Waiting for the "liquid revolution" in the adjuvant treatment of colon cancer patients: a review of ongoing trials.

Since colon cancer has a high rate of shedding of tumour fragments into the blood, several research efforts are now focused on the investigation of the minimal residual disease through the detection of ctDNA to tailor the adjuvant therapy of colon cancer patients and optimize its cost/effectiveness balance. The negative prognostic impact of detectable ctDNA in patients' blood after radical surgery for colon cancer is well established. Several clinical trials adopting heterogeneous designs and techniques are now ongoing to translate promises into daily practice by answering five general questions: i) is a ctDNA-guided decision making efficacious in the post-operative management of colon cancer patients? ii) are de-escalation strategies possible in ctDNA-negative cases? iii) are escalation strategies useful to improve the prognosis of ctDNA-positive patients? iv) when MRD is identified at the end of the adjuvant chemotherapy, is another post-adjuvant systemic therapy efficacious? v) can we exploit ctDNA technologies in the follow up of colon cancer patients? This review focuses on currently ongoing trials and how their results may affect the ctDNA "liquid revolution" of early colon cancer.

An mTOR feedback loop mediates the 'flare' ('rebound') response to MET tyrosine kinase inhibition.

Targeted therapy significantly impairs tumour growth but suffers from limitations, among which the 'flare' ('rebound') effect. Among cancers driven by tyrosine kinase receptors, those relying on alterations of the MET oncogene benefit from treatment by specific inhibitors. Previously, we reported that discontinuation of MET tyrosine kinase receptor inhibition causes 'rebound' activation of the oncogene, with a post-treatment transient hyperphosphorylation phase that culminates into a dramatic increase in cancer cell proliferation. The molecular mechanisms behind the 'MET burst' after treatment cessation are unknown but critically important for patients. Here we identify a positive feedback loop mediated by the AKT/mTOR pathway leading to (a) enhanced MET translation by activating p70S6K and 4EBP1 and (b) MET hyper-phosphorylation by inactivation of the tyrosine-phosphatase PTP1B. The latter effect is due to m-TOR-driven PTP1B phosphorylation of the inhibitory residues Ser50 and Ser378. These data provide in vitro evidence for the use of mTOR inhibitors to prevent the 'flare effect' in MET targeted therapy, with potential applicative ramifications for patient clinical management.

MHC-I-restricted presentation of HIV-1 virion antigens without viral replication.

Dendritic cells and macrophages can process extracellular antigens for presentation by MHC-I molecules. This exogenous pathway may have a crucial role in the activation of CD8+ cytotoxic T lymphocytes during human viral infections. We show here that HIV-1 epitopes derived from incoming virions are presented through the exogenous MHC-I pathway in primary human dendritic cells, and to a lower extent in macrophages, leading to cytotoxic T-lymphocyte activation in the absence of viral protein synthesis. Exogenous antigen presentation required adequate virus-receptor interactions and fusion of viral and cellular membranes. These results provide new insights into how anti-HIV cytotoxic T lymphocytes can be activated and have implications for anti-HIV vaccine design.

Scatter factor-dependent branching morphogenesis: structural and histological features.

Branching morphogenesis is a multi-step process that controls the formation of polarised tubules starting from hollow cysts. Its execution entails a series of rate-limiting events which include reversible disruption of cell polarity, dismantling of intercellular contacts, acquisition of a motile phenotype, stimulation of cell proliferation, and final re-establishment of cell polarity for creation of the definitive structures. Branching morphogenesis takes place physiologically during development, accounting for the establishment of organs endowed with a ramified architecture such as glands, the respiratory tract and the vasculartree. In cancer, aberrant implementation of branching morphogenesis leads to deregulated proliferation, protection from apoptosis and enhanced migratory/invasive properties, which together exacerbate the aggressive features of neoplastic cells. Under both physiological and pathological conditions, branching morphogenesis is mainly accomplished by a family of growth factors known as scatter factors. In this review, we will summarise the current knowledge on the biological and functional roles of scatter factors during branching morphogenesis, with a special emphasis on the phenotypic (structural and histological) consequences of scatter factor activity in different tissues.

[ABO incompatibility and non myeloablative allogeneic stem cell transplantation]. / Incompatibilité ABO et greffe allogénique de cellules souches hématopoïétiques à l'ère des conditionnements non myéloablatifs.

