Combining systemic therapies with radiation in breast cancer

The integration of radiotherapy with systemic therapy in advanced triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with high aggressiveness and poor prognosis. For patients who have undergone multiple treatments, systemic drug therapy often presents challenges with limited efficacy and significant side effects. Radiotherapy, a pivotal local treatment, has shown substantial local control benefits in patients with inoperable locally advanced or metastatic disease. Clinical evidence suggests that integrating systemic therapy with locoregional radiotherapy can confer survival advantages in advanced malignancies. Within multidisciplinary treatment, the synergy between radiotherapy and systemic therapies shows promise for enhancing outcomes and extending survival. This review synthesizes recent advances in combining radiotherapy and systemic therapy in managing advanced TNBC, focusing on preclinical and clinical evidence regarding efficacy and safety. By reviewing these advancements, we aim to identify novel therapeutic strategies and integrate clinical evidence to inform best practices in TNBC management, ultimately improving patient outcomes.

Radiation therapy in the thoracic region: Radio-induced cardiovascular disease, cardiac delineation and sparing, cardiac dose constraints, and cardiac implantable electronic devices

Radiation therapy in the thoracic region may deliver incidental ionizing radiation to the surrounding healthy structures, including the heart. Radio-induced heart toxicity has long been a concern in breast cancer and Hodgkin's lymphoma and was deemed a long-term event. However, recent data highlight the need to limit the dose to the heart in less favorable thoracic cancers too, such as lung and esophageal cancers in which incidental irradiation led to increased mortality. This article will summarize available cardiac dose constraints in various clinical settings and the types of radio-induced cardiovascular diseases encountered as well as delineation of cardiac subheadings and management of cardiac devices. Although still not completely deciphered, heart dose constraints remain intensively investigated and the mean dose to the heart is no longer the only dosimetric parameter to consider since the left anterior descending artery as well as the left ventricle should also be part of dosimetry constraints.

CONcurrent ChEmotherapy and RadioTherapy in adjuvant treatment of breast cancer (CONCERT): a phase 2 study

Purpose

This phase 2 study evaluated the safety of adjuvant chemoradiation (CTRT) for breast cancer.

Methods

From April 2019 to 2020, 60 patients with stage II-III invasive breast cancer planned for adjuvant taxane-based chemotherapy and radiotherapy (RT) were accrued. Local ± regional (excluding the internal mammary nodal region) RT (40 Gy in 15 fractions ± boost) was started with the third cycle of an adjuvant taxane in a 3-weekly schedule or with the eighth cycle in a weekly schedule.

Results

Thirty-six patients received 3-weekly paclitaxel regimen and 24 received weekly paclitaxel regimen. The commonly used technique was three-dimensional conformal RT which was employed in 58% of patients. Regional RT, including the medial supraclavicular region, was done in 42 patients (70%). No dose-limiting (grade 3 or 4) toxicity was documented and all patients completed CTRT without any treatment interruption. The median ejection fraction pre and post CTRT 6 months was 60% (p = 0.177). The median value of cardiac enzyme (Troponin T ng/L) decreased from 37 to 20 (p = 0.009) post CTRT 6 months. Of the 54 patients who underwent the pulmonary function tests, there was no significant difference in various parameters like functional vital capacity (FVC) (2.29 versus 2.2 L, p = 0.375), forced expiratory volume at 1 second (FEV1) (1.86; 1.82; p = 0.365), FEV1/FVC (81.5; 81.43; p = 0.9) and diffusion lung capacity for carbon monoxide (88.3; 87.6; p = 0.62). At a median follow-up of 34 months, the 3-year actuarial rate of disease-free survival and overall survival was 75% and 98.3%, respectively. Quality of life scores (QOL) improved after treatment for most of the domains comparable to the pre-RT scores.

Conclusion

Taxane-based adjuvant CTRT is a safe option and results in minimal toxicity and excellent compliance. It has favourable impact on cardio-pulmonary profile and QOL scores.

