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Breast cancer is the most common malignancy in women, with the majority classified as hormone receptor–positive (HR+) and HER2 receptor–negative (HER2−). After the approval of the CDK4/6 inhibitors, palbociclib, ribociclib and abemaciclib for advanced HR+/HER2− breast cancer, combinations of endocrine therapy (ET) and CDK4/6 inhibitors are becoming routine practice. However, drug resistance remains an important issue. To overcome this, multiple targeted therapies are in development, and several approaches are in clinical trial in combination with ET, including drugs that inhibit CDK7, FGFR, AURKA, HDAC and the PI3K–AKT–mTOR pathway. Triple combinations of investigational drugs with ET and CDK4/6 inhibitors are also being trialled.

Background: The effect of the COVID-19 on breast cancer treatment is unknown. The pandemic’s impact on treatment delivery was assessed in patients undergoing chemotherapy treatment at a major London oncology centre. Methods: Treatment and medical records for all patients attending the chemotherapy unit and on outpatient treatment for breast cancer over an 8 week period (during first lockdown; 23rd March-17th May 2020) were compared to a similar time period in 2019. Results: Breast cancer diagnosis referrals fell by 38% mainly due to screening services halting which had a knock-on effect on patient numbers starting their first treatment (reduced by 34%). Neoadjuvant, adjuvant, and palliative patients were all affected, mostly at the start of lockdown. On-site chemotherapy and supportive treatments fell by 39% compared to 2019, mainly due to fewer number of bone-modifying agents. Towards the end of 8 week period, treatment numbers had nearly returned to normal. The system adapted by modifying treatment regimens, using telemedicine, increased use of supportive medications and less frequent blood tests. Conclusion: COVID-19’s global impact has significantly reduced breast cancer treatments given during the first lockdown. Whilst recovery is now evident, cancer services, patients, and clinical cancer research must be prioritised in future waves.

Neutrophils (Ns) influence cancer cell survival and metastasis through the release of chemokines, cytokines and interactions within the microenvironment and at distal sites from the primary tumour. Background: Patients with Breast Cancer (BC) often display elevated levels of circulating blood neutrophils and an elevated neutrophil: lymphocyte ratio (NLR) is associated with a shorter disease-free survival in patients with Early Breast Cancer (EBC). Evidence from mouse models of BC shows that Ns can either have a tumour-promoting or tumour-inhibitory role. CD62L (L-selectin) is a cell adhesion molecule found on the surface of leukocytes which is important for helping circulatory Ns bind to the endothelium and migrate into tissues and is rapidly shed upon N activation. Our laboratory has found a lower proportion of Ns expressing CD62L in pre-clinical models of BC, which implies that Ns from tumour-bearing mice have less endothelial- adhesive capacity and hence will remain in the circulation for a longer time. However, there is limited knowledge regarding whether different N subpopulations are present within the circulation of patients with BC, how early this occurs in the disease process and whether this is influenced by BC phenotype. In order to address these questions, we phenotyped Ns from BC patients. Objectives: Our primary objectives were to investigate changes in the surface marker CD62L expression via flow cytometry in neutrophils from patients and HVs to see if the changes seen in the pre-clinical mouse models were also seen in patients. Since kinases govern many aspects of intracellular signalling and functions, we also assessed the Serine Threonine Kinase (STK) and Phosphotyrosine Kinase (PK) activity within circulatory neutrophils in patients with Breast Cancer and paired HVs using a Pamgene kinase assay. This evaluated the activity of kinases (n = 340 kinases) in N lysates to compare N kinase activity in EBC patients and age-matched HVs. Methods: We recruited 28 patients with Early BC (EBC) (10 Node +, 18 node -; 10 T1 and 16 T2 and 2 T3) and paired healthy volunteers (HVs) who were age and sex-matched to compare phenotypical features of Ns isolated from the blood. 21 Patients with Oestrogen receptor positive (ER+) and 7 with Oestrogen receptor negative (ER -) EBC were recruited between June 2018 and June 2021. No patient had overt metastatic disease and all were screened for exclusion factors, such as infection, autoimmune conditions and certain medication known to influence neutrophils. Results: We found that ER+ patients had a lower level of the CD62Llow neutrophil subset compared to HVs (P< 0.0375). In contrast there was a significant increase in the CD62Llow neutrophil subset (2-fold higher) for ER - patients compared to HVs (P< 0.0316).The Pamgene kinase assay showed that there was a general upregulation in both STK and PK kinase activity, especially the tyrosine family of kinases for patients with ER positive breast cancer (Median kinase score which is the combined sensitivity score and specificity score > 1.2) and a general downregulation in kinase activity, especially the CMGC family of kinases for patients with ER negative disease (Median kinase score > 1.2) compared to paired HVs. The functional implications of these differences in kinase activity are being actively investigated. Conclusion: We have detected changes in CD62L expression and neutrophil kinase activity within the circulation of patients with EBC and the nature of these changes appear to be intrinsically linked to ER subtype. These findings may have important implications for use as part of an early diagnostic multi-omic platform. Citation Format: Anisha Ramessur, Bana Ambasager, Ilaria Malanchi, Raoul Charles Coombes. The multi switching activity of neutrophils in the circulation of patients with early breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-01-14.

