PURPOSE:MEDI1191 is a lipid nanoparticle-formulated mRNA designed to induce local interleukin-12 production and intensify antitumor T cell responses. We report dose-escalation results from a first-in-human, open-label, phase I study of intratumoral MEDI1191 plus intravenous durvalumab (NCT03946800). METHODS:Patients were ≥18 years with advanced/metastatic solid tumors and had progressed on ≥1 line of prior therapy (immunotherapy permitted). Cutaneous/subcutaneous (Parts 1A and 1B) or deep-seated lesions (Part 1D) were injected; patients had ≥1 noninjected lesions measurable per RECIST v1.1. Target lesions were noninjected. MEDI1191 and durvalumab were given sequentially (Part 1A) or concurrently (Parts 1B and 1D). Primary objectives were safety and determination of maximum tolerated dose (MTD). Secondary objectives included efficacy. RESULTS:As of February 27, 2023, 61 patients were treated. Patients had a median of 4 prior regimens (range, 1-17); 39 (63.9%) received prior anti-PD-(L)1 immunotherapy. Treatment-emergent adverse events (TEAEs) occurred in 96.7% of patients and 41.0% experienced Grade 3/4 TEAEs. There were no dose-limiting toxicities. The MTD was not reached. Objective response rate was 9.8%, including 1 confirmed complete response and 5 confirmed partial responses (PRs). Duration of response was 2.7-22.3 months; median was not reached. Responses occurred in injected lesions, local noninjected lesions, and distant lesions. Three of the 39 patients with prior anti-PD-(L)1 therapy had PRs. CONCLUSIONS:MEDI1191 and durvalumab were tolerated. Preliminary antitumor activity was encouraging in these heavily pretreated patients, including patients previously treated with immune checkpoint inhibitors.

2634 Background: Checkpoint blockade achieves durable long term responses in about 30-50% of patients with malignant melanoma (MM). However, a substantial proportion of patients either fail to respond or develop resistance after initial response. As a result, many MM patients undergo multiple sequential immunotherapeutic treatments in an attempt to achieve clinical benefit. However, the effects of repeated rounds of immunotherapy on the immune system remain poorly understood. We herein report that prior anti-CTLA-4 blockade within 12 months of analysis associated with a hyperactive immunosuppressive immune signature involving IL-6, in 24 patients with anti-PD-1 refractory metastatic MM enrolled in a Phase I/II trial. Methods: The patients received continued checkpoint inhibition with an anti-PD-L1 antibody in combination with an immunostimulatory gene therapy based on replication-competent adenovirus targeting the CD40 and 4-1BB pathways (LOKON003, NCT04123470). Using unsupervised clustering, plasma biomarker profiles at baseline and post treatment initiation was evaluated and correlated to clinical parameters. Results: Two plasma protein profiles were identified at baseline among enrolled patients and one of those included immunosuppressive biomarkers. While patients with this hyperactive immunosuppressive signature (n=8) at baseline experienced a median overall survival (mOS) of 4.0 months, patients without this baseline signature (n=15) had a mOS of 28.1 months. The hyperactive immunosuppressive signature was not related to M1 status, sex, age, or number of prior treatments, but prior anti-CTLA-4 treatment within a year of enrollment was more prevalent in patients with this signature. If dividing the patients only based on receiving anti-CTLA-4 therapy within 12 months (n=10) versus later or not at all (n=14), mOS was 5.3 and 30.7 months, respectively. Patients that had received recent anti-CTLA-4 treatment, presented with a plasma protein signature resembling the hyperactive immunosuppressive signature with IL-6 as a central node among the upregulated proteins. Patients who did not receive anti-CTLA-4 blockade during the past 12 months responded to the combination of the immunostimulatory gene therapy and continued checkpoint blockade with upregulation of biomarkers associated with T cell activation and cell killing capacity, which may have supported the better survival outcome in this patient group. Conclusions: The findings highlight the need for further clinical evaluation of the consequences of repeated immunotherapeutic treatments, IL-6 inhibition in this population, and consideration for a wash-out period from further immunotherapy to allow for immune system recovery post anti-CTLA-4 treatment. Clinical trial information: NCT04123470 .

