Nadia Gibelli

Pilot Study of the Mechanism of Action of Preoperative Trastuzumab in Patients with Primary Operable Breast Tumors Overexpressing HER2

Purpose: To elucidate the mechanism by which trastuzumab, a humanized monoclonal antibody against HER2 with proven survival benefit in women with HER2-positive metastatic breast cancer, mediates its antitumor activity. Experimental Design: A pilot study including 11 patients with HER2-positive tumors treated in a neo-adjuvant setting with trastuzumab was performed. Trastuzumab was administered i.v. at a dose of 4 mg/kg followed by three weekly i.v. doses of 2 mg/kg. The primary tumor was surgically removed 7 days after the last treatment. Surgical samples, tumor biopsies, and lymphocytes from these patients were collected for biological studies. Result: Clinical data indicated one complete pathological remission and four partial remissions using RECIST (Response Evaluation Criteria in Solid Tumors). Trastuzumab was well tolerated and neither serious adverse events nor changes in cardiac function were observed during this short-term treatment and after surgery. The biological data showed that, independent of response, (a) all patients showed high levels of circulating trastuzumab; (b) saturating level of trastuzumab was present in all of the tumors; (c) no down-modulation of HER2 was observed in any tumors; (d) no changes in vessel diameter was observed in any tumors; (e) no changes in proliferation was observed in any tumors; and (f) a strong infiltration by lymphoid cells was observed in all cases. Patients with complete remission or partial remission were found to have a higher in situ infiltration of leukocytes and a higher capability to mediate in vitro antibody-dependent cellular cytotoxicity activity. Conclusions: The results of this pilot study argue against trastuzumab activity in patients through down-modulation of HER2 but in favor of antibody-dependent cellular cytotoxicity guiding efforts to optimize the use of trastuzumab in breast cancer patients.

Elements Related to Heterogeneity of Antibody-Dependent Cell Cytotoxicity in Patients Under Trastuzumab Therapy for Primary Operable Breast Cancer Overexpressing Her2

Preliminary results from a pilot trial on trastuzumabs mechanism of action against operable breast tumors overexpressing Her2 suggested a role for antibody-dependent cell cytotoxicity (ADCC). To examine factors affecting ADCC intensity and variability, we extended this study to the phenotypic and functional analysis of circulating mononuclear cells in 18 patients. ADCC was induced by trastuzumab therapy in 15 of 18 patients (83%). Inability to develop ADCC in three patients did not depend on inadequate levels of trastuzumab because further increase in its concentration in vitro was ineffective. Rather, susceptibility to develop ADCC was fairly predicted by test with trastuzumab before therapy and was correlated to the number of lymphocytes coexpressing CD16 and CD56. Phenotypic analysis at the end of ADCC evaluating down-regulation of CD16, and up-regulation of CD69 and CD107a, confirmed that natural killer (NK) cells and CD56(+) T cells were involved in productive engagement of trastuzumab. Also, the killing efficiency of CD16(+) lymphocytes was influenced by 158 V/F polymorphism of Fc gamma RIII (CD16), whereas variations of CD247 on NK cells were consistent with trends between ADCC before and after therapy. Complete pathologic response was observed in one patient showing ADCC of outstanding intensity, whereas four cases of partial response showed intermediate ADCC; none of the three patients unable to mount ADCC had significant tumor regression. These data indicate that quantity and lytic efficiency of CD16(+) lymphocytes are major factors for ADCC induction by trastuzumab, and confirm that breast cancer responses to short-term trastuzumab monotherapy may depend on involvement of the ADCC mechanism.

Mitomycin C as an alternative to irradiation to inhibit the feeder layer growth in long-term culture assays

BACKGROUND Mitomycin C (MMC), an antitumoral antibiotic, has been described inhibiting the proliferation of different cell types in vitro. Since irradiation is commonly used to stop the cell growth of adherent cells in several experimental models, we aimed to define the optimal dose and incubation time of MMC capable of inhibiting the growth of murine fibroblasts, used as an adherent feeder layer in long-term hematopoietic culture assay. METHODS M2 10B4 (both parental and engineered to produce human IL-3 and G-CSF) and Sl/Sl (engineered to produce human IL-3 and steel factor) murine fibroblast cell-lines, frequently used in LTC-IC assay, were incubated with increasing doses of MMC for either a short (3 h) or a long (16 h) period. The efficiency of MMC in stopping the cell growth was evaluated for 5 days following MMC removal. The effects of MMC treatment on human hematopoietic cells were studied using both LTC-IC and limiting dilution (CAFC) assays. RESULTS The growth of M2 10B4 cells was stopped at 3 and 16 h in the presence of 20 microg/mL and 2 microg/mL of MMC, respectively while Sl/Sl fibroblasts required a lower dose of drug (2 and 0.2 microg/mL, respectively). No significant difference was found between the number of LTC-IC or CAFC obtained from cultures containing irradiated or MMC-treated feeder cells. DISCUSSION MMC inhibits the growth of murine fibroblasts used as adherent feeder cells in long-term culture assays, without interfering with the subsequent growth of co-cultured hemopoietic cells. Different cell types might present a different sensitivity to MMC and therefore a dose-response curve to MMC has to be obtained for each cell type of interest.