The peri‐operative use of angiotensin‐converting enzyme inhibitors or angiotensin‐2 receptor blockers is thought to be associated with an increased risk of postoperative acute kidney injury. To reduce this risk, these agents are commonly withheld during the peri‐operative period. This study aimed to investigate if withholding angiotensin‐converting enzyme inhibitors or angiotensin‐2 receptor blockers peri‐operatively reduces the risk of acute kidney injury following major non‐cardiac surgery. Patients undergoing elective major surgery on the gastrointestinal tract and/or the liver were eligible for inclusion in this prospective study. The primary outcome was the development of acute kidney injury within seven days of operation. Adjusted multi‐level models were used to account for centre‐level effects and propensity score matching was used to reduce the effects of selection bias between treatment groups. A total of 949 patients were included from 160 centres across the UK and Republic of Ireland. From this population, 573 (60.4%) patients had their angiotensin‐converting enzyme inhibitors or angiotensin‐2 receptor blockers withheld during the peri‐operative period. One hundred and seventy‐five (18.4%) patients developed acute kidney injury; there was no difference in the incidence of acute kidney injury between patients who had their angiotensin‐converting enzyme inhibitors or angiotensin‐2 receptor blockers continued or withheld (107 (18.7%) vs. 68 (18.1%), respectively; p = 0.914). Following propensity matching, withholding angiotensin‐converting enzyme inhibitors or angiotensin‐2 receptor blockers did not demonstrate a protective effect against the development of postoperative acute kidney injury (OR (95%CI) 0.89 (0.58–1.34); p = 0.567).

Background Randomized trials of radiotherapy and surgery for early breast cancer may have been too small to detect differences in long-term survival and recurrence reliably. We therefore performed a systematic overview (meta-analysis) of the results of such trials. Methods Information was sought on each subject from investigators who conducted trials that began before 1985 and that compared local therapies for early breast cancer. Data on mortality were available from 36 trials comparing radiotherapy plus surgery with the same type of surgery alone, 10 comparing more-extensive surgery with less-extensive surgery, and 18 comparing more-extensive surgery with less-extensive surgery plus radiotherapy. Information on mortality was available for 28,405 women (97.4 percent of the 29,175 women in the trials). Results The addition of radiotherapy to surgery resulted in a rate of local recurrence that was three times lower than the rate with surgery alone, but there was no significant difference in 10-year survival; among a total of 17,273 women enrolled in such trials, mortality was 40.3 percent with radiotherapy and 41.4 percent without radiotherapy (P = 0.3). Radiotherapy was associated with a reduced risk of death due to breast cancer (odds ratio, 0.94; 95 percent confidence interval, 0.88 to 1.00; P = 0.03), which indicates that, after 10 years, there would be about 0 to 5 fewer deaths due to breast cancer per 100 women. However, there was an increased risk of death from other causes (odds ratio, 1.24; 95 percent confidence interval, 1.09 to 1.42; P = 0.002). This, together with the age-specific death rates, implies, after 10 years, a few extra deaths not due to breast cancer per 100 older women or per 1000 younger women. During the first decade or two after diagnosis, the excess in the rate of such deaths that was associated with radiotherapy was much greater among women who were over 60 years of age at randomization (15.3 percent vs. 11.1 percent [339 vs. 249 deaths]) than among those under 50 (2.5 percent vs. 2.0 percent [62 vs. 49 deaths]). Breast-conserving surgery involved some risk of recurrence in the remaining tissue, but no significant differences in overall survival at 10 years were found in the studies of mastectomy versus breast-conserving surgery plus radiotherapy (4891 women), more-extensive surgery versus less-extensive surgery (4818 women), or axillary clearance versus radiotherapy as adjuncts to mastectomy (4370 women). Conclusions Some of the local therapies for breast cancer had substantially different effects on the rates of local recurrence — such as the reduced recurrence with the addition of radiotherapy to surgery — but there were no definite differences in overall survival at 10 years.

