Therapy of chronic lymphocytic leukaemia with purine nucleoside analogues: facts and controversies

Pneumonia in Transplant Recipients: A Comprehensive Review of Diagnosis and Management

Transplant recipients have an increased risk of complications, including graft dysfunction and infections, which can be life-threatening if not recognized early. Pneumonia ranks as one of the most frequent complications in both solid organ and hematopoietic stem cell transplants. Clinical symptoms manifest late during infections in immunocompromised patients. An aggressive approach centered on early confirmatory diagnosis and a low threshold for empiric therapy is often the most effective strategy. The isolation of a pathogen in an upper airway sample does not necessarily mean the same organism is responsible for pneumonia. Viruses such as CMV (cytomegalovirus virus) may function as co-pathogens for opportunistic infections in transplant recipients in addition to causing their own primary infectious syndrome. Furthermore, some viruses exhibit immunomodulatory effects that can affect the graft function. Given the exhaustive list of causative pathogens responsible for pneumonia, the best approach to the diagnosis is to have a conceptual framework that includes a detailed history, such as the type of transplant, degree of immunosuppression, antimicrobial prophylaxis, risk factors, time of presentation since transplantation and the radiographic pattern on the CT chest (computer tomography of the chest). Management depends predominantly on the degree of antimicrobial resistance, drug-to-drug interaction, and adjustments to the immunosuppression.

A decade of chronic lymphocytic leukaemia therapy in Germany: Real-world treatment patterns and outcomes (2010-2022)

Pharmacotherapy options for chronic lymphocytic leukaemia (CLL) have expanded significantly in recent years. These options include chemotherapy, chemoimmunotherapy and signalling pathway inhibitors. A notable shift in the treatment landscape began with the widespread adoption of ibrutinib in 2016. This analysis of claims data focuses on understanding how the use of novel therapies has evolved in clinical practice over the past decade in Germany. Anonymized claims data (2010-2022) from German statutory health insurance was used, covering patient demographics, treatments, and prescriptions. The study population included patients with two confirmed CLL diagnoses. Treatment patterns were analysed, and survival outcomes were compared using time-to-event analyses. In the analysed cohort of 2983 incident CLL patients, 1041 started first-line therapy between 2011 and 2022, with a median duration of 18 months from diagnosis to the first prescription. Chemoimmunotherapy, the predominant 1L therapy until 2019, decreased significantly, while targeted therapy usage increased from 3% in 2015 to 77% in 2022. Targeted therapies became dominant in patients receiving treatment for relapsed or refractory disease after 2016. Median treatment durations were: 122 days for chemo, 176 days for chemo-immuno, and 373 days for targeted therapy. The overall survival for patients diagnosed in or after 2016 was significantly better (hazard ratio 0.56, 95% confidence interval, 0.44-0.69)). The adoption of targeted therapies like ibrutinib and venetoclax has transformed CLL treatment in Germany, leading to improved patient outcomes. Additionally, we demonstrate successful adherence to evolving clinical guidelines.

Cutaneous manifestations of B-cell chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a malignant lymphoproliferative disease characterized by the accumulation of immature monoclonal B lymphocytes in blood cells, bone marrow, spleen and lymph nodes. This is the most common type of leukemia among the Caucasoid race. When CLL skin lesions occur in about 25% of patients, they are extremely diverse. These lesions can be divided into specific, including infiltration of the skin by leukemic cells and the skin form of Richter's syndrome, secondary skin tumors, nonspecific lesions and associated skin diseases.Leukemic infiltration of the skin in patients with leukemia is called specific skin lesions (SSL). Many authors associate the unfavorable prognosis with the transformation of CLL with specific infiltration of the skin into Richter syndrome, as well as the appearance of SSL before the diagnosis of CLL. The risk of developing various cancer pathologies in patients with CLL is three times higher than in healthy people identical in sex and age. It was found that the risk of skin cancer in these patients is eight times higher than in the healthy population. The most common secondary skin tumors in CLL are basal-cell carcinoma, squamous-cell carcinoma, melanoma, and Merkel tumor.Nonspecific skin changes are extremely diverse and occur in patients with CLL in 30-50% of cases. The most common secondary changes in the skin in CLL are those of infectious nature. There are also increased reactions to insect bites, generalized itching, exfoliative erythroderma, nodular erythema, paraneoplastic pemphigoid, bullous pemphigoid, drug eruption. Concomitant dermatoses in these patients are more severe and often torpid to the previously conducted therapy. There is no doubt that together with the clarification of the etiology and pathogenesis of CLL, particular issues related to the study of clinical and morphological changes in individual organs and systems, in particular the skin, formed at various stages of the development of this disease should be studied in detail. This can not only expand and clarify our understanding of this pathology, but also can help to clarify the essence of the disease.