Paclitaxel-loaded tumor cell-derived microparticles improve radiotherapy efficacy in triple-negative breast cancer by enhancing cell killing and stimulating immunity

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor characterized by high recurrence and metastasis, with a very poor prognosis, and there are still great challenges in its clinical treatment. Here, we describe the development of a novel modality for the treatment of TNBC with tumor cell-derived microparticles loaded with paclitaxel (MP-PTX) in combination with radiotherapy. We show that MP can deliver agents to tumor cells by homologous targeting, thereby increasing the absorption rate of the chemotherapeutic agent and enhancing its killing effects on tumor cells. We further demonstrate that MP-PTX combined with radiotherapy shows a synergistic antitumor effect by enhancing the inhibition of tumor cell proliferation, promoting tumor cell apoptosis, reducing the immunosuppressive microenvironment at the tumor site, and activating the antitumor immune response. Altogether, this study provides a referable and optional method for the clinical treatment of refractory tumors such as TNBC based on the combination of T-MP-delivered chemotherapeutic drugs and radiotherapy. Chemical compounds: paclitaxel (PTX), paclitaxel-loaded tumor cell-derived microparticles (MP-PTX).

Synergistic enhancement of cell death by triple combination therapy of docetaxel, ultrasound and microbubbles, and radiotherapy on PC3 a prostate cancer cell line

The application of ultrasound and microbubbles (USMB) has been shown to enhance both chemotherapy and radiotherapy. This study investigated the potential of triple combination therapy comprised of USMB, docetaxel (Taxotere: TXT) chemotherapy and XRT to enhance treatment efficacy. Prostate cancer (PC3) cells in suspension were treated with various combinations of USMB, chemotherapy and radiotherapy. Cells were treated with ultrasound and microbubbles (500 kHz pulse center frequency, 580 kPa peak negative pressure, 10 μs pulse duration, 60 s insonation time and 2% Definity microbubbles (v/v)), XRT (2 Gy), and Taxotere (TXT) at concentrations ranging from 0.001 to 0.1 nM for 5- and 120-minutes duration. Following treatment, cell viability was assessed using a clonogenic assay. Therapeutic efficiency of the combined treatments depended on chemotherapy and microbubble exposure conditions. Under the exposure conditions of the study, the triple combination therapy synergistically enhanced clonogenic cell death compared to single and double combination therapy. Cell viability of ∼2% was achieved with the triple combination therapy corresponding to ∼29, ∼37, and ∼38 folds decrease compared to XRT (57%), USMB (74%) and TXT (76%) alone conditions, respectively. In addition, the triple combination therapy decreased cell viability by ∼29, ∼19- and ∼11 folds compared to TXT_2hr + USMB (58%), TXT_2hr + XRT (37%), and USMB + XRT (22%), respectively. The in vivo PC3 tumours showed that USMB significantly enhanced cell death through detection of apoptosis (TUNEL) with both TXT and TXT + XRT. The study demonstrated that the triple combination therapy can significantly enhance cell death in prostate cancer cells both in vitro and in vivo under relatively low chemotherapy and ionizing radiation doses.

Radiotherapy of Breast Cancer-Professional Guideline 1st Central-Eastern European Professional Consensus Statement on Breast Cancer

The international radiotherapy (RT) expert panel has revised and updated the RT guidelines that were accepted in 2020 at the 4th Hungarian Breast Cancer Consensus Conference, based on new scientific evidence. Radiotherapy after breast-conserving surgery (BCS) is indicated in ductal carcinoma in situ (stage 0), as RT decreases the risk of local recurrence (LR) by 50-60%. In early stage (stage I-II) invasive breast cancer RT remains a standard treatment following BCS. However, in elderly (≥70 years) patients with stage I, hormone receptor-positive tumour, hormonal therapy without RT can be considered. Hypofractionated whole breast irradiation (WBI) and for selected cases accelerated partial breast irradiation are validated treatment alternatives to conventional WBI administered for 5 weeks. Following mastectomy, RT significantly decreases the risk of LR and improves overall survival of patients who have 1 to 3 or ≥4 positive axillary lymph nodes. In selected cases of patients with 1 to 2 positive sentinel lymph nodes axillary dissection can be substituted with axillary RT. After neoadjuvant systemic treatment (NST) followed by BCS, WBI is mandatory, while after NST followed by mastectomy, locoregional RT should be given in cases of initial stage III-IV and ypN1 axillary status.

Studies on DNA Damage Repair and Precision Radiotherapy for Breast Cancer

Radiotherapy acts as an important component of breast cancer management, which significantly decreases local recurrence in patients treated with conservative surgery or with radical mastectomy. On the foundation of technological innovation of radiotherapy setting, precision radiotherapy of cancer has been widely applied in recent years. DNA damage and its repair mechanism are the vital factors which lead to the formation of tumor. Moreover, the status of DNA damage repair in cancer cells has been shown to influence patient response to the therapy, including radiotherapy. Some genes can affect the radiosensitivity of tumor cell by regulating the DNA damage repair pathway. This chapter will describe the potential application of DNA damage repair in precision radiotherapy of breast cancer.

