Baseline Biopsies Research Articles

Phase II study of enasidenib in IDH2-mutated malignant sinonasal and skull base tumors.

TPS3183 Background: Advanced sinonasal malignancies are rare and heterogeneous cancers with limited therapeutic options. Tumor types include olfactory neuroblastoma (ONB), sinonasal undifferentiated carcinoma (SNUC) and large cell neuroendocrine carcinoma (LCNEC), chondrosarcoma, and sinonasal adenocarcinoma (SNAC). Pathogenic driver mutations in isocitrate dehydrogenases 1 and 2 ( IDH1 and IDH2) were identified first in glioma and myeloid malignancies. IDH1/2 enzymatic activity catalyzes conversion of isocitrate and NADP+ to α-ketoglutarate (α-KG) and NAPDH, which are critical for cellular metabolism and for α-KG-dependent dioxygenases; mutant IDH1/2 catalyze conversion of α-KG to the oncometabolite 2-hydroxyglutarate (2-HG), a competitive antagonist of α-KG in regulating dioxygenases activity, with subsequent impact on DNA histone methylation and cellular differentiation. R172S or R172T IDH2mut have been detected in up to 80% of SNUCs and in a minority of ONB, chondrosarcoma, LCNEC and SNAC. Enasidenib is an oral small molecule inhibitor of the mutant IDH2 protein which prevents 2-HG accumulation and releases cancer cells from the differentiation block. It is currently approved for relapsed/refractory IDH2mut myeloid malignancies with proven clinical efficacy. Methods: This is a phase 2, single arm clinical trial conducted at the Center for Cancer Research (CCR) of the National Cancer Institute. The trial investigates the activity of enasidenib in adult patients with histologically or cytologically confirmed locally advanced or metastatic IDH2mut sinonasal cancers (SNUC, ONB, LCNEC, chondrosarcoma, SNAC). Participants must have RECIST 1.1 measurable disease and must have progressed following at least one prior systemic treatment line administered in the recurrent/metastatic setting; those with locally advanced disease must not be amenable to potentially curative approaches. Participants must also have ECOG performance status ≤ 2, be 18 years old or higher, and have adequate organ function. Participants with active, either new or progressive brain metastases or leptomeningeal disease are excluded. Enasidenib will be given continuously at a fixed dose of 100 mg orally daily in a 28-day cycle, until disease progression, unacceptable toxicity, or consent withdrawal. Imaging will be performed every 8 weeks. Baseline and on-treatment research biopsies will be mandatory, where clinically feasible. The trial aims to accrue a total of 25 participants. The primary end point is progression free survival. Secondary outcomes include safety, overall survival, and clinical benefit rate, defined as complete response, partial response and stable disease (per RECIST 1.1) lasting above 4 months. Correlative studies include evaluating changes in 2-HG plasma levels during treatment, and transcriptomic profiling. The study has just started enrolling in the CCR. Clinical trial registry: NCT06176989. Clinical trial information: NCT06176989 .

Development of a multiparametric prognostic score based on PAM50, in patients with HR+/HER2- advanced breast cancer (aBC) treated with endocrine therapy (ET) plus cyclin dependent kinase 4 and 6 inhibitors (CDKi), within the CDK-PREDICT (SOLTI-1801) study and HCB cohort.

1061 Background: CDKi + ET combinations have demonstrated efficacy in improving progression-free survival (PFS) and overall survival (ribociclib) in HR+/HER2- aBC in the first-line setting. Intrinsic subtypes (IS) are prognostic and predict benefit from CDKi + ET. The multiparametric PAM50MET score has demonstrated prognostic value prior to the widespread use of CDKi in HR+/HER2- aBC patients. Here we developed a new prognostic score based on PAM50 assay from metastatic baseline biopsies prior to CDKi + ET within the CDK-PREDICT (SOLTI-1801) study and the Hospital Clinic de Barcelona (HCB) cohort. Methods: RNA from FFPE tumors was analyzed at the nCounter (Nanostring Technologies) using a 72 custom gene panel including the PAM50 genes. Intrinsic subtyping (luminal A, luminal B, HER2-enriched, basal-like, and normal-like) was performed using the research-based PAM50 IS predictor. The following parameters were used to develop the predictive score: PAM50 subtype assignments, PAM50 subtype expression signatures (PAM50 scores), expression of 72 individual genes included in the custom panel (PAM50 and no PAM50 genes) and 14 clinical variables. Parameters were assessed individually and all in combination. The most parsimonious model with the highest Harrel C-index (C-index) was selected. The prognostic value of the new model was assessed using multivariable Cox regression models (adjusting by endocrine sensitivity, visceral disease, and de novo metastatic disease) as a continuous variable and as a categorical variable. Results: Between May 2020 and May 2022, 185 patients (113 from CDK-PREDICT study and 72 from HCB cohort) diagnosed with HR+/HER2- aBC were evaluated. The combined model (CDK-SCORE) that achieved the highest C-index (table) included 4 clinical variables (ECOG, liver metastases, progesterone receptor expression and Ki-67), 6 genes as a continuous variable (AR, BRCA1, CCND1, CCNE1, PGR and FGFR4) and HER2-enriched and basal-like subtypes PAM50 scores. CDK-SCORE as a continuous variable was associated with PFS (aHR: 2.77, 95% CI 2.12 – 3.61). The median PFS of CDK-SCORE LOW patients was 32.9 months (95% CI 23.3 – NA) vs 16.3 months (95% CI 12.1 – 19.7) in CDK-SCORE HIGH patients (aHR: 2.76, 95% CI 1.74 – 4.37). CDK-SCORE was also categorised by tertiles and quartiles and mPFS and Kaplan-Meier curves will be presented. Conclusions: The combined CDK-SCORE demonstrates prognostic value in patients diagnosed with HR+/HER2- aBC and treated with ET+CDKi in the first-line setting. Future plans include conducting an external validation of the CDK-SCORE. [Table: see text]

A pilot trial of personalized neoantigen pulsed autologous dendritic cell vaccine as adjuvant treatment in hepatocellular carcinoma.

e16264 Background: The primary treatment for hepatocellular carcinoma (HCC) is radical surgery. However, HCC has a high propensity to recur postoperatively and no standard adjuvant therapies have been approved. This Phase I trial aims to evaluate the safety and efficacy of an adjuvant personalized neoantigen pulsed autologous dendritic cell vaccine (Neo-DCVac-02) in patients with HCC. Methods: Eligible patients had histologically confirmed high-risk HCC after radical surgery. After obtaining the necessary baseline biopsy specimens and PBMCs of appropriate quality for DNA and RNA sequencing, neoantigen prediction, screening and synthesis were performed. Subsequently, leukapheresis was performed and DCs were isolated and cultured. DCs were then pulsed with neoantigen peptides to produce Neo-DCVac-02. On day 0, patients were treated with cyclophosphamide at a dose of 250 mg/m2. The prepared Neo-DCVac-02 vaccine was administered subcutaneously to the axillary and inguinal regions bilaterally on day 1, followed by daily administration of GM-CSF at a dose of 0.075 mg for 5 days (days 2-6). The primary objectives of this study were to assess feasibility and safety/tolerability. Secondary objectives included evaluation of immune responses (via vaccine response: IFNγ ELISpot), relapse-free survival (RFS) and overall survival (OS). Results: A total of 32 patients provided informed consent to initiate the process of personalized neoantigen discovery, of which 26 (81%) met the requirements for successful product selection for clinical manufacturing. Feasibility was demonstrated with 13 patients receiving Neo-DCVac-02. 13 patients did not receive the neoantigen vaccine (7 due to progressive disease, 6 due to withdrawal of informed consent because of COVID-19). The treatment was well tolerated with no grade 2+ treatment-related adverse events (TRAEs). The most common Grade 1 TRAEs were injection site reactions (75%), rash (16.7%), fatigue (8.3%), neutropenia (8.3%), and headache (8.3%). Five of 13 evaluable patients showed increased antigen-specific T-cell activity and more than 50% of the neoantigen peptides in Neo-DCVac-02, and sustained cellular responses were observed up to one year. Increases in T-cell activation/co-stimulation seen after treatment with Neo-DCVac-02, as demonstrated by flow cytometric analysis, suggest immune priming. At a median follow-up of 29.7 months, median RFS was not reached, with 1- and 2-year RFS of 84.6% and 60%, respectively, and all patients are alive. Patients with a strong immune response had a longer median relapse-free survival (not reached) compared to patients with a weak immune response (17.6 months, P = 0.003). Conclusions: These data demonstrate that Neo-DCVac-02 is safe, well tolerated and capable of inducing durable antigen-specific lymphocyte immune responses that may correlate with delayed HCC recurrence. Clinical trial information: NCT04147078 .

