DYNAMIC-III Trial

[Slide 1] GASTROINTESTINAL CANCER-COLORECTAL AND ANAL 3503 Oral Abstract Session ctDNA-guided adjuvant chemotherapy escalation in stage III colon cancer: Primary analysis of the ctDNA-positive cohort from the randomized AGITG dynamic-III trial (intergroup study of AGITG and CCTG). Jeanne Tie, Yuxuan Wang, Jonathan M. Loree, Joshua D. Cohen, David Espinosa, Rachel Wong, Timothy Jay Price, Niall C. Tebbutt, Margaret Lee, Matthew E. Burge, Samuel John Harris, Belinda Lee, James F. Lynam, Christopher J. O'Callaghan, Daniel Adam Breadner, Chetan Bettegowda, Nickolas Papadopoulos, Kenneth W. Kinzler, Bert Vogelstein, Peter Gibbs; Department of Medical Oncology, Peter MacCallum Cancer Centre and Personalised Oncology Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia; Ludwig Center for Cancer Genetics and Therapeutics, Johns Hopkins University School of Medicine, Baltimore, MD; BCCA Vancouver Cancer Centre, University of British Columbia, Vancouver, BC, Canada; NHMRC Clinical Trials Centre, Sydney, Australia; Eastern Health, Box Hill, Australia; Queen Elizabeth Hospital, University of Adelaide, Woodville, SA, Australia; Warringal Private Hospital, Melbourne, Australia; Eastern Health, Western Health, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia; Royal Brisbane and Women's Hospital, Herston, QLD, Australia; Bendigo Cancer Centre, Bendigo Health, Bendigo, VIC, Australia; Northern Health & Peter MacCallum Cancer Centre & Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia; Newcastle Private Hospital, Newcastle, Australia; Canadian Cancer Trials Group, Queen's University, Kingston, ON, Canada; Verspeeten Family Cancer Centre at the Schulich School of Medicine and Dentistry, London, ON, Canada; Johns Hopkins University School of Medicine, Baltimore, MD; Walter & Eliza Hall Institute of Medical Research and Western Health, Melbourne, Australia Background: Despite adjuvant chemotherapy (ACT) a proportion of patients (pts) with stage III colon cancer (CC) will recur. Most at risk are those with detectable ctDNA, whereas those with undetectable ctDNA have a reduced recurrence risk. The DYNAMIC-III study explored the impact of ACT de-escalation or escalation as informed by post-surgery ctDNA results. Here, we report the primary analysis on the impact of treatment escalation in ctDNA-positive pts. Outcome data for treatment de-escalation in ctDNA-negative pts is immature. Methods: DYNAMIC-III is a multi-center, randomized, phase II/III trial. Eligible pts had resected stage III CC and were fit for ACT. Pts were randomly assigned 1:1 to ctDNA-informed or standard of care (SOC) management. Clinicians nominated the selected SOC ACT regimen prior to ran- domization. For ctDNA-informed management, a ctDNA-positive result at 5-6 weeks after surgery with a tumor-informed assay prompted an escalation ACT strategy (from single agent fluoropyrimidine [FP] to oxaliplatin-based doublet, from 3 months doublet to 6 months doublet or FOLFOXIRI [clinician choice], or from 6 months doublet to FOLFOXIRI). The primary efficacy endpoint for the ctDNA-positive cohort was 2-year RFS. The target sample size of 250 provided 80% power with 90% confidence to confirm superiority of ctDNA-informed treat- ment escalation compared to SOC with a HR of 0.746. Results: Of 961 eligible pts randomized between Oct 2017 and Apr 2023, 259 (27%) were ctDNA-positive. Of these, 113 (44%) had clinical low risk disease (non-N2 + non-T4). Median follow-up was 42.2 months (range 0.78 - 63.0). 