PARP inhibitors (PARPi) are effective in tumors with homologous recombination repair (HRR) deficiency (HRD), typically identified by germline/tumor mutations. However, genetic testing may miss intrinsic PARPi sensitivity and resistance. We evaluated strategies to improve detection and longitudinal monitoring of HRD across >500 tumor samples and >20 paired liquid biopsies, integrating genetic, genomic, and functional readouts. HRD was more frequent in high-grade ovarian cancer (HGOC; 52%) than in metastatic breast (mBC; 12%) or prostate cancer (mPC; 20%). Assay concordance was low-to-moderate, underscoring complementarity. RAD51 testing and the genomic instability score identified HRD in tumors lacking pathogenic HRR mutations (6% and 30% in mBC, 38% and 46% in HGOC, 14% and 27% in mPC, respectively). Longitudinal ctDNA sequencing revealed BRCA1/BRCA2 reversion mutations in >30% of post-PARPi mBC samples, which were associated with poor response to subsequent platinum therapy. These findings support the use of complementary HRD biomarkers in tissue and liquid biopsy to guide PARPi use and monitor response.

The sub-study of the INSEMA trial (randomization-2) compares completion axillary lymph node dissection (cALND) with sentinel lymph node biopsy (SLNB) alone in cN0 patients with T1/T2 invasive breast cancer and one to three sentinel node macrometastases undergoing upfront breast-conserving surgery. The key secondary objective is to assess whether the SLNB-alone arm is non-inferior to cALND in terms of invasive disease-free survival (iDFS). Finally, 485 patients were recruited, and 386 patients (cALND: N = 169, SLNB alone: N = 217) were included in the per-protocol set. The median follow-up is 74.2 months. The 5-year iDFS analysis in the per-protocol set demonstrates a non-significant difference between study arms, with a hazard ratio (HR) of 1.69 (95% CI: 0.98-2.94) for SLNB alone compared to cALND. The 5-year iDFS rates are 86.6% (81.0%-90.7%) in the SLNB-alone arm and 93.8% (88.7%-96.6%) in the cALND arm (P = 0.058). The 5-year overall survival rates are 94.9% (90.6%-97.2%) in the SLNB-alone arm and 96.2% (91.7%-98.3%) in the cALND arm (P = 0.663). Locoregional recurrences (LRR) were infrequent, with 5-year incidence rates of 1.1% versus 0.0% (P = 0.405) in the SLNB-alone arm compared to cALND. In summary, no significant differences were observed between SLNB alone versus cALND for iDFS, overall survival, and LRR. Trial registration number: NCT02466737

Accurate assessment of Ki67, a marker of cellular proliferation, is critical for breast cancer diagnostics and treatment decision-making. This study evaluates an automated Ki67-area identification approach, combined with digital image analysis (DIA) for exact Ki67 quantification. A total of 61 tissue samples from breast cancer patients from two clinical trials (GeparSixto and GeparSepto) were analyzed. The supervised DIA workflow employed automated Ki67-stained tumor area identification, followed by automated Ki67 scoring and was quality-controlled by trained pathologists. Comparisons with manual assessments were conducted to evaluate concordance and scoring precision. The DIA approach identified 232 tumor areas across 61 whole slide images (WSIs). The supervised system demonstrated a high correlation with manual scores (r = 0.78), and improved precision (standard deviation between evaluated tumor areas) was noted in therapy-naïve samples (p < 0.001). While manual assessments predominantly employed stepwise increments (5