Targeted Therapy in Chronic Lymphocytic Leukemia

Despite a prevailing view that advances in cancer therapy will come through selective targeting of enzymes encoded by mutated oncogenes responsible for the neoplastic phenotype, recent advances in the treatment of patients with chronic lymphocytic leukemia (CLL) have instead exploited knowledge of its biology. Indeed, CLL cells depend on interactions with cells and soluble factors present in the tumor microenvironment for proliferation and survival. B-cell receptor signaling and chemokine-receptor signaling play prominent roles. Elucidation of these signaling pathways has defined physiologic targets for drugs, such as ibrutinib, which inhibit Bruton tyrosine kinase and are therapeutically effective. The characteristic high-level expression of BCL2 in CLL that can enhance leukemia-cell survival has now become an Achilles heel targeted by clinically effective drugs such as venetoclax. Here we discuss advances in such targeted therapy and highlight other disease attributes, such as the distinctive expression of ROR1, which may be targeted for clinical benefit, alone or in combination with other targeted therapies.

Chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is a malignancy of CD5+ B cells that is characterized by the accumulation of small, mature-appearing lymphocytes in the blood, marrow and lymphoid tissues. Signalling via surface immunoglobulin, which constitutes the major part of the B cell receptor, and several genetic alterations play a part in CLL pathogenesis, in addition to interactions between CLL cells and other cell types, such as stromal cells, T cells and nurse-like cells in the lymph nodes. The clinical progression of CLL is heterogeneous and ranges from patients who require treatment soon after diagnosis to others who do not require therapy for many years, if at all. Several factors, including the immunoglobulin heavy-chain variable region gene (IGHV) mutational status, genomic changes, patient age and the presence of comorbidities, should be considered when defining the optimal management strategies, which include chemotherapy, chemoimmunotherapy and/or drugs targeting B cell receptor signalling or inhibitors of apoptosis, such as BCL-2. Research on the biology of CLL has profoundly enhanced our ability to identify patients who are at higher risk for disease progression and our capacity to treat patients with drugs that selectively target distinctive phenotypic or physiological features of CLL. How these and other advances have shaped our current understanding and treatment of patients with CLL is the subject of this Primer.

Cutaneous Richter syndrome: a better place to transform?

The development of high-grade lymphoma in patients with chronic lymphocytic leukaemia is known as Richter syndrome (RS) and is associated with a grave prognosis, with a mean survival of 8 months despite treatment. Cutaneous RS has been described in a handful of cases and may be associated with a better outcome than the more common extracutaneous variants. We review the literature with particular emphasis on pathogenesis, treatment and survival of RS. We postulate that the absence of B symptoms and a normal lactate dehydrogenase level, presumably reflecting localized or limited disease, and a lower tumour burden, may explain the apparently better survival in some patients with cutaneous RS than with extracutaneous variants.