115 (89%) of 129 ctDNA-informed pts received ACT escalation, with 65 (56%) receiving FOLFOXIRI. Of 130 SOC pts, 14 (11%) and 112 (86%) received single agent FP and oxaliplatin doublet, respectively. 2-year RFS for ctDNA-informed treatment escalation was 52% (90% CI: 44 - 59%) vs 61% (90% CI: 54 68%) for SOC (HR 1.11, 90% CI: 0.83 1.48; P = 0.6). The 3-year RFS for ctDNA-positive pts receiving FOLFOXIRI and FOLFOX/CAPOX was similar (47% vs 51%, HR 1.09, 90% CI 0.78 to 1.53; P = 0.7). In a pre-specified correlative analysis of all ctDNA positive pts, recurrence risk increased with ctDNA burden, with 3-year RFS of 78%, 63%, 36% and 22% for tumor-derived mutant molecules/mL quartiles < 0.06, 0.06 - 0.17, 0.18 - 1.31, and > 1.31, respectively (P < 0.01). Treatment-related hospitalisation was similar for escalated and SOC pts (OR 1.21, P = 0.58). Analysis of post-ACT ctDNA is underway. Conclusions: In this first randomised study of ctDNA-informed management in stage III CC, we confirm the prognostic significance of detectable ctDNA, with the novel finding of recurrence risk increasing markedly with ctDNA burden. Treatment escalation, including to FOLFOXIRI, did not improve RFS. Future studies in ctDNA positive pts should explore other escalation strategies. Clinical trial infor- mation: ACTRN12617001566325. Research Sponsor: Marcus Foundation; NHMRC; U.S. National Institutes of Health.

[Slide 1] ctDNA-Guided Adjuvant Chemotherapy Escalation in Stage III Colon Cancer : statistical concerns No formal hypotheses HO and H1 as usually in non The NEW ENGLAND JOURNAL of MEDICINE comparative randomized phase II trials ORIGINAL ARTICLE Randomized non-comparative phase II but Oxaliplatin, Fluorouracil, and Leucovorin as Adjuvant Treatment for Colon Cancer comparisons are provided 10 0.9 FL plus examplation (237 events, 21 1%) How can we target a HR of 0.746 with only 250 pts? 0.0 case free Survival 0.7 FL (293 events 26 293 0.6 Underpowered : for the targeted HR of 0.746 a n.e. In MOSAIC 2200+ pts power of 37% was expected (???) for a 5% difference in 3-y DFS and an HR of 0.78 Conclusions are at most hypothesis generating 0 5 12 :$ 24 10 34 42 48 Months No. at Risk FLe oxaliplatin 1123 1086 1021 959 *** 663 395 FL 1123 1006 981 903 817 619 156 MOSAIC trials (NEJM 204) 2025 ASCO #ASCO25 PRI SENTED BY: Julien TAIEB, MD, PhD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLDGY ANNUAL MEETING Presentation is property of the author and ASCO Permission required for - contact permissions@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 2] ctDNA-Guided Adjuvant Chemotherapy Escalation in Stage III Colon Cancer :Main results Recurrence free survival Is it acceptable to do this comparison? 