Archival Tumor Research Articles

Combinatory analysis of immune cell subsets and tumor-specific genetic variants can predict clinical response to PD-1 blockade for non-small cell lung cancer patients

Abstract Blockade of PD-1/PDL1 (PD-1 blockade) with antibodies has revolutionized treatment options for non-small cell lung cancer (NSCLC) patients with tumors without targetable mutations. The benefit of PD-1 blockade is limited only to a subset of the patients. This study aims to identify biological markers of clinical response in a discovery cohort (n=15) of patients early during treatment to distinguish responders from nonresponders using immunological and genetic markers. Immune subsets identified in the blood are characterized to establish a panel of immune markers that could distinguish the two. Blood drawn from NSCLC patients before and after PD-1 blockade was analyzed by clinical flow cytometric assay for changes in the frequencies and concentration of immune cell populations. Next generation sequencing was performed on the extracted DNA from archival tumor biopsies from the same patients. irRECIST criteria was used to evaluate the clinical responses with cut-off at 10 months. Responders had a significantly increased frequency of activated effector memory CD4 & CD8 T cells & decreased frequency of central memory CD4 & CD8 T cells in circulation post-treatment compared to pre-treatment. In a separate cohort we validate initial findings in a cohort of n=29 & observe that effector memory CD8 T cells in responders produced high TNFα at pretreatment. Pathogenic & likely-pathogenic mutations in TP53, KRAS, KEAP1, NOTCH-1 and STK11 in the patients that responded to PD-1 blockade are observed. A multivariate analysis combining immune and genetic parameters could discriminate responders from non-responders. We report that combined analyses of selected immune cell & genetic parameters could predict early clinical response to PD-1 blockade.

HOPE (SOLTI-1903) breast cancer study: real-world, patient-centric, clinical practice study to assess the impact of genomic data on next treatment decision-choice in patients with locally advanced or metastatic breast cancer.

Metastatic breast cancer (mBC) causes nearly all BC-related deaths. Next-generation sequencing (NGS) technologies allow for the application of personalized medicine using targeted therapies that could improve patients' outcomes. However, NGS is not routinely used in the clinical practice and its cost induces access-inequity among patients. We hypothesized that promoting active patient participation in the management of their disease offering access to NGS testing and to the subsequent medical interpretation and recommendations provided by a multidisciplinary molecular advisory board (MAB) could contribute to progressively overcome this challenge. We designed HOPE (SOLTI-1903) breast cancer trial, a study where patients voluntarily lead their inclusion through a digital tool (DT). The main objectives of HOPE study are to empower mBC patients, gather real-world data on the use of molecular information in the management of mBC and to generate evidence to assess the clinical utility for healthcare systems. After self-registration through the DT, the study team validates eligibility criteria and assists patients with mBC in the subsequent steps. Patients get access to the information sheet and sign the informed consent form through an advanced digital signature. Afterwards, they provide the most recent (preferably) metastatic archival tumor sample for DNA-sequencing and a blood sample obtained at the time of disease progression for ctDNA analysis. Paired results are reviewed by the MAB, considering patient's medical history. The MAB provides a further interpretation of molecular results and potential treatment recommendations, including ongoing clinical trials and further (germline) genetic testing. Participants self-document their treatment and disease evolution for the next 2 years. Patients are encouraged to involve their physicians in the study. HOPE also includes a patient empowerment program with educational workshops and videos about mBC and precision medicine in oncology. The primary endpoint of the study was to describe the feasibility of a patient-centric precision oncology program in mBC patients when a comprehensive genomic profile is available to decide on a subsequent line of treatment. www.soltihope.com, identifier NCT04497285.

Two staged phase II clinical trial of Eribulin monotherapy in advanced or recurrent cervical cancer

BackgroundEribulin a microtubule targeting agent and analog of Halichondrin B, a natural product isolated from marine sponge H. okadai, has proven clinical efficacy in metastatic pretreated breast cancer and liposarcoma. We conducted a 2-stage Phase II study of eribulin in patients with advanced/recurrent cervical cancer to examine its clinical activity and evaluate biomarkers for predictors of response. MethodsWomen with advanced/recurrent cervical cancer after ≤1 prior chemotherapy regimen, measurable disease and ECOG performance status ≤2 were treated with eribulin (1.4 mg/m2 IV day 1 and 8, every 21 days) with tumor assessments every 2 cycles. Primary endpoint was 6-month progression-free survival (PFS6); secondary were best overall response (RECISTv1.1), toxicity (CTCAEv4.03) and overall survival (OS). Exploratory endpoints were associations of biomarkers with clinical activity. Immunohistochemistry was performed on archival tumor samples. Overexpression was defined when both intensity and distribution scores were ≥ 2. Results32 patients enrolled from 11/2012–5/2017. 29/32 patients had prior chemotherapy with cisplatin/paclitaxel/bevacizumab (n = 12) or cisplatin/gemcitabine (n = 12) as the most common regimens. 14 patients received prior paclitaxel. 1 (3%) had a complete response, 5 (16%) had a partial response and 13 (41%) had stable disease for ORR of 19% (95% CI 8, 37). Those who are paclitaxel naïve experienced the greatest benefit with a 29% ORR (95% CI 12, 54). Patients who received prior paclitaxel responded less favorably than those who did not (p = .002) and had a shorter PFS and OS. Grade 3/4 adverse events occurring in >10% of patients were anemia (n = 12, 38%), neutropenia (n = 7, 22%) and leukopenia (n = 6, 19%). Analysis of correlative predictors of response revealed that patients who did not overexpress βII and BAX were significantly more likely to respond to e`ribulin. PFS was significantly shorter in patients with βII and BAX overexpression, OS was significantly shorter in those with βIII and BAX overexpression. These associations remained after multivariate analysis. ConclusionsEribulin shows modest activity in patients with recurrent/advanced cervical cancer with a favorable toxicity profile. Prior paclitaxel exposure is associated with decreased eribulin response. βII, βIII tubulin subtypes and BAX are predictors of response and survival. Eribulin may be an option for women with paclitaxel-naïve recurrent/advanced cervical cancer.

Abstract CT133: Trial in progress: a multicenter phase 1/1b dose escalation study of WTX-124 as a monotherapy and in combination with pembrolizumab in patients with selected advanced or metastatic solid tumors

