Tumor Biopsies Research Articles

Deep learning-based risk stratification of preoperative breast biopsies using digital whole slide images

BackgroundNottingham histological grade (NHG) is a well established prognostic factor in breast cancer histopathology but has a high inter-assessor variability with many tumours being classified as intermediate grade, NHG2. Here, we evaluate if DeepGrade, a previously developed model for risk stratification of resected tumour specimens, could be applied to risk-stratify tumour biopsy specimens.MethodsA total of 11,955,755 tiles from 1169 whole slide images of preoperative biopsies from 896 patients diagnosed with breast cancer in Stockholm, Sweden, were included. DeepGrade, a deep convolutional neural network model, was applied for the prediction of low- and high-risk tumours. It was evaluated against clinically assigned grades NHG1 and NHG3 on the biopsy specimen but also against the grades assigned to the corresponding resection specimen using area under the operating curve (AUC). The prognostic value of the DeepGrade model in the biopsy setting was evaluated using time-to-event analysis.ResultsBased on preoperative biopsy images, the DeepGrade model predicted resected tumour cases of clinical grades NHG1 and NHG3 with an AUC of 0.908 (95% CI: 0.88; 0.93). Furthermore, out of the 432 resected clinically-assigned NHG2 tumours, 281 (65%) were classified as DeepGrade-low and 151 (35%) as DeepGrade-high. Using a multivariable Cox proportional hazards model the hazard ratio between DeepGrade low- and high-risk groups was estimated as 2.01 (95% CI: 1.06; 3.79).ConclusionsDeepGrade provided prediction of tumour grades NHG1 and NHG3 on the resection specimen using only the biopsy specimen. The results demonstrate that the DeepGrade model can provide decision support to identify high-risk tumours based on preoperative biopsies, thus improving early treatment decisions.

A phase I trial of intratumoral STX-001: A novel self-replicating mRNA expressing IL-12 alone or with pembrolizumab in advanced solid tumors.

TPS2696 Background: STX-001 is a multi-mechanistic lipid nanoparticle encapsulated synthetic self-replicating mRNA, engineered to express the IL-12 cytokine for an extended duration when administered intratumorally. A murine surrogate of STX-001 induces deep durable responses in multiple preclinical solid tumor models. This Phase 1 open-label, multi-center first-in-human dose-escalation trial evaluates the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary antitumor activity of STX-001 alone, or in combination with pembrolizumab in patients with treatment refractory advanced cancers. Methods: Approximately 30 adults ≥18 years of age with histologically confirmed advanced solid tumors that are refractory to standard treatments will be enrolled. The study will consist of two arms, an STX-001 monotherapy arm and an STX-001 + pembrolizumab combination arm, enrolling approximately 15 patients each. Key eligibility criteria include ECOG status 0 or 1, a tumor lesion amendable to injection, and confirmed prior disease progression. STX-001 will be administered every 3 weeks (q3w) for 3 doses and then every 6 weeks (q6w) for a further 3 doses. Tumor biopsies will be obtained at baseline and after the first STX-001 administration. Primary endpoints will include safety and maximum tolerated dose (MTD), with secondary endpoints encompassing pharmacokinetics and preliminary efficacy as measured by RECIST 1.1. To determine the MTD, this study will employ the Bayesian optimal interval (BOIN) design, with the 3 + 3 design run-in and a recommended phase 2 dose (RP2D) will be determined. Tumor response will be assessed using RECIST 1.1 criteria. Exploratory pharmacodynamic analyses will assess tumor-infiltrating lymphocytes and STX-001 mRNA in baseline and on-treatment biopsies, evaluate inflammatory cytokine profiles in plasma, determine immune activation in circulating immune cells, and measure circulating tumor DNA (ctDNA) for molecular response assessment. Clinical trial information: NCT06249048 .

A first-in-human study of IK-595, an oral MEK/RAF molecular glue, in patients with RAS- or RAF-altered advanced solid tumors.

TPS3185 Background: Alterations in the RAS/RAF/MEK/ERK pathway are the most common drivers of oncogenesis. MEK is a clinically validated cancer target and despite FDA approval of several MEK inhibitors, their clinical utility has been limited to BRAF V600 mutant cancers and NF1 mutant neurofibromas mostly due to early emergence of resistance and low therapeutic indices. IK-595, a potent novel MEK-RAF molecular glue, is being developed to overcome these limitations. IK-595 traps MEK in an inactive complex with all RAF isoforms and blocks RAF-dependent MEK phosphorylation, thereby alleviating CRAF-mediated MEK reactivation that hinders the efficacy of approved MEK inhibitors in RAS/RAF-driven tumors, in addition to kinase independent CRAF activity. IK-595 exhibits potent single agent activity in a wide range of in vivo cancer models harboring various RAS/RAF alterations, including, but not limited to, lung, pancreatic, colorectal cancer (CRC), melanoma, and AML. The preclinical pharmacokinetic profile of IK-595 also enables flexible dosing schedules resulting in a broader therapeutic window. Methods: This is a phase 1, first-in-human, open-label, multicenter study to evaluate IK-595 as monotherapy in patients with RAS- or RAF-altered advanced solid tumors for whom there are no other further treatment options known to confer clinical benefit. Dose escalation uses a Bayesian Optimal Interval Design (BOIN) in patients with advanced and unresectable, or metastatic solid tumors with confirmed RAS/RAF gene alterations. Backfilling of cleared dose levels with key target indications will initiate upon achievement of efficacious plasma exposures. Dose expansion will occur in genetically defined cohorts, for example NRAS-mutant CRC and malignant melanoma, as well as BRAF non-V600 and KRAS mutant tumors using a Simon 2-stage adaptive design. IK-595 will initially be administered on an intermittent dosing schedule in 30-day cycles. Additional dosing schedules may be explored. Primary objectives of the study are to evaluate safety and tolerability of IK-595 and to determine the recommended phase 2 dose (RP2D) and/or maximum tolerated dose (MTD). Secondary objectives include evaluation of preliminary antitumor activity by RECIST 1.1, pharmacokinetic (PK) parameters, and pharmacodynamic effects of IK-595 on pERK in paired tumor biopsies. Key exploratory endpoints include changes in pERK in peripheral blood cells, changes in pERK target genes in tumor biopsies, and assessment of candidate baseline response biomarkers. The study began in December 2023 and enrollment in Cohort 1 was completed with no DLTs; dose escalation continues to enroll. Clinical trial information: NCT.

A phase 2, multicenter study of TILs treatment in advanced tumors with alterations in the SWI/SNF complex: The TILTS study.

