CNS relapses of acute promyelocytic leukemia after all-trans retinoic acid

Central Nervous System Double Relapse of Acute Promyelocytic Leukemia and Acute Myelomonocytic Leukemia

Relapse of acute promyelocytic leukemia (APL) and non-M3-acute myeloid leukemia in the central nervous system (CNS) are rare events. Here, we describe a case of simultaneous relapses of APL and acute myelomonocytic leukemia on the CNS of a patient after allogeneic bone marrow transplant. This extremely unusual case highlights the difficulties that CNS leukemia relapses pose in the post-transplant setting.

Leptomeningeal Relapse of Acute Promyelocytic Leukemia

Extramedullary relapse (EMR) of acute promyelocytic leukemia (APL) is a rare entity, with predilection to involve the central nervous system (CNS). Risk factors include leukocytosis of > 10 × 10⁹/L, bcr3 isoform, microgranular variant, age > 45 years and development of subarachnoid hemorrhage (SAH) during induction therapy. We report a case of APL who completed induction and consolidation therapy but subsequently relapsed with leptomeningeal involvement. Retrospectively, we identified several risk factors for EMR in our patient. Interestingly, the use of all-trans retinoic acid has recently been associated with higher risk of EMR possibly due to up-regulation of adhesion molecules on the surface of the leukemic cell, resulting in their passage through the endothelium to extramedullary tissues. However, data remain conflicting in that regard. Although universal CNS prophylaxis has been suggested, the low incidence of EMR among APL patients renders this strategy less attractive. Nonetheless, active surveillance and CNS prophylaxis may be considered in patients at high risk for EMR, particularly in those of SAH during induction therapy. Further research is needed to evaluate the effectiveness and safety of this strategy.

How I treat children and adolescents with acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APL) is a rare subtype of acute myeloid leukaemia. The outcome of paediatric APL has improved substantially over the past 20 years; cure rates above 80% are expected when all-trans retinoic acid (ATRA) is given with anthracycline-based regimens. The presenting features of paediatric APL may include severe bleeding and thrombotic complications, which contribute to the high early death rate. The incidence of leucocytosis and the microgranular subtype is greater in paediatric than adult APL, and children experience greater ATRA-related toxicity. It is crucial to begin ATRA therapy and intensive platelet and fibrinogen replacement on first suspicion of APL. Recent risk-adapted therapeutic trials have shown that patients at greater risk of relapse benefit from the introduction of high-dose cytarabine during consolidation. Combination therapy with ATRA and arsenic trioxide provides very effective frontline treatment and may reduce the need for subsequent anthracycline therapy.

Extramedullary disease in acute promyelocytic leukemia: two-in-one disease

In acute promyelocytic leukemia (APL), extramedullary disease (EMD) is particularly rare and shows special clinical and biological features. It is estimated that about 3-5% of APL patients will suffer extramedullary relapse. The most common site of EMD in APL is the central nervous system (CNS). At present, there are still many issues of EMD in APL needing further clarification, including pathogenesis, risk factors, prognosis and treatment. A better understanding of the biological mechanisms underlying EMD is important to be able to devise more effective CNS prophylaxis and induction-consolidation therapeutic strategies.

In vitro and in vivo apoptosis-inducing antileukemic effects of Mucuna macrocarpa stem extract on HL-60 human leukemia cells

Mucuna macrocarpa Wallich (Leguminosae) is believed to hold blood circulation activating effects, and has been used as a folk remedy in Southeast Asia for the treatment of various hematologic and circulatory-related ailments. The objective of this study was to investigate whether crude methanolic extract of M macrocarpa (CMEMM) possessed antileukemic effects on HL-60, human leukemia cells. CMEMM was prepared from dried stems of this plant, and its apoptosis-inducing effects were investigated using HL-60 cells in vitro and in vivo. With treatment of 25 to 75 μg/mL CMEMM, the in vitro antiproliferative effect on HL-60 cells increased in a dose- and time-dependent manner during the 72-hour treatment period. The concentration of CMEMM that exhibited a 50% growth inhibition (IC(50)) for 72-hour exposure was 36.4 μg/mL. Apoptosis triggered by CMEMM in HL-60 cells was confirmed by the following observations: ( a) characteristic apoptotic nuclear fragmentation, (b) dose-dependent accumulation of sub-G(1) phase in cell cycle analyses, (c) increased percentages of annexin V-positive apoptotic cells, and (d) dose-dependent elevation of active caspase-3. Furthermore, an in vivo tumor growth suppression effect by CMEMM (500 mg/kg/d intraperitoneally) was observed in mouse xenografts. The results suggest that CMEMM exerts antileukemic effects via an apoptotic pathway in HL-60 cells, and could be a candidate for developing antileukemic agents in the future.

