Citations

Abstract Intrinsic brainstem tumors arising in pediatric, adolescent, and young adult patients comprise a spectrum of entities, predominantly diffuse midline gliomas (DMG) and IDH mutant astrocytomas. Accurate molecular diagnosis is essential for prognostication and optimal therapy. Therapeutic considerations include inclusion (in IDH mutant) or exclusion (in H3K27M) of adjuvant Temozolomide post radiotherapy and use of molecular targeted therapy (IDH inhibitors). Surgical biopsy, however, is associated with increased risk of permanent neurological deficits and may yield insufficient or non-diagnostic tissue. We hypothesized that minimally-invasive “liquid biopsy” of cerebrospinal fluid (CSF) could represent a superior diagnostic modality in this patient population, employing molecular analysis of cell free DNA (cfDNA). We analyzed 44 CSF samples from 38 unique patients for recurrent driver mutations in brainstem gliomas, including H3K27M, IDH1, and IDH2. MSK-IMPACT, a NY state-authorized hybridization capture-based next-generation panel DNA sequencing assay, was used for analysis. Samples without a detectable driver mutation by MSK-IMPACT testing were further subjected to gene targeted testing by droplet digital PCR. In all, 10/44 (22.7%) samples had mutations detected by MSK-IMPACT using standard calling criteria and 13 of the remaining 34 samples (38.2%) had supporting evidence of a mutation based on manual review. Further testing by ddPCR was performed on a subset of cases (based on DNA availability) which confirmed 7 of the previous low-level mutations and uncovered 4 additional mutations. Overall, 27/44 (61.4%) of cases had detectable evidence of a mutation, and of the 23 patients without a known tissue diagnosis, a driver in the CSF was identified for 47.8% of patients (11/23). Minimally-invasive analysis of CSF cfDNA in patients with intrinsic brainstem tumors has a high diagnostic yield and may obviate the need for tissue biopsy in a majority of patients. Testing with high sensitivity assays is valuable to maximize the rate of detection.

AbstractIntroductionWe examined neuropsychiatric symptoms (NPS) and psychotropic medication use in a large sample of individuals with early‐onset Alzheimer's disease (EOAD; onset 40‐64 years) at the midway point of data collection for the Longitudinal Early‐onset Alzheimer's Disease Study (LEADS).MethodsBaseline NPS (Neuropsychiatric Inventory – Questionnaire; Geriatric Depression Scale) and psychotropic medication use from 282 participants enrolled in LEADS were compared across diagnostic groups – amyloid‐positive EOAD (n = 212) and amyloid negative early‐onset non‐Alzheimer's disease (EOnonAD; n = 70).ResultsAffective behaviors were the most common NPS in EOAD at similar frequencies to EOnonAD. Tension and impulse control behaviors were more common in EOnonAD. A minority of participants were using psychotropic medications, and use was higher in EOnonAD.DiscussionOverall NPS burden and psychotropic medication use were higher in EOnonAD than EOAD participants. Future research will investigate moderators and etiological drivers of NPS, and NPS differences in EOAD versus late‐onset AD.

9093 Background: Pembrolizumab interrupts PD-1/-L1 interaction and is efficacious in many cancers. However, resistance invariably emerges in the majority of patients. Potential mechanisms include activation of compensatory pathways. The inhibition of sonic hedgehog signaling (sHH) was previously shown to induce intra-tumoral (IT) infiltration by CD4+, CD8+ and HLA-DR class II cells. Our preclinical data showed sHH inhibitor enhanced IT penetration by monoclonal antibodies and induced PD-L1 expression. We conducted a phase I study using a novel sequential pulse dosing of sonedegib followed by pembrolizumab in aST with an expansion cohort to determine the maximum tolerated dose (MTD), tolerability and preliminary efficacy. Methods: The dose escalation utilized a 3+3 design to determine the MTD and proceeded to expansion cohort upon determination of the MTD. Patients enrolled to each dose level were observed for dose limiting toxicities (DLTs) during the 1st cycle. The expansion cohort consisted of NSCLC and head/neck squamous cell carcinoma (HNSCC) previously treated by anti-PD1/-L1. The recommended phase 2 dose (RP2D) was determined following the review of the toxicity profile of the combination from all cycles. The study treatment consisted of sonidegib oral daily from day 1 to 8 and pembrolizumab I.V. 200 mg on day 8 on an every 3-week cycle. The sonidegib dose levels explored were 400, 600 and 800 mg. Archival tumor and blood specimens were collected for correlative studies. Adverse events (AEs) were categorized and graded per CTCAE v5.0, and tumor response by RECIST v1.1. Results: The study enrolled a total of 33 patients and 29 received treatment (13 in escalation and 16 in expansion), including patients with NSCLC, HNSCC, skin cancer, gastric cancer and melanoma. The enrollment to the NSCLC cohort is complete and HNSCC continues. No DLT was encountered during dose escalation and the MTD was not reached. The highest planned dose level was selected to proceed to expansion (sonidegib 800mg days 1-8 in combination with pembrolizumab I.V. 200 mg on day 8 on an every 3-week cycle). The expansion cohort proceeded to enroll 15 patients evaluable for AEs (10 NSCLC and 5 HSNCC). Grade 3 and above treatment-related AEs across all patients were hyperglycemia, fatigue, dyspepsia, abdominal pain. The mature efficacy data will be reported at the meeting. Conclusions: The study successfully determined the RP2D of sonidegib when dosed sequentially with pembrolizumab in advanced solid tumors. The AE profile of the combination is similar to that for respective agents given individually. The efficacy data among anti-PD1/-PDL1-treated NSCLC will be reported at the meeting. Clinical trial information: NCT04007744 .

