Reduced-dose fludarabine, cyclophosphamide, and rituximab (FCR-Lite) plus lenalidomide, followed by lenalidomide consolidation/maintenance, in previously untreated chronic lymphocytic leukemia.

Fludarabine, cyclophosphamide, and rituximab (FCR) remains the standard of care for fit chronic lymphocytic leukemia (CLL) patients requiring first therapy. However, side effects can be significant, and patients with poor risk features have inferior outcomes. The purpose of this study was to evaluate reduced-dose FCR (FCR-Lite) plus lenalidomide (FCR(2) ) followed by lenalidomide maintenance as a strategy to shorten immunochemotherapy in untreated CLL. Patients received four to six cycles of FCR(2) . Patients who were minimal residual disease (MRD) negative in peripheral blood (PB) and bone marrow (BM) initiated 12 months of lenalidomide maintenance after either four or six cycles (based on MRD status). The primary study endpoint was the complete response (CR) rate after four cycles of FCR(2) . Twenty patients were evaluable. After four cycles of FCR(2) , response rates were: CR, 45.0%; CR with incomplete blood count recovery (CRi), 5.0%; partial response (PR), 45.0%; and stable disease (SD), 5.0%. BM and PB samples from 27.8% and 52.9% of patients, respectively, were MRD negative. After six cycles, response rates were: CR, 58.3%; CRi, 16.7%; and PR, 25.0%. BM and PB samples from 50.0% and 72.7% of patients, respectively, were MRD negative. Overall, 75% of evaluable patients achieved a CR or CRi following FCR(2) . After 17.4 months of median follow-up, one progression and one death occurred. Our findings suggest that FCR(2) combines encouraging clinical activity with acceptable toxicity in previously untreated CLL. Lenalidomide can be safely added to FCR and may reduce chemotherapy exposure without compromising outcomes.

Phase 1/2 study of ocaratuzumab, an Fc-engineered humanized anti-CD20 monoclonal antibody, in low-affinity FcγRIIIa patients with previously treated follicular lymphoma.

This phase 2 study assessed the safety and efficacy of ocaratuzumab, a humanized anti-CD20 monoclonal antibody. Fifty patients with previously treated follicular lymphoma (FL) and a low-affinity genotype of FcγRIIIa received ocaratuzumab 375 mg/m(2) weekly for 4 weeks. Grade 3/4/5 adverse events (AEs) were reported in 11/1/1 patients, respectively. Serious AEs were reported by 11/50 patients, and three discontinued due to AEs. One patient died from aspiration pneumonia due to possibly drug-related nausea and vomiting. Investigator-assessed response rate was 30% (15/50), including four complete responses (CR), three CR unconfirmed (CRu) and eight partial responses (PR). Investigator-assessed median Progression-free survivial (PFS) was 38.3 weeks. Ocaratuzumab's pharmacokinetic profile was similar to that reported for rituximab. Lymphocyte subset analysis showed significant, selective reduction of B-cells during and after ocaratuzumab treatment. Ocaratuzumab at this dose and schedule is active and well tolerated in patients with previously treated FL with low affinity FcγRIIIa genotypes. ClinTrials registry number: NCT00354926.

A phase 2 study of belinostat (PXD101) in patients with relapsed or refractory acute myeloid leukemia or patients over the age of 60 with newly diagnosed acute myeloid leukemia: a California Cancer Consortium Study.

We performed a phase II study of belinostat in patients with acute myeloid leukemia (AML). In this open label phase II study (NCT00357032), patients with relapsed/refractory AML, or newly diagnosed patients with AML over the age of 60, were eligible. Belinostat was administered intravenously (IV) at a dose of 1000 mg/m(2) daily on days 1-5 of a 21-day cycle until progression or unacceptable toxicity. The primary endpoint was complete response (CR) rate, with secondary endpoints of overall response rate (CR + partial response [PR]), time to treatment failure (TTF), overall survival and safety. Twelve eligible patients with AML were enrolled, of whom six had received at least one prior line of therapy. No CR or PR was seen. Four patients had stable disease for at least five cycles. Grade 3 non-hematological toxicities occurred in four patients. Belinostat as monotherapy has minimal single-agent effect in AML on this dosing schedule.

Novel therapies for aggressive B-cell lymphoma.

