High Tumor Research Articles

Immune checkpoint inhibition for the treatment of metastatic breast cancer with high tumor mutational burden: Real world clinical and genomic correlates of response.

1078 Background: Pembrolizumab has received tumor-agnostic approval for the treatment of unresectable/metastatic solid tumors carrying a tumor mutational burden (TMB) >10 mut/Mb. The registrational KEYNOTE-158 study, however, did not include any patients with metastatic breast cancer (MBC). Here we present a retrospective study of patients with TMB-high MBC treated with immune checkpoint inhibition (ICI) and report real-world efficacy endpoints, including progression free survival as well as clinical and genomic characteristics that may be associated with duration of response. Methods: All patients with MBC treated with an ICI at MSK and with TMB-high tumors (>10 mut/Mb) assessed by tumor-normal targeted sequencing (MSK-IMPACT) were included. Clinicopathological and demographic data were obtained via the MSK Breast Cancer Translational Program. Mutational signatures were determined using the Signature Multivariate Analysis (SigMA) algorithm. Real world progression free survival (PFS) was determined clinically and analyzed using Kaplan-Meier estimates. Univariate and multivariate analyses were performed using Cox-proportional hazards models. Results: Of 688 patients with TMB-high breast cancer at MSKCC, 87 had received ICI-based therapy for estrogen receptor positive (ER+), triple negative breast cancer (TNBC), and HER2+ MBC. Of those, 45 patients were treated with ICI monotherapy (29 ER+, 11 TNBC, 5 HER2), 31 were treated with ICI + chemotherapy (12 ER+, 19 TNBC), and 11 were treated with combinations of ICI and targeted therapy (8 ER+, 1 TNBC, 2 HER2). Median age at time of ICI treatment across all patients was 60. ICI was the median 5th line therapy for all patients (range 1-16). Median PFS of ICI for all patients was 3.17 months (95%CI 2.27-5.5). Multivariable analysis did not show statistically significant differences in PFS based upon treatment regimen (monotherapy vs. chemoIO HR 1.03, 95%CI 0.54-1.96, p= 0.92, monotherapy vs combination IO HR 1.66, 95%CI 0.69-4.02, p=0.26), ER status (ER- vs ER+, HR 1.20, 95%CI 0.63-2.28, p=0.57), or HER2 status (HER2- vs HER2+, HR 1.63, 95%CI 0.51-5.20, p=0.41. However, longer PFS was significantly associated with TMB>30 (HR 0.35, 95%CI 0.13-0.92, p=0.03) and dominant APOBEC signature score (APOBEC- vs APOBEC+, HR 0.49, 95%CI 0.25-0.98, p=0.04). Shorter PFS was significantly associated with later treatment line at the time of ICI exposure (continuous, HR 1.22, 95%CI 1.11-1.36, p=0.0001). Conclusions: In this heavily pretreated real-world cohort, ICI in TMB high MBC shows modest clinical activity. Our analysis suggests that ICI may be more effective in MBC patients that are less heavily pre-treated, have TMB>30, and have a predominantly APOBEC mutational signature. Further translational work is necessary to explore the mechanisms of these findings.

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]

Results of a phase 2 study of evorpacept (E, ALX148), cetuximab (C), and pembrolizumab (P) in patients with refractory microsatellite stable metastatic colorectal cancer (MSS CRC).

3530 Background: Single-agent anti-PD-1/PD-L1 drugs are ineffective in MSS CRC. E is an engineered protein (high-affinity CD47-blocker fused to an inactive IgG Fc region), which blocks the CD47/SIRPα innate immune inhibitory phagocytosis checkpoint expressed on CRC and phagocytes, respectively. Preclinical evidence suggests ECP may be effective in MSS CRC. Methods: This phase 2, single-arm, two-stage, multicenter, investigator-initiated trial of E (15 or 10 mg/kg weekly at dose level [DL] 1 and -1, respectively), C (400 mg/m2 then 250 mg/m2 weekly), and P (200 mg every 3 weeks) in 21-day cycles enrolled patients with MSS CRC, regardless of tumor sidedness and RAS/BRAF status, refractory to ≥ 2 prior lines of therapy, including EGFR inhibitor if indicated (NCT05167409). All patients in both Stage 1 (safety run-in) and Stage 2 (expansion) received ECP until progression or unacceptable toxicity. The co-primary objectives were to determine the recommended dose (RD) of E with CP and objective response rate (ORR) by RECIST v1.1 (by one-sided exact test with α=0.05, H0 p ≤ 3% [historical controls], HA p ≥ 15%; power is 87% with N=48). Results: The safety-evaluable population included 16 patients, of whom 69% were male and median age 53 years. The primary tumor was in the right, left, and transverse colorectum in 31%, 31%, and 6% of patients, and was unknown in 31%. Mutations in KRAS, NRAS, and BRAF genes were present in 38%, 6%, and 0% of patients. The median number of prior lines of therapy was 3, including prior EGFR inhibitor in 44%. In Stage 1, 9 and 3 patients were enrolled at E DL1 and DL-1, respectively. E DL1 was established as the RD for Stage 2, in which 4 patients were enrolled. The most common any-grade treatment-emergent adverse events were headache (32%), fatigue (26%), anemia (21%), diarrhea (21%), dyspnea (16%), abdominal pain (16%), nausea/vomiting (16% each), and acneiform rash (16%). There were two on-study deaths assessed as related to all three study drugs (hemophagocytic lymphohistiocytosis and cytokine release syndrome; 1 each). While both are known associations with checkpoint inhibitors, other significant factors contributing to these event outcomes included cancer progression with high tumor burden in the former and patient decision to transition to comfort care in the latter. In the safety-evaluable population, ORR was 6.3% (1 ongoing partial response, 95% confidence interval [CI] 0.2-30.2%), disease control rate was 12.5% (95% CI 1.6-38.4%), median progression-free survival was 2.6 months (mo; 95% CI 2.1-2.9 mo), and median overall survival was 10.9 mo (95% CI 3.3 mo-infinity). Formal hypothesis testing was not performed. Conclusions: Further dose optimization of ECP is needed to establish a RD in the refractory MSS CRC population. While initial activity was seen, at the DLs evaluated, criteria for study termination were met. Clinical trial information: NCT05167409 .

