Publications

e15134 Background: Sarcopenia, or skeletal muscle wasting, is an independent prognostic factor in advanced malignancy (Prado Lancet Onc 2008) . Decreased muscle and increased fat are recognized side effects of androgen deprivation therapy. AA is a CYP17 inhibitor administered with corticosteroids (C), approved for treatment of advanced CRPC. AA reduces circulating androgens to ‘super-castrate’ levels; we hypothesized that AA + C would impact body composition. Methods: We retrospectively evaluated 54 CRPC pts treated on a Phase I/II trial. Pts received AA alone followed by combination AA + C on biochemical progression. CT scans at baseline, on AA alone and on AA + C were analyzed. Cross-sectional areas of fat and muscle were measured on 3 consecutive images at L4 using OsiriX 4.0. Muscle area was used to calculate skeletal muscle index (SMI); sarcopenia was defined as SMI <52.4 cm 2 /m 2 . Data were analyzed using t-tests and Kaplan-Meier analysis with overall survival (OS) measured from day 1 of AA. Results: Median duration on AA alone was 7.4 months (m; range 1.4-37.5); median duration on concurrent AA + C was 7.4m (range 0.9-46.2). Body composition did not change between two pre-treatment scans (n=29; median 3m apart). On AA alone there was a decrease in total fat (-8.5%, p=0.0001), visceral fat (-9.8%, p=0.0015) and muscle mass (-3.9%, p=0.0023) with a significant decrease in mean body mass index (BMI; -3.4 %, p=0.0118). Conversely AA + C was associated with increased total fat (+15.1%, p<0.0001) and visceral fat (+21.4%, p<0.0001) but no further change in muscle mass. Mean BMI significantly increased on the addition of C, returning to baseline levels (p< 0.0001). Overall, 13 pts (24%) were sarcopenic prior to commencing AA compared to 22 (41%) at the end of treatment. Pts who were sarcopenic at baseline had significantly reduced OS: 26.1m (95%CI 16.6 – 41) vs 46.5m (95%CI 28.6 – 57.5, p=0.0253). Conclusions: Treatment with AA alone resulted in decreased fat and muscle. AA + C increased body fat without further alteration in muscle mass. Changes in BMI did not reflect changes in body composition. Sarcopenia at baseline was a negative prognostic factor in this population.

TPS9589 Background: The treatment of melanoma has improved markedly with the emergence of new immune therapies, and both anti-PD-1 monotherapy and the combination of the anti-PD-1 antibody nivolumab and anti-CTLA-4 therapy ipilimumab are now considered standard-of-care in the unresectable or metastatic (advanced) melanoma setting. However, many patients have primary or acquired resistance to these therapies, thereby underpinning the need for more effective approaches. IO102-IO103 is a potentially first-in-class, dual-antigen, immune-modulatory therapy targeting the key cancer immune resistance pathways mediated by IDO and PD-L1. The ability of IO102 and IO103 to respectively activate the specific T cells that recognize these checkpoint molecules and directly modulate immune regulation has previously been demonstrated both preclinically and in human clinical trials. A synergistic anti-tumor response upon treatment against both IDO and PD-L1 has also previously been demonstrated in a preclinical model where IDO and PD-L1 were expressed by different cells in the tumor microenvironment. Due to the distinctive mechanisms of action of IO102-IO103 and anti-PD-1 antibodies, there may be a further synergistic effect when treatment is combined. A previous Phase 1/2 trial investigating the use of IO102-IO103 plus nivolumab in patients with anti-PD-1-naïve metastatic melanoma has demonstrated promising anti-tumor activity with an overall response rate (ORR) of 80%, median progression-free survival (PFS) of 26 months and a manageable safety profile (NCT03047928; Kjeldsen et al, Nat Med 2021). Methods: This is a Phase 3, multicenter, open-label, randomized, 2-arm trial investigating the efficacy and safety of IO102-IO103 plus pembrolizumab versus pembrolizumab alone (EudraCT: 2021-004594-32; ClinicalTrials.gov No: NCT05155254). Inclusion criteria include: adult patients with untreated, unresectable (Stage III), or metastatic (Stage IV) melanoma; > 6 months since last dose of (neo)adjuvant treatment with targeted or immune therapy (in those previously treated); and ≥1 measurable lesion by RECIST v1.1. Primary endpoint is PFS by blinded independent central review. Secondary endpoints include ORR, durable response rate, complete response rate, duration of response, time to response, disease control rate, overall survival, and safety/tolerability. Target enrollment is 300 patients at > 100 sites in 20 countries. Patients are randomized 1:1 to receive either pembrolizumab 200 mg intravenously (IV) every 3 weeks up to 2 years or pembrolizumab 200 mg IV every 3 weeks up to 2 years with dual-antigen IO103-IO102 85-85 µg and Montanide adjuvant subcutaneously on Day 1 and 8 of cycle 1 and 2 and on Day 1 of each cycle thereafter. Enrolment for the study is ongoing. Clinical trial information: EudraCT: 2021-004594-32; ClinicalTrials.gov No: NCT05155254.