Background There have been many randomised trials of adjuvant tamoxifen among women with early breast cancer, and an updated overview of their results is presented. Methods In 1995, information was sought on each woman in any randomised trial that began before 1990 of adjuvant tamoxifen versus no tamoxifen before recurrence. Information was obtained and analysed centrally on each of 37 000 women in 55 such trials, comprising about 87% of the worldwide evidence. Compared with the previous such overview, this approximately doubles the amount of evidence from trials of about 5 years of tamoxifen and, taking all trials together, on events occurring more than 5 years after randomisation. Findings Nearly 8000 of the women had a low, or zero, level of the oestrogen-receptor protein (ER) measured in their primary tumour. Among them, the overall effects of tamoxifen appeared to be small, and subsequent analyses of recurrence and total mortality are restricted to the remaining women (18 000 with ER-positive tumours, plus nearly 12 000 more with untested tumours, of which an estimated 8000 would have been ER-positive). For trials of 1 year, 2 years, and about 5 years of adjuvant tamoxifen, the proportional recurrence reductions produced among these 30 000 women during about 10 years of follow-up were 21% (SD 3), 29% (SD 2), and 47% (SD 3), respectively, with a highly significant trend towards greater effect with longer treatment (χ21=52·0, 2p Interpretation For women with tumours that have been reliably shown to be ER-negative, adjuvant tamoxifen remains a matter for research. However, some years of adjuvant tamoxifen treatment substantially improves the 10-year survival of women with ER-positive tumours and of women whose tumours are of unknown ER status, with the proportional reductions in breast cancer recurrence and in mortality appearing to be largely unaffected by other patient characteristics or treatments.

CDK7 inhibition has emerged as a promising strategy in a range of cancer indications. CDK7 acts as a regulator of transcription through its role in phosphorylating and activating RNA Polymerase II (polII) as well as a master regulator of the cell cycle through phosphorylation of members of the CDK family. Inhibition of CDK7 in cancer cells has been shown to be effective in blocking transcriptional addiction to a defined cluster of genes (Wang et al 2015) and leads to decreased cell cycling, a decrease in the levels of proto-oncogenes such as c-Myc and induction of apoptosis. Here we describe the properties of a potent, selective and orally bioavailable CDK7 inhibitor CT7001 (formerly known as ICEC0942). Profiling across a pan-cancer cell line panel showed that CT7001 has anti-proliferative activity in a range of cancer types including acute myeloid leukaemia (AML), small cell lung (SCL) and hormone sensitive and triple negative breast cancers (TNBC).Mechanistic investigations revealed that CT7001s activity was associated with both a decrease in cell proliferation and an induction of apoptosis. Inhibition of cell proliferation was commensurate with a decrease in the levels of c-Myc, Mcl-1 and phospho-Pol II as determined by Western Blot analysis.CT7001 was then evaluated in a range of pre-clinical cancer models. CT7001 was shown to lead to cell death in a panel of patient derived models of small-cell lung cancer (SCLC) in 3D spheroid assays. In an in vivo orthotopic-patient derived xenograft model of TNBC in nu/nu mice, orally administered CT7001 monotherapy produced strong and sustained regression of the tumour that persisted during the dosing schedule, and strong suppression was still maintained upon cessation of treatment. At doses that produced regression CT7001 was well tolerated with little effect on body weight ( Citation Format: Edward K. Ainscow, Andrew Leishman, Elaine Sullivan, Bo Li, William Gallagher, Adam Peall, Kristopher Clark, Stuart Thomson, Simak Ali, Raoul C. Coombes, Ash Bahl. CT7001: An orally bioavailable CDK7 inhibitor is a potential therapy for breast, small-cell lung and haematological cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4834.