Abstract PS16-03: Intratumoral dosing of INT230-6 in Early-Stage Breast Cancer Patients Induces Tumor Cell Necrosis and Immunomodulatory Effects: A Phase II Randomized Window-Of-Opportunity Study – the INVINCIBLE Trial

Abstract Background: Larger tumors pose an increased risk for breast cancer (BC) recurrence post-surgery. In addition, most BC outside of the triple negative subtype are considered immunological quiescent and minimally responsive to immunotherapies. One potential method to combat disease recurrence risk and induce immune activation pre-surgery is through a local therapy that could cause cell death to expose tumor antigens, provide adjuvants for anti-tumor immune priming, and thus potentially increase responsiveness to immunotherapies or rates of pathological complete response in combination with chemotherapy. We have conducted a randomized, Phase 2 presurgical Window-Of-Opportunity trial for intratumoral (IT) INT230-6 comprising vinblastine, cisplatin and a diffusion enhancer (SHAO) in patients with early-stage operable BC, the INVINCIBLE trial (NCT04781725). Previous in vivo and clinical studies demonstrated that INT230-6 induces cancer cell death and halts replication while maturing dendritic cells and recruiting T-cells into the tumor. In this trial, IT injections of INT230-6 were conducted to 1) evaluate the safety of regional cytotoxic use on BC, 2) assess the drug’s ability to cause necrosis, 3) assess immune response within the tumor, microenvironment and systemically prior to surgical resection, and 4) understand the genetic pathways involved in immune activity. Methods: Women awaiting surgery for newly diagnosed early-stage intermediate or high-grade T1-T2 invasive BC were recruited to the trial. The study has two parts. Part I was a randomized (2:1) open label trial comparing 1-3 doses of INT230-6 injected weekly versus no treatment prior to surgery to evaluate safety, feasibility, and optimal drug dosing. Part II was a double-blinded randomized (2:1) trial where patients received one IT dose of INT230-6 vs saline injection IT. Results: We successfully recruited 91 patients with age ranges of 40-77 yrs (mean of 60 yrs) with tumor size ranging from 1.1 - 4.8 cm (mean 2.5 cm; SD 0.9 cm). The most common (>10%) AEs were injection site pain, injection site reaction and nausea/vomiting. Approximately 90% of AEs were grade 1. In the study INT230-6 induced necrosis in 64% of subjects (37 out of 58, range 0 to 100%); whereas saline induced partial necrosis in 25% of patients (5 out of 20, range 0 to 10%). The table below shows the results of necrosis for INT230-6 use in the entire study compared to saline injection for all subjects and those with tumors of size T2. A single injection of INT230-6 caused necrosis in various histologies, including invasive lobular carcinoma. Gene expression analysis showed significant differential gene expression between the baseline biopsy and surgical specimens using INT230-6. Pathway analysis identified genes associated with TCR signaling, B cells and T cell activation that were significantly upregulated in the post INT230-6 treatment samples. There was a relative increase in CD4 and CD8 T cells and B and mast cells. Conclusion: Preliminary evidence shows that a single dose of INT230-6 can cause significant intratumoral necrosis compared to saline especially in tumors >2. cm. INT230-6 stimulates an immune response in breast cancers prior to surgery with minimal adverse effects and good tolerability. Given its immune activation properties, INT230-6 shows promising potential in future breast cancer neoadjuvant studies. Table 1: INVINCIBLE Study Tumor Necrosis Results Intratumoral INT230-6 injection compared to IT saline injection Citation Format: Angel Arnaout, Lewis Bender, Megan Hopkins, Vanessa Lopez Ozuna, Linda Liao, Susan Robertson, Vida Talebian, Kianoosh Keyhanian, Arif Awan, Franco Abbate, Ian Walters, Gregory Pond, John Bartlett, Lazlo Radvanyi, Melanie Spears. Intratumoral dosing of INT230-6 in Early-Stage Breast Cancer Patients Induces Tumor Cell Necrosis and Immunomodulatory Effects: A Phase II Randomized Window-Of-Opportunity Study – the INVINCIBLE Trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS16-03.

Abstract PO5-21-06: Pathway profiling for prediction of response to neoadjuvant Letrozole therapy in ER positive postmenopausal breast cancer: gaining new insights for targeted treatment

Abstract Introduction: The NEOLBC (NCT03283384) study included postmenopausal patients with hormone receptor positive (ER≥50%, PR any), HER2 negative, stage II/III breast cancer. A baseline biopsy was taken prior to start letrozole treatment and after two weeks of treatment. Based on the two week Ki67-IHC, patients were randomized (Ki67 ≥1%) to receive either Letrozole + Ribociclib or standard chemotherapy until surgery, or continued (Ki67 < 1%) Letrozole mono therapy. Here we describe the signal transduction pathway profiles to better understand the molecular mechanisms of response to neoadjuvant letrozole. Methods: Signal transduction pathway activities for the ER, AR, MAPK, PI3K, HH, TGFβ and Notch pathways were measured on baseline and two weeks samples using the OncoSIGNal qPCR test (InnoSIGN). High pathway activity in a tumor sample was defined as pathway activity value above the 95th percentile of reference normal epithelial breast tissue. The pathway activity patterns of the Ki67 < 1% (n=30) and Ki67 > 1% (n=63) groups were compared between baseline and two weeks of treatment. Results: Although all measured baseline samples (n=93) were ER IHC staining positive (≥50%), there is a large range in baseline ER signal transduction pathway activity (32 to 78 on a scale from 0 – 100) and 20% of the samples show an ER-activity range (32 - 45) that normally falls in the range of ER IHC stained negative breast tissue. The group with Ki67 > 1% after 2 weeks Letrozole treatment showed non elevated ER pathway activity at baseline more often (25%) compared to the Ki67 < 1% group (10%). 92% of the patients showed a decrease in ER pathway (11.6 ± 8.6) activity after 2 week letrozole treatment compared to baseline (p=8.5e-13). Interestingly, baseline AR pathway activity has a good differentiating predictive value for the two week response to letrozole treatment and the overall AR pathway activity score was higher in the low Ki67 group (51.4 ± 7.4) than in the Ki67 ≥ 1% group (46.7 ± 6.4; p=0.0053) and more often classified as high in 30% of the low Ki67 group vs. 13% of the Ki67 ≥ 1% group. The Ki67 > 1% group showed activation of non-hormonal pathways (PI3K, MAPK and/or HH) more frequent (38%) at baseline compared to the < 1% Ki67 group (19%). Conclusion: Positive ER staining does not always relate to a high ER pathway activity, possibly explaining that not all patients respond equally well to ER inhibition therapy. Activation of hormonal pathways (ER, but also AR) appear to be predictive for early (2 weeks) response towards Letrozole as assessed by Ki67 staining. Involvement of non-hormonal pathways is associated with less effective response towards Letrozole alone. Pathway activity patterns could improve insight to underlying hormonal treatment escape mechanisms which could lead to alternative treatment options in patients with ER-positive breast cancer. Citation Format: Nadia de Gruil, Anne Florine de Groot, Yvonne Wesseling-Rozendaal, Diederick Keizer, Sigi Neerken, Judith Kroep. Pathway profiling for prediction of response to neoadjuvant Letrozole therapy in ER positive postmenopausal breast cancer: gaining new insights for targeted treatment [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-21-06.

