A. Morabito

The engagement of CTLA-4 on primary melanoma cell lines induces antibody-dependent cellular cytotoxicity and TNF-α production.

BackgroundCTLA-4 (Cytotoxic T lymphocyte antigen-4) is traditionally known as a negative regulator of T cell activation. The blocking of CTLA-4 using human monoclonal antibodies, such as Ipilimumab, is currently used to relieve CTLA-4-mediated inhibition of anti-tumor immune response in metastatic melanoma. Herein, we have analyzed CTLA-4 expression and Ipilimumab reactivity on melanoma cell lines and tumor tissues from cutaneous melanoma patients. Then, we investigated whether Ipilimumab can trigger innate immunity in terms of antibody dependent cellular cytotoxicity (ADCC) or Tumor Necrosis Factor (TNF)-α release. Finally, a xenograft murine model was set up to determine in vivo the effects of Ipilimumab and NK cells on melanoma.MethodsCTLA-4 expression and Ipilimumab reactivity were analyzed on 17 melanoma cell lines (14 primary and 3 long-term cell lines) by cytofluorimetry and on 33 melanoma tissues by immunohistochemistry. CTLA-4 transcripts were analyzed by quantitative RT-PCR. Soluble CTLA-4 and TNF-α were tested by ELISA. Peripheral blood mononuclear cells (PBMC), NK and γδT cells were tested in ADCC assay with Ipilimumab and melanoma cell lines. TNF-α release was analyzed in NK-melanoma cell co-cultures in the presence of ipilimumab. In vivo experiments of xenotransplantation were carried out in NOD/SCID mice. Results were analyzed using unpaired Student’s t-test.ResultsAll melanoma cell lines expressed mRNA and cytoplasmic CTLA-4 but surface reactivity with Ipilimumab was quite heterogeneous. Accordingly, about 2/3 of melanoma specimens expressed CTLA-4 at different level of intensity.Ipilimumab triggered, via FcγReceptorIIIA (CD16), ex vivo NK cells as well as PBMC, IL-2 activated NK and γδT cells to ADCC of CTLA-4+ melanoma cells. No ADCC was detected upon interaction with CTLA-4- FO-1 melanoma cell line. TNF-α was released upon interaction of NK cells with CTLA-4+ melanoma cell lines. Remarkably, Ipilimumab neither affected proliferation and viability nor triggered ADCC of CTLA-4+ T lymphocytes. In a chimeric murine xenograft model, the co-engraftment of Ipilimumab-treated melanoma cells with human allogeneic NK cells delayed and significantly reduced tumor growth, as compared to mice receiving control xenografts.ConclusionsOur studies demonstrate that Ipilimumab triggers effector lymphocytes to cytotoxicity and TNF-α release. These findings suggest that Ipilimumab, besides blocking CTLA-4, can directly activate the elimination of CTLA-4+ melanomas.

Association of −318 C/T and +49 A/G cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms with a clinical subset of Italian patients with systemic sclerosis

Systemic sclerosis (SSc) is a complex and heterogeneous autoimmune disorder with a multi‐factorial pathogenesis. Like other autoimmune disorders, the possible role of specific cytotoxic T lymphocyte antigen‐4 (CTLA‐4) gene polymorphisms in predisposing to SSc has been hypothesized, but it remains controversial. CTLA‐4 promoter (−318C/T) and exon 1 (+49 A/G) polymorphisms have been analysed in 43 Italian females with SSc and in 93 unrelated matched healthy controls by a newly designed tetra‐primer amplification refractory mutation system–polymerase chain reaction (T‐ARMS–PCR) method. No significant association has been found with either polymorphisms.Nevertheless, SSc patients without concomitant Hashimotos thyroiditis (HT) were carrying both the −318T allele (P = 0·031) and the +49 G allele (P = 0·076) more frequently than SSc patients with HT [defined by positivity for anti‐thyroperoxidase (TPO) and anti‐thyroglobulin (TGA) autoantibodies] than controls. Haplotype analysis confirms this association (P = 0·028), and suggests the predominant role of the −318T, whereas that of the +49 G, if any, seems weak. Thus, in Italian SSc patients the CTLA‐4 −318C/T promoter polymorphism appears to be associated with the susceptibility to develop SSc without thyroid involvement. Larger studies are needed to confirm these findings and to clarify whether the −318C/T polymorphism is the functional responsible or whether it reflects the presence of another linked genetic element in the same chromosomal region.