Trophoblast cell-surface antigen 2 is a biomarker and potential therapeutic target in human colon cancer.

e15514 Background: Trophoblast cell-surface antigen 2 (TROP2), a transmembrane glycoprotein in epithelial cells, is implicated in malignant progression, notably in breast cancer therapy. However, the clinicopathologic aspects of TROP2 in colorectal cancer (CRC) are unclear. This study aims to explore the association between TROP2 expression and clinicopathological features in CRC and investigate the inhibitory effects of the anti-TROP2 antibody-SN-38 conjugate (ADC-TROP2) on colon cancer cells. Methods: A retrospective analysis of 1296 CRC patients who underwent colorectomy at Renji Hospital, Shanghai Jiaotong University School of Medicine, was conducted. Immunohistochemistry determined the expressions of TROP2, HER2, and PD-L1 in colon cancer tissues. Statistical analyses, including the chi-square test and Cox proportional hazards model, assessed associations. Sacituzumab Govitecan (ADC-TROP2 drug) cytotoxicity on human cancer cells was determined using the MTT method. Results: TROP2 was predominantly expressed at the cell membrane of cancer tissues, with 50% of cases TROP2-positive. The overexpression of TROP2 (staining extension 2+ or 3+) were found in 356 (27.5%) cases. The clinicopathological features of all 1296 patients based on the TROP2 expression in their cancer cells were summarized in Table 1. Compared to TROP2 negativity expression, the high TROP2 expression was significantly associated with the advantaged tumor stage (III/IV, P = 0.022), high tumor invasion depth (T3/T4, P = 0.002), lymph node metastasis (N1/N2, p = 0.026), HER-2 expression (2+/3+, p = 0.013) ,PD-L1 CPS (CPS≤5,P = 0.007). Sacituzumab Govitecan exhibited stronger inhibition in TROP2-positive human CRC cells in TROP2-negative CRC cells compared to TROP2-negative cells and the control SN-38 agent. Conclusions: TROP2 expression positive in 50% of CRC cases is associated with with advantaged tumor stage, high tumor invasion depth, lymph node metastasis. Sacituzumab Govitecan demonstrates potent targeting of TROP2-positive CRC cells, suggesting TROP2 as a potential biomarker for clinical prognosis and therapeutic targeting in colon cancer. [Table: see text]

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 .

Outstanding safety and efficacy data of IMC002, an autologous CLDN18.2-targeting CAR-T, in CLDN18.2+ advanced solid tumors.

e16012 Background: Claudin 18.2 (CLDN18.2) is a promising therapeutic target for advanced solid tumors with CLDN18.2 expression. IMC002 is an autologous CLDN18.2-targeting CAR-T cell directed by a CLDN18.2-specific VHH, the specificity of which was confirmed by a membrane proteome array assay. Preclinical studies showed that IMC002 exhibited high tumor specificity, anti-tumor efficacy, and excellent safety profile in both cell and animal models. Methods: This is an open label first in human Phase 1 dose escalation study to evaluate the safety and efficacy of IMC002 in advanced solid tumors with CLDN18.2 expression which is defined as CLDN18.2 expression of ≥1+ membrane staining intensity in ≥10% tumor cells. Accelerated titration followed by Bayesian optimal interval design was adopted with a total of 4 dose levels planned at 1, 3, 5 and 7 million (mil) CAR-T cells/kg respectively. All patients (pts) were given a single dose of IMC002 infusion after lymphodepletion chemotherapy. Dose limiting toxicity (DLT) was evaluated during the 28-day period after IMC002 infusion. Safety, anti-tumor activity, pharmacokinetics and pharmacodynamics were explored in this study. Here, we present preliminary safety and efficacy data for the pts dosed with up to 3 mil CAR-T cells/kg. Results: As of January 17, 2024, 3 advanced unresectable gastric cancer pts received IMC002 infusion, 1 patient at 1 mil CAR-T cells/kg and 2 pts at 3 mil CAR-T cells/kg. No DLT or SAE was reported. Manageable CRS (grade 1) was reported in all 3 pts. Other adverse events related to cell therapy included grade 1-2 lipase increase (3/3), diarrhea (1/3), pruritis (1/3) and γ-GGT increase (1/3). All adverse events recovered quickly. Preliminary efficacy data showed that best overall response of the 3 pts was all stable disease as evaluated by RECIST 1.1. The two pts at the dose level of 3 mil CAR-T cells/kg underwent successful radical surgery at week (W) 11 and 44 after IMC002 infusion respectively. Pathological complete response (pCR) was achieved in the patient with surgery at W44. Distinct CAR-T cell expansion in peripheral blood was observed in all 3 pts, with the peak number of CAR+ cells reaching on day 7-11 in the peripheral blood after the infusion. Moreover, CAR-T cell infiltration was detected in the W11 and W44 surgical samples. Significant elevations of serum levels of IFN-γ, IL-10, IP-10, IL-2 and IL-6 were observed in the 3 pts. The trial is ongoing. Conclusions: IMC002 showed a favorable safety profile, encouraging anti-tumor activities with observed pCR and persistent expansion in the tumor tissue at the low dosage levels in pts with advanced CLDN18.2+ gastric cancer. In addition, our trial has successfully provided a surgical treatment opportunity after CAR-T therapy downstaging of unresectable gastric cancers. Clinical trial information: NCT05472857 .

