Background aims Previous studies in xenograft models have shown that human peripheral blood progenitor cells (PBPC) mobilized with the CXCR4 antagonist plerixafor (AMD3100) have a higher bone marrow ...(BM) reconstitution potential than granulocyte–colony-stimulating factor (G-CSF)-mobilized PBPC. Methods PBPC obtained during G-CSF-supported mobilization before and after a supplementary administration of AMD3100 from patients with multiple myeloma and non-Hodgkin's lymphoma ( n = 15; phase II study) were investigated for co-expression of primitive and lineage-associated markers, their proliferative activity in vitro and repopulation potential after clinical transplantation. Results A significant increase in primitive CD34+ CD38− cells was observed in intraindividual comparisons of all patients after administration of G-CSF+AMD3100 (peripheral blood: median 8-fold, range 2,4-fold - 39-fold) compared with G-CSF alone. Using a long-term culture-initiating cell assay, this increase was confirmed. After transplantation of G-CSF+AMD3100-mobilized PBPC, the time to leukocyte reconstitution >1 × 103 /μL and platelet reconstitution >2 × 104 /μL was 14 (10–19 days) and 13 days (10–15 days), respectively. A complete and stable hematologic reconstitution (platelets >1.5 × 105 /μL) was observed in 91% of all patients within 35 days. Conclusions An additional application of AMD3100 to a standard G-CSF mobilization regimen leads to a significant increase in primitive PBPC with high repopulation capacity.
Despite Imatinib's remarkable success in chronic myelogenous leukemia treatment, monotherapy frequently causes resistance, underlining the rationale for combination chemotherapy. A potential approach ...would be interrupting the SDF-1/CXCR4 axis using the selective CXCR4 antagonist Plerixafor (previously AMD3100), as this axis has been reported to provide survival-enhancing effects to myeloid progenitor cells. By efficient CXCR4 blocking in the CXCR4+/BCR-ABL+ cell line BV-173, plerixafor (1-100 μM) significantly inhibits SDF-1α-mediated chemotaxis and cell migration toward the murine stroma cell line FBMD-1. Furthermore, plerixafor also significantly (10-100 μM) increased the detachment rate of SDF-1-mediated/VCAM-1-associated cell adherence under shear stress. Using a stroma-dependent coculture assay, plerixafor sensitized BCR-ABL+ cells toward tyrosine kinase inhibitor therapy. Because the level of cell killing nearly reached that of samples cultured without stroma, a cell-cell interaction disruption seems to improve the efficacy of BCR-ABL-targeting drugs. In addition, we could show that exposure of BCR-ABL+ cells to Imatinib or Nilotinib induced an increase in surface CXCR4 expression. Our data suggest that for BCR-ABL+ leukemia, the selective blocking of the SDF-1/CXCR4 axis by plerixafor is a potential mechanism to overcome the protective effect of the bone marrow environment, thereby increasing the therapeutic potency of anti-BCR-ABL drugs and the therapeutic window.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Autologous and allogeneic hematopoietic stem cell (HSC) transplantation are considered the standard of care for many malignancies including lymphoma, multiple myeloma, and some leukemias. In many ...cases, mobilized peripheral blood has become the preferred source for HSCs. Plerixafor, an inhibitor of the interaction between CX chemokine receptor 4 (CXCR4) and stromal derived factor-1 alpha (SDF-1), has been evaluated in clinical trials and approved by the FDA and EMA. This agent has very modest toxicity and appears to be quite potent at HSC mobilization. Current clinical indications for the use of plerixafor are the subject of this review.
Reports on insertional "genotoxicity" in patients have created intense interest in characterizing retroviral vector integrations on the genomic level. The retroviral vector SF91m3 was used for ...transduction of human peripheral blood progenitor cells (PBPC). These PBPC were transplanted into nonobese diabetic/severe combined immunodeficient mice. A total of 186 retroviral vector integration sites were isolated by ligation-mediated PCR from chimeric mouse bone marrow of five PBPC donors, sequenced, and blasted against the human genome. Preferred integration near the transcription start regions, within CpG islands, and within Alu regions was observed. Detailed analysis of targeted RefSeq genes showed a favored integration within the first intron. Integrations were most common in genes coding for signaling proteins, transcription factors, and kinases. In all genes targeted independently multiple times the respective orientation of the provirus within the gene was identical, indicating integration hot spot regions and similar steric determinants for integration sites. Possible explanations for these findings could be nonrandom vector integration, clonal selection due to gene expression interference, or engraftment issues related to gene insertion in signaling and cell cycle genes. The low frequency of integrations in exons may be reassuring as to the safety of retroviral gene therapy with normal human PBPC.
