Brian T. Craig

Surgery for local control is a cornerstone of anticancer therapy with demonstrated survival benefit. However, surgery-induced modulation of antitumor immunity may also contribute to cancer progression and relapse. Despite evidence for a pro-tumor surgery effect in adult cancers, there remain significant knowledge gaps as to the influence surgery has on recurrence or metastatic outgrowth in pediatric cancers. High-risk neuroblastoma (HR-NB) is the most common extracranial solid tumor of childhood. While almost all children with HR-NB undergo surgery, nearly 50% suffer metastatic relapse and succumb to their disease. To ascertain if surgery may contribute to recurrence in HR-NB, we developed a mouse model to comprehensively interrogate the systemic effect of surgery on distant tumor growth and immune modulation. This model demonstrated that MYCN-amplified HR-NB tumor growth was accelerated by surgery compared to tumor-bearing mice without surgical stress. Accelerated tumor growth was absent in HR-NB cells engrafted to immune deficient mice, suggesting that an intact immune system may be needed for surgery to exert its pro-growth effect on distant tumor cells. Consistent with that genetic ablation model, flow cytometry measured a decrease in splenic macrophages (Mϕ) and dendritic cells (DC) and an increase in myeloid-derived suppressor cells (MDSC) after surgery. Perioperative treatment with polyinosinic-polycytidylic acid [poly(I:C)] ameliorated surgery-induced tumor growth. These findings provide direct insight into the systemic surgical effect on pediatric solid tumor growth and identify innate immune adjuvants as a potential perioperative treatment to mitigate this effect.

Neuroblastoma (NBL) cells highly express disialoganglioside GD2, which is restricted and weakly expressed in selected healthy cells, making it a desirable target of immunotherapy. Over the past two decades, application of dinutuximab, an anti-GD2 monoclonal antibody (mAb), has been one of the few new therapies to substantially improve outcomes to current levels. Given the persistent challenge of relapse and therapeutic resistance, there is an urgent need for new effective and tolerable treatment options for high-risk NBL. Recent breakthroughs in immune checkpoint inhibitor (ICI) therapeutics have not translated into high-risk NBL, like many other major pediatric solid tumors. Given the suppressed tumor microenvironment (TME), single ICIs like anti-CTLA4 and anti-PD1 have not demonstrated significant antitumor response rates. Meanwhile, emerging studies are reporting novel advancements in GD2-based therapies, targeted therapies, nanomedicines, and other immunotherapies such as adoptive transfer of natural killer (NK) cells and chimeric antigen receptors (CARs), and these hold interesting promise for the future of high-risk NBL patient care. Herein, we summarize the current state of the art in NBL therapeutic options and highlight the unique challenges posed by NBL that have limited the successful adoption of immune-modifying therapies. Through this review, we aim to direct the field’s attention to opportunities that may benefit from a combination immunotherapy strategy.

Surgery or radiation therapy is nearly universally applied for pediatric solid tumors. In many cases, in diverse tumor types, distant metastatic disease is present and evades surgery or radiation. The systemic host response to these local control modalities may lead to a suppression of antitumor immunity, with potential negative impact on the clinical outcomes for patients in this scenario. Emerging evidence suggests that the perioperative immune responses to surgery or radiation can be modulated therapeutically to preserve anti-tumor immunity, with the added benefit of preventing these local control approaches from serving as pro-tumorigenic stimuli. To realize the potential benefit of therapeutic modulation of the systemic response to surgery or radiation on distant disease that evades these modalities, a detailed knowledge of the tumor-specific immunology as well as the immune responses to surgery and radiation is imperative. In this Review we highlight the current understanding of the tumor immune microenvironment for the most common peripheral pediatric solid tumors, the immune responses to surgery and radiation, and current evidence that supports the potential use of immune activating agents in the perioperative window. Finally, we define existing knowledge gaps that limit the current translational potential of modulating perioperative immunity to achieve effective anti-tumor outcomes.