Nivolumab plus ipilimumab (N+I) in patients (pts) with solid tumors with high tumor mutational burden (HTMB): Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) Study.

3130 Background: TAPUR is a phase II basket study evaluating antitumor activity of commercially available targeted agents in pts with advanced cancers with genomic alterations. Results in a cohort of pts with advanced solid tumors with HTMB treated with N+I are reported. Methods: Eligible pts had measurable disease, ECOG performance status (PS) 0-2, adequate organ function, and no standard treatment (tx) options or prior immune checkpoint inhibitor tx. PD-L1 expression testing was not required. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. HTMB was defined a priorias ≥9 mutations/megabase (Muts/Mb) via a qualifying test for TAPUR or approved by the Molecular Tumor Board. Pts received I at 3 mg/kg every 3 weeks (wks) for 4 doses with N at 1 mg/kg IV every 3 wks for 4 doses. N alone was then continued at 240 mg every 2 wks or 480 mg every 4 wks until disease progression. Low accruing histology-specific cohorts with HTMB were collapsed into 1 cohort for analysis. Primary endpoint was disease control (DC) per investigator defined as complete (CR) or partial (PR) response per RECIST v. 1.1, or stable disease (SD) of at least 16 wks duration (SD16+). The hypothesized null DC rate of 15% was evaluated by a 1-sided exact binomial test (α= 0.10; 86% power based on alternative DC rate of 35%). Secondary endpoints were progression-free survival (PFS), overall survival (OS), objective response (OR), duration of response (DOR), duration of SD, and safety. DOR is time from documented OR to progressive disease (PD); duration of SD is time from tx start to PD. Results: 26 pts with 13 tumor types with HTMB were enrolled. Table shows demographics and outcomes. Tissue tumor mutational burden (TMB) ranged from 8 to 374 Muts/Mb (median= 16). 1 CR (small intestine; TMB= 48 Muts/Mb; DOR= 36 wks), 7 PR (biliary tract, site unspecified [3], soft tissue sarcoma, uterus, vagina; median TMB= 17 Muts/Mb; median DOR= 20 wks [range, 5-231]) and 1 SD16+ (pancreas; TMB= 26 Muts/Mb; duration of SD= 26 wks) were observed for a DC rate of 35% (1-sided 90% CI: 22 to 100) and OR rate of 31% (95% CI: 14 to 52). The null hypothesis was rejected (p=0.011). Notably, 1 pt (uterus, 374 Muts/Mb) is still on tx with an ongoing 66-wk PR as of Jan 2024. Most pts, including 8/9 with DC, were microsatellite stable. 10 pts had ≥1 grade 3 tx-related adverse event (AE) or serious AE. Conclusions: N+I showed antitumor activity in pts with advanced solid tumors with HTMB. Additional study is warranted to confirm the efficacy of N+I in pts with HTMB. Clinical trial information: NCT02693535 . [Table: see text]

Efficacy of cytotoxic chemotherapy in recurrent/metastatic adenoid cystic carcinoma (ACC).

6111 Background: Despite aggressive local therapy, many ACC patients (~50%) develop recurrent and/or metastatic (R/M) disease. However, there is no standard of care or FDA-approved systemic therapy for this population. Based on small phase II trials, mostly including multiple salivary gland histologies, cytotoxic chemotherapy is recommended for symptomatic patients with high tumor burden, but its efficacy and impact on survival in R/M ACC remain unsubstantiated. Methods: A retrospective cohort study was conducted at MD Anderson Cancer Center with an institutional ACC database (N=769). Patients diagnosed with R/M ACC and treated with single-agent or combination palliative-intent chemotherapy were included. The primary endpoints were overall response rate (ORR) and disease control rate (DCR) per RECIST 1.1. Secondary endpoints were median overall survival (mOS) and progression-free survival (mPFS) on chemotherapy for the entire cohort and stratified by growth pattern (solid v non-solid), line of therapy (1 v >2), chemotherapy regimen, and stage at diagnosis (M0 v M1). Results: 48 out of 115 patients who received chemotherapy were evaluated for response per RECIST.Median age at diagnosis was 43.6 years. 56% were male, 79% had M0 stage at diagnosis, 67% had minor salivary gland primary tumors, 52% had solid growth pattern, 31% had non-solid growth pattern, and 54% received first-line chemotherapy. The most common regimens were Platinum/Vinorelbine (38%), Platinum/Taxane (27%) and CAP (15%).The ORR and DCR rates were 12.5% and 56.3% respectively; 6 had partial response, 21 had stable disease, and 21 had progressive disease. The ORR and DCR rates were 20% and 52% for solid and 6.7% and 73.3% for non-solid growth pattern, respectively. The mOS from diagnosis was 7 years (95% CI, 3.5-10.7). The mOS on chemotherapy was 16 months (95% CI, 10.8-24.5). There was a significant difference in mOS between solid and non-solid growth pattern (10.8 v 24.1 months, p=0.015), but not by line of therapy, regimen, or stage at diagnosis. The mPFS on chemotherapy was 4.3 months (95% CI, 2.8-6.3 months). There was a significant difference in mPFS between solid and non-solid growth pattern (4.0 v 7.3 months, p=0.018), but not by line of therapy, regimen, or stage at diagnosis. Conclusions: In this largest to date real-world data on chemotherapy in ACC, response and survival outcomes were lower than historical data. The efficacy of chemotherapy may vary by growth pattern and other patient and tumor factors, which requires further investigation. Given the low ORR and overall slow-growing disease pattern, tumor volumetrics may be better than RECIST to assess treatment benefit.

