Main Session
Sep 29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care

3461 - Induction Immunotherapy (+/- Chemotherapy) in Inoperable Stage III Non-Small Cell Lung Cancer (NSCLC)

03:45pm - 05:00pm ET
Poster Hall - Exhibit Hall A
Screen: 20
POSTER

Presenter(s)

Lamees El Nihum, MD, MEng - Fox Chase Cancer Center, Philadelphia, PA

L. I. El Nihum1, H. A. Lemisch2, J. Cui3, L. Zhang3, M. J. Edelman4, and S. S. Kumar1; 1Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, 2Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 3Biostatistics and Bioinformatics Facility, Fox Chase Cancer Center, Philadelphia, PA, 4Division of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, PA

Purpose/Objective(s):

For inoperable stage III NSCLC, the standard of care (SOC) following the PACIFIC trial is concurrent definitive chemoradiotherapy (CRT) followed by adjuvant consolidation immunotherapy (IO). PACIFIC 6 evaluated sequential chemotherapy (CTX), radiation therapy (RT), and IO in patients deemed ineligible for immediate CRT due to co-morbidities or RT field constraints. We extend the approach of PACIFIC 6 in the evaluation of induction IO (+/- CTX) followed by definitive RT in patients deemed ineligible for SOC CRT.

Materials/Methods:

This is a single institution, retrospective study of inoperable stage III NSCLC patients deemed ineligible for CRT who received induction IO (anti-PD-1/L1) +/- platinum-based combination CTX, followed by definitive RT, from 2019-2024. Outcomes were calculated from the first day of IO until progression/death. Median follow-up was estimated using the reverse Kaplan–Meier method. Time-to-event endpoints including overall survival (OS), progression-free survival (PFS), and time to death or distant progression were estimated using the Kaplan-Meier method. Grade 3+ toxicity data were collected for esophagitis and pneumonitis. Demographics and outcomes are reported alongside those of PACIFIC 6 and PACIFIC (Table 1).

Results:

We identified 21 patients with inoperable stage III NSCLC deemed ineligible for CRT who received induction IO +/- CTX, followed by definitive RT. 20/21 (95.2%) patients received induction IO within six months pre-RT, and 1/21 (4.8%) within one year pre-RT (median 6.0 cycles; range 4 to 31). 16/21 (76.2%) patients received CTX within six months pre-RT (median 4.5 cycles). Post-RT IO was administered to 17/21 (81.0%) patients (median 5.0 cycles). Post-RT CTX was administered to 12/21 (57.1%) patients (median 5.5 cycles). With a median follow-up of 49.2 months, median OS and PFS were 35.7 and 14.8 months, respectively. Median time to death or distant progression was 25.0 months. The 2-year OS and PFS were 61.9% and 38.1%. The 2-year death or distant PFS was 52.4%. One patient (4.8%) demonstrated grade 3 esophagitis following RT. One patient (4.8%) demonstrated grade 3 pneumonitis following RT.

Conclusion:

Induction IO (+/- CTX) appears safe and effective in patients deemed ineligible for CRT. PFS outcomes compare favorably to PACIFIC 6 and approach those of PACIFIC. OS outcomes may reflect our sizeable proportion of patients = 65 years of age and with stage IIIC disease, but nevertheless approach those of PACIFIC 6 and PACIFIC. Further exploration of induction IO in both fit and compromised patients is indicated.

Table 1.

 PACIFIC 6

 Our study

 PACIFIC
Age = 65 years

 65.8%

 76.2%

 45.2%
Stage IIIA

 35.9%

 47.6%

 54.0%
Stage IIIB

 52.1%

 19.0%

 57.1%
Stage IIIC

 11.1%

 33.3%

 0.0%
Median OS (months)

 39.0

 35.7

 47.5
Median PFS (months)

 13.1

 14.8

 16.9
2-year OS

 67.2%

 61.9%

 66.3%
2-year PFS

 35.3%

 38.1%

 45.0%