Aggressive B-cell lymphoma (BCL) comprises a heterogeneous group of malignancies, including diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma, and mantle cell lymphoma (MCL). DLBCL, with its 3 subtypes, is the most common type of lymphoma. Advances in chemoimmunotherapy have substantially improved disease control. However, depending on the subtype, patients with DLBCL still exhibit substantially different survival rates. In MCL, a mature B-cell lymphoma, the addition of rituximab to conventional chemotherapy regimens has increased response rates, but not survival. Burkitt lymphoma, the most aggressive BCL, is characterized by a high proliferative index and requires more intensive chemotherapy regimens than DLBCL. Hence, there is a need for more effective therapies for all three diseases. Increased understanding of the molecular features of aggressive BCL has led to the development of a range of novel therapies, many of which target the tumor in a tailored manner and are summarized in this paper.

The B lineage transcription factor E2A regulates apoptosis in chronic lymphocytic leukemia (CLL) cells.

Chronic lymphocytic leukemia (CLL) is a common malignancy characterized by the accumulation of B lymphocytes with an antigen-experienced activated CD19(+)CD5(+) clonal phenotype. Clinically, ∼50% of cases will behave more aggressively. Here, we investigate the role of the major B-cell transcription factor E2A, a known regulator of B-cell survival and proliferation, to CLL persistence. We show that E2A is elevated at the mRNA and protein levels relative to normal B-cell subsets. E2A silencing in primary CLL cells leads to a significant increase in spontaneous apoptosis in both CD38(+) (aggressive) and CD38(-) (indolent) cases. Moreover, E2A knockdown synergizes with the immunomodulatory drug lenalidomide to reduce CLL viability. E2A is known to restrain the proliferation of primary B and T lymphocytes at multiple stages of maturation and we report that targeted E2A disruption increases the frequency of Ki-67(+) CLL cells in the absence of effects on de novo proliferation. At the molecular level, E2A siRNA-treated CLL cells display reduced expression of key genes associated with survival and cell cycling including p27, p21 and mcl-1, of which the former two are known E2A target genes. Thus, E2A, a key transcription factor associated with the B-cell activation profile, regulates apoptosis in CLL and may contribute to disease pathology.

Fludarabine and cytarabine in patients with acute myeloid leukemia refractory to two different courses of front-line chemotherapy.

The most effective regimen for acute myeloid leukemia (AML) patients who do not achieve complete remission (CR) after two different courses of front-line chemotherapy has not been established. We therefore evaluated the efficacy, toxicity, and prognostic factors for achieving CR following treatment with fludarabine and cytarabine in 25 newly diagnosed AML patients who did not respond to initial therapy with idarubicin and cytarabine followed by mitoxantrone and etoposide. CR was achieved in 32% of patients; in 55% of patients with intermediate-risk karyotype and in 14% with unfavorable-risk. Eight percent died of infectious complications. Median duration of overall survival was 6.6 months (95% CI 3.4 months to ∞); 3.4 months (95% CI 0.8-8.6 months) for patients with an unfavorable-risk karyotype and 18.1 months (95% CI 5.0 months to ∞) with an intermediate-risk karyotype (p=0.02). Our data suggest that poor-risk karyotype patients are unlikely to benefit from third course treatment with fludarabine-cytarabine, and that this regimen merits further investigation in AML patients with good or intermediate-risk karyotype that have persistent leukemia after two courses of front-line chemotherapy.

Comparative analysis of MVA-CD40L and MVA-TRICOM vectors for enhancing the immunogenicity of chronic lymphocytic leukemia (CLL) cells.

Adenoviral transduction with CD40L and poxviral transduction with B7-1, ICAM-1, and LFA-3 (TRICOM) have been used to enhance the antigen-presenting capacity of chronic lymphocytic leukemia (CLL) cells. This study compares the same vector (modified vaccinia virus strain Ankara (MVA)) encoding CD40L or TRICOM for its ability to enhance the immunogenicity of CLL cells. CLL cells from some patients showed differential responses to each vector in terms of induction of autologous T-cell responses. This study supports the rationale for the use of CLL cells modified ex vivo with pre-specified recombinant MVA vectors as a whole tumor-cell vaccine for immunotherapy in CLL patients.

Interleukin-15 enhances natural killer cell cytotoxicity in patients with acute myeloid leukemia by upregulating the activating NK cell receptors.

Interleukin-15 (IL-15) has a major role in NK-cell homeostasis. Modulation of the relative frequency and expression intensity of the NK-cell receptors by IL-15 may increase NK cell-mediated cytotoxicity in cancer patients. We investigated the receptor repertoire and measured NK-cell activity in newly diagnosed AML patients and evaluated the ex vivo effects of IL-15. The expression of the activating NK cell receptors was significantly decreased in the AML patients compared to that in NK cells of healthy donors. When NK cells obtained from AML patients were cultured with IL-15, expression of the activating receptors was significantly upregulated compared to pre-culture levels. Concomitantly, cytotoxic activity of NK cells against autologous leukemic blasts increased following IL-15 stimulation. This IL-15 induced increase in activity was blocked by neutralizing antibodies specific for the NK cell activating receptors. These pre-clinical data support the future use of IL-15 for NK cell- based therapies for AML patients.

