e12574 Background: Currently there are no primary cultures or cell lines derived from patients with breast cancer and obesity. It has been postulated that breast cancer in obese women behaves differently as it does in non-obese women, as is composed of distinct biological features, as was generated in a different metabolic environment, as well as pertains to a different prognosis and different response to chemotherapy, lower rates of overall survival and a greater probability of recurrence. By creating a primary breast cancer culture bank of breast cancer tumors from women with obesity (BMI > 30kg/m2), we will establish a cell line exclusive to obese women in Mexico, where targeted therapy may be tested and treatment may be individualized depending on the characteristics of the patient. Methods: This study recruited 32 women with breast cancer and a BMI > 30 kg/m2, matched by 6 controls with are non-obese women with breast cancer. Elegibility criteria was determined by women with breast cancer confirmed by pathology, who had not been subjected to prior treatment regarding the neoplasm. The breast cancer removing surgeries and the patients were selected from the ABC Medical Center in Mexico City and all procedures were approved by the research and ethics committee of the hospital in question. Results: Through extensive communication a cooperative protocol was established between the departments of surgery, oncology, pathology and nursing to coordinate efforts and be able to take a 2 – 5 mm sample of the breast tumor removed from the patient. To be able to distinguish cancer cells from non-cancer cells (epithelial cells, fibroblasts, adipocytes) the Hayflick limit was be utilized. Once a primary breast cancer culture was established, 12 million cells will be injected into the subscapular area of athymic, nu-nu mice to be able to monitor tumoral growth in vivo and conduct a subsequent cellular analysis, determining it still pertains to the same characteristics of the tumor from which it was obtained. Conclusions: A primary breast cancer culture repository from patients with a BMI > 30 kg/m2 was established. This is the first primary breast cancer culture for both Mexican and obese women with breast cancer, the first in vitro method of analysis of specific characteristics typical of the Mexican population. Translational research may now be conducted on these new tumoral cultures to create individualized therapy for women with the distinct, aforementioned characteristics.

e20565 Background: Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer. Prognosis is generally poor, with a median overall survival (mOS) of approximately 12 months. MPM appears to be directly linked to immunosuppressive mechanisms, leading to use of checkpoint inhibitors for patients with this disease. Methods: We performed a retrospective chart review of patients with MPM at our institution between January 2015 to December 2020. All patients were over 18 years at the time of diagnosis of mesothelioma, a total of 8 patients were retrieved from the pathology database of The American British Cowdray Medical Center. The clinical-pathologic features collected were sex, age, performance status, risk factors, pTNM stage (AJCC 8th edition), histology type, sintomatology of onset, metastases sites and treatment. Clinical response rate and other outcomes were assessed. Descriptive statistics were used to describe a patient's demographic and disease characteristics. Results: 8 patients, aged 49 to 71 years (median of 65) at diagnosis of MPM were treated in our center. Both sex presented 4 patients in total. An identifiable risk factor was recorded in 4 patients (2 with asbesto exposure and 2 with heavy smoking). 7 patients (87.5%) had PS 0 or 1, the remaining has PS 2. The clinical stage at diagnosis was unresectable in 7 patients. 3 patients were assessed with PD-L1 expression (SP263 or 22C3), only one with expression of 20%. All patients received at least one scheme of chemotherapy prior to receiving immunotherapy, 25% received bevacizumab/platinum/anti-folate agents. Checkpoint inhibitors were introduced as a second line in 20% and in 80% has a third or more lines. Pembrolizumab was used in 20% and Nivolumab in 80%. The tumor responses with immunotherapy were as follows: partial response 12.5%, stable disease 75% and progressive disease 12.5%. Median progression-free survival of the first line treatment was 18.9 months (4.6-33.6 months), and for the line with checkpoint inhibitors was 11.2 weeks (7-21.2). In the full cohort, mOS was 37.0 months (95% CI:14.5-39.6). According to histology, the mOS for epithelioid-type was 36.6 months and for biphasic-type was 14.6 months (p = 0.42). mOS was 37.0 months for the group with immunotherapy and 15.0 months for those with standard chemotherapy (p = 0.14). The most frequently reported immune mediated adverse events were hypothyroidism and colitis (each one with one patient). Conclusions: In this real-world analysis, mOS was superior to those obtained in the MAPS2 trial (mOS 11.9 months), despite the fact that 80% of the population that received immunotherapy was in third or more lines. Limitations include limited numbers of patients, retrospective review, single institution, and inclusión of many heavily pretreated patients. Also molecular and immunohistochemical results such as PD-L1 status were only available on a limited number of patients.