Abstract Background: High-dose recombinant human IL-2 (HD IL-2) is an FDA-approved therapy that produces durable complete remissions in a subset of patients with advanced or metastatic cutaneous melanoma and renal cell carcinoma. However, the clinical benefit of HD IL-2 is counterbalanced by life-threatening toxicities such as capillary leak syndrome. WTX-124 is an engineered cytokine prodrug composed of a wild-type IL-2 fused via proprietary cleavable linkers to an inactivation domain and to a half-life extension domain. In the circulation and in normal tissues, WTX-124 is designed to remain inactive and not bind to high- (αβγ) and intermediate-affinity (βγ) IL-2 receptors. In contrast, proteolytic activation of WTX-124 in the tumor microenvironment (TME) is expected to liberate the IL-2 cytokine to stimulate antitumor immune responses. Preclinical data show that WTX-124 is activated by a range of dissociated human tumors in vitro but not by normal human cells or by patient serum. Moreover, WTX-124 demonstrates potent antitumor activity in multiple murine syngeneic tumor models with substantial expansion and activation of tumor-infiltrating lymphocytes. In the MC38 model, WTX-124 has a large therapeutic window of >19-fold compared to ~3-fold for recombinant human IL-2. Methods: This first-in-human, open-label phase 1/1b trial is investigating the safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity of WTX-124 administered as a monotherapy or in combination with the anti-PD-1 antibody pembrolizumab to patients with advanced or metastatic solid tumors (NCT05479812). All patients must have ≥ 1 measurable lesion per RECIST 1.1 and a tumor type for which immune checkpoint inhibitor (ICI) therapy is indicated. Dose escalation uses a modified toxicity probability interval-2 study design with WTX-124 administered intravenously (IV) every two weeks in 28-day cycles. If the safety of WTX-124 as a monotherapy is established in the first three cohorts, the study will then initiate dose escalation of WTX-124 in combination with pembrolizumab 400mg IV every six weeks. Dose expansion is anticipated to include four arms that will enroll patients with either advanced or metastatic cutaneous melanoma or renal cell carcinoma to receive WTX-124 monotherapy or combination therapy (N=20 patients per arm). Patients with melanoma assigned to the WTX-124/pembrolizumab combination arm may be naïve to all prior systemic therapy for advanced disease, but all other patients in expansion must have previously received a standard of care ICI regimen. Pre- and on-treatment tumor biopsies, archival tumor tissue, and blood samples will be used to investigate multiple exploratory biomarkers. As of January 12, 2023, WTX-124 monotherapy dose escalation is proceeding. Citation Format: Ildefonso Ismael Rodriguez-Rivera, Justin C. Moser, Mateusz Opyrchal, Brendan Curti, Mehmet A. Bilen, Saero Park, Marissa Bruno, Paul Windt, Kulandayan K. Subramanian, Sameer S. Chopra, Randi Isaacs. Trial in progress: a multicenter phase 1/1b dose escalation study of WTX-124 as a monotherapy and in combination with pembrolizumab in patients with selected advanced or metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT133.

Abstract CT254: Trial in progress: a first-in-human, phase 1, multicenter dose escalation and dose expansion study of WTX-330 in adult patients with advanced or metastatic solid tumors or non-Hodgkin lymphoma

Abstract Background: Interleukin-12 (IL-12) is a potent proinflammatory cytokine with activating effects on both innate and adaptive immune cells. Though recombinant IL-12 (rIL-12) causes tumor regression with antitumor immune memory formation in a range of immunocompetent mouse models, clinical development of rIL-12 was limited by serious toxicities resulting in several patient deaths. WTX-330 is an engineered cytokine prodrug composed of a wild-type IL-12 heterodimer fused via proprietary cleavable linkers to an inactivation domain and to a half-life extension domain. In the circulation and in normal tissues, WTX-330 is designed to remain inactive and not bind to high-affinity IL-12 receptors. In contrast, proteolytic activation of WTX-330 in the tumor microenvironment is expected to liberate the IL-12 cytokine to stimulate antitumor immunity. Preclinical data show that WTX-330 is activated by a range of dissociated human tumors in vitro but not by normal human cells or by patient serum. Moreover, a WTX-330 murine surrogate molecule has potent antitumor activity as a monotherapy in multiple syngeneic mouse models, including in those resistant to anti-PD-1 therapy. In the MC38 model, the WTX-330 surrogate has a large therapeutic window of 49-fold compared to 5-fold for recombinant chimeric IL-12. Methods: This first-in-human, open-label phase 1 trial is investigating the safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity of WTX-330 administered as a monotherapy to patients with advanced or metastatic solid tumors or non-Hodgkin lymphoma (NCT05678998). All patients must have ≥ 1 measurable lesion per RECIST 1.1 and be refractory to all standard of care therapies for their indication. Dose escalation utilizes a Bayesian logistic regression model with overdose control with WTX-330 administered intravenously every two weeks in 28-day cycles. Dose expansion is anticipated to include two arms (A, B) of 20 patients each. Patients eligible for Arm A will have tumor types for which immune checkpoint inhibitors (ICIs) are indicated but demonstrate either primary or secondary resistance to this therapy. Primary resistance is defined as disease progression or SD < 6 months as the best response after at least 6 weeks of exposure to PD-(L)1 inhibitors. Secondary resistance is defined as disease progression ≥ 6 months after initiation of PD-(L)1 inhibitors in patients who received clinical benefit (i.e., CR, PR, or SD > 6 months). Patients eligible for Arm B will have any solid tumor for which ICI therapy is not indicated, or non-Hodgkin lymphoma. Pre- and on-treatment tumor biopsies, archival tumor tissue, and blood samples will be assayed for a range of exploratory biomarkers. As of January 12, 2023, the trial is opening sites and recruiting patients. Citation Format: Ildefonso Ismael Rodriguez-Rivera, Justin C. Moser, Mateusz Opyrchal, Aparna R. Parikh, Saero Park, Marissa Bruno, Paul Windt, Kulandayan K. Subramanian, Sameer S. Chopra, Randi Isaacs. Trial in progress: a first-in-human, phase 1, multicenter dose escalation and dose expansion study of WTX-330 in adult patients with advanced or metastatic solid tumors or non-Hodgkin lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT254.

Abstract CT189: A phase I study of BAT1006, a novel anti-HER2 antibody, in patients with locally advanced/metastatic solid tumors

Abstract Purpose: BAT1006 is a HER2 extracellular domain II-targeted monoclonal antibody with enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) effect aiming for Her2-positive locally advanced/metastatic solid tumors. Previous studies have shown that de-fucosylated antibody binds to FcγRIIIa with increased affinity and can thus trigger FcγRIIIa-mediated effector functions more efficiently than native antibody. BAT1006 was expressed in an FUT8-knockout CHO cell line, resulting in antibody completely devoid of fucose modification. With approximate 5-fold higher level of ADCC effect compared to Pertuzumab, BAT1006 also exhibited potent anti-tumor activity in HER2 positive Calu-3 xenograft mice model. The ongoing phase I, open-label, first-in-human study is evaluating the safety, pharmacokinetics (PK), immunogenicity and preliminary efficacy of BAT1006 to determine the Maximum-Tolerated Dose (MTD) and/or recommended phase II dose (RP2D). Methods: Patients with locally advanced/metastatic solid tumors received escalating doses of BAT1006 (3, 6, 10, 15 mg/kg), administered intravenously (IV) once every three weeks. Patients must have had documented HER2 positivity defined as 3+ by validated immunohistochemistry or amplified on in situ hybridization (ISH). Assessments include archival tumor molecular status, PK, and efficacy by Response Evaluation Criteria in Solid Tumors (RECIST). Results: Fifteen patients [with 2-9 prior lines of therapy] have been treated with BAT1006. All patients had metastatic breast cancer and had received previous HER2-targeted therapies including Trastuzumab, Pertuzumab, T-DM1 and Pyrotinib. No treatment related ≥ Grade 3 AEs have been observed. Of 9 patients at 10mg/kg and 15mg/kg, 1 in 3 patients had CR at 10mg/kg, 2 in 6 patients had PR at 15mg/kg. Conclusion: BAT1006 was well tolerated and showed promising anti-tumor activity in patients with heavily pre-treated HER2-positive cancers. Based on the safety and efficacy results, one additional dose level (20 mg/kg) will be added to the escalation phase and combination therapy with other HER2-based therapy will also be initiated. Citation Format: Xingxing Mei, Weijia Tang, Shuqiang Song, Hao Wang, Chuanqi Cao, Cuiying Feng, Bert E. Thomas, Shengfeng Li, Jin-Chen Yu. A phase I study of BAT1006, a novel anti-HER2 antibody, in patients with locally advanced/metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT189.

