Sentinel lymph node biopsy in head and neck rhabdomyosarcoma.

Head and neck rhabdomyosarcoma lymph node staging is challenging due to varied patterns of lymphatic drainage and the suboptimal predictive value of available imaging modalities. Furthermore, regional relapse rates are unacceptably high, and the toxicity of empiric radiation is undesirable in the pediatric and young adult population. In an attempt to improve locoregional control without excess morbidity, we have adopted routine sentinel lymph node biopsy in head and neck rhabdomyosarcoma, which is safe and feasible in pediatric patients. Of six procedures reported here, pathologic findings led to intensification of regional and/or systemic therapy in two patients.

Harnessing the cGAS-STING pathway to potentiate radiation therapy: current approaches and future directions.

In this review, we cover the current understanding of how radiation therapy, which uses ionizing radiation to kill cancer cells, mediates an anti-tumor immune response through the cGAS-STING pathway, and how STING agonists might potentiate this. We examine how cGAS-STING signaling mediates the release of inflammatory cytokines in response to nuclear and mitochondrial DNA entering the cytoplasm. The significance of this in the context of cancer is explored, such as in response to cell-damaging therapies and genomic instability. The contribution of the immune and non-immune cells in the tumor microenvironment is considered. This review also discusses the burgeoning understanding of STING signaling that is independent of inflammatory cytokine release and the various mechanisms by which cancer cells can evade STING signaling. We review the available data on how ionizing radiation stimulates cGAS-STING signaling as well as how STING agonists may potentiate the anti-tumor immune response induced by ionizing radiation. There is also discussion of how novel radiation modalities may affect cGAS-STING signaling. We conclude with a discussion of ongoing and planned clinical trials combining radiation therapy with STING agonists, and provide insights to consider when planning future clinical trials combining these treatments.

The tailless complex polypeptide-1 ring complex of the heat shock protein 60 family facilitates cross-priming of CD8 responses specific for chaperoned peptides.

The tailless complex polypeptide-1 ring complex (TRiC) is a eukaryotic heat shock protein 60 (hsp60) molecule that has been shown to bind N-terminally extended precursors of OVA-derived SIINFEKL in vivo. Binding of peptides to TRiC was shown to be essential for their presentation on MHC class I. We demonstrate in this study that purified TRiC binds antigenic peptides in vitro as well; however, such binding is not restricted to N-terminally extended peptides, suggesting that the results obtained in vivo reflect the availability of peptides in vivo rather than structural constraints of TRiC-peptide binding. Immunization of mice with noncovalent complexes of peptides (derived from OVA or ß-galactosidase) and TRiC results in cross-priming of CD8(+) T lymphocytes specific for K(b)/SIINFEKL or L(d)/TPHPARIGL. Mechanistic dissection of this phenomenon shows that TRiC binds APC, and TRiC-chaperoned peptides are processed within the APC and presented on their MHC class I. Immunogenicity of TRiC purified from OVA- or ß-galactosidase-expressing cells, that is, of endogenously generated TRiC-peptide complexes, was investigated, and such preparations were observed not to be immunogenic. Consistent with this observation, SIINFEKL or its precursors were not observed to be associated with TRiC purified from cells expressing a fusion GFP-OVA protein. In contrast, immunization with TRiC purified from a tumor elicited specific protection against a challenge with that tumor. These results are interpreted with respect to the cell biological properties of TRiC and suggest that in vivo, TRiC binds a limited proportion of peptides derived from a limited set of intracellular proteins.

Extraneural recurrence of an intracranial nongerminomatous germ cell tumor to cervical lymph nodes in a pediatric patient: Case report.

BACKGROUND: Intracranial germ cell tumors (GCTs) comprise 3%-5% of pediatric primary central nervous system (CNS) tumors in Western countries. Though they are related in embryonic origin to gonadal GCTs, which are considered highly treatable with cisplatin-based chemotherapy regimens, intracranial GCTs vary in malignant potential and sensitivity to radiation and chemotherapy, generally carrying a worse prognosis. Metastases of intracranial GCTs outside of the CNS are rare, indicate a poor prognosis, and their salvage treatment is not well established. CASE: A 15-year-old boy presented with bifocal (suprasellar and pineal) intracranial nongerminomatous germ cell tumors of mixed origin. The tumors were treated to full response with a multimodal approach of neoadjuvant chemotherapy, surgical resection, and adjuvant craniospinal proton radiation. Nine months following treatment completion, the patient presented with an enlarged cervical lymph node determined on excisional biopsy to be a recurrence of pure germinoma from the primary tumors. Salvage treatment involved high-dose chemotherapy and autologous stem cell transplantation; however, the patient denied further treatment prior to planned focal radiotherapy. Thirty months post-treatment, the patient is well with no evidence of recurrence. CONCLUSION: This case demonstrated the successful salvage treatment of an extraneural recurrence of an intracranial GCT using surgical resection and a high-dose chemotherapy and autologous stem-cell transplantation regimen, highlighting the unique factors which led to the selection of this regimen.