Background In KEYNOTE-522 (NCT03036488), addition of perioperative pembrolizumab to neoadjuvant chemotherapy significantly improved pathological complete response (pCR), event-free survival (EFS), and overall survival (OS) in early-stage triple-negative breast cancer (TNBC). pCR and EFS results in participants enrolled in Asia were consistent with those in the overall population. We report OS, updated EFS, and safety outcomes in participants enrolled in Asia. Methods Participants with newly diagnosed, high-risk, early-stage TNBC (T1c [N1‒N2] or T2‒T4 [N0‒N2] per AJCC 7th edition) were randomized 2:1 to 8 cycles of neoadjuvant pembrolizumab 200 mg Q3W or placebo plus chemotherapy. After definitive surgery, participants received adjuvant pembrolizumab 200 mg Q3W or placebo for ≤9 cycles. Primary endpoints were pCR (ypT0/Tis ypN0) and EFS. OS was a secondary endpoint. Results Of 1174 randomized participants, 216 were enrolled in Asia. At data cutoff (March 22, 2024), EFS events occurred in 18/136 participants (13.2%) in the pembrolizumab+chemotherapy group versus 22/80 (27.5%) in the placebo+chemotherapy group (HR, 0.43 [95% CI, 0.23‒0.81]); 60-month EFS rates (95% CIs) were 87.4% (80.6%‒92.0%) and 72.1% (60.7%‒80.6%), respectively. In the respective groups, 12/136 (8.8%) and 16/80 participants (20.0%) died (HR, 0.41 [95% CI, 0.19‒0.86]); 60-month OS rates (95% CIs) were 91.9% (85.8%‒95.4%) and 81.1% (70.5%‒88.1%). Treatment-related AEs led to treatment discontinuation in 19/136 participants (14.0%) with pembrolizumab+chemotherapy and 7/79 (8.9%) with placebo+chemotherapy. Conclusions OS and updated EFS outcomes in KEYNOTE-522 participants enrolled in Asia were consistent with those in the overall population and support use of perioperative pembrolizumab+neoadjuvant chemotherapy as a standard-of-care treatment in this setting.

The DestinyBreast (DB)04 and DB06 trials have shown clinical activity of trastuzumab-deruxtecan (T-DXd) in HER2-low and HER2-ultralow metastatic breast cancer. The identification of HER2-low and HER2-ultralow breast cancer is therefore essential for personalized therapy with T-DXd. We evaluated 723 residual tumors from the Penelope-B trial (NCT01864746) and correlated different levels of HER2 protein expression with prognosis and messenger RNA (mRNA) profiles, including HER2 transcripts. In Penelope-B, 57.68% (n = 417) of 723 residual tumors were HER2 low. The HER2-ultralow category was assigned to 109 (15.08%) tumors, and 197 (27.25%) tumors were completely HER2 negative (HER2 0). In Kaplan-Meier analysis, there were no survival differences among these 3 subgroups. There was no significant difference in HER2 mRNA expression between HER2-0 and HER2-ultralow tumors (P = .08). In contrast, there was a highly significant difference in HER2 mRNA expression between HER2-ultralow and HER2-low tumors (P < .0001) and between HER2-low and HER2-positive tumors (P < .0001). The extracellular protease cathepsin L, which has been suggested as a biomarker for extracellular cleavage of T-DXd, was detectable in all HER2-related subgroups and was a negative prognostic factor for invasive disease-free survival and overall survival (P = .0001) in preneoadjuvant core biopsies. In our study, we were able to characterize HER2 low as a clinically relevant and molecular defined tumor group with significantly increased HER2 expression. In contrast, for HER2 ultralow, we did not observe a defined molecular phenotype, despite the clinically relevant regulatory approval of T-DXd also in the ultralow subgroup. Additional investigations are needed to identify biomarkers beyond HER2 for T-DXd response as a basis for refined criteria for treatment eligibility.

Tumour-infiltrating lymphocytes (TILs) are prognostic and predictive biomarkers in breast cancer. High pre-treatment TILs are associated with a favourable prognosis and improved response to systemic therapies. However, the role of TILs in mediating response to radiotherapy in breast cancer remains underexplored, with scarce clinical evidence to date. In this Review, we present an overview of current evidence and potential mechanisms, highlight opportunities for integrating TILs into radiation oncology trials and clinical practice, and call for standardised TIL reporting to accelerate biomarker-driven individualisation of radiotherapy in breast cancer.