8037 Background: Both daratumumab in combination with lenalidomide and dexamethasone (DRd) and bortezomib in combination with lenalidomide and dexamethasone (VRd) are endorsed by NCCN guidelines as preferred regimens for the treatment of transplant-ineligible (TIE) patients with newly diagnosed multiple myeloma (NDMM). DRd and VRd have each demonstrated superior efficacy relative to lenalidomide and dexamethasone (Rd) alone in the MAIA and SWOG S0777 trials, respectively, but have not been compared directly in a head-to-head trial. Naive comparisons of efficacy across the 2 trials may be biased because MAIA enrolled only TIE patients (median age 73 years), whereas S0777 enrolled a mixed transplant-not-intended (TNI) population, which included both TIE patients and patients choosing to defer/refuse frontline stem cell transplantation (median age 63 years). Methods: The present study leveraged individual patient-level data (IPD) from both trials to perform an anchored indirect treatment comparison of DRd vs VRd, adjusting for differences in trial eligibility criteria and baseline patient characteristics. Harmonized inclusion criteria (NDMM, age ≥65 years, ECOG performance status ≤2) were applied to both trial populations. Age ≥65 years served as a proxy for TIE status since S0777 enrolled a mixed TNI population. Propensity score (PS) reweighting was used to balance the 2 trial populations on key baseline prognostic factors including age, sex, ISS stage, ECOG performance status, hemoglobin, eGFR, lactate dehydrogenase (LDH) level, and cytogenetic risk. Missing data were addressed with multiple imputation. After alignment of inclusion criteria and PS reweighting, an anchored indirect comparison was performed wherein within-trial progression-free survival (PFS) hazard ratios (HRs) for DRd vs Rd and VRd vs Rd were estimated and used to make indirect inference about PFS for DRd vs VRd. Results: 727 MAIA participants and 198 S0777 participants were eligible for inclusion. After PS reweighting, the trial populations were balanced on the key baseline prognostic factors identified above (standardized difference < 0.1 for each). The adjusted PFS HRs were 0.53 (95% CI: 0.41–0.68; P< 0.0001) for DRd vs Rd in MAIA and 0.88 (0.63–1.23; P= 0.46) for VRd vs Rd in S0777. In the adjusted Rd-anchored indirect comparison, the PFS HR for DRd vs VRd was 0.60 (0.39–0.90; P= 0.02). Conclusions: In this adjusted indirect treatment comparison based on IPD from the MAIA and S0777 trials, PFS was significantly longer for DRd relative to VRd. In the absence of a head-to-head trial comparing DRd and VRd, the present study may help to inform treatment selection in TIE patients with NDMM.