TPS2674 Background: Tumors associated with SWI/SNF complex (SWI/SNFc) mutations, mainly SMARCA4 and SMARCB1 loss, are a heterogeneous group of malignancies with rhabdoid features that typically affect young patients (pts). These are aggressive malignancies with poor prognosis for which no standard treatment is available. Despite not having a high tumor mutation burden, tumor infiltrating lymphocytes (TILs) are usually present in high numbers. The biologic reasons for this feature are not clearly understood but might be associated to changes in gene expression due to aberrant chromatin remodeling. However, these TILs indicate that tumor antigens are recognized by lymphocytes unveiling a vulnerability that can be exploited by immunotherapy. The objective of the TILTS study is to develop a personalized adoptive cell therapy using TILs in pts affected by these tumors. Methods: Single arm, multi center, phase 2 study of TILs in pts with advanced tumors associated with SWI/SNFc mutations. Pts are treated at 3 centers in Spain: Catalan Institute of Oncology (ICO), Barcelona, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, and Centro Integral Oncológico Clara Campal (HM CIOCC), Madrid. Primary endpoint is overall response rate (ORR) by RECIST 1.1. Secondary endpoints include toxicity evaluation, duration of response (DOR), progression-free survival (PFS) or overall survival (OS). After informed consent is obtained, tumor resection is performed. Total volume of tumor resected should be at least 1.5 cc to assure TIL isolation. Eligible pts enter the treatment phase. TILs are produced under GMP conditions. During the TILs manufacturing process, pts are allowed to receive standard treatment if clinically indicated. Before TIL infusion, pts receive non-myeloablative preconditioning lymphodepletion with daily intravenous (IV) cyclophosphamide (60 mg/kg; IV x2 doses) and daily fludarabine (25 mg/m2; IV x5 doses). Infusion of autologous TILs is given on Day 0 followed by administration of IL-2 at 600,000 international units (IU)/kg every 8-12 hours for a maximum of 6 doses. After 4 weeks, a new tumor biopsy is optional. First image evaluation is performed after 8 weeks from TIL infusion. Pts without progression enter the follow-up phase. An ancillary translational study will explore mechanisms of immunogenicity, antigen recognition, TILs anti-tumor activity, and changes in the stool microbiome and specific TCR population during treatment. Also, tumor immune microenvironment will be analyzed. Clinical trial information: 2023-504632-17-00 . [Table: see text]

A phase II trial to evaluate the epithelial-to-mesenchymal (EMT) inhibitor sotevtamab combined with docetaxel in patients with metastatic non-small cell lung cancer following failure of primary chemoimmunotherapy.

8577 Background: Sotevtamab is an investigational humanized monoclonal antibody that binds to tumor associated secreted clusterin (TA-sCLU). TA-sCLU is a potent inducer of the epithelial-to-mesenchymal transition (EMT), a process known to contribute to tumor invasion, metastasis, chemoresistance and immune evasion. Sotevtamab abrogates the EMT-promoting activity of TA-sCLU by inhibiting its ability to be internalized in cancer cells. Methods: An open-label, single-arm, multi-center Phase II clinical study of sotevtamab administered in combination with docetaxel was performed in subjects with metastatic non-small cell lung cancer who had experienced progression following frontline immunochemotherapy. 35 subjects were enrolled from March 2021 to November 2022 and the study was completed in December 2023. Sotevtamab was administered at a dose of 12 mg/kg once weekly on Days 1, 8 and 15 combined with docetaxel at a dose of 75 mg/m2 once every 3 weeks on Day 1. One cycle of treatment consisted of 21 days. The primary objectives were to determine the objective response rate (ORR) and the safety and tolerability of the combination. Tumor biopsies were performed prior to study initiation and after two cycles of therapy for pharmacodynamicevaluation. Results: As per interim data obtained from a rolling database lock performed in February 2023, the mean subject age was 63 and 22 patients (63%) were female. Of the 35 subjects, 28 were diagnosed with adenocarcinoma, 6 with squamous cell carcinoma and 1 with adenosquamous carcinoma; 11 were ECOG 0, 22 ECOG 1 and 2 ECOG 2. Six subjects with adenocarcinoma had a partial response for an ORR of 17.1%. Stable disease (SD) was experienced in an additional 10 subjects (9 adenocarcinomas and one squamous cell carcinoma) for an SD rate of 28.6%. The observed responses were sustained with a median duration of over one year (405 days). The estimated one-year survival rate was 33.9%. The most frequent adverse events were fatigue, infusion related reaction (IRR), diarrhea, nausea and anemia. The incidence of IRR was significantly decreased following the implementation of a premedication protocol. Analysis of paired tumour biopsies revealed in certain patients that sotevtamab induced a strong intratumoral immune response with the formation of Tertiary Lymphoid Structures (TLS). Various pharmacodynamic evaluations are being performed to better define the profile of responding patients. Conclusions: This phase II study showed promising response and overall tumor control. Duration of response was particularly encouraging and relevant to further exploration. The sotevtamab and docetaxel combination may enhance immune-mediated anti-tumor response through induction of TLS. Data from the final database lock will be presented. Clinical trial information: NCT04364620 .

Phase II clinical trial of PLX038 in patients with platinum resistant ovarian, primary peritoneal and fallopian tube cancer.

TPS5630 Background: Platinum-resistant ovarian cancer (PROC) portends a poor prognosis and, although treatments are available, response rates are low. Previous studies have demonstrated that DNA topoisomerase I (TOP1) inhibitors exhibit clinical activity in PROC. Irinotecan also has a 15-25% response rate in some studies of platinum-resistant epithelial ovarian cancer but does not have FDA approval for this indication. Additional studies in preclinical models suggest that TOP1 poisons are more active if administered at low doses on prolonged schedules. PLX038 is a long-acting prodrug of the potent TOP1 inhibitor SN-38. In PLX038, SN-38 is covalently conjugated to circulating polyethylene glycol and is slowly released at a constant rate to provide the active agent with a long half-life, a low Cmax and very high exposure – important facets for optimal safety and efficacy of this drug. Further, in preclinical studies the nanoparticle prodrug accumulates and is retained in tumors, where it slowly releases the SN-38. Methods: This single arm, phase 2 clinical trial is open at Mayo Clinic in Rochester, MN. The primary endpoint is overall response rate and secondary endpoints include progression-free survival and assessment of tolerability of PLX038. Correlative goals include i) measurement of TOP1-DNA covalent complexes in tumor biopsies and circulating tumor cells to assess successful target engagement; ii) assessment of homologous recombination status and SLFN11 expression for correlation with tumor response rate; and iii) pharmacokinetics of SN-38 and SN-38G as well as their association with GI toxicity. Assessment of gut microbiota and association with GI toxicity profile are also being investigated. Eligible patients include women with platinum resistant high grade serous ovarian, primary peritoneal, and fallopian tube cancer who have received fewer than two prior chemotherapy regimens in the platinum-resistant setting. All patients must have an ECOG performance status of 0, 1, or 2 and adequate bone marrow, renal, and hepatic function. As of January 31, 2024, 12 of planned 37 patients have enrolled. Clinical trial information: NCT05465941 .

