Author Manuscript Published OnlineFirst on February 18, 2020; DOI: 10.1158/1078-0432.CCR-19-3642 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 1 Intratumoral immunotherapy for early-stage solid tumors 2 3 Wan Xing Hong1,2*, Sarah Haebe2,3*, Andrew S. Lee4,5, C. Benedikt Westphalen3,6,7, 4 Jeffrey A. Norton1,2, Wen Jiang8, Ronald Levy2# 5 6 1. Department of Surgery, Stanford University School of Medicine 7 2. Stanford Cancer Institute, Division of Oncology, Department of Medicine, Stanford University 8 3. Department of Medicine III, University Hospital, LMU Munich, Germany 9 4. Department of Pathology, Stanford University School of Medicine 10 5. Shenzhen Bay Labs, Cancer Research Institute, Shenzhen, China 11 6. Comprehensive Cancer Center Munich, Munich, Germany 12 7. Deutsches Konsortium für Translationale Krebsforschung (DKTK), DKTK Partner Site Munich, 13 Germany 14 8. Department of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, 15 Texas, USA 16 * These authors contributed equally to this work 17 # Correspondence: [email protected]. 18 CCSR 1105, Stanford, California 94305-5151 19 (650) 725-6452 (office) 20 21 Running title: Intratumoral immunotherapy for early-stage solid tumors 22 23 24 Conflict of Interest 25 Dr. Ronald Levy serves on the advisory boards for Five Prime, Corvus, Quadriga, BeiGene, GigaGen, 26 Teneobio, Sutro, Checkmate, Nurix, Dragonfly, Abpro, Apexigen, Spotlight, 47 Inc, XCella, 27 Immunocore, Walking Fish. 28 Dr. Benedikt Westphalen is on the advisory boards for Celgene, Shire/Baxalta Rafael Pharmaceuticals, 29 Redhill and Roche. He receives research support from Roche. 30 The other authors report no conflicts of interest. 31 32 Key words: cancer immunotherapy, intratumoral therapy, neoadjuvant, combination immunotherapy 33 34 Abstract 35 The unprecedented benefits of immunotherapy in advanced malignancies have resulted in increased 36 interests in exploiting immune stimulatory agents in earlier stage solid tumors in the neoadjuvant setting. 37 However, systemic delivery of immunotherapies may cause severe immune-related side-effects and 38 hamper the development of combination treatments. Intratumoral delivery of neoadjuvant immunotherapy 39 provides a promising strategy in harnessing the power of immunotherapy while minimizing off-target 40 toxicities. The direct injection of immune stimulating agents into the tumor primes the local tumor- 41 specific immunity to generate a systemic, durable clinical response. Intratumoral immunotherapy is a 42 highly active area of investigation resulting in a plethora of agents, e.g. immune receptor agonists, non- 43 oncolytic and oncolytic viral therapies, being tested in preclinical and clinical settings. Currently, more 44 than 20 neoadjuvant clinical trials exploring distinct intratumoral immune stimulatory agents and their 45 combinations are ongoing. Practical considerations including appropriate timing and optimal local 46 delivery of immune stimulatory agents play an important role in safety and efficacy of this approach. 47 Here we discuss promising approaches in drug delivery technologies and opportunity for combining 48 intratumoral immunotherapy with other cancer treatments and summarize the recent preclinical and 49 clinical evidences that highlighted its promise as a part of routine oncologic care. 50 51 1 Downloaded from clincancerres.aacrjournals.org on September 27, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on February 18, 2020; DOI: 10.1158/1078-0432.CCR-19-3642 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 52 Introduction 53 Significant advances in the field of immunotherapy over the past decade have provided an 54 alternative to conventional treatments, which in many advanced solid tumors involve chemotherapy 55 and/or radiation, and associated toxicities. Strong clinical benefits of immunotherapy have been observed 56 for patients receiving immunotherapy in second line therapy or even in the adjuvant setting (defined as 57 treatment after primary surgical resection or radiation)(1–3). This has generated interest in the adoption of 58 cancer immunotherapies prior to local treatments as a neoadjuvant modality (4). Intratumoral 59 immunotherapy, the direct inoculation of immune stimulating agents into the tumor itself, has a number 60 of features that make it particularly useful in the neoadjuvant setting. In this approach immune stimulating 61 agents are injected directly into the tumor site, thus avoiding off-target toxicities and adverse effects that 62 can accompany global immune stimulation. Whereas toxicity of systemic immunotherapy has been shown 63 to be dose related(5), local delivery of a high concentration immunotherapy agent generally translates to 64 overall lower systemic dosages and lower systemic exposure due to limited diffusion of the agent(6). In 65 addition, when compared to systemic administration, local administration requires a much lower dose of 66 the agents to induce a local and systemic antitumor response. Intratumoral delivery can thus avoid 67 problems with dose-limiting toxicity or allow for the use of combinations of agents that have poor 68 systemic safety profiles(6). 