Background: Trastuzumab deruxtecan (TDXd) is an antibody–drug conjugate that has demonstrated impressive activity in randomized controlled clinical trials in the context of patients with HER2-amplified and HER2-low metastatic breast cancer. We aimed to review the activity and adverse event profile of TDXd in heavily pretreated breast cancer patients in real practice. Methods: We describe a single-center retrospective case series of metastatic breast cancer patients who were treated with TDXd. The outcomes of interest were the overall response rate, overall survival, progression-free survival and grade 4–5 adverse events. Objective responses and PFS were assessed in accordance with RECIST 1.1 criteria. Results: We identified 38 patients treated with TDXd. Of these, 15 patients had classically defined HER2-positive (HER2+) breast cancer, 4 of whom had active central nervous system (CNS) metastases. A total of 23 patients had HER2-low breast cancer, 2 of whom had active CNS disease. Of the 33 patients evaluable for response, 21 (63%) patients had a response to treatment, including three (9%) complete responses. Outcomes were similar between patients with a HER2+ and HER2-low status, as well as in patients with or without CNS metastases. No patients experienced grade 4 or 5 toxicities, and four of thirty-eight patients (10.5%) experienced pneumonitis (two patients with grade 3 pneumonitis, one patient with grade 2 and one patient with grade 1), resulting in TDXd discontinuation for three patients (with steroid administration in two patients). Conclusions: TDXd demonstrates impressive activity with manageable adverse event profiles in this heavily pretreated population that includes patients with active CNS metastases.

To assess whether high Ki-67 protein expression level could independently predict the distant recurrence in early-stage breast cancer with low Oncotype Dx scores (≤ 25). This single-center retrospective cohort study included 278 patients with hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2-), T1-2N0M0, low Oncotype Dx recurrence score (RS) (≤ 25) breast cancer. We identified 2 groups: "high Ki-67″ ≥ 15% (n = 130, 47%) and "low Ki-67″ < 15% (n = 148, 53%). Clinical characteristics, treatment and survival were abstracted from chart review. Fisher's exact test was used to assess differences between Ki-67 groups. Cox-regression models were used to assess differences in survival. After a median follow up of 7 years, 13 (4.7%) patients experienced distant metastasis. Recurrence rate was significantly higher in the "high Ki-67″ group 9.2% (12/130) versus the "low Ki-67″ group 0.7% (1/148) (P = .001). Distant metastasis-free survival (dMFS) was significantly shorter in the "high Ki-67″ group (HR 12.90, 95% CI, 12.53-13.27, P = .008). Tumor size ≥ 2 cm was associated with shorter dMFS (HR, 12.90; 95% CI, 12.53-13.27; P < .001). In a multivariable analysis, tumor size ≥ 2 cm and "High Ki-67″ were independent prognosis factors for dMFS. Ki-67 expression level may help to identify a subset of low risk Oncotype Dx patients who could benefit from adjuvant chemotherapy.

Background: Unsolicited patient feedback (compliments and complaints) should allow the healthcare system to address and improve individual and overall patient, family, and staff experiences. We evaluated feedback at a tertiary cancer centre to identify potential areas for optimizing care delivery. Methods: unsolicited feedback submitted to the Patient Relations Department, relating to the Divisions of Medical and Radiation Oncology, at the Ottawa Hospital, was analyzed. Results: Of 580 individual reports submitted from 2016 to 2022, patient demographics were available for 97% (563/580). Median patient age was 65 years (range 17–101), and 53% (301/563) were female. The most common cancer types were breast (127/545, 23%) and gastrointestinal (119/545, 22%) malignancies, and most (64%, 311/486) patients had metastatic disease. Feedback was submitted mainly by patients (291/579, 50%), and predominantly negative (489/569, 86%). The main reasons for complaints included: communication (29%, 162/566) and attitude/conduct of care (28%, 159/566). While feedback rates were initially stable, an increase occurred from 2019 to 2021. Conclusions: Unsolicited feedback remains mostly negative, and relates to physician communication. If we are to drive meaningful changes in care delivery, more standardized means of assessing feedback and implementation strategies are needed. In addition, in an era of increased healthcare provider burnout, strategies to enhance formal positive feedback are also warranted.

