S782
Clinical - Lung
ESTRO 2026
Stockholm, Sweden. 4 Department of Oncology- Pathology, Karolinska Institutet, Stockholm, Sweden
overall survival (OS), time to treatment discontinuation (TTD), and time to new systemic therapy (TTNT) were assessed. Results: Twenty-one irradiation courses were delivered concurrently with amivantamab in 14 patients. Median age was 63 years (range, 36–76). Most patients were never-smokers (71%) and had ECOG 0–1 (79%). Molecular alterations included EGFR exon 19 deletion (64%), EGFR L858R (14%), EGFR exon 20 insertions (14%), and one MET exon 14 skipping mutation (7%); one patient also had MET amplification. Most patients (86%) had received prior systemic therapy. Radiotherapy indications were oligoprogression (29%) and palliation (71%); irradiated sites included the brain (19%), thorax (19%), lumbosacral spine (14%), adrenals (10%), and extremities (10%). The median planning target volume was 110 cc (IQR 48–292) and the median interval between amivantamab infusion and radiotherapy was 3 days. After a median follow-up of 8.0 months (IQR 4.0–9.1) for toxicity and 9.5 months (IQR 4.9–44.8) for oncologic outcomes, no grade ≥ 3 RT-related toxicities were observed. Thirteen grade 1 acute, six grade 2 acute (pneumonitis, cough, esophagitis, lymphopenia, fatigue, and nausea), and three grade 1 late toxicities were reported. The 6- and 12-month OS rates were 77% (95% CI 43–92%) and 50% (95% CI 15–78%), respectively. Among 11 patients continuing amivantamab after radiotherapy, median PFS, TTD, and TTNT were 4.5, 4.8, and 5.5 months, respectively. Palliative RT achieved symptom relief in 87% of irradiations (5 complete, 8 partial), while LC after RT for oligoprogressive disease was maintained in 80% of cases. Conclusion: Concurrent radiotherapy and amivantamab was well tolerated, with no grade ≥ 3 events observed. These early findings support the feasibility of combining RT with amivantamab in selected patients with EGFR- or MET-altered NSCLC and warrant further validation. Keywords: amivantamab, EGFR, concurrent, bispecific antibody Mini-Oral 2117 Real-world outcomes of prophylactic cranial irradiation in patients with limited disease small cell lung cancer in a Scandinavian patient cohort Sara Linde 1,2 , Ditte S Møller 1,2 , Hjørdis H Schmidt 1 , Azza A Khalil 1 , Karin Lindberg 3,4 , Lise S Mortensen 1 , Lone Hoffmann 1,2 , Marianne M Knap 1 , Luigi De Petris 3,4 , Asaf Dan 3,4 1 Department of Oncology, Aarhus University Hospital, Aarhus, Denmark. 2 Department of Clinical Medicine, Aarhus University, Aarhus, Denmark. 3 Thoracic Oncology Center, Karolinska University Hospital,
Purpose/Objective: Prophylactic cranial irradiation (PCI) is recommended in international guidelines for fit patients with limited disease small cell lung cancer (LD-SCLC) who respond to curative chemoradiotherapy. PCI treatment was established with a 1999 study finding a survival benefit of PCI over no PCI for these patients. At Karolinska University Hospital, Sweden, and Aarhus University Hospital, Denmark, PCI use declined after 2017, despite guidelines not changing. We therefore aimed to determine whether patients who received PCI after 2017 – commonly regarded as a selected group – truly differed from those not receiving PCI, and whether any real-world outcome advantage could be attributed to patient selection rather than to PCI itself. Material/Methods: Patients with LD-SCLC treated with a curative intent at the two institutions from January 1st, 2018, to December 31st, 2022, were reviewed. Patients were treated with chemoradiotherapy, with thoracic radiotherapy doses of either 45Gy (110 patients) or 60Gy (20 patients). In total 130 patients (34 Swedish and 96 Danish) were included. The cohort was divided into patients receiving PCI (PCI group, n=44) and patients who did not (noPCI group, n=86). The baseline characteristics, survival estimated by Kaplan-Meier, and cumulative incidence of symptomatic brain metastases were compared for the two groups. Results: In the cohort 34% received PCI (26.5% of the Swedish patients and 36.5% of the Danish patients). Patients in the PCI group were younger, median age was 64 years [46-77] compared to 71 years [44-86] for the noPCI group (p<0.01). No statistically significant difference was found in sex, disease stage, smoking status, performance status, diagnostic brain imaging, chemotherapy agent, chemotherapy regimen nor radiotherapy regimen, table 1. With a median follow- up of 49 months, the cohort had a median overall survival (mOS) of 28 months (95%CI 17-39). mOS was 25 months (95%CI 17-33) and 28 months (95%CI 12-44) in the PCI and noPCI groups respectively, with no statistical difference by log-rank test (p=0.95), figure 1. There were 32 events of symptomatic brain metastases (9 PCI group and 23 noPCI group), with no significant difference in cumulative incidence assessed by Gray’s test, with death as a competing risk (p=0.41). Conclusion: Only 34% of patients treated with a curative intent for LD-SCLC at the two institutions received PCI. The only difference between the two groups was age. No real- world outcome advantage was found for these patients treated after 2017, with no statistically significant difference in survival nor cumulative
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