Impact of intratumor heterogeneity (ITH) on survival outcomes in patients with non-small cell lung cancer (NSCLC) with high tumor mutational burden (TMB-H).

e20519 Background: Heterogeneity among cancer cells within a tumor significantly impacts cancer development and resistance to treatment. Currently, no standard measure exists for assessing ITH in routine clinical settings. In this study, we applied a quantitative metric to assess intratumor genetic diversity in NSCLC, using a large, multicenter database. Methods: We accessed the Tempus database for next-generation sequencing results from patients with NSCLC who underwent immune checkpoint inhibitor (ICIs) monotherapy as their first-line treatment. We calculated the mutant-allele tumor heterogeneity (MATH), defined as the ratio of the distribution's range to the median of mutant-allele fractions across tumor-specific mutated loci. The primary outcomes were progression-free survival (PFS) and overall survival (OS). Results: A total of 160 pembrolizumab Significant differences in PFS between high and low MATH groups (MATH-H and MATH-L, respectively), using the 50th percentile as the cutoff, were observed among patients with stage 4 adenocarcinoma who had TMB-H above the 25th percentile (Table). In this subgroup, with 27 patients in the MATH-H/TMB-H group and 22 in the MATH-L/TMB-H group, the MATH-H/TMB-H group showed improved PFS (median PFS 5.19 vs. 1.61 months; p = 0.02). Differences in PFS were also observed among patients with TP53, KEAP1, and MET mutations (p < 0.001, p = 0.02, and p = 0.004, respectively). TP53 mutations were found in 27.6% of the MATH-H group and 27.8% of the MATH-L group, KEAP1 mutations in 8.2% and 10.1%, respectively, and MET mutations in 5.1% and 8.9%, respectively. No significant PFS differences were found in groups with low TMB, other stages, or squamous histology. Conclusions: Our findings suggest that higher genetic diversity within stage 4 TMB-H lung adenocarcinoma, as quantified by MATH, might be linked to improved clinical outcomes among those who receive pembrolizumab as first-line therapy and supports further exploration of MATH as a predictive/prognostic biomarker. [Table: see text]

A machine learning algorithm based on multi-omics biomarkers for the detection of tumor microsatellite instability.

1554 Background: Microsatellite instability (MSI) occurs via defects in mismatch repair (MMR) and is characterized by high tumor mutational burden (TMB) and a robust inflammatory response. Accurate MSI-high classification of immune-evasive tumors is vital due to the effectiveness of immune checkpoint inhibitor (ICI) therapy, such as pembrolizumab, which is FDA approved for all MSI-high tumors irrespective of anatomic origin. Detection methods of MSI-status vary widely, including immunohistochemistry (IHC), polymerase chain reaction (PCR), and next-generation sequencing (NGS). We developed a machine learning (ML) model to predict MSI status in patients with solid tumors using comprehensive genomic and immune profiling (CGIP), independent of direct sequencing data from microsatellite sites. Methods: We analyzed samples from 1,838 patients with colorectal cancer (CRC) by CGIP, which included DNA panel testing (523 genes) for pathogenic single nucleotide variants (pSNV) and determination of TMB (mut/Mb), and RNA sequencing (397 genes) for gene expression (GEX). The Boruta algorithm was used to select key genomic and GEX changes associated with MSI status. A distributed gradient boosting algorithm created a predictive model that was trained on 70% of the cohort. The model was tested on the remaining CRC cohort (Test), and in the PanCancer Atlas CRCs (TCGA), endometrial adenocarcinomas (EMCA), and CRC with indeterminate MSI testing by CGIP. Performance of the trained model was assessed using sensitivity, specificity, and positive (PPV) and negative (NPV) predictive value. Results: Feature selection identified 79 genes with pSNVs, 63 GEX changes, and TMB as informative for MSI prediction. The model showed high predictive accuracy in differentiating MSI-H tumors. Of the 39 cases that failed MSI component of CGIP (Indeterminate), 17 had MMR IHC results available, of which 1 demonstrated loss of MLH1/PMS2 and the other 16 showed intact (normal) expression. Testing of this cohort identified 3 cases as MSI-high, at least one of which was confirmed by IHC. No cases with intact MMR protein IHC were identified as MSI-high by the algorithm. Conclusions: Our ML-driven approach accurately assessed MSI status of CRC and EMCA using CGIP data. This approach also identified potential cases with MSI-high status where direct sequencing of microsatellites failed. This study highlights a method to identify patients with potential MSI-high status for orthogonal screening with the MSI component of a test fails. [Table: see text]