Cognitive and behavioral effects of whole brain conventional or high dose rate (FLASH) proton irradiation in a neonatal Sprague Dawley rat model.

Recent studies suggest that ultra-high dose rates of proton radiation (>40 Gy/s; FLASH) confer less toxicity to exposed healthy tissue and reduce cognitive decline compared with conventional radiation dose rates (~1 Gy/s), but further preclinical data are required to demonstrate this sparing effect. In this study, postnatal day 11 (P11) rats were treated with whole brain irradiation with protons at a total dose of 0, 5, or 8 Gy, comparing a conventional dose rate of 1 Gy/s vs. a FLASH dose rate of 100 Gy/s. Beginning on P64, rats were tested for locomotor activity, acoustic and tactile startle responses (ASR, TSR) with or without prepulses, novel object recognition (NOR; 4-object version), striatal dependent egocentric learning ([configuration A] Cincinnati water maze (CWM-A)), prefrontal dependent working memory (radial water maze (RWM)), hippocampal dependent spatial learning (Morris water maze (MWM)), amygdala dependent conditioned freezing, and the mirror image CWM [configuration B (CWM-B)]. All groups had deficits in the CWM-A procedure. Weight reductions, decreased center ambulation in the open-field, increased latency on day-1 of RWM, and deficits in CWM-B were observed in all irradiated groups, except the 5 Gy FLASH group. ASR and TSR were reduced in the 8 Gy FLASH group and day-2 latencies in the RWM were increased in the FLASH groups compared with controls. There were no effects on prepulse trials of ASR or TSR, NOR, MWM, or conditioned freezing. The results suggest striatal and prefrontal cortex are sensitive regions at P11 to proton irradiation, with reduced toxicity from FLASH at 5 Gy.

Whole brain proton irradiation in adult Sprague Dawley rats produces dose dependent and non-dependent cognitive, behavioral, and dopaminergic effects.

Proton radiotherapy causes less off-target effects than X-rays but is not without effect. To reduce adverse effects of proton radiotherapy, a model of cognitive deficits from conventional proton exposure is needed. We developed a model emphasizing multiple cognitive outcomes. Adult male rats (10/group) received a single dose of 0, 11, 14, 17, or 20 Gy irradiation (the 20 Gy group was not used because 50% died). Rats were tested once/week for 5 weeks post-irradiation for activity, coordination, and startle. Cognitive assessment began 6-weeks post-irradiation with novel object recognition (NOR), egocentric learning, allocentric learning, reference memory, and proximal cue learning. Proton exposure had the largest effect on activity and prepulse inhibition of startle 1-week post-irradiation that dissipated each week. 6-weeks post-irradiation, there were no effects on NOR, however proton exposure impaired egocentric (Cincinnati water maze) and allocentric learning and caused reference memory deficits (Morris water maze), but did not affect proximal cue learning or swimming performance. Proton groups also had reduced striatal levels of the dopamine transporter, tyrosine hydroxylase, and the dopamine receptor D1, effects consistent with egocentric learning deficits. This new model will facilitate investigations of different proton dose rates and drugs to ameliorate the cognitive sequelae of proton radiotherapy.

STING, DCs and the link between innate and adaptive tumor immunity.

Cancer and the immune system are intimately related. Much of the bulk of tumors is comprised of stromal leukocytes with immune functions, which serve to both promote and inhibit tumor growth, invasion and metastasis. The T lymphocytes of the adaptive immune system are essential for tumor immunity, and these T cells are generated by cross-priming against tumor associated antigens. Dendritic cells (DCs) are essential in this process, serving as the cellular link between innate and adaptive immunity. As a prerequisite for priming of adaptive immune responses, DCs must take up tumor antigens, process them and present them in the context of the major histocompatibility complex (MHC). DCs also serve as sensors of innate activation signals from cancer that are necessary for their activation and effective priming of cancer specific T cells. Here we discuss the role of DCs in the sensing of cancer and in priming the adaptive response against tumors. Furthermore, we present the essential role of the Stimulator of Interferon Genes (STING) signaling pathway in producing type I interferons (IFNs) that are essential in this process.