Abstract CT177: A phase I, first in human study of CBA-1205, glycoengineered humanized anti-DLK-1 monoclonal antibody in patients with advanced solid tumors

Abstract Background: CBA-1205 is a novel humanized anti-delta-like 1 homolog (DLK-1) antibody. It is a glycoengineered antibody by GlymaxX® technology to potentiate antibody-dependent cellular cytotoxicity activity. DLK-1 is a membrane protein with 6 tandem EGF-like motifs in extracellular region. Overexpression of DLK-1 has been reported in variety of cancer types including hepatocellular carcinoma (HCC), suggesting that DLK-1 could be an ideal target for cancer therapy. Methods: This is a first in human, multicenter, open-label Phase I study. The purpose of part 1 is to evaluate the safety and tolerability in patients with advanced solid tumors who had no standard therapy or were refractory or intolerant to standard therapies and to determine the starting dose for part 2 in HCC patients. The standard 3+3 dose escalation design was utilized in seven cohorts (0.1, 0.3, 1, 3, 10, 20, 30 mg/kg). CBA-1205 was administered at 2-week intervals in a 28-day cycle. If the patient had no Dose Limiting Toxicity (DLT) during 28 days after the first two doses, CBA-1205 administration will be continued for further cycles unless any of the criteria for discontinuation. Serum DLK-1 concentration before the start of CBA-1205 administration was analyzed using the Human Pref-1/DLK1/FA1 DuoSet ELISA (R&D Systems, Inc.). Immunohistochemical analysis of DLK-1 expression in the archival tumor specimen was determined in FFPE tissue sections using mouse anti-hDLK-1 antibody (clone DI-2-20, Chiome Bioscience). Results: 22 patients with advanced solid tumors were enrolled. CBA-1205 was well tolerated in these patients and no DLT was observed even at the highest dose tested. No ≥ Grade 3 treatment related adverse events was observed throughout the study periods. The serum concentration of CBA-1205 increased dose-proportionally. The exposure to CBA-1205 exceeded the effective concentrations observed in a mouse xenograft model. No serum anti-CBA-1205 antibody was detected. The disease control was seen in 8 patients (38.1%, all with SD). Especially, long SD was observed in 3 patients with invasive thymoma, malignant melanoma, and pancreatic carcinoma, where progression free survival (PFS) was 39, 72(ongoing, at data cutoff), and 41 weeks, respectively. The serum concentration of soluble DLK-1 was detected in 6 out of 22 patients. Patients with SD by the best overall response had a higher rate of detectable serum DLK-1 concentration and a higher mean concentration than patients with PD. No DLK-1 expression in tumor was detected by IHC method, in 14 patients who consented to use the archival tumor specimens. Conclusions: CBA-1205 was well tolerated without any severe toxicity in patients with advanced solid tumors.Part 2 of this Phase I study with two cohorts (20, 30 mg/kg) in patients with unresectable advanced/recurrent HCC refractory or intolerable to the standard therapy has been initiated. Citation Format: Masafumi Ikeda, Nobuaki Matsubara, Chihiro Kondoh, shose taoka, Yuki Katsuya, Takafumi Koyama, Noboru Yamamoto. A phase I, first in human study of CBA-1205, glycoengineered humanized anti-DLK-1 monoclonal antibody in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT177.

Abstract CT082: Next-generation sequencing (NGS) and cytokine assessment from a phase III study of copanlisib in combination with rituximab in patients with indolent non-Hodgkin lymphoma (iNHL) - associations with survival endpoints

Abstract Introduction: The PI3K inhibitor copanlisib (C) plus the anti-CD20 antibody rituximab (R) was superior to R plus placebo (P) in patients (pts) with relapsed iNHL (Matasar et al. Lancet Oncol 2021). We previously reported that C+R improved median progression-free survival (PFS) in the iNHL, follicular lymphoma (FL), and non-FL groups, with a statistically significant improvement in the PTEN-positive population (Shalini et al., AACR 2022). Here we conducted NGS analysis from pts treated with either C+R or P+R for possible impact on PFS outcomes. We also determined if there was an association between plasma cytokine levels at baseline with survival. Methods: Adult pts with relapsed B-cell iNHL were randomly assigned 2:1 to either C+R or P+R; standard dosing on a 28-day cycle applied. Either fresh or archival tumor tissues were collected for central pathology review and biomarker analysis. NGS was conducted using the TSO500 platform for 476 genes. Analyses included EZH2 and BCL2 mutation status in FL subset, and other genes for FL subsets and overall iNHL, as prognostic and predictive markers. The effect of mutations on PFS and overall survival (OS) outcomes was assessed. Cytokines from baseline plasma were assessed using the multiplex MSD platform (71-plex). Association between cytokine levels and PFS and OS were explored. Results: Baseline tumor samples were evaluable by NGS from 200 pts; 127 C+R and 73 P+R. Variant alleles with frequencies >10% were analyzed. One quarter (25.7%) of FL pts were determined to have EZH2 mutations. C+R treatment significantly improved PFS for FL pts with in mutant EZH2 (p=0.0066) compared to P+R. FL pts with mutant BCL2 had a statistically improved PFS compared to WT BCL2 when receiving C+R treatment. Plasma samples were available for 71-plex assessment in 373 pts; 246 C+R and 127 P+R. Pts were assigned as high or low baseline cytokine groups based on the median values. For majority of cytokines, the low cytokine group correlated with better PFS for all pts, FL and Other iNHL pts in the C+R arm. For OS, there were too few events at the time of primary data cutoff to make any associations. However, with longer follow up (2 years from primary completion) there was a significant improvement in OS in iNHL pts with low IL2 values at baseline receiving C+R compared to pts receiving P+R; HR 0.495 (95%CI: 0.270,0.908), p=0.0230. This association was only seen for pts with low (or undetected) levels of IL2 at baseline. Conclusions: Mutation status was associated with improvements in PFS in FL pts with mutant BCL2 or mutant EZH2 treated with C+R. iNHL pts with low plasma levels of IL2 levels treated with C+R showed a significant improvement in OS. Citation Format: Shalini Chaturvedi, Anke Weispfenning, David Bauer, Rong Du, Tine Descamps, Sara Bellinvia, Teresa Lunt, Lidia Mongay Soler, Barrett H. Childs, Pier Luigi Zinzani. Next-generation sequencing (NGS) and cytokine assessment from a phase III study of copanlisib in combination with rituximab in patients with indolent non-Hodgkin lymphoma (iNHL) - associations with survival endpoints [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT082.