Epithelial tumour cell detection and the unsolved problems of nested RT-PCR: a new sensitive one step method without false positive results

Sensitive detection of circulating epithelial cancer cells might have important therapeutic and prognostic implications in patients with breast cancer (BC) receiving high-dose chemotherapy and PBSC support. We have compared the specificity and sensitivity of the recently developed ‘one tube’ reverse transcriptase PCR (RT-PCR) assay with the more widely used nested RT-PCR method for detection of cytokeratin 19 (CK19)-positive cells. The analysis of 30 control samples provides evidence that one tube RT-PCR is highly specific in contrast to the nested method which showed 23% false positive results. The sensitivity of both techniques to detect tumour contamination was 10−6. PBSC harvests from 45 BC patients were tested with both RT-PCR methods and the results were compared with immunocytochemistry (ICC). The five samples found positive by ICC were also positive by one tube RT-PCR; in addition, 11 more samples were positive by one tube RT-PCR analysis. The greater number of PBSC found positive by one tube RT-PCR might be due to the larger number of cells analysed. We conclude that one tube RT-PCR is sensitive and reveals no false positive results. This method is less time consuming than the nested one, technically simpler and should be considered for tumour cell detection.

T-cell dynamics after high-dose chemotherapy in adults: elucidation of the elusive CD8+ subset reveals multiple homeostatic T-cell compartments with distinct implications for immune competence.

Recovery of total T cell numbers after in vivo T‐cell depletion in humans is accompanied by complex perturbation within the CD8+ subset. We aimed to elucidate the reconstitution of CD8+ T cells by separate analysis of putative naïve CD95− CD28+, memory CD95+ CD28+ and CD28− T cell compartments after acute maximal depletion by high‐dose chemotherapy (HD‐ChT) in women with high‐risk breast cancer. We found that recovery of putative naïve CD8+ CD95− CD28+ and CD4+ CD95− CD28+ T cells, was compatible with a thymus‐dependent regenerative pathway since their recovery was slow and time‐dependent, their values were tightly related to each other, and their reconstitution patterns were inversely related to age. By analysing non‐naïve T cells, a striking diversion between putative memory T cells and CD28− T cells was found. These latter increased early well beyond normal values, thus playing a pivotal role in total T‐cell homeostasis, and contributed to reduce the CD4 : CD8 ratio. In contrast, putative memory T cells returned to values not significantly different from those seen in patients at diagnosis, indicating that this compartment may recover after HD‐ChT. At 3–5 years after treatment, naïve T cells persisted at low levels, with expansion of CD28− T cells, suggesting that such alterations may extend further. These findings indicate that CD28− T cells were responsible for ‘blind’ T‐cell homeostasis, but support the notion that memory and naïve T cells are regulated separately. Given their distinct dynamics, quantitative evaluation of T‐cell pools in patients undergoing chemotherapy should take into account separate analysis of naïve, memory and CD28− T cells.

Ex vivo generation and expansion of anti-tumor cytotoxic T-cell lines derived from patients or their HLA-identical sibling

Successful ex‐vivo priming and long‐term maintenance of anti‐tumor cytotoxic T‐cell (CTL) lines are preliminary conditions for their use in approaches of adoptive immunotherapy for patients with cancer. We describe the results of a novel procedure for generating in vitro anti‐tumor CTL using CD8‐enriched peripheral blood mononuclear cells (PBMC) and dendritic cells (DC), pulsed with irradiated tumor cells (TC) as source of tumor antigen. Eight patients were enrolled in our study: 4 sarcoma, 2 renal cell carcinoma, 1 ovarian carcinoma and 1 breast carcinoma. Ten anti‐tumor CTL‐lines cytotoxic towards patient TC were generated. Five CTL‐lines were obtained using both DC and PBMC from the patients (autologous setting). For 5 CTL‐lines, DC derived from an HLA‐identical sibling were employed (allogeneic setting): patients or siblings PBMC were used to generate CTL‐lines in 2 and 3 cases, respectively,. After tumor‐specific rounds of stimulation, followed by antigen‐independent cycle of expansion, CTL‐lines obtained in both autologous and allogeneic setting showed an expansion of the absolute number of cultured cells. In 6 of 10 CTL‐lines, the majority of effector cells (>70%) were CD3+/CD8+, while in the remaining 4, 40–70% of effector cells were CD3+/CD4+. Both CD8+ and CD4+ T cells displayed anti‐tumor cytotoxic activity. Spectratyping analysis of the TCR‐Vβ subfamilies revealed a preferential expansion of oligoclonal populations in 18 of 24Vβ subfamily. Altogether these results demonstrate that our experimental approach is suitable for efficiently generating and expanding anti‐solid tumor CTL to be used for adoptive immunotherapy.

