ESTRO 2024 - Abstract Book

S1588

Clinical - Lung

ESTRO 2024

Secondary endpoints included overall-survival, pattern of disease progression, distant PFS, response to induction therapy, overall response, duration of response, toxicity, and symptom-specific and global quality of life.

Results:

Forty-nine patients were enrolled (11/2019 - 7/2022), with a median follow-up of 22 months until 12/5/2023. The median age of the patients was 65 years and 59% had an adenocarcinoma. Almost two-thirds of the patients (65%) had a solitary metastasis and 12% had brain metastases. Two patients never started treatment and of the 47 patients who started the induction treatment, 35 patients (74%) proceeded to definitive local treatment of the locoregional primary tumour after the 3-month restaging (surgery: 11; radiotherapy: 24). Reasons for not proceeding to definitive local therapy were disease progression (10 patients; 83%) and death (2 patients; 17%, one lung infection and one thromboembolic event).

Based on the trial design, the primary hypothesis was tested in the first 42 evaluable patients. With the 14 (33%) patients who reached 1 year without progression, the null hypothesis could not be rejected.

For all patients enrolled, the 1-year PFS rate was 45% (95% CI: 31%-58%) and the median PFS was 9.4 months (95% CI: 6.4 - 12.2). A total of 31 patients progressed during follow-up, with progression occurring in the primary tumour (n=9), oligometastases (n=2), in regional lymph nodes (n=5) or as new distant metastases (n=20). The 1-year overall survival rate was 75% (60%-85%) with a median overall survival of 18.2 months (12.8 – not evaluable). No fatal treatment-related toxicities were observed, while 16 (34%) patients experienced grade 3 or 4 treatment-related adverse events (AE), including 5 (11%) cases of grade 3 pneumonitis . Notably, all (n=5) grade 4 AEs consisted of haematological toxicities that occurred during the induction phase and were related to the systemic treatment. Results from additional secondary endpoints, namely quality of life assessments, will be included in the presentation.

Conclusion:

The CHESS trial did not meet its primary endpoint with an observed 1-year PFS rate of 45% compared to an expected rate of 50%. Overall, more than a quarter of patients failed treatment early in the induction phase, with distant disease progression being the most common outcome. Safety outcomes for the multimodality treatment combination were consistent with established toxicity profiles and no new AEs were observed. The favourable safety profile and 1-year overall survival of 75% will provide the basis for further intensification of the systemic therapy, and dual immune-checkpoint inhibition with tremelimumab added to durvalumab in a subsequent study cohort.

Keywords: Oligometastases, multimodality treatment, NSCLC

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Poster Discussion

Outcomes following radiotherapy for oligoprogressive NSCLC on immune checkpoint inhibitors.