CTLA-4 is expressed by human monocyte— derived dendritic cells and regulates their functions

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is the major negative regulator of T-cell responses, although growing evidence supports its wider role as an immune attenuator that may also act in other cell lineages. Here, we have analyzed the expression of CTLA-4 in human monocytes and monocyte-derived dendritic cells (DCs), and the effect of its engagement on cytokine production and T-cell stimulatory activity by mature DCs. CTLA-4 was highly expressed on freshly isolated monocytes, then down-modulated upon differentiation toward immature DCs (iDCs) and it was markedly upregulated on mature DCs obtained with different stimulations (lipopolysaccharides [LPS], Poly:IC, cytokines). In line with the functional role of CTLA-4 in T cells, treatment of mDCs with an agonistic anti-CTLA-4 mAb significantly enhanced secretion of regulatory interleukin (IL)-10 but reduced secretion of IL-8/IL-12 pro-inflammatory cytokines, as well as autologous CD4+ T-cell proliferation in response to stimulation with recall antigen purified protein derivative (PPD) loaded-DCs. Neutralization of IL-10 with an anti-IL-10 antibody during the mDCs-CD4+ T-cell co-culture partially restored the ability of anti-CTLA-4-treated mDCs to stimulate T-cell proliferation in response to PPD. Taken together, our data provide the first evidence that CTLA-4 receptor is expressed by human monocyte-derived mDCs upon their full activation and that it exerts immune modulatory effects.

Is epirubicin effective in first-line chemotherapy of metastatic breast cancer (MBC) after an epirubicin-containing adjuvant treatment? A single centre phase III trial.

The aim of the study was to demonstrate the superiority of docetaxel and epirubicin vs docetaxel alone as first-line therapy in metastatic breast cancer patients pretreated with adjuvant or neoadjuvant epirubicin. We compared single agent docetaxel 100 mg m−2 (D) with the combination of docetaxel 80 mg m−2 and epirubicin 75 mg m−2 (ED). The response rate (72 vs 79%), the progression-free survival (median 9 vs 11 months) and the overall survival (median 18 vs 21 months) were not significantly different between the ED (n=26) and D arms (n=25), respectively. Leucopaenia, nausea and stomatitis were significantly worse with ED. In conclusion, epirubicin should not be administered in combination with taxanes in metastatic breast cancer patients relapsed after an anthracycline-based adjuvant or neoadjuvant therapy.

CTLA-4 expressed by chemoresistant, as well as untreated, myeloid leukaemia cells can be targeted with ligands to induce apoptosis

We have previously reported that about 80% of acute myeloid leukaemia (AML) samples tested at diagnosis constitutively expressed cytotoxic T‐lymphocyte‐associated antigen‐4 (CTLA‐4). The present study compared CTLA‐4 expression and function of leukaemic cells from AML patients at diagnosis with those from AML patients resistant to conventional chemotherapy. We also explored the possibility of targeting CTLA‐4 for apoptosis induction in chemoresistant AML cells. AML cells either from untreated patients (n = 15) or in chemoresistant phase (n = 10) were analysed for CTLA‐4 protein and transcript expression by flow cytometry and reverse transcription‐polymerase chain reaction respectively. CTLA‐4 expression was similar in untreated and in chemoresistant samples and was not associated with patients’ clinical features. In chemoresistant AML cells, CTLA‐4 transduced an apoptotic signal on engagement with its recombinant ligands r‐CD80 and r‐CD86, which induced an average of 71% and 62% apoptotic cells, respectively, at highest concentration. Apoptosis was equally induced in untreated leukaemic cells accompanied by cleavage of procaspase‐8 and ‐3. Thus, this study provides the first evidence that killing of leukaemic cells from AML patients may be obtained by the engagement of CTLA‐4 with its ligands, opening the way to a novel potential therapeutic approach based on triggering the CTLA‐4 molecule to circumvent chemoresistance in AML.

CTLA-4 +49A>G polymorphism of recipients of HLA-matched sibling allogeneic stem cell transplantation is associated with survival and relapse incidence

Conflicting observations have been reported about the role of CTLA-4 gene polymorphisms in the clinical outcome of allogeneic hematopoietic stem cell transplantation (HSCT). We have investigated three polymorphisms of the CTLA-4 gene (−318C>T, +49A>G, CT60G>A) in 133 donor/recipient pairs who underwent HLA-matched sibling donor HSCT for hematological malignancies. We found no association of the clinical outcome of the HSCT with either recipient or donor −318C>T and CT60G>A polymorphisms. At variance, we found a significant association of donor +49A>G G/G genotype with longer overall survival (OS; log-rank test, P = 0.04), and the number of +49A>G G-alleles in the recipient with longer OS (P = 0.027), longer disease-free survival (P = 0.036) and reduced relapse rate (P = 0.042). However, only recipient +49A>G polymorphism was retained as independent prognostic factor in a multivariate analysis, suggesting that the expression of CTLA-4 on the cells of recipient may be relevant for the clinical outcome of HSCT.

Bevacizumab in non small cell lung cancer: development, current status and issues.

Bevacizumab is a monoclonal antibody directed against Vascular Endothelial Growth Factor (VEGF). Evidence about its efficacy in addition to first-line chemotherapy in non-small-cell-lung-cancer (NSCLC) has been produced by two large randomized phase III clinical trials (ECOG 4599 and AVAiL), conducted in a clinically selected population with non-squamous histology and without major risk factors for bleeding. In the ECOG 4599 trial, the addition of bevacizumab (15 mg/kg) to carboplatin plus paclitaxel produced a statistically significant and clinically relevant improvement in overall survival (OS), that was the primary endpoint of the trial (12.3 months vs 10.3 months, HR 0.79; p=0.003). Furthermore, patients receiving bevacizumab showed a significant improvement in progression-free survival (PFS) and in objective response rates. Treatment with bevacizumab was well tolerated by the majority of patients, but was still associated with increased risk of clinically significant bleeding (4.4% vs 0.7%, p0.001). In the AVAiL trial the addition of bevacizumab (at the dose of 7.5 and 15 mg/kg) to cisplatin plus gemcitabine produced a small improvement in PFS, but no differences in OS. Information from retrospective analysis and two large observational studies (SAIL and ARIES) have confirmed the safety profile of first-line bevacizumab with a wide range of chemotherapy partners, but whether its efficacy is comparable when combined with the different regimens is still unknown. The identification of predictive factors of efficacy would be relevant for the optimal use of the drug, but to date we have no conclusive data in this direction.

