Chronic lymphoid leukemias other than chronic lymphocytic leukemia: diagnosis and treatment

T-Cell Prolymphocytic Leukemia: Diagnosis, Pathogenesis, and Treatment

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells. Most patients with T-PLL present with lymphocytosis, anemia, thrombocytopenia, and hepatosplenomegaly. Correct identification of T-PLL is essential because treatment for this disease is distinct from that of other T-cell neoplasms. In 2019, the T-PLL International Study Group (TPLL-ISG) established criteria for the diagnosis, staging, and assessment of response to treatment of T-PLL with the goal of harmonizing research efforts and supporting clinical decision-making. T-PLL pathogenesis is commonly driven by T-cell leukemia 1 (TCL1) overexpression and ATM loss, genetic alterations that are incorporated into the TPLL-ISG diagnostic criteria. The cooperativity between TCL1 family members and ATM is seemingly unique to T-PLL across the spectrum of T-cell neoplasms. The role of the T-cell receptor, its downstream kinases, and JAK/STAT signaling are also emerging themes in disease pathogenesis and have obvious therapeutic implications. Despite improved understanding of disease pathogenesis, alemtuzumab remains the frontline therapy in the treatment of naïve patients with indications for treatment given its high response rate. Unfortunately, the responses achieved are rarely durable, and the majority of patients are not candidates for consolidation with hematopoietic stem cell transplantation. Improved understanding of T-PLL pathogenesis has unveiled novel therapeutic vulnerabilities that may change the natural history of this lymphoproliferative neoplasm and will be the focus of this concise review.

De-Novo B-Cell Prolymphocytic Leukemia

B-cell prolymphocytic leukemia (B-PLL) is a rare B-cell neoplasm that typically presents with splenomegaly, a rising white blood cell count, and may or may not have B symptoms. The diagnosis usually requires a bone marrow biopsy and aspirate with flow cytometry and cytogenetic studies. At least 55% of the lymphocytes in the peripheral blood must be prolymphocytes to be defined as B-PLL. A thorough differential diagnosis would include mantle cell lymphoma, chronic lymphocytic leukemia (CLL) with prolymphocytes, hairy cell leukemia, and splenic marginal zone lymphoma. B-PLL is managed with regimens utilized for CLL, such as ibrutinib and rituximab but is tailored for each individual. The authors report a rare case of B-PLL in a patient with no known history of CLL. The authors discuss this entity in context of the 2017 and 2022 World Health Organization (WHO) classifications, the latter of which no longer recognizes B-PLL as a distinct entity. The authors hope that this article helps practitioners with the diagnosis and treatment of B-PLL. Perhaps with better recognition, and better documentation of histopathologic features of these rare cases going forward, it may prove to be a distinct entity again in future classifications.

Sustained MRD negative remission in del17p and TP53 mutated B cell prolymphocytic leukemia with ibrutinib and venetoclax

B cell prolymphocytic leukemia is a rare and aggressive disorder often with high risk features including TP53 mutation, deletion 17p and complex karyotype. There is scarcity of data regarding treatment and existing therapies induce short lived remissions. Ibrutinib, a Bruton tyrosine kinase inhibitor, has had success in some patients with high risk features. Venetoclax, a BCL-2 inhibitor, has primarily been used in the relapsed setting. We present a case of B PLL with deletion 17p and mutated TP53 treated with ibrutinib and venetoclax in the frontline setting which resulted in measurable/minimal residual disease negative remission for approximately three years.

