Functional Precision Medicine Vs Genomics Vs Clinical Experience: Feasibility Results from the Multicentric, Prospective, Randomized Controlled Exalt-2 Trial

Background

Aggressive hematological malignancies have a dismal prognosis in the relapsed/refractory setting representing an unmet medical need. Despite the advance of numerous novel therapeutics to clinical routine, treatment selection at advanced disease stages typically is challenging because of chemoresistance, cumulative toxicity, patient-specific factors, and a lack of evidence-based protocols in heavily pretreated patients. Precision medicine approaches promise to extend the number of candidate drugs beyond the standard of care, ultimately providing a treatment rationale in situations where evidence-based treatment options are scarce. We have previously shown that single-cell functional precision medicine (scFPM) is clinically feasible and efficacious in patients with aggressive hematological cancers who exceeded all standard therapy lines (Snijder et al. Lancet Haematology 2017, Kornauth et al, Cancer Discovery 2022). Inspired by this proof of concept, we launched a multicentric, prospective, randomized controlled trial to assess if genetic, or functional precision medicine-guided therapy may improve patient outcomes compared to best clinical experience-guided therapy (NCT04470947).

Methods

EXALT-2 is a multicentric, prospective, randomized controlled trial in five academic hospitals in Austria (Vienna, Graz, Innsbruck, Linz, and Salzburg). The study aims to enroll 150 patients with aggressive hematological malignancies in a relapsed/refractory setting with an overall good performance status (ECOG ≤ 1). After inclusion, a real-time tumor-containing biopsy is obtained to confirm relapse and collect viable tumor samples from each patient. Tumor cells are subjected to single-cell functional precision medicine (scFPM) and comprehensive genomic profiling (CGP) assays. Importantly, scFPM testing comprises flow cytometry- and/or imaging-based high-throughput drug screening.

Depending on the randomization arm, therapy is suggested by the multicentric, multidisciplinary EXALT-2 tumor board, which consists of at least 2 hematology specialists, a pathologist, a molecular biologist, and a pharmacist. The EXALT-2 board gives a treatment recommendation either based on i) scFPM or ii) CGP results, or iii) without any precision medicine support (Physicians’ Choice, PC). If precision medicine assays fail or do not yield a treatment recommendation, a cross-over between study arms is allowed. An overview of the study design is shown in Figure 1A.

Results

Feasibility results are available for the first 55 included patients. Of these, 54 patients (98%) underwent real-time biopsy and were randomized with an equal distribution across study arms. 42 patients (76%) received a therapy suggestion from the EXALT-2 tumor board. The majority of these patients suffered from aggressive lymphoma. Finally, 39 patients (71% of the total, 92% of patients with a board recommendation) received treatment. 10 patients were classified as early drop-outs due to death or progression within the first 28 days of board-recommended therapy according to the study protocol. 29 patients (53% of total, 69% of patients with a board recommendation) continued on study and are available for further evaluation.

Precision medicine assays were technically feasible in most instances (flow cytometry-based scFPM: 80% of tests; microscopy-based scFPM: 52% of tests; CGP: 86% of tests) and identified actionable hits in 100%, 100%, and 78%, respectively. The median time to report was shorter for scFPM than CGP testing (7 vs. 19 days, p<0.0001; Figure 1B). CGP identified a median of 1 (0-5) druggable genetic targets. In 60% of the patients (12 out of 20) with complete work-up, we observed a substantial overlap between genetic and functional (within the top 10 drug hits) results.

Conclusions

Our results provide further evidence that either genetic-based or functional precision medicine can be efficiently and safely implemented in clinical routine. scFPM and CGP aid to identify a rationale for innovative treatment options in a heavily pretreated cohort. Treatment recommendations can be translated to clinical application in the majority of these patients.