{
  "abstract": "Background In May 2024, the FDA approved tarlatamab, a Delta-like ligand (DLL3)/CD3-targeted bispecific T-cell engager, for patients with extensive-stage small cell lung cancer (SCLC) with disease progression following platinum-based chemotherapy and at least one other prior line of therapy. We aim to examine the cellular immune cell profile changes seen in patients receiving this therapy in standard-of-care (SOC) practice.Methods Patients who received tarlatamab at Mayo Clinic Rochester consented to research blood. Immune phenotyping was performed on whole blood by flow cytometry and analyzed by Kaluza. Data analysis was performed with Excel and PRISM.Results Thirteen patients with a median age 64 years (range 41-80) who were treated and evaluable for clinical response were included, 53% were women. All had a history of tobacco use.Nine (69%) patients had progressive disease (PD) after a median of 2 cycles, whereas 4 patients had partial response (PR) or stable disease (SD) after at least 2 cycles and remain on therapy (no-PD). Compared to the no-PD group, those whose disease PD early had higher levels of exhausted CD8 T cells at baseline (PD1+TIGIT+CD57+, PD vs no-PD, cells/µL: 17.4±5.6, 7.6±2.6, p=0.006). Interestingly, a CD8 TIGIT+PD1negCD57neg population was also identified which was higher at baseline (PD vs no-PD, cells/µL: 21.5±16.9, 12.2±5.33, p=0.039) and decreased significantly for the PD group from baseline to day 7 (21.5±16.9 to 9.30±10, p=0.039; figure 1A). This population was found to have a different functional profile than the exhausted phenotype in other solid tumors and its role in small cell lung cancer has not been defined. At day 7, compared to the no-PD group, the PD group also had a high level of B-cells (PD vs no-PD, cells/µL: 10.3±15, 4.07±1.83, p=0.027), classical monocytes (PD vs no-PD, cells/µL: 365±279, 226±121, p=0.035), and immunosuppressive monocytes (CD14+HLA-DRneg monocytes, cells/µL: 119±93, 33±42, p=0.05). In addition, the no-PD group had a statistically significant decrease from baseline to day 7 in intermediate monocytes (32.5±7.9 to 17±2.6, p=0.049; figure 1B).Conclusions In this study investigating the SOC outcomes of tarlatamab, early PD was associated with higher presence of exhausted CD8 T cells, B cells, and immunosuppressive monocytes. Analysis of additional patients will be shared at SITC meeting.Abstract 844 Figure 1ACD8 T cell phenotype associated with clinical responseAbstract 844 Figure 1BMonocyte phenotype associated with clinical response",
  "authors": [
    {
      "affiliations": [
        "Mayo Clinic, Princeton, NJ, USA"
      ],
      "name": "Audrey Ma"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Andre de Menezes Silva Corraes"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Chen Wu"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Zuoyi Shao"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Kevin Regan"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Dhauna Karam"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Ashley Potter"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Abdullah Al-Ajmi"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Syeda Mina"
    },
    {
      "affiliations": [
        "Mayo Clinic, Scottsdale, AZ, USA"
      ],
      "name": "Skyler J Taylor"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Antonious Hazim"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Anastasios Dimou"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Kaushal Parikh"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Mohamed Shanshal"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Julian Molina"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Aaron Mansfield"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Katherine ER Smith"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Ailsa Luce"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Anna Schwecke"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Yi Lin"
    },
    {
      "affiliations": [
        "Mayo Clinic, Rochester, MN, USA"
      ],
      "name": "Konstantinos Leventakos"
    }
  ],
  "title": "844 Immune cell profile changes in patients treated with tarlatamab for extensive-stage small cell lung cancer in real world practice",
  "uid": "78ae383a-8d72-51ee-b8ed-a8eaf579fbf3"
}