Abstract PO5-12-09: A Single-Arm Pilot Study of the Feasibility and Efficacy of Electro-Acupuncture in Subjects with Chemotherapy-Induced Peripheral Neuropathy

Abstract Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a very common dose-limiting side effect of many cancer treatments. However, the optimal treatment for CIPN remains unclear. Electroacupuncture (EA) is a non-pharmacologic treatment that combines traditional acupuncture with electrical stimulation. EA is being examined for CIPN and has shown modest benefits. Design: This is a pilot, single-center, prospective, single-arm, non-blinded study. All subjects had residual grade ≥2 CIPN after having received curative intent chemotherapy for stage I-III breast cancer, completed at least 3 months prior to study enrollment. Patients received 10 sessions of electro-acupuncture, administered by a licensed professional, over the course of 7 weeks. A sub-group of patients also had baseline and post-treatment skin punch biopsies to assess intra-epithelial nerve density (IEND). The primary objective was to determine the feasibility of completing a 10-treatment EA program in this patient population. Feasibility was defined as ≥15 subjects completing ≥8 EA treatments. Secondary endpoints included neuropathic pain, as assessed by the Brief Pain Inventory-Short Form (BPI-SF), and change in the quality of life, as assessed by the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-NTX) subscale. Results: Twenty eligible female subjects were included in the study, with a median age of 66.5 years (range 45-81 years old). All patients received taxane chemotherapy, with 15 (75%) patients receiving weekly paclitaxel, 4 (8%) patients receiving Taxotere every 3 weeks, and 1 (2%) patient received weekly abraxane. The duration between chemotherapy completion and EA treatment initiation ranged between 4-92 months, with a median of 29 months. Eight (40%) patients were taking gabapentin, 2 (10%) on duloxetine, 1 (5%) pregabalin, and 3 (15%) on NSAIDS before and during the study. The study met its primary endpoint of feasibility, with 18 of 20 (90%) patients completing 8 or more EA sessions. Pain level, as assessed by the worst pain score on BPI-SF, improved significantly from a mean of 6.3 to 3.7, 2 weeks after completion of EA treatments (p = .0058). FACT/GOG-NTX quality of life measurement, “I am bothered by side effects of my treatment” also significantly improved from a mean score of 2.1 to 0.8 (p = .0177). There were no major adverse events (AEs) related to EA. Nine mild AEs were noted among 6 (30%) patients; localized skin biopsy site infections: G1=3, G2=3, nonlocalized cellulitis G3=1, Fatigue G1-2 =2. The localized skin biopsy site infections led to the discontinuation of further skin biopsy procedures. [We will also present data on the IEND for the nine patients who have paired before and after skin punch biopsies – this will be available at the time of the conference.] Conclusion: Electroacupuncture is a feasible treatment for CIPN. Furthermore, this pilot study did show a benefit for perceived pain and quality of life. Further studies will need to be conducted in regards to longevity of response. As larger studies in the future confirm the benefit of acupuncture, insurance payors are more likely to cover this important service. Citation Format: Nikitha Vobugari, John Paul Liang, Loni Savage, Dharamvir Jain, Kai Sun, Hanh Mai, Jenny Chang, Monica Desai, Tejal Patel, Polly Niravath. A Single-Arm Pilot Study of the Feasibility and Efficacy of Electro-Acupuncture in Subjects with Chemotherapy-Induced Peripheral Neuropathy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-12-09.

Abstract RF02-06: AVIATOR/TBCRC045: A randomized phase II study of vinorelbine (N) + trastuzumab (H) alone or combined with avelumab (A) +/- utomilumab (U) in patients (pts) with HER2+ metastatic breast cancer (MBC) (NCT03414658)

Abstract Background: Chemotherapy (chemo) + H is standard of care therapy for pts with refractory HER2+ MBC. It is unknown whether the addition of immune checkpoint inhibitor (ICI) or a 4-1BB agonist (U) improves efficacy of standard chemo + H for this population. Methods: Eligible pts had HER2+ MBC previously treated with H, pertuzumab (P), and T-DM1. Pts previously treated with N or ICI were excluded. 100 pts were randomized 1:2:2 to tx with NH, NHA, or NHAU. ER status and presence of liver metastases were stratification factors. The original co-primary objectives were to compare progression-free survival (PFS) of (1) NHA vs NH; and (2) NHAU vs NHA. In 2021, due to discontinuation of clinical development of U, an unplanned interim futility analysis reviewed by IDMC led to closure of NHAU and randomization of the final 13 pts to NH or NHA. For the comparison of NH vs NHA, with 60 pts randomized (20 vs 40) there was 88% power for a log-rank test to detect improvement in median PFS (mPFS) from 2 to 4 mos with one-sided alpha of 0.1. Corresponding 2-sided 80% confidence intervals (CI) were reported for the stratified Cox model hazard ratios (HR), along with stratified one-sided log-rank p-value. Secondary endpoints included overall response rate (ORR), duration of response (DOR), and safety/tolerability. Results: 100 pts were randomized from 7/2018-3/2023, and 97 pts started tx on trial: 18 NH, 45 NHA, and 34 NHAU (prior to its closure). Pts were 99% female, with median age 54 yrs (range 26-78 yrs); 70% White, 14% Black, and 8% Asian; 7% were Hispanic. 66% of pts had hormone receptor-positive tumors, and 76% had visceral metastases. All pts were previously treated with H, P, and T-DM1, and 17% had prior trastuzumab deruxtecan. 63% of pts had received ≥3 lines of HER2 tx for MBC (range 1-13 lines), and median interval from MBC diagnosis to randomization was 32 mos (interquartile range 22-61 mos). mPFS and ORR results are shown in the Table. One patient remained progression-free on tx at analysis. NHA was associated with a statistically significant improvement in PFS compared to NH (HR=0.56 (80% CI 0.37-0.86, p=0.04)). No difference in PFS was observed between NHAU vs NHA (HR=1.20 (80% CI 0.84-1.73) as final estimate after closure of NHAU for futility). Of 9 pts with confirmed responses in NHA arm, 3 pts had DOR >12 mos. Grade 3-4 treatment-emergent adverse events (AEs) were similar by tx: 61% NH, 62% NHA, and 67% NHAU. There were no grade 5 treatment-related AEs. Immune-related all grade AEs in the A-containing arms (n=79 safety-evaluable pts treated with A) included: AST increase (n=15), ALT increase (n=9), hyper/hypothyroidism (n=8), adrenal insufficiency (n=2), and pneumonitis (n=1), of which two events were grade 3 (adrenal insufficiency and AST increase) and none were grade 4. Only 3 pts (1 in NHA; 2 in NHAU) stopped trial tx for unacceptable AEs. Required baseline and on-tx biopsies were performed; PD-L1 and TIL data will be presented. Conclusions: This trial demonstrated significant improvement in PFS with addition of avelumab to NH among pts with heavily pre-treated HER2+ MBC. 4-1BB agonist did not improve PFS. To our knowledge, this is the first randomized trial to report results of chemo/H +/- ICI in HER2+ MBC. Further investigation of ICI with chemo/H for pts with refractory HER2+ MBC is warranted, and the potential predictive value of immune biomarkers should be explored. *one-sided stratified log rank test p-value Citation Format: Adrienne Waks, Ruichao Shi, Meredith Regan, Chau Dang, Cesar Santa-Maria, Kelly Westbrook, Vandana Abramson, Rashmi Murthy, Rita Nanda, Hope Rugo, Amy Clark, Candace Mainor, Claire Dees, Valentina Hoyos, Kathy Miller, Erica Stringer-Reasor, Natasha Hunter, Sun Young Oh, Michelle DeMeo, Amanda Okpoebo, Erin Elias, Busem Kurt, Nancy Lin, Mothaffar Rimawi, Antonio Wolff, Elizabeth Mittendorf, Shom Goel, Sara Tolaney, Sherene Loi, Ian Krop. AVIATOR/TBCRC045: A randomized phase II study of vinorelbine (N) + trastuzumab (H) alone or combined with avelumab (A) +/- utomilumab (U) in patients (pts) with HER2+ metastatic breast cancer (MBC) (NCT03414658) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr RF02-06.