Bone effect of adjuvant tamoxifen, letrozole or letrozole plus zoledronic acid in early-stage breast cancer: the randomized phase 3 HOBOE study

BACKGROUND To measure bone mineral density (BMD) reduction produced by letrozole as compared with tamoxifen and the benefit of the addition of zoledronic acid. PATIENTS AND METHODS A phase 3 trial comparing tamoxifen, letrozole or letrozole+zoledronic acid in patients with hormone receptor-positive early breast cancer was conducted; triptorelin was given to premenopausal patients. Two comparisons were planned: letrozole versus tamoxifen and letrozole+zoledronic acid versus letrozole. Primary end point was the difference in 1-year change of T-score at lumbar spine (LTS) measured by dual energy X-ray absorptiometry scan. RESULTS Out of 483 patients enrolled, 459 were available for primary analyses. Median age was 50 (range 28-80). The estimated mean difference (95% confidence interval [CI]) in 1-year change of LTS was equal to -0.30 (95% CI -0.44 to -0.17) in the letrozole versus tamoxifen comparison (P<0.0001) and to +0.60 (95% CI +0.46 to +0.77) in the letrozole+zoledronic acid versus letrozole comparison (P<0.0001). Bone damage by letrozole decreased with increasing baseline body mass index in premenopausal, but not postmenopausal, patients (interaction test P=0.004 and 0.47, respectively). CONCLUSIONS In the HOBOE (HOrmonal BOne Effects) trial, the positive effect of zoledronic acid on BMD largely counteracts damage produced by letrozole as compared with tamoxifen. Letrozole effect is lower among overweight/obese premenopausal patients.

MicroRNA in Glioblastoma: An Overview

Glioblastoma is the most aggressive brain tumor and, even with the current multimodal therapy, is an invariably lethal cancer with a life expectancy that depends on the tumor subtype but, even in the most favorable cases, rarely exceeds 2 years. Epigenetic factors play an important role in gliomagenesis, are strong predictors of outcome, and are important determinants for the resistance to radio- and chemotherapy. The latest addition to the epigenetic machinery is the noncoding RNA (ncRNA), that is, RNA molecules that are not translated into a protein and that exert their function by base pairing with other nucleic acids in a reversible and nonmutational mode. MicroRNAs (miRNA) are a class of ncRNA of about 22 bp that regulate gene expression by binding to complementary sequences in the mRNA and silence its translation into proteins. MicroRNAs reversibly regulate transcription through nonmutational mechanisms; accordingly, they can be considered as epigenetic effectors. In this review, we will discuss the role of miRNA in glioma focusing on their role in drug resistance and on their potential applications in the therapy of this tumor.

Association of CTLA-4 gene variants with response to therapy and long-term survival in metastatic melanoma patients treated with ipilimumab: An Italian melanoma intergroup study

Ipilimumab (IPI) blocks CTLA-4 immune checkpoint resulting in T cell activation and enhanced antitumor immunity. IPI improves overall survival (OS) in 22% of patients with metastatic melanoma (MM). We investigated the association of CTLA-4 single nucleotide variants (SNVs) with best overall response (BOR) to IPI and OS in a cohort of 173 MM patients. Patients were genotyped for six CTLA-4 SNVs (−1661A>G, −1577G>A, −658C>T, −319C>T, +49A>G, and CT60G>A). We assessed the association between SNVs and BOR through multinomial logistic regression (MLR) and the prognostic effect of SNVs on OS through Kaplan–Meier method. Both −1577G>A and CT60G>A SNVs were found significantly associated with BOR. In particular, the proportion of responders was higher in G/G genotype while that of stable patients was higher in A/A genotype. The frequency of patients experiencing progression was similar in all genotypes. MLR evidenced a strong downward trend in the probability of responsiveness/progression, in comparison to disease stability, as a function of the allele A “dose” (0, 1, or 2) in both SNVs with reductions of about 70% (G/A vs G/G) and about 95% (A/A vs G/G). Moreover, −1577G/G and CT60G/G genotypes were associated with long-term OS, the surviving patients being at 3 years 29.8 and 30.8%, respectively, as compared to 12.9 and 14.4% of surviving patients carrying −1577G/A and CT60G/A, respectively. MM patients carrying −1577G/G or CT60G/G genotypes may benefit from IPI treatment in terms of BOR and long-term OS. These CTLA-4 SNVs may serve as potential biomarkers predictive of favorable outcome in this subset of patients.