The randomized PANAMA trial investigated the efficacy of panitumumab (Pmab) when added to maintenance therapy with fluorouracil and folinic acid (FU/FA) in patients with
wild-type metastatic ...colorectal cancer.
Following first-line induction therapy with six cycles of FU/FA and oxaliplatin plus Pmab, responding patients (stable disease or partial or complete remission) were randomly assigned (1:1, open-label) to maintenance treatment with either FU/FA plus Pmab or FU/FA alone. The primary objective was to demonstrate superiority of progression-free survival (PFS, time from random assignment until progression or death) in favor of FU/FA plus Pmab with a hazard ratio (HR) of 0.75, a power of 80%, and a significance level of 10%. Secondary end points included overall survival, objective response rate of maintenance therapy, and toxicity. Survival end points were analyzed by the Kaplan-Meier method and compared by log-rank test and Cox regressions. Dichotomous variables were compared by Fisher's exact test; odds ratios were indicated when appropriate. The trial is registered with ClinicalTrials.gov (NCT01991873).
Overall, 248 patients were randomly assigned and received maintenance therapy with either FU/FA plus Pmab (125 patients) or FU/FA alone (123 patients). At data cutoff, with 218 events (of 218 needed), PFS of maintenance therapy was significantly improved with FU/FA plus Pmab (8.8 months
5.7 months; HR, 0.72; 80% CI, 0.60 to 0.85;
= .014). Overall survival (event rate 54%) numerically favored the FU/FA plus Pmab arm (28.7 months
25.7 months; HR, 0.84; 95% CI, 0.60 to 1.18;
= .32). Objective response rates were 40.8% in patients receiving FU/FA plus Pmab versus 26.0% in patients receiving FU/FA alone (odds ratio, 1.96; 95% CI, 1.14 to 3.36;
= .02). The most frequent Common Terminology Criteria for Adverse Event grade ≥ 3 event during maintenance therapy was skin rash (7.2%).
In
wild-type metastatic colorectal cancer, maintenance therapy with FU/FA plus Pmab induced a significantly superior PFS compared with FU/FA alone. If active maintenance therapy is aspired following induction therapy with FU/FA and oxaliplatin plus Pmab, FU/FA plus Pmab appears to be the most favorable option.
Objective Currently standard recombinant adeno-associated virus serotype 2(rAAV2)–based vectors lack the efficiency for gene transfer into primary human CD34+ peripheral blood progenitor cells ...(PBPC). Materials and Methods An advancement in vector development now allows the generation of rAAV capsid mutants that offer higher target cell efficiency and specificity. To increase the gene transfer into hematopoietic progenitor cells, we applied this method for the first time on primary human CD34+ PBPC cells. Results On a panel of leukemia cell lines (CML/AML), significantly higher gene transfer efficiency of the rAAV capsid mutants (up to 100% gene transfer) was observed compared to standard rAAV2 vectors. A higher transduction efficiency in the imatinib-resistant cell line LAMA84-R than in their sensitive counterpart LAMA84-S and a pronounced difference in susceptibility for the capsid mutants vs rAAV2 in LAMA84-S were particularly striking. On solid tumor cell lines, on the other hand, rAAV2 was more efficient than the capsid mutants, suggesting an increased specificity of our capsid mutants for hematopoietic progenitor cells. On primary human CD34+ PBPC significantly higher (up to eightfold; 16% green fluorescent protein–positive) gene transfer could be obtained with the newly generated vectors compared to standard rAAV2 vectors. Conclusion These novel vectors may enable efficient gene transfer using rAAV-based vectors into primary human blood progenitor cells for a future clinical application.
Background: Resistance to imatinib monotherapy frequently emerges in advanced stages of chronic myelogenous leukemia (CML),
supporting the rationale for combination drug therapy. In the present ...study, the activities of the farnesyltransferase inhibitors
(FTIs) L744,832 and LB42918, as single agents and in combination with imatinib, were investigated in different imatinib-sensitive
and -resistant BCR-ABL-positive CML cells. Materials and Methods: Growth inhibition of the cell lines and primary patient
cells was assessed by MTT assays and colony-forming cell assays, respectively. Drug interactions were analyzed according to
the median-effect method of Chou and Talalay. The determination of apoptotic cell death was performed by annexin V/propidium
iodide staining. Results: Combinations of both FTIs with imatinib displayed synergism or sensitization (potentiation) in all
the cell lines tested. In primary chronic phase CML cells, additive and synergistic effects were discernible for the combination
of imatinib plus L744,832 and imatinib plus LB42918, respectively. Annexin V/propidium iodide staining showed enhancement
of imatinib-induced apoptosis with either drug combination, both in imatinib-sensitive and -resistant cells. Conclusion: The
results indicated the potential of L744,832 and LB42918 as combination agents for CML patients on imatinib treatment.