Abstract PS17-01: Key drivers of therapeutic response and resistance to giredestrant from GO39932: a Phase Ia/b study in patients with estrogen receptor-positive, HER2-negative, locally advanced or metastatic breast cancer

Abstract BACKGROUND Several investigational oral selective estrogen receptor antagonists and degraders (SERDs) are under investigation. These were partly developed to benefit patients (pts) with breast cancer (BC) who acquired resistance to standard-of-care (SoC) endocrine therapies (ET); e.g., through gain of ESR1 mutations that enable estrogen-independent ER activity. One such SERD, giredestrant (G), demonstrates activity in pts with ESR1-wild type (WT) or -mutant (m) tumors, and in pts who progressed on other ETs. Results from Phase I/III trials in ER-positive, HER2-negative, locally advanced/metastatic BC (ER+, HER2– LA/mBC) showed that next-generation SERDs had increased activity in ESR1m tumors vs SoC ETs. However, enthusiasm was hindered by heterogeneous responses, driven in part by study design differences. Across acelERA BC (NCT04576455), EMERALD (NCT03778931), SERENA-2 (NCT04214288), and AMEERA-3 (NCT04059484), 30–50% of pts progressed rapidly (< 2 months) when treated with SoC ETs or next-generation SERDs, while others benefited for ≥ 1 year. We present an exploratory biomarker analysis aimed at understanding the mechanistic basis for heterogeneous responses to SERDs in ER+, HER2– LA/mBC, by assessing a Phase Ia/b G cohort (NCT03332797) with paired baseline and on-treatment (tx) biopsies. METHODS Pts had ≤ 2 prior therapies for LA/mBC; disease recurrence/progression while on adjuvant ET for ≥ 24 months and/or ET for ER+, HER2– LA/mBC; and tumor response/stable disease for ≥ 6 months. Single-agent dose-escalation stage: 10, 30, 90, or 250 mg G once daily (QD) on Days (D) 1–28 of 28-D cycles (C). Dose-expansion stage: 30, 100, or 250 mg G QD. 100 mg G + 125 mg palbociclib on a 21-D on/7-D off schedule was also explored. Pre-/perimenopausal pts received LHRH agonists. Paired pre- and on-tx (C2D8) tumor biopsies (n = 29) were immunolabeled for ER, progesterone receptor, and Ki67, and assessed via bulk RNA-sequencing. Pre-tx liquid biopsies (n = 85) were evaluated by FoundationOne Liquid CDx assay. To validate our clinical observations, we generated a SERD-resistant MCF7 cell line and tested its sensitivity to other therapies. RESULTS We compared fast-progressing pts (FP; progression-free survival [PFS] < 2 months) with those experiencing long-term benefit (LTB; PFS > 12 months). LTB was significantly associated with high tumor baseline ER pathway activity. Although the benefit of G was of larger magnitude among pts with ESR1m tumors compared with SoC ET in acelERA BC, here pts with predominantly ESR1WT tumors received LTB on G tx. At the molecular level, G acted on LTB tumors by suppressing cell cycle- and ER-associated genes. In contrast, G had no effect on the transcriptome of FP tumors, which had lower baseline ER activity than LTB tumors. FP tumors were instead enriched for multiple cancer-associated pathways, e.g., RAS/MAPK and PI3K, which may drive resistance to G and thus enable fast progression. By liquid biopsy, most FP pts (> 90%) did not harbor a mutation in the associated pathway (e.g., NF1, KRAS), and thus could not be identified by genomic profiling alone. FP tumors were instead enriched for multiple cancer-associated pathways by gene expression. We explored these mechanisms further in the SERD-resistant cell line, which was similarly enriched for EGFR and MAPK activation vs standard MCF7 cells. Although cells became resistant to ER-targeted drugs, they acquired sensitivity to EGFR/MAPK inhibitors e.g., gefitinib, cobimetinib. CONCLUSIONS We identified molecular features associated with LTB to G and revealed a set of oncogenic pathways associated with FP pts on tx; demonstrating that these pathways represent acquired dependencies and potential therapeutic targets for SERD-resistant tumors and FP pts. Citation Format: Jackson Liang, Christy Ong, Jennifer Giltnane, Junko Aimi, Ching-Wei Chang, Mary Gates, Jennifer Eng-Wong, Pablo Perez-Moreno, Komal Jhaveri, Elgene Lim, Nicholas Turner, Heather Moore. Key drivers of therapeutic response and resistance to giredestrant from GO39932: a Phase Ia/b study in patients with estrogen receptor-positive, HER2-negative, locally advanced or metastatic breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS17-01.

Abstract PO1-20-06: Phase 2 study of novel HER2-targeting, TLR7/8 immune-stimulating antibody conjugate (ISAC) BDC-1001 +/- pertuzumab in patients with HER2-positive metastatic breast cancer (MBC) previously treated with trastuzumab deruxtecan

Abstract Background: Therapies to effectively manage patients (pts) with metastatic HER2+ breast cancer have significantly improved over the years, but improvement is still needed in both efficacy and tolerability. BDC-1001 is an ISAC consisting of a trastuzumab biosimilar conjugated to a proprietary cell membrane impermeable TLR7/8 agonist via a non-cleavable linker, administered IV every 2 weeks. It is designed to trigger the innate immune system and generate a durable tumor-targeted adaptive immune response. Preclinical studies indicate that HER2-targeted ISACs elicit potent and durable immune-mediated antitumor efficacy, leading to complete tumor regression in a TLR- and Fc receptor-dependent manner [1]. Moreover, preclinical studies with a murine surrogate of BDC-1001 (trastuzumab-T785 ISAC) indicate improved anti-tumor activity with trastuzumab-T785 compared with trastuzumab/pertuzumab. In these preclinical studies, the combination of trastuzumab-T785 and pertuzumab demonstrated significantly enhanced efficacy in multiple HER2-expressing tumor models, including those with lower HER2 expression [1]. The addition of pertuzumab decreased the quantity of ISAC required for anti-tumor activity in the JIMT-1 HER2 IHC2+ model. Moreover, the combination of pertuzumab with the ISAC significantly increased the cytokine and chemokine concentrations in the tumor xenografts, compared with monotherapy or trastuzumab/pertuzumab, indicating enhanced myeloid activation in the tumor. These preclinical studies suggest that this combination may enhance the clinical activity of trastuzumab-based ISACs. The completed part of the BDC-1001 dose escalation trial (NCT04278144) demonstrated safety, PK and pharmacodynamic changes compatible with the ISAC mechanism of action, and a wide range of antitumor activity (incl. cases with breast cancer); resulting in a RP2D of 20 mg/kg q2w [2]. Two trials are underway, including a Phase 2 trial in other HER2+ malignancies, and a randomized Phase 2 trial with BDC-1001 alone and in combination with pertuzumab in patients with HER2-positive MBC previously treated with 2 or more prior anti-HER2 therapies, including trastuzumab deruxtecan. Methods: The Phase 2 multicenter, open-label, randomized study (BBI-20231001) is enrolling up to 66 pts with HER2-positive (ASCO/CAP guidelines 2018) MBC previously treated with 2 or more prior anti-HER2 therapies, including trastuzumab deruxtecan as one of the prior therapies. Pts must be 18 years or older, have measurable disease (RECIST v1.1), and have Eastern Cooperative Oncology Group performance status of 0 or 1. Pts will be administered BDC-1001 20 mg/kg every 2 weeks (IV q2w) and randomized 1:1 to receive BDC-1001 as a single agent or in combination with pertuzumab. The trial has a Simon 2-stage design within each arm. The primary objective is to determine the overall response rate per RECIST v1.1 of BDC-1001 alone and in combination with pertuzumab. Secondary objectives will evaluate safety, additional efficacy parameters, pharmacokinetics, and immunogenicity of BDC-1001 alone and in combination with pertuzumab. Exploratory objectives will include pharmacodynamic biomarkers in tumor tissue (baseline and on-treatment biopsies if feasible) and in peripheral blood to elucidate the mechanism of action and seek to identify biomarkers associated with BDC-1001 biological activity with or without pertuzumab. This study is expected to initiate accrual in 2H 2023. For additional information, please contact Bolt Biotherapeutics at 1-650-665-9295 or info@boltbio.com.

Abstract PS12-06: A phase 2 study of abemaciclib monotherapy for patients with retinoblastoma-positive (Rb+), triple-negative metastatic breast cancer