Abstract Introduction: IGSF8 (Immunoglobulin superfamily member 8) is a novel immune checkpoint that regulates both natural killer (NK) cell cytotoxicity and dendritic cell (DC)-mediated antigen presentation. GV20-0251, an artificial intelligence-designed antibody targeting IGSF8, is being evaluated in a Phase 1/2a clinical trial (NCT05669430) for metastatic solid tumors. Here, we report pharmacodynamic evaluation and potential predictive biomarkers from the monotherapy dose-escalation cohort. Methods: Target engagement and modulation were measured by flow cytometry on circulating CD3+ T cells. Pre- and on-treatment tumor tissues were assessed for IGSF8 expression and immune regulation by immunohistochemistry (IHC) and RNA-seq. IGSF8 expression in human tumors was examined using RNA-seq data from The Cancer Genome Atlas (TCGA) and IHC on tumor microarrays. Clinical response was evaluated per RECIST v1.1. Results: Forty-two participants were enrolled in this first-in-human monotherapy dose-escalation study. Among 16 evaluable cutaneous melanoma patients who had relapsed following prior anti-PD-1 treatment, three confirmed partial responses were observed. Target occupancy analysis demonstrated saturated IGSF8 binding by GV20-0251 on circulating T cells at doses ≥3 mg/kg. Treatment resulted in rapid reduction of IGSF8 cell surface expression on both circulating T cells and malignant cells within tumor tissues. IHC analysis of five paired tumor biopsies showed increased intratumoral infiltration of CD56+ NK cells and CD8+ T cells following treatment. RNA-seq of four paired melanoma tissues revealed immune cell infiltration, antigen presentation, and NK cytotoxicity as the top upregulated pathways post-treatment. Analysis of pretreatment tumors (n=10) revealed that patients achieving clinical benefit (partial response or stable disease) had higher IGSF8 RNA and membrane protein expression. In contrast, no objective response was observed in tumors with low or absent IGSF8 expression. TCGA database analysis demonstrated significant IGSF8 upregulation across multiple tumor types, including melanoma, hepatocellular carcinoma, and lung cancer. IHC examination of tissue microarrays further confirmed high IGSF8 positivity in these tumor types, all of which present high unmet medical needs. Conclusion: Pharmacodynamic analyses confirmed complete target occupancy at pharmacologically active doses with robust target modulation, leading to enhanced antigen presentation coupled with NK and CD8+ T cell infiltration. Preliminary data suggest a relationship between IGSF8 expression on cancer cells and clinical benefit, warranting further investigation. Collectively, these results provide proof-of-mechanism for GV20-0251 as a novel cancer immunotherapy and establish a potential biomarker strategy for further clinical development. Citation Format: Xingfeng Bao, Caibin Sheng, Inderjit Mehmi, Julio A. Peguero, Shivaani Kummar, Patricia LoRusso, Janice M. Mehnert, Aung Naing, Alexander I. Spira, Justin F. Gainor, Omid Hamid, Justin T. Moyers, Jin Wang, Xihao Wu, Hong Xiao, X. Shirley Liu, Tengfei Xiao, Kristopher Wentzel. Evaluation of pharmacodynamic and potential predictive biomarkers for GV20-0251, an anti-IGSF8 antibody, as monotherapy from ongoing Phase 1/2a study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr CT001.