1.0 No randomization of CT regimen 0.8 Why FOLFOXIRI 3 to 6 M and not 6M ? FOLFOX/CAPOX 0.6 51% CAPOX and FOLFOX: high and low-risk patients FOLFOXIRI FOLFOXIRI high-risk patients only 0.4 47% 0.2 HR 1.09 (0.78, 1.53), P = 0.662 TDMM/mL, median (IQR) P FOLFOXIRI 0.28 (0.06, 1.78) 0.236 0.0 0 6 12 18 24 30 36 12 IS Doublet 0.15 (0.06, 0.97) Time from randomisation - Months FOLFOXIRI 65 64 62 57 51 ++ 36 32 30 19 23 22 20 19 1" 16 IS Doubles 169 16-4 156 144 134 120 103 96 76 67 60 53 47 45 40 35 33 Imbalance in baseline characteristics 2025 ASCO #ASCO25 PRESENTEDUARION TAIEB, MD, PhD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation # property of the author and ASCO Temasure required for - contact Causing KNOWLEDGE CONQUERS CANCER --- [Slide 3] ctDNA-Guided Adjuvant Chemotherapy Escalation in Stage III Colon Cancer :my conclusions Altogether DYNAMIC confirms that "when it goes bad it goes bad" Escalation in ctDNA positive patients is inefficient to improve RFS in DYNAMIC FOLFOXIRI and CAPOX/FOLFOX groups were not randomized and lets wait for the IROCAS-PRODIGE-GONO-CCTG study results next year (FOLFIRINOX vs FOLFOX in T4/N2 cc) High number attrition for ctDNA clearance makes results more hypothesis generating than conclusive 2025 ASCO #ASCO25 PRI SENTECULATION TAIEB, MD, PhD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation is property of the author and ASCO Permission required for revie, contact permissore@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 4] ctDNA-Guided Adjuvant Chemotherapy Escalation in Stage III Colon Cancer :my conclusions However these results, though not completely conclusive, suggest that: ctDNA clearance post treatment may be a potential new primary endpoint in future trials ACCENT-CIRCULATE working group for confirmatory pooled analyses We need more than chemotherapy intensification to improve outcome in stage III CC patients 20 years after the publication of MOSAIC PLATFORM TRIALS WITH NEW TREATMENT OPTION and NEW TREATMENT STRATEGIES New treatments (targeted agents, ADCs, ICIs) and New treatment strategies (neo-adjuvant, sequential or even both 2025 ASCO #ASCO25 TAIEB, MD. PhD ASCO AMERICA AN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation a property of the author and ASCO Permission required for - consect permissions@ass.org KNOWLEDGE CONQUERS CANCER

[Slide 1] Recurrence-Free Survival 1.0 Median 0.8 Total RFS 2-year RFS 3-year RFS Events (90% CI) (90% CI) (mths) 61% 52% 48% 0.6 ctDNA 129 66 29.24 52% (44, 59) (40, 55) 61% 52% 52% SoC 130 62 36.80 0.4 48% (54,68) (44, 60) HR (90% CI): 1.11 (0.83, 1.48), P = 0.57 0.2 — Standard management Median follow-up 42.2 months (0.78 - 63.0) - ctDNA-informed escalation 00 0 6 12 18 24 30 36 42 48 Time from randomisation - - Months ctDNA-Informed 129 123 118 109 101 90 76 68 55 52 42 38 33 32 28 26 25 Standard 130 126 120 111 101 91 79 74 63 54 50 44 40 37 34 30 28 Data cut-off: 14 Nov 2024 2025 ASCO #ASCO25 PRE SENTED BY: Jeanne Tie, MBChB FRACP MD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation is property of the author and ASCO Permission required for reuse, contact permissions@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 2] DYNAMIC-III Study Design Randomized Phase 11/111 (ACTRN12617001566325) Tumor-Informed Stage III ctDNA Analysis ctDNA-Informed Management Pre-Planned SoC Escalation Colon Cancer (SaferSeqS¹ targeted CRC panel) ctDNA-Negative De-escalate R0 resection No chemotherapy 5FU/Cape ECOG 0 - 2 ctDNA-Positive Escalate 5FU/Cape 6M Oxaliplatin doublet Fit for at least a fluoropyrimidine (FP) 1 cycle of pre-planned chemotherapy allowed R 3M Oxaliplatin doublet 6M Doublet prior to ctDNA-informed regimen Staging CT within 12 W5-6 1:1 or ≥ 3M FOLFOXIRI weeks Provision of 6M Oxaliplatin