TBCRC 048 (olaparib expanded) expansion cohorts: Phase 2 study of olaparib monotherapy in patients (pts) with metastatic breast cancer (MBC) with germline (g) mutations in PALB2 or somatic (s) mutations in BRCA1 or BRCA2.

1021 Background: TBCRC 048 is an investigator-initiated proof of principle phase II trial that demonstrated responses with monotherapy olaparib in MBC pts with g PALB2 or s BRCA mutations. Here we report results of the expansion cohorts for additional pts with g PALB2(Cohort 1a) or s BRCA (Cohort 2a) mutations. Methods: 24 MBC pts with g PALB2m and 30 pts with s BRCAm were enrolled in the expansion cohorts from Sept 2020 to Oct 2023.Eligibility included: MBC with measurable disease; documented g PALB2m or s BRCAm (with normal g BRCA testing); progression on < 2 metastatic chemotherapy regimens. Prior PARP inhibitor or progression on platinum was not allowed. Patients received olaparib 300 mg bid until progression or unacceptable toxicity. The null hypothesis for each expansion cohort [≤ 30% objective response rate (ORR)] would be rejected if > 13 responses were seen. Secondary endpoints include clinical benefit rate (CBR) at 18 weeks, progression-free survival (PFS), duration of response (DOR) and whether the mutant allele frequency (MAF) is significantly higher in responders than in non-responders. Enrollment to the g PALB2 cohort was closed early due to slow enrollment. PFS and DOR were estimated using the Kaplan-Meier method. Association between MAF and response status was assessed using Wilcoxon rank sum test. Results: In Cohort 1a (g PALB2, n=24), median age was 52.5 years (range: 26-86). 19 pts had ER+ HER2-negative, 2 HER2-positive, and 3 triple-negative breast cancer (TNBC). There were 18 confirmed responses for ORR of 75% (80% CI: 60.2%-86.3%); CBR at 18 weeks was 83.3% (90% CI: 65.8%-94.1%). Median PFS was 9.6 months (90% CI: 8.3-12.4). Median DOR was 7.1 months (90% CI: 5.6-11.0). In Cohort 2a (s BRCA1/2, n=30) 15 pts had s BRCA1m and 15 s BRCA2m. 23 pts had ER+ HER2-negative, 3 HER2-positive, and 4 TNBC. There were 11 confirmed responses for ORR of 36.7% (80% CI: 24.8%-50%). CBR was 53.3% (90% CI: 37%-69.2%) and median PFS was 5.6 months (90% CI: 3.0-8.3). Median DOR was 12.4 months (90% CI: 4.3-not reached). One additional pt with a s BRCAm had a PR, which was not confirmed. Clinical and molecular factors associated with response to olaparib are being evaluated. MAF was available and evaluable for 33 of the 46 pts in Cohorts 2 plus 2a who had s BRCAm identification by tumor biopsy. The mean MAF was 43% in responders and 39 % in non-responders (p=0.7), which was not significantly different. Conclusions: The notable ORR (75%) with olaparib in this second cohort of women with MBC and g PALB2m was again demonstrated.Olaparib activity inMBC pts with s BRCAm was also confirmed, though identifying predictors of response for these pts is of critical importance to distinguish those more likely to respond to PARP inhibition. Clinical trial information: NCT02032823 .

Pharmacokinetic analysis of OMO-103 in patient tissues with advanced solid tumors.

e15168 Background: MYC is a pleiotropic transcription factor aberrantly expressed in up to 70% of human cancers. OMO-103 (Omomyc) is a 91-amino-acids-long polypeptide that derives from the B-HLH-LZ domain of human MYC, containing four amino acid substitutions. It is capable of forming homos and heterodimers with MYC and with MAX and blunt MYC activity by preventing its access to target DNA sequences (E-boxes) and replacing it by inactive complexes. Previous in vivo preclinical experiments showed that Omomyc blocks MYC-driven transcription and proliferation, induces apoptosis and recruitment of intratumoral immune infiltrates, significantly abrogating tumor progression and reducing tumor grading. Here, we present PK results from the first-in-human trial (NCT04808362) of OMO-103 in patients with advanced solid tumors. Methods: Patient eligibility The study included histologically or cytologically proven advanced solid tumors for which there was no curative therapy. Patients had to demonstrate measurable disease according to RECIST v.1.1 criteria as demonstrated by CT/magnetic resonance imaging and documented progression on or following the last line of therapy. Description and dose selection OMO-103 was administered by weekly I.V. infusion over 30–45 min, one treatment cycle corresponding to three infusions. Patients were treated until progression. The starting dose of 0.48 mg kg−1 was determined based on nonclinical toxicology and efficacy studies (anticipated pharmacologically active dose) and subsequent conversion to a human equivalent dose. Pharmacokinetic assays A targeted mass spectrometry (MS) assay for the absolute quantification of 4 Omomyc proteotypic peptides was developed to quantify functional OMO-103 in tumor tissue. LLOQ and linear range of the panel was determined by spiking in dilution series of recombinant OMO-103 protein into tumor tissue lysates. Finally, in the phase I trial, we used the panel for the quantification of OMO-103 in FFPE tumor biopsies from 12 patients who received i.v. injection of OMO-103. Results: MS Data show that 2 h after i.v. administration, higher concentrations of the drug are reached in the tumors compared with serum and persist there with at least one order of magnitude higher concentration than in serum 72 h after administration in preclinical models. Functional Omomyc protein could be quantified in all 12 clinical tumor biopsies from treated patients and PK results confirmed previous observations in preclinical models. where Omomyc exhibits higher tissue concentration and prolonged residency compared to plasma. Conclusions: We demonstrate the utility of targeted MS assay for precise quantification of therapeutic (mini)proteins in clinical tissue samples. Thanks to its multiplexing capability, up to 60 peptides (epitopes) can be monitored simultaneously which enables high sequence coverage and profiling of additional PD or other supporting biomarkers. Clinical trial information: NCT04808362 .

RNA-Seq based gene expression profiling of baseline and on-treatment breast tumors to predict response to HER2-directed therapy, without chemotherapy (TBCRC026).