Background: Metastatic prostate cancers frequently harbour pathogenic aberrations in Homologous Recombination Repair (HRR) genes that confer sensitivity to PARP inhibitors (PARPi). Therefore, accurate identification of all eligible patients is needed. The development of a circulating tumour DNA (ctDNA) testing alternative is promising as genomic testing of archived tissue leads to a failure rate of up to 30–40% in prostate cancer. Methods: This was a bi-institutional retrospective cohort study of patients with metastatic prostate cancer treated at the Jewish General Hospital or the McGill University Health Center, Montreal, Canada, between 2021 and 2023. Molecular data and treatment information were abstracted from a chart review. Chi-square, Fisher’s exact test, and Mann–Whitney tests were used to assess differences between groups. Results: We identified 484 metastatic prostate cancer patients. Somatic and germline testing for HRR was performed in 55.4% (n = 268) and 20% (n = 97) patients, respectively. Somatic testing was performed on tissue (n = 192, 71.6%) or ctDNA from liquid biopsies (n = 18, 6.7%) or both (n = 58, 21.7%). Pathogenic somatic HRR alterations were detected in 48 patients (17.9%). BRCA2 was the most frequent (n = 17), followed by ATM (n = 11), then CHEK2 (n = 5). Amongst patients with germline testing, 13/97 (13.4%) had pathogenic alterations predicted to lead to deficient HRR, mostly BRCA2 (n = 9), and three had detectable BRCA2 in tissue. Dual testing modality (tissue+ctDNA) significantly enhanced the detection rate of HRR alterations 19/58 (32.7%) vs. 29/210 (13.8%) for single testing modality (tissue or ctDNA), p = 0.008. The rate of inconclusive results was significantly lower in dual testing modality 0/58 (0%) vs. 25/210 in single testing modality (11.9%), p = 0.003. Amongst the 14 patients who had discordant results between liquid and tissue tests, HRR abnormalities were more frequently identified in ctDNA (n = 11) vs. tissue (n = 3). Patients who had HRR deficiency detected only in ctDNA had older tissue samples (median 5.6 years) compared to those who had deficient HRR detected only in tissue (median 0.2 years; p = 0.14). Conclusions: These data highlight a potential role in implementing liquid biopsy—especially in patients who only have older archival tissue available or failed tissue testing—to improve the detection rate of deficient HRR. Our ongoing prospective study will further validate whether the addition of liquid biopsy can identify more patients who are eligible to receive precision therapies by increasing the rate of detection of HRR deficiency compared to routine tissue testing alone.

Brain metastases (BrMs) occur in approximately 30% of cancer patients, causing nearly one-fifth of cancer deaths. While immune checkpoint inhibitors (ICIs) benefit some BrM patients, responses remain highly variable. This variability partly reflects distinct histopathological growth patterns that include minimally invasive (MI) and highly invasive (HI) brain BrMs. Here we show that MI BrMs exhibit robust immune infiltration, whereas HI lesions are immunosuppressed. However, histological differentiation between MI and HI can be challenging because of subjective margin assessment. Here, using highly multiplexed spatial proteomics on 119 tumor sections from 46 patients with BrMs, we identify CHI3L1 as a key mediator of the immunosuppressive microenvironment in HI BrMs. In preclinical models, genetic deletion of CHI3L1 converts immune-cold metastases into lymphocyte-rich, ICI-responsive lesions infiltrated by granzyme B ⁺ CD8 ⁺ T cells. In BrM patients treated with ICI, immunohistochemical quantification of CHI3L1 expression was a stronger predictor of ICI response than traditional MI/HI classification. Thus, CHI3L1 represents a promising biomarker and therapeutic target for BrMs.