Hypoxia-induced deoxycytidine kinase expression contributes to apoptosis in chronic lung disease

Chronic obstructive pulmonary disease (COPD) is characterized by persistent inflammation and tissue remodeling and is a leading cause of death in the United States. Increased apoptosis of pulmonary epithelial cells is thought to play a role in COPD development and progression. Identification of signaling pathways resulting in increased apoptosis in COPD can be used in the development of novel therapeutic interventions. Deoxyadenosine (dAdo) is a DNA breakdown product that amplifies lymphocyte apoptosis by being phosphorylated to deoxyadenosine triphosphate (dATP). dAdo is maintained at low levels by adenosine deaminase (ADA). This study demonstrated that mice lacking ADA developed COPD manifestations in association with elevated dAdo and dATP levels and increased apoptosis in the lung. Deoxycitidine kinase (DCK), a major enzyme for dAdo phosphorylation, was up-regulated in mouse and human airway epithelial cells in association with air-space enlargement. Hypoxia was identified as a novel regulator of DCK, and inhibition of DCK resulted in diminished dAdo-mediated apoptosis in the lungs. Our results suggest that activating the dAdo-DCK-dATP pathway directly results in increased apoptosis in the lungs of mice with air-space enlargement and suggests a novel therapeutic target for the treatment of COPD.

Two novel aspirin analogues show selective cytotoxicity in primary chronic lymphocytic leukaemia cells that is associated with dual inhibition of Rel A and COX-2

OBJECTIVES

Non-steroidal anti-inflammatory drugs have been shown to induce apoptosis in primary B-cell chronic lymphocytic leukaemia (CLL) cells, but the molecular mechanisms that underpin this observation have not been fully elucidated. Here, we have analysed the effect two novel aspirin analogues, 2-hydroxy benzoate zinc (2HBZ) and 4-hydroxy benzoate zinc (4HBZ), on primary CLL samples.

MATERIALS AND METHODS

Cytotoxic effects of 2HBZ and 4HBZ were analysed in primary CLL cells derived from 52 patients, and normal B- and T-lymphocytes. Mechanisms of action of these agents were also elucidated.

RESULTS

Both analogues induced apoptosis in a dose-dependent and time-dependent manner. Apoptosis was associated with activation of caspase-3 that could be partially abrogated by the caspase-9 inhibitor (Z-LEHD.fmk). Importantly, both agents demonstrated preferential cytotoxicity in CLL cells when compared to normal B- and T-lymphocytes. In terms of their molecular mechanisms of action, 4HBZ and 2HBZ inhibited COX-2 transcription and protein expression and this was associated with upstream inhibition of transcription factor Rel A. Co-culture of CLL cells with CD40 ligand-expressing mouse fibroblasts significantly increased COX-2 expression and inhibited spontaneous apoptosis. Importantly, the most potent analogue, 4HBZ, overcame pro-survival effects of the co-culture system and significantly repressed COX-2. Finally, elevated COX-2 expression was associated with poor prognostic subsets and increased sensitivity to 4HBZ.

CONCLUSIONS

Our results demonstrate therapeutic potential of 4HBZ and are consistent with a mechanism involving suppression of Rel A nuclear translocation and inhibition of COX-2 transcription.

Nucleoside analogs induce proteasomal down-regulation of p21 in chronic lymphocytic leukemia cell lines

Nucleoside analogs (NAs) represent an important class of anticancer agents that induce cell death after conversion to triphosphate derivatives. One of their most important mechanisms of action is the activation of p53, leading to apoptosis through the intrinsic pathway. Classically, the activation of p53 also induces p21 accumulation, which leads to cell cycle arrest at the G1/S transition. In previous work, we observed that 2-chloro-2'-deoxyadenosine (CdA), a NA with high activity in lymphoid disorders, including chronic lymphocytic leukemia (CLL), promotes the G1/S transition in the CLL cell line EHEB at cytotoxic concentrations. This finding led us to investigate the p21 response to NAs in these cells. We show here that CdA, but also fludarabine, gemcitabine, and cytarabine, strongly reduced the p21 protein level in EHEB cells as well as in JVM-2 cells, another CLL cell line. This p21 depletion occurred despite induction of p53 and increase of p21 mRNA and was prevented by proteasome inhibitors. Increase of proteasomal degradation caused by NAs appeared to be ubiquitin-independent. Also, NAs induced in these cells an increase of cyclin-dependent kinase (Cdk2) activity and a monoubiquitination of cell proliferating nuclear antigen (PCNA), two processes that are negatively regulated by p21. These changes were not observed with other p53 activators, like etoposide and nutlin-3a that increased the p21 protein level. In conclusion, our study reveals that NAs can induce an alternative pattern of cellular response in some cell models.