530 Background: Robust biomarkers are needed to personalize treatment in early stage HER2-positive breast cancer. The TBCRC026 trial (n=83) demonstrated that early metabolic changes on FDG-PET/CT [>40% decline in SULmax at day 15 post treatment initiation (C1D15); C1D15 SULmax] were associated with response to neoadjuvant trastuzumab/pertuzumab (HP), without chemotherapy, in an ER-negative, HER2-positive cohort (NCT01937117). We investigated the association of RNA sequencing (RNAseq)-based gene expression signatures (GES) at baseline and on-treatment (C1D15), with early metabolic change on PET/CT and clinical outcomes. Methods: RNAseq (664 GES) was performed on baseline (n=56) and C1D15 (n=31) tumor biopsies (25 paired samples available). Association with pCR following HP (secondary), PET/CT parameters and survival (exploratory) was studied. Gene expression changes between baseline and C1D15 samples were tested by Wilcoxon signed-rank test. Association between GES and PET/CT parameters and GES with pCR were evaluated using logistic regression models. Cox regressions were performed to study the association between PET/CT SULmax at C1D15 and a B cell signature and relapse-free survival (RFS). The likelihood ratio test was used to compare the prognostic ability of two nested Cox models. Results: Both RNAseq and clinical outcomes were available in 53/83 patients. HER2-enriched (HER2-E) intrinsic subtype comprised 71% (40/56) of cases at baseline and 61% (19/31) at D15; basal subtype for 27% (15/56) and 39% (12/31), respectively. pCR rate was 19% (10/53) with all but one exhibiting HER2-E subtype. One basal-like sample underwent pCR, with downregulation of HER2 amplicon and IgG signatures slightly more prominent. Gene expression changes from baseline to C1D15 were analyzed; ERBB2was downregulated after HP (p = 0.007), B cell signatures, CD4, CD8, natural killer cells and Treg cells were significantly upregulated at C1D15. GES associated with 40% decline in SULmax at C1D15 included ERBB2 amplicon genes ( ERBB2, GRB7) and correlation to the HER2-E subtype, whereas basal-like signatures were significantly associated with lack of response on PET at C1D15. Univariate logistic regression analysis suggested that FOS-JUN, fibroblast and B cell GES at baseline were significantly associated with pCR (p=<0.05). Finally, the addition of a B cell signature improved the prognostic value of C1D15 SULmax on PET/CT for RFS (p < 0.05). Conclusions: In this unique cohort with ER-negative, HER2-positive breast cancer treated with neoadjuvant HP without chemotherapy, HER2-E tumors and those with increased immune signaling were more likely to respond to HER2-directed therapy. Combining C1D15 SULmax on PET/CT and a B cell signature provided improved prognostic information and should be further explored as candidate biomarkers in this setting. Clinical trial information: NCT01937117 .

Ex vivo assessment of cellular mass response for personalized therapy selection of hyperthermic intraperitoneal chemotherapy (HIPEC) agents.

3132 Background: Despite progress in the development of HIPEC protocols for the treatment of peritoneal carcinomatosis, agent selection remains largely empiric with few biomarkers for guiding treatment. Ex vivo assessment of drug response using single-cell mass measurements offers a promising option for therapy selection. Previously, we have shown that mass response testing (MRT) is a malignancy- and drug-agnostic means of assessing drug response (1) and can predict a patient’s clinical response to therapy in a range of solid and hematological malignancies (2). Methods: Tissue specimens were collected from patients with peritoneal carcinomatosis as part of an ancillary study for a HIPEC clinical trial (NCT04847063) to explore the feasibility of performing MRT with these specimen types. Briefly, after overnight shipment of viable tumor tissue, tumor cells were isolated and treated with various therapies ex vivo. Single-cell mass distributions of vehicle and drug-treated populations were compared to determine the functional activity of each agent. Results: MRT was attempted for 60 patients with metastatic disease, 10 of whom had peritoneal carcinomatosis and ultimately received HIPEC. The HIPEC cases included histologies such as peritoneal mesothelioma (n=4), colorectal cancer (n=3), ovarian cancer (n=2), and small bowel adenocarcinoma (n=1). In total, 8 out of 10 peritoneal specimens had a sufficiently high tumor cell count, viability, and purity to perform MRT. These specimens displayed clear and statistically distinguishable mass response patterns of response and non-response to several different agents commonly used for HIPEC treatment such as cisplatin, oxaliplatin, doxorubicin, and mitomycin C. Study design:These feasibility results serve as the foundational data for launching a single-site phase II interventional study at the NCI’s Center for Cancer Research. The study will evaluate the potential benefit of personalized treatment regimens determined by MRT for patients with peritoneal carcinomatosis, particularly mesothelioma, a context where therapeutic options have relative equipoise in clinical efficacy. Tumor biopsies will be obtained via laparoscopy prior to HIPEC and submitted to a CLIA-certified lab for MRT to assess the responses of various clinically acceptable agents. The HIPEC regimen will be selected based on these MRT results returned within two days of sample collection. Enrolled patients will then undergo cytoreduction and HIPEC, and progression-free and overall survival will be monitored. As a single-arm, non-randomized trial, patient responses will be compared with a matched synthetic control to assess the impact of MRT on efficacy of HIPEC regimens. Conclusions: MRT is feasible for peritoneal carcinomatosis tissues, with future studies focusing on its role in guiding HIPEC treatment. 1. Nat Comm Bio,2022. 2. JCO PO, 2024. Clinical trial information: NCT04847063 .

YB-800, a monoclonal antibody targeting the human neuronal pentraxin receptor (NPTXR), as a potential candidate for the design of a first in class antibody drug conjugate (ADC) as novel therapeutic intervention in gastro-intestinal cancers.

e15022 Background: The human neuronal pentraxin receptor (NPTXR) gene encodes a type II transmembrane protein that functions as a trans-synaptic organizer and anchors neuronal pentraxin complexes to plasma membranes. Beside a subset of neuronal cells (Hippocampus and Cerebral Cortex), expression of NPTXR is not detected in all other tissues [ The Human Protein Atlas database]. In recent studies [Kanda et al. (2020) Mol. Cancer. doi: 10.1186/s12943-020-01251-0], transcriptome and bioinformatics analysis of gastric cancer (GC) tissues from patients with or without metastasis have revealed that NPTXR expression was associated with disease progression. NPTXR expression was also correlated negatively with survival in GC patients. It appears that NPTXR does not have a major physiological function; e.g., NPTXR−/− mice showed no abnormalities in reproduction, development, metabolism, or motor function. NPTXR is expressed in a number of GI cancers, i.e., gastric, esophageal, colorectal, pancreatic, bladder, liver, as well as breast and thyroid cancer. YB-800 is a fully humanized monoclonal antibody against NPTXR (identified by in silico analysis). Methods: The present studies were conducted to provide a rationale for the design of a YB-800-based antibody drug conjugate (ADC) for therapeutic intervention in oncology. Hence, YB-800 binding to and internalization in selected tumor cells, as well as immunohistochemistry (IHC) in tumor biopsies, were evaluated. Results: Taken together experimental data confirm that: (i) YB-800 binds to a new target (NPTXR) on selected tumor cells; confirmed by FACS analysis; (ii) IHC analysis in tumor samples demonstrates specific immunoreaction in bladder, gastric, prostate, hepatocellular carcinoma, colorectal cancer and cervical cancer, but not in adjacent healthy tissues; and (iii) once YB-800 binds to NPTXR, the conjugate is internalized in selected tumor cells in a time-dependent manner. Conclusions: In conclusion, YB-800 represents a first in class ADC candidate that could be used as novel treatment for gastro-intestinal cancers. Hence, as initial proof of concept, tesirine (DNA intercalating agent) and deruxtecan (topoisomerase I inhibitor) containing protease-sensitive linkers were coupled to YB-800 by stochastic maleimide conjugations to interchain cysteines. Initial results with YB-800-based ADCs will be discussed.

