Establishment and characterization of a new mantle cell lymphoma cell line with a NOTCH2 mutation, Arbo.

Cell lines represent an essential tool used in preclinical research. Most hematologic malignancies have a wide array of cell lines representing their respective molecular and pathologic spectra. In mantle cell lymphoma (MCL), cell lines become specifically valuable in view of the heterogeneity of this disease. Unfortunately, the number of MCL cell lines that are available for the research community remains small, with only nine cell lines available for purchase through the American Type Culture Collection (ATCC). We have established a novel blastoid MCL cell line, isolated from the malignant pleural effusion of a 69-year-old male with refractory MCL. Arbo was fully characterized with cytogenetics, immunophenotyping, whole exome sequencing and drug sensitivity assays. One of the most notable mutations identified in Arbo (but not in normal tissue) was the missense mutation NOTCH2 R2400*, which has been proposed as a clinically significant mutation in MCL seen in 5% of cases. NOTCH2 R2400* results in a truncated Notch2 protein, leading to a more stable and active protein. Using pharmacologic inhibition of Notch2, we showed a dependence of Arbo on NOTCH2 signaling, as well as a link between CD23 expression on Arbo and NOTCH2 activity. Arbo represents a NOTCH2 mutated model that is useful in MCL as well as other lymphomas with such mutation. We plan to deposit Arbo at the ATCC to be available for the research community.

Successful treatment of "accelerated" chronic lymphocytic leukemia with single agent ibrutinib: A report of two cases.

"Accelerated" chronic lymphocytic leukemia/small lymphocytic lymphoma (A-CLL) is a rare histological variant of CLL/SLL, which tends to exhibit an aggressive clinical behavior compared to CLL. Due to the rarity of A-CLL (<1% of all cases), the optimal management remains ill-defined. We report two cases of A-CLL from our institution, in which both relapsed following initial chemoimmunotherapy regimens. Both patients were treated with single agent ibrutinib, a Bruton's tyrosine kinase inhibitor (BTKi), and achieved rapid, deep and durable responses. With the absence of clear guidance on A-CLL treatment, BTKi agents should be considered in the frontline treatment of A-CLL.

Systemic vs. intrathecal central nervous system prophylaxis in primary adrenal/renal diffuse large b-cell LYMPHOMA: A multi-institution retrospective analysis and systematic review.

Primary adrenal lymphoma (PAL) and primary renal lymphoma (PRL) are rare extranodal lymphomas, predominantly of diffuse large B-cell lymphoma subtype. Primary adrenal and renal lymphomas (PARL) exhibit a high predilection for the central nervous system (CNS). Therefore, current guidelines support the use of CNS prophylaxis in PARL, particularly in cases of high-risk Central Nervous System International Prognostic Index (CNS-IPI). However, the route of administration (i.e. systemic vs. intrathecal chemotherapy) has not been clearly elucidated. With this in mind, we initiated an international collaboration and literature review to analyze 50 patient cases, 20 of which received CNS prophylaxis. Based on our analysis, we conclude that PARL may indicate a need for CNS chemo-prophylaxis in the form of systemic high-dose methotrexate (HD-MTX) over intrathecal methotrexate (IT-MTX), although IT-MTX may still have utility in certain cases.

The prognostic implications of tetraploidy/near-Tetraploidy in acute myeloid leukemia: a case series and systematic review of the literature.

The prognostic significance and optimal management of tetraploidy/near-tetraploidy acute myeloid leukemia (T/NT AML) remains unclear given its limited data. This is especially true after factoring in additional chromosomal alterations, which carry their own prognostic weight. Here, we analyze 128 cases of T/NT in AML from the literature along with two additional cases, which is the largest review of this subject to date. Based on our retrospective analysis, we found that regardless of the risk status attributed to cytogenetics, the prognosis of tetraploid or near-tetraploid AML is dismal and should be incorporated within the unfavorable risk group. Complete remission is paramount to survival in this population. Specific induction protocols for high-risk AML appear to have higher rates of complete remission in the T/NT AML population. Moreover, longer overall survival can be achieved with chemotherapy followed by allogeneic stem cell transplantation at first complete remission.

Primary Dural Diffuse Large B-cell Lymphoma: A Comprehensive Review of Survival and Treatment Outcomes.

Primary dural diffuse large B-cell lymphoma (PD-DLBCL) is a rare and aggressive B-cell non-Hodgkin lymphoma that can present in intracranial or intraspinal locations. Although the optimal management is unknown, PD-DLBCL therapy is often mirrored after primary central nervous system lymphoma therapy and aggressive treatment with a high dose methotrexate-based regimen is frequently used. Our comprehensive, retrospective study of 24 reported cases of PD-DLBCL provide the most complete analysis of this rare disease including data on biology, treatment outcomes, and survival. Our findings demonstrate good outcomes following induction treatment with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone), suggesting that these cases can be treated as DLBCL rather than primary central nervous system lymphoma, obviating the need for more aggressive and toxic approaches. The durable responses following R-CHOP also confirm that PD-DLBCL is not protected by the blood brain barrier.

A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome.

BACKGROUND: Idiopathic hypereosinophilic syndrome involves a prolonged state of eosinophilia associated with organ dysfunction. It is of unknown cause. Recent reports of responses to imatinib in patients with the syndrome suggested that an activated kinase such as ABL, platelet-derived growth factor receptor (PDGFR), or KIT, all of which are inhibited by imatinib, might be the cause. METHODS: We treated 11 patients with the hypereosinophilic syndrome with imatinib and identified the molecular basis for the response. RESULTS: Nine of the 11 patients treated with imatinib had responses lasting more than three months in which the eosinophil count returned to normal. One such patient had a complex chromosomal abnormality, leading to the identification of a fusion of the Fip1-like 1 (FIP1L1) gene to the PDGFRalpha (PDGFRA) gene generated by an interstitial deletion on chromosome 4q12. FIP1L1-PDGFRalpha is a constitutively activated tyrosine kinase that transforms hematopoietic cells and is inhibited by imatinib (50 percent inhibitory concentration, 3.2 nM). The FIP1L1-PDGFRA fusion gene was subsequently detected in 9 of 16 patients with the syndrome and in 5 of the 9 patients with responses to imatinib that lasted more than three months. Relapse in one patient correlated with the appearance of a T674I mutation in PDGFRA that confers resistance to imatinib. CONCLUSIONS: The hypereosinophilic syndrome may result from a novel fusion tyrosine kinase - FIP1L1-PDGFRalpha - that is a consequence of an interstitial chromosomal deletion. The acquisition of a T674I resistance mutation at the time of relapse demonstrates that FIP1L1-PDGFRalpha is the target of imatinib. Our data indicate that the deletion of genetic material may result in gain-of-function fusion proteins.