Human nucleoside transporters: biomarkers for response to nucleoside drugs

This review describes recent advances in developing human nucleoside transporters (hNTs) as biomarkers to predict response to nucleoside analog drugs with clinical activity. Understanding processes that contribute to drug response or lack thereof will provide strategies to potentiate efficacy or avoid toxicities of nucleoside analog drugs. hNT abundance, evaluated by immunohistochemical methods, has shown promise as a predictive marker to assess clinical drug response that could be used to identify patients who would most likely benefit from nucleoside analog drug treatment.

Skin lesions in chronic lymphocytic leukemia

Cutaneous lesions occur in up to 25% of patients with chronic lymphocytic leukemia (CLL). These can be caused by either cutaneous seeding by leukemic cells (leukemia cutis, LC) and other malignant diseases or nonmalignant disorders. Skin infiltration with B-lymphocyte CLL manifests as solitary, grouped, or generalized papules, plaques, nodules, or large tumors. Prognosis in CLL patients with LC is rather good and many authors claim that it does not significantly affect patients' survival. However, prognosis is poor in patients in whom LC shows blastic transformation (Richter's syndrome) and when leukemic infiltrations in the skin appear after the diagnosis of CLL. Secondary cutaneous malignancies are also frequent complications in patients with CLL. A higher risk was seen in skin cancer, for which eightfold higher occurrence has been stated. There are some suggestions that alkylating agents and purine analogs may be associated with an increased incidence of secondary malignancies in CLL. Nonspecific, secondary cutaneous lesions are frequently observed in CLL patients. The most common secondary cutaneous changes seen in CLL are those of infectious or hemorrhagic origin. Other secondary lesions present as vasculitis, purpura, generalized pruritus, exfoliative erythroderma, and paraneoplastic pemphigus. An exaggerated reaction to an insect bite and insect bite-like reactions have been also observed.

Current and emerging treatments for chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common adult leukaemia in Europe and North America. The disease is characterized by proliferation and accumulation of small CD5+ B cells in blood, lymph nodes, spleen, liver and bone marrow. The natural clinical course of CLL is highly variable, and chemotherapy is usually not indicated in early and stable disease. However, patients with progressive and more advanced CLL require treatment. For many years, chlorambucil with or without corticosteroids was used in previously untreated patients with CLL. More recently, purine nucleoside analogues (PNAs) [fludarabine, cladribine and pentostatin] have been included in treatment approaches for this disease, and chlorambucil is no longer the leading standard everywhere. Currently, this drug is rather recommended for the treatment of older, unfit patients with co-morbidities, especially in European countries. Significantly higher overall response (OR) and complete response (CR) rates in patients treated initially with PNAs than in those treated with chlorambucil or cyclophosphamide-based combination regimens have been confirmed in randomized, prospective, multicentre trials. Moreover, PNAs administered in combination with cyclophosphamide produce higher response rates, including CR and molecular CR, compared with PNA as monotherapy. Recent reports suggest that the administration of monoclonal antibodies (mAbs) can significantly improve the course of CLL. At present, two mAbs have the most important clinical value in patients with CLL. The first is rituximab, a human mouse antibody that targets CD20 antigens, and the second is alemtuzumab, a humanized form of a rat antibody active against CD52. Several recent reports suggest that in patients with CLL, rituximab combined with a PNA can increase the OR and CR rates compared with PNA or rituximab alone, with acceptable toxicity. In randomized trials, the combination of rituximab with fludarabine and cyclophosphamide (FC-R regimen) demonstrated higher rates of OR, CR and progression-free survival in patients with previously untreated and relapsed or refractory CLL than fludarabine plus cyclophosphamide (FC regimen). Several reports have confirmed significant activity with alemtuzumab in relapsed or refractory CLL, as well as in previously untreated patients. Recently, several new agents have been investigated and have shown promise in treating patients with CLL. These treatments include new mAbs, agents targeting the antiapoptotic bcl-2 family of proteins and receptors involved in mediating survival signals from the microenvironment, antisense oligonucleotides and other agents. The most promising are new mAbs directed against the CD20 molecule, lumiliximab and anti-CD40 mAbs. Oblimersen, alvocidib (flavopiridol) and lenalidomide are also being evaluated both in preclinical studies and in early clinical trials. In recent years, a significant improvement in haematopoietic stem cell transplantation (HSCT) procedures in patients with high-risk CLL has been observed. However, the exact role of HSCT, autologous or allogeneic, in the standard management of CLL patients is still undefined.