doublet ≥ 3M Standard Management adequate tumor FOLFOXIRI Clinicians tissue < 6 weeks nominate Treatment per clinician's choice post-operation SoC Chemo (blinded to ctDNA result) No synchronous colorectal cancer Stratified by clinical risk (low VS high) and sites Primary Analysis of ctDNA-Positive Cohort: Endpoints to be Presented Secondary: safety, end-of-treatment (EoT) ctDNA clearance Primary: 2 years RFS Exploratory: post-operative ctDNA levels 1. Cohen, J.D. et al. Nat Biotechnol 39, 1220-1227 (2021) 2025 ASCO #ASCO25 PRE SENTED BY: Jeanne Tie, MBChB FRACP MD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation is property of the author and ASCO Permission required for reuse, contact permissions@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 3] Post-Op ctDNA Molecular Burden and RFS RFS: ctDNA Burden by Quartiles TDMM / mL RFS HR (90% CI) P ≥1.31 1 <.0001 1.0 0.18-1.31 0.65 (0.46, 0.93) 83% 0.06-0.17 0.26 (0.17, 0.39) 78% 0.8 TDMM <0.06 <0.06 0.17 (0.10, 0.27) 74% TDMM 0.06-0.17 0.6 63% 43% 0.4 36% TDMM 0.18-1.31 26% TDMM >1.31 0.2 22% 00 0 6 12 18 24 30 36 42 48 Time from randomisation - Months 1 64 56 52 43 36 29 21 19 14 14 11 10 9 8 8 7 6 2 64 62 58 51 42 36 30 28 21 19 15 14 11 11 11 8 6 3 67 67 66 64 63 57 51 47 41 36 32 27 25 24 23 23 23 4 64 64 62 62 61 59 53 48 42 37 34 31 28 26 20 18 18 TDMM = Tumor derived mutant molecule 2025 ASCO #ASCO25 PRE SENTED BY: Jeanne Tie, MBChB FRACP MD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation is property of the author and ASCO Permission required for reuse, contact permissions@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 4] Post-Hoc Analysis: FOLFOXIRI VS FOLFOX/CAPOX Recurrence free survival TDMM/mL, median (IQR) P FOLFOXIRI 0.28 (0.06, 1.78) 0.236 1.0 Doublet 0.15 (0.06, 0.97) 0.8 ctDNA Clearance Rate by Regimen FOLFOX/CAPOX ns 0.6 51% 100 FOLFOXIRI Clearance 0.4 47% 80 No Clearance 0.2 EoT ctDNA Status (%) 60 HR 1.09 (0.78, 1.53), P = 0.662 40 0.0 60% 62% 0 6 12 18 24 30 36 42 48 20 (31/52) (47/76) Pause Time from randomisation - Months POLPOXIRI 65 64 62 57 51 44 36 32 30 29 23 22 20 19 17 16 15 0 Doublet 169 164 156 144 134 120 103 96 76 67 60 53 47 45 40 35 33 FOLFOXIRI Doublet 2025 ASCO #ASCO25 PRE SENTED BY: Jeanne Tie, MBChB FRACP MD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation is property of the author and ASCO Permission required for reuse, contact permissions@asco.org KNOWLEDGE CONQUERS CANCER

[Slide 1] DYNAMIC-III Study Design Randomised Phase II/III (ACTRN12617001566325) Stage III ctDNA-Informed Management Colon Cancer ctDNA-Negative De-escalate R0 resection ctDNA-Positive Escalate ECOG 0-2 - Fit for at least a 1 cycle of pre-planned chemotherapy allowed prior to fluoropyrimidine (FP) R ctDNA-informed regimen Staging CT within 12 W5-6 1:1 weeks Provision of adequate Standard Management tumor tissue <6 weeks post-operation Treatment per clinician's choice No synchronous (blinded to ctDNA result) colorectal cancer Stratified by clinical risk (low VS high) and sites Jeanne Tie Content of this presentation is copyright and responsibility of the author Permission is required for re-use 1. Cohen, J.D. et al. Nat Biotechnol 39, 1220-1227 (2021) BERLIN 2025 ESMO congress --- [Slide 2] Recurrence-Free Survival Median follow-up 47 months (0.68 - 67.0) 100 88.1 Arm Total Events 90 Standard 