e19530 Background: In large B-cell lymphoma (LBCL) trials, racial and ethnic representation is difficult to determine due to underreporting in some regions, or because some patients may not provide data. It is difficult to understand the full extent of any underrepresentation of specific races or ethnicities in these trials relative to the prevalence of LBCL in clinical practice. The objective of this study was to characterize racial and ethnic representation in LBCL real-world databases and recently published LBCL studies. Methods: Analyses of the distribution of different racial and ethnic categories were conducted across 6 real-world clinical practice databases from the United States (US): SEER-Medicare, COTA, Medicare, Optum Market Clarity, Optum CDM, and ConcertAI RWD. In addition, a targeted review of recently published studies in patients with LBCL was conducted to identify reported race and ethnicity distributions. Distributions were described using counts and percentages for each race (Asian, Black, White, and other/unknown/not reported) and ethnicity (Hispanic, non-Hispanic, and other/unknown/not reported) category. Results: Patients with LBCL from the databases included: COTA (N=5848), SEER-Medicare (N=102,548), Medicare (N=136,466), Optum Market Clarity (N=19,649), Optum CDM (N=22,175), and ConcertAI (N=1828). Race and ethnicity distributions are reported in the table. Across databases, Asian (2–6%) and Black (5–8%) races were substantially lower than White race (69–88%). Across various lines of therapy, distributions were similar: 3–5% Asian, 3–5% Black, and 78–82% White. Hispanic ethnicity (5–22%) was substantially lower than non-Hispanic ethnicity (70–91%). In the targeted review, 14 publications of LBCL therapies were identified; of these, 10 did not report racial/ethnic composition. In 4 publications (Salles et al, 2020; Sehn et al, 2020; Bannerji et al, 2022; and a real-world study by Shenoy et al, 2011), Asian, Black, White, and other/unknown/not reported represented 2–13%, 0–7%, 71–89%, and 1–11%, respectively. Conclusions: Information on racial and ethnic distributions in LBCL studies is underreported, particularly in global trials. If this information was reported and reflective of LBCL in clinical practice in the US, the numbers of Asian and Black patients would be low at ≤8%, and most patients would be expected to be White and non-Hispanic. [Table: see text]

e15131 Background: Elimusertib is a highly selective oral inhibitor of the Ataxia telangiectasia and Rad3 related (ATR) kinase, which is required for efficient end-joining repair of double-stranded breaks, particularly during DNA replication. Many pediatric cancers involve potential ATR susceptibilities such as increased replication stress due to oncogenic fusions, specific DNA damage repair (DDR) deficiencies, oncogenic activation of DNA damage and nucleases such as PGBD5, as well as alternative lengthening of telomeres. We report the initial phase 1 results of PEPN2112 (NCT05071209), an ongoing pediatric phase 1/2 clinical trial of elimusertib monotherapy. Methods: Eligible patients (pts) included children, adolescents, and young adults with relapsed or refractory tumors with: (1) Ewing sarcoma or related EWSR1 fusion positive tumors (EWS), (2) alveolar rhabdomyosarcoma, PAX3-FOXO1 fusion positive (aRMS), or (3) non-CNS primary tumors exhibiting specific DDR pathway defects anticipated to sensitize to ATR inhibition. For pts < 18 years (yrs), a rolling-six design was used to evaluate elimusertib administered BID x3 days/week of a 28-day cycle starting at the adult equivalent recommended phase 2 dose (RP2D) of 24 mg/m2/dose (max 40 mg) with a potential de-escalation to 18 mg/m2/dose (max 30 mg). The pediatric RP2D determination was based upon dose limiting toxicity (DLT) criteria (CTCAEv5) during cycle 1. Pharmacokinetic (PK) studies were performed. Pts > 18 yrs could enroll onto the phase 2 cohorts at the adult RP2D simultaneously with the pediatric phase 1. Once the pediatric RP2D was defined, pts < 18 yrs accrued to the phase 2 cohorts and a PK expansion for pts < 12 yrs was opened. Results: 8 eligible pts were enrolled (4 males) on the phase 1 part of the study. 2 pts were inevaluable for DLT as they received < 75% of protocol therapy. Median (range) age was 13 (10-17) yrs. Diagnoses included: EWS (n = 4) and 1 pt each with aRMS, adrenocortical carcinoma, clear cell sarcoma, and osteosarcoma. At 24 mg/m2/dose, no DLTs were observed. Toxicities were hematologic, with grade 3 toxicities including anemia (n = 3), neutropenia (n = 4), and decreased white blood cells (n = 1). One pt experienced grade 4 lymphopenia. There were no grade 3/4 non-hematologic toxicities. Day 1 mean ± SD values of Tmax, Cmax, AUC0-8h and t1/2 were 1.6 ± 0.5 h, 1532 ± 385 ng/mL, 5863 ± 1841 h*ng/mL and 3.6 ± 0.9 h, respectively. Conclusions: Elimusertib-related toxicities were primarily hematologic. The RP2D for elimusertib monotherapy in pediatric pts is 24 mg/m2/dose (max 40 mg) orally BID x3 days/week continuously, analogous to dosing in adults with similar PK. Phase 2 and PK expansion cohorts as well as pharmacodynamic studies are ongoing. Clinical trial information: NCT05071209 .