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In the tumour microenvironment, IL-1α promotes neoangiogenesis, matrix remodelling, tumour proliferation, chemoresistance, and metastases. Highly expressed in human colorectal cancers, IL-1α is associated with poor prognosis. XB2001, a fully human monoclonal antibody neutralizing IL-1α, was evaluated for safety and preliminary efficacy with trifluridine/tipiracil (FTD/TPI) and bevacizumab in metastatic colorectal cancer patients previously treated with oxaliplatin- and irinotecan-based chemotherapies. This single institution, phase 1 study used a 3 + 3 design to assess XB2001 at doses of 250 mg, 500 mg and 1000 mg every 14 days, associated with FTD/TPI 35 mg/m² (days 1-5 and 8-12, every 28 days) (NCT05201352). The Maximum Tolerated Dose of XB2001 + FTD/TPI was then associated in combination with bevacizumab (5 mg/kg, days 1 and 15). Safety, efficacy, pharmacokinetics and pharmacodynamics were assessed. Seventeen patients (median age: 67.4 years) were enroled. No patient exhibited dose-limiting toxicity at any dose. The most common treatment-related adverse events (TRAE) of any grade (G) were diarrhoea (35.3%), nausea (47.1%) and anaemia (35.3%). G3-4 TRAE were neutropenia (17.6%) hypertension and infection (5.9% each). The RP2D (recommended phase 2 dose) of XB2001 was 1000 mg. The disease control rate was 76%, with 23% of patients achieving an objective response, including one complete response. Response and longer progression-free survival were associated with a decrease in serum IL-6 levels during therapy. High intratumoral IL-1α expression at baseline and CD8/PD-L1 infiltration are associated with a better progression-free survival. The combination of XB2001 with FTD/TPI and bevacizumab is feasible and safe, and showed encouraging clinical activity in chemotherapy-resistant mCRC., Competing Interests: Competing interests: F.G. has received honoraria for oral communications from Lilly, Sanofi, BMS, Astra Zeneca and Amgen, funding for clinical trials by Astra Zeneca, travel grants from Roche France, Amgen and Servier, and has served as an advisory board member for Merck Serano, Amgen, Roche France and Sanofi, all outside the scope of this submitted work. The trial was supported by grants from the French National Cancer Institute (PHRC-K19-077). XB2001 was provided by Xbiotech. All other authors declare no conflicts of interest., (© 2025. The Author(s).)

SOLAR-1 and BYLieve trials documented the efficacy of the PI3K-inhibitor alpelisib in pre-treated PIK3CA-mutant, hormone receptor-positive, HER2-negative (HR+/HER2-) advanced breast cancer (ABC) patients. We report here real-life data of patients prospectively registered in the French alpelisib early access program (EAP) opened to PIK3CA-mutant HR+/HER2- ABC patients treated with alpelisib and fulvestrant. Primary endpoint was PFS by local investigators using RECIST1.1. Eleven centers provided individual data on 233 consecutive patients. Patients had received a median number of 4 (range: 1-16) prior systemic treatments for ABC, including CDK4/6 inhibitor, chemotherapy, fulvestrant and everolimus in 227 (97.4%), 180 (77.3%), 175 (75.1%) and 131 (56.2%) patients, respectively. After a median follow-up of 7.1 months and 168 events, median PFS was 5.3 months (95% CI: 4.7-6.0). Among 186 evaluable patients, CBR at 6 months was 45.3% (95% CI: 37.8-52.8). In multivariable analysis, characteristics significantly associated with a shorter PFS were age < 60 years (HR = 1.5, 95% CI = 1.1-2.1), >5 lines of prior treatments (HR = 1.4, 95% CI = 1.0-2.0) and the C420R PI3KCA mutation (HR = 4.1, 95% CI = 1.3-13.6). N = 91 (39.1%) patients discontinued alpelisib due to adverse events. To our knowledge, this is the largest real-life assessment of alpelisib efficacy. Despite heavy pre-treatments, patients derived a clinically relevant benefit from alpelisib and fulvestrant., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

There is little data concerning the implications of PIK3CA mutations outside of the known hotspots described in ER+/HER2- metastatic breast cancer (mBC). Similarly, PIK3R1 mutations could also lead to activation of PI3K pathway, but are poorly described. We determined the incidence and type of all somatic PIK3CA and PIK3R1 mutations by whole exome sequencing (WES) in a pan-cancer cohort of 1200 patients. Activation of the PI3K pathway was studied using phospho-AKT immunohistochemistry. Associations between PIK3CA/PIK3R1 mutations and response to chemotherapy were studied in mBC cases. We found 141 patients (11.8%) with a PIK3CA and/or PIK3R1 mutation across 20 different cancer types. The main cancer subtype was mBC (45.4%). Eighty-four mutations (62.2%) occurred in the three described hotspots; 51 mutations occurred outside of these hotspots. In total, 78.4% were considered activating or probably activating. Among PIK3R1 mutations, 20% were loss of function mutations, leading to a constitutional activation of the pathway. Phospho-AKT quantification in tumor samples was in favor of activation of the PI3K pathway in the majority of mutated tumors, regardless of mutation type. In ER+/HER2- mBC, first line chemotherapy efficacy was similar for PIK3CA-mutated and PIK3CA-WT tumors, whereas in triple negative mBC, chemotherapy appeared to be more effective in PIK3CA-WT tumors. In this large, real-life pan-cancer patient cohort, our results indicate that PIK3CA/PIK3R1 mutations are widely spread, and plead in favour of evaluating the efficacy of PI3K inhibitors outside of ER+/HER2- mBC and outside of hotspot mutations., (© 2023. The Author(s).)