ABO incompatibility is not a barrier for allogeneic hematopoietic stem cell transplantation but is associated with specific complications. Major ABO incompatibility is associated with delayed erythroid engraftment, increased transfusion requirement and cases of pure red cell aplasia. Minor ABO incompatibility may be responsible for acute haemolytic reactions in the first months following transplantation. The widely used non myeloablative conditioning regimens might modify the management of ABO incompatibility. They could favour pure red cell aplasia development in the setting of major ABO mismatch since they are associated with a prolonged persistence of host anti-donor isohemagglutinins after allogeneic hematopoietic stem cell transplantation. In the setting of minor ABO incompatibility, the use of peripheral blood stem cells and the nature of graft-versus-host disease prophylaxis regimen may have an impact on the incidence of haemolytic reactions. In that review, the clinical and therapeutic aspects of ABO incompatibility are studied, especially regarding the impact of the conditioning regimen intensity.

Ets up-regulates MET transcription.

MET, a potentially harmful oncogene controlling invasive growth, is overexpressed in a significant percentage of human cancers. Since amplification of the MET gene occurs only in a fraction of these cases, we investigated the transcriptional mechanisms responsible for up-regulation of the promoter activity. The transcription driven by the 3.1 kbp DNA fragment containing the minimal promoter was studied by 5' progressive deletion analysis. The patterns of MET promoter activity suggest the presence of weak negative and positive elements in the region between 300 and 840 bp upstream to the transcription start site. The region encompassing the first 300 bp strongly up-regulates the promoter. This region contains four putative binding sites for members of the Ets transcription factor family, known to be involved in invasive growth. Transient co-expression of Ets1 resulted in a strong enhancement of the MET promoter activity. Increased expression of the Met protein was observed in cells stably transfected with ETS1. Double stranded oligonucleotides with Ets consensus sequence were used as a 'decoy' to inhibit binding to DNA native sites. They dramatically reduced the amount of Met protein in a human carcinoma cell line overexpressing the oncogene. Interestingly, Met activation induces transcription of ETS1 mRNA, showing that Ets proteins act both upstream and downstream to MET. These data indicate that members of the Ets family promote MET transcription and suggest their contribution to the invasive phenotype through overexpression of MET.

Autologous hematopoietic stem cell transplantation as salvage treatment for advanced B cell chronic lymphocytic leukemia.

Given the generally poor outcome of advanced B cell chronic lymphocytic leukemia, experimental approaches are warranted, especially for younger patients in whom classical treatments have failed. We therefore conducted a prospective single-center study, using polychemotherapy (ESHAP) to prepare patients for hematopoietic stem cell collection and autologous stem cell transplantation as consolidation therapy. Twenty patients entered the study. An adequate response to ESHAP was obtained in 13 patients, and sufficient stem cells for grafting were obtained in eight of the 12 patients who underwent the collection procedure. Six of these grafted patients are alive in complete clinical remission a median of 30 months after transplantation. It should be noted that we were only able to graft 40% of the patients enrolled in this study, either because a new remission could not be obtained or because not enough hematopoietic stem cells could be collected. This argues for stem cell collection as soon as a first remission is obtained, even if the autograft is done later in the course of the disease.

Efficient gene delivery and targeted expression to hepatocytes in vivo by improved lentiviral vectors.

Safe and efficient genetic modification of liver cells could enable new therapies for a variety of hepatic and systemic diseases. Lentiviral vectors are promising tools for in vivo gene delivery. Previous data suggested that recruitment into the cell cycle was required for transduction of hepatocytes in vivo. We developed an improved vector design that enhanced nuclear translocation in target cells and significantly improved gene transfer performance. Using the new vector and a panel of internal promoters, we showed that rat hepatocytes were transduced ex vivo to high frequency without requirement for proliferation. On intravenous administration of vector into adult severe combined immunodeficient (SCID) mice, we found high levels (up to 30%) of transduction of parenchymal and nonparenchymal cells of the liver, integration of the vector genome in liver DNA and stable expression of the marker green fluorescent protein (GFP)-encoding gene without signs of toxicity. Coadministration of vectors and 5'-bromo-2'-deoxyuridine in vivo proved that cell cycling was not required for efficient transduction of hepatocytes. In addition to the liver, the spleen and the bone marrow were transduced effectively by systemic delivery of vector. GFP expression was observed in all these organs when driven by the cytomegalovirus promoter and by the phosphoglycerate kinase gene promoter. Using the promoter of the albumin gene, we could restrict expression to hepatocytes. By a single vector injection into the bloodstream of SCID mice, we achieved therapeutic-range levels of the human clotting factor IX, stable in the plasma for up to 1 year (the longest time tested), indicating the potential efficacy of improved lentiviral vectors for the gene therapy of hemophilias and other diseases.

A phase I/II dose-escalation study of herpes simplex virus type 1 thymidine kinase "suicide" gene therapy for metastatic melanoma. Study Group on Gene Therapy of Metastatic Melanoma.

