Hecht, J Randolph

Objective Identifying eligible patients for precision oncology clinical trials is challenging, particularly for rare molecular subpopulations. To address this challenge, A2 Biotherapeutics developed BASECAMP-1 ( NCT04981119 ), a non-interventional master screening study to identify patients eligible for interventional studies of logic-gated Tmod chimeric antigen receptor T-cell therapies. Eligible patients for these interventional trials have an advanced solid malignancy and are germline human leucocyte antigen (HLA)-A*02 heterozygous, with tumour-associated HLA-A loss of heterozygosity (LOH). HLA-A LOH occurs in ~16% of advanced solid malignancies; therefore, an efficient screening strategy is required. This report describes BASECAMP-1; compares the efficiency of two screening methods; and discusses the broader advantages of BASECAMP-1 beyond efficient enrolment. Methods and analysis Patients are identified for BASECAMP-1 using two approaches. In the traditional approach, common for clinical trials, investigators consent and screen all patients who might be good candidates for cell therapy trials, with no prior knowledge of patient HLA-A type or LOH status. To further optimise our approach, we co-developed with Tempus AI (Tempus) the bioinformatic programme Aware, which identifies potentially eligible patients with tumour-associated HLA-A*02 LOH within a clinico-genomic database that includes linked genomic and transcriptomic sequencing and clinical data collected during routine care. Results Over 42 months of using a traditional approach to identify eligible patients, 1918 patients at 13 study sites were consented and screened for BASECAMP-1; of these, 30 patients with tumour-associated HLA-A*02 LOH were enrolled (~0.7 participants per month). Over the last 30 months of that same period, Tempus Aware screening was implemented and 55 patients with tumour-associated HLA-A*02 LOH were enrolled (~1.8 participants per month). The bioinformatic approach identified more patients than the traditional approach and used sequencing results produced as part of the standard clinical tumour sequencing workflow, reducing resource use and study staff burden. Additional advantages of using a screening study, such as BASECAMP-1, include manufacturing efficiencies and collection of a large dataset of molecular and clinical parameters that can be used to supplement trial analyses. Conclusions The BASECAMP-1 study demonstrates a clinico-genomic screening approach can more efficiently identify patients for precision oncology trials. Furthermore, precision oncology can be enhanced through collaborative data-sharing. Trial registration number NCT04981119 .

Abstract Background: Despite the success treating hematologic malignancies, chimeric antigen receptor T-cell (CAR T) therapies face challenges in breast cancer and other solid tumors due to lack of targets that distinguish tumor from normal cells. Epithelial growth factor receptor (EGFR) plays a critical role in oncogenesis across several cancers and is often upregulated [1]. While monoclonal antibodies targeting EGFR have demonstrated efficacy, these approaches are often limited by on-target, off-tumor toxicities, such as skin and gastrointestinal toxicity, which constrains dose escalation and efficacy [2]. A2B395 is an allogeneic, logic-gated, EGFR-targeted, TmodTM CAR T therapy designed to address these limitations and provide a convenient and consistent off-the-shelf option. This therapy incorporates 2 CARs: an activator targeting EGFR and a blocker targeting human leukocyte antigen (HLA)-A*02. The activator recognizes EGFR on both tumor and normal cells, whereas the blocker inhibits CAR T activity against normal cells (with preserved HLA expression) while allowing activation against tumor cells (with HLA-A*02 loss of heterozygosity [LOH]). This approach is designed to avoid on-target, off-tumor toxicity, a significant limitation to CAR T treatment of solid tumors [3]. To address potential graft-vs-host response, a short-hairpin RNA expression module targeting beta-2 microglobulin is included in the Tmod construct, which significantly reduces major histocompatibility complex class I levels and subsequent host immune response [4]. Importantly, the Tmod system is modular and adaptable to multiple targets. Initial data on autologous Tmod CAR T therapy suggest reduced off-tumor toxicity and encouraging clinical efficacy [5]. A2B395 represents a novel approach for targeting EGFR-expressing solid tumors with HLA-A*02 loss of heterozygosity. Methods: DENALI-1 is a phase 1/2, open-label, nonrandomized study evaluating the safety and efficacy of A2B395 in adults. Patients are enrolled through BASECAMP-1 (NCT04981119), a master prescreening study that identifies patients with HLA loss of heterozygosity at any time in the course of their disease via next-generation sequencing. Key inclusion criteria include histologically confirmed recurrent, unresectable, locally advanced, or metastatic cancers associated with EGFR expression, including triple-negative breast, colorectal, non-small cell lung, squamous cell head and neck, and renal cell cancers. Patients must have received ≥1 line of prior therapy, such as a checkpoint inhibitor, molecular targeted therapy, or chemotherapy. The primary objective of the phase 1 portion is to evaluate safety, tolerability, and the recommended phase 2 dose (RP2D) using a Bayesian optimal interval design for dose escalation. The dose-expansion phase will confirm the RP2D and collect and analyze biomarker data. The Phase 2 portion will assess overall response rate per RECIST v1.1. As of 03 July 2025, the first patient dosed with A2B395, who has breast cancer, completed the 28-day safety review period. Dose-escalation is ongoing. Citation Format: J. M. Specht, S. R. Punekar, M. Ulrickson, D. J. Wong, J. R. Hecht, M. Maus, P. M. Grierson, J. B. Sunwoo, J. R. Molina, D. G. Maloney, K. Spencer, H. E. Fuentes Bayne, M. Davila, S. P. Patel, B. Creelan, D. B. Zhen, J. Niu, D. C. Prasad, R. L. Marar, N. A. Bagegni, G. Palluconi, J. Lee, A. Mardiros, W. Bretzlaff, W. J. Langeberg, J. S. Welch, E. Ng, W. Y. Go, K. Kirtane, R. A. Shatsky. Denali-1: a seamless phase 1/2 study of A2B395, a logic-gated, allogeneic, Tmod chimeric antigen receptor T-cell (CAR T) therapy, in patients with triple-negative breast cancer and other EGFR-expressing solid tumors with HLA-A*02 loss of heterozygosity (LOH) [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS5-08-03.