Weinmann, Dena

8094 Background: Patients with extensive-stage small cell lung cancer (ES-SCLC) who progress after platinum-based chemotherapy plus immunotherapy have limited options. Whether adding lurbinectedin while continuing immune checkpoint blockade at relapse improves outcomes is unknown. We report results for the platinum-resistant cohort (progression ≤3 months from last chemotherapy) of MC1923. Methods: MC1923 is a phase II trial using a Simon optimal two-stage design. Patients were assigned to a starting dose of durvalumab 1500 mg IV plus lurbinectedin 3.2 mg/m 2 IV on Day 1 of 21-day cycle. The primary endpoint was the 6-month progression-free survival rate (PFS6). Accrual continued to 22 eligible patients if ≥2/9 achieved PFS6; the regimen would be considered promising if ≥7/22 (32%) were alive and progression-free at 6 months. Secondary endpoints included adverse events (AEs), objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Results: Twenty-two patients enrolled (02/04/2022–05/21/2025); all were eligible and treated. Median age was 66 years; 32% were male; ECOG performance status was 0 in 9% and 1 in 91%; 96% had prior atezolizumab. Median cycles delivered were 4 (range 1–13). PFS6 was 4/22 (18.2%; 95% CI, 7.5–44.1%), below the prespecified threshold. Median PFS was 3.1 months (95% CI, 1.6–5.3). ORR was 13.6% (3/22; all partial responses; 95% CI, 2.9–34.9%). At data cutoff (12/18/2025), 4 patients were alive; median follow-up was 16.8 months (range 5.5–39.6). Median OS was 7.4 months (95% CI, 4.3–18.6) and 1-year OS was 33.1% (95% CI, 17.6–61.9%). One (1) patient discontinued treatment with durvalumab due to AE. No treatment-related Grade 5 AEs occurred; Grade 3–4 AEs at least possibly related to treatment occurred in 32% (7/22); Grade 4 AEs occurred in 5% (1/22), all hematologic. Most common Grade 3 AEs were decreased neutrophils and white blood cells (each 9%). Conclusions: Durvalumab plus lurbinectedin demonstrated manageable toxicity in platinum-resistant ES-SCLC after chemoimmunotherapy but did not meet the prespecified PFS6 efficacy threshold, supporting the need for alternative strategies in this high-risk population. Clinical trial information: NCT04607954 .

Abstract Extra-neural metastasis in recurrent medulloblastoma, carries a potentially fatal outcome. No robust salvageable therapeutic strategy is present, for these clinical phenotypes. We present an 18-year male, who presented at the age of 8 years as a standard risk medulloblastoma and was treated with chemotherapy (as per ACNS0331) followed by craniospinal radiation. At first recurrence in the thoracic spine, he underwent a gross total resection of the tumor, followed by high-dose stem cell chemotherapy and focal radiation. The 2nd recurrence which occurred in the thecal sac 9 years later was treated with metronomic anti angiogenic chemotherapy with outcome a complete radiographic response. Third recurrence occurred in the liver, bone marrow, multiple bones of axial skeleton and sacrum. Molecular interrogation of the lesions showed a (non-WNT / non-SHH subtype) with absence of MYC or MYCN amplification or any other clinically significant biological aberration. He received local radiation to tumors, following which he developed severe myelosuppression. A bone marrow aspirate and biopsy showed greater than 95% involvement with medulloblastoma cells. He was treated with irinotecan and temozolomide. A dramatic response was noted after one cycle (with PET and MRI), with bone marrow involvement of less than 1%. He continues with that therapy. To-date no defined molecular profile is predictive of extra neural metastasis, and has been likened to a fatal outcome, most patients being declared for hospice care. Our patient with this unique clinical outcome, warrants extensive evaluation of these rare clinical phenotypes including methylation profiling and RNA sequencing, which might suggest, certain molecular aberrations which correlates with good response, even in these biologically aggressive variants.

Abstract Peritoneal Carcinomatosis of anaplastic ependymoma is not a previously reported entity. The authors report on a child with multiple successfully treated brain and spine disease occurrences who subsequently develops carcinomatosis of the abdomen and no evidence of CNS recurrence. Ependymoma accounts for up to 10% of childhood CNS tumors diagnosed in the United States with a median age of 51–71 months. Typical locations are based on age. Disease is typically treated with surgical resection followed by radiation. The role of chemotherapy has not been proven but currently being examined with open clinical trials. We will describe patient’s presentations, clinical treatment and recurrence with subsequent treatment and outcome at time of meeting.