Abstract CT213: Biomarker analysis from Phase 1/2 study of tusamitamab ravtansine (SAR408701) in patients with advanced non-small cell lung cancer (NSCLC)

Abstract Background Tusamitamab ravtansine is an antibody-drug conjugate of a humanized carcinoembryonic antigen (CEA)-related cell adhesion molecule 5 (CEACAM5)-specific monoclonal antibody linked to DM4. A Phase 1/2 study (NCT02187848) showed tusamitamab ravtansine antitumor activity in pretreated patients (pts) with advanced nonsquamous NSCLC and high CEACAM5 expression. Here, we explore biomarker associations with tumor CEACAM5 expression by immunohistochemistry (IHC), and whether biomarkers predict objective response rate (ORR). Methods We assessed CEACAM5 expression by IHC, RNA sequencing, and whole exome sequencing (WES) on latest archival tumor samples; and circulating CEACAM5 (cCEACAM5) and CEA (cCEA). We enrolled 2 cohorts of pts with IHC CEACAM5 membrane expression at ≥2+ intensity: in ≥50% of tumor cells (high expressors, HEs, n = 64); and in ≥1% to <50% of tumor cells (moderate expressors, MEs, n = 28). Pts received tusamitamab ravtansine 100 mg/m2 IV every 2 weeks. Results cCEA and cCEACAM5 were strongly associated (Spearman rho, 0.9), with weak associations between IHC CEACAM5 and cCEA or cCEACAM5 (Spearman rho, 0.3 and 0.4, respectively). Higher levels of CEACAM5 mRNA were observed in CEACAM5 HEs vs MEs (P=0.0027). EGFR and KRAS genetic alterations by WES were present in 44.8% and 65.5% of CEACAM5 HEs, respectively, and 21.4% and 78.6% of CEACAM5 MEs, respectively. Confirmed partial responses were seen in 13/64 HEs (ORR 20.3%) and 2/28 MEs (ORR 7.1%). In CEACAM5 HEs with available baseline (BL) cCEA data, 25/62 (40.3%) had a cCEA level ≥100 µg/L, with a median value of 71.6 µg/L (range 1-8809); corresponding values in CEACAM5 MEs were 7/28 (25.0%) and 12.4 µg/L (range 0.5-684). In response evaluable CEACAM5 HEs with available BL cCEA data (n = 61), ORR was 10/24 (41.7%) in pts with high cCEA (≥100 µg/L) and 3/37 (8.1%) in pts with low cCEA (<100 µg/L); corresponding ORRs in CEACAM5 MEs were 0/7 and 2/21 (9.5%). Conclusions In CEACAM5 HEs, high cCEA was associated with numerically greater ORR vs low cCEA (41.7% vs 8.1%). Associations were also observed between: cCEA and cCEACAM5; IHC CEACAM5, cCEA, and cCEACAM5; and IHC CEACAM5 and CEACAM5 tumor mRNA levels, but not between IHC CEACAM5 and actionable oncogenic drivers. Clinical Trials Registration: ClinicalTrials.gov NCT02187848 Citation Format: Anas Gazzah, Joon Sang Lee, Emma Wang, Nils Ternès, Hong Wang, Eric Boitier, Aude Lartigau, Mustapha Chadjaa, Colette Dib, Gaëlle Muzard, Sandrine Valence, Anne Remaury, Cintia C. Palu, Anne-Laure Bauchet. Biomarker analysis from Phase 1/2 study of tusamitamab ravtansine (SAR408701) in patients with advanced non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT213.

PSMA Expression Correlates with Improved Overall Survival and VEGF Expression in Glioblastoma.

Glioblastomas are the most common and fatal primary brain malignancy in adults. There is a growing interest in identifying the molecular mechanisms of these tumors to develop novel treatments. Glioblastoma neo-angiogenesis is driven by VEGF, and another potential molecule linked to angiogenesis is PSMA. Our study suggests the potential for an association between PSMA and VEGF expression in glioblastoma neo-vasculature. Archived IDH1/2 wild-type glioblastomas were accessed; demographic and clinical outcomes were recorded. PSMA and VEGF expression by IHC were examined. Patients were dichotomized into PSMA expression high (3+) and low (0-2+) groups. The association between PSMA and VEGF expression was evaluated using Chi2 analysis. OS in PSMA high and low expression groups were compared using multi-linear regression. In total, 247 patients with IDH1/2 wild-type glioblastoma with archival tumor samples (between 2009-2014) were examined. PSMA expression correlated positively with VEGF expression (p = 0.01). We detected a significant difference in median OS between PSMA vascular endothelial expression high and low groups-16.1 and 10.8 months, respectively (p = 0.02). We found a potential positive correlation between PSMA and VEGF expression. Secondly, we showed a potential positive correlation between PSMA expression and overall survival.

Abstract 1169: Genomic evolution of pancreatic cancer at single-cell resolution

Abstract As the breadth of genomic sequencing datasets increases, we can engage more directly with the evolutionary principles governing cancer progression. But as clonal evolution happens at the single-cell level, one must rely on strong assumptions when making conclusions with bulk-sequencing results, which fails in capturing clonal heterogeneity to its fullest. Herein we have developed and optimized a high-throughput, high-depth targeted single-nucleus DNA-seq (snDNA-seq) technique (doi.org/10.1101/2022.03.06.483206) for archival primary solid tumor samples. We focused on pancreatic ductal adenocarcinoma (PDAC), well known as one of the most lethal cancers, and sequenced over 200,000 single nuclei from 80 archival primary samples of 25 PDAC patients. The samples included both early- and late-stage diagnoses and multiregional sampling from primary tumors and metastasis to capture clonal heterogeneity on both temporal and spatial scales. With significant increase in sensitivity than bulk (down to mutations in 0.1% cells), we discovered thousands of novel mutations per sample on our 120,000 base-pair-long panel regions, suggesting a mutation rate higher than previously estimated. A small fraction of these mutations is in 1-10% single cells and are enriched in early-stage samples. They form mutually exclusive clones which functionally target key pathways including TGF-β, homologous recombination, suggesting subclonal evolution under positive selection at the early stage of cancer. Most novel mutations are in <1% single cells sampled and enabled us to measure convergent evolution and positive/negative selection within each tumor. We next revisited PDAC’s genomic evolution model established by bulk studies. It posits that PDAC often arises when KRAS hotspot mutation-bearing precursors acquire TP53 and/or CDKN2A inactivation through stepwise and punctuated evolution. While it assumes that TGF-β inactivating mutations are present in all cancer cells (clonal), we found that they are targeted in a highly subclonal manner; moreover, short mutations and focal copy number variations occur in a stepwise manner over time leading to the most “fit” genotype. In many PDACs whose bulk results show no alteration to the TGF-β pathway, snDNA-seq shows focal deletions that are likely below bulk’s sensitivity. Ongoing studies have begun to extend these analyses to longitudinal samples to study treatment response; normal pancreas tissues to study pancreas cells’ clonal evolution in aging and chronic disease conditions; blood samples to investigate circulating tumor cells in PDAC patients. Computational pipelines and analysis tools are being built as platform for more in-depth analyses. Overall, the high-throughput snDNA-seq technique brings genomic study of PDAC to a much higher resolution and holds the promise to not only inform precision medicine but also shed light on many fundamental questions on cancer evolution. Citation Format: Haochen Zhang, Palash Sashittal, Elias-Ramzey Karnoub, Benjamin J. Raphael, Christine A. Iacobuzio-Donahue. Genomic evolution of pancreatic cancer at single-cell resolution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1169.

