Investigation of efficacy of two different chemotherapy protocols used in neoadjuvant chemotherapy in clinical stages II-IV canine malignant mammary tumours

The first aim of this study is to demonstrate the clinical efficacy and reliability of two different neoadjuvant chemotherapy (NAC) protocols consisting of doxorubicin/cyclophosphamide (AC) and paclitaxel in dogs with clinical stages II-IV canine malignant mammary tumours (CMTs). Secondly, to determine the Luminal A, Luminal B, HER2-positive and triple-negative molecular subtypes and their value in predicting clinical response to NAC in biopsy samples, and thirdly, to reveal the changes in Ki-67, human epidermal growth factor receptor type 2 (HER2), oestrogen receptor (ER), and progesterone receptor (PgR) expression levels induced by NAC. Thirty dogs with clinical stages II-IV CMTs (T1-3N0-1M0) according to the modified TNM system were included in the study. Dogs in group-1 (n = 15) AC combination and dogs in group-2 (n = 15) were administered paclitaxel. Partial response (PR) was the most common clinical response in both treatment groups (66.66% and 86.66%, respectively). There was no difference between the groups regarding clinical response parameters (p = .001). The rate of treatment responders was higher than the rate of non-responders in both groups (p < .001). The adverse effects observed in both groups were mostly limited to grades 1 and 2 and all were easy to manage. The most frequently detected molecular subtype was Luminal A (59.25%). Complete response (CR) was achieved in 33.33% of dogs with triple-negative CMT in the AC group and 14.29% of the Luminal A subtype in the paclitaxel group. Alterations in Ki-67, HER2, ER, and PgR expressions after chemotherapy were not statistically significant (p > .05). As a result, we have shown that these neoadjuvant chemotherapy protocols are effective and safe alternative treatment options for CMTs.

Breast cancer biomarkers before and after neoadjuvant chemotherapy: does repeat testing impact therapeutic management?

In patients treated with neoadjuvant chemotherapy (NAC), there is no consensus on retesting biomarkers within the excision specimen. Our aim was to investigate the clinical relevance of biomarker changes post-NAC at a large tertiary medical center. A retrospective search was performed to identify cases from 2012 to 2015 with needle biopsy-confirmed invasive breast carcinoma treated with NAC and subsequent excision containing residual invasive tumor. Biomarkers (estrogen receptor [ER], progesterone receptor [PR], and HER2/neu [HER2]) were performed on all pre-NAC biopsies. One hundred fifty-four NAC-treated cases were identified in which 83 (54%) had repeat testing of at least 1 biomarker on the surgical specimen. Twenty-five (30%) of 83 repeated cases demonstrated changes in pre-NAC biopsy versus post-NAC resection biomarker status. There was no impact of age or grade on biomarker status changes. Tumors that were triple negative at biopsy were more likely to remain triple negative. Clinically relevant changes were identified including the following: (1) ER negative to ER positive, 2 (3%) of 75; (2) PR negative to PR positive with ER negative both pre- and post-NAC, 2 (3%) of 73; and (3) HER2 negative to positive, 1 (1%) of 77. Four of 5 of the changes led to modifications of the adjuvant treatment regimen, including the addition of adjuvant tamoxifen, anastrazole, or trastuzumab. In summary, post-NAC biomarker repeat testing in patients with breast cancer impacts therapeutic management in a small subset of patients and therefore, repeat testing may be considered for patients that are hormone receptor and/or HER2 negative before NAC.

[89Zr]Trastuzumab: Evaluation of Radiation Dosimetry, Safety, and Optimal Imaging Parameters in Women with HER2-Positive Breast Cancer

PURPOSE

The purpose of the present study is to evaluate safety, human radiation dosimetry, and optimal imaging time of [89Zr]trastuzumab in patients with HER2-positive breast cancer.

PROCEDURES

Twelve women with HER2-positive breast cancer underwent [89Zr]trastuzumab positron emission tomography (PET)/X-ray computed tomography (CT) twice within 7 days post-injection. Biodistribution data from whole-torso PET/CT images and organ time-activity curves were created using data from all patients. Human dosimetry was calculated using OLINDA with the adult female model.

RESULTS

High-quality images and the greatest tumor-to-nontumor contrast were achieved with images performed 5 ± 1 day post-injection. Increased [89Zr]trastuzumab uptake was seen in at least one known lesion in ten patients. The liver was the dose-limiting organ (retention of ∼12 % of the injected dose and average dose of 1.54 mSv/MBq). The effective dose was 0.47 mSv/MBq. No adverse effects of [89Zr]trastuzumab were encountered.

CONCLUSION

[89Zr]trastuzumab was safe and optimally imaged at least 4 days post-injection. The liver was the dose-limiting organ.