Role of the Combination of Cyclin-Dependent Kinase Inhibitors (CDKI) and Radiotherapy (RT) in the Treatment of Metastatic Breast Cancer (MBC): Advantages and Risks in Clinical Practice

Advances in molecular targeted therapies to increase efficacy of (chemo)radiation therapy

Recent advances in understanding the tumor's biology in line with a constantly growing number of innovative technologies have prompted characterization of patients' individual malignancies and may display a prerequisite to treat cancer at its patient individual tumor vulnerability. In recent decades, radiation- induced signaling and tumor promoting local events for radiation sensitization were explored in detail, resulting the development of novel molecular targets. A multitude of pharmacological, genetic, and immunological principles, including small molecule- and antibody-based targeted strategies, have been developed that are suitable for combined concepts with radiation (RT) or chemoradiation therapy (CRT). Despite a plethora of promising experimental and preclinical findings, however, so far, only a very limited number of clinical trials have demonstrated a better outcome and/or patient benefit when RT or CRT are combined with targeted agents. The current review aims to summarize recent progress in molecular therapies targeting oncogenic drivers, DNA damage and cell cycle response, apoptosis signaling pathways, cell adhesion molecules, hypoxia, and the tumor microenvironment to impact therapy refractoriness and to boost radiation response. In addition, we will discuss recent advances in nanotechnology, e.g., RNA technologies and protein-degrading proteolysis-targeting chimeras (PROTACs) that may open new and innovative ways to benefit from molecular-targeted therapy approaches with improved efficacy.

The Impact of Deep Inspiration Breath Hold (DIBH) Implementation on the Hybrid Technique in Left-Sided Whole Breast Irradiation: A Dosimetric Characteristic Study of 3D-CRT Hybrid VMAT in DIBH and Free Breathing Conditions, and VMAT in Free Breathing Conditions

Aim

To investigate the impact of DIBH for heart sparing effect on left sided breast postoperative whole breast irradiation by comparing the dosimetric characteristics of 3D-CRT hybrid VMAT and pure VMAT treatment planning under DIBH condition.

Materials and Methods

The primary CT data sets from previously treated left sided early breast cancer were used for pure volumetric arc therapy (VMAT) technique re-planning for the dosimetric characteristics comparison. A treatment plan of 3D-CRT hybrid VMAT technique was re-planned on the free breath (FB) condition for the investigation of the dosimetric characteristics comparison on DIBH condition. The prescribed dose for all the treatment plans was 42.5Gy in 16 fractions. All plans were optimized to cover 100% of the PTV by 95% of prescribed dose. The dosimetric differences among the 3 treatment plans for the 20 patients were analyzed using Wilcoxon signed-rank test, with p value<0.05 considered statistically significant.

Results

3D-CRT hybrid VMAT using DIBH technique yielded the best results on the conformity index (CI) and homogeneity index (HI). By comparing this 3D-CRT hybrid VMAT technique using FB and DIBH technique, the mean heart dose (MHD) was reduced from 5.38Gy to 1.65Gy, respectively (p =0.001) and the left anterior descending coronary artery (LAD)0.03cc dose was reduced from 27.87Gy to 9.41Gy, respectively (p =0.001). 3D-CRT hybrid VMAT using DIBH technique significantly reduced the V5, V20 and D mean of the ipsilateral lung and D mean of the contralateral lung. The D5 of right breast was significantly reduced by 3D-CRT hybrid VMAT compared with VMAT using DIBH technique.

Conclusion

The incorporation of DIBH into 3D-CRT hybrid VMAT technique provides the best benefits for the heart and the OAR with respect to the radiation dose-sparing effect without compromising the target conformity and homogeneity in the treatment planning.