Background Prostate cancer (PCa) has a profoundly immunosuppressive microenvironment and is commonly immune excluded with few infiltrative lymphocytes and low levels of immune activation. High-dose radiation has been demonstrated to stimulate the immune system in various human solid tumors. We hypothesized that localized radiation therapy, in the form of high dose-rate brachytherapy (HDRBT), would overcome immune suppression in PCa. Methods To investigate whether HDRBT altered prostate immune context, we analyzed preradiation versus postradiation human tissue from a cohort of 24 patients with localized PCa that received HDRBT as primary treatment (RadBank cohort). We performed Nanostring immune gene expression profiling, digital spatial profiling, and high-throughput immune cell multiplex immunohistochemistry analysis. We also resolved tumor and nontumor zones in spatial and bioinformatic analyses to explore the immunological response. Results Nanostring immune profiling revealed numerous immune checkpoint molecules (eg, B7-H3, CTLA4, PDL1, and PDL2) and TGFβ levels were increased in response to HDRBT. We used a published 16-gene tumor inflammation signature (TIS) to divide tumors into distinct immune activation states (high: hot , intermediate and low: cold ) and showed that most localized PCa are cold tumors pre-HDRBT. Crucially, HDRBT converted 80% of these ‘cold’-phenotype tumors into an ‘intermediate’ or ‘hot’ class. We used digital spatial profiling to show these HDRBT-induced changes in prostate TIS scores were derived from the nontumor regions. Furthermore, these changes in TIS were also associated with pervasive changes in immune cell density and spatial relationships—in particular, between T cell subsets and antigen presenting cells. We identified an increased density of CD4 + FOXP3 + T cells, CD68 + macrophages and CD68 + CD11c + dendritic cells in response to HDRBT. The only subset change specific to tumor zones was PDL1 - macrophages. While these immune responses were heterogeneous, HDRBT induced significant changes in immune cell associations, including a gained T cell and HMWCK + PDL1 + interaction in tumor zones. Conclusion In conclusion, we showed HDRBT converted “cold” prostate tumors into more immunologically activated “hot” tissues, with accompanying spatially organized immune infiltrates and signaling changes. Understanding and potentially harnessing these changes will have widespread implications for the future treatment of localized PCa, including rational use of combination radio-immunotherapy.

9515 Background: Anti-PD1-antibodies (PD1) have activity in many cancers, and are standard care for melanoma, lung and renal cancer. All trials excluded patients (pts) with significant preexisting AD or major immune-related adverse events (irAEs) with IPI. We sought to explore the safety and efficacy of PD1 in such pts. Methods: Pts with advanced melanoma and preexisting AD and/or major irAEs with prior IPI (requiring systemic immunosuppression, [IS]) treated with PD1 were retrospectively identified. Data regarding AD, IPI and PD1 treatments, toxicity and outcome were examined. Results: 119 pts were included, 95 with prior IPI. 109 received pembrolizumab, 10 nivolumab. 86 (72%) had ≥ 3 months (mo) follow-up, median (med) 4.6 mo, with med PFS 6.8 mo. 31 (26%) had died. Of 52 pts with preexisting AD, 15 (29%) had active symptoms at PD1 start and 16 (31%) were on IS. The ORR was 33%. 20 (38%) flared with PD1 after a med 1.3 mo, including 7/13 with rheumatoid arthritis, 3/3 with polymyalgia rheumatica, 2/2 with Sjogren’s syndrome, 1/2 with scleroderma, 2/2 with immune thrombocytopaenic purpura, 3/8 with psoriasis, 1/4 with Graves’ disease, 0/6 with gastrointestinal (GI) (including 3 Crohn’s disease) and 0/5 with neurological disorders. 3 (6%) had grade (G) 3 flare, and 2 (4%) discontinued PD1 for flare. 15 (29%) developed other irAEs (5 G3), 3 (6%) discontinued PD1. 67 pts had irAEs requiring IS with prior IPI (9 G2, 51 G3, 7 G4), including 47 with ≥ G3 colitis (15 had infliximab), 2 with G4 hepatitis (1 had antithymocyte globulin), and 9 with hypophysitis. All irAEs except hypophysitis had resolved at PD1 start except in 1 pt (arthritis), 5 were on IS at PD1 start. The ORR was 40%. 2 (3%) had recurrence of IPI irAEs with PD1 (arthritis, colitis), but 23 (34%) developed new irAEs (13, 19% ≥ G3), and 11 (16%) discontinued PD1. There were no treatment related deaths. Conclusions: PD1 have efficacy in pts with preexisting AD and/or major irAEs with IPI. PD1 may flare preexisting AD, particularly rheumatologic, but GI and neurological disorders may flare less. In pts with prior major irAEs with IPI recurrence of the same irAE is rare, but new irAEs occur. The rate of irAEs in these pts appears higher than in clinical trial pts.