We performed a dose-escalating phase I/II study of retrovirus-mediated herpes simplex virus type 1 thymidine kinase (HSV-1-TK) suicide gene therapy for metastatic melanoma. HSV-1 TK expression, which specifically sensitizes transduced and bystander cancer cells to ganciclovir (GCV) toxicity, was mediated by one (four patients, first dose step) to three (four patients, second dose step) injections of "M11" retrovirus vector-producing cells in melanoma cutaneous nodules. After a 7-day period allowed for cancer cell transduction, GCV was administered for 14 days. Safety was assessed by clinical and laboratory evaluations, and efficacy was assessed by tumor measurements and histology. M11 doses ranged from 76 to 1247 x 10(6) cells. Treatment-related adverse events were mild and transient, limited to inflammatory skin reactions at injection and fever on repeated injections. Plasma GCV was in the active range (>0.2 microg/ml); transgene was detected by polymerase chain reaction in three of six patients; treated tumor size was moderately affected under GCV as compared with untreated tumors, although 2 weeks after GCV administration important (>50%) treated-tumor necrosis was evidenced on histology in three of eight patients. All patients showed disease progression on long-term follow-up. Thus, M11-mediated HSV-1 TK gene therapy was well tolerated over a wide dose range. The limited tumor response is likely to be related to poor gene transfer efficiency. However, necrosis following GCV administration in transduced tumors indicates a potential for treatment efficacy.

Empty and occupied insertion site of the truncated LINE-1 repeat located in the mouse serum albumin-encoding gene.

Taking advantage of the polymorphism created by the presence or the absence of a LINE-1 repeat in intron 12 of the mouse serum albumin-encoding gene, we sequenced the repeat (Alb-L1Md), as well as the flanking regions in BALB/c DNA. The empty insertion site in a wild-type mouse of the same species Mus domesticus was amplified using PCR and sequenced. The Alb-L1Md was truncated at its 5' end and bordered by two 14-bp repeats, which represented the duplication of the empty insertion site. The absence of mutations in the two direct repeats as well as in the poly(dA) tail suggests that the Alb-L1Md sequence had been inserted very recently. On the basis of the insertion sequence of intron 12 and of the sequence of the consensus L1Md repeat, 5' of the insertion, we discuss a model of integration of full-length L1Md-RNA leading to the truncation of the inserted repeat.

Autologous bone marrow transplantation in relapsed HIV-related non-Hodgkin's lymphoma.

There are few reports of salvage chemotherapy for HIV-related non-Hodgkin's lymphoma (NHL). We report a relapsed HIV-related high-grade NHL which was treated successfully with ESHAP chemotherapy followed by high-dose chemotherapy and autologous bone marrow transplantation (ABMT). ABMT may later have triggered opportunistic infections in this patient.

Detection of malignant B cells in peripheral blood stem cell collections after chemotherapy in patients with multiple myeloma.

Autologous transplantation after high-dose chemo or radiotherapy is now frequently used for the treatment of patients with multiple myeloma (MM). The collection of peripheral blood stem cells (PBSC) has a theoretical advantage over autologous bone marrow collection as the malignant plasmacytic contamination is believed to be lower. However, the extent of B cell contamination in PBSC has not been extensively investigated. Using an immunoglobulin heavy chain gene 'fingerprinting' technique at diagnosis and during apheresis after one cycle of chemotherapy we detected a monoclonal population in 44% of PBSC samples (9 positives in 22 studied). There was no correlation between contamination and sex, age, Durie and Salmon classification, C-reactive protein and albumin. A significant correlation was observed with beta 2 microglobulin serum level (P = 0.02). Twenty one patients were grafted and up to the present, with a mean follow-up of 12 months, 6 patients have relapsed including 4 patients with contaminating B cells. Our results suggest that PBSC contamination, defines a 'poor risk' group of patients, with poor prognosis. However, we could not exclude reinitiation of the disease by plasmacyte stem cells after grafting.

Peripheral blood stem cell collection and autografting in high risk lymphomas.

Peripheral blood stem cells (PBSC) were collected from 29 patients with high risk Hodgkin's disease (n = 3) or non-Hodgkin's lymphoma (n = 26) in partial remission or first sensitive relapse. Patients had either bone marrow involvement or hypoplastic bone marrow. The conditioning regimen prior PBSC collection included amsacrine and cytosine arabinoside (Ara-C) or Ara-C alone. PBSC collection was performed after leukocyte counts reached 1 x 10(9)/1. A good yield was obtained in 23 patients, whereas sufficient numbers of CFU-GM were not obtained in six cases. Twenty-one patients have been transplanted. All patients except one achieved bone marrow engraftment. Eight patients are in complete remission (mean duration 15 months). The estimated 2 years survival rate is 46.4% (CI 25-68%). This procedure would seems a good alternative in poor prognosis lymphomas.

