Casey, Dana L.

ABSTRACT Pediatric radiation therapy presents unique challenges compared to adult treatments, including those of immobilization, potential need for sedation, and the critical importance of accurate, reproducible positioning. Additionally, heightened attention to imaging doses is necessary to minimize long‐term toxicity in survivors. Many of these challenges must be addressed during the process of simulation. This report provides guidelines for pediatric radiotherapy simulation from the Children's Oncology Group. These guidelines cover all anatomic sites and include recommendations for photon and proton therapies, as well as specialized procedures such as stereotactic body radiation therapy, brachytherapy, and total body irradiation. These guidelines are presented as recommendations rather than prescriptive standards as the practice will vary depending on patient age, diagnosis, clinical judgment, and institutional resources.

Summary Outcomes for high‐risk paediatric classic Hodgkin lymphoma (cHL) improved with the addition of brentuximab vedotin (Bv) to doxorubicin, vincristine, etoposide, prednisone and cyclophosphamide (AVEPC) chemotherapy. We evaluated the prognostic implications of distant extra‐nodal sites contributing to stage IV disease. On AHOD1331 (NCT02166463), patients aged 2–21 years with high‐risk cHL (stage IIB with bulk/IIIB/IVA/IVB) were randomized to 5 cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone and cyclophosphamide (ABVE‐PC) versus Bv‐AVEPC. Patients with stage IV disease, determined by protocol‐defined and centrally reviewed Positron Emission Tomography ‐ Computed Tomography (PET‐CT), were identified. Baseline characteristics and progression‐free survival (PFS) were compared by pattern of stage IV involvement (lung, bone, bone marrow, multiple sites and others). A total of 340 patients (median age 15 years) with stage IV disease were included. Of these patients, 173 (51%) received ABVE‐PC and 167 (49%) Bv‐AVEPC. PFS was highest with lung‐only involvement (4‐year PFS 88.6%) and lowest with bone marrow‐only involvement (4‐year PFS 71.9%). Compared to ABVE‐PC, Bv‐AVEPC improved PFS among all stage IV patients (hazard ratio [HR] 0.53, 90% confidence interval (CI) 0.33–0.85) and in the lung‐only and bone‐only subgroups. However, no PFS benefit was observed in those with bone marrow‐only involvement. Among paediatric patients with stage IV cHL, Bv‐AVEPC improved PFS across most patterns of stage IV disease, except in those with bone marrow involvement. These results will guide efforts to improve outcomes among children with stage IV cHL.