Abstract Background: Cyclin-dependent kinase (CDK) 4/6 inhibitors can significantly extend survival when given in combination with endocrine therapy as treatment for hormone receptor-positive metastatic breast cancer. Preclinical studies suggest CDK4/6 inhibitor monotherapy might also be effective in a subset of triple-negative breast cancers (TNBCs), including those that express a functional retinoblastoma (RB) protein and/or those of the Luminal Androgen Receptor (LAR) subtype. Currently, the clinical activity of CDK4/6 inhibitor therapy in TNBC has not been reported. Methods: We conducted a single-arm phase II study of abemaciclib monotherapy in patients with locally advanced or metastatic TNBC. Key eligibility criteria included: (i) Measurable disease by RECIST 1.1; (ii) Between 1-3 prior lines of systemic therapy for advanced TNBC; (iii) RB-positive tumor (defined as ≥ 50% of tumor cells staining positive for RB by immunohistochemistry [archival or fresh sample] on central testing); (iv) ECOG PS 0/1. Patients were treated with abemaciclib 200 mg orally (28-day cycles) twice daily until disease progression, unacceptable toxicity, withdrawal of consent, or death. Tumor biopsies were mandatory at baseline and C2D1 if tumor tissue was safely accessible. The primary outcome was objective response rate (ORR). Key secondary endpoints included progression-free survival (PFS), overall survival (OS), clinical benefit rate (CBR: CR + PR + SD ≥ 24 weeks), and safety and tolerability. The study had a two-stage design. Thirteen patients were enrolled in the first stage, with the plan to enrol a further 25 patients if at least one objective response was observed. Results: One unconfirmed partial response was observed in stage 1, and a total of 27 patients were enrolled before the trial was closed early due to slow accrual. The median age was 61 years and patients had received a median of 2 prior lines of systemic therapy for metastatic disease. Twelve patients had received prior immunotherapy. After a median follow-up of 28.5 months, the confirmed ORR was 0% and the CBR was 15%, with 4 of 27 patients experiencing stable disease for ≥ 24 weeks. The median PFS was 1.94 months (95% CI: 1.8 – 11.5 months), and the median OS was 8.44 months (95% CI: 4.6 – 15.6 months). There was no significant difference in PFS or OS between patients with PD-L1-positive versus PD-L1-negative disease, or Androgen Receptor (AR) positive versus negative tumors by immunohistochemistry. The most common adverse events of grade 2 or higher were diarrhea (41%), neutropenia (41%), anemia (30%), and nausea (30%). RNA-sequencing of baseline biopsies has been performed to identify biomarkers associated with clinical benefit, and results will be presented at the meeting. Conclusions: Abemaciclib monotherapy did not show clinical activity in patients with Rb+ metastatic TNBC. This finding suggests that future trials of CDK4/6 inhibition as monotherapy in TNBC are not warranted. Citation Format: Shom Goel, Bojana Jovanović, Xiangying Chu, Melissa Hughes, Ayesha Mohammed-Abreu, Julie Kasparian, Timothy Erick, Molly DiLullo, Eileen Wrabel, Rinath Jeselsohn, Nabihah Tayob, Stuart Schnitt, Nancy Lin, Sara Tolaney. A phase 2 study of abemaciclib monotherapy for patients with retinoblastoma-positive (Rb+), triple-negative metastatic breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS12-06.

A Modular Trial of Androgen Signaling Inhibitor Combinations Testing a Risk-Adapted Strategy in Patients with Metastatic Castration-Resistant Prostate Cancer.

To determine the efficacy and safety of risk-adapted combinations of androgen signaling inhibitors and inform disease classifiers for metastatic castration-resistant prostate cancers. In a modular, randomized phase II trial, 192 men were treated with 8 weeks of abiraterone acetate, prednisone, and apalutamide (AAPA; module 1) and then allocated to modules 2 or 3 based on satisfactory (≥50% PSA decline from baseline and <5 circulating tumor cell/7.5 mL) versus unsatisfactory status. Men in the former were randomly assigned to continue AAPA alone (module 2A) or with ipilimumab (module 2B). Men in the latter group had carboplatin + cabazitaxel added to AAPA (module 3). Optional baseline biopsies were subjected to correlative studies. Median overall survival (from allocation) was 46.4 [95% confidence interval (CI), 39.2-68.2], 41.4 (95% CI, 33.3-49.9), and 18.7 (95% CI, 14.3-26.3) months in modules 2A (n = 64), 2B (n = 64), and 3 (n = 59), respectively. Toxicities were within expectations. Of 192 eligible patients, 154 (80.2%) underwent pretreatment metastatic biopsies. The aggressive-variant prostate cancer molecular profile (defects in ≥2 of p53, RB1, and PTEN) was associated with unsatisfactory status. Exploratory analyses suggested that secreted phosphoprotein 1-positive and insulin-like growth factor-binding protein 2-positive macrophages, druggable myeloid cell markers, and germline pathogenic mutations were enriched in the unsatisfactory group. Adding ipilimumab to AAPA did not improve outcomes in men with androgen-responsive metastatic castration-resistant prostate cancer. Despite the addition of carboplatin + cabazitaxel, men in the unsatisfactory group had shortened survivals. Adaptive designs can enrich for biologically and clinically relevant disease subgroups to contribute to the development of marker-informed, risk-adapted therapy strategies in men with prostate cancer.

A paclitaxel-hyaluronan conjugate (ONCOFID-P-B™) in patients with BCG-unresponsive carcinoma in situ of the bladder: a dynamic assessment of the tumor microenvironment

BackgroundThe intravesical instillation of the paclitaxel-hyaluronan conjugate ONCOFID-P-B™ in patients with bacillus Calmette-Guérin (BCG)-unresponsive bladder carcinoma in situ (CIS; NCT04798703 phase I study), induced 75 and 40% of complete response (CR) after 12 weeks of intensive phase and 12 months of maintenance phase, respectively. The aim of this study was to provide a detailed description of the tumor microenvironment (TME) of ONCOFID-P-B™-treated BCG-unresponsive bladder CIS patients enrolled in the NCT04798703 phase I study, in order to identify predictive biomarkers of response.MethodsThe composition and spatial interactions of tumor-infiltrating immune cells and the expression of the most relevant hyaluronic acid (HA) receptors on cancer cells, were analyzed in biopsies from the 20 patients enrolled in the NCT04798703 phase I study collected before starting ONCOFID-P-B™ therapy (baseline), and after the intensive and the maintenance phases. Clinical data were correlated with cell densities, cell distribution and cell interactions. Associations between immune populations or HA receptors expression and outcome were analyzed using univariate Cox regression and log-rank analysis.ResultsIn baseline biopsies, patients achieving CR after the intensive phase had a lower density of intra-tumoral CD8+ cytotoxic T lymphocytes (CTL), but also fewer interactions between CTL and macrophages or T-regulatory cells, as compared to non-responders (NR). NR expressed higher levels of the HA receptors CD44v6, ICAM-1 and RHAMM. The intra-tumoral macrophage density was positively correlated with the expression of the pro-metastatic and aggressive variant CD44v6, and the combined score of intra-tumoral macrophage density and CD44v6 expression had an AUC of 0.85 (95% CI 0.68–1.00) for patient response prediction.ConclusionsThe clinical response to ONCOFID-P-B™ in bladder CIS likely relies on several components of the TME, and the combined evaluation of intra-tumoral macrophages density and CD44v6 expression is a potentially new predictive biomarker for patient response. Overall, our data allow to advance a potential rationale for combinatorial treatments targeting the immune infiltrate such as immune checkpoint inhibitors, to make bladder CIS more responsive to ONCOFID-P-B™ treatment.

Abstract CT273: Unique multicenter trial design to investigate ARTIDIS nanomechanical generated measurements for early breast lesions (ANGEL)

Abstract Background: The conventional diagnosis of breast cancer followed by molecular subtyping for therapy selection is a lengthy process and associated with patient and clinician anxiety. Efficient, bedside approaches are desirable to drive fast diagnosis and early planning of clinical management. This clinical trial (NCT06085833) tackles the novel concept of automated and reliable tissue diagnostics (ARTIDIS) based on the measurement of nanomechanical signature of fresh clinical biopsies from patients with breast lesions. This study is based on our previous single center clinical study (Basel NANO) where tissue nanomechanical signature can: 1) reliably distinguish benign and malignant breast lesions, 2) predict the presence of metastatic disease based on imminent aggressiveness rating and 3) predict the response to neoadjuvant chemotherapy from baseline biopsies. The current study aims to prospectively validate the efficacy of ARTIDIS system as an aid to diagnosis, assessment of breast cancer prognosis and prediction of therapy response, particularly in the context of neoadjuvant therapy (Natira). Methods: A cohort of 2,705 patients with breast lesions, who are clinically indicated for core needle biopsy (CNB) are being enrolled, from diverse ethnic and socioeconomic backgrounds. Single fresh CNB will be transferred into tissue preservation buffer and measured by ARTIDIS device within 1-3 hours to collect thousands of nanomechanical measurements. Undisrupted CNB will be fixed and returned to standard diagnostic workflow, remaining unaltered for downstream assessments. Nanomechanical measurement data are prospectively analyzed in a blind manner before the collection of histopathology and follow up clinical data. The primary endpoint of the study is to validate ARTIDIS potential in diagnosis of breast lesions (benign vs malignant), secondary endpoints address whether nanomechanical signature can differentiate subtypes of breast cancer, associate with clinical outcome and guide treatment decisions in NAT setting. Follow up data will be collected regularly up to 10 years after patient enrollment. Results: The multicenter ANGEL study is a prospective validation of the NANO (University Hospital Basel, Switzerland) - first ever performed clinical study which investigated the diagnostic, prognostic, and predictive value of tissue nanomechanical signature in patients with breast cancer. The ANGEL study takes advantage of ARTIDIS non-disruptive technology and is fully integrated into routine clinical workflow. The study started enrollment in 11/02/2023, and is expected to complete by 2025. The seamless integration of ARTIDIS within the standard clinical settings, its automatization, bedside implementation, and the lack of additional burden to patients enables effective reach of a diverse population through local hospitals and communities. Conclusion: This study presents the first of its kind as a direct prospective, multicenter- based translation of the tissue nanomechanical signature into clinical settings. This unique trial design allows the prospective development of ARTIDIS as an aid to diagnosis, prognosis and therapy optimization in patients with breast cancer. The innovative trial design of this study may also further the development of strategies to increase reach to underrepresented communities. Citation Format: Karla A. Sepulveda, Ashley Roark, Sagar Dhamne, Chandandeep Nagi, Ivan Marin, Iqbal Tabish, Sara Nizzero, Mariam Gachechiladze, Tobias Appenzeller, Philipp Oertle, Marko Loparic, Susan G. Hilsenbeck, Marija Plodinec, Alastair Thompson. Unique multicenter trial design to investigate ARTIDIS nanomechanical generated measurements for early breast lesions (ANGEL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT273.