Ex vivo expansion of megakaryocyte precursor cells in autologous stem cell transplantation for relapsed malignant lymphoma.

To evaluate the impact of ex vivo expanded megakaryocyte (MK) progenitors on high-dose chemotherapy-induced thrombocytopenia, we conducted a phase II study in 10 patients with relapsed lymphoma. Two fractions of peripheral blood progenitor cells (PBPC) were cryopreserved, one with enough cells for at least 2 x 10(6) CD34+ cells/kg and a second obtained after CD34+ selection. Ten days before autologous stem cell transplantation, the CD34+ fraction was cultured with MGDF+SCF for 10 days. After BEAM (BCNU, cyclophosphamide, cytarabine, and melphalan) chemotherapy, patients were reinfused with standard PBPC and ex vivo expanded cells. No toxicity was observed after reinfusion. The mean fold expansion was 9.27 for nucleated cells, 2 for CD34+ cells, 676 for CD41+ cells, and 627 for CD61+ cells. The median date of platelet transfusion independence was day 8 (range: 7-12). All patients received at least one platelet transfusion. In conclusion, ex vivo expansion of MK progenitors was feasible and safe, but this procedure did not prevent BEAM-induced thrombocytopenia. Future studies will determine if expansion of higher numbers of CD34+ cells towards the MK-differentiation pathway will translate into a functional effect in terms of shortening of BEAM-induced thrombocytopenia.

Intensive chemotherapy with hematopoietic cell transplantation after ESHAP therapy for relapsed or refractory non-Hodgkin's lymphoma. Results of a single-centre study of 65 patients.

This study was designed to assess the results of protracted courses of ESHAP (etoposide, cytarabine, cisplatin, methylprednisolone) therapy followed by intensive chemotherapy and hematopoietic cell transplantation (IC+HCT) for relapsed or refractory non-Hodgkin's lymphoma (NHL). Treatment consisted of 3 cycles of ESHAP; responsive patients (pts) then received 3 more cycles, and IC+HCT was used for pts in maintained partial (PR) or complete (CR) remission after the sixth ESHAP. Sixty-five pts entered the study. At enrollment, 27 pts had bone marrow (BM) and/or central nervous system (CNS) lymphomatous infiltration. Disease status was primary refractory lymphoma in 41 pts (63 %), and relapse in 24 pts (37 %). Results showed that two pts were not evaluable for the therapeutic response because of early treatment-related death. Thirty-nine (62 %) pts entered PR or CR after 3 cycles of ESHAP. Eleven pts subsequently had disease progression. Twenty-eight pts were in persistent CR or PR after 6 cycles of ESHAP. Refractory pts did not show a different response rate to relapsing pts (chi2= 1.73). Five pts were excluded from IC+HCT because of an inadequate graft or treatment-related toxicity. Twenty-three (35 %) pts completed the procedure. Five pts (22 %) relapsed after IC+HCT. The overall survival rate of the 39 responsive pts is 45 % at 60 months, with a median survival time of 30 months. Median survival among the 35 pts in whom second-line chemotherapy failed is 7.1 months, with a 4-year survival rate of 3 %. Despite the poor prognostic features of this group, 45% of pts responding to the first 3 cycles of chemotherapy are in prolonged remission, suggesting that rather than to transplant after just 2 cycles of salvage therapy, pursuing second-line chemotherapy may better discriminate between patients more likely to benefit from a subsequent transplant.

Uptake of dimannoside clusters and oligomannosides by human dendritic cells.

Knowing that human blood monocyte-derived dendritic cells express cell-surface mannose-specific lectins, we prepared various mannoses containing glycoconjugates with the aim of developing highly specific synthetic carriers of oligonucleotides and genes. Conjugates were prepared from oligosaccharides obtained by hydrazinolysis of Saccharomyces cerevisiae invertase glycopeptides. The reducing saccharides were converted into glycosynthons, i.e., into glyco-amino acids. Fluorescein derivatives were obtained by coupling the free carboxyl group of oligosaccharyl-pyroglutamate to the alpha-amino group of epsilon-fluoresceinyl-thiocarbamyl lysine methyl ester. It has been shown by others that glycosylated linear oligolysines containing up to six alpha-D-mannopyranosylphenylthiocarbamyl units have a high affinity for the human mannose receptor. In order to obtain fully biodegradable clusters and to improve both the specificity and the selectivity, disaccharides transformed into glycosynthons were coupled to pentalysine carriers (Lys5-Ala-Cys-NH2). Glycosylated pentalysyl cysteine conjugates were made fluorescent upon substitution of the cysteine thiol group with fluorescein iodoacetamide. As shown by flow cytofluorimetry, both the dimannoside clusters and yeast oligomannosides were very efficiently taken up by DC, conversely lactoside clusters were not.