Abstract Introduction: Hormone receptor positive (HR+), HER2- breast cancer (BC) is the most common subtype of BC. Despite advances in chemotherapy and endocrine therapy optimization, local and systemic recurrences frequently occur, especially for patients with node-positive disease. Recent data suggest a subset of patients with this tumor phenotype may benefit from the addition of anti-Programmed Death-1(aPD1) to neoadjuvant chemotherapy. However, T-cell infiltration (TCI), a biomarker of response to aPD1 and chemotherapy, is typically low in this BC subtype. Preclinical models show that combining preoperative radiation therapy (preop RT) with immune checkpoint inhibitors can enhance TCI and anti-tumor immunity. We conducted the first randomized trial to test whether no-, low- or high-dose RT combined with aPD1 increases TCI and improves responses in non-irradiated, metastatic lymph nodes in HR+/HER2- BC (NCT04443348). Materials & Methods: Eligible patients had ER and/or PR≥10%, HER2 negative invasive BC with clipped and biopsy-proven positive axillary node(s), cT1c-T4c, cN1-3, and at least one of the following criteria: grade 3 or grade 1-2 with cN2-N3, Ki67 >20%, or high genomic assay score. Between 2022-2024, 51 patients from 10 centers were randomized to no (0Gy; control arm), low (9Gy) or high (24Gy) doses of preop RT to the primary tumor with concurrent pembrolizumab followed by a 2-week tumor biopsy. Stratification factors were T1c vs. T2-4 and N1 vs. N2-3. Patients subsequently received pembrolizumab with 12 weeks of paclitaxel, followed by 4 cycles of adriamycin-cyclophosphamide (q2wk or q3wk) with pembrolizumab (200 mg q3 wks or 400 mg q6 wks). Surgery and adjuvant therapy followed standard-of-care. Dual co-primary endpoints were 2wk tumor TCI and nodal pathologic complete response (ypN0) at time of definitive surgery. TCI was assessed by multiplex immunofluorescence (pan-cytokeratin, CD3, CD8), using a rank-based Immunoscore (range 0-1), compared to baseline reference biopsies via two-tailed Mann-Whitney test. ypN0 was evaluated non-comparatively. Secondary endpoints included pCR and Residual Cancer Burden (RCB) 0/1. Results: Among 51 patients enrolled, 49 were evaluable for TCI and 48 for the ypN0 endpoint. Median age was 49.5 years (range 23-78). The cohort had a high-risk clinical profile: 92% had cT2-4, 50% N2-3, and 62% grade 3 tumors. Median ER and PR positivity were 90% (20-100) and 68% (1-98), respectively. Multifocal or multicentric tumors were present in 32%. TCI was assessed at 2 weeks post-treatment. The proportion of tumors with TCI in the upper quartile increased with RT dose escalation: 31% (0Gy), 40% (9Gy), and 53% (24Gy). Median TCI scores at 2 weeks were 0.60 (0Gy), 0.56 (9Gy), and 0.82 (24Gy), compared to a median baseline value of 0.50 from untreated reference samples. A statistically significant increase in TCI was observed only in the 24Gy cohort relative to the untreated group (p=0.027). 70.8% underwent mastectomy, with 39.6% receiving immediate reconstruction. 8% experienced G2/3 wound complications, balanced across arms. Median number of lymph nodes removed was 6.5 (1-42). The overall ypN0 rate was 29%, and 24%(0Gy), 29%(9Gy) and 33%(24Gy) per arm. pCR/RCB 0-1 rates were 18%/27% in the entire cohort and 6%/18%(0Gy), 29%/29%(9Gy), and 19%/33%(24Gy), respectively. Conclusion: The addition of 24Gy preop RT to aPD1 significantly increased tumor TCI in HR+/HER2- early-stage BC. Non-irradiated nodal response rates were promising despite over one-third of the study population with grade 1/2 tumors and high disease burden, laying the foundation for a future randomized trial comparing the efficacy of this novel approach against standard of care for node-positive HR+/HER2- BC. Citation Format: G. Gupta, A. Y. Ho, F. Gharibpoor, Y. Abdou, J. D. Anampa, R. C. Blitzblau, B. C. Calhoun, D. L. Casey, S. F. Dent, L. A. Carey, J. R. Bellon, L. E. Warren, J. Lu, T. J. Hieken, A. G. Taghian, A. Bardia, T. Traina, G. Plitas, K. Gallagher, K. Daugherty, A. Thompson, I. Krop, A. Wolff, E. Mittendorf, J. Fox, H. Garber, E. Hwang, A. J. Khan, J. P. Loene, R. Mutter, S. Patil, C. Santa-Maria, B. V. Vincent, J. L. Wright, L. Spring.Primary Results from the HR+/HER2- Cohort of TBCRC-053 (P-RAD): A Randomized Trial of No, Low, or High Dose Preoperative RADiation with Pembrolizumab and Chemotherapy in Node-Positive, HER2-Negative Breast Cancer [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr GS2-05.

ABSTRACTAccurate staging of nodal involvement in pediatric sarcoma patients is important to determine correct systemic and local therapy, with the goal to reduce subsequent recurrences. However, differences in lymph node staging strategies, definitions, and treatment protocols between the Children's Oncology Group (COG), European paediatric Soft tissue sarcoma Study Group (EpSSG), and the Cooperative Weichteilsarkom Studiengruppe (CWS) complicate comparisons. In this article, we aim to establish internationally recognized recommendations for lymph node assessment and treatment of children and adolescents diagnosed with rhabdomyosarcoma (RMS) and non‐rhabdomyosarcoma soft tissue sarcoma (NRSTS) according to the Consensus Conference Standard Operating Procedure methodology.

Accurate staging of nodal involvement in pediatric sarcoma patients is important to determine correct systemic and local therapy, with the goal to reduce subsequent recurrences. However, differences in lymph node staging strategies, definitions, and treatment protocols between the Children’s Oncology Group (COG), European Pediatric Soft Tissue Sarcoma Study Group (EpSSG), and the Cooperative Weichteil Sarkom Studiengruppe (CWS), complicate comparisons. In this article we try to establish internationally recognized recommendations for lymph node assessment and treatment of children and adolescents diagnosed with RMS and NRSTS according to the Consensus Conference Standard Operating Procedure methodology.