Practice Patterns Among Radiation Oncologists Treating Pediatric Patients With Proton Craniospinal Irradiation.

PURPOSE: Craniospinal irradiation (CSI) is an important component of therapy for many pediatric central nervous system malignancies. Proton therapy is increasingly available and used for minimizing radiation exposure to normal tissues. The absence of an exit dose with proton therapy mandates decisions regarding coverage of the vertebral bodies (VB) in non-skeletally mature patients. Although the contents within the thecal sac represent the true clinical target volume (CTV), some physicians target the entire VB in growing children because of concerns over asymmetrical growth. This study aims to assess current practice patterns regarding VB coverage for pediatric patients undergoing CSI. METHODS AND MATERIALS: Pediatric radiation oncologists were identified from the Particle Therapy Co-Operative Group pediatric subcommittee membership or affiliation with US proton centers. Potential participants were contacted by e-mail with a link to an institutional review board-approved, anonymized web-based survey distributed in June 2017 with follow-up in October 2017. The survey used skip logic and included up to 11 questions regarding practice patterns. RESULTS: Thirty-three physicians responded to the survey (39%), 5 of which were excluded for lack of recent pediatric proton CSI experience. Of the 28 included responses, 23 physicians sometimes treat the entire VB and 5 physicians report always treating the entire VB. Most common responses regarding anterior CTV expansion for uncertainty were no expansion (n = 9) and 3 to 4 mm (n = 8). Most physicians modify the anterior CTV margin to protect normal structures, most commonly esophagus (n = 15), thyroid (n = 6), heart (n = 5), bowel (n = 4), and pharynx (n = 2). CONCLUSIONS: Vertebral body coverage in proton CSI varies among radiation oncologists in respect to target delineation, CTV expansions, and modifications for organs at risk. These data suggest the radiation oncology community may benefit from a standardized approach to pediatric proton-based CSI.

Cancer Cell Metabolism: Implications for X-ray and Particle Radiation Therapy.

Advances in radiation delivery technologies and immunotherapy have improved effective cancer treatments and long-term outcomes. Experimental and clinical trials have demonstrated the benefit of a combination of radiation therapy and immunotherapy for tumor eradication. Despite precise radiation dose delivery that is achievable by particle therapy and benefits from reactivating the antitumor immune response, resistance to both therapeutic strategies is frequently observed in patients. Understanding the biological origins of such resistance will create new opportunities for improved cancer treatment. Cancer metabolism and especially a high rate of aerobic glycolysis leading to overproduction and release of lactate is one such biological process favoring tumor progression and treatment resistance. Because of their known protumor effects, aerobic glycolysis and lactate production are potential targets for increased efficacy of radiation alone or in combination with immunotherapy. In the following review, we present an overview of the interplay of cancer cell lactate metabolism with the tumor microenvironment and immune cells. We discuss how a deeper understanding and careful modulation of lactate metabolism and radiation therapy might exploit this interplay for improved therapeutic outcome.

Endocrine Deficiency As a Function of Radiation Dose to the Hypothalamus and Pituitary in Pediatric and Young Adult Patients With Brain Tumors.

PURPOSE: There are sparse data defining the dose response of radiation therapy (RT) to the hypothalamus and pituitary in pediatric and young adult patients with brain tumors. We examined the correlation between RT dose to these structures and development of endocrine dysfunction in this population. MATERIALS AND METHODS: Dosimetric and clinical data were collected from children and young adults (< 26 years of age) with brain tumors treated with proton RT on three prospective studies (2003 to 2016). Deficiencies of growth hormone (GH), thyroid hormone, adrenocorticotropic hormone, and gonadotropins were determined clinically and serologically. Incidence of deficiency was estimated using the Kaplan-Meier method. Multivariate models were constructed accounting for radiation dose and age. RESULTS: Of 222 patients in the study, 189 were evaluable by actuarial analysis, with a median follow-up of 4.4 years (range, 0.1 to 13.3 years), with 31 patients (14%) excluded from actuarial analysis for having baseline hormone deficiency and two patients (0.9%) because of lack of follow-up. One hundred thirty patients (68.8%) with medulloblastoma were treated with craniospinal irradiation (CSI) and boost; most of the remaining patients (n = 56) received involved field RT, most commonly for ependymoma (13.8%; n = 26) and low-grade glioma (7.4%; n = 14). The 4-year actuarial rate of any hormone deficiency, growth hormone, thyroid hormone, adrenocorticotropic hormone, and gonadotropin deficiencies were 48.8%, 37.4%, 20.5%, 6.9%, and 4.1%, respectively. Age at start of RT, time interval since treatment, and median dose to the combined hypothalamus and pituitary were correlated with increased incidence of deficiency. CONCLUSION: Median hypothalamic and pituitary radiation dose, younger age, and longer follow-up time were associated with increased rates of endocrinopathy in children and young adults treated with radiotherapy for brain tumors.

