"Heterogeneity of treatment effect on patients' long-term outcome according to pathological response type in neoadjuvant RCTs for breast cancer."

INTRODUCTION: To provide evidence explaining the poor association between pCR and patients' long-term outcome at trial-level in neoadjuvant RCTs for breast cancer (BC), we performed a systematic-review and meta-analysis of all RCTs testing neoadjuvant treatments for early-BC and reporting the hazard ratio of DFS (HRDFS) for the intervention versus control arm stratified by pathological response type (i.e., pCR yes versus no). METHODS: The objective was to explore differences of treatment effects on DFS across patients with and without pCR. We calculated the pooled HRDFS in the two strata of pathological response (i.e., pCR yes versus no) using a random-effects model, and assessed the difference between these two estimates using an interaction test. RESULTS: Ten RCTs and 8496 patients were included in the analysis. Patients obtaining pCR in the intervention-arm had a higher, although not statistically significant, risk of DFS-event as compared with patients obtaining pCR in the control-arm: the pooled HRDFS for the experimental versus control arm was 1.23 (95%CI, 0.91-1.65). On the opposite, the risk of DFS-event was higher for control as compared with the intervention-arm in the stratum of patients without pCR: the pooled HRDFS was 0.86 (95%CI, 0.78-0.95). Treatment effect on DFS was significantly different according to pathological response type (interaction test p: 0.014). CONCLUSION: We reported new evidence that contributes to explaining the poor surrogacy value of pCR at trial-level in neoadjuvant RCTs for early-BC.

Outcomes of patients with advanced solid tumors who discontinued immune-checkpoint inhibitors: a systematic review and meta-analysis.

Background: The outcome of patients with metastatic tumors who discontinued immune checkpoint inhibitors (ICIs) not for progressive disease (PD) has been poorly explored. We performed a meta-analysis of all studies reporting the clinical outcome of patients who discontinued ICIs for reasons other than PD. Methods: We searched PubMed, Embase and Scopus databases, from the inception of each database to December 2023, for clinical trials (randomized or not) and observational studies assessing PD-(L)1 and CTLA-4 inhibitors in patients with metastatic solid tumors who discontinued treatment for reasons other than PD. Each study had to provide swimmer plots or Kaplan-Meier survival curves enabling the reconstruction of individual patient-level data on progression-free survival (PFS) following the discontinuation of immunotherapy. The primary endpoint was PFS from the date of treatment discontinuation overall and according to tumor histotype, type of treatment and reason of discontinuation. The Combersure's method was used to estimate meta-analytical non-parametric summary survival curves assuming random effects at study level. Findings: Thirty-six studies (2180 patients) were included. The pooled median PFS (mPFS) was 24.7 months (95% CI, 18.8-30.6) and the PFS-rate at 12, 24, and 36 months was respectively 69.8% (95% CI, 63.1-77.3), 51.0% (95% CI, 43.4-59.8) and 34.0% (95% CI, 27.0-42.9). Univariable analysis showed that the mPFS was significantly longer for patients with melanoma (43.0 months), as compared with non-small cell lung cancer (NSCLC, 13.5 months) and renal cell carcinoma (RCC, 10.0 months; between-strata comparison test p-value < 0.001); for patients treated with anti-PD-(L)1 + anti-CTLA-4 as compared with anti-PD-(L)1 monotherapy (44.6 versus 19.9 months; p-value < 0.001), and in NSCLC when the reason of treatment discontinuation was elective as compared with toxicity onset (19.6 versus 4.8 months; p-value = 0.003). The multivariable analysis confirmed these differences. Interpretation: The long-term outcome of patients who stopped ICIs for reasons other than PD was substantially affected by clinicopathological features: PFS after treatment discontinuation was longer in patients with melanoma, and/or treated with anti-PD-(L)1 + anti-CTLA-4, and shorter in patients with RCC or in those patients with NSCLC who stopped treatment for toxicity onset. Funding: The Italian Ministry of University and Research (PRIN 2022Y7HHNW).