Meyer, Haley M

164 Background: Lurbinectedin (L) is a novel inhibitor of oncogenic transcription that was granted accelerated approval by the Food and Drug Administration in June 2020 for the treatment of metastatic small cell lung cancer (SCLC) following disease progression on or after platinum-based chemotherapy (PBC). Prostatic small cell or neuroendocrine carcinoma (SC/NEPC) is a high-grade, invasive malignancy that accounts for < 1% of all prostate cancers. SC/NEPC is distinct from prostatic adenocarcinoma and behaves similar to SCLC. NCCN guidelines for SC/NEPC recommend following the SCLC treatment guidelines. Using these guidelines, L may be used as a second-line treatment in patients (pts) with SC/NEPC who progress on or after PBC. We aimed to characterize the baseline characteristics, clinical course and therapeutic outcomes of pts treated with L for SC/NEPC. Methods: After IRB approval, 18 cases were gathered from 4 academic oncology centers. Baseline patient data, prior treatments and L treatment outcomes, including best radiographic and serologic responses, overall survival (OS), progression-free survival (PFS) and treatment toxicity were assessed. The Kaplan-Meier method was used to calculate OS and PFS from the L start date. Clinical benefit rate (CBR) included pts with complete response (CR), partial response (PR) and stable disease (SD) on imaging. Results: At the time of first L dose, all had metastatic disease with 2-6 distinct sites of metastases, most commonly bone (14/18, 77.8%), lymph nodes (14/18, 77.8%) and liver (13/18, 72.2%); median age was 63.5 (Range: 53-84); 11 pts (61.1%) had an ECOG 0-1; 4 pts (22.2%) had an ECOG of 2-3. The median total number of systemic therapies administered prior to L was 4 (Range: 2-7). All pts received PBC prior to L. The most common dose of L prescribed was 3.2 mg/m2 every 21 days (15/18, 83.3%). Androgen deprivation therapy was administered in conjunction with L in 9 pts (50%). The median number of cycles of L was 5 (Range: 1-10). L was discontinued due to toxicity in 1 patient (5.6%), disease progression in 10 pts (55.6%), transition to hospice in 2 pts (11.1%), 3 pts (16.7%) died while receiving treatment (not due to L toxicity), and 2 pts (11.1%) remained on L at the time of data reporting. The median OS and PFS from date of first L dose was 6.01 months (0.23 – 16.69) and 3.35 months (0.16 – 7.79), respectively. CBR was 9/16 (56.3%) with partial response in 5 pts (31.3%), stable disease in 4 pts (25%), and progressive disease in 7 pts (43.8%). Two pts did not have post-treatment imaging available to assess response. There were no hospitalizations for L treatment related adverse events (tRAE). The most common tRAE were grade I and II fatigue and anemia; 9 pts (50%) experienced no tRAE. The only grade IV toxicity was neutropenia in 3 pts (16.7%). Conclusions: L is a well-tolerated and active treatment option for patients with SC/NEPC. Prospective studies are needed to determine the role of L in the treatment of SC/NEPC.

12051 Background: The combination of ipilimumab and nivolumab (Ipi-Nivo) is a standard of care regimen in many malignancies. However, immune-related adverse events (irAE) are common and are of great concern, especially when treating the elderly population. This subgroup of patients may be at greater risk for serious irAEs and be less able to tolerate the potential treatment side effects. We sought to retrospectively evaluate our experience treating elderly patients ≥ 80 years with Ipi-Nivo to characterize adverse events. Methods: A retrospective chart review of the electronic medical records of all patients treated with Ipi-Nivo at the Mayo Clinic Health System was performed. Patients with any solid tumor who received their first dose of Ipi-Nivo at the age of ≥ 80 were included. Records were analyzed for baseline characteristics, cancer type, toxicity, and response to therapy. Differences between continuous and categorical variables were assessed using the students’ t-test and the chi-squared test, respectively. Overall survival (OS) was estimated using the Kaplan-Meier method. Cox proportional hazard models assessed the relative contribution of factors to survival after treatment. P values < 0.05 were considered statistically significant. All analyses were performed using SAS V.9.4. Results: Forty-six patients met inclusion criteria, 13 females and 33 males. Median age of first dose was 83 (Range: 80 - 94). Sixty-seven percent had an ECOG performance status (PS) 0-1 and 33% had an ECOG PS 2-3. Thirteen (28.3%) patients received 4 cycles of Ipi-Nivo. Cancers included: 18 (40%) melanomas, 10 (21%) mesothelioma, 9 (19.5%) lung cancers, and 9 (19.5%) other types. Thirty-one patients (67%) developed at least one irAE. Of the irAEs, 8 (17.4%) were grade 1, 20 (43.5%) were grade 2, 14 (30.4%) were grade 3, and 3 (6.5%) were grade 4. Systemic steroids were used in 29 (63%) patients. Twenty-six (56.5%) patients were hospitalized for any cause, and 12 (26.1%) were hospitalized due to an irAE. Of the 26 patients hospitalized during treatment, 19 (73%) died within 1 year of discharge; 11 (42%) died within < 1 month of discharge and 3 (12%) died within 1-3 months of discharge. Median OS from the date of first Ipi-Nivo dose was 14.6 months in the ECOG PS 0-1 and 6.5 months in the ECOG PS 2-3. ECOG PS of 0-1 was associated with a significantly decreased risk of mortality (HR [hazard ratio] 0.33, 95 % CI [confidence interval]: 0.15-0.70; p=0.0025) compared to ECOG PS of 2-3. Conclusions: This is the first analysis to evaluate the outcomes of Ipi-Nivo in patients ≥ 80 years. Approximately 60% of the patients required systemic steroids and a quarter were hospitalized with grade 3-4 irAEs. As expected, patients with ECOG PS 2-3 did significantly worse than ECOG PS 0-1. Ipi-Nivo should be used with caution in patients ≥ 80 years.