Abstract 2173: A multi-institutional prospective biomarker study of durvalumab after concurrent chemoradiation therapy in patients with unresectable stage III non-small cell lung cancer (WJOG11518L/SUBMARINE)

Abstract Background: Programmed cell death-ligand 1 (PD-L1) inhibitor durvalumab has been found to improve disease control in patients with unresectable stage III non-small cell lung cancer (NSCLC) treated with definitive concurrent chemoradiation therapy (dCCRT), but approximately a half of patients eventually experience disease progression within one year after the start of durvalumab. The mechanism of this resistance at such an early timing is poorly identified. Therefore, we conducted a prospective biomarker study to explore the resistance mechanisms to durvalumab after CCRT (Trial Identifier: UMIN000035916). Methods: A total of 139 patients with unresectable stage III NSCLC enrolled into this study after dCCRT were treated with durvalumab for up to 1 year. 135 patients who fulfilled the predetermined selection criteria were included for this primary biomarker analysis. Archival tumor tissues collected before the treatment were analyzed by immunohistochemistry for several key biomarkers such as PD-L1, CD8, and CD73, DNA sequencing for tumor-mutation burden (TMB) and genomic profile, as well as gene expression profiling (GEP). Peripheral blood mononuclear cells (PBMC) were also collected before and after durvalumab for flow-cytometry (FCM) analysis where available. Progression-free survival (PFS) was compared based on these biomarkers. Results: Median follow-up time was 14.4 months. Median PFS was 14.9 months (95% confidence interval [CI], 11.3-not reached), and 1-year PFS rate was 56.3% (95% CI, 47.3-64.3). CD8+ tumor-infiltrating lymphocytes (TILs), PD-L1 tumor proportion score (TPS), TMB, and CD73 on tumor cells were associated with PFS (hazard ratios [HRs], 0.40 [95% CI, 0.22-0.73] for CD8+TILs; 0.67 [95% CI, 0.40-1.11] for PD-L1-TPS ≥1%; 0.59 [95% CI, 0.34-1.02] for high TMB; 1.45 [95% CI, 0.86-2.43] for high CD73). Common pathogenic gene alterations such as EGFR, KRAS, and TP53 were not associated with PFS. Multivariable analysis including key clinical factors as covariables indicated that CD8+TILs and the CD73-expressing tumor cells were independently associated with durvalumab outcome (HRs, 0.26 [95% CI, 0.08-0.89] for CD8+TILs; 5.83 [95% CI, 1.33-25.62] for CD73). The significance of CD73-expressing tumor cells as a resistance factor was more obvious in patients with high CD8+TILs (HR, 2.35 [95% CI, 1.14-4.86]). GEP of tumor tissue and FCM of PBMC suggested that CD73-expressing tumor cells prevented effective reinvigoration of antigen-reactive CD8+ T cells by durvalumab due to the immunosuppressive activity. Conclusions: Low preexisting CD8+TILs or high CD73-expressing tumor cells were suggested to be primary resistance mechanism to durvalumab after CCRT in stage III NSCLC. Further development of next treatment approach will be prompted based on these findings. Citation Format: Koji Haratani, Atsushi Nakamura, Nobuaki Mamesaya, Kenji Sawa, Yasuto Yoneshima, Ryota Saito, Tomohiro Ozaki, Kenjiro Tsuruoka, Akito Hata, Kosuke Tsuruno, Tomohiro Sakamoto, Shunsuke Teraoka, Masahide Oki, Hiroshi Watanabe, Tomoyuki Otani, Kazuko Sakai, Shuta Tomida, Yasutaka Chiba, Akihiko Ito, Kazuto Nishio, Nobuyuki Yamamoto, Kazuhiko Nakagawa, Hidetoshi Hayashi. A multi-institutional prospective biomarker study of durvalumab after concurrent chemoradiation therapy in patients with unresectable stage III non-small cell lung cancer (WJOG11518L/SUBMARINE) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2173.

Abstract 6071: Whole-exome RNA sequencing of metastatic synovial sarcomas reveals heterogeneous transcriptomic profile and targetable co-alterations: Cohort study from the French Sarcoma Group

Abstract Introduction: Synovial Sarcoma (SS) is a rare and aggressive disease that predominantly occurs in young adult. SS are characterized by a pathognomonic t(X:18) translocation leading SS18: SSX1/2/4 fusion. Small studies (n<100) described molecular background beyond this fusion in patients and the transcriptomic profile of SS remains poorly known. The aim of our study is to provide a large cohort analyzing transcriptomic and co-alterations to better understand and treat SS. Methods: We present a clinico-biological cohort study including all adult patients with histologically confirmed diagnosis of afvanced SS from January 2000, registered in the French Sarcoma database (NETSARC+) and with available formalin-fixed paraffin embedded (FFPE) archival tumor samples and clinical data. FFPE tumor samples were analyzed by dedicated whole-exome RNA-sequencing (WERS) to assess transcriptomic, small nucleotide variation (SNV) and fusions. Results: 122 patients (133 samples) met the study criteria, including 11 patients with paired primary-metastatic tumor samples. Clinical characteristics (age, sex, tumor grade, primary and metastasis site distribution) were consistent with expected SS population. The SS18:SSX1/2/4 fusion was found in all patient (90% by WERS and if negative, by FISH). Unsupervised analyses of transcriptomic data by principal component analyses, hierarchical sample clustering or UMAP revealed heterogeneity in gene expression. Clinical factors (age, sex, grade, tumor type, complete response to treatment, survival) did not correlate with transcriptomic profiles. Immune cell analyses confirmed a low infiltration of immune cells, notably poor in CD8+ T cells. Cancer testis antigens such as NYESO-1, MAGE-A4 were both expressed with a heterogeneous co-expression of other CTAs across samples. In the 11 primary-metastatic paired- samples, no gene pathway was found differentially expressed between primary and metastatic samples cohort with the exception of lung tissue specific genes. Comparing chemotherapy-naïve versus pre-treated samples did not identify differential expression of specific genes across samples. Single Nucleotide Variant analyses was reliable on 84% FFPE samples and revealed an overall low Tumor Mutational Burden with some samples harboring canonical oncogene pathogenic mutations of BTK, RAS, NF1, RB1 as well as in DNA repair pathway(15% spanning over ATM ATR,CHK2, BRCA1/2 PALB2 CHK2, FANCM, RAD51), PI3K pathways (PI3KCA E545K) and other poorly described in SS. Conclusion: Investigating the largest cohort of metastatic SS by whole-exome RNA-sequencing, revealed Synovial Sarcoma, usually classified as “simple genomic sarcoma” is a translocation-related sarcoma harboring heterogeneous transcriptomic and numerous SNV co-alterations including targetable mutations. Citation Format: Helene Vanacker, Mehdi Brahmi, Yannick Le Meitour, Julien Bollard, Valery Attignon, Alexandra Meurgey, Myriam Jean-Denis, Laurie Tonon, Shibani Pokras, Erika Klohe, Michael Nathenson, Kristin Blouch, Ioanna Eleftheriadou, Jean-Yves Blay, Franck Tirode, Armelle Dufresne. Whole-exome RNA sequencing of metastatic synovial sarcomas reveals heterogeneous transcriptomic profile and targetable co-alterations: Cohort study from the French Sarcoma Group. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6071.

Lymphocyte-activating gene 3 expression in tumor cells predicts immune checkpoint inhibitor response in triple negative breast cancer.

