Marinello, Arianna

Abstract Purpose: In RET-rearranged non–small cell lung cancer (NSCLC), treatment options after first-generation selective RET inhibitors (SRI) are limited, and the value of SRI retreatment remains unclear. This study evaluates outcomes of SRI retreatment. Experimental Design: This multicenter retrospective study included patients with advanced RET-rearranged NSCLC who received ≥2 SRI-based therapy lines. Of 411 SRI-treated patients, 41 (10%) underwent SRI retreatment. Outcomes included objective response rate (ORR), progression-free survival (PFS), 6-month PFS, time to treatment failure, adverse events (AE). Results: Among 41 patients, 14 (34%) discontinued the initial SRI because of toxicity and 27 (66%) because of progression. After discontinuation for toxicity, all switched to an alternate SRI, achieving an ORR of 67%, median PFS of 9.9 months, and 6-month PFS of 80.3%. AEs reoccurred in nine patients (64%), with grade ≥3 AEs in 3 (21%) who switched at full dose. Among patients who discontinued because of progression, SRI monotherapy (n = 13) achieved an ORR of 23%, median PFS of 7 months, and 6-month PFS of 61.5%. Benefit was observed in patients with brain-only or oligoprogressive disease or dose reduction on first SRI. Combination therapy (n = 14; targeted agents, n = 11; chemotherapy, n = 3) achieved an ORR of 39%, median PFS of 4 months, and 6-month PFS of 27.3%. Conclusions: Same-class SRI switch after toxicity is feasible and clinically active but warrants cautious, dose-adjusted switching to mitigate toxicities. The efficacy of SRI rechallenge after progression seems limited overall. However, selected patients, such as those with brain-only or oligoprogressive disease, may derive benefit.

8019 Background: Neoadjuvant and perioperative chemo-immunotherapy studies report 15%-20% of pts initiating NACT-I do not undergo surgical resection. Methods: Real-world data of pts who initiated NACT-I was collected retrospectively for January 1 st 2022 till September 30 th 2024. Pts and treatment details, reason for not undergoing resection (as assessed by the clinicians) and later treatments and outcomes were recorded. Total number of pts who initiated NACT-I in this period was identified from each center's records. Missing data was not imputed. Results: Data was collected from 10 centers in 4 countries (USA, Israel, Switzerland, France). Out of 330 pts that started NACT-I 43 pts (13%; range 4-33% in different centers) did not undergo surgical resection. Of these 43 pts, 34.9% became unresectable due to disease progression (PD). 20.9% in retrospect were non-resectable and did not regress as expected. 11.6% in retrospect were non-operable. 11.6% suffered toxicity and became unfit for surgery. 7% of pts refused surgery, 14% were not resected for other reasons (Table). Of the non-resected pts, 9.3% died prior to any second-line treatment. As a second line, 44.2% of the non-resected pts were treated with chemo-radiation, 14% with radiation alone, 7% chemotherapy and immunotherapy, 4.7% immunotherapy alone and 2.3% chemotherapy alone. 7% received palliative radiation followed by chemo or immunotherapy, 7% had follow-up alone. Conclusions: The rate of no surgical resection in this real-world multi-national cohort was 13%, in line with the rate in reported studies. Most un-resected pts underwent appropriate staging. Most were male, with high rate of T3/T4. Survival rate at 12 months was 73.7%. The most common causes for no surgery were PD or being upfront unresectable. The patients with the worst outcome were those who experienced PD during NACT-I. N (% out of 43 non-resected) Male (%) Age (median) PET Done prior to any therapy (%) Brain MRI staging (%) Documented MDT decision of NACT-I (%) Documented surgeon evaluation prior to NACT-I decision (%) T3-4 (%) N2a/b (9th V TNM; %) Survival rate at 12 month (95% CI) 43 (100.0) 69.8 71 95.3 95.0* 96.6* 86.2* 69.8 40.5 73.7% (50.5-87.2%) PD 15 (34.9) 80.0 67 93.3 100.0* 100.0* 92.3* 80.0 40.0 68.2% (14.2-89.7%) In retrospect not resectable 9 (20.9) 55.6 69 100.0 100.0 100.0* 50.0* 77.8 33.3 76.2% (33.2-93.5%) In retrospect not operable 5 (11.6) 80.0 71 100.0 60.0 100.0* 33.3* 40.0 20.0 100.0% (100.0-100.0%) Toxicity 5 (11.6) 80.0 72 100.0 100.0 100.0* 100.0* 80.0 80.0 80.0% (20.4-96.9%) Patient refusal 3 (7.0) 0.0 72 100.0 100.0 100.0 100.0 66.7 33.3 100% (100.0-100.0%) Other ** 6 (14.0) 83.3 75 83.3 100.0* 75.0* 100.0 50.0 40.0* 50.0% (11.1-80.4%) Percentages relate to the total of each row, besides 1st column relating to total of 43. *% of available data. **Death (n=3), intra-operative decision (n=2), additional malignancy (n=1).