Dermatologic toxicities to inhibitors of cyclin-dependent kinases CDK 4 and 6: An updated review for clinical practice

Cyclin-dependent kinase (CDK) 4/6 inhibitors (palbociclib, ribociclib and abemaciclib) have revolutionized the treatment of metastatic breast carcinoma. They currently form the first-line treatment, in combination with endocrine agents, for the management of locally advanced or metastatic hormone receptor-positive (HR + ), human epidermal growth factor receptor 2-negative (HER2-) breast cancer, the largest subtype of breast carcinoma. CDK 4/6 inhibitors have shown comparable efficacy outcomes with predictable and manageable adverse events. In this setting, dermatologic toxicity appears to be relatively frequent, accounting for up to 15% of all reported adverse events. It is usually mild to moderate in intensity and does not normally constitute a dose-limiting toxicity. The range of dermatologic adverse events includes both non-specific entities (maculopapular rash, pruritus, alopecia) and more characteristic toxicities related to CDK4/6 inhibitors, such as vitiligo-like lesions or cutaneous lupus erythematosus. Finally, more severe or life-threatening skin reactions can occasionally occur. The main dermatologic manifestations associated with CDK4/6 inhibitors, as well as management thereof, are described in this comprehensive review.

Considerations on surgery invasiveness and response and toxicity patterns in classic palliative radiotherapy for acrometastases of the hand: a hint for a potential role of stereotactic body radiation therapy? A case report and literature review

Background

The rarity of hand acrometastases hampers the consensus-building for their optimal management among the involved oncology professionals. In the current literature, demolitive surgery overcomes the use of palliative radiotherapy, which proved to be ineffective in more than 30% of cases treated with classic palliative dose schemes, carrying also a not negligible radiation-related adverse event rate. Against this background, stereotactic body radiation therapy (SBRT) could emerge as a well-balanced therapeutic option.

Case summary

Here we describe the methods and outcomes of a SBRT treatment of a painful and function-limiting hand acrometastasis in a patient with a history of stage IIIB lung adenocarcinoma. We delivered a total dose of 30 Gy in five daily fractions to a soft-tissue metastasis abutting the fifth metacarpal bone through the SBRT protocol generally used for intracranial treatments. A few weeks later, the patient reported a clinical complete response with acrometastasis and pain disappearance, function recovery, and no significant toxicity. The acrometastasis was the first sign of an atypical cancer progression.

Conclusions

SBRT for hand acrometastases is feasible and might have the best therapeutic profile among the currently available treatment options for this rare clinical scenario. Larger investigations are needed to confirm the present single-case experience.

Clinical Outcomes of Stereotactic Radiosurgery-Related Radiation Necrosis in Patients with Intracranial Metastasis from Melanoma

Background:

Radiation necrosis (RN) is a clinically relevant complication of stereotactic radiosurgery (SRS) for intracranial metastasis (ICM) treatments. Radiation necrosis development is variable following SRS. It remains unclear if risk factors for and clinical outcomes following RN may be different for melanoma patients. We reviewed patients with ICM from metastatic melanoma to understand the potential impact of RN in this patient population.

Methods:

Patients who received SRS for ICM from melanoma at Mayo Clinic Arizona between 2013 and 2018 were retrospectively reviewed. Data collected included demographics, tumor characteristics, radiation parameters, prior surgical and systemic treatments, and patient outcomes. Radiation necrosis was diagnosed by clinical evaluation including brain magnetic resonance imaging (MRI) and, in some cases, tissue evaluation.

Results:

Radiation necrosis was diagnosed in 7 (27%) of 26 patients at 1.6 to 38 months following initial SRS. Almost 92% of all patients received systemic therapy and 35% had surgical resection prior to SRS. Patients with RN trended toward having larger ICM and a prior history of surgical resection, although statistical significance was not reached. Among patients with resection, those who developed RN had a longer period between surgery and SRS start (mean 44 vs 33 days). Clinical improvement following treatment for RN was noted in 2 (29%) patients.

Conclusions:

Radiation necrosis is relatively common following SRS for treatment of ICM from metastatic melanoma and clinical outcomes are poor. Further studies aimed at mitigating RN development and identifying novel approaches for treatment are warranted.