BACKGROUND:Tumour-infiltrating lymphocytes (TILs) are a robust prognostic marker in patients with triple-negative breast cancer. Artificial intelligence (AI)-derived computational tools assessing TILs could improve efficiency, but require independent validation against clinical outcomes. We aimed to compare the prognostic performance of AI-derived TIL scores with pathologist-scored TILs in a large, prospectively collected dataset pooled from randomised controlled trials. METHODS:CATALINA was an independent, external validation study using prospectively collected long-term clinical outcome data pooled from seven randomised clinical trials conducted at multiple sites. We independently evaluated two previously validated AI pipelines that generate five computationally assessed tumour-infiltrating lymphocyte (cTIL) scores by masked, independent deployment of locked models. cTIL scores were correlated with the mean of the pathologist-scored stromal TILs (sTILs) in 220 digitised haematoxylin and eosin whole slide images in a cohort of patients with early-stage triple-negative or HER-2 positive breast cancer, previously scored by trained pathologists in a TIL-reproducibility study. Prognostic performance was assessed in a separate cohort of patients with early triple-negative breast cancer pooled from seven prospective, randomised adjuvant trials. Multivariable Cox regression models adjusted for clinicopathological factors and study heterogeneity assessed associations of cTIL score and sTIL score with invasive disease-free survival, distant disease-free survival, and overall survival. 5-year discrimination was estimated using time-dependent area under the receiver operating characteristic curve (AUC). FINDINGS:Individual data were collated from 1759 patients, of whom 1356 had complete clinicopathological data, pathologist sTIL scores, and cTIL scores available. Modest correlation (r 0·375-0·473) was observed between cTIL scores and the mean pathologist sTIL score. Both sTIL and cTIL were independently associated with 5-year invasive disease-free survival, distant disease-free survival, and overall survival after adjustment for clinicopathological factors (hazard ratio for invasive disease-free survival was 0·73 [95% CI 0·66-0·82]; q<0·0001, distant disease-free survival was 0·70 [0·61-0·79]; q<0·0001, and overall survival was 0·72 [0·63-0·82]; q<0·0001 for sTIL scores and 0·80 [0·73-0·89]; q<0·0001, 0·77 [0·69-0·86]; q<0·0001, and 0·79 [0·70-0·88]; q=0·0002, respectively, for percentage_lymphocyte scores). In models adjusted for clinicopathological variables and sTIL score, cTIL score did not maintain a statistically significant prognostic association. Both sTIL and cTIL scores improved the 5-year AUC over clinicopathological variables alone, while cTIL score did not significantly further improve AUC when combined with clinicopathological variables and sTIL score. INTERPRETATION:Two cTIL models deployed entirely without retraining or modification provided statistically significant prognostic information and improved risk discrimination compared with clinicopathological variables alone in this large, platform-based, independent validation study. Although cTIL score did not incrementally improve prognostication compared with models combining clinicopathological variables with sTIL score, these findings support the application of cTILs as a reproducible prognostic biomarker, particularly in settings where routine or widespread pathologist assessment is unavailable. FUNDING:Breast Cancer Research Foundation (USA).

BACKGROUND:Stromal tumour-infiltrating lymphocytes (sTILs) are prognostic in early-stage HER2-positive breast cancer, but their role in the context of dual HER2 blockade remains undefined. We evaluated manual, digital, and artificial intelligence (AI)-based sTIL quantification, together with AI-derived spatial metrics, for prognostic and treatment-benefit stratification using tumour samples from the phase 3 APHINITY trial. METHODS:In the APHINITY trial, 4805 patients were randomly assigned to receive chemotherapy plus trastuzumab with pertuzumab or chemotherapy plus trastuzumab with placebo. Median follow-up was 74·1 months (IQR 68·3-75·4). We analysed 4262 haematoxylin and eosin-stained images using manual assessment, an automated digital approach, AI-based lymphocyte quantification (AI percentage lymphocytes), and two AI-derived spatial features (AI-TIL and immune hotspot). Interobserver reproducibility was assessed in 262 randomly chosen tumour samples scored independently by five pathologists. Multivariable Cox models were used to assess associations between TIL levels and invasive disease-free survival (primary outcome in APHINITY), distant recurrence-free interval, and overall survival. The heterogeneity of pertuzumab benefit was evaluated using subgroup analyses, subpopulation treatment effect pattern plot analyses, and nested Cox models with treatment-by-biomarker interaction terms. FINDINGS:Manual scoring showed high interobserver reproducibility (intraclass correlation coefficient 0·84 [95% CI 0·79-0·88]). Concordance between manual and automated methods was modest. AI-based scoring (AI percentage lymphocytes) reclassified 120 (11·6%) of 1035 node-positive tumours from immune-low (by manual scoring) to immune-high; this subgroup of patients showed greater separation of 5-year invasive disease-free survival curves between pertuzumab and placebo groups compared with patients whose tumours were concordantly classified as immune-low by both manual and AI-based approaches. Higher levels of TILs were associated with improved invasive disease-free survival for all sTIL measurement approaches and spatial measurements (hazard ratios [HRs] 0·41-0·93). Pertuzumab was associated with improved invasive disease-free survival at higher sTIL levels across all measurement approaches (HRs 0·36-0·48), but was not associated with higher values of spatial measures. The largest 6-year absolute improvements with pertuzumab were observed in patients with node-positive disease whose tumours scored in the highest level of immune infiltration of manual sTIL scoring (≥70·0%; mean absolute improvement 12·1 percentage points [SD 2·8]). In nested prognostic and predictive models, AI-based immune hotspot scores provided the most consistent additional information when combined with any sTIL measurement (all p<0·010). INTERPRETATION:Standardised manual sTIL scoring was reproducible, and digital and AI-based methods showed consistent prognostic stratification and potential for treatment-benefit stratification despite only modest correlation between platforms. AI spatial metrics provided complementary information beyond sTIL density and could support more scalable immune assessment. Future studies are needed to validate these approaches in independent cohorts and to clarify their clinical utility for stratifying contemporary HER2-directed therapies. FUNDING:None.

