Complete remission in hypoplastic acute myeloid leukemia induced by G-CSF without chemotherapy: report on three cases

Repeated spontaneous remission of acute myeloid leukemia in response to various infections: a case report

BACKGROUND

Acute myeloid leukemia (AML) is a progressive hematological malignancy that can be fatal when left untreated. However, spontaneous remission is rarely observed in the presence of infectious diseases.

CASE PRESENTATION

We treated an 80-year-old woman with AML who spontaneously underwent remission after infections. Spontaneous remission was observed after each of three independent clinical infections caused by different pathogens-nontuberculous Mycobacterium infection, pulmonary aspergillosis, and Escherichia coli bacteremia. All infections were treated promptly with antimicrobials. Mycobacterium avium infection was treated with azithromycin, rifampin, and ethambutol. Pulmonary aspergillosis was treated with itraconazole followed by voriconazole. E. coli infection was treated with meropenem. During each infectious episode, leukemic cells disappeared from the patient's peripheral blood and pancytopenia improved without routine blood transfusion. These clinical effects lasted for several months. The patient has survived for > 2 years beyond the median survival time of end-stage AML. Thus, this case represents an immunological antileukemic effect of systemic infections.

CONCLUSIONS

We have discussed a common mechanism of spontaneous remission of AML without chemotherapy, clinically exhibited by infection immunology. We believe that infections exert a limited immunological effect against AML, which may prolong survival among elderly individuals with AML.

Current Understandings of Myeloid Differentiation Inducers in Leukemia Therapy

Differentiation therapy using all-trans retinoic acid for acute promyelocytic leukemia (APL) is well established. Several attempts have been made to treat non-APL, AML patients by employing differentiation inducers, such as hypomethylating agents (HMAs), and low-dose cytarabine (Ara-C) (LDAC), with encouraging results. Other than HMAs and LDAC, various inducers of myeloid cell differentiation have been identified. This review describes and categorizes these inducers, which include glycosylation modifiers, epigenetic modifiers, vitamin derivatives, cytokines, and chemotherapeutic agents. Some of these inducers are currently being used in clinical trials. I highlight the potential applications of glycosylation modifiers and epigenetic modifiers, which are attracting increasing attention in their use as differentiation therapy against AML. Among the agents described in this review, epigenomic modifiers seem particularly promising, and particular attention should also be paid to glycosylation modifiers. These drugs may signal a new era for AML differentiation therapy.

Hypoplastic acute myeloid leukemia in an elderly patient. A long-term partial remission with low-dose prednisone and G-CSF

Hypoplastic acute myeloid leukemia (AML) is a rare variant of AML that mainly affects the elderly and accounts for 5%-7% of de novo AML. Prognosis for this disease is poor, and there is no standard therapy. We have treated an elderly patient with hypoplastic AML with low-dose prednisone and G-CSF with good results. We propose that this treatment may be a viable alternative to supportive therapy alone, or the tenuous chemotherapeutic challenge to elderly patients with hypoplastic AML.

Hypocellular acute myeloid leukemia treated with bone marrow transplantation

Hypocellular acute myeloid leukemia (AML) mainly occurs in elderly patients, and is extremely rare in childhood. There is still no established treatment for hypocellular AML. We report the case of an 11-year-old boy with hypocellular AML who was treated successfully with allogenic bone marrow transplantation (allo-BMT). He presented with fever, pallor and pancytopenia. Bone marrow aspiration and biopsy confirmed a diagnosis of hypocellular AML. Although low-dose cytarabine induced reduction of blasts, it did not lead to complete remission. He subsequently received myeloablative conditioning and allo-BMT. Graft-versus-host disease (GVHD) prophylaxis included short-course methotrexate and cyclosporine. Neutrophil engraftment (>5 × 10⁸ /L) and platelet recovery (>10 × 10¹⁰ /L) were achieved on days 13 and 27, respectively. He developed acute GVHD of the skin (grade 2), which responded well to treatment with prednisolone. He has remained in complete remission for 5 years since allo-BMT. We consider allo-BMT to be feasible for children with hypocellular AML.

HAG regimen improves survival in adult patients with hypocellular acute myeloid leukemia

Background

Hypocellular acute myeloid leukemia (Hypo-AML) is a rare disease entity. Studies investigating the biological characteristics of hypo-AML have been largely lacking. We examined the clinical and biological characteristics, as well as treatment outcomes of hypo-AML in our institutes over a seven years period.

