Our study suggests that HPD is more common with PD-1/PD-L1 inhibitors compared with chemotherapy in pretreated patients with NSCLC and is also associated with high metastatic burden and poor prognosis in patients treated with PD-1/PD-L1 inhibitors. Additional studies are needed to determine the molecular mechanisms involved in HPD.

Pretreatment LIPI, combining dNLR greater than 3 and LDH greater than ULN, was correlated with worse outcomes for ICI, but not for chemotherapy, suggesting that LIPI can serve as a potentially useful tool when selecting ICI treatment, raising the hypothesis that the LIPI might be useful for identifying patients unlikely to benefit from treatment with an ICI.

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9107 Background: HPD was described in 13.8% of NSCLC pts upon single-agent IO and correlated with high metastatic burden and poor prognosis. Other progression (PD) patterns as FP and ED within 12 weeks have been reported respectively in 4.7% and 5.6% of atezolizumab treated NSCLC pts. Whether FP/ED and HPD are different or overlapping patterns is currently unknown. Methods: We analyzed FP, ED and HPD in a multicentric (8 centers) retrospective cohort of IO treated NSCLC pts (11/2012-04/2017). Eligibility criteria required 2 CT scans before and one after IO start. HPD was defined as RECIST v 1.1 PD at first CT scan and a variation per month of tumor growth rate (TGR upon IO – TGR before IO) > 50%. ED was defined as deaths due to disease PD within 12 wks of IO start. FP was defined as ≥ 50% increase in the sum of long diameters within 6 weeks (wks) from baseline. The associations between PD patterns and pts’ characteristics were performed using Fisher or t-student tests. Median overall survival (mOS) was estimated by Kaplan-Meier method and compared by log-rank test. Results: Out of 406 NSCLC pts, 46% were ≥65 years, 72% had non-squamous NSCLC, > 90% received single agent IO in ≥2 line. 56 (13.8%) were HPD by TGR analysis. Among 72 pts (18%) who performed a CT scan within 6 wks after IO start, 6 (8.3%) were FP. These 6 FP pts were also classified as HPD by TGR analysis, while the other 50 (89%) of 56 HPD pts were not FP. The rate of PD in ≥ 3 sites (54% vs 0%, p = 0.002), the rate of liver PD (62% vs 5%, p = 0.002), the baseline tumor burden (BTB) (mean 176± 26 mm vs 55 ± 6 mm, p < 0.0001) and the TGR upon IO (mean 439± 119% vs 216 ± 41%, p = 0.03) were significantly higher in FP pts compared to HPD pts who were not FP. At 4.4 months of median follow-up, FP pts had significantly worse mOS compared to HPD pts not FP [0.7 months (95% CI 0.6,0.8) vs 1.6 months (95% CI 1.1, 2.1); p = 0.02]. Of 406 IO treated pts, 46 (11%) were ED within 12 wks, and 21 (46%) of ED pts had also HPD by TGR analysis. Conclusions: FP and ED are not a surrogate of HPD. FP occurs in a small subgroup (11%) of HPD and correlates with more aggressive features (PD in ≥3 sites, liver-PD, high BTB, high TGR upon IO) and worse OS. ED within 12 wks overlapped with HPD for only 46% of pts.