Immune checkpoint inhibitor (ICI) is one of the standard treatment strategies in triple negative breast cancer (TNBC). However, the benefit of ICI with chemotherapy is limited in metastatic TNBC. In this study, we evaluated the effect of PD-L1 and LAG-3 expression on tissue microenvironment of mTNBC treated with ICI. We reviewed representative formalin-fixed paraffin embedded specimens from metastatic or archival tumor tissues of TNBCs who treated with PD-1/PD-L1 inhibitors in metastatic setting. We used the Opal multiplex Detection kit with six antibodies (anti-PD-L1, anti-LAG-3, anti-CD68, anti-panCK, anti-CD8, anti-CD107a/LAMP antibody). We evaluated the association between LAG-3+cells and survival outcome regarding CK expression. Stromal LAG-3+/CK+ and LAG-3+/CK- cells were not associated with ICI-progression free survival(PFS) (P=0.16). However, LAG-3+ cell distributions in the tumor area impacted on ICI-PFS. A high density of LAG-3+CK+ cells was associated with shorter ICI-PFS compared with low densities of both LAG-3+CK+ and LAG-3+CK- cells (1.9 vs. 3.5 months). In addition, a high density of LAG-3+CK- cells had a relatively longer ICI-PFS compared with other groups (P=0.01). In terms of total area, the pattern of densities of LAG-3+CK+ cells and LAG-3+CK- cells were similar to those in the tumor area In addition, ICI-PFS of LAG-3+CK- and LAG-3+CK+ cell densities in the total area was equal to that in the tumor area. In conclusion, our findings revealed tumor-intrinsic LAG-3 expression was the resistance mechanism toward PD-1/PD-L1 inhibitors in mTNBCs. Multivariate analysis also suggested that LAG-3 expression in tumor cells was an independent predictive biomarker.

Integrated genetic profiling of archival pediatric high-grade glial tumors and reassessment with 2021 WHO classification of paediatric CNS tumours

Though rare, pediatric high-grade gliomas (pHGG) are a leading cause of cancer-related mortality in children. We wanted to determine whether our currently available clinical laboratory methods could better define diagnosis for pHGG that had been archived at our institution for the past 20 years (1998 to 2017). We investigated 33 formalin-fixed paraffin-embedded pHGG using ThermoFisher Oncoscan SNP microarray with somatic mutation analysis, Sanger sequencing, and whole genome sequencing. These data were correlated with historical histopathological, chromosomal, clinical, and radiological data. Tumors were subsequently classified according to the 2021 WHO Classification of Paediatric CNS Tumours. All 33 tumors were found to have genetic aberrations that placed them within a 2021 WHO subtype and/or provided prognostic information; 6 tumors were upgraded from WHO CNS grade 3 to grade 4. New pHGG genetic features were found including two small cell glioblastomas with H3 G34 mutations not previously described; one tumor with STRN-NTRK2 fusion; and a congenital diffuse leptomeningeal glioneuronal tumor without a chromosomal 1p deletion but with KIAA1549-BRAF fusion. Overall, the combination of laboratory methods yielded key information for tumor classification. Thus, even small studies of these uncommon tumor types may yield new genetic features and possible new subtypes that warrant future investigations.

Abstract OT1-03-04: Datopotamab deruxtecan (Dato-DXd), a TROP2 antibody-drug conjugate, vs investigators’ choice of chemotherapy in previously-treated, inoperable or metastatic HR+/HER2– breast cancer: TROPION-Breast01

Abstract Background: Chemotherapy is the main treatment in patients with pre-treated endocrine-resistant HR+/HER2– metastatic breast cancer, but has limited efficacy and substantial toxicities. The antibody-drug conjugate Dato-DXd consists of a humanized IgG1 mAb targeting TROP2 attached via a stable cleavable linker to a topoisomerase I (TopI) inhibitor payload. Heavily pre-treated patients with metastatic triple-negative breast cancer in the TROPION-PanTumor01 (NCT03401385) study of Dato-DXd showed a manageable safety profile and highly encouraging objective response rates (ORR by blinded independent central review [BICR]: 34% in all patients; 52% in patients treatment-naïve to TopI inhibitor-based therapies). The metastatic HR+/HER2– breast cancer cohort of TROPION-PanTumor01 has completed enrollment (n=41); data are currently maturing. Trial design: TROPION-Breast01 (NCT05104866) is an ongoing, global, phase 3, open-label, randomized trial evaluating efficacy and safety of Dato-DXd vs investigators’ choice of chemotherapy (ICC) in patients with inoperable or metastatic HR+/HER2– breast cancer. Patients (n≈700) are randomized 1:1 to Dato-DXd 6 mg/kg IV Q3W or ICC (eribulin, capecitabine, vinorelbine, or gemcitabine) until progression. Adults with an ECOG performance status of 0–1, who experienced progression on or are unsuitable for endocrine therapy, and received 1–2 prior lines of standard-of-care chemotherapy in the inoperable or metastatic setting are eligible. Monotherapy treatment with inhibitors of mTOR, PD-[L]1, CDK4/6 and PARP do not count as prior chemotherapy lines. Patients must have ≥1 measurable lesion per RECIST 1.1 and an archival or fresh formalin-fixed and paraffin-embedded tumor sample. Clinically inactive brain metastases are permitted. Dual primary endpoints are progression-free survival (PFS) by BICR, and overall survival. Secondary endpoints include PFS per investigator, ORR, disease control rate, patient-reported outcomes, and Dato-DXd pharmacokinetics and immunogenicity. Exploratory endpoints include TROP2 expression and exposure–efficacy relationship. Patients are stratified by number of prior chemotherapy lines, prior CDK4/6 inhibitor use, and region. At the time of writing 236 patients have been enrolled across 19 countries. Citation Format: Aditya Bardia, Kevin Kalinsky, Junji Tsurutani, Erika Hamilton, Joo Hyuk Sohn, Kyong Hwa Park, Yeon Hee Park, Seock-Ah Im, Keun Seok Lee, Daisy Dastur, Vincent Haddad, Sabrina Khan, Binghe Xu, Barbara Pistilli, Hope Rugo. Datopotamab deruxtecan (Dato-DXd), a TROP2 antibody-drug conjugate, vs investigators’ choice of chemotherapy in previously-treated, inoperable or metastatic HR+/HER2– breast cancer: TROPION-Breast01 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-03-04.

Abstract OT2-16-02: Open-label, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with advanced/metastatic human epidermal growth factor receptor 2–positive breast cancer: DESTINY-Breast12