Chapter 2: Ring-Expanded (‘Fat‘) Purines and their Nucleoside/Nucleotide Analogues as Broad-Spectrum Therapeutics

This chapter describes a family of ring-expanded purines, informally referred to as “fat” or f-purines, as well as their nucleoside/nucleotide analogues (RENs/RENTs) that have broad applications in chemistry, biology, and medicine. Although purine itself has never been found in nature, substituted purines, such as adenine and guanine, or their respective nucleoside derivatives, adenosine and guanosine, are the most ubiquitous class of nitrogen heterocycles and play crucial roles in wide variety of functions of living beings As nucleotides (AMP,GMP), they are the building blocks of nucleic acids (RNA/DNA). They serve as energy cofactors (ATP, GTP), as part of coenzymes (NAD/FAD) in oxidation-reduction reactions, as important second messengers in many intracellular signal transduction processes (cAMP/cGMP), or as direct neurotransmitters by binding to purinergic receptors (adenosine receptors). Therefore, it is not surprising that the analogues of purines have found utility both as chemotherapeutics (antiviral, antibiotic, and anticancer agents) and pharmacodynamic entities (the regulation of myocardial oxygen consumption and cardiac blood flow). While they can act as substrates or the inhibitors of the enzymes of purine metabolism to render their chemotherapeutic action, their ability to act as agonists or antagonists of A1/A2A receptors is the basis for the modulation of pharmacodynamic property.

Immunohistochemistry for human concentrative nucleoside transporter 3 protein predicts fludarabine sensitivity in chronic lymphocytic leukemia

Fludarabine (F-ara-A) is widely used as palliative treatment in chronic lymphocytic leukemia (CLL). Clinical resistance is frequently observed, and adverse effects are common. To date, no practical assay exists to identify patients likely to derive benefit from F-ara-A. We previously reported that high mRNA levels encoding human concentrative nucleoside transporter 3 (hCNT3) protein in CLL correlated with clinical resistance to F-ara-A. This study explores the value of immunohistochemistry (IHC) for hCNT3 as a marker of F-ara-A resistance in CLL. We studied 36 CLL patients who received F-ara-A monotherapy and had suitable pre-F-ara-A tissue available. IHC was performed with validated hCNT3-specific monoclonal antibodies and quantitatively scored by a hematopathologist blinded to clinical outcomes. Relationships between hCNT3 staining in CLL cells and time to progression (TTP), overall response (OR), and overall survival (OS) were assessed. Dichotomization of quantitative hCNT3 staining showed that subjects with high hCNT3 IHC scores had a significantly shorter TTP with F-ara-A treatment compared to those with a low score (hazard ratio, HR, 3.16; P=0.006). Median TTP was 4.7 vs 11.2 months, respectively. On multivariate analysis, hCNT3 score was the only clinical parameter independently associated with TTP (HR, 3.12; P=0.01). OR and OS did not differ significantly between the dichotomized groups. We found a strong relationship between IHC staining of hCNT3 and clinical resistance to F-ara-A therapy in CLL. If confirmed, IHC for hCNT3 may be routinely used to predict those patients unlikely to benefit from F-ara-A, thereby avoiding F-ara-A-related toxicities.

Rituximab plus cladribine with or without cyclophosphamide in patients with relapsed or refractory chronic lymphocytic leukemia

OBJECTIVES

The aim of our study was to determine the feasibility, effectiveness and toxicity of combined regimens consisting of rituximab and cladribine (2-CdA) (RC) and RC plus cyclophosphamide (RCC) in the treatment of patients with recurrent or refractory chronic lymphocytic leukemia (CLL).

