Abstract 4455: Combination of bempegaldesleukin and anti-CTLA-4 prevents metastatic dissemination after primary surgery or radiation therapy in a preclinical model of non-small cell lung cancer
Authors: Brown Ryan J. , Zangl Luke , Arthur Ian , Pieper Alex , Carlson Peter M. , Castillo Juliana , Sondel Paul M. , Rakhmilevich Alexander , Morris Zach S. , Patel Ravi B. 
Published: September 2020

Abstract
Purpose: Surgical resection or stereotactic ablative radiation therapy (SBRT) in early stage non-small cell lung cancer (NSCLC) have local control rates of 90% or higher. Current treatment paradigms effectively control primary tumor sites, but distant relapse remains a challenge with metastatic failure in more than 30% of patients with primary tumors larger than 5 cm. We hypothesized that adjuvant immune checkpoint blockade with anti-CTLA4 (C4) and /or bempegaldesleukin (NKTR-214), a CD122-preferential pegylated-interleukin-2 (IL2) pathway agonist,in combination with primary tumor ablative radiation or surgical resection would reduce metastases in a spontaneously metastatic syngeneic Lewis Lung Carcinoma (LLC) model.
Methods: LLC flank tumors were established in C57BL/6 mice (n=6 per replicate, 12 total). When tumors were ~100 mm3 they were randomized to receive: vehicle only (VO); NKTR-214 (16 μg on Days 6, 15, 24) + C4 (200 μg IP on Days 4, 7, 10); RT (8Gy x 3 on Days 1, 2, 3); RT + C4, RT + NKTR-214; RT + C4 + NKTR-214; Primary surgery (Day 16), or Surgery + NKTR-214 + C4. Primary tumor size, survival, and a binary assessment of metastatic disease was made for each mouse. Flow cytometry studies examined tumor immune cell infiltrates on Day 21 in mice treated with VO, RT, RT + C4, C4 + NKTR-214, or RT + C4 + NKTR-214.
Results: NKTR + C4 prevented development of spontaneous metastasis (p &lt; 0.01) but did not control primary disease compared to VO treatment. RT alone significantly reduced primary tumor size compared to VO control (p &lt; 0.01), but these mice all developed metastases. Adjuvant NKTR-214 + C4 after RT reduced development of spontaneous metastasis in mice treated by this regimen by 91% and 73% compared to RT alone and RT + C4 respectively. RT + C4 + NKTR-214 also significantly improved survival compared to both RT + C4 and RT + NKTR-214 (p = 0.02, p = 0.003). 58% of mice treated with RT + C4 + NKTR-214 cleared their primary tumors compared to 16% with RT + C4 and 0% in RT + NKTR-214 at day 30 (p = 0.03, p &lt; 0.01). All mice clearing primary tumors rejected LCC rechallenge. Flow cytometric immuneprofiling of the primary tumors demonstrated increased CD8+T cells, NK cells (NK1.1+CD3−), and NKT cells (NK1.1+CD3+) with NKTR-214 + C4 w/wo RT treatment compared to VO controls. NKTR-214 + C4 prior to surgical resection also reduced the development of spontaneous lung metastases compared to surgery alone (p &lt; 0.01).
Conclusions: Addition of systemic NKTR-214 + C4 treatment to RT or primary surgical resection reduces development of distant metastatic disease in a preclinical NSCLC model. Moreover, treatment with NKTR-214 + C4 increases infiltration of innate and adaptive immune effector cells in the primary tumor. This treatment strategy has important translational potential to prevent distant relapse in patients undergoing definitive local therapies for early stage NSCLC.
Citation Format: Ryan J. Brown, Luke Zangl, Ian Arthur, Alex Pieper, Peter M. Carlson, Juliana Castillo, Paul M. Sondel, Alexander Rakhmilevich, Zach S. Morris, Ravi B. Patel. Combination of bempegaldesleukin and anti-CTLA-4 prevents metastatic dissemination after primary surgery or radiation therapy in a preclinical model of non-small cell lung cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4455.