Abstract Background: Patients (pts) with human epidermal growth factor receptor 2–positive breast cancer (HER2+ BC) have a high incidence (up to 50%) of brain metastasis (BM) despite advances in treatment (Zimmer AS et al. Cancer Rep (Hoboken). 2020;e1274; Hurvitz SA et al. Clin Cancer Res. 2019;25:2433-2441). Although several agents have been studied in pts with HER2+ BC with BM, an unmet medical need remains. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a pt subgroup with stable BM (n=24), with a confirmed objective response rate (ORR) of 61.4%, an extracranial confirmed ORR by independent central review (ICR) of 58.3%, respectively, and median progression-free survival (PFS) of 19.4 and 18.1 months, respectively (Modi S et al. Cancer Res. 2021. Abst PD3-06; Jerusalem G et al. Ann Oncol. 2020. Abst 138O). T-DXd also demonstrated preliminary efficacy in a subgroup of pts with BM in the DESTINY-Breast03 trial, with an extracranial ORR of 67.4%, intracranial ORR of 63.9%, and median PFS of 15.0 months (Hurvitz S et al. SABCS 2021. Abst GS3-01). However, both trials excluded pts with active/progressive BM. Here we describe a trial evaluating T-DXd in a real-world setting in pts with stable or active BM and pts without BM with previously treated advanced/metastatic HER2+ BC. The data generated by this study will complement previous and ongoing studies, providing a more robust understanding of T-DXd treatment in patients with and without BM. Trial design: DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (91 sites in the US, Europe, Australia, Canada, and Japan), phase 3b/4 study assessing the efficacy and safety of T-DXd 5.4 mg/kg every 3 weeks in pts with HER2+ BC ± BM. As part of prescreening, all pts will provide informed consent for tumor tissue samples (archival tumor tissue or fresh biopsy) to be collected and tested for HER2 status. Pts will be enrolled in 1 of 2 cohorts (250 pts each): cohort 1 (no BM at baseline) and cohort 2 (BM at baseline). Pts must have previously treated HER2-positive BC that has progressed on or after ≥1 prior anti-HER2–based regimen (including disease progression ≤6 months after adjuvant treatment with HER2-targeted therapies) and received ≤2 lines of therapy in the metastatic setting (excluding pts with prior tucatinib). Cohort 1 will be limited to include ≤25% third-line pts. Pts with BM must have untreated BM not needing immediate local therapy or previously treated stable or progressing BM. Primary endpoints are ORR in cohort 1 and PFS in cohort 2 (both by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1 per ICR). Secondary endpoints in both cohorts are overall survival, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and quality of life. Incidence of new symptomatic central nervous system (CNS) metastasis is a secondary endpoint in cohort 1, and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNS metastasis are secondary endpoints in cohort 2. Citation Format: Nancy U. Lin, Eva Ciruelos, Guy Jerusalem, Volkmar Müller, Naoki Niikura, Giuseppe Viale, Emma Oscroft, Shawn Anand, Manoj Prahladan, Nadia Harbeck. Open-label, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with advanced/metastatic human epidermal growth factor receptor 2–positive breast cancer: DESTINY-Breast12 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-16-02.

Abstract P2-20-10: Prognostic impact of lymphocyte-Activation Gene-3 (LAG-3) expression in triple negative breast cancer

Abstract Introduction Recent advances in breast cancer treatment strategies have improved survival outcomes in metastatic breast cancer (mBC). Targeting immune checkpoint, especially programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1), has made a breakthrough in treating advanced malignancies including breast cancer. Immune checkpoint inhibitors (ICIs), such as pembrolizumab and atezolizumab, in combination with chemotherapy have prolonged survival outcomes in mBC with triple negative subtype. However, the low response rate and resistance of ICIs with anti-PD 1/PDL-1 antibodies is a major limitation and a challenge. Lymphocyte Activation Gene-3 (LAG3; CD223) is a potential cancer immunotherapeutic target due to its negative regulatory role on T cells and cytokines, thereby ensuring immune homeostasis. Several studies suggested that combination immunotherapy of anti-LAG-3 and anti-PD-1 has shown promising efficacy in fighting PD-1 resistance. Therefore, we evaluated the prognostic role of LAG3 in metastatic TNBC (mTNBC) treated with ICIs to figure out resistance mechanism of ICIs. Methods mTNBC patients with available archival tumor tissues, who has received ICIs in Samsung Medical Center, were enrolled in this study. For the evaluation of LAG3 expression in tumor microenvironment, Vectra Polaris Multispectral Imaging and Whole Slide Scanning technique (PerkinElmer, Inc. Hopkinton, MA) was used. Results In total, 64 mTNBC patients were treated with ICI’s with or without cytotoxic chemotherapy between 2019.02- 2021.11. Of 70 mTNBC patients, 41 patients had archival tissues and finally 40 patients were included in this study. Median age was 43.0 years of age (range: 24.5 ~ 64.5). Recurrent mTNBC was 92.5% and only 7.5% was de novo mTNBC. Geremline BRCA1 pathogenic variants were detected in 4 (10.0%) patients. Among 37 recurrent mTNBC patients, 72.5% were treated with neoadjuvant chemotherapy with anthracycline (97.3%) and taxane(97.3%). Among ICI’s, 52.5% were treated with pembrolizumab and 47.5% of atezolizumab. LAG3 expression varies among mTNBC tissues (median cell density: 366, range: 48, 2861 cells/mm2). Among cells expressing LAG3, LAG3 was expressed more in CK+ cells compared with CK- cells (median:150 (20, 2503) cells/mm2 in CK+ cells, median: 88 (2, 806) cells/mm2 in CK- cells, p=0.005). Patients with high LAG3 expression in CK+ cells showed short progression free survival(PFS) compared to those with low LAG3 expression in CK+ cells (median PFS of high vs. low LAG3 expression [months]:1.9 vs. 4.2, p=0.01). On the contrary, patients with high LAG3 expression in CK- cells had 9.1 months of PFS compared to 3.1 months of PFS in patients with low LAG3 expression in CK- cells (p=0.10). In addition, patients with high LAG3 in CK- cells had longer overall survival(OS) compared to those with low LAG3 expression in CK- cells (median OS of high vs. low LAG3 expression [months]: not reached, 15.7, p=0.05). Conclusion LAG3 expression was associated with PFS in patients with mTNBC treated with ICI’s independent of PDL-1 expression. And the prognostic significance of LAG3 expression was different between CK+ cells and CK- cells. These findings need to be proved in large scale clinical trials. Citation Format: ji-Yeon Kim, Jeehyun Kim, Hae Hyun Jung, eun Yoon Cho, Yeon Hee Park, Jin Seok Ahn, Kyoung-Mee Kim, Young-Hyuck Im. Prognostic impact of lymphocyte-Activation Gene-3 (LAG-3) expression in triple negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-20-10.

Abstract P4-01-15: Preliminary results from a phase 2 study of praluzatamab ravtansine (CX-2009) in patients with advanced breast cancer (ABC)

