Hawkins, Douglas S

AbstractChildren and adolescents with rhabdomyosarcoma (RMS) comprise a heterogeneous population with variable overall survival rates ranging between approximately 6% and 100% depending on defined risk factors. Although the risk stratification of patients has been refined across five decades of collaborative group studies, molecular prognostic biomarkers beyond FOXO1 fusion status have yet to be incorporated prospectively in upfront risk‐based therapy assignments. This review describes the evolution of risk‐based therapy and the current risk stratification, defines a new risk stratification incorporating novel biomarkers, and provides the rationale for the current and upcoming Children's Oncology Group RMS studies.

PURPOSE The primary aim of this phase III randomized trial was to test whether the addition of vincristine, topotecan, and cyclophosphamide (VTC) to interval compressed chemotherapy improved survival outcomes for patients with previously untreated nonmetastatic Ewing sarcoma. METHODS Patients were randomly assigned to receive standard five-drug interval compressed chemotherapy (regimen A) for 17 cycles or experimental therapy with five cycles of VTC within the 17 cycles (regimen B). Patients were stratified by age at diagnosis (< 18 years and ≥18 years) and tumor site (pelvic bone, nonpelvic bone, and extraosseous). Tumor volume at diagnosis was categorized as < 200 mL or ≥ 200 mL. Local control occurred following six cycles. Histologic response was categorized as no viable or any viable tumor. Event-free survival (EFS) and overall survival (OS) were compared between randomized groups with stratified log-rank tests. RESULTS Of 642 enrolled patients, 309 eligible patients received standard and 320 received experimental therapy. The 5-year EFS and OS were 78% and 87%, respectively. There was no difference in survival outcomes between randomized groups (5-year EFS regimen A v regimen B, 78% v 79%; P = .192; 5-year OS 86% v 88%; P = .159). Age and primary site did not affect the risk of an EFS event. However, age ≥ 18 years was associated with an increased risk of death at 5 years (hazard ratio 1.84; 95% CI, 1.15 to 2.96; P = .009). The 5-year EFS rates for patients with pelvic, nonpelvic bone, and extraosseous primary tumors were 75%, 78%, and 85%, respectively. Tumor volume ≥ 200 mL was significantly associated with lower EFS. CONCLUSION While VTC added to five-drug interval compressed chemotherapy did not improve survival, these outcomes represent the best survival estimates to date for patients with previously untreated nonmetastatic Ewing sarcoma.

ARST1321, a trial of patients with advanced soft tissue sarcoma, was the first National Clinical Trials Network study codeveloped by pediatric and adult consortia with two treatment cohorts. We report on the findings of a survey to identify barriers to enrolling adolescent and young adult patients (15–39 years) onto the nonchemotherapy arm. The survey response rate was 31% with a 70% completion rate. Common identified reasons for low accrual in order of decreasing frequency included insufficient funding, lack of study awareness or interest, competing trials, toxicity concerns, philosophical differences in the therapy backbone, and regulatory and infrastructure barriers. Clinical Trials.gov ID: NCT02180867.

Rhabdomyosarcoma is the most common soft tissue sarcoma diagnosed in children and adolescents. Patients that are diagnosed with advanced or relapsed disease have exceptionally poor outcomes. The Children’s Oncology Group (COG) convened a rhabdomyosarcoma new agent task force in 2020 to systematically evaluate novel agents for inclusion in phase 2 or phase 3 clinical trials for patients diagnosed with rhabdomyosarcoma, following a similar effort for Ewing sarcoma. The task force was comprised of clinicians and basic scientists who collectively identified new agents for evaluation and prioritization in clinical trial testing. Here, we report the work of the task force including the framework upon which the decisions were rendered and review the top classes of agents that were discussed. Representative agents include poly-ADP-ribose polymerase (PARP) inhibitors in combination with cytotoxic agents, mitogen-activated protein kinase (MEK) inhibitors in combination with type 1 insulin-like growth factor receptor (IGFR1) inhibitors, histone deacetylase (HDAC) inhibitors, and novel cytotoxic agents.

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.

Abstract The International Soft‐Tissue Sarcoma Consortium (INSTRuCT) was founded as an international collaboration between different pediatric soft‐tissue sarcoma cooperative groups (Children's Oncology Group, European Pediatric Soft‐Tissue Sarcoma Group, and Cooperative Weichteilsarkom Studiengruppe). Besides other tasks, a major goal of INSTRuCT is to develop consensus expert opinions for best clinical treatment. This consensus paper for patients with rhabdomyosarcoma of the female genital tract (FGU‐RMS) provides treatment recommendations for local treatment, long‐term follow‐up, and fertility preservation. Therefore, a review of the current literature was combined with recommendations of the treatment protocols of the appropriate clinical trials. Additionally, opinions of international FGU‐RMS experts were incorporated into recommendations. Results were that the prognosis of FGU‐RMS is favorable with an excellent response to chemotherapy. Initial complete surgical resection is not indicated, but diagnosis should be established properly. In patients with tumors localized at the vagina or cervix demonstrating incomplete response after induction chemotherapy, local radiotherapy (brachytherapy) should be carried out. In patients with persistent tumors at the corpus uteri, hysterectomy should be performed. Fertility preservation should be considered in all patients. In conclusion, for the first time, an international consensus for the treatment of FGU‐RMS patients could be achieved, which will help to harmonize the treatment of these patients in different study groups.