69 Furthermore, direct injection at the tumor site ensures access to tumor infiltrating T cells already 70 in the tumor microenvironment and potentially enriched for tumor antigen recognition. Recent studies 71 have noted intratumor differences in T cell density and clonality, possibly due to differences in 72 neoantigens in different tumor regions(7). As a result, local immunotherapy may elicit an immune 73 response where systemic administration of immunotherapy is not efficacious by leveraging the rich pool 74 of antigens within the tumor to provide better priming of polyclonal antitumor response(8). 75 In this review, we will address practical considerations for intratumoral immunotherapy and 76 summarize recent preclinical and clinical studies utilizing neoadjuvant intratumoral immunotherapy. 77 Finally, we will synthesize findings from clinical literature to provide suggestions for combining cancer 78 surgery with intratumoral therapy to improve outcomes for patients with resectable solid tumors that have 79 a high risk of distant recurrence. 80 81 Considerations for clinical utilization 82 The goal of intratumoral immunotherapy is to prime immune cells locally to generate a systemic 83 antitumor effect. By using the tumor as its own vaccine, this approach allows for the generation of 84 antitumor immunity against multiple cancer cell antigens without having to pre-identify those antigens. 85 As such, intratumoral immunotherapy can potentially elicit a polyclonal antitumor immune response 86 against multiple concurrent targets and provide a broad attack against tumor heterogeneity (Figure 1). 87 Furthermore, intratumoral injections allow for the delivery of high concentrations of drugs at the 88 tumor site while keeping total dose and systemic drug exposure low. However, there are several clinical 89 factors that must be taken into consideration when using local immunotherapy. These include timing and 90 scheduling of therapy, choice of agents utilized, and opportunity for combination with other therapies. 91 92 Timing of therapy: earlier the better? 93 Traditional chemotherapeutic or radiation therapy prior to surgery, termed neoadjuvant therapy, 94 has demonstrated improved patient outcomes across a spectrum of solid tumors(9–11). The potential of 95 neoadjuvant immunotherapy however remains under clinical evaluation and its utility in this setting is 96 unclear (Figure 2). 97 Several groups have postulated that early immunotherapy in the neoadjuvant setting can 98 potentially improve treatment options for a large number of patients with resectable solid 99 tumors(4,12,13). There are several mechanisms by which this would be possible. First, upfront treatment 100 can cause a local therapeutic effect to reduce primary tumor burden, minimizing the extent and morbidity 101 of surgery. For some patients with locally advanced and borderline resectable tumors, neoadjuvant 102 immunotherapy can shrink the primary tumor and even make an unresectable tumor resectable. Second, 2 Downloaded from clincancerres.aacrjournals.org on September 27, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on February 18, 2020; DOI: 10.1158/1078-0432.CCR-19-3642 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. 103 earlier treatment can reduce recurrence in patients by targeting systemic micro-metastatic disease at time 104 of resection. Third, upfront immunotherapy allows for faster determination of initial therapeutic success 105 through the evaluation of the resected tumor specimen to determine efficacy of treatment on primary 106 tumor tissue and guide subsequent clinical decision-making. Lastly, neoadjuvant immunotherapy 107 capitalizes on the presence of primary tumor as a rich source of antigens for T cell priming(14,15). The 108 intact tumor can thereby act as an “in situ” vaccine, thereby inducing a broader and more potent anti- 109 tumor immune response. This particular benefit can be magnified through the use of intratumoral immune 110 stimulation to target tumor infiltrating lymphocytes. Therefore, by creating an earlier therapeutic window, 111 decreasing risk