Abstract Background: CD166 is broadly expressed in normal epithelium and overexpressed in many types of malignancies, including breast cancer. Probody® therapeutic candidates are masked antibodies, conditionally activated by tumor-associated proteases, which restricts their activity to the tumor microenvironment and minimizes ‘off-tumor’ toxicity. CX-2009 is a conditionally activated humanized anti-CD166 monoclonal antibody conjugated to DM4 that showed clinical activity in ABC patients in a phase 1 study (Boni et al. Clin Cancer Res. 2022). This phase 2 study (NCT04596150) evaluates CX-2009 as monotherapy in patients with advanced HR+/HER2− BC (Arm A) and TNBC (Arm B), and in combination with pacmilimab (a conditionally activated PD-L1) in TNBC (Arm C). Methods: Key eligibility criteria for all cohorts include: ECOG 0-1, acceptable end-organ function, measurable disease, willingness to receive ocular prophylaxis for DM-4 related toxicity, and available tumor tissue for CD166 evaluation. Eligibility criteria for HR+ BC include: 2-4 prior regimens (excluding single-agent hormonal therapy with up to 2 prior cytotoxic regimens) and a prior CDK 4/6 inhibitor in the metastatic setting; eligibility criteria for TNBC include CD166 by IHC >1% by central assessment, 1-3 prior regimens in the metastatic setting and prior taxane. All patients initially received 7 mg/kg Q3W; the protocol was subsequently amended to enroll patients at 6 mg/kg Q3W. The primary endpoint was overall response rate (ORR) using RECIST v1.1 assessed by central review. Other key endpoints include ORR by investigator assessment, clinical benefit rate at 24 weeks (CBR24; defined as any response, confirmed or unconfirmed, or SD for 24 weeks), duration of response, and progression-free survival by investigator. Archival tumor specimens and blood samples were collected for correlative research including genomic analyses. Results: As of 13 May 2022, 60 patients were enrolled in Arm A (all patients started at 7 mg/kg); 52 were evaluable for efficacy by investigator. Median duration of follow-up was 29.1 weeks (range: 3.6-60.7). Median age was 60.5 years (36, 83); pts received a median of 3.5 (1, 6) prior treatments for ABC. CD166 H-Score > 200 was reported in 53.3% of patients. Arm A met the primary efficacy endpoint with a confirmed ORR by central radiology of 14.9% (n=47); by investigator, ORR was similar at 15.4% (n=52); an additional 9 patients (17.3%) had an unconfirmed response. CBR24 was 40.4%; using only confirmed responses, CBR24 was 23.1%. Median PFS was 11.4 weeks (95% CI 9.0, 13.9). Common treatment-related all-grade adverse events (TRAEs) included blurred vision (42%), nausea (35%), fatigue (35%), diarrhea (25%), peripheral neuropathy (27%), infusion-related reaction (23%) and decreased appetite (20%). Grade ≥3 ocular and neuropathic TRAEs were 15% and 10%, respectively. AEs resulting in treatment discontinuation (AEDC) were 25%. For Arm B and C, 55 and 10 patients were enrolled (the majority received a starting dose of 6 mg/kg). For Arm B, the futility boundary was crossed (ORR < 10%). Grade ≥3 ocular and neuropathic TRAEs and AEDC at 7 mg/kg in Arm B were similar to Arm A (11%, 11% and 21% respectively); whereas at 6 mg/kg, they were reduced at 3%, 0% and 0%, respectively. Biomarker data and correlation with outcomes will be presented. Conclusions: Praluzatamab ravtansine demonstrated single-agent activity in unselected heavily pretreated patients with HR+/HER2- ABC. Time to event analyses, such as PFS, were confounded by higher-than-expected toxicity at a starting dose of 7 mg/kg. The toxicity profile was generally consistent with a DM4 payload. The lower dose of 6 mg/kg appears to be better tolerated. Additional clinical studies in HR+ABC, incorporating a starting dose of 6 mg/kg and potentially including a biomarker strategy, are warranted. Citation Format: Kathy Miller, Sara Tolaney, Leisha A. Emens, Sung-Bae Kim, Erika Hamilton, Cristina Saura, Lucia Sanz, Valentina Boni, Filipa Lynce, Juan Miguel Cejalvo, Jennifer Crozier, Shirley Wang, Hirdesh Uppal, Alison L. Hannah, Sara Hurvitz. Preliminary results from a phase 2 study of praluzatamab ravtansine (CX-2009) in patients with advanced breast cancer (ABC) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-01-15.

Abstract PD18-02: Adjuvant Paclitaxel and Trastuzumab Trial (APT) for Node-Negative, Human Epidermal Growth Factor Receptor 2–Positive (HER2+) Breast Cancer: final 10-year analysis

Abstract Background: The APT trial evaluated the activity of adjuvant paclitaxel and trastuzumab (TH) among patients with small, node negative HER2+ breast cancer. This regimen showed a 7-year invasive disease-free survival (iDFS) of 93%, a recurrence-free interval (RFI) of 97.5% with only four (1.0%) distant recurrences, and a 7-year overall survival (OS) of 95%. In this end-of-study analysis, we report the survival outcomes at 10 years and assess the role of HER2DX testing in predicting long-term outcomes with adjuvant TH. Methods: APT was a single-arm multicenter investigator-initiated phase II study in which patients with HER2+ breast cancer with tumors ≤3 cm and negative nodes (one single micrometastatic node allowed) received IV weekly paclitaxel (80 mg/m2) with IV weekly trastuzumab for 12 weeks, followed by IV trastuzumab for 9 months. The primary endpoint was 3-year iDFS. Here we report 10-year iDFS, RFI, breast cancer–specific survival (BCSS) and OS. In an exploratory analysis, the risk of recurrence was evaluated with the HER2DX genomic assay. Results: A total of 410 patients were enrolled from October 2007 to September 2010, of which 406 started the study treatment and were included in the intent to treat analysis. Median age at enrollment was 55 years (range, 24 to 85 years), and most patients (67%) had hormone receptor (HR)-positive disease. Fifty percent of patients had tumors 1.0 cm or smaller and only 9% of patients had tumors between 2 cm to 3 cm. Mean tumor size was 1.1 cm. After a median follow-up of 10.2 years (122 months), 36 iDFS events were observed, consistent with a 10-year iDFS of 89.7% (95% CI, 86.3%-93.1%). Ten-year iDFS was 90.2% (95% CI, 86.3%-94.3%) and 88.5% (95% CI, 82.4%-95.1%) for patients with HR-positive and HR-negative tumors at baseline, respectively. 10-year RFI was 96.8% (95% CI, 95.0%-98.7%), 10-year OS was 94.2% (95% CI, 91.6%-96.8%) and 10-year BCSS was 99.1% (95% CI, 98.1%-100.0%). Of the iDFS events observed in the trial, 6 were non-breast cancer related deaths and 9 were contralateral tumors, all but one locally found to be HER2-negative upon biopsy (Table 1). Among patients experiencing an iDFS event, 7 patients (1.7%) had distant recurrences, including 1 with a T2 tumor, 3 with a T1c tumor and 3 with a T1b tumor. At baseline, 6 of them had HR-positive disease, 1 had HR-negative disease, and 6 had high-grade disease. Upon biopsy of metastatic lesions, 5 of the 7 distant recurrences were locally found to be HER2+, 1 was HER2-negative and 1 had unknown HER2 status. HER2DX testing was conducted on available baseline archival tumor tissue and analyses of patients’ survival outcomes based on the HER2DX score will be presented. Conclusion: After 10 years of follow-up, adjuvant TH confirmed excellent long-term outcomes for small, node-negative HER2+ breast cancer, with a 10-year RFI of 96.8% and a 10-year BCSS of 99.1%. Table 1: iDFS events with adjuvant paclitaxel plus trastuzumab after 10.2 years of follow up Citation Format: Sara Tolaney, Paolo Tarantino, Noah Graham, Nabihah Tayob, Chau T Dang, Denise Yardley, Beverly Moy, Paul K. Marcom, Kathy S. Albain, Hope Rugo, Matthew Ellis, Iuliana Shapira, Antonio C. Wolff, Lisa Carey, Romualdo Barroso-Sousa, Michelle K. DeMeo, Molly K. DiLullo, Ann Partridge, Adrienne Waks, Clifford Hudis, Ian Krop, Harold Burstein, Aleix Prat, Eric Winer. Adjuvant Paclitaxel and Trastuzumab Trial (APT) for Node-Negative, Human Epidermal Growth Factor Receptor 2–Positive (HER2+) Breast Cancer: final 10-year analysis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD18-02.