Immunotherapy for local/regional control of locally advanced orbital and periocular squamous cell carcinoma.

e18034 Background: Periocular squamous cell carcinoma can be of eyelid skin, ocular surface (bulbar) or palpebral conjunctival, or of lacrimal sac/nasolacrimal duct mucosal origin, is relatively rare, and presents unique anatomic considerations due to proximity to the eye and inherent risk to ocular structures associated with high dose radiation therapy. We herein report on 17 patients with orbital or periocular SCC who were treated with immunotherapy (IO) to decrease surgical morbidity or to avoid high dose radiation therapy. Methods: Retrospective review of all previously unreported patients with orbital, conjunctival, or periocular SCC who were treated with IO either in the neoadjuvant setting prior to surgery or for treatment of periocular SCC with perineural spread into the orbit and skull base. Results: 17 patients, 12 men and 5 women (Age range: 44-92; median=70 years old) with orbital (n=6), conjunctival (n=5), or lacrimal sac/duct (n=2) squamous cell carcinoma (SCC), or periocular SCC with perineural spread into the orbit and skull base (n=4) who were treated with IO either as single drug (n= 11) or in combination with chemotherapy (n= 6 ). In all patients either cemiplimab or pembolizumab was used. In 13 patients IO was used in the neoadjuvant setting prior to planned surgery. In 4 patients with perineural spread as they had non surgically resectable disease, IO was used to avoid high dose radiation therapy with its inherent significant risk of ocular toxicity. Overall, 3 patients achieved complete response, 10 patients achieved partial response, and 4 patients had stable disease, using RECIST criteria. One of 5 patients with conjunctival SCC also had nodal metastasis at presentation and achieved a dramatic complete response of both the conjunctival tumor and the nodal metastasis and managed to avoid surgery altogether. This patient had a very high tumor mutation burden (TMB). One patient developed diabetic ketoacidosis as a side effect of IO; otherwise the adverse effects were low grade. Conclusions: IO either as single drug or in combination with chemotherapy has a fairly high response rate in patients with ocular adnexal, conjunctival or orbital SCC and in patients with periocular SCC with perineural spread in the orbit and skull base. Future prospective trails using IO for orbital and ocular adnexal SCC should be planned and should aim to correlate molecular data such as TMB with response.

Clinical outcomes and post-progression retreatment in patients with metastatic NSCLC who complete two years of treatment with immune checkpoint blockade.

8633 Background: Immune checkpoint inhibition (ICI) has significantly improved survival in patients (pts) with metastatic non-small cell lung cancer (NSCLC). While ICI duration is commonly limited to two years, the optimal duration of ICI and post-progression treatment outcomes in pts who received at least two years of ICI are unknown. Methods: We conducted an international, multi-center study of pts with metastatic NSCLC treated with ICI for at least two years to characterize clinical outcomes and post-progression treatment patterns. Log-rank tests were used to test for differences in event-time distributions, and Cox proportional hazards models were used to estimate HRs. Results: We identified 255 pts with metastatic NSCLC treated with ICI alone (N=210, 82.3%) or ICI + chemotherapy (N=45, 17.7%) for least two years. Median age was 63.0, 42.4% were women, 93.0% had history of tobacco use, 79.2% had adenocarcinoma histology, 61.4% had a PD-L1 TPS ≥50%. From the start of ICI, the median time to progression (mTTP) was 6.9 years (95%CI 4.9-NR) and the median overall survival (mOS) was 9.5 years (95%CI 8.0-NR). Pts wo achieved a complete/partial response to ICI had a significantly longer mTTP (HR 0.41, P<0.01) and mOS (HR 0.30, P<0.01) compared to those with a best objective response of stable disease. Patients with high PD-L1 ≥50% (HR 0.6, P=0.02 vs PD-L1 <50%), very high tumor mutational burden (TMB) ≥20 mut/Mb (HR 0.7, P=0.03, vs <20 mut/Mb) and ever smoking status (HR 0.52, P=0.04, vs never smokers) had also significantly longer mTTP. There was no difference in mTTP (HR: 0.98, P=0.94) and mOS (HR: 0.61, P=0.06) between pts who stopped ICI at two years of treatment (N=112) and those who continued ICI beyond two years (N=143). Among 96 pts who progressed after ICI, 33.3% (N=32) received local ablative therapies (surgery or radiation), 9.3% (N=9) pts received systemic chemotherapy and 31.2% (N=30) pts received ICI retreatment. Among those retreated with ICI, the response rate was 63%, mTTP and mOS from the date of start of ICI retreatment were 22.7 (95%CI 11.2-NR), and 41.7 months (19.3-NR), respectively. Clinico-genomic predictors of response to ICI retreatment included higher TMB at baseline (15 vs 7.6 mut/Mb, P<0.001), adenocarcinoma histology (94.4% vs 50.0%, P=0.01), and longer ICI treatment duration prior to retreatment (31.2 vs 24.5 months, P=0.02). Conclusions: Pts who received a minimum of two years of treatment with ICI experienced unprecedented long-term survival. There was no difference in outcomes between pts who stopped at two years compared to those who continue therapy. After completing two years of initial ICI therapy, a large fraction of pts who subsequently experience disease progression and are retreated with ICI experience an objective response, particularly those with longer duration of prior ICI treatment, higher TMB, and adenocarcinoma histology.