151 Background: ENZAMET randomized 1125 participants with mHSPC to compare enzalutamide (ENZA) versus a standard non-steroidal anti-androgen (NSAA) and demonstrated superior progression-free survival and overall survival (PFS and OS) with ENZA. Radiographic progression in the absence of prior/concurrent PSA progression (rProg1st) is an emerging biomarker of poor clinical outcomes. We sought to determine the frequency of rProg1st, and correlate the impact of enzalutamide on transitions between disease states for the ENZAMET cohort. Methods: The ENZAMET dataset was analyzed using a multi-state Cox proportional hazards regression model that partitioned the clinical experience of participants (pts) into 4 states: (1) Evt-Free (event-free), (2) rProg1st (radiologic progression recorded without prior/concurrent evidence of confirmed PSA progression), (3) OtherProg (All Other type of clinical progression events (PSA and treatment switch, excluding death), (4) Death. Results: Radiographic progression was recorded in 388/1125 (34%) pts. Radiographic progression without confirmed prior/concurrent PSA progression per protocol was recorded in 114/1125 (10%) with similar proportions in those assigned ENZA 55/114 (48%) vs NSAA 59/114 (52%). Baseline characteristics of the 114 pts with rProg1st were similar to the other pts in ENZAMET, and were similar in the ENZA and NSAA groups (Table 1). Compared with NSAA, ENZA delayed both rProg1st (HR 0.66, 95%CI: 0.46 to 0.96, p=0.03) and OtherProg (HR 0.37, 95%CI: 0.31 to 0.44, p<0.001). 5-year OS rates were 24% (95%CI: 18-34) in the rProg1st group versus 42% (95%CI: 38-47) in the OtherProg group. Of those who had not progressed (495/1125) with a median follow-up of 68 months, 8% had died of causes other than prostate cancer. As previously reported ENZA prolonged overall survival in the whole trial cohort (N=1125, HR 0·70, 95%CI 0·58 to 0·84, p<0·0001). Conclusions: Participants who had radiographic progression without prior/concurrent PSA progression had worse overall survival whether assigned NSAA or enzalutamide. Enzalutamide reduced the hazards for, and delayed the times to, rProg1st and OtherProg. There were no baseline characteristics that helped identify these pts upfront; we plan molecular biological analyses to help identify this unique group earlier. Clinical trial information: NCT02446405 . [Table: see text]

<p>Summary of tumor (baseline) and cfDNA (baseline and progression) mutations detected by WES for a patient who responded to Olaparib. New events in TP53 and TSC2 were detected at progression.</p>

Elevated ribosome biogenesis in oncogene-driven cancers is commonly targeted by DNA-damaging cytotoxic drugs. Our previous first-in-human trial of CX-5461, a novel, less genotoxic agent that specifically inhibits ribosome biogenesis via suppression of RNA polymerase I (Pol I) transcription, revealed single-agent efficacy in refractory blood cancers. Despite this clinical response, patients were not cured. In parallel, we demonstrated a marked improvement in the in vivo efficacy of CX-5461 in combination with PI3K/AKT/mTORC1 pathway inhibitors. Here, we reveal the molecular basis for this improved efficacy observed in vivo, which is associated with specific suppression of translation of mRNAs encoding regulators of cellular metabolism. Importantly, acquired resistance to this cotreatment is driven by translational rewiring that results in dysregulated cellular metabolism and induction of a cAMP-dependent pathway critical for the survival of blood cancers including lymphoma and acute myeloid leukemia. Our studies thus identify key molecular mechanisms underpinning the response of blood cancers to selective inhibition of ribosome biogenesis and define metabolic vulnerabilities that will facilitate the rational design of more effective regimens for Pol I-directed therapies.