[Sorting CD34 antigens: objectives, biological and clinical results]. / Tri CD34: objectifs, résultats biologiques, résultats cliniques.

CD34 SORTING: CD34 sorting is a means of selecting hematopoietic stem cells among heterogeneous populations of cells. The technique is based on the fact that only hematopoietic stem cells (excepting a few tumoral cells) carry the CD34 antigen. Generally this type of manipulation is performed in case of stem cell grafts or for the treatment of certain malignant hematological diseases or certain solid tumors. OBJECTIVES: For autologous grafts, CD34 sorting reduces the number of tumoral cells contained in the graft and thus limits the risk of induced relapse. For allografts, CD34 sorting reduces the number of reinjected T cells, and thus the risk of severe, often life-threatening, graft-versus-host disease. TECHNIQUES AND BIOLOGICAL RESULTS: Five techniques have been developed using anti-CD34 antibodies. Currently, the most widely used techniques rely on immunomagnetic methods where the antibody is bound to a magnetic bead (Baxter, Miltenyi). The Systemix technique (high-flow cytometry) can only be applied in industrial settings. In all cases, there is at least a 2 log reduction in the number of tumoral cells and T cells with a more or less pronounced loss of CD34 cells (maximal loss 50%). CLINICAL RESULTS: No randomized study has been reported for CDR-sorted autografts in comparison with non-sorted grafts, but several authors have published results showing an advantage in terms of overall survival and disease-free survival. For allografts, only a few studies have been reported to date. CD34 sorting appears to lower the rate of graft-versus-host disease if sufficient T-cell depletion is achieved. OTHER ASPECTS: CD34 sorting is also used in other types of cell manipulations: cell expansion, gene transfer, production of dendritic cells for immunotherapy.

[Positive selection of hematopoietic CD 34 stem cells for autograft]. / Sélection positive de cellules souches hématopoïétiques CD 34 pour autogreffe.

The CD 34 antigen is a glycoprotein found on the surface of hematopoietic stem cells and early committed progenitors. The CE 34 stem cells from 14 samples of bone marrow, cord blood or leucapheresis were isolated using a positive selection procedure involving an anti CD 34 biotinylated monoclonal antibody and an avidin immunoabsorption device. Results showed that in 60 percent of samples, the positively-selected fractions contained more than 70 percent CD 34 cells. Concentration in CFU-GM and BFU-E progenitors increased 15 and 26 fold respectively in the CE 34 enriched samples. Long-term culture of two samples demonstrated that nearly all of the most immature progenitors were recovered in the procedure. These preliminary results showed that the positive selection technique of CD 34 hematopoietic stem cells is now available for use in autologous or allogeneic hematopoietic stem cell transplantation.

Met signaling regulates growth, repopulating potential and basal cell-fate commitment of mammary luminal progenitors: implications for basal-like breast cancer.

Basal-like breast cancer is an aggressive subtype of mammary carcinoma. Despite expressing basal markers, typical of mammary stem cells, this tumor has been proposed to originate from luminal progenitors, which are downstream of stem cells along the mammary epithelial hierarchy. This suggests that committed luminal progenitors may reacquire basal, stem-like characteristics, but the mechanisms that regulate this transition remain unclear. Using mouse models, we found that luminal progenitors express high levels of the Met receptor for hepatocyte growth factor (HGF), as compared with the other mammary epithelial sub-populations. Constitutive activation of Met led luminal progenitors to attain stem cell properties, including enhanced clonogenic activity in vitro and de novo ability to reconstitute mammary glands in repopulation assays in vivo. Moreover, in response to Met signaling, luminal progenitors gave rise to hyperplastic ductal morphogenesis and preferentially underwent basal lineage commitment at the expense of luminal cell-fate specification. Opposite and symmetric results were produced by systemic pharmacological inhibition of Met. Hence, Met signaling targets luminal progenitors for expansion, impairs their differentiation toward the mature luminal phenotype and enables their commitment toward the basal lineage. These results emphasize a critical role for Met in promoting deregulated proliferation and basal plasticity of normal luminal progenitors in the mammary gland, a complex of events that may be required for sustaining the functional and phenotypic properties of basal-like breast tumors.