Triple-negative breast cancer (TNBC) is an aggressive subtype with an activated tumor immune microenvironment. The multicenter, multinational, double-blinded NSABP B-59/GeparDouze trial evaluated the addition of atezolizumab (atezo) (773 patients randomized) or placebo (777 patients) to sequential taxane-carboplatin-anthracycline-based neoadjuvant chemotherapy in stage II-III TNBC. The addition of atezo did not significantly improve the primary endpoint of event-free survival (EFS) (HR, 0.80 (95% CI, 0.062-1.03); stratified log-rank P = 0.083, 4-year EFS rates difference 3.3%). The HR for overall survival was 0.86 (95% CI, 0.62-1.19), with a 4-year benefit of 0.7%. Prespecified subgroup analyses suggested heterogeneity in EFS, with benefit of atezo in patients presenting with clinical lymph node involvement (Pinteraction = 0.039). Treatment-emergent adverse events with grades ≥3 were reported in 75.3% (atezo) versus 73.4% (placebo), and immune-related adverse events were reported in 27.6% (atezo) versus 11.4% (placebo). A total of 196 (25.5%) patients discontinued atezo and 143 (18.8%) patients discontinued placebo in the neoadjuvant phase. In an exploratory mRNA-based subset analysis, patients with basal-like immune-activated tumors may have benefited from atezo. TNBC subtyping to identify basal-like immune-activated tumors and quantification of tumor-infiltrating lymphocytes to identify tumors with high tumor-infiltrating lymphocyte counts could be a promising strategy to identify patients who benefit from the addition of immune checkpoint inhibitors to neoadjuvant chemotherapy. ClinicalTrials.gov registration: NCT03281954 .

[This corrects the article DOI: 10.1055/a-2612-3790.].

The phase II GeparNuevo trial investigated whether adding durvalumab to neoadjuvant chemotherapy (NACT) only in patients with early triple-negative breast cancer cT1b-cT4a-d would improve pathologic complete response (pCR) rate and patient survival. Hundred and seventy-four patients were randomly assigned to receive durvalumab or placebo concurrently with nab-paclitaxel once per week and followed by dose-dense epirubicin and cyclophosphamide. With 86.4 months of median follow-up compared with the previously reported 43.7 months, durvalumab showed sustained significant improvements in long-term outcomes as defined by STEEP compared with placebo regarding not only invasive disease-free survival (iDFS; hazard ratio [HR], 0.56 [95% CI, 0.32 to 0.99]; stratified log-rank P = .0431), but also distant disease-free survival (DDFS; HR, 0.41 [95% CI, 0.21 to 0.80]; P = .0069) and overall survival (OS; HR, 0.33 [95% CI, 0.14 to 0.79]; P = .0085). All analyses were stratified by stromal tumor-infiltrating lymphocytes (sTILs) at baseline (low [≤10%], intermediate [11%-59%], high [≥60%]). In exploratory subgroup analysis, patients with nodal involvement at baseline demonstrated a greater iDFS benefit (HR, 0.33 [95% CI, 0.144 to 0.771]; P = .01; Pinteraction = 0.045). sTILs in residual disease (RD) could be assessed in 39/71 patients without pCR. Post hoc analyses by sTILs high (>10%) versus low (≤10%) in RD showed estimated 7-year iDFS rates of 92.3% (95% CI, 56.6 to 98.9) and 51.4% (95% CI, 29.2 to 69.7), respectively. Hence, adding durvalumab to dose-dense NACT without adjuvant continuation of checkpoint inhibition improved long-term survival outcomes, irrespective of the extent of pathologic response. This underscores the necessity to re-evaluate the adjuvant continuation of checkpoint inhibition.

