomenon warrants further investigations and may be helpful in improving therapeutic outcome in a subgroup of AML. Consent for publication: Written informed consent was obtained from the patient' son for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editors-in-Chief of this journal Availability of data and materials: All data generated or analyzed during this study are included in this published article.
Competing interests: The authors have no con icts of interest to declare that are relevant to the content of this article. Authors' contributions: XYS and XCZ developed the idea, XYS, XQY, and XDY participated in treating the patients and collected the data, XYS and SXX analyzed the data and wrote the manuscript, FJM and XCZ supervised the treatment and revised the manuscript, XCZ decided and approved the nal version. All authors read and approved the nal manuscript.  Figure 1 Abdominal CT imaging of the patient: abnormally accumulated airs in the small intestines (marked by yellow arrows); signi cantly thickened and air-lled distal ileum (marked by black arrows), markedly thickened descending colon (marked by red arrows) and lipotrophic lesions with overt angiogenensis surrounding the unusually thinned and distended small intestines (marked by yellow arrows) and sigmoid colon (marked by a purple arrow).

Figure 2
Morphological evaluation of the bone marrow and peripheral blood smears. A: a heavily hypercellular bone marrow with the increased percentages of monoblasts (accounting for 44.5% of the total nucleated hematopoietic cells) and premonocytes (accounting for 24.5%). B: Increased percentages of premonocytes (accounting for 44%) and monocytes (accounting for 46%).