TTFields have current FDA approval in GBM, NSCLC, and MPM that is refractory to frontline therapies. TTFields have also been shown to induce immunogenic cell death in vitro. Given the limited benefit of IpiNivo in mUM, we performed a signal seeking study of TTFields with IpiNivo in patients with refractory mUM. Patients with liver predominant mUM were treated with standard Ipi3Nivo1 dosing. After the first infusion, TTField arrays were placed for direct hepatic treatment with 200kHZ of alternating electric fields using the NovoTTF-200(O) device (>/= 18 hours daily); with imaging every 12 weeks for efficacy assessment. Fresh tissue and blood samples were collected for correlative work. 10 patients were enrolled. Patients were predominately Male (60%) with an ECOG of 0 (70%) and a median age of 60 and LDH of 575. The average number of prior lines of therapy was 1.5 with 70% of patients having prior checkpoint inhibitors (50% prior IpiNivo). Treatment was tolerated well with expected toxicity from IpiNivo. Rash due to TTFields was seen in 50% of patients with maximum severity of grade 2. A single partial response (10% ORR) was noted in one patient who had 5 prior lines of therapy, including IpiNivo without prior benefit. Four of five patients evaluable for ctDNA had at least a 0.5 log reduction with treatment, with one patient having full clearance of ctDNA. Median PFS and OS were 2.0 and 10 months for all patients. A PFS of 21 months was seen in one patient, who had previously progressed on two prior lines of therapy including immune checkpoint inhibitor and elected to come off study treatment after 1 cycle due to side effects from IpiNivo. Higher baseline peripheral interferon gamma levels were seen in patients who had PR or SD on imaging, while higher osteopontin levels were seen in patients who had PD. Following treatment, increases in macrophage and T-cell proportions were seen in two of the three patients with paired biopsy samples. Longer PFS was also seen in these patients. Additionally, increase in metabolic enzyme expression for mitochondrial metabolism and a corresponding decrease in glycolytic enzyme expression in macrophages and T-cells was seen after treatment. Overall, signs of clinical benefit from TTFields with IpiNivo were seen in this refractory and high disease burden patient population without signs of unexpected toxicity. Spatial transcriptomic data will be presented in the full presentation. Justin C. Moser, Joseph Lownik, Michael Gordon, Daniel Mocan, Chase Venable, Villamejor Anton, Ying Li, Sunil Sharma, Alexis Larsen, Justin Moyers, Omid Hamid, Akil Merchant, Inderjit Mehmi. Single Arm Pilot Study of Tumor Treating Fields (TTFields) with Nivolumab and Ipilimumab (IpiNivo) in Patients with Metastatic Uveal Melanoma (mUM) [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr A026.

Tebentafusp (IMCgp100, Kimmtrak) is a first-in-class Immune mobilizing monoclonal T-cell receptors against cancer (ImmTAC). ImmTAC are fusion proteins comprising an affinity-enhanced soluble T-cell receptor (TCR) against a specific peptide-HLA complex and an anti-CD3 single-chain variable fragment (scFv). Tebentafusp binds gp100(280-288) peptide from the melanocyte lineage-specific protein Glycoprotein 100 presented by HLA-A*02:01; concurrently, it engages CD3 on polyclonal T-cells leading to T-cell activation, and melanoma cell lysis. In the phase III IMCgp100-202 trial, tebentafusp significantly improved overall-survival versus investigator's choice, establishing it as a first-line treatment for HLA-A*02:01-positive advanced uveal melanoma. The safety profile is characterized by predictable on-target effects, mainly cytokine release syndrome and skin reactions, both diminishing over time. Tebentafusp validated ImmTAC as a novel class of TCR-based biologics targeting intracellular antigens. Ongoing research explores tebentafusp in other settings, including cutaneous melanoma. Other ImmTACs, e.g. brenetefusp is being developed, underscoring the potential of this modality in cancer immunotherapy.