A phase Ib/II study of an anti-CD137 agonist antibody ADG106 in combination with weekly paclitaxel and dose-dense doxorubicin/cyclophosphamide.

e14507 Background: ADG106 is a fully human agonistic anti-CD137 IgG4 monoclonal antibody which modulates the tumor microenvironment and has demonstrated increased efficacy when added to chemotherapy in preclinical models. We studied the combination of ADG106 with chemotherapy. Methods: We conducted a phase Ib trial in patients with advanced solid tumors to determine the recommended phase 2 dose (RP2D) of ADG106 + weekly P (paclitaxel 80mg/m2) or ddAC (doxorubicin 60mg/m2, cyclophosphamide 600mg/m2 Q2W with pegfilgrastim), followed by a phase II trial of neoadjuvant ADG106 + weekly Px12→ADG106 + ddACx4→surgery in stage I-III HER2 negative breast cancer patients. In phase Ib, one dose of single agent ADG106 was administered followed 2 weeks later by ADG106 + ddAC (Cohort 1) or ADG106 + weekly P (Cohort 2). Dose levels (DL) of ADG106 were 50mg (DL-1), 100mg (DL1), 200mg (DL2). Serial tumor biopsies were performed at baseline, after single agent ADG106 and at disease progression in phase I, and at baseline, after single agent ADG106, after cycle 1 ADG106 + P, and at surgery in phase II for translational studies. Results: 11 patients were enrolled into Phase Ib with median 3 (range 2-11) prior lines of palliative systemic therapy. ADG106 + ddAC (n=2 at DL1) was deemed intolerable with 1 patient experiencing G4 neutropenia and the other G3 infection; thus ADG106 was not added to ddAC in phase II. No DLTs were observed in all patients receiving ADG106 + P (n=6 at DL1; n=3 at DL2); ADG106 RP2D was declared at 200mg + P. In this cohort, the most common all-grade AEs were neutropenia (n=6), peripheral neuropathy (n=6) and fatigue (n=6); significant ≥G3 AEs were infection (n=2) and G3 neutropenia (n=6). 5/11 (45%) patients in phase I achieved clinical benefit (CBR; PR=2, SD=3) which is clinically meaningful as 9/11 (82%) had prior taxane exposure. 18 of the planned 30 patients have been enrolled into Phase II (ADG106+weekly P→ddACx4→surgery); 10 have completed study treatment and 5 have undergone surgery. While on ADG106 + P, 4 patients experienced G3 adverse events (AEs): neutropenia (n=3), hypophosphatemia (n=1), fever (n=1). Most common G1-2 AEs were ALT elevation (n=4), acneiform rash (n=3) and peripheral neuropathy (n=3). While on ddAC alone, all AEs were low grade except for 1 patient who had G3 pneumonitis from Pneumocystis Jiroveci Pneumonia. 26 sets of matched tumor biopsies have been collected (9 in phase I; 17 in phase II) and will be tested for a panel of 40 markers by multiplex IHC, including CD137, PD-L1, and CD3/4/8. Conclusions: ADG106 when combined with ddAC exacerbates neutropenia and is not tolerable despite prophylactic pegfilgrastim. The RP2D of ADG106 in combination with P is 200mg and is safe and tolerable; manageable G3 neutropenia was the most common AE. There are no new safety signals thus far in Phase II. Further efficacy analyses and studies on tumor immune markers are ongoing. Clinical trial information: NCT05275777 .

Safety, efficacy, and biomarker results from an open-label, multicenter, phase 1 study of RP2 alone or combined with nivolumab in a cohort of patients with uveal melanoma.

9511 Background: Uveal melanoma is the most common primary intraocular tumor in adults and has a high risk of liver metastasis. Effective treatments for metastatic uveal melanoma (MUM) are limited, as MUM responds poorly to immune checkpoint inhibition. RP2 is an enhanced-potency oncolytic HSV-1–expressing human GM-CSF, a fusogenic glycoprotein (GALV-GP-R−), and an anti–CTLA-4 antibody-like molecule. We present safety, efficacy, and biomarker data for RP2 monotherapy and RP2 +nivolumab (nivo; anti–PD-1) in patients (pts) with MUM (NCT04336241). Methods: Pts ≥18 years old with advanced or metastatic non-neurologic solid tumors (including MUM) who progressed on, or could not tolerate, standard therapy were included in the clinical trial; pts had ≥1 measurable and injectable tumor (≥1 cm). After determination of the recommended phase 2 dose of intratumoral RP2 (1×106 PFU/mL once, then ≤7 doses at 1×107 PFU/mL; ≤10 mL total/treatment day), pts received RP2 Q2W as monotherapy or in addition to nivo (240 mg Q2W/480 mg Q4W). Responses were assessed per modified RECIST v1.1.Tumor biopsies and peripheral blood mononuclear cells were collected pre-treatment and at day 43 and were analyzed by immunohistochemistry (IHC) and/or sequencing of the CDR3β region of the T-cell receptor (TCR) by immunoSEQ. Results: A total of 17 pts with MUM were enrolled (RP2 monotherapy, n = 3; RP2 + nivo, n = 14). Most pts had received both anti–PD-1 and anti–CTLA-4 therapy (12/17 [70.6%]), and 3/17 (17.6%) had received ≥3 prior lines of therapy. The ORR was 29.4% (5/17; all PRs; RP2 monotherapy, 1/3; RP2 + nivo, 4/14). The DCR (CR + PR + SD) was 58.8% (10/17). The median (range) duration of response at the data cutoff was 11.5 (2.8–21.2) months, with some responses and disease stabilizations ongoing. The most common overall grade 1–2 treatment-related AEs (TRAEs; ≥20% overall) were pyrexia, chills, fatigue, hypotension, and pruritus. The only grade 3 TRAE in > 1 pt was hypotension (2 pts receiving RP2 + nivo); no grade 4/5 TRAEs occurred. Evaluable baseline and post-treatment biopsies were used for IHC (n = 8) and TCR sequencing analyses. Paired biopsies from pts with clinical benefit (n = 5; 2 PR, 3 SD) showed an increase in tumor PD-L1 expression by IHC analysis, and 4 of these pts (2 PR, 2 SD) exhibited an increase in CD8+ T-cell infiltration into tumors. TCR sequencing following treatment with RP2 + nivo revealed expansion of pre-existing TCRs and generation of new T-cell clones. Conclusions: RP2 alone or combined with nivo demonstrated a favorable safety profile and meaningful antitumor activity in pts with previously treated MUM. Biomarker data indicated immune cell infiltration and increased PD-L1 expression in tumors and changes in the peripheral T-cell repertoire following RP2 ± nivo therapy. Based on these results, a randomized, controlled clinical development plan is being planned. Clinical trial information: NCT04336241 .