MicroRNA (miR)-106b~25 cluster regulates bypass of doxorubicin and γ-radiation induced senescence by downregulation of the E-cadherin transcriptional activator EP300. We asked whether upregulation of miR-106~25 cluster generates cells with a truly multidrug resistant (MDR) phenotype and whether this is due to upregulation of the ATP-binding cassette (ABC) transporter P-glycoprotein. We used minimally transformed mammary epithelial breast cancer cells (MTMECs) in which the miR-106b~25 cluster was experimentally upregulated by lentiviral transfection or in which hairpins targeting either EP300 or E-cadherin mRNAs have been expressed with lentiviruses. We find that overexpression of miR-106b~25 cluster led to the generation of MDR MTMECs (resistant to etoposide, colchicine and paclitaxel). Paclitaxel resistance was also studied after experimental downregulation of EP300 or E-cadherin. However none of these cells overexpressed P-glycoprotein or where able to efflux a fluorescent derivative of paclitaxel, making this phenotype drug-transporter independent. Paclitaxel treatment in MTMECs led to an increase in early apoptotic cells (Annexin V-positive), activation of caspase-9 and increase in the proportion of cells at the G2/M phase of the cell cycle. However, MTMEC overexpressing miR-106b~25 cluster, or with EP300 or E-cadherin downregulated, showed less activation of apoptosis, caspase-9 and caspase-3/-7 activities. Thus, miR-106b~25 cluster controls transporter-independent MDR by apoptosis evasion via downregulation of EP300.

Background: [18F]ICMT-11 is an isatin analogue which has been developed by our group as a novel PET radiotracer for studies of apoptosis in vivo. Preclinical studies have demonstrated subnanomolar affinity to caspase 3, and validated the potential for imaging apoptosis in xenograft models. A first-in-man study showed that the agent was well tolerated with acceptable dosimetry. This is the first study of this agent to measure the effect of chemotherapy on radiotracer uptake in patients. As apoptosis is a dynamic process, one of the main objectives of the study was to determine the optimal time-point for imaging post-chemotherapy and compare the results with immunohistochemistry assessments at the same time-points. The study was approved by a regional ethics committee and ARSAC. Methods: 7 patients with breast tumour lesions measuring 15mm or more, due to undergo neoadjuvant chemotherapy with FEC (5FU, Epirubicin, Cyclophosphamide) had dynamic PET scans for 66mins 30seconds following intravenous injection of [18F]ICMT-11 with a mean activity of 340.82 Mbq±20.76 and Specific Activity range of 447.014-5128.34 Gbq/µmol prior to chemotherapy and 24h-2 weeks post-chemotherapy. A breast biopsy was also obtained within a few hours of the 2nd PET scan to correlate apoptosis in the breast tissue utilising TUNEL and Caspase 3 staining by immunohistochemistry. Volumes of interest were drawn manually and analyzed using Analyze software®. Results: The scans were well tolerated in all patients. Uptake of [18F]ICMT-11 was demonstrated in all tumor lesions. The tumours studied included ER positive and PR positive, HER2 positive and triple negative patients. The first cohort patients were imaged pre-chemotherapy and 24-48h post chemotherapy. Tumour to Breast ratio (TBR) showed an increase from 1.42±0.21(pre) to 1.71±0.33 (post). Tumour to muscle ratio (TMR) was not increased, 1.52±0.30(pre) and 1.22±0.09 (post). In addition, an increase the SUV was noted in the lymph nodes of patients, at both 24 and 48h. (SUVav 0.39±0.02 (pre), 0.45±0.03 (post), and SUVmax 0.87± 0.02(pre) ,1.22±0.12 (post). The lymph nodes were however not sampled for immunohistochemistry. A further cohort of patients had the follow-up scan 2 weeks post chemotherapy, TBR and TMR were both increased in this cohort 1.50±0.22 (pre), 2.52±0.48 (post),and 1.82±0.10 (pre), 2.08±0.0.04 (post), respectively. Caspase and TUNEL labelling with immunohistochemistry also showed increased in apoptosis in the breast biopsies at 2 weeks compared to baseline in keeping with the PET data. Conclusion: These preliminary data suggest that [18F]ICMT-11 is a promising marker for chemotherapy induced apoptosis in vivo, and correlates with findings in tumor biospsies using TUNEL and immunostaining for caspase 3. Further work is underway to study a larger cohort of patients, and identify the optimal PET pharmacokinetic parameter to describe [18F]ICMT-11 uptake and retention. Citation Format: Shairoz Merchant, Eric O Aboagye, Adrian Lim, Kasia Kozlowski, Naina Patel, Jennifer Steel, Susan Cleator, Sami Shousha, Vidhya Varghese, Raoul C Coombes, Laura Kenny. Evaluation of apoptosis in breast cancer using the novel PET probe [18F]ICMT-11 in patients treated with neoadjuvant FEC chemotherapy: Initial assessment of optimum imaging time and relation to caspase-3 immunostaining [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-01-02.