Background The International Soft Tissue Sarcoma Consortium (INSTRuCT) was founded as an international collaboration between different pediatric soft tissue sarcoma cooperative groups (COG, EpSSG, CWS). Besides other tasks, a major goal of the INSTRuCT is to develop consensus expert opinions for best clinical treatment. This consensus paper for patients with rhabdomyosarcoma of the female genital tract (FGU-RMS) provides treatment recommendations for local treatment, long term follow up and fertility preservation. Methods Review of the current literature was combined with recommendations of the treatment protocols of the appropriate clinical trials. Additionally, opinions of international FGU-RMS experts were incorporated into recommendations. Results The prognosis of FGU-RMS is favorable with an excellent response to chemotherapy. Initial complete surgical resection is not indicated, but diagnosis should be established properly. In patients with tumors localized at the vagina or cervix demonstrating incomplete response after induction chemotherapy, local radiotherapy (brachytherapy) should be carried out. In patients with persistent tumors at the corpus uteri, hysterectomy should be performed. Fertility preservation should be considered in all patients. Conclusion For the first time, an international consensus for the treatment of FGU-RMS patients could be achieved, which will help to harmonize the treatment in different study groups.

Abstract Paratesticular rhabdomyosarcoma (PT‐RMS) carries a favorable prognosis, but questions persist regarding optimal management. Our goal was to determine the importance of primary tumor resection and surgical assessment of retroperitoneal lymph nodes during staging in patients with PT‐RMS. We analyzed patients with localized PT‐RMS enrolled onto one of four Children's Oncology Group studies (D9602, ARST0331, D9803 or ARST0531). Surgical resection of the primary tumor prior to chemotherapy and radiotherapy was encouraged when possible with retroperitoneal lymph node dissection (RPLND) recommended for patients ≥10 years of age. Among 279 patients (median 8.1 years old), most tumors were resected with negative margins (78.5%) and most patients did not have radiographic enlargement of regional lymph nodes (90.3%). In patients older than 10 years, imaging alone will miss over 51.5% of nodal disease. Five‐year event‐free survival (EFS) was 92.0% (95% CI 88.4%‐95.6%). Sampling ≥7 to 12 retroperitoneal lymph nodes appeared optimal for detecting positive nodes; while there was a trend toward improved EFS among those undergoing template RPLND, this was not statistically significant ( P = .068). Age ( P = .28), N‐stage ( P = .39), T‐stage ( P = .11) and pathologic node involvement ( P = .53) were not associated with overall survival. However, older age and larger tumor size had an additive impact on EFS ( P = .027) though not overall survival ( P = .13). In conclusion, outcomes for patients with PT‐RMS are excellent. Reliance on imaging to detect nodal involvement will miss pathologic node involvement and may result in undertreatment. Surgical nodal staging requires at least 7 to 12 nodes to accurately identify patients with regional nodal disease.

Abstract Background Previous studies of the prognostic importance of FOXO1 fusion status in patients with rhabdomyosarcoma (RMS) have had conflicting results. We re‐examined risk stratification by adding FOXO1 status to traditional clinical prognostic factors in children with localized or metastatic RMS. Methods Data from six COG clinical trials (D9602, D9802, D9803, ARST0331, ARTS0431, ARST0531; two studies each for low‐, intermediate‐ and high‐risk patients) accruing previously untreated patients with RMS from 1997 to 2013 yielded 1727 evaluable patients. Survival tree regression for event‐free survival (EFS) was conducted to recursively select prognostic factors for branching and split. Factors included were age, FOXO1, clinical group, histology, nodal status, number of metastatic sites, primary site, sex, tumor size, and presence of metastases in bone/bone marrow, soft tissue, effusions, lung, distant lymph nodes, and other sites. Definition and outcome of the proposed risk groups were compared to existing systems and cross‐validated results. Results The 5‐year EFS and overall survival (OS) for evaluable patients were 69% and 79%, respectively. Extent of disease (localized versus metastatic) was the first split (EFS 73% vs 30%; OS 84% vs. 42%). FOXO1 status (positive vs negative) was significant in the second split both for localized (EFS 52% vs 78%; OS 65% vs 88%) and metastatic disease (EFS 6% vs 46%; OS 19% vs 58%). Conclusions After metastatic status, FOXO1 status is the most important prognostic factor in patients with RMS and improves risk stratification of patients with localized RMS. Our findings support incorporation of FOXO1 status in risk stratified clinical trials.

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.