Babovic‐Vuksanovic, Dusica

3016 Background: PN in patients (pts) with NF1 can cause pain, disfigurement, impaired quality of life (QoL), and can undergo malignant transformation. ReNeu (NCT03962543), a multicenter, open-label, Phase 2b study, evaluated efficacy and safety of the highly selective, oral, investigational MEK1/2 inhibitor mirdametinib in adult (≥18 y) and pediatric (2-17 y) pts with inoperable NF1 PN causing significant morbidities. Methods: Mirdametinib was administered as a capsule or dispersible tablet (2 mg/m 2 BID, max 4 mg BID) without regard to food in 3 wk on/1 wk off 28-d cycles. The primary endpoint was confirmed objective response rate (ORR; percentage of pts with MRI-assessed ≥20% reduction of target PN volume by blinded independent central review [BICR] within the 24-cycle treatment phase). The minimum clinically relevant ORR (null) was defined as 23% for adults and 20% for pediatrics. Ptscould continue treatment in an optional long-term follow-up (LTFU) phase. Additional key endpoints were duration of response (DoR), time to response (TTR), change from baseline (BL) in target PN volume, pain severity (Numerical Rating Scale-11 [NRS-11]), pain interference (Pain Interference Index [PII]), health-related (HR) QoL (PedsQL), and safety. Results: All114 pts (58 adult, 56 pediatric) received mirdametinib. As of the 20 Sept 2023 data cutoff (DCO), BICR-confirmed ORR during the treatment phase was 41% (95% CI, 29-55; P<.001 vs null) in adults and 52% (95% CI, 38-65; P<.001 vs null) in pediatric pts. Two adult pts and 1 pediatric pt also had a confirmed response in the ongoing LTFU. Median (min, max) target PN volumetric best response from BL was -41% (-90, 13) and -42% (-91, 48) in adult and pediatric pts, respectively. As of the DCO, median treatment duration was 22 mo for each cohort and median DoR was not reached. Median (range) TTR was 7.8 (4-19) mo in adult pts and 7.9 (4-19) mo in pediatric pts. Adult and pediatric pts had statistically significant improvements from BL to cycle 13 in NRS-11, PII, and key PedsQL measures. Most frequent (≥35% pts) treatment-emergent adverse events (TEAEs) were dermatitis acneiform, diarrhea, nausea, and vomiting in adults and diarrhea, dermatitis acneiform, and vomiting in pediatric pts. 16% and 25% of adult and pediatric pts, respectively, had grade ≥3 treatment-related AEs, and 22% and 9%, respectively, discontinued due to TEAEs. Conclusions: In ReNeu, the largest multicenter NF1 PN trial reported to date, mirdametinib demonstrated a statistically significant ORR by BICR, with deep and durable PN volume reductions, significant improvements in pain severity, pain interference, and HRQoL, and a manageable safety profile in both adults and children. Together with a dispersible tablet formulation, these results underscore mirdametinib’s potential to become an important new treatment option for NF1 PN pts across all ages. Clinical trial information: NCT03962543 .

Abstract INTRODUCTION NF2-related schwannomatosis (NF2-SWN) predisposes affected individuals to vestibular schwannomas (VS), non-vestibular schwannomas (NVS), meningiomas, and ependymomas. The rarity of NF2-SWN and the presence of multiple tumor types has impeded clinical trials. We conducted a multi-center, adaptive, platform-basket trial to screen multiple drugs against progressive NF2-SWN tumors. We report the final analysis of the first treatment arm with brigatinib, an oral ALK inhibitor that inhibits multiple tyrosine kinases. METHODS This study enrolled participants ≥ 12 years with NF2-SWN and progressive target tumors (baskets: VS, NVS, meningioma, or ependymoma Radiographic response (RR) was defined as ≥ 20% decrease in target tumor volume from baseline. The primary outcome was RR rate. Secondary outcomes included safety, hearing response, and RR in non-target tumors. Tumor response was evaluated by MRI every 3 months in year 1 and every 6 months thereafter. In stage 1, 20 participants received brigatinib 180 mg daily. Interim analysis suggested activity in NVS and meningioma. Thus, an additional 20 participants with progressive meningioma or NVS were enrolled in stage 2. RESULTS Forty participants (median age 26 years, 12 pediatric, 28 female) were treated. Prior treatment included surgery (90%), radiation therapy (20%) and chemotherapy (55%). Target tumors included 10 VS, 9 NVS, 19 meningiomas, and 2 ependymomas. Overall RR rate was 10% for all target tumors (22% for non-VS, 11% for meningioma, 0% for VS, and 0% for ependymomas). There were no grade 4 or 5 treatment-related adverse events (AEs). The most common AEs were diarrhea (63%), nausea (40%), muscle cramps (33%), increased LDH (35%), increased AST (33%), and increased ALT (23%). CONCLUSION Brigatinib treatment was associated with RR in NVS and meningiomas in a heavily pretreated cohort of participants with progressing NF2-SWN tumors. This novel design provides unique ability to assess treatments for hereditary syndromes with multiple primary tumors.

Abstract Introduction: Most rare disease patients (75 − 50%) undergoing genomic sequencing remain unsolved, often due to lack of information about variants identified. Data review over time can leverage novel information regarding disease-causing variants and genes, increasing this diagnostic yield. However, time and resource constraints have limited reanalysis of genetic data in clinical laboratories setting. We developed RENEW, (REannotation of NEgative WES/WGS) an automated reannotation procedure that uses relevant new information in on-line genetic databases to enable rapid review of genetic findings. Methods We tested RENEW in an unselected cohort of 1,066 undiagnosed cases from the Mayo Clinic Center for Individualized Medicine using new information in ClinVar, HGMD and OMIM between the date of previous analysis/testing and April of 2022. Results 5,741 variants prioritized by RENEW were rapidly reviewed by variant interpretation specialists. Mean analysis time was approximately 20 seconds per variant (32 hours total time). Reviewed cases were classified as: 879 (93.0%) undiagnosed, 63 (6.6%) putatively diagnosed, and 4 (0.4%) definitively diagnosed. Discussion New strategies are needed to enable efficient review of genomic findings in unsolved cases. We report on a fast and practical approach to address this need and improve overall diagnostic success in patient testing through a recurrent reannotation process.

