Cohen, Justine Vanessa

9508 Background: Outcomes for pts with mMEL remain sobering despite access to available immunotherapies as the majority of pts are resistant or become refractory to checkpoint blockade with no approved treatments. CXCR1 and CXCR2 (CXCR1/2) signaling mediate myeloid immunosuppression and MEL growth, inversely correlating with anti-PD-1 response and pt survival. SX-682 is an oral allosteric inhibitor of CXCR1/2. As a single agent, SX-682 increases tumor CD8+ T cell infiltration and inhibits tumor growth in mouse MEL. Methods: This phase 1 dose-escalation with expansion trial (NCT03161431) evaluated pem and escalating doses of SX-682 (25 - 400 mg orally BID) in pts with mMEL in a 21-day cycle. Pts must have had progressive disease (PD) on prior anti-PD-1. Mucosal MEL and asymptomatic brain metastases were allowed. Escalation cohorts had a 21-day SX-682 monotherapy (MONO) run-in. Response assessment by RECIST 1.1 was every 2 cycles during combination (COMBO) treatment. Primary endpoint was safety: adverse events (AEs), dose-limiting toxicity (DLT) and maximally-tolerated dose (MTD). Secondary endpoints included objective response rate (ORR; complete [CR] + partial [PR] response), disease control rate (DCR; CR + PR + stable disease [SD]) and overall survival (OS). Results: As of October 2023, 51 pts were enrolled and treated; median age of 65 (range 24-91), 55% male, 61% elevated LDH, 39% BRAF mutated. All pts received prior anti-PD-1, 37 (73%) received combined anti-PD-1 and anti-CTLA-4, and 23 (45%) had ≥ 3 prior therapies. Steady-state blood SX-682 was dose-proportional. No MONO DLT or MTD was identified. The 200 mg dose cohort was expanded in COMBO based on safety and pharmacodynamics: mg BID dose (n) = 25 (3), 50 (3), 100 (6), 150 (8), 200 (31). Any grade and grade 3/4 treatment-related AEs (TRAEs) occurred in 75% and 43%, respectively, and discontinuation (DC) due to TRAEs in 20% (when uncomplicated neutropenia, a permitted effect from CXCR2 inhibition on bone-marrow trafficking, was excluded there were 25% grade 3/4 TRAEs and 12% DC [rash, transaminitis]). There was no infectious signal. At the 200 mg dose, the ORR was 21% in 19 evaluable pts (4 PR + 0 CR) and the DCR was 63% (8 SD + 4 PR). DCR significantly depended on SX-682 dose ( P vs. ≤100 mg): 0% (0/9) at ≤100 mg, 50% (3/6) at 150 mg ( P = 0.0440) and 63% (12/19) at 200 mg ( P = 0.0028). All 15 pts with disease control had progressed on anti-PD-1 and anti-CTLA-4. Median OS was longer in pts in the 200 mg cohort (14.7 months; 95% CI, 10.5 – NR [not reached], n = 31) than in pts treated with ≤100 mg SX-682 (7.4 months; 95% CI, 5.0 – NR; n = 10). Conclusions: SX-682 combined with pem had a tolerable safety profile and activity reflected by objective responses and clinically meaningful disease control in heavily pretreated mMEL pts with progression on anti-PD-1 and anti–CTLA-4. Clinical trial information: NCT03161431 .