The effects of combined treatment with ionizing radiation and indocyanine green-mediated photodynamic therapy on breast cancer cells

This study was undertaken to evaluate the effects of indocyanine green as a sensitizer in both photodynamic and radiation therapy on MCF-7 human breast cancer cells line. The cells were incubated with indocyanine green at different concentrations for 24h and were then exposed in the independent treatment groups to a non-coherent light at different fluence rates and X-ray ionizing radiation at different dose rates. In addition, combination effects of this chemo, photo, and radiotherapy were evaluated. The percentage of the cell survival was investigated using the MTT assay. The results showed that indocyanine green had no significant cytotoxic effects up to 100 μM but as a photosensitizer had a strong cytotoxic effect on cancer cells. Despite, indocyanine green could not act as a radiosensitizer. Furthermore, it is surprising to find that 50 μM of indocyanine green in combination with light at 60 J/cm(2) and 4 Gy of X-ray radiation astonishingly killed cancer cells and reduced the percentage of viable cancer cells to be 3.42%. According to the findings, we observed the same efficacy of treatment by adding a low dose of radiation and reducing light fluence rate. In fact, it appears from our data that the adverse effects of photodynamic therapy can be partially abated without reducing the efficacy of treatment. Obviously, this new therapeutic avenue in breast cancer therapy could be worth further investigation and elucidation and should be tested in vivo models for being applied in human therapy.

Thalidomide and irradiation combination therapy increases substance P levels in vitro

Thalidomide is an anti-angiogenic agent that is used in the treatment of cancer. However, in many cases, particularly in patients with breast cancer, thalidomide treatment alone is insufficient and must be combined with other drugs or therapies. In the clinical setting, thalidomide is most commonly used in combination with radiation therapy. However, the exact mechanisms of its effect are unkown. Radiotherapy alters the expression of substance P, which is considered a crucial pro-angiogenic peptide. To determine whether thalidomide and radiotherapy in combination overcome the limitations of each as monotherapy, we examined the effects of the combination on the growth of breast cancer cells as well as on the expression of substance P in vitro. Mouse breast cancer cells (4T1) and cells produced from metastatic lesions (4THMpc) were treated with radiotherapy (RT) (45 Gy) alone, thalidomide (Thal) (40 μg/ml) alone or combination therapy (40 μg/ml Thal + 45 Gy RT), and compared with control cells. MTS, Live/Dead and trypan blue exclusion assays were used to evaluate the cytotoxic effects of the treatments. The levels of substance P in the conditioned media and in the cell lysates were determined by a substance P ELISA kit, and changes in the protein content were analyzed by Western blotting. Thalidomide alone resulted in a significant inhibition in the growth of the 4T1 (34.1%) and 4THMpc (52.6%) cell lines. RT alone inhibited the growth of the 4T1 (19.2%) and 4THMpc (23.31%) cell lines. The combination therapy enhanced the growth inhibition noted in the 4T1 (47.9%) and 4THMpc (62.03%) cell lines. The expression of substance P in the conditioned media and in the cell lysates increased within 72 h of RT. This increase was significantly enhanced with the combination therapy. These data indicate that thalidomide inhibits breast cancer cell growth and potentiates the anti-tumor effects of radiation at appropriate doses.

Optimal sequence of implied modalities in the adjuvant setting of breast cancer treatment: an update on issues to consider

The adjuvant setting of early breast cancer treatment is an evolving field where different modalities must be combined to improve outcomes; moreover, quality of life of breast cancer survivors emerges as a new important parameter to consider, thus implying a better understanding of toxicities of these modalities. We have conducted a review focusing on the latest literature of the past 3 years, trying to evaluate the existing data on the maximum acceptable delay of radiotherapy when given as sole adjuvant treatment after surgery and the optimal sequence of all these modalities with respect to each other. It becomes evident radiotherapy should be given as soon as possible and within a time frame of 6-20 weeks. Chemotherapy is given before radiotherapy and hormone therapy. However, radiotherapy should be started within 7 months after surgery in these cases. Hormone therapy with tamoxifen might be given safely concomitantly or sequentially with radiotherapy although solid data are still lacking. The concurrent administration of letrozole and radiotherapy seems to be safe, whereas data on trastuzumab can imply only that it is safe to use concurrently with radiotherapy. Randomized comparisons of hormone therapy and trastuzumab administration with radiotherapy need to be performed.