ESTRO 2023 - Abstract Book

S817

Monday 15 May 2023

ESTRO 2023

comparison to the CRT alone group, e. g. median decrease of SUVmax –70.0% vs. –24.8%, respectively (p = 0.009). On the contrary, the spleen uptake increased after durvalumab initiation while it dropped in the group undergoing CRT alone (median +12.5% vs. –4.4%, p = 0.029). This was not the case for bone marrow uptake (+6.0% vs. –3.0, p = 0.353). The median follow up time of the overall group was 28 months. Few events (progression/death) were noted in patients undergoing additional durvalumab treatment and the progression-free survival was significantly longer in those patients (median 19 vs. 6 months, p = 0.008). PET/CT findings suggestive of an irAE (e.g. a sarcoid-like reaction) were present more often in patients undergoing durvalumab treatment compared to patients undergoing CRT alone (12/16 vs. 8/27 patients, p = 0.005). Conclusion Here, we present first preliminary data on the influence of durvalumab on 18F-FDG PET/CT findings in patients with unresectable stage III NSCLC undergoing chemoradiotherapy. Initiation of durvalumab consolidation after CRT leads to diverging metabolic patterns at tumor sites, but also alters splenic metabolism and leads to a significantly higher incidence of findings suggestive of irAE. PD-0970 Biodistribution Data of ImmunoPET: A Phase 0/1 Study Characterising PD-L1 with 89Zr- Durvalumab F. Hegi-Johnson 1 , S. Rudd 2 , P. Roselt 3 , C. Wichmann 4 , J. Callahan 5 , T. Akhurst 3 , P. Jackson 3 , R. Hicks 6 , A. Scott 7 , P. Donnelly 2 , T. John 8 , G. Hanna 9 , M. MacManus 9 1 Peter MacCallum Cancer Institute, Department of Radiation Oncology, Melbourne, Australia; 2 University of Melbourne, School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, Melbourne, Australia; 3 Peter MacCallum Cancer Centre, Department of Cancer Imaging, Melbourne, Australia; 4 La Trobe University, Olivia Newton-John Cancer Research Institute, and School of Cancer Medicine, Melbourne, Australia; 5 Peter MacCallum Cancer Institute, Department of Cancer Imaging, Melbourne, Australia; 6 St Vincent’s Medical School, University of Melbourne, Department of Medicine, Melbourne, Australia; 7 La Trobe University, Melbourne Australia, Olivia Newton-John Cancer Research Institute, and School of Cancer Medicine , Melbourne, Australia; 8 Peter MacCallum Cancer Centre, Department of Medical Oncology, Melbourne, Australia; 9 Peter MacCallum Cancer Centre, Department of Radiation Oncology, Melbourne, Australia

Purpose or Objective Introduction

ImmunoPET is a multicentre, single arm, phase 0-1 study that investigates the use of 89Zr-durvalumab PET/CT to interrogate the expression of PD-L1 in patients with NSCLC, in preparation for large clinical trials. We present the initial biodistribution data, which has been used to establish the safety and scan timepoints for a multicentre study in Stage III NSCLC patients.

Materials and Methods Methods

The Phase 0 study recruited 5 PD-L1+ patients with metastatic NSCLC and PD-L1 expression >25%. Patients received 60MBq/70kg 89Zr-durvalumab up to a maximum of 74 MBq, with scan acquisition at day 0, 1, 3 or 5 ± 1 day. Baseline FDG PET/CT was also performed 7 days prior to injection of 89Zr-durvalumab. Data on 1) Percentage of injected 89Zr durvalumab uptake found in organs of interest (%ID) 2) Absorbed organ uptake ( µ Sv/MBq of administered 89Zr-durvalumab) and 3) Whole-body dose expressed as mSv/100MBq of administered dose from our initial 5 patients are presented here.

Results Results

5 patients have been recruited to the Phase 0 study, with no significant toxicity observed after tracer injection. 89Zr durvalumab uptake increases from Day 0 to 5 post-injection in accordance with the long half-life of durvalumab (Figure 1). Data No significant toxicity was observed after tracer injection. However, 1 patient had a transient infusion reaction, developing tachypnoea that resolved within 1 hour after dexamethasone and anthistamines Biodistribution Data Normal biodistribution was characterized at 5 days by high levels of whole-body retention (mean 84%), low kidney dose 0.82 ±0.22 and 0.70 ±0.26 (Mean ± SD) %ID for right and left kidney respectively, and rapidly diminishing circulation in blood pool from Day 1 19.79 ± 3.5 (mean±SD) Suvmax to 8.31± 2.21 SUVmax at Day 5. A small diminishment in bone uptake from 10.97±1.21 to 9.60±1.60 (mean± SD) %ID was also observed over 5 days. Spleen uptake as measured by % ID increased slightly between rising from 2.22±0.27 (mean ± SD) on Day 1 to 2.94 ± 0.78 on Day 5. See Figure 2 for changes in SUVmax from Day 1 to 5. Safety