Design and Methods

We retrospectively analyzed data on 631 adult AML patients diagnosed according to the French-American-British (FAB) classification and WHO classification of tumors of haematopoietic and lymphoid tissue, including 43 patients with hypo-AML. Biological variables, treatment outcomes and follow-up data on hypo-AML patients were analyzed.

Results

Out of 631 AML patients, 47 (7.4%) were diagnosed as hypo-AML, out of which 43 patients were evaluable. Compared with non-hypocellular AML, hypo-AML patients tended to be older (P = 0.05), more likely to present with leukocytopenia (P < 0.01) and anterior hematological diseases (P = 0.02). The overall complete remission (CR) rate, disease free survival (DFS), and overall survival (OS) in hypo-AML patients were comparable to those in non-hypo AML patients. Twenty-seven (62.8%) patients with hypocellular AML were treated with the standard regimen of anthracyclines and cytarabine (XA) (associated CR rate: 51.9%; median OS: 7 months; median DFS: 6.5 months). Sixteen (37.2%) patients were treated with a priming regimen containing homoharringtonine, cytarabine and G-CSF (HAG) (associated CR rate: 81.25%; median OS: 16 months; median DFS: 16 months).

Conclusions

The overall prognosis of hypo-AML was not inferior to that of non-hypo AML. HAG regimen might increase response rates and improve survival in hypo-AML patients.

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.

Effects of granulocyte-colony stimulating factor and the expression of its receptor on various malignant cells

Background

Granulocyte-colony stimulating factor (G-CSF) is extensively used to improve neutrophil count during anti-cancer chemotherapy. We investigated the effects of G-CSF on several leukemic cell lines and screened for the expression of the G-CSF receptor (G-CSFR) in various malignant cells.

Methods

We examined the effects of the most commonly used commercial forms of G-CSF (glycosylated lenograstim and nonglycosylated filgrastim) on various leukemic cell lines by flow cytometry. Moreover, we screened for the expression of G-CSFR mRNA in 38 solid tumor cell lines by using real-time PCR.

Results

G-CSF stimulated proliferation (40-80% increase in proliferation in treated cells as compared to that in control cells) in 3 leukemic cell lines and induced differentiation of AML1/ETO+ leukemic cells. Among the 38 solid tumor cell lines, 5 cell lines (hepatoblastoma, 2 breast carcinoma, squamous cell carcinoma of the larynx, and melanoma cell lines) showed G-CSFR mRNA expression.

Conclusion

The results of the present study show that therapeutic G-CSF might stimulate the proliferation and differentiation of malignant cells with G-CSFR expression, suggesting that prescreening for G-CSFR expression in primary tumor cells may be necessary before using G-CSF for treatment.

Successful treatment of childhood hypocellular acute myeloid leukemia

Hypocellular acute myeloid leukemia (AML) is extremely rare in childhood. We report on a 7-year-old girl with hypocellular AML who was treated successfully with granulocyte-colony stimulating factor (G-CSF) and combined chemotherapy. High-dose G-CSF induced complete remission and she subsequently received reduced intensity conditioning and unrelated cord blood transplantation; however, this resulted in early rejection. After a complete hematological recovery, she received 3 courses of combination chemotherapy oriented toward AML. She has remained in complete remission for over 1 year after the completion of the therapy. G-CSF effectively induced remission, and combination chemotherapy has been proven to be feasible for patients with childhood hypocellular AML.

Hematological Remission and Long Term Hematological Control of Acute Myeloblastic Leukemia Induced and Maintained by Granulocyte-colony Stimulating Factor (G-CSF) Therapy

We describe a case of a patient with CD34+, TdT+, CD13-, CD33-, MPO- undifferentiated acute leukemia who refused chemotherapy and who achieved complete hematological remission 14 months after the diagnosis, during a short course of granulocyte-colony stimulating factor (G-CSF) for neutropenia and life threatening infection. Relapse occurred approximately one year later and G-CSF was reintroduced, being maintained for 4 months, at a dose and frequency adapted to maintain normal blood counts, a complete hematological remission being achieved again. Five months after withdrawing the G-CSF therapy a second relapse was observed; G-CSF was tried again with success, resulting in a very good hematological response that was sustained by G-CSF maintenance therapy. One year latter there was the need of increasing the doses of G-CSF in order to obtain the same hematological effect, at same time blast cells acquired a more mature CD34+, TdT-, CD13+, CD33-, MPO+ myeloid phenotype. Finally, the patient developed progressive neutropenia, anemia, thrombocytopenia and acute leukemia in spite of G-CSF therapy, dying 64 months after initial diagnosis (50 months after starting G-CSF therapy) with overt G-CSF resistant acute myeloblastic leukemia (AML), after failure of conventional induction chemotherapy.