3506 Background: The randomized open-label phase II PanaMa trial compared FU/FA with or without pmab maintenance after mFOLFOX6+pmab induction for RAS wild-type mCRC. Updated efficacy results of the ...Full Analysis Set are presented. Methods: Median progression-free survival (PFS), overall survival (OS), PFS of re-induction (PFS re-ind.), time to failure of strategy (TFS), and objective response rates (ORR) were compared by log-rank test / Cox regression and Fisher’s exact test. Results: PFS was significantly (8.8 vs. 5.8 months, HR=0.73 (95%CI 0.56 – 0.94), P=0.015) and OS numerically longer (29.9 vs. 24.7 months, HR=0.85 (95%CI 0.64 – 1.12), P=0.24). PFS re-ind. was significantly shorter after pmab maintenance (4.1 vs. 7.4 months, HR=1.93 (95%CI 1.33 – 2.82), P<0.001). TFS was comparable (17.1 vs. 15.7 months, HR=0.98 (95%CI 0.68 – 1.42), P=0.92). Molecular subgroups are displayed in Table 1. ORR of FU/FA+pmab was comparable to FU/FA during induction (74.4% vs. 76.4%, P=0.77), higher during maintenance (40.8% vs. 29.3%, P=0.06), but lower at re-induction (8.0% vs. 35.9%, P<0.001). Conclusions: PFS remained improved by the addition of pmab to FU/FA maintenance therapy, while OS was not significantly longer. Re-induction of pmab+mFOLFOX6 did not provide benefit following pmab maintenance regarding PFS. Clinical trial information: NCT01991873 . Table: see text
3528 Background: mRNA expression of amphiregulin ( AREG) and epiregulin ( EREG) as ligands of the epidermal growth factor receptor (EGFR) were associated with response to anti-EGFR directed ...antibodies in metastatic colorectal cancer (mCRC). Their role for maintenance treatment remained unclear yet and was investigated in the PanaMa trial (panitumumab (Pmab) and fluorouracil/folinic acid (FU/FA) vs. FU/FA alone after Pmab+FOLFOX induction therapy in RAS wild-type mCRC). Methods: Gene expression was measured after mRNA isolation in 196 of 248 patients of the full analysis set. The analysis was conducted using a customized Nanostring PanCancer Progression Panel. AREG and EREG mRNA expression was dichotomized by median. High combined expression was defined as mRNA expression of AREG and EREGequal or above the median. Median progression-free (PFS) and overall survival (OS) since start of maintenance were estimated by Kaplan-Meier-method and Cox-regression, using the log rank test. Objective response rates (ORR) of maintenance therapy were compared by Fisher’s exact test. Treatment interaction was tested by Cox regression. Results: In 196 patients with available mRNA expression data, high AREG, EREG and combined AREG / EREG expression were observed in 103 (52.6%), 97 (49.5%) and 84 (42.9%), respectively. Regardless of treatment, high combined AREG / EREG expression was associated with prolonged PFS (7.7 vs. 5.8 months, HR 0.69 (95% CI 0.51 – 0.93), P=0.016), OS (30.1 vs. 24.4 months, HR 0.58 (95% CI 0.41 – 0.82), P=0.002) and increased ORR of maintenance treatment (39.3% vs. 28.6%, P=0.13), compared to low expression. Tumors with high combined AREG / EREG expression were associated with numerical longer PFS, OS and higher ORR when treated with Pmab+FU/FA maintenance (Table). Significant interaction of combined AREG / EREG expression with treatment was observed in terms of PFS ( P=0.003) and OS ( P=0.016). Conclusions: Combined AREG and EREG mRNA expression was confirmed as prognostic biomarker for mCRC patients receiving maintenance treatment. Efficacy of maintenance treatment might potentially be higher for Pmab+FUFA maintenance in mCRC with high combined AREG / EREG expression in the PanaMa trial. Table: see text
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