[Sustained deep molecular response over eight years after discontinuation of imatinib for chronic myeloid leukemia].

A 72-year-old female was diagnosed with chronic phase chronic myeloid leukemia (CML) in 2001. After a short course of treatment with hydroxycarbamide, imatinib (IM) 400 mg was started. A major molecular response was presumably acquired 10 months later. IM was discontinued after treatment for 47 months in November 2005. At the same time, BCR-ABL transcript was undetectable by nested RT-PCR assay, which was equivalent to <0.00138% BCR-ABL according to the international scale. The patient is still under observation with no additional therapy, and BCR-ABL has remained negative for 102 months, to date. Furthermore, interferon was never used in this patient. IM has dramatically improved the prognosis of CML. Since no cure has yet been established, patients are recommended to continue treatment even after achieving deep molecular responses. There are several ongoing clinical trials challenging the discontinuation of IM, but long-term observation is still lacking. The sustained deep molecular response, exceeding eight years, experienced in this patient is potentially encouraging.

[Marked reactive plasmacytosis accompanied by drug eruption in a patient with aplastic anemia].

A 61-year-old woman with aplastic anemia was admitted to our hospital in October 2009 because of fever and abdominal pain. She had been treated with cyclosporin A without showing any effect. On admission, uterine cancer was diagnosed and the left uterine appendages were swollen. She was treated with cefepime for febrile neutropenia without effect, and left-sided adnexitis was diagnosed. After cefepime was changed to meropenem, marked plasmacytosis was observed in the peripheral blood (23%) and bone marrow (79%) with the appearance of skin eruption. Although the plasma cells were morphologically abnormal, the cytoplasmic immunoglobulin light chain deviation was not detected by flow cytometric analysis, and M protein was not found by serum immunoelectrophoresis. She was diagnosed with reactive plasmacytosis and treated with dexamethasone. The drug eruption and plasmacytosis improved soon after starting the treatment. Although reactive plasmacytosis is observed with a variety of conditions, including infection, neoplasms, autoimmune disorders, and hemolytic anemia, it has not been reported to accompany drug eruption. Reactive plasmacytosis is sometimes not possible to distinguish from plasma cell neoplasms on morphology alone and needs to be diagnosed comprehensively by using flow cytometric analysis and immunohistochemical evaluation.

Sorafenib induces apoptosis specifically in cells expressing BCR/ABL by inhibiting its kinase activity to activate the intrinsic mitochondrial pathway.

Although the BCR/ABL tyrosine kinase inhibitor imatinib is highly effective for treatment of chronic myelogenous leukemia and Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia, relapse with emerging imatinib resistance mutations in the BCR/ABL kinase domain poses a significant problem. Here, we show that the multikinase inhibitor sorafenib inhibits proliferation and induces apoptosis at much lower concentrations in Ton.B210 cells when driven by inducibly expressed BCR/ABL than when driven by interleukin-3. The increased sensitivity to sorafenib was also observed in cells inducibly expressing BCR/ABL with the imatinib-resistant E255K or T315I mutation. Sorafenib-induced apoptosis in these cells and Ph+ leukemic cells was synergistically enhanced by rottlerin, bortezomib, or ABT-737 and inhibited by the pan-caspase inhibitor BOC-d-fmk or the overexpression of Bcl-XL. It was further revealed that sorafenib activates Bax and caspase-3 and reduces mitochondrial membrane potential specifically in BCR/ABL-driven cells. Sorafenib also inhibited BCR/ABL-induced tyrosine phosphorylation of its cellular substrates and its autophosphorylation in Ton.B210. It was finally shown that sorafenib inhibits the kinase activity of BCR/ABL as well as its E255K and T315I mutants in in vitro kinase assays. These results indicate that sorafenib induces apoptosis of BCR/ABL-expressing cells, at least partly, by inhibiting BCR/ABL to activate the mitochondria-mediated apoptotic pathway. Thus, sorafenib may provide an effective therapeutic measure to treat Ph+ leukemias, particularly those expressing the T315I mutant, which is totally resistant to imatinib and the second generation BCR/ABL inhibitors.

A variant-type MLL/SEPT9 fusion transcript in adult de novo acute monocytic leukemia (M5b) with t(11;17)(q23;q25).

As a result of recurrent chromosomal translocations in acute leukemias, the mixed-lineage-leukemia (MLL) gene fuses with a variety of partner genes, which include several members of the septin gene family. SEPT9 is a very rare but recurrent fusion partner of MLL, and has recently been implicated in the oncogenesis of various malignancies. Herein, we report a case of de novo acute monocytic leukemia (M5b) with t(11;17)(q23;q25). MLL involvement was revealed by fluorescent in situ hybridization (FISH) analysis, and an MLL/SEP9 fusion transcript was detected by RT-PCR. Sequencing analysis further showed that, in contrast to originally reported cases, MLL exon 8 was fused not with SEPT9 exon 3 but with exon 2, which codes for the unique N-terminal region of the SEPT9_v1 isoform, the region implicated in the regulation of gene expression and cell proliferation. We did not detect any mutation of FLT3, which was expressed at a relatively low level in the leukemic cells. Relapsing after a very short complete remission, the leukemia progressed rapidly and became fatal in spite of intensive therapies including hematopoietic stem cell transplantation. It is thus suggested that, in common with the original MLL/SEPT9 cases, monocytic differentiation and a poor prognosis may also be associated with acute myeloid leukemia with the variant MLL/SEPT9 fusion transcript.

[An abdominal follicular dendritic cell tumor in Castleman's disease].

A 57-year-old man was referred to our hospital because of elevated ALP. CT and MRI scans together with abdominal angiography showed multiple masses in his abdomen and portal vein obstruction. A diagnostic laparoscopic examination revealed a tumor of 3 cm x 3 cm near the portal vein and para-aortic lymphadenopathy. Histopathological examination of the tumor showed abnormal follicles with poorly formed germinal centers, scattered large spindle cells with proliferation of small lymphocytes, and hypervascular interfollicular tissue. The spindle cells were positive for follicular dendritic cell markers CD21, CD35, and epithelial membrane antigen. The diagnosis was made of a follicular dendritic cell (FDC) tumor in Castleman's disease (CD) of the hyaline-vascular type. Although the portal vein was obstructed by the FDC tumor, blood flow to the liver was retained by collateral vein. The patient did not show any response to four courses of CHOP therapy and died of obstructive jaundice, biliary tract infection and sepsis. So far, 17 cases of FDC tumor complicating CD have been reported, with a poor prognosis in all cases.