A new 'two step' procedure for 4.5 log depletion of T and B cells in allogeneic transplantation and of neoplastic cells in autologous transplantation

To evaluate a new ‘two step’ method for purging T, B and neoplastic cells from hematopoietic progenitor cells (PC), PCs were collected by apheresis and some suspensions were deliberately contaminated with 2–5% breast cancer cells. PCs were first processed through CellPro columns for positive selection of cells that express CD34. After this first step, the mean CD34+ cell recovery was 68 ± 12%, and CD34+ cell purity was 61 ± 11%; CD3+ and neoplastic cell depletion were 2.1 ± 0.4 and 1.9 ± 0.4 logs, respectively. Cells were further processed through the StemSep device for direct depletion of T and B cells or of breast cancer cells. After the first and the second step, overall CD34+ cell recovery was 50 ± 7%, T and B cell removal was 4.7 ± 0.4 log and neoplastic cell purging was 4.4 ± 0.3 log, ie significantly superior to methods described in the past.

Circulating CD33+ large mononuclear cells contain three distinct populations with phenotype of putative antigen‐presenting cells including myeloid dendritic cells and CD14+ monocytes with their CD16+ subset

BACKGROUND In peripheral blood, myeloid markers identify a heterogeneous mixture of cells in transit from the bone marrow to peripheral tissues. Similarly, HLA-class II DR expression usually identifies mononuclear cells with the potential for developing antigen-presenting activity. We gathered putative antigen presenting cells bearing myeloid markers (My-APC) to study their composition by cell surface phenotype. METHODS To gather and dissect My-APC phenotype while excluding lymphocytes and granulocytes, we developed a strategy based on staining red cell-lysed peripheral blood and gating cells bearing myeloid markers and physical parameters of large mononuclear cells. RESULTS Phenotypic analysis within the My-APC gate showed three distinct populations. The largest fraction was constituted by CD14+ monocytes that extended into the other two populations, each expressing gradually lower levels of CD14 surface antigen along with increasing levels of CD16 and CD2, respectively. The CD16 and CD2 expression patterns extended from CD16+CD14+ or CD2+CD14+ double- positive intermediate cells toward each single positive subset, but they were reciprocally exclusive. Interestingly, CD2+CD14- cells within the My-APC gate were equivalent to myeloid dendritic cell precursors (pre-DC) defined previously by the absence of lineage markers and expression of HLA-DR and myeloid markers. Phenotypic analysis of each population revealed differences in the expression of costimulatory molecules and CD62L. CONCLUSIONS This novel analytical approach allowed us to distinguish circulating My-APC in three subsets and to identify relationships between monocytes and other related myeloid populations including DC.

Collection of circulating progenitor cells after epirubicin, paclitaxel and filgrastim in patients with metastatic breast cancer.

The efficacy of high-dose chemotherapy (HDC) and circulating progenitor cell (CPC) transplantation in metastatic breast cancer (MBC) relies mainly on giving this treatment after a response to conventional induction chemotherapy has been achieved. For this reason an optimal mobilization regimen should be therapeutically effective while minimizing the number of leucaphereses required to support the myeloablative therapy. The combination of an anthracycline and paclitaxel in chemotherapy-untreated MBC has produced impressive response rates. We evaluated the CPC-mobilizing capacity of the combination epirubicin (90 mg m(-2)) and paclitaxel (135 mg m(-2)) followed by filgrastim (5 microg kg(-1) day(-1)) starting 48 h after chemotherapy administration in ten patients with MBC who were eligible for an HDC and CPC transplantation programme. Leucaphereses were performed by processing at least two blood volumes per procedure at recovery from neutrophil nadir when CD34+ cells in the peripheral blood exceeded 20 microl(-1). In most patients (six out of 10) more than 2.5 x 10(6) CD34+ cells kg(-1), a threshold considered to be sufficient for haematopoietic reconstitution, were collected with a single apheresis. In the remaining four patients an additional procedure, performed the following day, was enough to reach the required number of progenitors. These data suggest that the epirubicin-paclitaxel combination, besides being a very active regimen in MBC, is effective in releasing large amounts of progenitor cells into circulation.

Hormonal modulation of brain tumour growth: a cell culture study

SummaryTissue samples derived from two neuroepithelial tumours and five meningiomas were obtained at surgery from seven patients and cultured in order to study the effect of dexamethasone (DEX) and testosterone acetate (TA) on cell proliferation.Glucocorticoid and androgen receptors (GR, AR) were determined both on tissue samples (7 cases) and on five out of the seven cell cultures obtained by tumours.GR and AR were present respectively in 5 and in 4 out of the tumour specimens assayed and in 4/5 and 2/3 of the tested cell cultures.DEX activity on cell growth was tested on six cell cultures. Four of them showed a significant growth inhibition at the highest drug concentration. On the contrary, a significant growth stimulation was observed in four out of the five cultures, where GR were present, using low hormone concentrations. Treatment with pharmacological doses of TA caused a significant cytotoxicity in all the tested cultures. Low TA concentrations inhibited cell growth in one out of the two cell cultures which contained AR, but were ineffective in cultures lacking AR.Our preliminary results suggest a possible role in growth regulation by DEX and TA in intracranial tumours, on the basis of the presence of specific hormone receptors.