Increased frequency and suppression by regulatory T cells in patients with acute myelogenous leukemia.

PURPOSE: Regulatory CD4(+)CD25(high)Foxp3(+) T cells (Treg) control peripheral immune tolerance. Patients with cancer, including those with hematologic malignancies, have elevated numbers of Treg in the peripheral circulation and in tumor tissues. However, mechanisms of suppression and clinical significance of Treg, especially in patients with acute myelogenous leukemia (AML), has not been well defined. EXPERIMENTAL DESIGN: We prospectively evaluated the phenotype, function, and mechanisms of suppression used by Treg in newly diagnosed untreated AML patients. The relationship between the frequency of circulating Treg and the disease status as well as treatment outcome was also evaluated. RESULTS: The percentage of circulating Treg was higher (P < 0.0001) and their phenotype was distinct in AML patients relative to normal controls. Suppression mediated by Treg coincubated with proliferating autologous responder cells was also higher (P < 0.001) in AML than that mediated by control Treg. Using Transwell inserts, we showed that interleukin-10 and transforming growth factor-beta1 production as well as cell-to-cell contact were necessary for Treg-mediated suppression. Also, the pretreatment Treg frequency predicted response to chemotherapy. Unexpectedly, patients who achieved complete remission still had elevated frequency of Treg, which mediated high levels of suppressor activity. CONCLUSIONS: Treg accumulating in the peripheral circulation of AML patients mediate vigorous suppression via contact-dependent and contact-independent mechanisms. Patients with lower Treg frequency at diagnosis have a better response to induction chemotherapy. During the post-induction period, the Treg frequency and suppressive activity remain elevated in complete remission, suggesting that Treg are resistant to conventional chemotherapy.

Stimulatory effects of CpG oligodeoxynucleotide on dendritic cell-based immunotherapy of colon cancer in CEA/HLA-A2 transgenic mice.

Immunostimulatory DNA containing unmethylated cytosine-guanine (CpG) motifs have been successfully used as adjuvants to enhance the immunity of vaccines designed to trigger antitumor T-cell responses. We examined the effect of a CpG oligodeoxynucleotide (CpG ODN) for its ability to potentiate the activity of tumor antigen-pulsed dendritic cells (DC) in a clinically relevant mouse model, which is transgenic for both carcinoembryonic antigen (CEA) and HLA-A2 for the treatment of colon carcinoma in a therapeutic setting. The systemic administration of CpG ODN 1826 alone had modest effect on tumor growth when tumors were palpable and had no effect with larger tumor burden. However, coadministration of CpG ODN 1826 with the vaccine provided significant increase in tumor-free survival compared with mice immunized with DC-based vaccines alone. The DC/CpG combined vaccination strategy resulted in increased secretion of Th1 cytokines and HLA-A2-restricted CEA-specific CTL responses were also enhanced. Both tumor regression and extended tumor-free survival resulting from DC/CpG combination therapy required the participation of T cells. Tumor-free mice were resistant to tumor rechallenge and immunity conferred by the vaccine was transferable in athymic nude mice. These results provide evidence that vaccination with antigen-pulsed DC with CpG ODN as adjuvant can lead to effective tumor regression and long-term survival in a murine model of colon carcinoma.

Chronic lymphocytic leukemia (CLL) cells genetically modified to express B7-1, ICAM-1, and LFA-3 confer APC capacity to T cells from CLL patients.

In chronic lymphocytic leukemia (CLL), malignant B cells and nonmalignant T cells exhibit dysfunction. We previously demonstrated that infection of CLL cells with modified vaccinia Ankara (MVA) expressing the costimulatory molecules B7-1, ICAM-1, and LFA-3 (designated TRICOM) increased expression of these costimulatory molecules on the surface of CLL cells and thus augmented their antigen-presenting capability. Here, we evaluate the effect of MVA-TRICOM-modified CLL cells on T cells. Following incubation with irradiated MVA-TRICOM-modified CLL cells, allogeneic and autologous CD4(+) and CD8(+) T cells expressed significantly higher levels of B7-1, ICAM-1, and LFA-3. We show that this increase was the result of physical acquisition from the antigen-presenting cells (APCs), and that purified T cells that acquired costimulatory molecules from MVA-TRICOM-modified CLL cells were able to stimulate the proliferation of untreated T cells. These results demonstrate for the first time that T cells from CLL patients can acquire multiple costimulatory molecules from autologous CLL cells and can then act as APCs themselves. Given the immunodeficiencies characteristic of CLL, enhancing the antigen-presenting function of CLL cells and T cells simultaneously could be a distinct advantage in the effort to elicit antitumor immune responses.