Effect of EGFR-TKIs combined with craniocerebral radiotherapy on the prognosis of EGFR-mutant lung adenocarcinoma patients with brain metastasis: A propensity-score matched analysis

Background and Purpose

Epidermal growth factor receptor (EGFR)-mutant lung cancers are associated with a high risk of developing brain metastases (BM). Craniocerebral radiotherapy is a cornerstone for the treatment of BM, and EGFR-TKIs act on craniocerebral metastases". However, whether EGFR-TKIs combined with craniocerebral radiotherapy can further increase the efficacy and improve the prognosis of patients is unclear. This study aimed to evaluate the difference in efficacy between targeted-therapy alone and targeted-therapy combined with radiotherapy in EGFR-mutant lung adenocarcinoma patients with BM.

Materials and Methods

A total of 291 patients with advanced non-small cell lung cancer (NSCLC) and EGFR mutations were enrolled in this retrospective cohort study. Propensity score matching (PSM) was conducted using a nearest-neighbor algorithm (1:1) to adjust for demographic and clinical covariates. Patients were divided into two groups: EGFR-TKIs alone and EGFR-TKIs combined with craniocerebral radiotherapy. Intracranial progression-free survival (iPFS) and overall survival (OS) were calculated. Kaplan-Meier analysis was used to compare iPFS and OS between the two groups. Brain radiotherapy included WBRT, local radiotherapy, and WBRT+Boost.

Results

The median age at diagnosis was 54 years (range: 28-81 years). Most patients were female (55.9%) and non-smokers (75.5%). Fifty-one pairs of patients were matched using PSM. The median iPFS for EGFR-TKIs alone (n=37) and EGFR-TKIs+craniocerebral radiotherapy (n=24) was 8.9 and 14.7 months, respectively. The median OS for EGFR-TKIs alone (n=52) and EGFR-TKIs+craniocerebral radiotherapy (n=52) was 32.1 and 45.3 months, respectively.

Conclusion

In EGFR-mutant lung adenocarcinoma patients with BM, targeted therapy combined with craniocerebral radiotherapy is an optimal treatment.

The correlations between psychological distress, cognitive impairment and quality of life in patients with brain metastases after whole-brain radiotherapy

BACKGROUND

Psychological distress and cognitive impairment are highly prevalent among patients with brain metastases after whole-brain radiotherapy (WBRT). Our purpose was to evaluate the correlations between psychological distress, cognitive impairment and quality of life in patients with brain metastases after WBRT.

METHODS

Seventy-one patients with brain metastasis treated with WBRT were enrolled in this study and were investigated with several scales, including the Montreal Cognitive Assessment Scale (MoCA), the Functional Assessment of Cancer Therapy-Cognitive Function version 3 (FACT-Cog, version 3), the Functional Assessment of Cancer Therapy-Brain Module version 4 (FACT-Br, version 4) and the Psychological Distress Thermometer (DT), before and after WBRT.

RESULTS

The MoCA, FACT-Cog and FACT-Br scores in patients with brain metastases were significantly decreased after WBRT compared with before WBRT (z = - 7.106, - 6.933 and - 6.250, respectively, P < 0.001), while the DT scores were significantly increased (z = 6.613, P < 0.001). There was an obvious negative correlation between the DT score and the FACT-Cog score (r = - 0.660, P < 0.001), a significant negative correlation between the DT score and the FACT-Br score (r = - 0.833, P < 0.001), and an obvious positive correlation between the FACT-Cog score and the FACT-Br score (r = 0.603, P < 0.001). These results suggest that WBRT can cause cognitive impairment in patients with brain metastases, increase their psychological distress and reduce their quality of life (QOL).

CONCLUSION

After receiving WBRT, the cognitive function and QOL of patients with brain metastases were decreased, while psychological distress increased. The cognitive impairment and the decline of QOL after WBRT are associated with increased psychological distress, and that the decline of QOL is associated with cognitive impairment of patients.