METHODS

The RC regimen consisted of rituximab given on day 1 and 2-CdA (days 2-6). The RCC protocol included rituximab (day 1), 2-CdA (days 2-4) and cyclophosphamide given on days 2-4. The courses were re-administered at time intervals of 4 weeks or longer if severe myelosuppression occurred.

RESULTS

Forty-six patients with CLL entered the study. Eighteen patients were treated with RC and 28 with RCC regimen. The median number of courses administered were three cycles (range 1-6). Three (6.5%) patients (95% CI: 1-14%) achieved a complete response and 31 (67%) patients (95% CI: 50-83%) a partial response. According to the particular regimen, the overall response rate was obtained in 12 (67%) patients treated with RC (95% CI: 45-89%) and in 22 patients (78%) treated with RCC (95% CI: 62-93%). The median progression free survival of responders to RC/RCC regimens was 12 months (range 4-46). Hypersensitivity to rituximab occurred in 16 (33%) patients, mostly during the first infusion of the drug. Grade 3/4 neutropenia was seen in six (13%) patients, grade 3/4 thrombocytopenia in three (9%) patients and grade 3/4 infections were observed in ten (28%) patients.

CONCLUSIONS

These data indicate that both RC and RCC regimens are feasible in heavily pretreated patients with CLL, showing also distinct therapeutic activity and relatively low toxicity, even in patients previously treated with cladribine-based protocols.

Malignant lymphomas in the elderly: A single institute experience highlights future directions

In this study, our experience with the diagnostics and treatment of malignant lymphoma patients were analyzed, with a special consideration of the elderly. Between 1980 and 2005, there were 181 cases found (35%) among 517 non-Hodgkin's lymphoma (NHL) patients and 46 cases (8.1%) among 565 Hodgkin's lymphoma (HL) patients, who were at least 65 years old at the time of diagnosis. Comparing elderly patients to young ones, the time from first symptoms to diagnosis was significantly longer (NHL: 7.6 months versus 4.1 months, HL: 11.4 months versus 5.6 months). B-cell and indolent NHL-s were more common (92.8% versus 79.2% and 56.4% versus 35.1%) such as classical lymphocyte predominant (cLP) HL-s (30.4% versus 15.0%); however nodular sclerosis (NS) HL-s occurred less frequently (10.9% versus 32.2%). Stages were more advanced and comorbidity was more common. Primary therapies were more often inappropriate (NHL: 20.4% versus 5.1%, HL: 26.0% versus 6.0%); there were more complications, but less cases with complete remission (NHL: 17.1% versus 61.1%, HL: 63.0% versus 79.2%) and dose reductions were more commonly applied (NHL: 46.7% versus 17.2%, HL: 52.9% versus 11.3%). Remission rates were significantly worsened by dose reductions (NHL: 68.5% versus 34.5%, HL: 61.8% versus 44.4%). Appropriate therapies resulted in significantly better overall survival (OS) rates (log-rank<0.05). It can be concluded that more favourable results can be achieved in the remission and survival rates of elderly malignant lymphoma patients if the appropriate curative or palliative therapies, considering new and less toxic protocols such as supportive care, are chosen.

The role of nucleoside transporters in cancer chemotherapy with nucleoside drugs

Nucleoside analogs are important components of treatment regimens for various malignancies. Nucleoside-specific membrane transporters mediate plasma membrane permeation of physiologic nucleosides and most nucleoside analogs, for which the initial event is cellular conversion of nucleosides to active agents. Understanding of the roles of nucleoside transporters in nucleoside drug toxicity and resistance will provide opportunities for potentiating anticancer efficacy and avoiding resistance. Because transportability is a possible determinant of toxicity and resistance of many nucleoside analogs, nucleoside transporter abundance might be a prognostic marker to assess drug resistance. Elucidation of the structural determinants of nucleoside analogs for interaction with transporter proteins as well as the structural features of transporter proteins required for permeant interaction and translocation will lead to "transportability guidelines" for the rational design and therapeutic application of nucleoside analogs as anticancer drugs. It should eventually be possible to develop clinical assays that predict sensitivity and/or resistance to nucleoside anti-cancer drugs and thus to identify those patient populations that will most likely benefit from optimal nucleoside analog treatments. This review discusses recent results from structure/function studies of human nucleoside transporters, the role of nucleoside transport processes in the cytotoxicity and resistance of several anticancer nucleoside analogs and strategies to improve the nucleoside transporter-related anticancer effects of nucleoside analogs.

