Detection of tumor-specific antigens in Philadelphia chromosome positive leukemias

Continuing pursuit for ideal systemic anticancer radiotherapeutics

Cancer is one of the major causes of death for non-transmissible chronic diseases worldwide. Conventional treatments including surgery, chemotherapy and external beam radiotherapy are generally far from curative. Complementary therapies are attempted for achieving more successful treatment response. Systemic targeted radiotherapy (STR) is a radiotherapeutic modality based on systemic administration of radioactive agents for selectively delivering high doses of energy to destroy cancer cells. For this purpose, diverse tumour-target specific agents including monoclonal antibodies (MoAb), MoAb fragments and peptides have been tested and some of them have already got FDA approval for clinical use. However, MoAbs and their tailored analogues have shown non-homogeneous tumour distribution, limited diffusion, insufficient intratumoral accumulation and retention, unwanted uptake in normal tissues and scarcity of identified cancer antigens for generating new MoAbs. Similarly, peptides have also exhibited retention in normal organs, lacks of favourable membrane permeability or drug cell internalization and short-term residence in cancer cells. Recently, a new category of target-specific agent with strong affinity for necrosis has emerged as an excellent option for developing targeted radiotherapeutic agents to be used after necrosis-inducing treatments (NITs). The combination of their high, specific and long-term accumulation and retention at necrotic sites with the crossfire effect of ionizing particle-emitters allows irradiating adjacent residual viable tumour cells during a prolonged period of time. It may considerably enhance the therapeutic response and open a new horizon for improved cancer treatability or curability.

Autologous immune strategies to reduce the risk of leukemic relapse: Consideration for IL-15

The graft-versus-leukemia effect following allogeneic stem cell transplantation (SCT) reduces the incidence of leukemic relapse and establishes that effector cells can eliminate or at least contain resistant leukemic stem cells. Natural killer cells also appear to play a role in directly lowering the rate of relapse following allogeneic SCT in patients with acute myeloid leukemia. To date, however, effective prevention of leukemic relapse by autologous immune effector cells has not been demonstrated. This article examines some of the challenges that limit autologous antileukemia immunity as well as some possible immunotherapeutic approaches that may help control leukemic relapse following autologous SCT.

Expression of bcr-abl mRNA in individual chronic myelogenous leukaemia cells as determined by in situ amplification

We present the results of a novel method developed for evaluation of in situ amplification, a molecular genetic method at the cellular level. Reverse transcription polymerase chain reaction (RT-PCR) was used to study bcr-abl transcript levels in individual cells from patients with chronic myelogenous leukaemia (CML). After hybridizing a fluorochrome-labelled probe to the cell-bound RT-PCR product, bcr-abl mRNA-positive cells were determined using image analysis. A dilution series of bcr-abl-positive BV173 into normal cells showed a good correlation between expected and actual values. In 25 CML samples, the percentage of in situ PCR-positive cells showed an excellent correlation with cytogenetic results (r = 0.94, P < 0.0001), interphase fluorescence in situ hybridization (FISH) (r = 0.95, P = 0.001) and hypermetaphase FISH (r = 0.81, P < 0.001). The fluorescence intensity was higher in residual CML cells after interferon (IFN) treatment than in newly diagnosed patients (P = 0.004), and was highest in late-stage CML resistant to IFN therapy and lowest in CML blast crisis (P = 0.001). Mean fluorescence values correlated with bcr-abl protein levels, as determined by Western blot analysis (r = 0.62). Laser scanning cytometry allowing automated analysis of large numbers of cells confirmed the results. Thus, fluorescence in situ PCR provides a novel and quantitative approach for monitoring tumour load and bcr-abl transcript levels in CML.

Calcium signaling induces acquisition of dendritic cell characteristics in chronic myelogenous leukemia myeloid progenitor cells

Effective host T lymphocyte sensitization to malignant cells depends on successful antigen presentation. In this study, we examined the capacity of malignant myeloid progenitor cells of patients in the chronic phase of chronic myelogenous leukemia (CML) to acquire characteristics of activated dendritic cells (DCs) after intracellular calcium mobilization, thereby bypassing a need for third-party antigen-presenting cells. Treatment of purified CD33(+) CML cells from 15 patients with calcium ionophore (CI) consistently resulted in de novo expression of the costimulatory molecules CD80 (B7.1) and CD86 (B7.2), CD40 and the DC-specific activation marker CD83, as well as marked up-regulation of MHC class I and II molecules and the adhesion molecule CD54. Most of these changes occurred within 24 hr of treatment. Morphologically, CI-treated CML cells developed long dendritic projections similar to those seen in mature DCs. Functionally, CI-treated CML cells provided stimulation of allogeneic T lymphocytes 10- to 20-fold that of untreated CML cells or untreated monocytes. Fluorescent in situ hybridization of CI-activated CML cells confirmed their leukemic origin by displaying the typical bcr/abl fusion signal. No difference in bcr/abl translocation percentages between untreated and CI-treated CML nuclei was observed. These observations indicate that calcium mobilization may constitute a valuable approach for rapidly and reliably generating CML-derived DCs for immunotherapy of CML.

Does the type of BCR/ABL junction predict the survival of patients with Ph1-positive chronic myeloid leukemia?

The prognostic value of the site of DNA rearrangement within the M-BCR on chromosome 22 or of the type of transcript has been debated in the last years. The majority of the studies do not support the hypothesis of a predictive value of such molecular parameters. Results coming from a multicentric, prospective trial, based on alpha-IFN therapy, seem to indicate a better karyotypic response in 3' rearranged patients. The possibility of evoking a cytotoxic immune response directed towards peptides originating from each of the different BCR/ABL junctions constitute an important challenge for the future.