Abstract Background: Assessing biomarkers to predict response is crucial for optimizing melanoma treatment with immune checkpoint inhibitors (ICIs). In this context, monitoring cytokine dynamics over time provides a rational strategy to determine whether IL-6R inhibition with sarilumab is biologically active and to identify pharmacodynamic signatures associated with clinical outcomes. Here, we focus on longitudinal serum cytokine profiling using Luminex assays to explore pharmacodynamic biomarkers for response in a phase II trial combining nivolumab (3 mg/kg), ipilimumab (1 mg/kg), the IL-6 receptor inhibitor sarilumab (150 mg), and the LAG-3 antibody relatlimab (160 mg) (INR + S) in patients with unresectable or advanced melanoma. Methods: We analyzed serum cytokines from 33 melanoma patients treated with INR + S using samples from baseline, week 4, week 6, week 12, week 18, and week 28 (final timepoint after discontinuation of sarilumab), and categorized patients according to response and toxicity. Patients were classified into PR/CR, SD, and PD groups, as well as grade 1-2 versus grade 3 or greater toxicity. Serum cytokines were profiled using Luminex assays, measuring 23 analytes. In total, 152 samples from 33 patients were analyzed. Statistical analyses were conducted using Mann-Whitney U test, paired t-test, and Kruskal-Wallis test, with the significance level set at 0.05. Results: The best overall response rate was 63.6%. Grade 3-5 irAEs occurred in 12% of patients by week 24. At baseline, no pretreatment predictive factors for either treatment response or > grade 3 irAEs were identified. Across all patients, several significant post-treatment patterns that correlated with clinical benefit were observed compared with baseline at one or more time points for IL-6, IL-6R, OSM, CXCL10, IL-4, IL-10, G-CSF, and M-CSF. Notably, PR/CR patients showed increased IL-6 and decreased IL-6R levels over time, which returned to baseline levels after discontinuation of sarilumab. When comparing baseline with week 4, progressive disease was associated with marked increases in OPN, and IL-8, whereas PR/CR patients showed decreases in IL-6R, IL-4, and G-CSF. Conclusion: Longitudinal analyses in the present study revealed increased IL-6 and decreased IL-6R levels. These dynamics likely reflect a more active mode of IL-6R blockade and may have contributed to improved clinical outcomes. The next phase of the trial is a randomized comparison of INR +/- S, and biospecimens from this randomized comparison will be analyzed to build on our findings. Citation Format: Teruyuki Mizutani, Amrutesh Puranik, Inderjit Mehmi, Judith Goldberg, Maya Dimitrova, Perla Arriola, Stanzin Idga, Xiaochun Li, Benjamin Levinson, Justine Cohen, Elizabeth I. Buchbinder, Donald Lawrence, Alissa Kalyan, Morgan Simons, F. Stephen Hodi, Ryan J. Sullivan, Omid Hamid, Michelle Krogsgaard, Janice M. Mehnert. Serum pharmacodynamic biomarkers of IPI/NIVO/RELA plus sarilumab in Stage III-IV melanoma: Stage 1 results of a Simon Phase II trial (NCT05428007) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6453.

Supplemental Figure 3: Decrease in Effector Tregs in Peripheral Blood in Patients Receiving BV+pembrolizumab

Supplemental Figure 5: Immune Response Pathway-related Gene Sets are Enriched in Responders as Compared to Non-responders in Baseline Tumor Biopsies

9510 Background: Combination immune checkpoint inhibitor regimens, especially those utilizing anti-CTLA-4 blockade, demonstrate higher response rates compared with single agent anti-PD-1 therapy but also increased rates of immune related adverse events (irAEs). IL-6, a key cytokine in driving inflammatory and autoimmune responses, is a compelling target to reduce irAEs through the use of IL-6 receptor (IL-6R) inhibitors. We conducted a clinical trial of 1L Nivo, Rela, and Ipi combined with the IL-6R inhibitor Sari in patients with advanced melanoma. Methods: 33 patients with advanced stage III/IV melanoma were treated in a single arm phase II trial. Patients received Nivo/Rela 480 mg/160 mg Q4W, Ipi 1 mg/kg Q8W and Sari 200mg q2 weeks for 12 doses over 24 weeks followed by maintenance Nivo/Rela 480 mg/160 mg Q4W and Ipi 1 mg/kg Q8W. Prior adjuvant immunotherapy was allowed if > 6 months before enrollment. Patients with controlled brain metastases could enroll. The co-primary endpoints were rate of grade (gr) 3-5 irAEs and antitumor activity defined by RECIST best overall response rate at 24 weeks. With 33 patients, a difference of ≥ 22% from the known irAE rate of Nivo, Rela, and Ipi could be detected using a binomial test (2-sided alpha = 0.05, 80% power). BORR was estimated with an exact 95% Clopper Pearson confidence interval. Circulating IL-6 signaling mediators were measured over time in 14 patients using Luminex assays. Results: 33 patients (40% F, 60% M, PS 0-1, median age 63) were treated. Median follow-up was 9.8 months (95% CI: 8.5, 12.6 months; data lock, 12/12/24). 3% had acral and 9% mucosal melanoma. 24% had > M1c disease and 39% elevated LDH. BRAF status, known for 81% of patients, was positive in 26%. BORR at 24 weeks was 63.6% (95% CI: 45.1%, 79.6%). Median PFS and OS were not reached (25 th percentile for PFS = 8.3 (95% CI: 2.77, NA) months). Median treatment duration was 28 weeks and 9% discontinued therapy for toxicity. At 24 weeks 12.1% (n = 4) experienced > gr 3/4 irAEs, significantly lower than the expected known irAE rate (2-sided p = 0.0007, 95% CI: 12.1%-28.2%). 27% (n = 9) had gr 3/4 toxicity over study duration; 93.9% (n = 31) had any grade irAE. Circulating IL-6Ra and IL-4 were significantly reduced at Cycle 2 (P < 0.05). Conclusions: Nivo, Rela, Ipi, + Sari demonstrated encouraging efficacy and tolerability. At 24 weeks, 63.6% BORR and 12.1% gr 3/4 irAE rate were observed. 2 patients had gr 4 toxicity; no gr 5 events were reported. These results compare favorably with published combination regimens including CTLA-4 blockade. Decreases in lL-6Ra and the inflammatory marker IL-4 observed post-treatment will be evaluted in a larger cohort of samples. An ongoing randomized cohort of Nivo + Rela + Ipi +/- Sari will further define the impact of IL-6R blockade on clinical outcomes in metastatic melanoma. Clinical trial information: NCT05428007 .