Presence of the anti-leukemic nucleotide analog, 2-chloro-2'-deoxyadenosine-5'-monophosphate, in a promoter sequence alters DNA binding of TATA-binding protein (TBP)

2-Chlorodeoxyadenosine (CldAdo, Cladribine), a nucleoside analog used in the treatment of hairy cell leukemia, is phosphorylated and incorporated into DNA, but is not an absolute chain terminator. We hypothesized that the presence of a chlorine molecule projecting into the DNA minor groove would affect DNA:protein-binding interactions. Here, we investigated recognition of and binding to double-stranded CldAMP-substituted TATA promoter sequences by human TATA-binding protein (TBP) using mobility shift assays. Depending on the site, CldAMP in place of dAMP within a TATA sequence decreased in vitro TBP binding by approximately 30% to 55% compared to control sites. When bound to a CldAMP-substituted TATA box, however, the TBP complex was more resistant to polyanions, suggesting enhanced stability. Limited exposure of the TBP:DNA complex to proteases indicated that TBP conformation was altered on CldAMP-substituted DNA compared to control. Further, binding of transcription factor IIB to TBP was diminished on analog-containing TATA sequences. These results suggest normal TBP-binding interactions--specifically recognition, stability, and conformation-are disrupted by CldAMP insertion into eukaryotic promoter sequences.

Rituximab combined with cladribine or with cladribine and cyclophosphamide in heavily pretreated patients with indolent lymphoproliferative disorders and mantle cell lymphoma

BACKGROUND

In vitro studies have shown synergistic or additive interactions between rituximab and purine nucleoside analogues. The results of recent clinical trials seem to confirm these preclinical observations.

METHODS

For the current study, the authors evaluated the feasibility, efficacy, and toxicity of combined regimens that consisted of either rituximab plus cladribine (2-CdA) (the RC regimen) or RC plus cyclophosphamide (the RCC regimen) in the treatment of patients with heavily pretreated, indolent lymphoid malignancies. Fifty-four adult patients with recurrent or refractory, low-grade non-Hodgkin lymphoma (LG-NHL) and B-cell chronic lymphocytic leukemia (B-CLL) were treated according to the RC/RCC regimens. The RC protocol consisted of intravenous rituximab at a dose of 375 mg/m(2) on Day 1 and 2-CdA at a dose of .12 mg/kg per day on Days 2 through 6. The RCC protocol consisted of rituximab at a dose of 375 mg/m(2) on Day 1, 2-CdA at a dose of 0.12 mg/m(2) on Days 2 through 4, and intravenous cyclophosphamide at a dose of 250 mg/m(2) per day on Days 2 to 4. The RC/RCC courses were repeated at 4-week intervals.

RESULTS

Thirty-three patients with B-CLL, 12 patients with LG-NHL and 9 patients with mantle cell lymphoma (MCL) entered the study. Thirty-three patients (61%) had recurrent disease after prior therapy, and 21 patients (39%) had refractory disease. Thirty-one patients were treated on the RC regimen, and 23 patients were treated on the RCC regimen. Six patients (11%) achieved a complete response, and 33 patients (60%) achieved a partial response. The median failure-free survival of responders was 10.5 months. The treatment revealed tolerability, with episodes of severe neutropenia (Grade 3 and 4 [according to World Health Organization criteria]) observed in 6 patients (11%), episodes of Grade 3 and 4 infections observed in 11 patients (20%), and episodes of Grade 3-4 thrombocytopenia observed in 4 patients (7%).

CONCLUSIONS

The RC and RCC regimens were highly effective and well tolerated modalities of treatment in heavily pretreated patients with indolent lymphoproliferative disorders.