Chemoimmunotherapy with low-dose fludarabine and cyclophosphamide and high dose rituximab in previously untreated patients with chronic lymphocytic leukemia.

PURPOSE: Chemoimmunotherapy combining fludarabine, cyclophosphamide, and rituximab (FCR) is an active regimen for untreated patients with chronic lymphocytic leukemia (CLL) with 70% complete responses (CRs) and 95% overall responses (ORs). However, grade 3/4 neutropenia was reported in 52% of cycles of treatment. The purpose of this trial was to maintain the high responses but reduce the toxicity of FCR by decreasing the fludarabine and cyclophosphamide (FCR-Lite). PATIENTS AND METHODS: We conducted a single arm study of FCR-Lite which includes maintenance rituximab in 50 untreated CLL patients. Patients were evaluated for response using both the 1996 National Cancer Institute Working Group (NCIWG) guidelines and the 2008 guidelines. Two thirds of patients were treated by community physicians. RESULTS: The median age was 58 years (range, 36 to 85 years); 20 patients had Rai stage 1, 22 had Rai stage 2, and eight had Rai stage 3 and 4. The OR and CR rates were 100% and 79%, respectively, using the 1996 NCIWG guidelines and 100% and 77% using the 2008 guidelines. Median duration of complete response was 22.3 months (range, 5.2 to 42.5 months) and none of the complete responders have relapsed. Grade 3/4 neutropenia was noted in 13% of the cycles of therapy. CONCLUSION: FCR-Lite is highly effective in previously untreated CLL patients. Grade 3/4 neutropenia was dramatically reduced compared to standard FCR and our data demonstrated FCR-Lite can be safely administered in the community setting.

Phase II trial of short-course CHOP-R followed by 90Y-ibritumomab tiuxetan and extended rituximab in previously untreated follicular lymphoma.

PURPOSE: Radioimmunotherapy has been approved for relapsed follicular lymphoma (FL), including rituximab-refractory FL. This study was designed to determine the CR rate with short-course chemoimmunotherapy with cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab (CHOP-R) followed by 90-Y ibritumomab tiuxetan (RIT) with extended rituximab as first-line treatment. EXPERIMENTAL DESIGN: Between March 2004 and February 2007, 60 patients with stage II to IV symptomatic or bulky FL from a single institution supported by a large community network entered this phase II trial. Patients received CHOP-R for three treatment cycles before RIT followed by four additional weekly treatments with rituximab. Response was determined using fusion [(18) F] fluorodeoxyglucose-positron emission tomography (PET)-computed tomography (CT) imaging. RESULTS: Of the 60 patients entering this trial, 55 patients completed all protocol therapy. The median follow up was 19.7 months (range, 0.26-35.9 months). For intent-to-treat analysis, the complete response (CR) rate after CHOP-R, as assessed by CT and PET imaging, was 40% and 46%, respectively. After RIT, the CR rate improved, as assessed by CT and PET imaging, to 82% and 89%, respectively. Ten patients have progressed, including eight from best response of CR. Seven of 18 patients who were PET positive after CHOP-R progressed compared with 3 of 37 patients who were PET negative (P=0.010). CONCLUSIONS: In patients with previously untreated, symptomatic or bulky FL, short-course chemoimmunotherapy and consolidation RIT and extended rituximab resulted in a high CR rate. Failure to achieve an early PET CR after CHOP-R indicated high risk of relapse.

Approved monoclonal antibodies for cancer therapy.

BACKGROUND: Monoclonal antibodies are a rapidly expanding class of agents for the treatment of cancer. In 1997 rituximab became the first approved monoclonal antibody for the treatment of low grade B cell lymphoma. Since then several monoclonal antibodies have received approval from the United States Food and Drug Administration (US FDA) for the treatment of a variety of solid tumors and hematological malignancies. OBJECTIVE/METHODS: To review the literature using Medline and summarize the mechanisms of action, indications and outcome of treatment of currently approved monoclonal antibodies used in clinical practice for patients with solid tumors and hematologic malignancies. RESULTS/CONCLUSIONS: An overview of the FDA approved monoclonal antibodies is provided. Monoclonal antibodies are currently used as the standard of care as first and second line therapy for a number of hematologic malignancies and solid tumors. Over the next 5 - 10 years additional monoclonal antibodies and monoclonal antibody conjugates will be approved by the US FDA and will dramatically affect the standard of care of many cancers.