BACKGROUND:New treatment options are needed for patients with metastatic anti-programmed cell death 1 (PD-1)-resistant melanoma. The final analysis of a phase 1b study evaluating the Toll-like receptor 9 agonist vidutolimod is reported here. METHODS:This two-part, open-label, multicenter, phase 1b study in adults with metastatic/unresectable anti-PD-1-resistant melanoma evaluated the safety and clinical activity of intratumoral vidutolimod plus systemic pembrolizumab (part 1) or vidutolimod alone (part 2). Two vidutolimod formulations were evaluated with different concentrations of polysorbate (PS20-A, 0.005%-0.01% polysorbate 20; PS20-B, 0.00167% polysorbate 20). Key end points were safety and investigator-assessed objective response rate (ORR; Response Evaluation Criteria in Solid Tumors, version 1.1). RESULTS:A total of 159 patients were treated in part 1 (PS20-A, n = 98; PS20-B, n = 61), and 40 patients were treated in part 2. Any-grade treatment-emergent adverse events (TEAEs) occurred in 100.0% of patients. Grade ≥3 TEAEs occurred in 55.3% (part 1) and 37.5% (part 2) of patients. No treatment-related deaths occurred. Best ORR was 23.5% (95% CI, 15.5%-33.1%; complete response [CR], 7.1%) for vidutolimod PS20-A plus pembrolizumab, 11.5% (95% CI, 4.7%-22.2%; CR, 1.6%) for vidutolimod PS20-B plus pembrolizumab, and 20.0% (95% CI, 9.1%-35.6%) for vidutolimod monotherapy. Median duration of response was 25.2 months with vidutolimod PS20-A plus pembrolizumab, 11.4 months with vidutolimod PS20-B plus pembrolizumab, and 5.6 months with vidutolimod monotherapy. CONCLUSIONS:Vidutolimod PS20-A alone or in combination with pembrolizumab had an acceptable safety profile and promising clinical activity in patients with PD-1 blockade-resistant melanoma.

Neoadjuvant immunotherapies have shown antitumor activity in melanoma. Substudy 02C of the global, rolling-arm, phase 1/2, adaptive-design KEYMAKER-U02 trial is evaluating neoadjuvant pembrolizumab (anti-PD-1) alone or in combination, followed by adjuvant pembrolizumab, for stage IIIB-D melanoma. Here we report results from the first three arms: pembrolizumab plus vibostolimab (anti-TIGIT), pembrolizumab plus gebasaxturev (coxsackievirus A21) and pembrolizumab monotherapy. Pathologic complete responses occurred in 10 of 26 patients (38%) with pembrolizumab plus vibostolimab, 7 of 25 (28%) with pembrolizumab plus gebasaxturev and 6 of 15 (40%) with pembrolizumab monotherapy. Major pathologic responses occurred in 13 (50%), 10 (40%) and 7 (47%) patients, respectively. Safety was manageable. Treatment-related adverse events occurred in 24 of 26 patients (92%) with pembrolizumab plus vibostolimab, 21 of 25 (84%) with pembrolizumab plus gebasaxturev and 12 of 15 (80%) with pembrolizumab monotherapy; grade 3 or 4 treatment-related adverse events occurred in 2 (8%), 7 (28%) and 1 (7%) patient in each arm, respectively. No deaths due to adverse events occurred. Exploratory objective responses per RECIST v1.1 were observed in 13 (50%), 8 (32%) and 4 (27%) patients, in each arm, respectively. In a post hoc analysis, scores for tumor mutational burden and an 18-gene T cell-inflamed gene expression profile were generally higher in patients with major pathologic response. Longer follow-up will provide insight into the incremental benefit of combining neoadjuvant pembrolizumab with other therapies in stage IIIB-D melanoma. ClinicalTrials.gov registration: NCT04303169 .