Promyelocytic sarcoma of the spine: a case report and review of the literature

Myeloid sarcoma (MS, previously named granulocytic sarcoma or chloroma) is a rare extramedullary tumour of immature myeloid cells. It can be present before, concurrently with, or after the diagnosis of acute myeloid leukemia. MS is extremely uncommon in acute promyelocytic leukemia (APL). In the case described here, MS was the sole site of APL relapse and the cause of spinal cord compression. The patient presented with neurologic symptoms due to a paravertebral mass of MS after 7 years of complete remission. He was treated with excision of the mass followed by local radiotherapy. Systemic treatment was also given with combined arsenic trioxide and all-trans retinoic acid and the patient was able to achieve a second prolonged clinical and molecular remission.

Incidence of extramedullary disease in patients with acute promyelocytic leukemia: a single-institution experience

Using current treatment regimens, over 90% of patients with acute promyelocytic leukemia will achieve complete remission (CR). However, approximately 30% of these patients will relapse, including a small proportion who will develop extramedullary disease (EMD). In this study, we investigated the incidence of EMD in 263 patients with APL who were treated at our institution from January 1990 to May 2008. With a median follow-up of 31 months (range 2 days-203 months), 8 (3%) patients developed EMD. The most commonly affected site was the central nervous system (n = 7). Before developing EMD, one patient had achieved CR with a chemotherapy-only regimen, six patients had achieved CR with all-trans-retinoic acid (ATRA)-based regimens, and one patient had achieved CR with an ATRA plus arsenic trioxide (ATO)-based regimen. The EMD conferred a poor prognosis; five patients died within 4 months of developing EMD. The molecular status did not predict EMD; four patients had a negative PCR for the PML-RARA transcripts prior to relapse with EMD. In conclusion, the incidence of EMD is low. We were unable to identify any specific factors that could predict the development of EMD.

Engraftment of human blood malignancies to the turkey embryo: a robust new in vivo model

Xenografting of human blood malignancies to immunodeficient SCID mice is a powerful research tool. We evaluate here whether the immunodeficient turkey embryo can also serve as a xenograft host for human blood malignancies. Human leukemia, lymphoma and myeloma lines engrafted robustly into medullary and extramedullary tissues of turkey embryos as detected by PCR, FACS and histology in 8-10 days. Four of eleven patient AML samples also engrafted the bone marrow. Grafts of two lines responded to chemotherapy with doxorubicin. The turkey embryo therefore has the potential to be a complementary xenograft model for the study of human blood malignancies.

Acute promyelocytic leukemic involvement of the optic nerves following mitoxantrone treatment for multiple sclerosis

Mitoxantrone, the first immunosuppressant to receive FDA approval for treatment of worsening relapsing-remitting, secondary progressive, and progressive-relapsing multiple sclerosis (MS) is a DNA topoisomerase II inhibitor that has been associated with the development of acute promyelocytic myelogenous leukemia (APML). Central nervous system APML is a rare site of extramedullary involvement following mitoxantrone therapy. We report a patient with history of multiple sclerosis who developed bilateral optic nerve involvement as the primary manifestation of APML relapse following mitoxantrone treatment.

Presentation of acute promyelocytic leukemia as granulocytic sarcoma

Granulocytic sarcoma (GS) is a localized tumor composed of immature myeloid cells. This extramedullary tumor can present before, concurrent with or after the diagnosis of acute myeloid leukemia. GS is extremely uncommon in acute promyelocytic leukemia (APL). As a proportion of patients never develop systemic disease, correct and timely diagnosis may be rather difficult, but is a prerequisite for optimal outcome. GS should be considered in the differential diagnosis of children with unusual bone lesions. We describe a patient with GS who presented with symptoms mimicking osteomyelytis or rheumatoid disease.

