Shatara, Margaret

Abstract BACKGROUND Primary intracranial germ cell tumors (GCTs) are rare heterogeneous tumors; germinoma accounts for two-thirds of cases. While neoadjuvant chemotherapy followed by response-based reduced radiotherapy dose and field is the established approach for managing localized CNS germinomas, controversy persists regarding the treatment of primary metastatic disease. Additionally, limited research exists on the utilization of neoadjuvant chemotherapy in primary metastatic germinoma. METHODS A retrospective multi-institutional analysis was conducted to assess overall survival (OS) and event-free survival (EFS) among patients diagnosed with metastatic germinoma who were treated with various modalities. RESULTS We identified 88 patients, including 63 males and 25 females. The median age at presentation was 13.5 years. All patients, who had undergone both brain and spine MRIs, had their diagnoses confirmed through a biopsy, positive CSF cytology, and/or positive CSF tumor markers at presentation. Primary Tumor location was pineal (n=37), suprasellar (n=27), bifocal (n=14) and others (n=9). Eight patients underwent subtotal resection. Craniospinal irradiation (CSI; 21-24 Gy) was administered to 71 patients (81%), while eight patients (9%) received whole ventricular irradiation (WVI; 23.4-30 Gy). Whole brain radiation was given to four patients (5%; 24 Gy), and two patients (2%) had unknown fields. Boosts to primary and/or metastatic sites were administered in all but seven patients. Notably, thirty patients (34%) received CSI without neoadjuvant chemotherapy. At the end of therapy, 69 patients had complete response, 10 partial response and the response was unknown in six. Three patients did not receive irradiation, all died of disease progression. The median follow-up was 64 months (range 6-159 months), yielding an OS of 96.6%. Ongoing multi-institutional data collection and analysis will be presented at the meeting. CONCLUSION Our study is one of the largest studies to date in metastatic germinoma and may provide insight into the role of neoadjuvant chemotherapy with lower CSI doses.

Abstract Background Patients with relapsed intracranial germinoma can achieve durable remission with standard chemotherapy regimens and/or reirradiation; however, innovative therapies are required for patients with relapsed and/or refractory intracranial nongerminomatous germ cell tumors (NGGCTs) due to their poor prognosis. Improved outcomes have been reported using reinduction chemotherapy to achieve minimal residual disease, followed by marrow-ablative chemotherapy (HDCx) with autologous hematopoietic progenitor cell rescue (AuHPCR). We conducted a phase II trial evaluating the response and toxicity of a 3-drug combination developed for recurrent intracranial germ cell tumors consisting of gemcitabine, paclitaxel, and oxaliplatin (GemPOx). Methods A total of 9 patients with confirmed relapsed or refractory intracranial GCT were enrolled after signing informed consent, and received at least 2 cycles of GemPOx, of which all but 1 had relapsed or refractory NGGCTs. One patient with progressive disease was found to have pathologically confirmed malignant transformation to pure embryonal rhabdomyosarcoma (without GCT elements), hence was ineligible and not included in the analysis. Patients who experienced sufficient responses proceeded to receive HDCx with AuHPCR. Treatment response was determined based on radiographic tumor assessments and tumor markers. Results A total of 7 patients achieved sufficient response and proceeded with HDCx and AuHPCR, and 5 subsequently received additional radiotherapy. A total of 2 patients developed progressive disease while receiving GemPOx. Myelosuppression and transaminitis were the most common treatment-related adverse events. With a mean follow-up of 44 months, 4 patients (3 NGGCTs, 1 germinoma) are alive without evidence of disease. Conclusions GemPOx demonstrates efficacy in facilitating stem cell mobilization, thus facilitating the feasibility of both HDCx and radiotherapy.

Abstract Background: The discovery of the driving oncogenic alterations in pediatric low-grade gliomas (pLGGs) has shifted our focus towards management with targeted therapies, especially in relapsing or progressive disease. Limited data is available on the durability of response to targeted therapy in pLGGs once the therapy has ceased. Methods: Multi-institutional retrospective chart review of patients with pLGGs younger than 25 years, between 2010-2021, was undertaken to evaluate the durability of response to targeted therapy and determine risk factors associated with disease progression after cessation of therapy. Results: Current analysis included 18 patients from two centers. Seven (39%) had neurofibromatosis type-1 (NF-1). Diagnoses included: optic pathway glioma (OPG) (6/18, 33%), pilocytic astrocytoma (8/18, 44%), diffuse fibrillary astrocytoma (1/18), ganglioglioma (1/18), glioneural neoplasm (2/18). Sixteen patients received at least one prior line of chemotherapy (range 1-5). Targeted agents included trametinib (50%), selumetinib (5%), binimetinib (22%), vemurafenib (11%) and everolimus (11%). Median time on therapy was 351 days (range 29-979 days). All, but one patient had residual intracranial findings at the end of therapy: eight patients (44%) had stable disease, while ten required additional therapy; 50% were NF-1 patients with OPG. Median time to progression was 203 days (range 29-615 days). Of those who did not require any additional therapies, 50% had suprasellar tumors. Genomic data was available for twelve patients; BRAF-KIAA1549 fusion was the most common genomic alteration. Others included mutations in KRAS, BRAF (V600E), PTPN11, SOX6-RAF1 fusion, NF-1, and a patient with FGFR1, KMT2C, and PTPN11 alterations. Conclusion: Preliminary analysis demonstrates that despite initial response, the majority of patients required additional line of therapy. Patients with NF-1 and OPGs tend to progress after discontinuing therapy, while suprasellar non-NF1 pLGGs tend to develop sustained response to targeted therapies. Additional multi-institutional analysis is underway and will be presented at the meeting.

Abstract BACKGROUND: Primary intracranial germ cell tumors (GCTs) are rare heterogeneous tumors, with germinoma accounting for two-thirds of cases. Neoadjuvant chemotherapy with response-based reduced radiotherapy dose and field has become the standard management of localized CNS germinomas, however, treatment of primary metastatic disease has remained controversial. Furthermore, there is limited published research on the use of neoadjuvant chemotherapy in primary metastatic germinoma. METHODS: We performed a retrospective multi-institutional data collection and analysis of patients diagnosed with metastatic germinoma since 2000 to assess the overall survival (OS) and event-free survival (EFS) of the different treatment modalities administered. RESULTS: We identified 78 patients with germinoma, in two tertiary care centers, of which nine patients (11.5%; eight males) had metastatic disease. The median age at presentation was 13.3 years. All patients had a biopsy at presentation confirming the diagnosis. Three patients had positive CSF cytology (M1). Six patients received craniospinal irradiation (CSI) with boost to primary and metastatic sites, of which five patients received total CSI dose of 24 Gy, while the dose was unknown for one patient. One patient required one cycle of chemotherapy prior to CSI due to worsening visual changes, which subsequently resolved. One patient received two cycles followed by whole ventricular irradiation (WVI) of 23.4 Gy with a boost to the primary bed. One patient received WVI without neoadjuvant chemotherapy. One patient developed anoxic brain injury and only received chemotherapy. He died of recurrent progressive disease 15 months post-diagnosis. The median follow-up time was 77.5 months (range 15-130.5 months), with an OS of 88.9%. Further multi-institutional data collection and analysis is underway and will be presented at the meeting. CONCLUSION: We anticipate our results may elucidate the role of neoadjuvant chemotherapy in the treatment of metastatic germinoma, and whether when combined with lower CSI doses did not compromise EFS/OS.