Supplemental Figure 4: Percent of FOXP3+ cells out of total immune cells in tumor biopsies before and during treatment.

BACKGROUND/OBJECTIVES:Uveal melanoma is a rare but aggressive intraocular malignancy that metastasizes in up to half of patients, most commonly to the liver, despite effective local treatment. In the absence of robust evidence, there are no standardized guidelines for post-treatment surveillance, resulting in wide variation in imaging modalities, frequency, and duration across physicians and institutions. This study aimed to develop expert consensus recommendations for surveillance strategies in patients with uveal melanoma. METHODS:A modified Delphi method was conducted across three iterative survey rounds between September 2024 and February 2025 using an online platform. Panelists included medical oncologists, ocular oncologists, radiologists, and surgical oncologists from North America. A multidisciplinary steering committee developed statements addressing risk-based surveillance using both molecular and clinical prognostic factors, including gene expression profiling (GEP) and PRAME status. Consensus was defined a priori as ≥70% of panelists rating a statement 7-9 on a 9-point Likert scale. RESULTS:Forty-nine experts were invited, and 41 completed at least one survey round. The panel represented 17 U.S. states, Washington, D.C., and two Canadian provinces. Twelve statements reached stable consensus, including recommendations for imaging modality, frequency, and duration in intermediate- and high-risk patients. Although there was agreement that low-risk patients warrant surveillance, no consensus was reached on the optimal approach for this group. CONCLUSIONS:This is the first study to provide consensus-based guidance incorporating GEP and PRAME status into surveillance recommendations for uveal melanoma, offering a standardized framework to guide clinical practice and future research.

Background: Commercially available CTLA-4 antibodies are associated with a high incidence of immune mediated adverse events. Evalstotug (BA3071) is a conditionally active biologic (CAB) anti–CTLA-4 monoclonal antibody that blocks the interaction of CTLA-4 with its ligands in the low-pH conditions of the tumor microenvironment. CABs are not masked or caged and do not require enzymatic cleavage for activation. They are reversibly bound in the acidic tumor microenvironment, which is expected to reduce off-tumor immune-related adverse events, enhance host immunity, avoid tissue-mediated drug disposition, and improve pharmacokinetics. This study evaluated the safety and antitumor activity of evalstotug ± anti-PD-1 therapy in patients (pts) with advanced solid tumors. Methods: In an ongoing cohort for adult 1st line pts, treatment naïve unresectable/metastatic melanoma with measurable disease per RECIST v1.1 received evalstotug (350 – 1000 mg) every 3 weeks (Q3W) + pembrolizumab 200 mg Q3W. Safety was assessed using the NCI CTCAE v5, and efficacy was assessed using RECIST v1.1, with response assessment performed Q6W for 24 weeks, then Q12W. Results: An initial eight pts were treated with evalstotug (350-1000 mg) + anti-PD-1. Seven patients received prior neoadjuvant/adjuvant immunotherapy. Pts received a median of 9 doses. Most related treatment-emergent adverse events (TEAEs) were low grade. Two pts experienced grade 3 related TEAEs (1. colitis and 2. pneumonitis and pancreatitis) that led to discontinuation of treatment, but which quickly resolved. No grade 4/5 related TEAEs were observed to date. All patients experienced tumor volume reduction and those who were dose escalated were able to regain tumor control. Four of 8 pts responded - 3 PRs, 1 CR and 4 pts experienced stable disease. Conclusions: All (8/8) metastatic and unresectable melanoma pts safely achieved tumor reduction with evalstotug + anti-PD-1, including patients with only 1 scan, which will be further updated. It was notable that intrapatient evalstotug dose escalation safely re-attained tumor control, suggesting increasing evalstotug exposure can drive improved antitumor activity, even after months on anti-CTLA4 therapy. No new safety signals were identified, and the incidence and severity of imAEs was in line with previous reports, consistent with evalstotug’s tumor selectivity. Dose optimization is actively underway, and pivotal trial initiation is anticipated in 2025. Citation Format: Inderjit Mehmi, Jennifer E Selfridge, Ankit Mangla, Matthew H Taylor, Constantine Albany, Vineet Kwatra, Jacob Thomas, Siwen Hu-Lieskovan, Kyechin Chen, Judith Llorin-Sangalang, Kartik Aysola, Omid Hamid. Updated results from a study of evalstotug (BA3071), an anti–CTLA-4 conditionally active biologic, in melanoma [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A107.