Spontaneous remission of acute monocytic leukemia after infection with Clostridium septicum

Spontaneous remissions of acute myeloid leukemia (AML) have been reported in association with infection. Here, we report a case of spontaneous remission of AML in a 47-year-old Saudi Arabian male patient who presented with a few weeks history of recurrent abdominal pain, vomiting and fever. He was diagnosed with acute monocytic leukemia (AML, FAB M5b) and a perforated bowel. He also had Clostridium septicum bacteremia and thus chemotherapy was deferred. He received supportive therapy and intravenous antibiotics. Six weeks later, he achieved spontaneous and complete remission lasting for about 4 months. The remission and relapse were documented by bone marrow examination. Similarly, previous reports of spontaneous remission of AML were short lived and were followed by relapse and progression.

Effect of low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor priming (CAG regimen) on the outcome of elderly patients with acute myeloid leukemia

The aim of this study was to evaluate the efficacy and toxicity of low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor (G-CSF) protocol in elderly patients with acute myeloid leukemia (AML). A total of 50 elderly patients including 8 aged over 70 years were enrolled. All patients were treated with CAG regimen including low-dose cytarabine (10mg/m(2) every 12h, days 1-14), aclarubicin (10mg every day, days 1-8), and G-CSF (200 microg/m(2) every day, days 1-14) priming. The overall response rate was 72.0%, and 29 of 50 (58.0%) patients achieved complete remission, including 23 of 35 (65.8%) with previously untreated AML, 6 of 15 (40.0%) with refractory, relapsed or secondary AML, 4 of 8 (50.0%) aged over 70 years, 4 of 10 (40.0%) with unfavorable cytogenetic aberrations. The early death rate was 7.6%. The median overall survival was 14 months. Myelosuppression was mild to moderate, severe nonhematologic toxicity was not observed. Thus CAG priming regimen as the induction therapy is well tolerated and effective in elderly patients with AML.

Cytokines in the differentiation therapy of leukemia: from laboratory investigations to clinical applications

Differentiation therapy of leukemia is the treatment of leukemia cells with biological or chemical agents that induce the terminal differentiation of the cancer cells. It is regarded as a novel and targeted approach to leukemia treatment, based on our better understanding of the hematopoietic process and the mechanisms of its deregulation during leukemogenesis. Clinically, differentiation therapy has been most successful in acute promyelocytic leukemia using all-trans-retinoic acid as the inducer, either alone or in combination with chemotherapy. This review presents evidence that a number of hematopoietic cytokines play important roles in both normal and aberrant hematopoietic processes. In vitro laboratory investigations in the past two decades using well-characterized myeloid leukemic cell lines and primary blast cells from leukemia patients have revealed that many hematopoietic cytokines can trigger lineage-specific differentiation of leukemia cells, which may have important implications in the clinical setting. Moreover, our current understanding of cytokine interactions and the molecular mechanisms of cytokine-induced leukemic cell differentiation will be discussed in the light of recent findings. Finally, ways in which laboratory research on cytokines in the differentiation therapy of leukemia can lead to the improved design of protocols for future clinical applications to leukemia therapy will also be addressed.

Therapeutic use of granulocyte-colony stimulating factor could conceal residual malignant cells in patients with AML1/ETO+ acute myelogenous leukemia

We have experienced a number of cases of AML1/ETO+ acute myelogenous leukemia that showed remission based on bone marrow (BM) morphological criteria, but that revealed clonal abnormalities in most cells by fluorescence in situ hybridization (FISH). Interestingly, most of these cases had AML with AML1/ETO rearrangement. The malignant cells were differentiated and considered mature cells after granulocyte-colony stimulating factor (G-CSF) treatment. To clarify the possible mechanisms underlying this phenomenon, we investigated the expression levels of G-CSFR in AML cells with AML1/ETO rearrangement by flow cytometry and real-time polymerase chain reaction (PCR). The number of AML1/ETO+ cells expressing G-CSFR at baseline was significantly higher than that of AML1/ETO- AML cells (2673 vs 522). In addition, the G-CSFR gene was more highly expressed in AML1/ETO+ cells than in AML1/ETO- cells by real-time PCR. This study reveals that cases showing remission after treatment with G-CSF mostly had leukemia with AML1/ETO rearrangement. This finding might be explained by the higher expression of G-CSF receptor in AML1/ETO+ cells than in AML1/ETO- cells. We recommend that remission should be confirmed by FISH, because malignant clones can be differentiated and masked in morphological examination or chromosome test, especially for AML with AML1/ETO rearrangement.