Gandini, Sara

3036 Background: The presence of HER2 expressing (HER2+) circulating tumor cells (CTCs) occurs often in metastatic breast cancer (MBC) patients (pts). We have previously showed that the ratio among CTCs expressing high level of HER2 and the total number of HER2+ CTCs (circulating HER2 ratio, cHer2 ratio) has a prognostic role in MBC patients. Here we further investigate the role of the cHER2 ratio in the process of metastatic spread. Methods: Under IRB-approved study we prospectively analyzed blood samples of patients with MBC enrolled before starting a new line of therapy. Samples were collected from pts treated at Northwestern University (Chicago, IL) between 2016 and 2020. CTCs were enumerated through CellSearch (Menarini Silicon Biosystems, Bologna, Italy) and characterized for HER2 expression using the CellSearch CXC Kit. HER2+ CTCs were divided in 3 different categories (1+,2+,3+) leaning on fluorescence intensity. Pts with <5 CTCs (stage IV indolent) were excluded from the analysis. The cHER2 ratio, defined as the sum of 2+ CTCs and 3+ CTCs divided by the total number of HER2+ CTCs, was used to split the remaining pts in 2 different cohorts: cHER2 ratio high (> 0.75) (cHER2high) and cHER2 ratio low (≤0.75) (cHER2low). The frequency of each metastatic site (i.e. liver, lung, central nervous system, bone, lymph nodes, skin/soft tissue, serosa) and the total number of different sites involved (1-7, ≤2 and >2 sites) were compared among the two sub-populations and analyzed through Fisher exact test. Results: Out of 98 pts enrolled, 77 were classified as cHER2low and 21 as cHER2high. We observed a higher frequency of oligometastatic pts (≤2 sites involved) in the cHER2high cohort (16, 76%), compared to only 29 (37%) in the cHER2low (p<0.005). Moreover, the cHER2 ratio was associated with a tropism toward specific sites of disease spread with higher incidence of liver, lung and lymph nodes metastases in the cHER2low cohort (p<0.05). No other statistical associations were observed in respect of specific organ tropism. The frequency of involvement for each metastatic site among the two cohorts are reported in the table. Conclusions: Measuring CTCs enumeration and HER2 expression we identified two cohorts, cHER2high and cHER2low, associated with distinct patterns of metastatic spread. The cHER2low pts were correlated to multiple sites of metastatic involvement, with particular tropism toward liver, lung and lymph nodes. These results confirm the prognostic role of the cHER2 ratio, suggesting a peculiar biological meaning of the HER2+ 1+ CTCs.[Table: see text]

Abstract Abstract 880 Pulmonary marginal zone lymphoma is a distinct subgroup of B-cell non-Hodgkin's lymphomas originating from the bronchial-associated lymphoid tissue (BALT) and characterized by an indolent clinical course. Here we present the data of the IELSG-28 study of the International Extranodal Lymphoma Study Group (IELSG) on primary pulmonary lymphoma patients. Clinical records and histological material of 186 patients diagnosed with pulmonary marginal zone lymphoma from December 1986 to June 2009 were collected. The pathology was reviewed centrally and the diagnosis was confirmed in 180 (96%) patients. The median age at diagnosis was 62 (30 – 88). The majority of the patients (149/180) had localized disease at diagnosis with a good performance status (0–1) and low prognostic index (IPI 0–2). Eighty-one patients (45%) received local treatment, including surgery (74%) or radiotherapy (4%). Ninety-nine patients with advanced stage disease or incomplete surgical resection received an additional systemic treatment. Most of these patients (66; 66%) received an alkylating containing regimen, 22 (22%) patients were treated with an anthracycline containing regimen and 29 (29%) received the anti-CD20 monoclonal antibody in combination with chemotherapy. With a median follow up of 67 (range 1–256) months, 47/180 patients (26%) experienced disease progression. (median time to progression 30 months, range 0–109). Progression free survival analysis showed a trend in favour of patients treated with immuno-chemotherapy versus those receiving chemotherapy alone (HR 0.53–95%CI: 0.21, 1.33), while no difference in terms of OS and PFS was observed between patients receiving systemic anthracycline or alkylating containing regimens. In twenty five cases a specific PCR-assay was carried out for detecting the presence of Achromobacter (Alcaligenes) xylosoxidans. The presence of Achromobacter was detected in 50% of patients. Our results confirm that local therapy (surgery or radiotherapy) is the treatment of choice for patients with localized disease. Chemotherapy has to be considered in case of relapse, incomplete surgical excision or advanced disease. In this setting, alkylating containing regimens plus rituximab is the most effective option. Further studies are ongoing to confirm the relevance of infection/colonization with Achromobacter (Alcaligenes) xylosoxidans for pathogenesis of BALT lymphoma. Disclosures: No relevant conflicts of interest to declare.

Abstract Primary lymphoma of the lung is a rare entity. Clinical features, optimal treatment, role of surgery and outcomes are not well defined, and the follow‐up is variable in published data. Clinical data of 205 patients who were confirmed to have bronchus mucosa‐associated lymphoid tissue lymphoma from December 1986 to December 2011 in 17 different centres worldwide were evaluated. Fifty‐five per cent of the patients were female. The median age at diagnosis was 62 (range 28–88) years. Only 9% had a history of exposure to toxic substances, while about 45% of the patients had a history of smoking. Ten per cent of the patients had autoimmune disease at presentation, and 19% patients had a reported preexisting lung disease. Treatment modalities included surgery alone in 63 patients (30%), radiotherapy in 3 (2%), antibiotics in 1 (1%) and systemic treatment in 128 (62%). Patients receiving a local approach, mainly surgical resection, experienced significantly improved progression‐free survival ( p = 0.003) versus those receiving a systemic treatment. There were no other significant differences among treatment modalities. The survival data confirm the indolent nature of the disease. Local therapy (surgery or radiotherapy) results in long‐term disease‐free survival for patients with localized disease. Systemic treatment, including alkylating‐containing regimens, can be reserved to patients in relapse after incomplete surgical excision or for patients with advanced disease. Copyright © 2015 John Wiley & Sons, Ltd.