Abstract CT057: Phase 1/2 trial of trametinib + ceritinib in patients with unresectable melanoma

Abstract Background: In advanced melanoma, treatment options after progression on immunotherapy are limited, particularly for patients with BRAF-WT tumors. MEK-inhibitors have been explored, with limited clinical efficacy. Our pre-clinical data demonstrated efficacy of the tyrosine kinase inhibitor ceritinib in NRAS-mutant and BRAF-mutant melanoma cells lines. There was synergy observed combining the MEK inhibitor trametinib with ceritinib (compared to trametinib alone) in BRAF-WT melanoma xenografts, with dual suppression of MAPK and mTOR signaling (Verduzco et al, Mol Cancer Ther 2018) Further, in our anti-PD-1 resistant mouse melanoma models, combination of ceritinib and trametinib was highly effective when administered subsequent to anti-PD1. (Phadke et al, Cancer Immunol Res 2021) Methods: We conducted a phase 1/2 trial of ceritinib monotherapy and then combination of trametinib with ceritinib in patients with advanced melanoma after failure of anti-PD-1 (and prior BRAF/MEK inhibitors if eligible.) Primary objective was to identify the maximum tolerated dose (MTD) of this combination, with secondary objectives of tumor response (RECIST 1.1) and progression-free (PFS) and overall survival (OS). In the initial phase 2 portion to explore single-agent activity, patients received oral ceritinib monotherapy at 450 mg daily (QD). In the subsequent phase 1 portion, patients started at dose level (DL)1 of 300 mg PO QD ceritinib + 2mg PO QD trametinib, with a BOIN design to guide dose escalation in cohort sizes of 3. DL 2 was 450 mg + 2 mg QD, while DL -1 was 300 mg + 1.5 mg QD of the combination. Tumor biopsies and blood samples were obtained on day 1 and day 15. Results: We enrolled 28 patients with unresectable/metastatic melanoma. Median age was 66, 10 female, 26 stage IV, 11 NRAS-mutant, 4 BRAF V600-mutant, with median 3 prior lines of prior therapy. There was no objective response observed to ceritinib monotherapy in 11 patients; prolonged stable disease of 6 and 8 months was seen in 2 pts. Median PFS was 2.1 months (95% CI 1.91, NA); median OS was 7.3 months (95% CI 2.4, NA). Two patients had grade 3 AST/ALT elevation; there were no unexpected toxicities. Of the 17 patients on the combination regimen, 12 received DL1. Dose-limiting toxicities of grade 3 rash and grade 2 glaucoma led to de-escalating to DL -1 for other patients. Overall, most frequent grade 3/4 toxicities were grade 3 rash (n=3), grade 3 hypertension (n=2), and grade 3 ALT/AST elevation (n=2). MTD was determined at DL -1 of 1.5 mg trametinib + 300 mg ceritinib QD. Two patients had partial response (12%), both NRAS-mutant; 6 had SD (3 lasting ≥6 months). Median PFS was 3.1 months (95% CI 1.94, 6.18) with median OS of 7.8 months (95% CI 5.1, 13.2). Overall, patients with immediate prior line of anti-PD-1 before trial treatment had a trend toward improved OS (10.2 months vs 5.1 months; p=0.21); no differences were seen based on NRAS or BRAF-status. Conclusions: Ceritinib does not appear to have meaningful single agent activity in treatment-refractory advanced melanoma. Efficacy of the combination with trametinib is modest, and the inability to dose-escalate the combination due to overlapping toxicities such as rash may have contributed. Analyses from baseline and on-treatment tumor biopsies, including immunohistochemistry and single cell RNA seq to explore drug effect on mTOR and MAPK pathways as well as immune infiltration, are ongoing and will be presented. Citation Format: Zeynep Eroglu, Vivien Yin, Joseph Markowitz, Andrew Brohl, Ahmad A. Tarhini, Wenyi Fan, Deanryan De Aquino, Ann Chen, Uwe Rix, Nikhil I. Khushalani, Keiran Smalley. Phase 1/2 trial of trametinib + ceritinib in patients with unresectable melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT057.

Abstract CT059: Phase 1b trial Mipasetamab Uzoptirine (ADCT-601-102) dose escalation in patients with advanced bone and soft tissue sarcomas

Abstract Background: AXL is a cell surface receptor tyrosine kinase widely expressed in solid tumors (ST), including sarcomas. ADCT-601 (Mipasetamab uzoptirine; Mipa) is an antibody-drug conjugate comprising a humanized anti-AXL antibody conjugated via a cleavable linker to SG3199 (pyrrolobenzodiazepine dimer cytotoxin). Mipa demonstrated antitumor activity in pre-clinical mice models of sarcoma, adrenocortical carcinoma and pancreatic cancer, and clinical activity in ST patients (pts) in its first-in-human trial. Here, we report initial clinical data in pts with advanced bone and soft tissue sarcomas treated in dose escalation with Mipa. Objective: To characterize the safety and tolerability of Mipa in pts with sarcoma indications who exhausted standard of care therapy. Method: This is a phase 1b, open-label, dose-escalation, dose expansion study of Mipa (NCT05389462; EudraCT: 2021-00566-18). Pts received Mipa every 3 weeks (Q3W) at escalating dose levels, in a 3+3 dose escalation design. Results: As of 04 December 2023, 18 sarcoma patients (15 [83%], soft tissue sarcoma [STS] and 3 [17%] bone sarcoma), unselected for AXL expression, with a median number of 3 prior lines of therapy (1-10), were enrolled in 4 different dose cohorts: 7.5mg, 11mg, 13mg and 15mg. Reasons for treatment discontinuation were disease progression (10 pts [55.6%]), adverse events (3 pts [16.7%]) and consent withdrawal (2 pts [11.1%]). Treatment emergent adverse events (TEAE) were seen in 17 pts (94.4%). Most common TEAE (all grades and relationship [≥20%]) were palmar-plantar erythrodysesthesia syndrome (7 pts [38.9%]); anemia (6 pts [33.3%]); rash maculopapular (5 pts [27.8%]); cheilitis and constipation (4 pts each [22.2%]). TEAE≥grade 3 were seen in 9 pts (50%). Most common TEAE≥grade 3 (≥10%) were GGT increase (2 pts [11.1%]). Two dose limiting toxicities were seen: cheilitis grade 2 and grade 3 at 15mg and 13mg respectively. Cutaneous reactions, all grades, are more prominent in higher doses. Maximum tolerated dose (MTD) has not been established. In 17 sarcoma pts evaluable per RECISTv1.1, best overall response was partial response (PR) (2 pts [11.8%]), including a confirmed PR; stable disease (SD) (8 pts [47.1%]); progressive disease (7 pts [41.2%]). Tumor reductions was observed at 7.5mg, 11mg and 13mg. By week 12, 6/17 pts (35.3%) did not demonstrate PD . Initial IHC staining showed AXL expression in all sarcoma baseline biopsies tested so far. Initial pharmacokinetic (PK) data indicate exposures with moderate to marked interpatient variability; rapid clearance with no accumulation by Cycle 2. Updated biomarkers and PK data will be presented. Conclusion: The MTD was not established. Due to the incidence of TEAE judged related to Mipa and the preliminary activity observed, 15mg was selected as the highest dose to be tested in a fixed dose Q3W regimen. The study continues to enroll to further optimize Mipa dosing regimen and in dose escalation with gemcitabine. Citation Format: Brian Andrew Van Tine, Christopher T. Chen, Victor Moreno, Elizabeth J. Davis, Maria J. de Miguel, Antoine Italiano, Esma Saada-Bouzid, Mohammed Milhem, Claudia Valverde, Sant P. Chawla, Abdul Rafeh Naqash, Louise Carter, Robin Jones, Ilaria Conti, Joe Boni, Karin Havenith, Yvan LeBruchec, Serafino Pantano, Jean-Yves Blay. Phase 1b trial Mipasetamab Uzoptirine (ADCT-601-102) dose escalation in patients with advanced bone and soft tissue sarcomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT059.