Carcinoembryonic antigen transgenic mouse models for immunotherapy and development of cancer vaccines.

The goal of cancer therapy remains as the long-term eradication of tumor cells without adverse effects on normal tissue. Conventional approaches utilizing chemotherapy and radiotherapy are limited by both their toxicity and lack of specificity. In recent years, investigators have carried out several studies designed to evaluate whether human tumor-associated antigens (TAAs) can be exploited as targets for immunotherapy, specifically for human cancer vaccine development. A major limitation in immunotherapy studies of human cancer is the general lack of appropriate preclinical models. Clinical studies can be difficult to implement, particularly when a clear understanding of the potential efficacy, limitation, and safety of an immunotherapeutic strategy is not available from relevant animal investigations. However, mice carrying a transgene for a human tumor self-antigen may provide a more acceptable experimental model in which knowledge about immunotherapeutic strategies aiming at the TAA of interest can be enhanced prior to initiating clinical trials. Since the different strategies in experimental immunotherapy of cancer have been directed to activate different immune system components, a variety of transgenic mouse models have been generated expressing either TAA, human leukocyte antigen (HLA), oncogene, or immune effector cell molecules. These models may serve as an excellent platform for the identification of novel targets for immunotherapy as well as to evaluate the efficacy of targeted therapies and will lead to the development of clinical trials for cancer patients. In this unit, a brief overview of the generation and study of different vaccine approaches in carcinoembryonic antigen (CEA) transgenic mouse models and the experimental findings in mouse models that spontaneously develop gastrointestinal tumors and express the CEA transgene is provided.

Type 1-polarized dendritic cells loaded with autologous tumor are a potent immunogen against chronic lymphocytic leukemia.

Induction of active tumor-specific immunity in patients with chronic lymphocytic leukemia (CLL) and other hematologic malignancies is compromised by the deficit of endogenous dendritic cells (DCs). In attempt to develop improved vaccination strategies for patients with CLL and other tumors with poorly identified rejection antigens, we tested the ability of ex vivo-generated DCs to cross-present the antigens expressed by CLL cells and to induce CLL-specific, functional CTL responses. Monocyte-derived DCs from CLL patients were induced to mature using a "standard" cytokine cocktail (in IL-1beta, TNF-alpha, IL-6, and PGE2) or using an alpha-type 1-polarized DC (alphaDC1) cocktail (in IL-1beta, TNF-alpha, IFN-alpha, IFN-gamma, and polyinosinic:polycytidylic acid) and were loaded with gamma-irradiated, autologous CLL cells. alphaDC1 from CLL patients expressed substantially higher levels of multiple costimulatory molecules (CD83, CD86, CD80, CD11c, and CD40) than standard DCs (sDCs) and immature DCs, and their expression of CCR7 showed intermediate level. alphaDC1 secreted substantially higher (10-60 times) levels of IL-12p70 than sDCs. Although alphaDC1 and sDCs showed similar uptake of CLL cells, alphaDC1 induced much higher numbers (range, 2.4-38 times) of functional CD8+ T cells against CLL cells. The current demonstration that autologous tumor-loaded alphaDC1 are potent inducers of CLL-specific T cells helps to develop improved immunotherapies of CLL.

Flow cytometric immunophenotyping for hematologic neoplasms.

Flow cytometric immunophenotyping remains an indispensable tool for the diagnosis, classification, staging, and monitoring of hematologic neoplasms. The last 10 years have seen advances in flow cytometry instrumentation and availability of an expanded range of antibodies and fluorochromes that have improved our ability to identify different normal cell populations and recognize phenotypic aberrancies, even when present in a small proportion of the cells analyzed. Phenotypically abnormal populations have been documented in many hematologic neoplasms, including lymphoma, chronic lymphoid leukemias, plasma cell neoplasms, acute leukemia, paroxysmal nocturnal hemoglobinuria, mast cell disease, myelodysplastic syndromes, and myeloproliferative disorders. The past decade has also seen refinement of the criteria used to identify distinct disease entities with widespread adoption of the 2001 World Health Organization (WHO) classification. This classification endorses a multiparametric approach to diagnosis and outlines the morphologic, immunophenotypic, and genotypic features characteristic of each disease entity. When should flow cytometric immunophenotyping be applied? The recent Bethesda International Consensus Conference on flow cytometric immunophenotypic analysis of hematolymphoid neoplasms made recommendations on the medical indications for flow cytometric testing. This review discusses how flow cytometric testing is currently applied in these clinical situations and how the information obtained can be used to direct other testing.