Neoantigens induced by random mutations and specific to an individual's cancer are the most important tumor antigens recognized by T cells. Among immunologically “cold” tumors, limited recognition of tumor neoantigens results in the absence of a de novo antitumor immune response. These “cold” tumors present a clinical challenge as they are poorly responsive to most immunotherapies, including immune checkpoint inhibitors (ICIs). Radiation therapy (RT) can enhance immune recognition of “cold” tumors, resulting in a more diversified antitumor T‐cell response, yet RT alone rarely results in a systemic antitumor immune response. Therefore, a multifunctional bacterial membrane‐coated nanoparticle (BNP) composed of an immune activating PC7A/CpG polyplex core coated with bacterial membrane and imide groups to enhance antigen retrieval is developed. This BNP can capture cancer neoantigens following RT, enhance their uptake in dendritic cells (DCs), and facilitate their cross presentation to stimulate an antitumor T‐cell response. In mice bearing syngeneic melanoma or neuroblastoma, treatment with BNP+RT results in activation of DCs and effector T cells, marked tumor regression, and tumor‐specific antitumor immune memory. This BNP facilitates in situ immune recognition of a radiated tumor, enabling a novel personalized approach to cancer immunotherapy using off‐the‐shelf therapeutics.

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IntroductionCombining CpG oligodeoxynucleotides with anti-OX40 agonist antibody (CpG+OX40) is able to generate an effective in situ vaccine in some tumor models, including the A20 lymphoma model. Immunologically “cold” tumors, which are typically less responsive to immunotherapy, are characterized by few tumor infiltrating lymphocytes (TILs), low mutation burden, and limited neoantigen expression. Radiation therapy (RT) can change the tumor microenvironment (TME) of an immunologically “cold” tumor. This study investigated the effect of combining RT with the in situ vaccine CpG+OX40 in immunologically “cold” tumor models.MethodsMice bearing flank tumors (A20 lymphoma, B78 melanoma or 4T1 breast cancer) were treated with combinations of local RT, CpG, and/or OX40, and response to treatment was monitored. Flow cytometry and quantitative polymerase chain reaction (qPCR) experiments were conducted to study differences in the TME, secondary lymphoid organs, and immune activation after treatment.ResultsAn in situ vaccine regimen of CpG+OX40, which was effective in the A20 model, did not significantly improve tumor response or survival in the “cold” B78 and 4T1 models, as tested here. In both models, treatment with RT prior to CpG+OX40 enabled a local response to this in situ vaccine, significantly improving the anti-tumor response and survival compared to RT alone or CpG+OX40 alone. RT increased OX40 expression on tumor infiltrating CD4+ non-regulatory T cells. RT+CpG+OX40 increased the ratio of tumor-infiltrating effector T cells to T regulatory cells and significantly increased CD4+ and CD8+ T cell activation in the tumor draining lymph node (TDLN) and spleen.ConclusionRT significantly improves the local anti-tumor effect of the in situ vaccine CpG+OX40 in immunologically “cold”, solid, murine tumor models where RT or CpG+OX40 alone fail to stimulate tumor regression.

Overall survival (OS) was calculated from the date of diagnosis until the date of death or last follow up. Kaplan-Meier analysis was performed for determining overall survival (OS). IBM software was used for statistical analysis; p-value < 0.05 was considered statistically significant. Results: Of the 38,494 patients, the median age of the patients was 75 years (range: 26-90); 47.2% male, 89.6% white, 8.3% black. The median follow-up was 25.9 months. During 2004-2015 about 30.6% (nZ11,763) patients were treated with SF-EBRT while 69.4% (nZ26,731) patients were treated with the SBRT. There was a clear trend of increasing use of SBRT in more recent years (<1,000 in 2006 vs >9,500 in 2015). The mean and median OS of the patients treated with SBRT were significantly higher (about 11months higher; Table 1) as compared to the patients in SF-EBRT group. One-year, three-year and five-year OS are also significantly better in SBRT group. Conclusion: This study indicates that for early stage inoperable NSCLC, SBRT is the preferred method of treatment. SBRT provides significantly improved overall survival over SF-EBRT. Therefore, every effort should be made to treat the eligible early stage NSCLC patients with SBRT. Further analysis using multivariable risk model is underway.

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.