3-year RFS (95% CI) 80 85.3 ctDNA 353 63 85.3% (81, 89) ctDNA-guided 70 Recurrence-free Survival (%) Standard 349 45 88.1% (84, 91) 60 50 40 Absolute Difference in 3-year RFS (95% CI) 30 20 Absolute difference -2.8% 10 (95% CI, -8.0% to 2.3%) -8.0% 0 0 12 24 36 48 60 Months from Randomization No. at Risk ctDNA-guided 353 333 303 214 124 51 -10.0 -7.5 -5.0 -2.5 0 2.5 Standard 349 336 310 223 143 46 Standard better ctDNA-guidance better Jeanne Tie Database lock July 29, 2025 Content of this presentation is copyright and responsibility of the author Permission is required for re-use BERLIN 2025 ESMO congress --- [Slide 3] RFS by Clinical Risk Clinical Low Risk (T1-3N1) Clinical High Risk (T4 and/or N2) 100 93.2 Standard 100 90 90 91.0 78.6 80 ctDNA-guided 80 Standard 70 70 Recurrence-free Survival (%) 60 40 30 Recurrence-free Survival (%) 72.8 60 ctDNA-guided 50 50 40 30 20 20 10 Absolute difference -2.2% (95% CI, -7,2% to 2.7%) 10 Absolute difference -5.8% (95% CI, -17.0% to 5.4%) 0 0 0 12 24 36 48 60 0 12 24 36 48 60 Time from Randomization (months) Time from Randomization (months) No. at Risk No. at Risk tDNA-guided 242 233 219 160 93 39 ctDNA-guided 111 100 84 54 31 12 Standard 227 222 209 152 95 32 Standard 122 114 101 71 48 14 Jeanne Tie Content of this presentation is copyright and responsibility of the author Permission is required for re-use BERLIN 2025 ESMO congress --- [Slide 4] ctDNA-Negative vs ctDNA-Positive: RFS 100 87 RFS by ctDNA Molecular Burden (Quartiles) 90 0 TDMM 77 80 0<TDMM<0.06 TDMM / mL RFS HR (90% CI) P 70 60 Recurrence-free Survival (%) 0.06-0.17 TDMM ≥1.31 1 <.0001 60 50 0.18-1.31 0.67 (0.47, 0.94) . . 40 37 0.18-1.31 TDMM 0.06-0.17 0.28 (0.19, 0.42) - 30 23 >1.31 TDMM >0 to <0.06 0.17 (0.10, 0.27) . 20 10 0 (ctDNA-negative) 0.10 (0.07, 0.13) . 0 TDMM = Tumour derived mutant molecule 0 12 24 36 48 60 e a C . S Γ Months from Randomization No. at Risk >1.31 TDMM 64 36 17 12 8 3 0.18-1.31 TDMM 64 42 25 16 10 3 0.06-0.17 TDMM 67 63 48 32 24 10 0<TDMM<0.06 64 61 52 34 22 6 0 TDMM 702 669 613 437 267 97 Jeanne Tie Content of this presentation is copyright and responsibility of the author. Permission is required for re-use BERLIN ESMO congress

[Slide 1] ctDNA-Guided Adjuvant Chemotherapy Escalation in Stage III Colon Cancer :Main results Recurrence free survival 1.0 Primary endpoint is not reached 0.8 61% 0.6 52% 52% 0.4 48% HR (90% CI): 1.11 (0.83, 1.48), P = 0.57 0.2 - Standard management - ctDNA-informed escalation 00 0 6 12 18 24 30 36 42 48 Time from randomisation - Months ctDNA Informed 129 123 118 109 101 90 76 68 55 52 42 38 33 32 28 26 25 Standard 130 126 120 111 101 91 79 74 63 54 50 44 40 37 34 30 28 2025 ASCO #ASCO25 PRESENTED BY: Julien TAIEB, MD. PhD ASCO AMERICAN SOCIETY OF CLINICAL ONCOLOGY ANNUAL MEETING Presentation . property of the author and ASCO Permission required for - contact permissions@asco.org KNOWLEDGE CONQUERS CANCER --- [Slide 2] Limitations CtDNA is an amazing tool - but it didn't make FOLFOX more effective Lead time bias Limitations of detection - By tumor site: peritoneum, lung, low tumor burden - Types of alterations: fusions and amplifications (e.g. 15-20% false negative rate for HER2 amplification) Technical Failure: May be as high as 15% in clinical practice Cost: Upfront cost with likely downstream cost-savings Patient anxiety