e21522 Background: Immune-related adverse effects (irAE´s) of immune-checkpoint inhibitors (ICIs) have been linked with a better treatment response in melanoma patients, especially cutaneous toxicities. However, little is known regarding other irAE´s which is important as they can be used as clinical markers of an adequate therapeutical response. Methods: We conducted a retrospective study on patients who were diagnosed with melanoma and received treatment with ICI´s between January 2015 until December 2021, immune related adverse events and their relationship with overall survival in melanoma patients treated with ICIs was the main objective of this study. Results: 53 records of patients with advance melanoma treated with ICIs between january 2016 to december 2021, demographic characteristics were as follow: 64.2% were male, mean age at diagnoses was 60.3 years, 41.5% had smoking history and 15.1% were Jewish. At diagnosis 73.6% of patients had a good functional status (ECOG 0-1). The most common histological subtypes were epithelioid (34%), and nodular (22.6%). Lung metastases was the most common affected site (49.1%), followed by brain 43.4% and non-regional nodes 42.5%. BRAF mutations was determined in 81.1% of the biopsies and 36% of them being V600E mutation. ICI´s was the preferred first line treatment in 83% of cases, median number of administered cycles were 6 (range 1-54 cycles), 60.4% of patients received pembrolizumab, 37.7% nivolumab plus ipilimumab, 20.8% nivolumab monotherapy and 5.7% ipilimumab. Throughout the studied period IrAE´s were reported in 34% of patients with 66.7% of them being grade 1-2 and 33.3% grade 3-4. The most common IrAE’s: vitiligo 38.8%, hypothyroidism22% and 3.8% pneumonitis. Median PFS at 12 months and OS was significantly better in the group of patients with irAE´s: Patients who develop an irAE´s are 7 times more likely to be disease free at 12 months and 4.1 times more likely to have a longer OS regardless of severity and type of toxicity. The impact of developing irAEs is significantly important for PFS (HR: 11.9, CI 95%: 3.28-4.71) as median PFS was not yet reached in this group. Conclusions: Development of irAEs is associated with favorable outcomes to ICIs with patients being 7 times more likely to be 12-month disease free and 4.1 times more likely to have a longer OS. irAEs can be used as clinical markers of an adequate treatment response.[Table: see text]

e14570 Background: Cancer in Mexico represents the third cause of death nationally. Immunotherapy agents have changed management and prognosis of cancer patients. Immune-checkpoint agents are now being used as both first- and second-line treatment improving cancer patient prognosis, nevertheless it is not always accessible. Methods: Retrospective review of patients diagnosed with any type of cancer that received immunotherapy during their disease course from the last 5-years. We present the most common malignancies, immunotherapeutic regimens received, population characteristics and survival analysis. Results: 130 records of patients ≥18 years that received immunotherapy were included. 52.3% female with mean age of 59 years (range, 22-89 years), 48.5% former smokers (average pack/year of 22.5) and 31.5% asbestos exposure. 53.1% were ECOG 0 and 82.3% clinical stage IV. 62.3% of cases were lung adenocarcinoma, followed by lung epidermoid carcinoma (13.1%) and 10% small-cell lung carcinoma. Immunotherapeutic agents used included nivolumab in 63.1%, pembrolizumab 12.3%, nivolumab + ipilimumab 8.5%, durvalumab 6.2%, pembrolizumab + ipilimumab 4.6%. 36.2% of patients received immunotherapy as second line treatment, 30.0% as third and 23.8% as first line treatment. The best Response Evaluation Criteria in Solid Tumors (RECIST) was RECIST 3 in 46.2% followed by RECIST 0 with 25.4%. Median progression-free survival (PFS) was 5 months (95% CI; 3.883-6.117) and median OS of 13 months (95% CI; 10.210-15.790). Analysis per immunotherapy on PFS (p = 0.0414) and OS (p = 0.0046) demonstrated pembrolizumab had the longest median PFS with 19-months and OS with 22-months. Analysis between tumor types was significant for both PFS (p = 0.0018) and OS (p = 0.0090) with melanoma having the longest median PFS (42-months) and OS (46-months). Conclusions: Immunotherapy has changed cancer management; however, its use depends on specific biomarkers and adequate patient selection. Not all patients benefit from immunotherapy, in a country like ours where resources are limited, it is of vital importance to properly select candidates for immunotherapy. Even though, all patients had an FDA-approved indication at the time of receiving immunotherapy, PFS and OS are not as significant as Phase 3 studies demonstrate, this may be due to late stages, advanced ECOG, correct biomarkers availability and adequate patient selection. It is important to mention that about 40-60% of patients with immunotherapy do not respond adequately. In our study, because there is more evidence with pembrolizumab, the patients who received it were better chosen and therefore there was an impact in PFS and OS. Immunotherapy selection also depends on physician experience to the different immunotherapy regimens.