Hernando, Jorge

662 Background: Alkylating-based chemotherapy (ALK) is one of the main treatments used in patients with advanced pancreatic neuroendocrine tumors (PanNETs). Its use has been associated with an increased risk of grade progression and acquisition of a hypermutator phenotype, associated with frequent alterations of the mismatch repair (MMR) genes. This suggests a potential benefit of immune checkpoint inhibitors (ICI) that are otherwise ineffective in ALK-naïve PanNETs, which are mostly hypomutated. We aimed to describe the efficacy of ICI in patients with advanced PanNET pretreated with ALK. Methods: We assembled an international retrospective cohort of patients with advanced PanNET who received at least one cycle of ICI, and who had previously received at least 3 months of ALK. Patients with poorly-differentiated neuroendocrine carcinoma were excluded. The primary endpoint was progression-free survival (PFS) and the secondary endpoint was the objective response rate (ORR). The impact of tumor mutational burden (TMB, high being defined by >10 mut/Mb) and MMR alterations (mutations or IHC) was explored. Results: We included 39 patients (median age 58.7, male sex 62%). All PanNETs were progressive at baseline and presented a median of 3 (IQR, 2-4) metastatic sites. Tumors were predominantly classified as G2 (47%) or G3 (42%), with a median Ki-67 of 18.5% (IQR, 12-35). 23/27 patients with tumor tissue or ctDNA NGS testing had high TMB (median, 35 mut/Mb; IQR, 24-106) and 12/22 had MMR alterations. Patients had previously received an average of 14 cycles (IQR, 7-25) of ALK (temozolomide 78%, streptozotocin 18%, dacarbazine 4%), which had yielded objective response in 72% of cases. In addition, patients had received a median of 4 (IQR, 3-5) other treatments (including platinum drugs in 80% and PRRT in 51%). ICI mainly consisted in an anti-PDL1/PD1 + anti-CTLA4 combination (85%) or a monotherapy (15%), with a median of 3 (IQR, 2-8) cycles. The ORR was 18% and the disease control rate was 46%. Median PFS was 2.8 months (95% CI, 0.62-4.96) and 6-month PFS rate was 31%. 19% of patients had grade 3-4 toxicity. Patients with high TMB had higher ORR (30% vs. 0%, p=0.03) and longer median PFS (4.9 vs. 2.1 months, p=0.004) compared with patients with low/unknown TMB. Patients with altered MMR had higher ORR (42% vs. 7%, p=0.02) and longer median PFS (8.9 vs. 2.5 months, p=0.014) compared with patients with no/unknown MMR alterations. Conclusions: While ICI shows limited efficacy in unselected patients with advanced PanNETs pretreated with ALK, it may be an effective treatment option in case of high TMB and MMR alterations.

We conducted a retrospective/prospective worldwide study on patients with neuroendocrine neoplasms (NENs) and a molecularly proven SARS-CoV-2 positivity. Preliminary results regarding 85 patients of the INTENSIVE study have been published in 2021. Now we are reporting the 2-year analysis.Here, we are reporting data from consecutive patients enrolled between 1 June 2020, and 31 May 2022. Among the 118 contacted centers, 25 were active to enroll and 19 actively recruiting at the time of data cut-off for a total of 280 patients enrolled. SARS-CoV-2 positivity occurred in 47.5% of patients in 2020, 35.1% in 2021, and 17.4% in 2022. The median age for COVID-19 diagnosis was 60 years. Well-differentiated tumors, non-functioning, metastatic stage, and gastroenteropancreatic (GEP) primary sites represented most of the NENs. COVID-19-related pneumonia occurred in 22.8% of the total, with 61.3% of them requiring hospitalization; 11 patients (3.9%) needed sub-intensive or intensive care unit therapies and 14 patients died (5%), in 11 cases (3.9%) directly related to COVID-19. Diabetes mellitus and age at COVID-19 diagnosis > 70 years were significantly associated with COVID-19 mortality, whereas thoracic primary site with COVID-19 morbidity. A significant decrease in both hospitalization and pneumonia occurred in 2022 vs 2020. In our largest series of NEN patients with COVID-19, the NEN population is similar to the general population of patients with NEN regardless of COVID-19. However, older age, non-GEP primary sites and diabetes mellitus should be carefully considered for increased COVID-19 morbidity and mortality. Relevant information could be derived by integrating our results with NENs patients included in other cancer patients with COVID-19 registries.

e16205 Background: Data about neuroendocrine neoplasms (NENs) patients with SARS-CoV-2 are scanty and specific indications for clinical practice are missing. Our aim is to create an international registry about NENs patients affected by SARS-CoV-2 positivity to give a worldwide representation of the situation. Methods: This is an observational retrospective/prospective multicenter survey based on a direct email invitation. All types of NEN are eligible except SCLC and MiNEN. Patients fulfilling the inclusion criteria from March 1st, 2020 up to the end pf pandemic will be recruited. Electronic CRFs are filled out using the REDCap database. Local Institutional Review Board approval is required before data entry. Results: Eighty-one centers, 24 in and 57 outside Italy, representing 39 countries and 5 continents, were contacted. Fourteen centers did not respond and 15 declined the invitation. Among the remaining 52, 6 centers are currently recruiting and 8 are active but not recruiting yet. As of the current abstract submission deadline, 67 patients have been included, mostly GEP-NET (75%), non-functioning (86%), metastatic (85%) and on active treatment [47% somatostatin analogs (SSAs), 10% everolimus, 12% tirosin-kinase inhibitors (TKIs), 10% peptide receptor radionuclide therapy (PRRT), 15% chemotherapy]. Median age at NEN diagnosis was 57 years whilst the median age at SARS-CoV-2 diagnosis was 62 years. Almost all patients reported COVID-19-related symptoms, more commonly fever (67% of patients), cough (55%) and dyspnea (51%), in 28% of cases exertional and in 22% at rest. More than one third of patients (n, 24) had a pneumonia. The most common therapies for COVID-19 were antibiotics, steroids and hydroxychloroquine. Eleven patients (16%) needed oxygen therapy, three (4%) sub-intensive care and none intensive care. Fifty-six patients (84%) clinically recovered, six (9%) with sequelae, whereas five (7%) died. Among these latter 4 had a NET and 1 a NEC, and no patients have been receiving chemotherapy. With regard to the anti-tumor therapy no change occurred in 66% of patients, temporary interruption in 30%, and definitive discontinuation in 3%, 2% missing. Conclusions: Most of the NEN patients completely recovered from COVID-19, in many cases without any anti-tumor therapy adjustment. No clear correlations were observed with type, primary site and treatment of NEN. The recruitment is ongoing.