Therapeutic implications of acquired high tumor mutational burden (TMB-H) after targeted therapy (TT) in metastatic colorectal cancer (mCRC).

3542 Background: mCRC treated w/ TT can acquire a high number of mutations at progression. TMB is used as a proxy of neoantigen load for predicting benefit from immune checkpoint blockade (ICB). In TMB-H CRC, benefit to ICB is restricted to microsatellite unstable (MSI-H) hypermutated or POL-D/E ultramutated tumors. We asked whether TT can sensitize microsatellite stable (MSS) CRCs to ICB by inducing an acquired TMB-H state. Methods: We screened the MSK-IMPACT dataset for mCRC patients (pts) who received TT and underwent pre-treatment (pre-TT) and post-progression (post-TT) tissue or liquid biopsies (LBx). We included pts who received TT against EGFR, BRAF V600E, KRAS G12C, or HER2. DNA sequencing of tissue and LBx was performed w/ MSK-IMPACT and Guardant 360. MSI status was assessed with algorithms measuring somatic changes in length of repetitive sequences (e.g., MSIsensor). Due to known discrepancies between tissue TMB (tTMB) and blood TMB (bTMB), we defined acquired TMB-H as: 1) tTMB <10 mut/Mb or bTMB <20 mut/Mb pre-TT; 2) ≥5-fold increase in TMB post-TT; 3) tTMB ≥10 mut/Mb or bTMB ≥40 mut/Mb post-TT. Results: We identified 26 pts w/ paired samples that had been sequenced w/ determination of TMB. 4/26 (15%) met criteria for acquired TMB-H. None had detectable pathogenic mismatch repair or DNA damage repair alterations pre-TT. All 4 post-TT samples were LBx only. One pt’s tumor acquired a somatic MLH1 mutation and converted from MSS to MSI-H. In all cases, the majority of acquired mutations were subclonal w/ many at variant allele frequencies (VAF) of ≤1% (Table). After detection of acquired TMB-H, 2/4 pts received ICB. Pt 1 had RAS wild type mCRC w/ pre-TT tTMB 6.9. She received irinotecan + panitumumab for 25.8 months. Post-TT bTMB was 40.19 and met criteria for MSI-H. She received pembrolizumab and experienced clinical + radiographic progression of disease (POD) within 49 days. Pt 2 had KRASG12C-mutant mCRC w/ pre-TT bTMB 13.4 and tTMB 4.9. She received sotorasib + panitumumab for 3.2 months w/ post-TT bTMB 145.34. She received pembrolizumab + regorafenib and experienced clinical + radiographic POD within 37 days. Conclusions: In CRC, acquisition of TMB-H at progression w/ predominantly low VAF mutations suggests activation of enhanced mutagenesis due to therapeutic pressure from exposure to TT. In this context, TMB may not be an accurate reflection of tumor immunogenicity as it does not distinguish between clonal and subclonal alterations. Our data suggest that pts w/ acquired TMB-H following TT are unlikely to benefit from ICB. [Table: see text]

Plasma circulating tumor DNA in patients with cutaneous squamous cell carcinoma: Initial experience.

e15034 Background: Circulating tumor DNA (ctDNA) has emerged as a potential noninvasive biomarker to assess tumor burden throughout cancer treatment and to aid in clinical decision-making. However, data on the use of ctDNA in cutaneous squamous cell carcinoma (cSCC) is currently lacking. In this study, we report our first experience with ctDNA in patients with cSCC. Methods: In this IRB-approved study at a tertiary care center, an initial cohort of patients with intermediate to high-risk cSCC had tissue and plasma sent for ctDNA analysis using Natera®’s proprietary bioinformatics pipeline. This cohort included 21 patients treated from 2023 to the present. Initial tissue samples were obtained through biopsy (i.e., excisional, punch, or shave), Mohs surgery, or surgical resection. Some patients had additional plasma sample(s) drawn later during or after the treatment course. Patients either received a “positive,” “positive below analytical range,” or “negative” result or had ‘insufficient sample’ to receive a result based on Natera®’s analysis. All patients were treated curatively with surgical resection with or without adjuvant radiation as per the standard of care. The assessment of gross disease was determined based on whether the patient had disease present on imaging or physical exam at the time of the plasma draw. A comparison of ctDNA results and the presence of gross disease was done using Fisher’s exact test. Results: Of the samples submitted for Natera® ctDNA analysis, 18/21 had sufficient tissue for analysis of tumor DNA. All 3 tumors with insufficient tissue were from biopsies (6/9 sufficient), while 12/12 of those from Mohs or surgical resection had sufficient tissue. The average tumor volume in these patients with insufficient samples for tumor analysis was relatively low (0.35 cm3) compared to those that resulted (17-30 cm3). 7/9 (78%) patients with gross disease had a positive ctDNA result, which was significantly greater than those with no gross disease (1/9 patients, 11%) (p = 0.004). Three patients in our cohort with an initially positive ctDNA result had multiple plasma draws, with all having a later draw demonstrating a negative ctDNA result after having surgery and/or radiation. Conclusions: Circulating tumor DNA is a reliable marker for patients with cSCC with a high tumor burden and is feasible in those with adequate tissue. However, in patients where it is only possible to obtain a small volume of tumor tissue and/or low tumor burden, ctDNA may be a less reliable biomarker. [Table: see text]

Young adults (YA) with non-small cell lung cancer (NSCLC): Snapshot of the oncogenic drivers and immune landscapes.