Real-world experience of larotrectinib in children, adolescents and young adults with TRK fusion solid tumors in France.

10056 Background: Larotrectinib is an FDA and EMA approved TRK inhibitor for TRK fusion solid tumors in patients with locally advanced or metastatic disease, or where surgical resection is likely to result in severe morbidity. Here we report the real-world activity and safety data on compassionate use and post-marketing authorization of larotrectinib collected in the SACHA-France study (NCT04477681), following the French Health Technology Assessment institution (HAS) request. Methods: All larotrectinib prescriptions made in France outside clinical trials since April 2019 for patients’ < 25 years-old were registered in the SACHA-France study. Safety and activity data were collected, with data cut-off of 23/01/2024. SACHA-France is open in all 31 French Society of Pediatric Oncology (SFCE) centers, it is approved as a real-world data source by the HAS and supported by the French National Agency for the Safety of Medicines and Health Products (ANSM). Results: 21 patients were included (4 compassionate use, 17 post-marketing authorization). Main cancer types were soft-tissue sarcomas (n=13, of them 7 infantile fibrosarcoma), followed by central nervous system (CNS) tumors (n= 7), and other solid extra-CNS tumors (n=1). All patients except one had a TRK fusion tumor: NTRK3 (n=10), NTRK2 (n=6, all CNS tumor) and NTRK1 (n=4). Median age at start of larotrectinib was 2.8 years (range: 0.2 -21.1). Ten patients had received no prior systemic therapy. Main reasons to start larotrectinib were to avoid mutilating surgery (n=9) and disease progression (n=9). Best objective response was reported as partial response in 13 out of 19 patients with evaluable disease (10/12 patients with soft tissue sarcomas, 2/6 patients with CNS tumors), with median time to response of 57 days. Of them, five patients with soft tissue sarcomas achieved a complete response after non mutilating surgery. Median treatment duration was 219 days (range: 10-1368, 5 patients still on therapy). Seven patients with soft tissue sarcomas stopped larotrectinib, after a median duration of 242 days (range: 122-1190), three of them after tumor surgery; none presented with tumor recurrence (follow-up: 350 days; range 40-636). At data cut-off, 8 patients had disease progression on-therapy (5/7 CNS tumors, 3/13 soft tissue sarcomas), with a NTRK resistance mutation identified in 2 out 3 patients with tumor biopsy. Adverse drug reaction (ADR) were reported in 2/21 patients (9%), including a grade 2 weight gain and a grade 3 neutrophil count decreased (1 patient each). Both ADRs were expected and required neither corrective treatment nor action on larotrectinib. Conclusions: Our real-world data confirm the favorable safety profile of larotrectinib with rapid and durable tumor-agnostic efficacy.

Altering the gut microbiome and TME in advanced liver cancers: A phase II study of nivolumab, tadalafil, and oral vancomycin in refractory HCC or liver-dominant metastatic CRC or PDAC.

e14642 Background: The gut-liver axis shapes the environment that promotes liver disease. In murine models of liver cancer, our group showed that altering gut microbiome with oral vancomycin can induce an antitumor effect by modifying bile acids (BA) that then recruit natural killer T cells (NKTC). However, these NKTC were met by an immunosuppressive counter-regulatory response where myeloid-derived suppressor cells (MDSC) accumulated, impairing their cytotoxicity. Tadalafil, a PDE5 inhibitor, can suppress these MDSC in the TME. The aim of this study was to examine if the immunomodulatory effects of oral vancomycin and tadalafil can enhance nivolumab activity in advanced primary liver cancer or liver metastases. Methods: This is a phase II study of adult patients (pts) with refractory hepatocellular carcinoma (HCC) or liver-dominant metastatic colorectal (mCRC) or pancreatic (mPDAC) cancers. Pts received IV nivolumab 480mg on D1, oral vancomycin 125mg every 6 hours on D1-21, and tadalafil 10mg once daily in 28d cycles until disease progression or unacceptable toxicity. Primary endpoint was best overall response (BOR) according to RECIST v1.1. Secondary endpoints included safety/tolerability and mOS. Correlative studies were performed on paired stool, blood, and tumor biopsies. Results: From 6/2019 - 7/2021, 22 heavily pretreated pts were enrolled: 6 HCC, 9 PDAC, 7 CRC. Median age was 63y (41-82), and 27% were female. Molecular testing showed MSS, TMB low to intermediate (1.57-13.35), and frequent mutations in KRAS and TP53. The BOR was SD (3pts, 18.75%), followed by PD (13pts, 81.25%); there were no PR or CR (ORR = 0%). Six pts had symptomatic deterioration prior to restaging scans. At a median follow-up of 4m (0.9-23.0m), all 22 pts had died of progressive disease with mOS of 4m. When stratified by site of origin, mOS was 9.5m (95%CI: 1.3-21.9m) in HCC and 3.6m (95%CI: 1.9-6.6m) in liver metastases (log-rank test, p=0.27). The most common grade 3-4 trAEs were electrolyte disturbances and anemia. The stool microbiome composition of Bacteroides species did not change with treatment as detected by shotgun sequencing. Plasma secondary BA, measured by the mixed meal test, decreased with treatment (p<0.05, n=18, two-way ANOVA). The classical to non-classical monocytes ratio increased with treatment in flow cytometry analysis of PBMC immune cells (p<0.05, n=14, one-way ANOVA). Transcriptomic analysis of treated liver tumor biopsies showed an increase in BA metabolism. Conclusions: Although well tolerated, the combination of oral vancomycin and tadalafil with nivolumab did not produce any meaningful clinical responses. Correlative studies suggested enhanced activation of BA metabolization, but TME immune profiling did not reveal substantial changes in regulatory suppressor cells or NKTC activity. Clinical trial information: NCT03785210 .

Prediction for major pathologic response after neoadjuvant tislelizumab combined with chemotherapy in patients with locally advanced esophageal squamous cell carcinoma by RNA sequencing: A single-arm, phase II trial.

