Biomedical subjects
Publications and source records attributed to Claire Dearden.
Hairy cell leukemia is a rare B-cell neoplasm. When treated with either pentostatin or cladribine, complete and durable remissions can be secured and life expectancy for most patients is normal. A small minority of patients require alternative treatment with monoclonal antibodies or immunotoxins. Patients who attain a complete response to first-line treatment have the best prognosis.
T and B subtypes of prolymphocytic leukemias (PLLs) are rare, highly aggressive lymphoid malignancies with characteristic morphologic, immunophenotypical, cytogenetic, and molecular features. Recent studies have highlighted the role of specific oncogenes such as TCL1, MTCP-1, and ATM in the case of T-cell and p53 mutations in the case of B-cell PLLs. Despite the advances in the understanding of the biology of these conditions, prognosis for these patients remains poor with short survival and no curative treatment. The advent of monoclonal antibody therapy has improved treatment options for this group. In particular, the use of Campath-1H, in T-PLL has more than doubled median survival. The role of allogeneic transplant with nonmyeloablative conditioning needs to be explored further.
T-cell malignancies are rare, making up 10% to 15% of all lymphoid neoplasms in adults. They include many different types of disorders such as T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia, adult T-cell leukemia/lymphoma, cutaneous T-cell lymphoma, and peripheral T-cell lymphoma, which are themselves divided into multiple subcategories. Most T-cell malignancies arise as a result of chromosomal abnormalities, including T-cell receptor rearrangement anomalies. Viral infections are implicated in the development of adult T-cell leukemia/lymphoma and some cases of peripheral T-cell lymphoma have been linked to Epstein-Barr virus or human immunodeficiency virus infection. With the possible exception of T-cell large granular lymphocytic leukemia, which often has an indolent course, T-cell malignancies have not responded well to conventional chemotherapeutic treatment. The introduction of monoclonal antibodies for the treatment of cancer has changed the outlook for patients with T-cell malignancies. Recent studies with single-agent alemtuzumab, an anti-CD52 monoclonal antibody, have shown improved response rates and survival in patients with T-cell prolymphocytic leukemia and cutaneous T-cell lymphoma. Preliminary data also suggest that alemtuzumab may have activity in patients with heavily pretreated peripheral T-cell lymphoma who are refractory to conventional chemotherapy. Preclinical studies with mice bearing human adult T-cell leukemia/lymphoma cells suggest that alemtuzumab may have a potential therapeutic role in this setting. Treatment of T-cell hematologic malignancies with alemtuzumab appears promising. Earlier treatment and combination with chemotherapeutic agents may improve treatment outcome for patients with these malignancies and allow for consolidation with stem cell transplant strategies in selected patients.
We report a high incidence of myelodysplastic syndrome (MDS)/acute myeloid leukaemia (AML) in patients entered into the preceding Medical Research Council Chronic Lymphocytic Leukaemia Pilot study of autografting [corrected] Of 115 newly diagnosed patients treated with fludarabine, 65 patients proceeded to autologous transplant. Conditioning was cyclophosphamide and total body irradiation in 49 (75%) patients and chemotherapy in 12 (18%). Ten patients have developed MDS/AML; eight had undergone an autograft. Five-year actuarial risk of developing MDS/AML postautograft was 12.4% (95% confidence interval, 2.5-24%). No analysed potential risk factor was predictive for MDS/AML development. We hypothesise that potential causative factors are fludarabine, low cell dose and transplant conditioning.
BACKGROUND: Both pentostatin and cladribine have efficacy in hairy cell leukemia (HCL), but it is not known which agent achieves better results. METHODS: We reviewed a series of 219 patients with HCL, with median follow-up from diagnosis of 12.5 years (range 1.0 -34.6 yrs), treated with either pentostatin (n = 185) or cladribine (n = 34), to compare these agents and assess the potential for cure. RESULTS: Overall response to pentostatin was 96% with a complete response (CR) in 81% and a median disease-free survival (DFS) of 15 years. Response to first-line cladribine was 100% with a CR in 82% and DFS of 11+ years. The relapse rates at 5 years and 10 years were 24% and 42%, respectively, with pentostatin, and 33% and 48% with cladribine. Survival at 10 years was respectively 96% and 100%. CR rates decreased with each sequential relapse through 69% to 45% (P < or = 0.001). Patients achieving CR after first-line treatment had a significantly longer DFS (P = 0.00007) than those achieving a partial response; a similar result was seen after second-line therapy (P = 0.00001). DFS also declined with sequential treatment (P = 0.00005). CONCLUSION: We have shown equivalent efficacies for both agents in the treatment of HCL, with DFS showing no plateau. True cure in HCL remains elusive, but the addition of monoclonal antibodies may be beneficial. Our results suggest that achieving CR should remain the main goal of treatment.
Mature T-cell and NK-cell leukemias are a group of relatively uncommon neoplasms derived from mature or postthymic T-cells accounting for a relatively small percentage of lymphoid malignancies. The recent availability of modern immunophenotypic and molecular tools has allowed a better distinction of these disorders from their B-cell counterparts. Similarly, identification of recurrent cytogenetic abnormalities, as well as plausible mechanisms through which these molecular events influence cellular signaling pathways, have created further insight into the pathogenesis of these disorders. Furthermore, the availability of new agents such as alemtuzumab has generated significant interest in devising specific therapeutic strategies for these malignancies. Herein, we review the clinical and pathological features of mature T-cell leukemias.