8538 Background: Approximately 5% of NSCLC occurs in patients 50 years or younger (median age:71) representing distinct clinicopathological features. Reports characterizing genomic alterations are scarce. Using a large real-world (RW) dataset, we characterize oncogenic drivers, and immune landscapes to better understand YA with NSCLC. Methods: 42,326 NSCLC specimens were analyzed using next-generation sequencing of DNA (DNA-592 panel or whole exome) or RNA (whole transcriptome) at Caris Life Sciences (Phoenix, AZ). YA (<=50 years) were categorized into three groups (years): 18-30 (A1, n=61), 31-40 (A2, n=277) & 41-50 (A3, n=1,549); vs >50 (A4, n=40,439). Composition of tumor microenvironment (TME) was estimated from bulk RNA sequencing using QuanTIseq method. RW survival on Osimertinib (Osi-OS) was obtained from insurance claims and calculated from initiation of Osi treatment to last contact and was compared between ages 18-50 and >50 years. Hazard ratio (HR) was calculated using the Cox proportional hazards model. Statistical significance was determined using Chi-square, Fisher’s Exact, Mann-Whitney U and log-rank tests and corrected for multiple comparisons where applicable (q<0.05). Results: Consistent with previous reports, NSCLC in YA was more prevalent in females, non-smokers and was associated with adenocarcinoma histology. Among driver alterations, ALK(IHC+), ROS1, RET and NTRK1 fusion were enriched and KRAS mutations were reduced in YA. Interestingly, while the prevalence of KRASG12D from transition (non-smoker related) and EGFRE746_A750 decreased with age, KRASG12C from transversion increased with age in YA. YA were also associated with improved Osi-OS (HR: 0.79, median Osi-OS=37.4 months vs 32 months in >50 years old, p=0.019). High tumor mutation burden (>=10 mut/Mb), the prevalence of mutations in TP53, KMT2D, NF1, RBM10, NFE2L2 and NOTCH1 increased while GNAS decreased with age. The expression of immune checkpoint genes such as PDCD1LG2(A1/A4: 0.63, A3/A4: 0.89), LAG3(A2/A4: 0.73, A3/A4: 0.89) and IFNG (A1/A4: 0.32, A3/A4: 0.75) were reduced, while M2 macrophage (A2/A4: 1.2) and neutrophil (A2/A4: 1.2) were increased in YA (all q<0.05). Conclusions: We report an increased prevalence of RET and NTRK1 fusions in YA and key differences in distributions of frequent KRAS and EGFR mutations in YA (vs A4) along with decreased expression of immune related genes in the tumor microenvironment. The implications are under active investigation. [Table: see text]

Comprehensive analysis of TMB, TNB, and HLA via NGS sequencing in a large cohort of Chinese pan-cancer patients.

2656 Background: Evidence suggests that patients with high tumor mutational burden (TMB) and tumor neoantigen burden (TNB) are more likely to benefit from Immune checkpoint inhibitors (ICIs). Furthermore, loss of heterozygosity (LOH) in human leukocyte antigen (HLA) alleles, particularly HLA class I, impairs neoantigen presentation and contributes to resistance against ICIs. This study provides real-world insights into the distribution of TMB, TNB, and HLA variations within a large cohort of Chinese patients with various cancers. Methods: From 2021 to 2023, we performed a retrospective analysis on 1603 cancer patients, examining genetic mutations and HLA traits using the Med1 CDx DNA-based NGS panel targeting 601 cancer-related genes and HLA class I. TMB was calculated as the average number of coding mutations per megabase of the genome. HLA class I alleles (HLA-A, B and C) were identified and predicted using the OptiType and pVACtools software suites. TNB was defined as the number of high-affinity (IC50 ≤ 50 nM) neoantigens per megabase of the genome. Statistical analyses were performed to explore the relationship between TMB, TNB, and LOH status in critical regions of HLA. Results: This study enrolled participants across 25 cancer types. With 32.56% having non-small cell lung cancer (NSCLC), 11.79% colorectal carcinoma (CRC), and 18.34% unidentified solid tumors. The remaining 37.31% comprised cases of cholangiocarcinoma, hepatocellular carcinoma, pancreatic cancer, etc. High-affinity neoantigen-generating genes such as TP53, EGFR, KRAS, LRP1B, DMD, and FAT1 were identified. Our findings indicate substantial variation in tumor neoantigen burden (TNB) across various cancer types and even among different samples within the same type. Neuroendocrine tumors exhibited the highest TNB at 4 neoantigens/Mb, followed by esophageal cancer (3.3), melanoma and urothelial carcinoma (2.67 each), indicating higher TNB levels in these cancers compared to others. A significant positive correlation was observed between TMB and TNB (p< 0.0001). Analysis revealed no significant TNB differences attributable to age (cutoff at 60 years) or gender. However, individuals aged over 70 years demonstrated a higher TNB of 4 compared to those under 70 with 3.33, highlighting potential age-related differences in TNB. Conclusions: Our analysis highlights significant variation in TNB across cancer types, with the highest TNB found in neuroendocrine tumors and the lowest in gastrointestinal stromal tumors, indicating TNB's value as a biomarker for optimizing ICI therapy. Furthermore, we found that people over 70 years old have higher TNB levels than younger individuals, suggesting a potential for improved ICI efficacy without chemotherapy. The evident strong correlation between Tumor Mutational Burden (TMB) and TNB underlines their crucial role in the success of cancer immunotherapy.