4078 Background: Although neoadjuvant chemoradiotherapy is evolved into standard-of-care treatment in locally advanced esophageal cancer (EC) patients (pts), nearly half of pts experience relapse and death within 5 years. It is therefore important to establish novel and effective treatment strategies for further improve survival. With successful treatment of unresectable esophageal squamous cell carcinoma (ESCC) with PD-1/PD-L1 inhibitors, which are expected to provide better benefits in resectable ESCC preoperatively. However, owing to lack effective predictors in MPR in neoadjuvant immunotherapy, efficacy of treatment is unsatisfactory. In this study we sought to explore potential biomarkers in treatment of locally advanced ESCC with tislelizumab combined with chemotherapy preoperatively. Methods: In this single centre, perspective, single arm study, 62 locally advanced (stage II-IVA) ESCC pts were enrolled from January 2023 to December. Pts received tislelizumab (200mg/ d1 Q3W) and chemotherapy (Albumin Paclitaxel 240 mg/m2, Carboplatin: AUC=5 Q3W, d1 or Nedaplatin: 70mg d1 Q3W). Minimally invasive esophagectomy was performed within 4-6 weeks after preoperative therapy. The primary endpoint was MPR rate and secondary endpoints were R0 resection rates and adverse events (AEs). Exploratory biomarker analysis was performed on tumor biopsy before neoadjuvant therapy. Results: 62 pts were enrolled who received all cycles of tislelizumab plus chemotherapy and 84% (52/62) of whom proceeded to surgery. Grade I AEs were observed in 57 (91.3%) pts and most common of which was anemia (49/62, 79%). 19 (30.6%) pts had grade II and 4 (6.4%) had grade III AEs. No higher AEs was observed. Reasons for not undergoing surgery was patient refusal (10/62, 16.1%). No perioperative death was observed. MPR, pCR and R0 resection rate were (55.8%), (23.1%) and (100%), respectively. The mediate follow-up time was 7.4 (1.7-12.6) months and no relapse was found before the last follow-up.10 pts underwent RNA-sequencing, of which 5 achieved MPR and 5 were not. Compared to MPR pts, 393 upregulated and 1950 downregulated genes were found in non-MPR patients. Additionally, it was indicated that immunomodulatory, keratinocyte differentiation and calcium signaling pathway may correlate with MPR status by GSEA, GO and KEGG analysis. Moreover, some hub genes, such as IL6, MMP1, SPPR3, CRNN, were identified to be associate with non-MPR after neoadjuvant therapy. Conclusions: Our results indicated that tislelizumab combined with chemotherapy is a feasibility and effective neoadjuvant treatment option for locally advanced ESCC. In addition, some hub genes were found to be associated with non-MPR after neoadjuvant therapy. Further experimental studies are needed to investigate these findings. Clinical trial information: NCT05880082 .

BIOLUMA: A phase II trial of nivolumab and ipilimumab in lung cancer—Results from the SCLC TMBhigh cohort.

8099 Background: Therapeutic options and prognosis for patients with small-cell lung cancer (SCLC) remain poor. Treatment with checkpoint inhibition can achieve remarkable responses, but this holds true for a small percentage of SCLC patients only. While tumor mutation burden (TMB) emerged as possible predictive biomarker for nivolumab and ipilimumab combination therapy in SCLC patients, to our knowledge, tissue-based TMB has never been evaluated prospectively in SCLC patients. Here, we present the results of the cohort 2b of the BIOLUMA trial, which evaluates efficacy and safety of nivolumab in combination with ipilimumab in SCLC patients with high tumor mutation burden. Methods: BIOLUMA is an investigator initiated multicentre non-randomised phase II trial in 2nd line patients with SCLC. The initial all-comer SCLC cohort was amended for inclusion of patients with high TMB only. FFPE tumor tissue was used for TMB pre-screening by whole exome sequencing (WES) at time of first diagnosis. TMBhigh was defined as the upper tertile of total missense mutations. After progression on platinum-based therapy, patients received 4 cycles of nivolumab 1 mg/kg q3w in combination with ipilimumab 3 mg/kg q3w and subsequently nivolumab 240 mg flat dose as monotherapy. Primary endpoint was overall response rate (ORR) of the combination therapy. Additionally, exploratory analyses of sequential tumor biopsies and blood samples were performed at different time points. Results: TMB analysis was feasible for most patients without necessity of performing additional tumor biopsy. Evaluation of TMB on FFPE tumor tissue obtained at first diagnosis was sufficient for TMB analysis in 92.5% of cases. TMB status was determined for 297 patients: 45.8% belonged to the TMB high group, while 54.2% had low or medium TMB. In total, 45 TMBhigh patients were enrolled in the study with 44 subjects evaluable for primary endpoint analysis. Six patients (13.6%) showed response to therapy, of whom in 4 patients (9%) response could be confirmed according to RECIST 1.1 criteria. One patient, who is not evaluable for endpoint analysis experienced a remarkably long lasting PR, which is still ongoing for more than three years. This patient received concomitant palliative radiation during induction with nivolumab and ipilimumab. Disease control rate (DCR) was 20.4% (n=9), three more patients showed unconfirmed SD. Three patients with confirmed PR or SD experienced long lasting treatment benefit, which is still ongoing at data cut-off. Conclusions: This represents the first trial to prospectively evaluate the combination therapy of nivolumab and ipilimumab in TMBhigh SCLC patients. The primary endpoint ORR was not reached. However, we observed an impressive clinical benefit in single patients, which warrants further investigation in order to get more insight into the mechanisms leading to these long-lasting tumor responses. Clinical trial information: NCT03083691 .

Investigation of a potential protein biomarker signature that may predict clinical benefit of NT-I7 and pembrolizumab in patients with cold gastrointestinal tumors.

2563 Background: Microsatellite stable colorectal (MSS-CRC) and pancreatic cancer (PDAC) are immunologically cold tumors due to low immunogenicity and lack of genomic diversity. NT-I7, a long-acting IL-7, and pembrolizumab (pembro) show efficacy in these hard-to-treat indications. While a limited set of patients (pts) achieve objective response, frequency and duration of the disease control rate point to a larger subset obtaining clinical benefit. To identify novel predictive biomarkers, we analyzed baseline peripheral and biopsy samples from pts based on treatment duration. Methods: Open-label Phase 2a study in pts with relapsed/refractory checkpoint inhibitor-naïve MSS-CRC and PDAC; NT-I7 1200 µg/kg IM every 6 weeks (Q6W), pembro 200 mg IV Q3W. Subjects were grouped by treatment duration, measured in NT-I7 doses administered before treatment discontinuation for any cause: 1 dose was short (ST), 2-3 doses medium (MT) and ≥4 doses long (LT). Correlative studies included peripheral (proteomics, T cell receptor sequencing [TCRseq], single cell RNA sequencing [scRNAseq]), and biopsy (genomics, transcriptomics, TCRseq). Results: As of 02OCT2023, 53 evaluable pts completed or discontinued treatment; 5 are still on follow up. ST group included 21 pts, MT 22 and LT 10 (including all 5 partial responders). Tumor biopsies were confirmed MSS with low tumor mutational burden (TMB). LT pts had similar age (59.0 [53.0-71.5] vs 66.0 [47.3-73.5]; ST vs LT) and lower baseline tumor burden (81.0 mm vs 58.0 mm; ST vs LT, p = 0.022). Biopsy analysis showed LT pts had, at baseline, upregulated pathways related to immune activity despite confirmed cold tumor status. Baseline scRNAseq in peripheral blood showed that stem-like CD8 T cells (precursors of exhausted [TPEX] and stem-cell memory [TSCM]) had a differential activation pattern in LT pts; those pathways were enriched in memory effector subsets in ST pts. Preserved antigen-specific stemness may be needed for NT-I7 + pembro efficacy. Baseline concentrations of 3 proteins that can be produced by growing tumors were significantly increased in ST pts. Pts were classified based on elevated levels of these potential biomarkers: POSITIVE (≥2 biomarkers; 20 pts) and NEGATIVE (≤1 biomarker; 33 pts). Pts with NEGATIVE signature at baseline had significantly higher overall survival, regardless of ST, MT or LT status (13.2 vs 8.9 months, p = 0.030). Conclusions: Preserved tumor-specific TPEX activity may be required for NT-I7 + pembro activity based on its presence in LT pts, who remained on treatment the longest. According to this analysis, there are 3 potentially predictive protein biomarkers that may help identify a pt subset more likely to experience clinical benefits from the combination treatment of NT-I7 + pembro. Further verification of the predictive nature of this signature in independent cohorts is ongoing. Clinical trial information: NCT04332653 .