LBA5004 Background: The first planned interim analysis of ENZAMET, with 243 deaths after a median follow-up of 34 months, revealed a clinically meaningful overall survival benefit in mHSPC with the addition of enzalutamide to standard of care (hazard ratio 0.67, 95% CI 0.52 to 0.86, p=0.002, Davis et al, NEJM 2019). We now present updated overall survival (OS) findings from the prespecified analysis triggered to occur after 470 deaths. Methods: We randomly assigned participants (pts) with mHSPC to treatment with testosterone suppression (TS) plus either a conventional non-steroidal anti-androgen (NSAA) or enzalutamide. Stratification factors included age, volume of disease (high vs low according to the CHAARTED definition), and planned use of concurrent docetaxel assigned by the treating physician (docetaxel yes vs no). Results: We randomized 1125 pts with a median age of 69 years, including 503 in the docetaxel stratum, and 602 with high volume metastatic disease. OS results in the table below are based on 476 deaths, a median follow-up of 68 months, and a cut-off date of 19JAN2022. The hazard rate for death was 30% lower among all those assigned enzalutamide versus control (p<0.0001). Outcomes by volume status are shown (Table) as well as the subgroups of interest with M1 high or low volume disease at diagnosis selected for concurrent docetaxel. Conclusions: Enzalutamide added to TS, compared with an active comparator of NSAA, provided clinically meaningful improvements in OS for the combined overall cohort, which persisted with an additional 3 years of follow-up. The benefits were more pronounced in pts with low volume disease, and were also seen in the subgroup with M1 high volume mHSPC despite the relatively high survival with TS+docetaxel+NSAA. ENZAMET was led by ANZUP Cancer Trials Group and the University of Sydney NHMRC Clinical Trials Centre, with funding support from Astellas. Clinical trial information: NCT02446405. [Table: see text]

Abstract INTRODUCTION: Immune checkpoint inhibitors (ICI) in metastatic melanoma results in durable responses in ∼50% of patients. Our understanding of the tumour immune microenvironment (TME) features underpinning ICI response or resistance is currently incomplete. METHODS: To address this issue, we explored the TME of melanoma lymph node metastases (MLN mets) at a spatial (n = 32) and a single cell level (n=24). MLN mets were either from ICI-responder and ICI-resistant patients or untreated controls. We used multiplex IHC and our SPIAT algorithm to examine the spatial immune context of the TME, and also analyzed gene expression by RNAseq. Cells were also isolated from fresh tissue before or after ICI and analyzed by single cell RNAseq and TCRseq to derive high dimension data on T cells and their clonality, all other immune and melanoma cells. Finally, we performed cell-cell interactome and neighborhood analyses to reveal which cell and molecular interactions were associated with response. RESULTS: In patients who responded to ICI, both CD4+ and CD8+ tissue resident memory (TRM) T cell subset density were significantly increased within the tumor, and this correlated with closer distance to melanoma cells. (p<0.05). Single cell data revealed multiple clusters of immune cells (T, B, NK, Mø, DC) and melanoma cells. CD8+ T cell clustering revealed heterogeneous differentiation states. In ICI responders, we observed enrichment for TRM with an earlier transcriptional profile (TCF1+ Tpex.TRM and early TEM.TRM) and lower expression of the exhausted T cell (Texh) gene signature (p<0.05). Hyperexpanded CD8+ T cell clones were present in the TRM cell cluster and were enriched in the responder patients but not in those with resistant disease. CD4+ T cells showed both TRM and TFH clusters with shared expression of multiple genes, with CD4+ TRM also expressed a cytotoxicity gene module. Additionally, Mø and melanoma cells in resistant disease had significantly higher IFNg and IFN-I response gene expression levels compared to tumors from responders (p<0.05), suggesting that chronic activation of T cells in LN mets could lead to the observed Texh phenotype. Interactome analysis displayed putative interactions between CD4+ and CD8+ TRM via the CCL4-CCR5 axis in the ICI responders. This was confirmed by spatial analysis of neighborhood archetypes, which showed significantly increased cell-cell contact between both TRM subsets within the tumor of responders (p<0.05). Finally, conventional dendritic cells interact with both CD8+ and CD4+ TRM subsets in the tumor of responders, providing key signals for maintenance of the TRM pool within the tumor. CONCLUSIONS: MLN mets that respond to ICI are characterized by increased TRM comprising hyperexpanded TCR clones and complex TRM-containing neighborhood archetypes. Whilst these tumors show increased global inflammation, at a single cell level the resistant tumors have increased Texh and greater expression of IFN-regulated genes in melanoma cells and macrophages suggesting ineffective response to chronic antigen stimulation. Citation Format: Andrea Di Pietro, Lewis Au, Patrick Crock, Niko Thio, Angela Pizzolla, Marina Bacac, Ramona Schlenker, Aparna Rao, L Spain, David Gyorki, Shahneen Sandhu, Grant McArthur, Paul J Neeson. Tissue resident memory (TRM) T cells and dendritic cells form an in situ archetype for improved response to immune checkpoint therapy in metastatic melanoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A006.