Dose Reduction to Motor Structures in Adjuvant Fractionated Stereotactic Radiotherapy of Brain Metastases: nTMS-Derived DTI-Based Motor Fiber Tracking in Treatment Planning

Background: Resection of brain metastases (BM) close to motor structures is challenging for treatment. Navigated transcranial magnetic stimulation (nTMS) motor mapping, combined with diffusion tensor imaging (DTI)-based fiber tracking (DTI-FTmot.TMS), is a valuable tool in neurosurgery to preserve motor function. This study aimed to assess the practicability of DTI-FTmot.TMS for local adjuvant radiotherapy (RT) planning of BM. Methods: Presurgically generated DTI-FTmot.TMS-based corticospinal tract (CST) reconstructions (FTmot.TMS) of 24 patients with 25 BM resected during later surgery were incorporated into the RT planning system. Completed fractionated stereotactic intensity-modulated RT (IMRT) plans were retrospectively analyzed and adapted to preserve FTmot.TMS. Results: In regular plans, mean dose (Dmean) of complete FTmot.TMS was 5.2 ± 2.4 Gy. Regarding planning risk volume (PRV-FTTMS) portions outside of the planning target volume (PTV) within the 17.5 Gy (50%) isodose line, the DTI-FTmot.TMS Dmean was significantly reduced by 33.0% (range, 5.9−57.6%) from 23.4 ± 3.3 Gy to 15.9 ± 4.7 Gy (p < 0.001). There was no significant decline in the effective treatment dose, with PTV Dmean 35.6 ± 0.9 Gy vs. 36.0 ± 1.2 Gy (p = 0.063) after adaption. Conclusions: The DTI-FTmot.TMS-based CST reconstructions could be implemented in adjuvant IMRT planning of BM. A significant dose reduction regarding motor structures within critical dose levels seems possible.

Radiotherapy and CDK inhibitors: Opportunities and risks

CDK4/6 inhibitors are nowadays commonly used in metastatic HR+/HER2- breast cancer. Herein, we report a literature review regarding the benefits and risks of their combination with radiotherapy. Numerous pre-clinical studies have indeed shown a potential synergistic effect of these treatments in combination with radiotherapy in various types of cancers. On the other hand, some retrospective clinical studies have reported increased acute toxicity in case of digestive or pulmonary irradiation; therefore, it is advisable to discontinue CDK4/6 inhibitors before starting irradiation. Several prospective clinical trials are currently ongoing to assess the feasibility of this combination.

A Critical Overview of Predictors of Heart Sparing by Deep-Inspiration-Breath-Hold Irradiation in Left-Sided Breast Cancer Patients

Simple Summary

Adjuvant radiotherapy could damage the heart in left-sided breast cancer patients. The deep-inspiration-breath-hold technique may limit the heart exposure to radiation. As non-beneficiaries exist, there is some need to do an upfront cost-effective selection. Some easy-to-use anatomical predictors may help insiders in the treatment decision. The awareness of such findings may improve the efficiency of practitioners’ workflows.

Abstract

Radiotherapy represents an essential part of the therapeutic algorithm for breast cancer patients after conservative surgery. The treatment of left-sided tumors has been associated with a non-negligible risk of developing late-onset cardiovascular disease. The cardiac risk perception has especially increased over the last years due to the prolongation of patients’ survival owing to the advent of new drugs and an ever earlier cancer detection through screening programs. Improvements in radiation delivery techniques could reduce the treatment-related heart toxicity. The deep-inspiration-breath-hold (DIBH) irradiation is one of the most advanced treatment approaches, which requires specific technical equipment and uses inspiration to displace the heart from the tangential radiation fields. However, not all patients benefit from its use. Moreover, DIBH irradiation needs patient compliance and accurate training. Therefore, such a technique may be unjustifiably cumbersome and time-consuming as well as unnecessarily expensive from a mere healthcare cost point of view. Hence the need to early select only the true beneficiaries while tailoring more effective heart-sparing techniques for the others and streamlining the workflow, especially in high-volume radiation oncology departments. In this literature overview, we collected some possible predictors of cardiac dose sparing in DIBH irradiation for left breast treatment in an effort to provide an easy-to-consult summary of simple instruments to insiders for identifying patients actually benefitting from this technique. We critically reviewed the reliability and weaknesses of each retrieved finding, aiming to inspire new insights and discussions on this much-debated topic.