An Unusual Case of Prolymphocytic Leukemia Transformation in a Patient With Chronic Lymphocytic Leukemia

B-cell prolymphocytic leukemia (B-PLL) is a rare leukemia characterized by rapidly increasing leukocytosis with splenomegaly and lymphadenopathy. Treatment strategies are largely based on studies of chronic lymphocytic leukemia (CLL). Antibodies against the cell surface protein CD20 are considered to be first-line therapy. A 76-year-old male with known CLL presented 2 weeks after starting chemoimmunotherapy for newly refractory CLL after failing ibrutinib therapy. White blood cell count was elevated at 226.7 × 10³/µL. Fluorescent in situ hybridization analysis of a bone marrow specimen showed new development of complex cytogenetics. Flow cytometry revealed B cells appearing slightly dimmer on CD45 and brighter on CD20 compared with typical B-CLL suggestive of less mature lymphocyte forms. The patient was diagnosed with B-PLL and started on obinutuzumab and venetoclax with rapid normalization of white blood cells. This case recapitulates the challenges in diagnosing and treating B-PLL. Ibrutinib resistance is a growing area of study with several proposed mechanisms of acquired resistance. The pathogenesis of B-PLL is not completely understood, although mutations in MYC are presumed to play a role.

De novo chronic lymphocytic leukemia/prolymphocytic leukemia or B-cell prolymphocytic leukemia? The importance of integrating clinico-morphological and immunophenotypic findings in distinguishing chronic lymphoproliferative diseases with circulating phase

B-cell prolymphocytic leukemia (B-PLL) is an extremely rare disease, accounting for approximately 1% of the lymphocytic leukemias. B-PLL generally occurs in older people. It is characterized by the presence of more than 55% prolymphocytes in the peripheral blood (PB), no or minimal lymphadenopathy, massive splenomegaly, and very high white blood cell counts. The prognosis of B-PLL patients is generally poor, with a median survival of 3 years, although a subset of patients may show a prolonged survival. Herein, we report a case of a 70-year-old male with weakness, generalized lymphadenopathy, and moderate splenomegaly at the initial presentation. Hematologic examination revealed lymphocytic leukocytosis, favoring a chronic lymphoproliferative disorder (CLPD). The key to decoding the precise CLPD was a combination of the clinical profile, morphologic findings on the peripheral blood and the bone marrow, immunophenotypic analysis, and cytogenetic study. The best diagnosis proffered was a de novo chronic lymphocytic leukemia/prolymphocytic leukemia. There was no prior history of lymphoproliferative disorder or lymphocytic leukocytosis. Discriminating this entity from other lymphoproliferative disorders is crucial as the treatment and prognosis are varied compared to the other lymphoproliferative disorders. The diagnostic conundrum encountered and the incredible utility of ancillary studies in such a scenario are highlighted in this study.

T-cell neoplasms in the spleen

Hematopoietic neoplasms involving the spleen are uncommon, but T cell neoplasms involving the spleen are extremely rare. The rarity of splenic involvement by T cell neoplasms has resulted in a limited body of literature describing their splenic characteristics. As a result, our purpose in this review article is to provide and summarize some of the characteristics seen by different T cell neoplasms that may involve the spleen.

Effective upfront treatment with low-dose ibrutinib for a patient with B cell prolymphocytic leukemia

B cell prolymphocytic leukemia (B-PLL) is a rare and aggressive disease that is associated with poor survival. Although initially asymptomatic patients do not require therapy, most patients will progress and inevitably require treatment. More than 50% of patients with B-PLL carry abnormalities in the TP53 tumor suppressor gene and/or complex karyotype and show resistance to conventional chemotherapy. The efficacy of ibrutinib, a B cell receptor inhibitor, for B-PLL with the TP53 abnormality as second-line therapy was recently demonstrated. We herein report that low-dose ibrutinib as upfront therapy induced a complete response in a B-PLL patient with the TP53 abnormality, whose condition has since remained stable with no recurrence for 12 months. Effective treatments for B-PLL are lacking and given its rarity, prospective comparative therapies are not yet available. This case suggests that upfront therapy with ibrutinib improves the outcome of B-PLL.

Consensus criteria for diagnosis, staging, and treatment response assessment of T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare, mature T-cell neoplasm with a heterogeneous clinical course. With the advent of novel treatment options that will potentially change the management of patients with T-PLL, it has become necessary to produce consensus guidelines for the design and conduct of clinical trials. The T-PLL International Study group (TPLL-ISG) set out to define standardized criteria for diagnosis, treatment indication, and evaluation of response. These criteria will facilitate comparison of results from clinical trials in T-PLL, and will thus support clinical decision making, as well as the approval of new therapeutics by healthcare authorities.