TPS11591 Background: Patients with high-risk rhabdomyosarcoma (HR-RMS) continue to have poor outcomes with 3-year event free survival (EFS) rates of 30% or less despite chemotherapy dose intensification on recent cooperative group RMS trials. Vinorelbine (VINO) has demonstrated clinical activity in RMS patients with relapsed/refractory disease and shown to provide a survival benefit when given with oral cyclophosphamide as maintenance chemotherapy for a select group of patients that achieved first complete remission. Methods: ARST2031 is a randomized Phase 3 trial with the primary aim to compare event-free survival (EFS) of patients with HR-RMS treated with vincristine, dactinomycin and cyclophosphamide (VAC) followed by maintenance with vinorelbine and oral cyclophosphamide (VINO-CPO) or vinorelbine, dactinomycin and cyclophosphamide (VINO-AC) followed by maintenance with VINO-CPO. Patients are stratified by histology and randomly assigned to VAC followed by VINO-CPO maintenance or VINO-AC followed by VINO-CPO maintenance. To be eligible, patients must be ≤ 50 years of age at the time of enrollment with newly diagnosed RMS except adult-type pleomorphic, based upon institutional histopathologic classification. All patients must have Stage 4 disease and patients diagnosed with embryonal RMS (ERMS) must be ≥ 10 years of age. Patients with malignant cytology in cerebrospinal fluid, intra-parenchymal brain metastases, or diffuse leptomeningeal disease are excluded. The study was activated on September 13, 2021 and is anticipated to enroll approximately 4 patients per month. The planned sample size is 100 patients, with approximately 50 patients randomized to each arm. Safety and feasibility of VINO-AC will be assessed in the first 8 patients prior to randomization. The study will have power of 0.8 to detect a hazard ratio of 0.61 (74 events in total) when the one-sided Type I error rate is 0.10, with 30 months of accrual and 2 years of follow-up. The hazard ratio of 0.61 was determined by assuming piecewise exponential distributions and specifying the 2-year EFS of 46% vs. 28% and long-term EFS of 32% vs. 16%, based on prior outcome data. Biospecimens will be collected and banked for future use. Clinical trial information: NCT04994132.

Background Most children with intermediate‐risk rhabdomyosarcoma (RMS) have gross disease (group III) at the initiation of chemotherapy. Delayed primary excision (DPE) after induction chemotherapy allows for a reduction in adjuvant radiation dose, but with the risk of potential surgical morbidity. The objectives of this study were to compare outcomes in children with group III RMS who did and did not undergo DPE and to assess surgical morbidity. Methods The study included 369 patients who had clinical group III RMS at sites amenable to DPE from intermediate‐risk Children's Oncology Group studies D9803 (encouraged DPE) and ARST0531 (discouraged DPE). Results The primary tumor site was bladder/prostate (136 patients; 37%), extremity (97 patients; 26%), trunk (24 patients; 7%), retroperitoneum (91 patients; 25%), or intrathoracic/perineum/perianal (21 patients; 6%). In total, 112 patients (53.9%) underwent DPE in D9803, and 26 patients (16.2%) underwent DPE in ARST0531 ( P < .001), with loss of vital organ or function in 30 of 138 patients (22%). DPE allowed for a reduced radiation dose in 110 of 135 patients (81%; 51% were reduced to 36 Gy, and 30% were reduced to 42 Gy). Patients who underwent DPE had improved unadjusted overall survival ( P = .013). In adjusted regression analysis, the risk of death (hazard ratio, 0.71; 95% CI 0.43‐1.16) was similar for patients who did and did not undergo DPE and was improved for the subset of patients who had tumors of the trunk and retroperitoneum (hazard ratio, 0.44; 95% CI, 0.20‐0.97). Conclusions Children with group III RMS have equivalent or improved outcomes with DPE and can receive a decreased radiation dose for definitive local control. The choice of local control modality should weigh the potential morbidity of surgery versus that of higher dose irradiation.

Background The objective of this study was to evaluate local control for patients with intermediate‐risk rhabdomyosarcoma (RMS) treated on Children's Oncology Group (COG) protocol ARST0531. Methods This study analyzed 424 patients with intermediate‐risk RMS. Patients were randomized to chemotherapy with either vincristine, dactinomycin, and cyclophosphamide (VAC) or VAC alternating with vincristine and irinotecan. With the goal of improving local control, radiation therapy (RT) was delivered early at week 4 and was concurrent with irinotecan in the experimental arm. Individualized local control plans for children 24 months old or younger were allowed. Local failure on ARST0531 was compared with local failure on the preceding COG intermediate‐risk study, D9803. Results For patients with group I/II alveolar RMS (n = 55), the 5‐year cumulative incidence of local failure was 13.4%; for group III alveolar RMS (n = 141), it was 20.2%; and for group III embryonal RMS (n = 228), it was 27.9% ( P = .03). Among patients with group III disease, local failure did not differ by histology, site, nodal status, RT modality, or treatment arm. Local failure was worse for a tumor size >5 cm (32.3% vs 16.7%; P = .001). Among patients with group III embryonal RMS, local failure was higher on ARST0531 than D9803 (27.9% vs 19.4%; P = .03). After the exclusion of patients 24 months old or younger or patients who did not receive radiation, local failure remained significantly increased on ARST0531 ( P = .02). After adjustments for clinical prognostic factors, event‐free survival and overall survival were worse on ARST0531 ( P = .004 and P = .05, respectively). Conclusions Despite interventions designed to enhance local control, local control was inferior on ARST0531 in comparison with D9803. The reason for this is unclear, but it could be the reduced cyclophosphamide dose on ARST0531.