Isolated central nervous system relapse in childhood acute promyelocytic leukemia

Central nervous system (CNS) involvement is rare in acute promyelocytic leukemia (APL). The majority of CNS relapses occur in patients with hyperleukocytosis at presentation, and the optimal management of such patients is still controversial. We describe a 13-year-old boy with APL who developed an isolated CNS relapse after first-line treatment with all-trans retinoic acid and chemotherapy. A second remission was achieved with a regimen consisting of intrathecal chemotherapy, intravenous high-dose cytarabine, and oral 6-mercaptopurine. All-trans retinoic acid was avoided owing to severe complications during initial therapy. The patient remains in molecular remission at 9 months after autologous stem cell transplant. Prognostic factors of CNS relapse in children with APL are needed to define the indications for CNS prophylaxis in this group of patients.

Extramedullary disease and targeted therapies for hematological malignancies—is the association real?

During the past years targeted therapies have gained a major role in the treatment of cancer patients, including those with hematological malignancies. Extramedullary involvement is a rare manifestation of acute and chronic leukemias and of multiple myeloma. Nevertheless, with the expanding use of targeted treatments there is an impression that the incidence of extramedullary relapses is increasing. We reviewed the reports on this phenomenon in patients treated with all-trans-retinoic acid and arsenic trioxide for acute promyelocytic leukemia, thalidomide and bortezomib for multiple myeloma and imatinib for chronic myeloid leukemia. The pathogenetic mechanisms suggested are: life prolongation by these treatments allowing for disease progression arising from dormant cells; poor penetration of the drugs to sanctuary sites like the central nervous system; the requirement of some of these drugs, especially thalidomide, for the marrow microenvironment to exert their action; and finally, a possible active role for some of the drugs, like all-trans-retinoic acid. Since the use of these targeted therapies is expanding we should be aware of this association.

Effects of 1, 6-Bis[4-(4-amino-3-hydroxyphenoxy)phenyl]diamantane (DPD), a reactive oxygen species and apoptosis inducing agent, on human leukemia cells in vitro and in vivo

1, 6-Bis[4-(4-amino-3-hydroxyphenoxy)phenyl]diamantine (DPD), a new cytostatic and differentiation inducing agent, was found to inhibit the growth of several cancer cell lines in the National Cancer Institute (NCI) Anticancer Drug Screen system. Previously, we demonstrated that DPD inhibited the growth of human colon cancer cell lines both in vitro and in vivo. In this study, we examined the anticancer effects of DPD on two human leukemia cells lines. DPD exerted growth inhibitory activities in vitro against two human leukemia cell lines, the promyeloid line HL-60 and the lymphoblastic line Molt-3. The in vivo effect of tumor growth suppression by DPD was also observed in mouse xenografts. No acute toxicity was observed after an intra-peritoneal challenge of DPD in "severe combined immune-deficiency" (SCID) mice twice a week. The in vitro study showed HL-60 was more sensitive to DPD than Molt-3 through induction of G(0)/G(1) cell-cycle arrest with the appearance of a hypodiploid DNA fraction. The increased superoxide (O(2)(-)), dissipation of the mitochondrial membrane potential, activation of caspase 3, and increase in annexin V binding were evident before apoptosis in DPD-treated cells. The superoxide dismutase 1 (SOD1) mRNA expression was also decreased in DPD-treated HL-60 and Molt-3 cells. Thus, it appeared that inhibition of SOD might be the major cause for the production of cellular superoxide with concomitant decrease of H(2)O(2) in DPD-treated cells. Addition of antioxidant can reduce DPD-induced mitochondrial damage, caspase activation, and annexin V binding in HL-60 cells. The results suggest that the cellular generation of O(2)(-) plays a role in initiating and coordinating DPD-mediated growth arrest and apoptosis of HL-60 cells. Importantly, addition of arsenic trioxide, a compound capable of reactive oxygen species (ROS) generation, significantly enhanced the in vitro activity of DPD. These results suggest that DPD appears to be a potential new modality in human leukemia therapy.

Meningeal relapse in a patient with acute promyelocytic leukemia: a case report and review of the literature

The involvement of central nervous system is rare in acute promyelocytic leukemia (APL). We report a APL patient of a 41 yr-old Korean male who presented with fever and petechia. Complete molecular remission was achieved with all-trans retinoic acid (ATRA), idarubicin, and cytarabine. Ten months later, he complained of a mild headache. The results of the physical examination and the complete blood counts were normal. The examination of cerebrospinal fluid showed the presence of promyelocyte. Bone marrow studies showed cytogenetic remission but with molecular relapse. He was treated with intrathecal and systemic chemotherapy.