327 Background: Advanced gastric cancer (GC) is a disease with high morbidity and poor prognosis. We hypothesize that different sites of metastasis have different impact in terms of symptoms and complications. We sought to evaluate if site specific morbidity in our patients impacted treatment and survival. Methods: Medical records from patients with advanced GC treated from Jan 2005 to Dec 2015 were retrospectively reviewed. Morbidity was defined as having any symptom by metastases in a specific site. OS was estimated by Kaplan Meier method and compared by Log-rank test. P value < 0.05 was considered significant. Results: We included 180 consecutive patients, median age at diagnosis was 56 years (21-90), 55% were women. Most common sites of metastases were: peritoneum 76.1%, non-regional lymph nodes 38.9%, liver 22.8%, lung 26.7%, bone 9.4% and ovary 12.8%. Regarding morbidity, at diagnosis 68% of patients presented morbidity by the primary tumor: obstruction 56%, bleeding 27%, obstruction and bleeding 3%, other 14%. Disease by peritoneum caused morbidity in 30%, by lung in 8%, by ovarian in 4.4%, by lymph nodes in 3.3%, and by other sites in 5.6% of patients. OS in the global cohort was: 3.53 months (2.2 to 4.8), nevertheless by univariate analysis we found that OS was affected by morbidity at some sites as it is show in table. More patients with peritoneal morbidity could not receive treatment vs those without peritoneal morbidity (p = 0.042). Conclusions: We found that morbidity in peritoneum, lung and ovary adversely affected prognosis of patients with advanced GC. Moreover, peritoneal morbidity preclude patients from receiving oncological treatment. [Table: see text]

e22517 Background: there are few reported series n women with breast cancer (BC) and COVID-19, a better prognosis has been observed, with a lower rate of hospitalization and mortality than other neoplasms. Methods: We conducted a restrospective, non-experimental, observational, single center, study with a sample of 69 patients with BC who had presented COVID-19, in the period between March 2020 to August 2021. Clinicopathological characteristics of patients with BC were compared between severe and non-severe covid 19 groups, as well as hospitalized and non-hospitalized patients. An analysis of possible risk factors associated with severe disease and hospitalization was performed. Results: 69 cases were reported, median age 52y, mean BMI 25.2, ECOG 0-1: 97%. Smoking history in 24%, diabetes and hypertension were the most frequent comorbidities. The most frequent histology was ductal carcinoma in 80.6%, 73.8% showed ER + and 69.3% PR +, HER2 was overexpressed in 9.2%. The early stages predominated, I 22 (31.3%), II 25 (37.3%), III in 12 (17.9%) and IV in 6 (9%). The most frequents symptoms of COVID-19 were fatigue 70.1%, fever 65.7%, cough 59.7%, headache 56.7%, hyposmia 47.8%, dysgeusia 38.8%. A total of 53 (76.8%) mild cases, 14 (20.3) severe cases and 2 (2.9%) critical cases were registered. The 89.9% (62 patients) were treated as an outpatient basis, while 7 (10.1%) required hospitalization. Active treatment (< 45 days) at the time of COVID-19 was hormonal therapy 36 (50.7%), chemotherapy 11 (16.4%), anti-HER2 in 3 (4.5%), immunotherapy in 1.5%, targeted treatment in 4 (6.0%), surgery in 7 (10.4%) and radiotherapy in 1 (1.5%) patient. When comparing the severe and non-severe groups, as well as hospitalized versus non-hospitalized, we observed no difference between the clinicopathological characteristics. Then, we serch for possible risk factors, in wich, surgery in a period of less than 3 months increases the risk of severity OR 1,297 (95% CI 1,112-1,514), the risk of hospitalization increased in the triple negative subgroup OR 1,143 (95% CI, 1,035- 1,262), surgery less than 3 months OR 1,116 (1,014-1,229) and chemotherapy less than 45 days OR 1,217 (95% CI, 1,024-1,447). Conclusions: In patients with BC, the prevalence of severe or critical COVID-19 was 23% and the hospitalizacion rate 10%. No patient died from this infection. The clinical and pathological characteristics of BC do not appear to increase the risk of severe COVID-19 or the rate of hospitalization. Surgery performed in a period of less than 3 months is marginally associated with an increased risk of severe disease. Chemotherapy, targeted therapy, and immunotherapy do not modify the risk of severe disease; however, higher Ki 67, triple negative subgroup, surgery and chemotherapy showed a slight increase in risk of hospitalization.

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