Abstract 6550: Biopsy analysis of trial S1616: Ipilimumab plus nivolumab versus ipilimumab alone in patients with anti-PD-1 refractory melanoma

Abstract Background: The phase II randomized trial S1616 (NCT03033576) showed that patients with melanoma refractory to anti-PD-1-based therapy had improved progression free survival (HR=0.63, p=0.037) and objective response (28% vs 9%) to the combination of ipilimumab with nivolumab compared to ipilimumab. Here, we report molecular and spatial proteomic features of biopsies collected from patients on S1616, both prior to and during therapy. Methods: Biopsies collected from patients from both arms at baseline (N=68 patients total) and early on-therapy (N=51; 43 with paired timepoints) were analyzed by whole exome sequencing (n=185 samples), RNA sequencing (n=105), histopathologic staining (n=149), and multiplexed ion beam imaging (n=45). Multiple biopsies were available for some patients. Mutations, gene expression, and tumor microenvironment were compared across timepoints and response to combination (N=18 responders [CR/PR], N=44 nonresponders [SD/PD]). Results: Baseline biopsies from patients responsive to combination had increased expression of genes (n=482, FDR&amp;lt;0.05) associated with coagulation and complement, fatty acid metabolism, oxidative phosphorylation, hypoxia, and interferon gamma response gene sets (FDR&amp;lt;0.05), compared to nonresponsive biopsies. Baseline biopsies from responders also had low levels of effector CD8 T cells (PD1+, TIM-3+, GZMB+, Ki67+) colocalized with tumor cells and myeloid populations expressing higher levels of MHC Class II. On-therapy biopsies from responders showed decreased detection of driver mutations by genomics, reduced gene expression of pathways enriched at baseline (oxidative phosphorylation, complement) by transcriptomics, and increased CD8 T cell to tumor cell ratios by histopathology, supporting observations of tumor regression. On-therapy biopsies from responders also had increased gene expression of genes related to inflammatory cytokine signaling. This correlated with increased proportions of effector CD8 T cells, compared to paired baseline or nonresponding biopsies, and increased organization of nonactivated CD8 T cells near mature endothelial structures (SMA+, CD31+ regions) adjacent to tumor. Biopsies from nonresponders did not demonstrate these dynamics and instead contained exhausted CD8 T cells (PD1+, TIM-3+, granzyme B-, Ki67-) colocalized with FOXP3+, CD4+ Tregs and CD163+, PD-L1+ M2 macrophages, both at baseline and on-therapy. Conclusion: In patients with melanoma refractory to anti-PD-1, addition of anti-CTLA-4 facilitates tumor-reactive CD8 T-cell infiltration and decreased suppressor cell dynamics, resulting in regression of some tumors with distinct transcriptome features. Conversely, biopsies from patients whose tumors progress on combination therapy lack expression of metabolic pathways and show CD8 T-cells restricted in proximity to M2 macrophages and Tregs. Citation Format: Katie M. Campbell, Zaid Bustami, Daniel G. Chen, Egmidio Medina, Cynthia R. Gonzalez, Nataly Naser Aldeen, Ignacio Baselga-Carretero, Agustin Vega-Crespo, Jessica Maxey, Jia M. Chen, Lawrence F. Kuklinski, Kari L. Kendra, Bartosz Chmielowski, Thach-Giao Truong, Nikhil I. Khushalani, Frances Collichio, Alexandra Ikeguchi, Adrienne I. Victor, Kim Margolin, Jeffrey A. Sosman, Sapna P. Patel, Siwen Hu-Lieskovan, James Moon, Shay Bellasea, Daniel K. Wells, Christine N. Spencer, Marshall A. Thompson, Michael Wu, Philip O. Scumpia, Ari VanderWalde, Antoni Ribas. Biopsy analysis of trial S1616: Ipilimumab plus nivolumab versus ipilimumab alone in patients with anti-PD-1 refractory melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6550.

Abstract 6394: Tissue nanomechanical signature predicts response to neoadjuvant chemotherapy in patients with breast cancer

Abstract Background: Neoadjuvant chemotherapy (NACT) is increasingly used in patients with breast cancer. However, predicting response to NACT remains a challenge in everyday clinical practice. Increasing (pre)- and clinical evidence demonstrate the importance of cancer biomechanics in mediating therapy response. We and others have previously demonstrated that complex biomechanical alterations in cancer tissues, can be measured by the Atomic Force Microscopy (AFM) at the nanoscale level. Incorporating AFM measurements of clinical biopsies within standard of care is thus a promising avenue to leverage tissue mechanics as prognostic and predictive biomarker for solid cancers. Methods: Fresh clinical biopsy samples from 545 breast cancer patients were measured using the AFM-based Automated and Reliable Tissue Diagnostics (ARTIDIS) investigational device - ART-1. Measurements were performed on baseline biopsies within routine clinical workflow in the Breast Clinic, University Hospital Basel. This cohort comprises 30 patients who received NACT including: anthracycline and/or taxane based chemo (n=17), and anthracycline and/or taxane with platinum chemo (n=13). Study endpoints were radiological complete response (rCR) prior and pathological complete response (pCR) after surgery. Multiparametric nnanomechanical signature data has been analyzed in an automated manner using the proprietary ARTIDISNET software platform. Results: From the 30 patients who received NACT, 12 patients presented with rCR, 17 patients presented with rPR, and 1 patient presented with rNR. pCR has been achieved only in 9 patients. In this study, he ARTIDIS nanomechanical signature of response to NACT in breast cancer showed 100% negative predictive value (NPV) and 89% positive predictive value (PPV), with 93% of accuracy for patients receiving chemotherapy, independent of molecular subtype or treatment regimen. Sensitivity was 100% and specificity was 85% (AUC=0.91). Conclusion: ARTIDIS nanomechanical signature can be seamlessly integrated within clinical settings to predict response to standard of care NACT in patients with breast cancer in a prospective manner. These results are currently being validated in a global, multicentre prospective study in breast cancer (ANGEL, NCT06085833), enrolling in total 2706 patients, with the aim to support implementation of the ARTIDIS nanomechanical signature into routine clinical practice. Citation Format: Mariam Gachechiladze, Sara Nizzero, Tobias Appenzeller, Leonie Briner, Rosemarie Burian, Sabine Schädelin, Simone Muenst-Soysal, Tatjana Vlaijnic, Ellen Obermann, Sophie Dellas, Serafino Forte, Zlatko Marušić, Ahmed Jizawi, Papa Diogop Ndiaye, Philipp Oertle, Gregory Zaugg, Marko Loparic, Marija Plodinec. Tissue nanomechanical signature predicts response to neoadjuvant chemotherapy in patients with breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6394.