Hairpin DNA-Based Nanomaterials for Tumor Targeting and Synergistic Therapy.

While nanoplatform-based cancer theranostics have been researched and investigated for many years, enhancing antitumor efficacy and reducing toxic side effects is still an essential problem. We exploited nanoparticle coordination between ferric (Fe2+) ions and telomerase-targeting hairpin DNA structures to encapsulate doxorubicin (DOX) and fabricated Fe2+-DNA@DOX nanoparticles (BDDF NPs). This work studied the NIR fluorescence imaging and pharmacokinetic studies targeting the ability and biodistribution of BDDF NPs. In vitro and vivo studies investigated the nano formula's toxicity, imaging, and synergistic therapeutic effects. The enhanced permeability and retention (EPR) effect and tumor targeting resulted in prolonged blood circulation times and high tumor accumulation. Significantly, BDDF NPs could reduce DOX-mediated cardiac toxicity by improving the antioxidation ability of cardiomyocytes based on the different telomerase activities and iron dependency in normal and tumor cells. The synergistic treatment efficacy is enhanced through Fe2+-mediated ferroptosis and the β-catenin/p53 pathway and improved the tumor inhibition rate. Harpin DNA-based nanoplatforms demonstrated prolonged blood circulation, tumor drug accumulation via telomerase-targeting, and synergistic therapy to improve antitumor drug efficacy. Our work sheds new light on nanomaterials for future synergistic chemotherapy.

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 .

Evaluation of the Expression EGFR, HER2/NEU and the End Effector ERK of the RAS/RAF/MAP Kinase Pathway in Prostatic Adenocarcinoma for a Possible Role as New Target Therapy.

Immunohistochemistry- using tissue microarrays- for EGFR, HER2/neu, non-phosphorylated, and phosphor-ERK, was performed on tissues from 166 patients- with primary prostatic adenocarcinoma with no prior treatment-. The results of different markers expression were correlated with the clinical and pathological parameters and were analyzed statistically. The prostatic tissue showed EGFR, HER2 neu, phosphorylated and non-phosphorylated ERK expression in 8.4%, 1.4%, 78.2%, and 83.4% respectively whether low (patchy) or high expression (diffuse). There were no significant correlations found between patient characteristics and expression of the tested markers. The negative immune reactivity for non-phosphorylated ERK and EGFR- was significantly correlated with high tumor stage (p values 0.03 and 0.01, respectively). EGFR and HER2/neu may play a limited role in prostatic adenocarcinoma as they showed positive expression in a limited number of the examined tissues specifically HER2neu. The expression of non-phosphorylated ERK (mostly weak to moderate) and phosphorylated ERK (mostly moderate to strong)- was appreciated in most cases. Thus, we suggest that anti-EGFR drugs may have a limited role in the treatment of castrate-resistant prostate cancer, but anti-MEK/ERK drugs may have more promising role as a target therapy. It is recommended to perform further molecular testing to elucidate the exact mechanism and significance of these markers.

Genomic profile of Japanese patients with rare ductal adenocarcinoma of the prostate has high grade and poor prognostic aspects.

e17046 Background: Ductal adenocarcinoma (DAC) is a rare subtype of prostate cancer with unknown etiology and poor prognosis. Genomic profile analysis using next-generation sequencing has the potential to elucidate the pathogenesis of rare cancers. To date, some studies have investigated the genetic profile of the DAC genotype; however, no definitive findings have been obtained due to the small number of patients and limited geographic coverage. The discovery of novel prognostic biomarkers and identification of new pharmacotherapeutic targets for DAC are currently of research interest. The aim of this study is to analyze the genomic profile of DAC in a Japanese population and to summarize its features. Methods: Clinical and histopathological records from our three hospitals were searched for radical prostatectomy, transurethral resection of the prostate, and prostate needle biopsy specimens containing a DAC component in the past 10 years. Twenty-eight patients diagnosed with DAC of the prostate were identified, of whom 15 were eligible for genomic profile analysis and 10 patients (66.7%) had the pure type. Genomic evaluation was performed using either the FoundationOne CDx or PleSSision testing platform. Results: At least one genomic alteration occurred in 14 patients (93.3%), and the most frequently mutated gene was tumor suppressor protein p53 ( TP53), which was found in seven cases (46.7%). Additionally, five cases (33.3%) had mutations in retinoblastoma transcriptional corepressor 1 ( RB1), and all these patients had the pure type. Four cases had both TP53 and RB1 alterations, and most of these possessed the pure type and had PSA levels of less than 4.0. Compared to previous study results, the frequency of genetic alterations in the phosphoinositide 3-kinase (PI3K) pathway (n = 3; 20.0%) and Wnt-β/catenin pathway (n = 6; 40.0%) was comparable, but alterations in the DNA damage repair (DDR) pathway were few (n=1; 6.7%). None of the patients presented high tumor mutation burden or microsatellite instability. Conclusions: We found that the Japanese cohort with DAC has unique features such as high frequency of alterations in tumor suppressor gene such as TP53 and RB1, and few DDR pathway alterations, suggesting the existence of regional and racial differences in genomic profiles. Genomic analysis using next-generation sequencing is expected to be useful in elucidating the pathogenesis of DAC, and further accumulation of cases is considered important.