Emilia Cocorocchio

Background: The surrogacy of progression-free survival (PFS) for overall survival (OS) at the trial-level in randomized clinical trials (RCTs) testing immune checkpoint inhibitors (ICIs) in patients with advanced non-small cell lung cancers (NSCLC) is influenced by several clinical-pathological factors. However, potential heterogeneity of PFS surrogacy according to patients’ sex has never been investigated. Methods: RCTs testing ICIs as monotherapy or combined with chemotherapy in patients with advanced NSCLC reporting hazard ratios (HRs) for PFS and OS according to patients’ sex were included. The main objective was to assess sex-based heterogeneity in the trial-level association between PFS (surrogate endpoint) and OS (reference endpoint), overall and in subgroups defined by treatment type (ICIs as monotherapy vs ICIs plus chemotherapy). We used the coefficient of determination (R2) to quantify surrogacy. Results: Twenty RCTs, for a total of 7528 male and 3008 female patients, were included. Overall, the association between OS-HR and PFS-HR was moderate: the R2 from a model adjusted by the type of treatment administered in the experimental arm was 0.69 (95% confidence interval [CI] = 0.34 to 0.88). Sex-disaggregated analysis showed heterogeneity in PFS surrogacy: the association was strong in male patients (adjusted R2 = 0.77; 95% CI = 0.56 to 0.89), but poor in female (adjusted R2 = 0.31, 95% CI = 0.03 to 0.63). Consistent results were obtained in subgroups analyses by treatment type, and in cross-validation analysis. Conclusions: In RCTs testing ICIs alone or combined with chemotherapy in patients with advanced NSCLC, PFS is a robust surrogate endpoint for OS in male patients but not in female.

Background: The surrogacy of overall response rate (ORR) or progression-free survival (PFS) for overall survival (OS) at the trial-level in randomized clinical trials (RCTs) testing antibody-drugs conjugates (ADC) has never been investigated. Methods: RCTs testing ADCs in patients with advanced solid tumors and reporting data on OS and PFS and/or ORR were analyzed. The main objective was to assess the trial-level association between the surrogate endpoints (ORR or PFS) and the reference endpoint (OS), overall and in subgroups of trials defined by tumor type, number of previous lines of systemic treatments, and specific ADC features. Results: Twenty-five RCTs, for a total of 26 treatment comparisons and 11 729 patients, were included in the analysis. In 21 comparisons the ADC was administered as monotherapy, and in 16 was tested in patients with breast cancer. The association between the hazard ratio for OS and relative risk of ORR was moderate: the R2 from a model adjusted by tumor type was 0.47 (95% CI = 0.11 to 0.83). The association between the hazard ratios for OS and PFS was strong: the R2 from the adjusted model was 0.79 (95% CI = 0.66 to 0.92). Cross-validation analyses showed similar results. Consistent results were obtained across all the subgroups analyzed, with the notable exception of the subgroup of trials testing ADCs for breast cancer, where the association between OS and ORR appeared strong (R2 = 0.77; 95% CI = 0.51 to 0.90). Conclusions: In RCTs evaluating ADCs in advanced solid tumors, PFS serves as a robust surrogate endpoint for OS, offering greater reliability than ORR and adequately supporting accelerated approval of ADCs in future trials.

After decades of research, improving the efficacy of adjuvant endocrine therapy (ET) for early-stage breast cancer becomes increasingly difficult. Beyond technological breakthroughs and the availability of new classes of drugs, further improvement of adjuvant ET will require applying a rigorous research approach in poorly investigated areas. We critically discuss some key principles that should inform future research to improve ET efficacy, including identifying specific subgroups of patients who can benefit from escalating or de-escalating approaches, optimizing available and new treatment strategies for different clinical contexts, and dissecting the direct and indirect biological effects of therapeutic interventions. Four main issues regarding adjuvant ET were identified as relevant areas, where a better application of such principles can provide positive results in the near future: (i) tailoring the optimal duration of adjuvant ET, (ii) optimizing ovarian function suppression for premenopausal women, (iii) dissecting the biological effects of estrogen receptor manipulation, and (iv) refining the selection of patients to candidate for treatments escalation.

Legends of supplementary figure S1 and S2