Supplemental Table 1: Summary of Disposition

Abstract Purpose: Brentuximab vedotin (BV) is hypothesized to selectively deplete T regulatory cells that express CD30 and resensitize tumors to anti–PD-1 therapy. This study evaluated responses to BV + pembrolizumab after PD-1 therapy and explored corresponding biomarkers. Patients and Methods: A total of 55 patients with metastatic non–small cell lung cancer and 58 patients with metastatic cutaneous melanoma received ≥1 dose of BV + pembrolizumab. Patients had received a median of 2.0 prior lines of systemic therapies (range, 1–7). The primary endpoint was confirmed objective response rate (ORR). Exploratory endpoints included overall survival (OS) and biomarker analysis in blood and tumor. Results: For the secondary refractory metastatic non–small cell lung cancer cohort (RECIST v1.1), the ORR was 14%, median progression-free survival (PFS) was 5.85 months, and median OS was 14.4 months. For the secondary refractory metastatic cutaneous melanoma cohort (immune RECIST), the ORR was 24%, median PFS was 4.44 months, and median OS was 21.9 months. Overall, the median duration of OS follow-up was 17.2 months (95% confidence interval, 14.62–22.87). No new safety signals were identified. No treatment-related grade 5 toxicity was seen. Longitudinal immune phenotyping in peripheral blood demonstrated a transient decrease in T regulatory cells. Paired tumor biopsies from baseline and cycle 3 day 1 showed a trend of increased CD8 T-cell infiltration, especially in responding patients. Conclusions: BV + pembrolizumab in solid tumor malignancies resulted in clinically meaningful, durable responses with encouraging OS and PFS rates supportive of the immunomodulatory activity of this combination. Stronger antitumor activity was observed in secondary refractory cohorts. The safety profile of this combination was consistent with the individual drug risk profiles.