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The effect of pregnancy on T-cell large granular lymphocyte (LGL) leukaemia has not been previously described. We retrospectively reviewed the clinical features of three patients with T-cell LGL leukaemia; each of them had one or more pregnancies during disease evolution. Pregnancy was associated with sustained improvement in neutrophil count and concurrent reduction in lymphocytosis. Neutropenia returned in the non-pregnant state in all cases. A similar effect, induced by exogenous progesterone in one patient, suggests a role for progesterone in overcoming mechanisms of neutropenia in this disease. Pregnancy thus appears to have a beneficial effect on neutrophil count in T-cell LGL leukaemia.
We reviewed the efficacy of alemtuzumab in the treatment of 28 patients with refractory chronic lymphocytic leukemia (CLL) in whom p53 status was known. Overall responses of 53.6% (complete responses 17.9%) were attained with no significant difference between patients with (50%) or without (55%) p53 deletion (p=0.214). We confirm the efficacy of alemtuzumab in refractory CLL irrespective of p53 deletions, and advocate its introduction earlier in disease course.
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The humanized monoclonal antibody CAMPATH-1H (alemtuzumab) binds to the CD52 antigen, a glycoprotein that is widely expressed on normal and malignant B- and T-lymphocytes. Over the past 5 years, a number of trials have demonstrated that alemtuzumab has clinical activity in mature T-cell diseases such as T-cell prolymphocytic leukemia (T-PLL) and cutaneous T-cell lymphoma (CTCL). In heavily pretreated relapsed/refractory patients alemtuzumab induced responses in more than two thirds of T-PLL and more than 50% of CTCL patients. Responding patients had improved survival compared to nonresponders. Alemtuzumab is particularly effective in clearing malignant lymphocytes from peripheral blood and bone marrow and may therefore facilitate stem-cell transplantation (SCT) in selected patients. The toxicity profile for the antibody is acceptable; the major complications are infusional reactions, which generally subside after the first 1-2 weeks of therapy, and prolonged lymphopenia associated with reactivation of viruses. These can be minimized by careful monitoring and the use of prophylactic therapy. Future studies will be directed toward: alternative routes (subcutaneous) and schedules of administration; use as first-line therapy; combination strategies with conventional chemotherapy; and use of alemtuzumab to purge minimal residual bone-marrow disease prior to SCT.
An expert opinion roundtable held August 8-9, 2002, brought together clinicians with the most extensive experience with the use of alemtuzumab to pool knowledge and develop treatment goals and guidelines for optimal therapy. By sharing our collective experience, we have been able to formulate recommendations for current clinical practice, which are included in this report, and have emphasized results that have implications for future practice. Guidelines for the management of acute "first-dose" events, prophylaxis for infection, detection and treatment of cytomegalovirus reactivation, and hematologic support are presented, with emphasis on allowing patients to proceed smoothly through therapy while maximizing therapeutic benefit. Management of adverse events is facilitated by the predictable timing of their appearance. In general, hematologic adverse events are transient, manageable, and reversible. Clinicians should be cautious of prematurely terminating treatment at 4-6 weeks in patients whose disease responds to treatment. Although resolution of peripheral blood lymphocytosis occurs early in most patients, bone marrow is unlikely to be clear of disease. In particular, grade 4 neutropenia at this time is common and, because it is manageable, it is not an indication to discontinue treatment. The eradication of minimal residual disease from blood and bone marrow observed with alemtuzumab therapy is a major step forward in the treatment of B-cell chronic lymphocytic leukemia. Combination therapies such as alemtuzumab/fludarabine with the potential to maximize eradication at all disease sites should be systematically investigated. Because high response rates and few complications are observed in previously untreated patients, the use of alemtuzumab earlier in therapy may provide optimum benefit to patients.
Over the past decade the potential for delivering targeted therapy against malignant disease by the use of monoclonal antibodies (MAbs) has begun to be realised. Haematological malignancies, because of the relative accessibility of the malignant cell in blood and bone marrow and the understanding of haemopoietic lineage-specific antigens, have provided a successful testing ground for this therapy. There have been many technical developments which have allowed the safe delivery of more potent antibody constructs. The development of human or chimeric antibodies has largely overcome the problems associated with host immune responses to rodent-derived MAbs. Protein engineering to combine MAbs with other biologically active molecules such as radioisotopes, toxins, chemotherapy and cytokines, has made available a new range of agents with clinical activity. The purpose of this review is not to give a catalogue of all therapeutic antibodies but rather to outline the principles of this approach, the current state of knowledge, and possible directions for future development. First, the general requirements and strategies for use of both unmodified and conjugated MAbs are discussed, followed by a summary of the trial data in specific lymphoid and myeloid haemopoietic malignancies. The focus is on MAbs that now have an accepted use in clinical practice, with some discussion of newer MAbs under development. Vaccination strategies and the role of MAbs in bone marrow transplantation are not discussed in detail. The trials of the next decade will address issues such as: whether clinical activity translates into improved survival; the optimal strategies and timing for clinical use; whether increasing potency of MAbs (as in radio- and immunoconjugates) will increase toxicity and, finally, what other potential molecules, such as those influencing cell growth and death, may be targeted.