Liu, Suyu

PURPOSE We tested the hypothesis that adding metastasis-directed therapy (MDT) to standard-of-care (SOC) systemic therapy improves progression-free survival (PFS) among patients with oligometastatic disease. METHODS EXTEND was a multicenter randomized phase II trial. Patients with 1-5 metastases were randomly assigned to MDT + SOC versus SOC in one of the six baskets (breast, pancreas, kidney, two prostate baskets, and an other basket) with basket-specific stratification and powering. PFS, the primary end point, was prespecified in the per-protocol set within each basket, across all baskets, and across all baskets excluding the prostate baskets. Exploratory end points included circulating tumor DNA (ctDNA) and immune profiling. RESULTS From 2018 through 2023, 521 patients were screened, 350 were randomly assigned, and 334 were analyzed per protocol (MDT + SOC, n = 166; SOC, n = 168). Radiotherapy was used as MDT for 98% of metastases (370/379). Overall, after a median follow-up of 53 months, PFS was improved with MDT + SOC (hazard ratio [HR], 0.54 [95% CI, 0.41 to 0.72], P < .001). Similarly, PFS was improved when excluding the prostate baskets (HR, 0.60 [95% CI, 0.40 to 0.89]). Within each basket, PFS superiority was identified for the pancreas, prostate, and other baskets, whereas the breast and kidney baskets were inconclusive. At enrollment, detectable ctDNA correlated with shorter PFS and survival; by contrast, ctDNA clearance 3 months postenrollment correlated with improved survival. MDT + SOC-induced systemic immune activation was most pronounced among baskets demonstrating PFS superiority. CONCLUSION The phase II EXTEND trial supports the addition of MDT to SOC for oligometastatic disease. Histology-specific efficacy signals were identified for phase III testing. Translational insights suggest the potential for optimizing the definition of oligometastasis using ctDNA and point to systemic immune responses as a possible mechanism of benefit from MDT.

Abstract Purpose: The Pancreatic Cancer Detection Consortium (PCDC) performed a blinded Early Detection Research Network–defined phase II biomarker bakeoff study of blood-based biomarker panels. The aims were to evaluate panel performance, to compare the panels’ performance with that of cancer antigen 19-9 (CA19-9) alone, and to evaluate the performance of new combinations of the individual biomarkers. Experimental Design: Ten biomarkers representing eight biomarker panels and CA19-9 were evaluated using plasma, serum, and germline DNA from 140 stage I to IV pancreatic ductal adenocarcinoma (PDAC) cases and 140 controls from three tertiary care institutions, with controls frequency matched to cases on age and sex. LASSO regression was employed to explore new biomarker combinations. The primary metric was area under the receiver operating characteristic curve (AUC). Results: The study population was 51% female, with median age 67.3 (minimum: 45, maximum: 90) years. Biomarker panel AUCs ranged from 89.9 to 96.3; the AUC for serum CA19-9 alone was 91.7 [95% confidence interval (CI), 87.8–95.6]. Two panels had significantly higher AUCs than serum CA19-9 alone, the CA19-9/FUT2/3 panel (AUC = 96.3, P = 0.002), and the tissue factor pathway inhibitor/tenascin C (TFPI/TNC-FNIII-C) panel (AUC = 95, P = 0.01). Exploratory models to recombine biomarkers retained all but two biomarkers [optimism-corrected AUC = 96.4 (94–98.9)]. Conclusions: The CA19-9/FUT2/3 panel was the best performing panel in this biomarker bakeoff. Its evaluation in larger studies is warranted. Biomarker bakeoffs are an effective strategy for comparing the performance of promising biomarkers for pancreatic cancer early detection, and the PCDC is well poised to conduct such studies. Recommendations for performing such studies are provided.