Cancer patients experience immune dysfunction due to both cancer and its treatment. Immune dysfunction leads to impaired responses to infections and vaccinations and may compromise immune-based anti-cancer therapies (Dai et al. 2020, Figueiredo et al. 2021, Cortes et al. 2022, Gagelmann et al. 2022). In previous work on cancer patients treated with SARS-CoV-2 vaccines, we identified phenotypic states of T cells prior to vaccination that are associated with humoral and cellular immune responses (Kazerani et al., ASH 2024). A limitation of this prior work was that T cells were characterized by immunophenotype and TCR repertoire, which does not provide direct functional assessment. To address this gap, we performed a longitudinal analysis of T-cell function in cancer patients using the activation-induced marker (AIM) assay to test T-cell function and correlated this to various clinical and oncologic outcomes. Our goal in this study is to define immune fitness in cancer patients as a prognostic and predictive biomarker. As part of the NCI SeroNet study, we have collected clinical data and blood samples from over 1,500 patients with cancer receiving primarily immune-based anti-cancer treatments and have reported their SARS-CoV-2 cellular and humoral responses (Figueiredo et al. 2021, 2024). Here, we performed a high-dimensional spectral flow cytometry-based AIM assay on PBMC samples collected from patients at multiple time points. Cells were stimulated with SARS-CoV-2 spike, nucleocapsid peptide megapools (both kindly provided by Daniela Weiskopf's team), control peptide pools (CMV, Flu, EBV, etc.), and DMSO (negative control) for 18-20 hrs (Antunes et al. 2023). Using a 26-marker immunophenotyping panel, unsupervised clustering identified 31 immune cell clusters, including 9 distinct T-cell subsets. Each AIM marker (CD69, 4-1BB, OX40, and CD40L) was DMSO subtracted, and AIM+ cells were defined using a Boolean strategy (Lemieux et al. 2024) with cells expressing 2 markers being considered AIM+, and we reported both relative and absolute numbers of AIM+ cells. In total, we analyzed 2563 samples from 815 patients for 338 million cell events. We integrated AIM data with prior TCR sequencing and serologic measurements of spike-specific antibodies. Active treatment was defined as any therapy being initiated or concluded within 6 months of vaccination (or within 3 months for immune checkpoint inhibitors). The distribution of malignancy types significantly differed between AIM responders and non-responders. Notably, patients with hematologic malignancies exhibited significantly higher frequencies of both AIM+ CD4+ (P < 0.001) and CD8+ T cells (P < 0.001), as well as a trend toward higher absolute counts of AIM+ CD4+ T cells, compared to patients with solid tumors. Longitudinal monitoring further confirmed sustained and superior T-cell activity in the hematologic malignancy cohort. Given the inferior longitudinal humoral response in patients with hematologic malignancies (Figueiredo et al. 2021), our data support the notion that virus-specific T cells may compensate lack of B-cell immunity in patients with lymphoma or myeloma receiving B-cell depleting therapies (Liebers et al., Enßle et al., Blood 2022). Conversely, patients with solid tumors demonstrated impaired T-cell activity despite showing comparable humoral responses to healthy individuals. Furthermore, in 41% of AIM+ patients, no Spike-specific TCRs were detected, highlighting the limitation of TCR sequencing in capturing unique or non-public T-cell clones. In contrast, 64% of AIM– patients had detectable Spike-specific TCRs, implying potential T-cell dysfunction. Many of these patients had solid tumors, and 50% of them also showed no response to control peptide stimulation, indicating a broader state of T-cell unresponsiveness. Finally, survival analysis revealed that patients who were AIM+ in response to control peptide stimulation exhibited better survival than AIM– patients (P = 0.04), suggesting the clinical significance of T-cell immune competence. Our large-scale functional profiling provides valuable insights into T-cell fitness in cancer patients. Ongoing work aims to expand the dataset and characterize T-cell subsets and immune populations influencing T-cell function. These findings underscore the clinical relevance of T-cell functionality as a surrogate for immune fitness to inform personalized immunotherapeutic strategies.

Background: In BRAF-mutated high-risk melanoma, targeted therapy (BRAF/MEK inhibitors) and checkpoint inhibitor (CPI) immunotherapy have durable benefits as first-line (1L) adjuvant therapy. Based on differing action mechanisms of BRAF/MEK inhibitors and CPI immunotherapies, there is interest in evaluating the activity of 2L adjuvant targeted therapy in decreasing the risk of subsequent recurrence after repeat resection following relapse on/after 1L adjuvant CPI. Patients and methods: This was a retrospective review of BRAF V600-mutated resected stage III/IV melanoma patients in the United States, Australia, and The Netherlands who received 1L adjuvant CPI immunotherapy, relapsed locoregionally/distantly, were again resected to no evidence of disease, and received dabrafenib/trametinib (dab/tram) as 2L adjuvant therapy. The primary endpoint was relapse-free survival (RFS) from initiation of 2L adjuvant dab/tram (RFS-2), analyzed via Kaplan-Meier methods. Results: Thirty-eight patients were included (median age 50 years, 63% male, 87% stage III, median follow-up 19 months from 2L dab/tram initiation). Median dab/tram duration was 10.1 months (range: 1 day-22.7 months), with half discontinuing due to progression or adverse events. Median (95% CI) RFS-2 was 18.9 (14.9-28.1) months, with 91%, 81%, and 58% remaining relapse-free at 6, 12, and 18 months, respectively. Most patients remained distant metastasis-free at 6, 12, and 18 months (97%, 85%, and 71%, respectively).Two patients were deceased at the last follow-up, with 97% alive at 18 months. Conclusions: Over 80% of patients remained relapse- and metastasis-free at 12 months after 2L dab/tram initiation, with only 2 deaths observed. Dab/tram appears to have activity in the 2L adjuvant setting, although more follow-up is required.