Randomized phase II evaluation of nivolumab (nivo), or relatlimab (rela), or combined nivo-rela lead-in followed by nivo-rela as first line therapy for patients (pts) with advanced melanoma (mel).

9525 Background: A phase II study of nivo and rela was designed to evaluate the separate antitumor activity of nivo and rela vs. the combination for first-line treatment of pts with advanced mel. We report objective response rate (ORR) at week (wk) 4 and 16, progression-free survival (PFS) for pts receiving lead-in with nivo or rela vs. combination, and correlations with immune-related pathological response (irPR) at wk 4 tumor biopsy. Methods: Pts were randomized (1:1:1) to lead-in treatment with 1 cycle of nivo (480mg IV q4wk), rela (160mg IV q4wk), or nivo-rela followed by combination therapy in all pts. The primary endpoint was ORR to nivo-rela by RECISTv.1.1 at wk 16. Secondary endpoints included progression-free survival (PFS), ORR according to lead-in therapy at wk4, safety, and major pathological response on biopsy at 4wk (MPRbx) per Stein et al, Ann Oncol (2019). Results: The trial enrolled 43 advanced mel pts, median age=67 years, female=15 (35%), ECOG PS 0=34 (79%), BRAFmutant=18 (42%), Stage IV=35 (81%), and LDH >ULN=37 (86%). Pts were randomized to nivo=15, rela=14, and nivo-rela=14 lead-in arms. ORR at wk 4 were 3 (20%), 1 (7.1%), and 0 (0%) in nivo, rela, and nivo-rela lead-in arms, respectively. Among 41 evaluable pts who received at least one cycle of nivo-rela radiological assessment at wk16 was partial response (PR)=14 (34.2%), stable disease (SD)=15 (36.6%), and progressive disease (PD)=12 (29.3%). ORR at wk 16 were 6 (42.9%), 2 (15.4%), and 6 (42.9%) for nivo, rela, and nivo-rela lead-in arms, respectively. Median PFS for the whole cohort was 6.5 mos (95%CI 2.2-not reached [NR]), 4.7 mos, 1.8 mos, and NR in nivo, rela, and nivo-rela lead-in arms, respectively. After adjusting for BRAF status, rela lead-in was significantly associated with worse PFS (HR=3.41, 95% CI 1.11-10.4, p=0.03). Grade ≥3 treatment-related adverse events (TRAEs) were observed in 14 (32.6%) pts. & TRAEs (any grade) leading to treatment discontinuation were observed in 9 (20.9%). After 1 cycle of nivo one pt developed myocarditis leading to death without proceeding to nivo-rela. MPRbx at wk 4 was observed in 11 (31.4%) of 35 evaluable pts and were 50%, 0%, and 43% in nivo, rela, and nivo-rela lead-in arms, respectively. MPRbx was associated with wk16 radiological response (p=0.04) and improved PFS (HR=0.29, 95% CI 0.10-0.87, p=0.03). Nivo-rela resulted in increased CD8 and CD4+FOXP3- cell densities at wk4 (p<0.01 and p=0.03, respectively) and CD8 density at wk 4 was associated with improved PFS (p=0.02). Conclusions: Nivo-rela results in 34.2% ORR and median PFS of 6.5m in pts with advanced mel after lead-in nivo, rela or combination therapy. This first single agent lead-in rela evaluation demonstrated wk 4 ORR of 7%, wk 16 ORR of 15.4% and median PFS 1.8 mos. MPRBx and CD8 density at wk4 are associated with improved PFS. Clinical trial information: NCT03743766 .

Clinical efficacy of a next-generation sequencing (NGS) and immunohistochemistry (IHC) panel in patients with advanced cancer in Argentina.

e15154 Background: The analysis of somatic genomic alterations, evaluation of DNA mismatch repair (MMR) proteins, and examination of PD-L1 expression in tumor biopsies are crucial for prognosis and informed therapeutic decisions. However, their clinical implementation in Argentina faces challenges due to economic costs and lack of evidence. To address this, we conducted a retrospective study to assess the impact of this molecular panel testing on treatment decisions and clinical management of cancer patients in Argentina. Additionally, we evaluated its ability to detect clinically relevant alterations and analyzed the frequency and co-occurrence of mutations in our cohort. Methods: Tumor tissue samples from 266 patients with primary tumors, representing 26 different anatomical sites (53% lung cancer), underwent molecular testing using the Optimus panel developed by Biomakers. The assay integrates somatic sequencing of 52 genes through NGS with IHC assessment of MMR and PD-L1 proteins. A retrospective evaluation of the clinical effectiveness of the test was conducted on 133 patients. Genomic and clinical data were analyzed using R with the pairwise Fisher’s exact test applied for statistical analysis. Results: This panel facilitates molecular characterization, identifying clinically relevant genetic alterations in 65% of patients and detecting deficiency in MMR proteins in 3%. Findings align with global clinical trial availability for identified alterations in 97% of cases. KRAS is the most frequently mutated gene (38%), followed by EGFR (19%), PIK3CA (12%), BRAF (9%), CDK4, and CTNNB1 (5% each), correlating with lung cancer overrepresentation. Simultaneous alterations in EGFR, PIK3CA, CTNNB1, and KIT genes were observed. Pan-tumoral interaction analysis revealed mutual exclusivity between KRAS mutations and those in EGFR, BRAF, CDK4, and CTNNB1. CTNNB1 mutations co-occurred with EGFR mutations, akin to KIT and PDGFRA (p<0.05). The retrospective analysis indicated that the Optimus panel contributed to clinical management of patients in 56% of cases, with 85% detecting clinically relevant variants, aiding treatment definition in 74% of these cases. Conclusions: The Biomakers-developed Optimus panel empowers the molecular characterization of genomic and proteomic biomarkers across tumor types. Its significance in clinical practice lies in contribution to vital decision-making processes, particularly in treatment selection.