Abstract 4951: Integrative multi-omic machine learning model predicts neoadjuvant immunotherapy response using molecular data and deep learning-derived features from digital pathology

Abstract Background: Over the past decade, there has been an exponential accumulation of digital patient data through molecular profiling and digitization of pathology slides. However, integrating this to advance diagnostics and cancer patient care remains a significant challenge. By integrating information from diverse modalities to capture aspects of the tumor microenvironment (TME) and immune landscape, we aim to improve patient stratification for immunotherapy. Methods: We collected data from baseline biopsies from patients with palpable melanoma stage III (n=195) who received neoadjuvant immunotherapy followed by surgical resection of largest lymph node metastasis. The different modalities included clinical information, whole-genome sequencing (WGS), RNAseq, laboratory tests of blood, haematoxylin and eosin (H&amp;E) images, and PDL1 immunohistochemistry (IHC) images. Cell detection and classification models were trained to identify tumor-infiltrating lymphocytes and tumor cells on H&amp;E whole-slide images (WSI), deriving spatial features to quantitatively describe the tumor-immune interaction. Various biomarkers, including tumor mutational burden, BRAF status, expression of inflammatory gene signatures, systemic neutrophil-to-lymphocyte ratio, and tumor-lymphocyte spatial measures, were collectively integrated using machine learning models (random forest, elastic-net regularized logistic regression, CatBoost, support vector machine (SVM), and an ensemble classifier combined from the other models) within a 5x5-fold nested cross-validation scheme to predict pathologic response. Results: Pathologic response to immunotherapy is associated with multi-omics biomarkers which were integrated using machine learning. The ensemble approach showed that when all modalities were combined a higher AUC (AUC=0.69, 0.61-0.77) could be achieved than for the clinical modality alone. RNA plus clinical emerged as the most predictive standalone modality with an AUC of 0.62 (0.50-0.75). The overall highest AUC was achieved using a SVM (AUC=0.72, 0.66-0.82). Conclusions: Immunotherapy efficacy depends on diverse tumor microenvironment components, which were comprehensively assessed through data integration. A multi-omic predictive model holds promise for refining personalized and effective immunotherapy strategies. Citation Format: Lindsay V. Leek, Vanessa Botha, Vipul A. Baxi, Jonas Teuwen, Hugo M. Horlings, Scott D. Chasalow, Joris van de Haar, Lodewyk F. Wessels, Auditi DebRoy, Emile E. Voest. Integrative multi-omic machine learning model predicts neoadjuvant immunotherapy response using molecular data and deep learning-derived features from digital pathology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4951.

Abstract 3607: Case study: Efficacy and persistence of autologous T cell therapy targeting SLC45A2 in uveal melanoma

Abstract Background: Metastatic uveal melanoma (UM) is an aggressive cancer, with a 1-year overall survival of &amp;lt; 50%. While the bispecific T-cell engager tabentafusp is approved for HLA-A2+ patients with gp100+ UM, there are limited treatment options for patients who do not express HLA-A2. We present a strategy and proof-of-concept for designing and manufacturing a tumor-selective endogenous T-cell therapy (ETC) for a patient with metastatic UM. Methods: PBMC were collected by apheresis in 2013 upon first diagnosis with uveal melanoma; 8 years later, following progression, cryopreserved PBMC were used to generate autologous antigen-specific T cells for adoptive therapy. The validated tumor antigen SLC45A2 was found to be overexpressed in the patient’s metastatic tumor based on RNA expression profiling. Peripheral blood derived SLC45A2-specific HLA-A2402-restricted central memory CD8+ T cells were generated via a process of in vitro priming, IL-21 treatment, tetramer-guided sorting and cell expansion. Clinical response was assessed via longitudinal CT imaging and ctDNA-based MRD monitoring. Persistence of transferred T cells was measured via serial flow cytometry and RNA-sequencing of PBMCs, along with TCR and RNA sequencing of tumor tissue collected post infusion. Results: A 39 year old male received SLC45A2-specific ETC therapy and checkpoint inhibitor treatment for advanced metastatic UM (GNAQ (Q209P), BAP1 (E398*, LOF). Bulk RNAseq data from baseline biopsies were queried for known tumor-associated antigens, and SLC45A2 was expressed at high levels. The patient experienced widespread disease stabilization with minimal toxicity. SLC45A2-specific CD8+ T cells persisted in circulation up to 181 days after the first infusion and 43 days after the second infusion, ranging from 6.7% - 1.5% of total circulating CD3 T cells. T cell clones from the infusion product included the dominating TCR subclone in tumor tissue collected 6 weeks post infusion, comprising 33% of the TCRá and 26% of TCRâ population. SLC45A2-specific T cells were identified in the tumor infiltrating lymphocytes in a separate lesion collected 10 months after the first infusion. A duodenum lesion progressed during treatment, and RNAseq demonstrated reduced expression of genes associated with HLA presentation and SLC45A2 and reduced TIL infiltration, suggesting tissue-specific immune editing of the tumor cell population. Conclusions: 1. Tumor-reactive antigen-specific T cells can be isolated and expanded for adoptive therapy using PBMCs cryopreserved for &amp;gt; 8 years. 2. Following infusion, peripheral blood and tumor profiling support the persistence of transferred T cells in a patient with metastatic uveal melanoma. 3. Disease stabilization in aggressive metastatic UM was achieved with minimal toxicity. Overall, our study provides evidence and rationale for utilizing autologous antigen-specific T cells for treating rare cancers. Citation Format: Shailbala Singh, Esther Ryu, Katie M. Campbell, Amber Smith, Suzanne Phillips, Luisa Soto, Ivy Lai, Gregory Lizee, Benjamin Vincent, Marshall Thompson, William Hoos, Sapna Patel, Cassian Yee. Case study: Efficacy and persistence of autologous T cell therapy targeting SLC45A2 in uveal melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3607.

Abstract 2467: Enhanced CD8+T-cell infiltration, PD-L1 expression, and T-cell repertoire expansion in patients with metastatic uveal melanoma responding to treatment with RP2 alone or in combination with nivolumab

Abstract Background: Metastatic uveal melanoma (MUM), typically an immune-excluded tumor, has few effective treatments and shows limited clinical response to immunotherapy. RP2 is an enhanced-potency oncolytic HSV-1 that expresses GM-CSF, an anti-CTLA-4 antibody-like molecule, and the fusogenic gibbon ape leukemia virus membrane R− glycoprotein (GALV-GP-R−). Here, we present the biomarker data of RP2 monotherapy and RP2 + nivolumab (nivo; anti-PD-1) in patients (pts) with MUM from an ongoing clinical trial (NCT04336241). Methods: Tumor biopsies and peripheral blood mononuclear cells (PBMCs) were collected pre-treatment and at Day 43 (D43). The tumor microenvironment (TME) was analyzed by immunohistochemistry (IHC). Systemic peripheral anti-tumor immunity was assessed by sequencing the CDR3β region of the T-cell receptor (TCR) using immunoSEQ Assay. HLA typing was obtained from patient history when available. Correlations between baseline tumor PD-L1 and CD8 expression, HLA type, prior treatment with ipilimumab (ipi)/nivo, and HLA status—vs clinical response status—were assessed. Results: As of August 2022, 17 pts with MUM were enrolled (RP2 monotherapy, n = 3; RP2 + nivo, n = 14). The majority of pts had previously received both anti-PD-1 and anti-CTLA-4 therapy (12/17, 70.6%), and 17.6% had received ≥3 prior lines of therapy. ORR for the 17 pts was 29.4% (5/17; all PRs; RP2 monotherapy, 1/3; RP2 + nivo, 4/14). Eight pts (2 PR, 3 SD, and 3 PD) had evaluable baseline and post-treatment biopsies for IHC, and 13 pts (4 PR, 4 SD, and 5 PD) had evaluable baseline and post-treatment PBMCs for TCR sequencing analyses. Of the 10 patients that achieved clinical benefit (PR/SD), IHC analysis of all available (n = 5, 2 PR, 3SD) paired biopsies demonstrated an increase in intra-tumoral PD-L1 expression, and 4 patients (2 PR, 2 SD) exhibited an increase in CD8+ T-cell infiltration into tumors at D43. No increase in either CD8+ T-cell infiltration or PD-L1 expression was observed at D43 in patients with PD. There was no correlation between HLA-A2*02:01 status or prior treatment with ipi/nivo and response. In addition, TCR sequencing revealed expansion of pre-existing TCRs (including a tumor antigen-specific clone targeting MART-1 in a responding patient) and generation of new T- cell clones, following RP2 + nivo. Conclusions: Preliminary RP2 + nivo data demonstrated meaningful antitumor activity in pts with MUM. Biomarker data indicated a conversion of the TME from an immune-excluded to an immune-infiltrated phenotype in responding patients following treatment with RP2 + nivo. Furthermore, systemic peripheral T-cell clonal expansion was noted. These results support further clinical development of RP2 + nivo in pts with MUM. Citation Format: Praveen K. Bommareddy, Alireza Kalbasi, Kevin J. Harrington, Anna Olsson-Brown, Tze Y. Chan, Pablo Nenclares, Isla Leslie, Mark R. Middleton, David M. Cohan, Konstantinos Xynos, Robert Coffin, Joseph J. Sacco. Enhanced CD8+T-cell infiltration, PD-L1 expression, and T-cell repertoire expansion in patients with metastatic uveal melanoma responding to treatment with RP2 alone or in combination with nivolumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2467.