B-cell Prolymphocytic Leukemia: Case Report and Challenges on a Diagnostic and Therapeutic Forefront

B-cell prolymphocytic leukemia (B-PLL) is a rare malignancy of mature B-cells with characteristic morphologic, immunophenotypic, cytogenetic, and molecular features characterized by late onset (median age 69 years), an aggressive clinical course, refractoriness to chemotherapy, and median survival of around three years. Treatment is influenced by the presence or absence of specific high-risk genetic mutations like 17P/TP53 deletion, the presence of which translates into poor prognosis. Patients without 17P deletion, who are <70 years, without significant co-morbidities, are initially treated with a combination chemotherapy regimen used for chronic lymphocytic leukemia (CLL) such as fludarabine, cyclophosphamide, and rituximab. On the other hand, patients with a 17P deletion, age >70 years, with multiple co-morbidities, receive ibrutinib or alemtuzumab as the initial therapy. Relapsed or refractory cases are managed with BCL-2 signaling inhibitors like venetoclax. We discuss the case of an 84-year-old male with B-PLL (positive TP53 mutation), resistant to ibrutinib therapy, with extremely high white blood cell (WBC) counts, thus creating a dilemma regarding the best treatment in the second-line setting.

Sequential Kinase Inhibition (Idelalisib/Ibrutinib) Induces Clinical Remission in B-Cell Prolymphocytic Leukemia Harboring a 17p Deletion

B-cell prolymphocytic leukemia (B-PLL) is a rare lymphoid neoplasm with an aggressive clinical course. Treatment strategies for B-PLL remain to be established, and, until recently, alemtuzumab was the only effective therapeutic option in patients harboring 17p deletions. Herein, we describe, for the first time, a case of B-cell prolymphocytic leukemia harboring a 17p deletion in a 48-year-old man that was successfully treated sequentially with idelalisib-rituximab/ibrutinib followed by allogeneic hematopoietic stem cell transplant (allo-HSCT). After 5 months of therapy with idelalisib-rituximab, clinical remission was achieved, but the development of severe diarrhea led to its discontinuation. Subsequently, the patient was treated for 2 months with ibrutinib and the quality of the response was maintained with no severe adverse effects reported. A reduced-intensity conditioning allo-HSCT from a HLA-matched unrelated donor was performed, and, thereafter, the patient has been in complete remission for 10 months now. In conclusion, given the poor prognosis of B-PLL and the lack of effective treatment modalities, the findings here suggest that both ibrutinib and idelalisib should be considered as upfront therapy of B-PLL and as a bridge to allo-HSCT.

A case report of T cell prolymphocytic leukemia and Kaposi sarcoma and a review of T cell prolymphocytic leukemia

T cell prolymphocytic leukemia (T-PLL) is a rare mature T cell lymphoproliferative disease. It has been associated with an aggressive course, a poor response to conventional chemotherapy and a short median survival. Here we present a rare case of concurrent T-PLL and Kaposi sarcoma who achieved a complete hematologic and cytogenetic remission after a very short course of treatment with alemtuzumab. A review of T-PLL was done. In this review, clinical features, laboratory features and current therapeutic strategies of T-PLL are presented.