Background High-grade serous ovarian cancer (HGSOC) is commonly accompanied by malignant ascites, a clinically relevant tumor niche that promotes immune evasion, metastasis, and treatment resistance. Although natural killer (NK)-cell dysfunction has been described in ovarian cancer, the broader innate lymphoid landscape of ascites and the mechanisms linking ascites-derived signals to innate immune suppression remain insufficiently resolved.Methods We performed single-cell RNA sequencing of NK/innate lymphoid cells from ovarian cancer ascites to define cellular heterogeneity and differentiation states. Functional assays assessed NK-cell cytotoxicity, degranulation, and receptor expression following exposure to patient-derived ascites, with or without transforming growth factor-β (TGF-β) receptor inhibition. Proteomic profiling was used to characterize the soluble ascites milieu, and clinical associations were examined for innate lymphoid subsets.Results Single-cell analysis identified eight transcriptionally distinct NK/innate lymphoid states, including cytotoxic, precursor, early-like, tolerant/immunoregulatory, regulatory, proinflammatory, and innate lymphoid populations. Ovarian cancer ascites was characterized by depletion of cytotoxic and precursor NK-cell states together with enrichment of early-like, tolerant, regulatory, pro-inflammatory, and innate lymphoid cell (ILC) populations. Trajectory analysis indicated impaired maturation toward terminally differentiated cytotoxic NK cells. Notably, ascites contained an expanded population of programmed cell death protein 1 (PD-1)+ ILC2s, which were more abundant in patients with shorter progression-free survival. In functional assays, short-term exposure of healthy donor NK cells to ascites suppressed degranulation and tumor-cell killing, reduced expression of activating receptors including NKp30 and DNAM-1, increased inhibitory receptor expression, and shifted NK cells toward a CD56highCD16low phenotype. Proteomic profiling supported a soluble milieu consistent with type 2 immune skewing and NK-cell suppression. Importantly, TGF-β receptor inhibition partially restored NK-cell activation and function in the presence of ascites.Conclusions HGSOC ascites establishes a type 2-skewed immunoregulatory niche that coordinately drives NK cell dysfunction and PD-1+ ILC2 accumulation. The findings identify TGF-β-linked suppression and ascites-associated immune regulators as candidate immunotherapeutic vulnerabilities for restoring antitumor immunity in ovarian cancer.

Representativeness of Study Participants

Breast cancer remains the most frequently diagnosed cancer among women worldwide, and its burden is particularly severe in regions affected by conflict and war. In these settings, oncology care is often disrupted by the destruction of healthcare infrastructure, displacement of populations, shortages of trained personnel, and limited access to diagnostics and treatment. This paper presents a multidisciplinary, practice-oriented, and resource-stratified framework for delivering breast cancer care in conflict zones, offering practical guidance for clinicians, healthcare workers, and humanitarian organizations. Drawing on literature, field experiences, and expert insight across oncology, pathology, radiology, surgery, radiation oncology, psycho-oncology, and public health, we outline key challenges and propose context-adapted strategies spanning early detection, diagnosis, treatment, and psychosocial support. Emphasis is also placed on multidisciplinary and collaborative efforts, policy and strong advocacy at local, national, and international levels, as well as ethical considerations in humanitarian settings.