Aortic dissection is often a fatal condition if not recognized and treated emergently. Fortunately, it is extremely rare in children and adolescents. We report a case of an adolescent boy who survived an aortic dissection due to severe aortic root dilation. A comprehensive history and physical examination, including family history, can facilitate an early diagnosis of connective tissue diseases, such as Loeys-Dietz syndrome (LDS).

Abstract Neurofibromatosis type 2 (NF2) predisposes affected individuals to vestibular schwannomas (VS), non-vestibular schwannomas (NVS), meningiomas, and ependymomas. We developed an adaptive platform-basket trial to screen multiple drugs against any type of progressive NF2-related tumor. We report the interim analysis of the first treatment arm with brigatinib, an ALK inhibitor that inhibits multiple tyrosine kinases. We conducted a multicenter, phase II, open-label study for subjects ≥12 years old with NF2 and progressive target tumors (baskets: VS, NVS, meningioma, or ependymoma). Up to 5 non-target tumors were followed in each participant. In stage 1, 20 participants (minimum of 2 participants per basket) were treated with brigatinib 180 mg daily. Tumor response was evaluated by MRI every 3 months in year 1 and every 6 months thereafter. Radiographic response (RR) was defined as ≥20% decrease in target tumor volume from baseline. The primary outcome was RR rate. Per protocol, the brigatinib arm would be discontinued if no target tumor achieved a RR at interim analysis. Twenty subjects (median age=25 years, 7 pediatric, 12 females) were treated. Target tumors included 10 VS, 3 NVS, 5 meningiomas, and 2 ependymomas; non-target tumors included 18 VS, 36 NVS, and 14 meningiomas. RR rate for target and non-target tumors was 5% and 22%, respectively. By tumor basket, RR was 28% for meningioma, 26% for non-VS, 4% for VS, and 0% for ependymomas. Annualized tumor growth rates decreased for VS, NVS, and meningioma during treatment. Brigatinib was well tolerated with one dose reduction and one discontinuation due to grade 2 diarrhea. Brigatinib treatment was associated with RR in meningiomas, VS, and NVS. In stage 2, the study will enroll 20 participants in the two most promising baskets (meningioma and NVS). This novel design provides unique ability to assess treatments for hereditary syndromes with multiple primary tumors.

Abstract BACKGROUND The Food and Drug Administration recently issued guidance on conducting qualitative research to support patient-focused drug development. In prior FDA submissions, qualitative data has been critical to demonstrate the content validity of and meaningfulness of change in quantitative trial endpoints. Qualitative patient interviews embedded within neuro-oncology trials can supplement traditional quantitative measures by providing nuanced information on patients’ treatment priorities, benefit/risk assessments, and quality of life. METHODS We interviewed people with neurofibromatosis 2 (NF2) in stage one of the brigatinib arm of a multicenter, phase II, adaptive platform-basket trial for progressive NF2-related tumors (NCT04374305). Transcripts were coded by two analysts using a hybrid inductive/deductive framework; cross-cutting themes were generated using the Framework Method. RESULTS 16/20 trial enrollees participated in interviews May 2021-March 2022. The radiographic response rate (volume shrinkage ≥20% from baseline) at 6 months for target and non-target tumors was 5% and 22%, respectively. However, most participants rated their change in overall status as minimally (10/16) or much (3/16) improved. Several participants acknowledged their tumor size had not changed significantly but felt tumor stability was an improvement over previously accelerated growth rates; this importantly allowed them to avoid or postpone future surgery. Participants also valued prevention of symptomatic decline, minimal impact of side effects on social roles and activities, the convenience of oral medication, and the sense of hope and agency gained from participating in a trial. CONCLUSIONS Virtual, in-depth qualitative interviews were feasible across multiple sites and provided unique information on NF2 patients’ conceptualization of clinical benefit. Qualitative interviews embedded within neuro-oncology trials can reveal 1) whether trial design and choice of outcome measures align with patient priorities; 2) whether and how new treatments improve patients’ quality of life; and 3) what degree of change in quantitative measures such as radiographic progression are clinically meaningful.

The chromokinesin KIF22 generates forces that contribute to mitotic chromosome congression and alignment. Mutations in the α2 helix of the motor domain of KIF22 have been identified in patients with abnormal skeletal development, and we report the identification of a patient with a novel mutation in the KIF22 tail. We demonstrate that pathogenic mutations do not result in a loss of KIF22’s functions in early mitosis. Instead, mutations disrupt chromosome segregation in anaphase, resulting in reduced proliferation, abnormal daughter cell nuclear morphology, and, in a subset of cells, cytokinesis failure. This phenotype could be explained by a failure of KIF22 to inactivate in anaphase. Consistent with this model, constitutive activation of the motor via a known site of phosphoregulation in the tail phenocopied the effects of pathogenic mutations. These results suggest that the motor domain α2 helix may be an important site for regulation of KIF22 activity at the metaphase to anaphase transition. In support of this conclusion, mimicking phosphorylation of α2 helix residue T158 also prevents inactivation of KIF22 in anaphase. These findings demonstrate the importance of both the head and tail of the motor in regulating the activity of KIF22 and offer insight into the cellular consequences of preventing KIF22 inactivation and disrupting force balance in anaphase.