Paired box gene 5 may modulate Proviral Integration of Moloney virus 2 gene and protein expression in mature B-cells

Deregulated transcription factor Paired box gene 5 (Pax-5) expression has been implicated in B-cell lymphoma in human disease. Proviral Integration of Moloney virus 2 (Pim-2) kinase may play a role in apoptosis and chemotherapy resistance. We characterized the expression of Pax-5 and Pim-2 in mature B-cell lines and 293T cells transfected with human isoforms of Pax-5. By quantitative real-time polymerase chain reaction (qRT-PCR), we showed that Pax-5 isoforms significantly increased Pim-2 mRNA expression in 293T cells and that mRNAs for both Pax-5 and Pim-2 were two-fold significantly expressed in mature malignant B-cells. Western blot analysis showed that Pim-2 protein expression was increased in 293T cells transiently transfected with human isoforms of Pax-5 and that Pax-5 isoforms and Pim-2 proteins were expressed in mature B-cell lines. By electrophoretic mobility shift analysis, we showed that Pax-5 isoforms were able to bind to the Pim-2 promoter region. Taken together, these results suggest that Pax-5 may act as a transcription factor to modulate the expression of Pim-2 and that both proteins may play a role in the oncogenesis of mature B-cell lymphoma.

T-cell large granular lymphocyte leukemia associated with myelodysplastic syndrome: a clinicopathologic study of nine cases

We describe 9 patients with T-cell large granular lymphocyte leukemia (T-LGL) who also had a myelodysplastic syndrome (MDS). There were 6 men and 3 women with a median age of 60 years (range, 25-74 years). All patients had anemia at initial examination, 7 had neutropenia, and 5 had thrombocytopenia. The median absolute lymphocyte count was 1,300/microL (1.3 x 10(9)/L; range, 700-3,600/microL [0.7-3.6 x 10(9)/L]). Immunophenotypic analysis showed a CD8+ T-cell population, and molecular analysis showed monoclonal T-cell receptor gene rearrangement in every case. The MDS was classified as refractory cytopenia with multilineage dysplasia (RCMD, n = 5), refractory anemia (n = 2), RCMD with ringed sideroblasts (n = 1), and chronic myelomonocytic leukemia (n = 1). We compared the data for these patients with T-LGL/MDS with a group that had only T-LGL. The median hemoglobin level and absolute lymphocyte count were lower in patients with T-LGL/MDS (P < .05). The frequency of coexistent T-LGL and MDS at our institution suggests an etiologic relationship rather than simple coincidence.

Emerging drugs for rarer chronic lymphoid leukemias

BACKGROUND

Rarer indolent lymphoid leukemias include well defined mature B-cell and T-cell neoplasm with widely varying natural history and specific morphological, immunophenotypic and molecular characteristics. Among these are prolymphocytic leukemia (PLL), hairy cell leukemia (HCL) and its variants, large granular lymphocyte leukemia (LGLL) and adult T-cell leukemia/lymphoma (ATLL).

OBJECTIVE

To present current therapies and emerging drugs potentially useful in the treatment of rarer chronic lymphoid leukemias.

METHODS

After searching MEDLINE, PubMed and the Current Contents database, and conference proceedings from the previous 3 years of the American Society of Hematology (ASH), the European Society of Hematology (EHA) and the American Society of Clinical Oncology (ASCO) were searched manually; articles written in English and additional relevant publications were then selected.

RESULTS/CONCLUSION

New drugs including monoclonal antibodies (mAbs), new purine analogs, small molecules targeting specific molecular targets and other agents are included. Future research should focus on the novel therapeutic strategies based on the molecular pathogenic mechanisms and the development of new targeted therapies for each distinct chronic lymphoid leukemia.

T-cell large granular lymphocytic (T-LGL) leukemia: experience in a single institution over 8 years

T-cell large granular lymphocytic (T-LGL) leukemia is characterized by cytopenia and clonal proliferation of large granular lymphocytes. We identified 26 patients with T-LGL leukemia seen at our institution over a period of 8 years. The majority of the patients were asymptomatic at diagnosis. Nine patients were treated with cyclosporine; one achieved a complete remission, and four had a hematological response. Other treatment modalities included single agent alemtuzumab, alemtuzumab combined with pentostatin, fludarabine, and combination of fludarabine and cyclophosphamide. Significant responses were not seen with any of these treatment regimens. We conclude that cyclosporine therapy may be beneficial for T-LGL leukemia patients. New treatment modalities are needed for these patients.