Expanding the US Food and Drug Administration–approved indications for immune checkpoint inhibitors in patients with cancer has resulted in therapeutic success and immune-related adverse events (irAEs). Neurologic irAEs (irAE-Ns) have an incidence of 1%–12% and a high fatality rate relative to other irAEs. Lack of standardized disease definitions and accurate phenotyping leads to syndrome misclassification and impedes development of evidence-based treatments and translational research. The objective of this study was to develop consensus guidance for an approach to irAE-Ns including disease definitions and severity grading. A working group of four neurologists drafted irAE-N consensus guidance and definitions, which were reviewed by the multidisciplinary Neuro irAE Disease Definition Panel including oncologists and irAE experts. A modified Delphi consensus process was used, with two rounds of anonymous ratings by panelists and two meetings to discuss areas of controversy. Panelists rated content for usability, appropriateness and accuracy on 9-point scales in electronic surveys and provided free text comments. Aggregated survey responses were incorporated into revised definitions. Consensus was based on numeric ratings using the RAND/University of California Los Angeles (UCLA) Appropriateness Method with prespecified definitions. 27 panelists from 15 academic medical centers voted on a total of 53 rating scales (6 general guidance, 24 central and 18 peripheral nervous system disease definition components, 3 severity criteria and 2 clinical trial adjudication statements); of these, 77% (41/53) received first round consensus. After revisions, all items received second round consensus. Consensus definitions were achieved for seven core disorders: irMeningitis, irEncephalitis, irDemyelinating disease, irVasculitis, irNeuropathy, irNeuromuscular junction disorders and irMyopathy. For each disorder, six descriptors of diagnostic components are used: disease subtype, diagnostic certainty, severity, autoantibody association, exacerbation of pre-existing disease or de novo presentation, and presence or absence of concurrent irAE(s). These disease definitions standardize irAE-N classification. Diagnostic certainty is not always directly linked to certainty to treat as an irAE-N (ie, one might treat events in the probable or possible category). Given consensus on accuracy and usability from a representative panel group, we anticipate that the definitions will be used broadly across clinical and research settings.

TPS2573 Background: Brain metastases, most commonly derived from melanoma, lung and breast cancers, are the most common brain tumor, with approximately 200,000 cases diagnosed annually in the United States. Median survival is on the order of months. For patients with clinically symptomatic brain metastases, approximately half succumb due to intracranial progression. In preclinical work, we demonstrated that brain metastases and primary tumors are often genetically distinct with frequent alterations in the CDK and PI3K pathway (Brastianos, Carter et al. Cancer Discovery 2015). Methods: We are currently accruing to a prospective multi-arm phase II study of CDK, PI3K/mTOR, and NTRK/ROS1 inhibitors in patients with brain metastases harboring alterations associated with sensitivity to these inhibitors (abemaciclib, paxalisib and entrectinib), respectively. Patients with new, recurrent or progressive brain metastases are eligible for this trial. Previously obtained tissue from brain metastases and extracranial sites (primary or extracranial metastases) are screened for the presence of these alterations, and if present in both tumor sites, patients will receive the appropriate corresponding targeted treatment. Screening is carried out with the SNaPshot NGS assay, which is a fully validated clinical test designed and developed at the MGH Center for Integrated Diagnostics. The primary endpoint of response rate (RR) in the central nervous system as per RANO criteria will be evaluated separately for each inhibitor, stratified by histology within each arm. There will be 21 evaluable patients assigned to each of the CDK and PI3K inhibitor and tumor type cohorts (breast, lung and other) and 10 patients assigned to the NTRK/ROS1 inhibitor cohort (lung) for a total of 136 evaluable patients. Although current systemic therapy for brain metastases is often ineffective, we hypothesize that targeted therapies will demonstrate efficacy in patients harboring the appropriate mutations. This study represents a novel individualized therapeutic approach in brain metastases, a disease with a critical need for effective therapy. Support: U10CA180821, U10CA180882, https://acknowledgments.alliancefound.org ; Genentech, Kazia Therapeutics Limited, Eli Lilly; Clinical trial information: NCT03994796 .

Expanding use of immune‐checkpoint inhibitors (ICIs) underscores the importance of accurate diagnosis and timely management of neurological immune‐related adverse events (irAE‐N). We evaluate the real‐world frequency, phenotypes, co‐occurring immune‐related adverse events (irAEs), and long‐term outcomes of severe, grade III to V irAE‐N at a tertiary care center over 6 years. We analyze how our experience supports published literature and professional society guidelines. We also discuss these data with regard to common clinical scenarios, such as combination therapy, ICI rechallenge and risk of relapse of irAE‐N, and corticosteroid taper, which are not specifically addressed by current guidelines and/or have limited data. Recommendations for management and future irAE‐N reporting are outlined. ANN NEUROL 2020;87:659–669