Figure S3: Screening for Patients: HRD Status and g/tBRCA1/2 Mutations

Neuroendocrine neoplasms (NEN) comprise well-differentiated neuroendocrine tumours (NET) and neuroendocrine carcinomas (NEC), whose distinction is clinically critical. Although c-MYC alterations have been implicated in NEC pathogenesis, its expression across NEC subtypes and anatomical sites, as well as in NET, remains incompletely defined. We analysed c-MYC immunohistochemically in 1380 resected NEN using the immunoreactive score (IRS: negative 0–1, weak 2–3, moderate 4–8, strong 9–12). Overall, c-MYC positivity (IRS ≥ 2) was observed in 13.3% of NEN. Expression was detected in 43% of NEC (164/381), including strong staining in 19.4%, whereas it was rare in NET and pulmonary carcinoids (20/999; 2%; p ≤ 0.001 ). Within NEC, c-MYC expression was enriched in LCNEC and MiNEN compared with SCNEC and Merkel cell carcinoma ( p ≤ 0.001 ) and occurred more often in gastroenteropancreatic than in pulmonary NEC (57.6% vs. 37.3%; p ≤ 0.001 ). Among NET, G3 tumours showed the highest positivity rate (6/35; 17.1%), although this was significantly lower than in NEC ( p ≤ 0.001 ), with strong expression observed in only one NET G3 (2.9%). No association between c-MYC expression and survival was identified in either NEC or NET. Our study confirms c-MYC expression as a common event in NEC and highlights differences across histological subtypes and anatomical sites, while demonstrating its absence in most low-proliferative NET. A subset of NET G3 tumours exhibits weak to moderate c-MYC expression at levels far below those seen in NEC, suggesting that strong c-MYC positivity may support an NEC classification in borderline cases but does not represent a definitive discriminatory marker.

Breast cancer (BC) is the most prevalent malignancy in women, with hormone receptor-positive, HER2-negative (HR+/HER2−) tumors representing ~70% of cases. While CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy have transformed treatment for metastatic HR+/HER2− BC, acquired resistance remains a major obstacle. Using HR+/HER2− BC models with acquired resistance to the CDK4/6 inhibitors Palbociclib or Ribociclib, we uncovered a metabolic vulnerability in highly resistant clones, mediated by mTORC1 hyperactivation and autophagy suppression. Gene expression profiling revealed enrichment of glycolysis and mTORC1 pathways in CDK4/6i-resistant cells, which manifested as heightened sensitivity to the metabolic inhibitors Metformin and Dichloroacetate (DCA). Mechanistically, mTORC1 overactivation impaired autophagy via ULK1-Ser757 phosphorylation, as confirmed by LC3 flux assays, leaving resistant cells unable to adapt to energy stress. Treatment with metabolic drugs triggered AMPK activation, ACC inhibition, and PARP cleavage, culminating in apoptosis. Clinically, immunohistochemical analysis of a BC cohort revealed a significant correlation between mTORC1 activity (p4E-BP1T37/46) and autophagy suppression (p62 accumulation), supporting the translational relevance of this axis. Our findings propose mTORC1-mediated autophagy defects as a biomarker for metabolic vulnerability in CDK4/6i-resistant BC, offering a rationale for targeting these tumors with metabolic therapies to overcome resistance.

We prospectively evaluated surgical outcomes following neoadjuvant pembrolizumab or placebo added to neoadjuvant chemotherapy among participants with early-stage triple-negative breast cancer (TNBC) in the phase 3 KEYNOTE-522 study (NCT03036488). Participants with previously untreated, early-stage TNBC (AJCC stage T1c N1–2 or T2–4 N0–2) were randomized 2:1 to neoadjuvant pembrolizumab/placebo plus paclitaxel-carboplatin for 4 cycles, followed by pembrolizumab/placebo plus doxorubicin/epirubicin and cyclophosphamide for 4 cycles. After definitive surgery, participants received adjuvant pembrolizumab/placebo Q3W for 9 cycles. Surgery type and timing, nodal status postsurgery, and adverse events within 30 days following surgery were recorded. Among 1,174 randomized participants (pembrolizumab plus chemotherapy, n = 784; placebo plus chemotherapy, n = 390), similar proportions underwent breast-conserving surgery (45.2 https://www.clinicaltrials.gov/study/NCT03036488

Table S2: Secondary endpoints by treatment arm and pCR