Myeloid-derived cells in tumors: effects of radiation.

The discrepancy between the in vitro and in vivo response to radiation is readily explained by the fact that tumors do not exist independently of the host organism; cancer cells grow in the context of a complex microenvironment composed of stromal cells, vasculature, and elements of the immune system. As the antitumor effect of radiotherapy depends in part on the immune system, and myeloid-derived cells in the tumor microenvironment modulate the immune response to tumors, it follows that understanding the effect of radiation on myeloid cells in the tumor is likely to be essential for comprehending the antitumor effects of radiotherapy. In this review, we describe the phenotype and function of these myeloid-derived cells, and stress the complexity of studying this important cell compartment owing to its intrinsic plasticity. With regard to the response to radiation of myeloid cells in the tumor, evidence has emerged demonstrating that it is both model and dose dependent. Deciphering the effects of myeloid-derived cells in tumors, particularly in irradiated tumors, is key for attempting to pharmacologically modulate their actions in the clinic as part of cancer therapy.

Resection Followed by Involved-Field Fractionated Radiotherapy in the Management of Single Brain Metastasis.

INTRODUCTION: We expanded upon our previous experience using involved-field fractionated radiotherapy (IFRT) as an alternative to whole brain radiotherapy or stereotactic radiosurgery for patients with surgically resected brain metastases (BM). MATERIALS AND METHODS: All patients with single BM who underwent surgical resection followed by IFRT at our institution from 2006 to 2013 were evaluated. Local recurrence (LR)-free survival, distant failure (DF)-free survival, and overall survival (OS) were determined. Analyses were performed associating clinical variables with LR and DF. Salvage approaches and toxicity of treatment for each patient were also assessed. RESULTS: Median follow-up was 19.1 months. Fifty-six patients were treated with a median dose of 40.05 Gy/15 fractions with IFRT to the resection cavity. LR-free survival was 91.4%, DF-free survival was 68.4%, and OS was 77.7% at 12 months. No variables were associated with increased LR; however, melanoma histopathology and infratentorial location were associated with DF on multivariate analysis. LRs were salvaged in 5/8 patients, and DFs were salvaged in 24/29 patients. Two patients developed radionecrosis. CONCLUSION: Adjuvant IFRT is feasible and safe for well-selected patients with surgically resected single BM. Acceptable rates of local control and salvage of distal intracranial recurrences continue to be achieved with continued follow-up.

Combinations of immunotherapy and radiation in cancer therapy.

The immune system has the ability to recognize and specifically reject tumors, and tumors only become clinically apparent once they have evaded immune destruction by creating an immunosuppressive tumor microenvironment. Radiotherapy (RT) can cause immunogenic tumor cell death resulting in cross-priming of tumor-specific T-cells, acting as an in situ tumor vaccine; however, RT alone rarely induces effective anti-tumor immunity resulting in systemic tumor rejection. Immunotherapy can complement RT to help overcome tumor-induced immune suppression, as demonstrated in pre-clinical tumor models. Here, we provide the rationale for combinations of different immunotherapies and RT, and review the pre-clinical and emerging clinical evidence for these combinations in the treatment of cancer.

Specific immunogenicity of heat shock protein gp96 derives from chaperoned antigenic peptides and not from contaminating proteins.

The peptide-binding property of MHC is central to adaptive immunological functions. A similar property of heat shock proteins (HSPs) hsp70 and hsp90 has been implicated in Ag presentation by MHC and in cross-priming. The peptide-binding pocket of hsp70 has been characterized structurally and functionally and a peptide-binding site in gp96 (of hsp90 family) has been defined. Nonetheless, questions persist whether the specific immunogenicity of HSP preparations derives from the peptides chaperoned by the HSPs or by proteins contaminating the HSP preparations. Because absolute purity of a protein preparation is a metaphysical concept, other approaches are necessary to address the question. In this study, we demonstrate that the specific immunogenicity of gp96 preparations isolated from cells expressing beta-galactosidase derives from the MHC I epitope precursors associated with the gp96 and not from contaminating beta-galactosidase protein nor unassociated fragments derived from it. Although the observations here are limited to a single HSP and antigenic peptides chaperoned by it, they can be extended broadly.