In Vitro Evaluation of Notch Inhibition to Enhance Efficacy of Radiation Therapy in Melanoma

PURPOSE: The scope of radiation therapy is limited in melanoma. Using in vitro melanoma models, we investigated a Notch signaling inhibitor as a radiosensitizer to explore its potential to improve the efficacy of radiation therapy to widen the clinical application of radiation therapy in melanoma. METHODS AND MATERIALS: Melanoma cell lines A375, SKMEL28, and G361 were grown using standard tissue culture methods. Radiation was delivered with a clinical x-ray unit, and a gamma secretase inhibitor RO4929097 was used to inhibit Notch signaling. Cell viability signal was used to calculate Loewe’s combination index to assess the interaction between radiation and RO4929097 and also the effect of scheduling of radiation and RO4929097 on synergy. Clonogenic assays were used to assess the clonogenic potential. An in vitro 3-dimensional culture model, γ-H2AX, and notch intracellular domain assays were used to interrogate potential underlying biological mechanisms of this approach. Scratch and transwell migration assays were used to assess cell migration. RESULTS: A375 and SKMEL28 cell lines showed consistent synergy for most single radiation doses examined, with a tendency for better synergy with the radiation-first schedule (irradiation performed 24 hours before RO4929097 exposure). Clonogenic assays showed dose-dependent reduction in colony numbers. Both radiation and RO4929097 reduced the size of melanospheres grown in 3-dimensional culture in vitro, where RO4929097 demonstrated a significant effect on the size of A375 and SKMEL28 melanospheres, indicating potential modulation of stem cell phenotype. Radiation induced γ-H2AX foci signal levels were reduced after exposure to RO4929097 with a tendency toward reduction in notch intracellular domain levels for all 3 cell lines. RO4929097 impaired both de novo and radiation-enhanced cell migration. CONCLUSIONS: We demonstrate Notch signaling inhibition with RO4929097 as a promising strategy to potentially improve the efficacy of radiation therapy in melanoma. This strategy warrants further validation in vivo

Changes in the Management of Patients having Radical Radiotherapy for Lung Cancer during the First Wave of the COVID-19 Pandemic in the UK.

AIMS: In response to the COVID-19 pandemic, guidelines on reduced fractionation for patients treated with curative-intent radiotherapy were published, aimed at reducing the number of hospital attendances and potential exposure of vulnerable patients to minimise the risk of COVID-19 infection. We describe the changes that took place in the management of patients with stage I-III lung cancer from April to October 2020. MATERIALS AND METHODS: Lung Radiotherapy during the COVID-19 Pandemic (COVID-RT Lung) is a prospective multicentre UK cohort study. The inclusion criteria were: patients with stage I-III lung cancer referred for and/or treated with radical radiotherapy between 2nd April and 2nd October 2020. Patients who had had a change in their management and those who continued with standard management were included. Data on demographics, COVID-19 diagnosis, diagnostic work-up, radiotherapy and systemic treatment were collected and reported as counts and percentages. Patient characteristics associated with a change in treatment were analysed using multivariable binary logistic regression. RESULTS: In total, 1553 patients were included (median age 72 years, 49% female); 93 (12%) had a change to their diagnostic investigation and 528 (34%) had a change to their treatment from their centre's standard of care as a result of the COVID-19 pandemic. Age ≥70 years, male gender and stage III disease were associated with a change in treatment on multivariable analysis. Patients who had their treatment changed had a median of 15 fractions of radiotherapy compared with a median of 20 fractions in those who did not have their treatment changed. Low rates of COVID-19 infection were seen during or after radiotherapy, with only 21 patients (1.4%) developing the disease. CONCLUSIONS: The COVID-19 pandemic resulted in changes to patient treatment in line with national recommendations. The main change was an increase in hypofractionation. Further work is ongoing to analyse the impact of these changes on patient outcomes

Development of a high-throughput in-vitro radiobiology platform and evaluation of dose-rate, intra-fraction treatment breaks and drug-radiation effects in stereotactic radiotherapy

Stereotactic radiotherapy (SRT), which delivers ablative radiation doses, is increasingly becoming a standard of care in many clinical scenarios. Radiobiological studies help to understand clinical radiotherapy, including SRT, better. In-vitro radiobiological studies designed to explore complexities of SRT, and the large potential experimental space of radiation-drug combinations would require a high-throughput in-vitro system, which should be relevant to clinical radiotherapy. My programme of work led to the development of a high-throughput in-vitro radiobiology platform using an advanced clinical radiotherapy technique, intensity modulated radiotherapy (IMRT) using widely available clinical facilities to recapitulate clinical radiotherapy as close as possible. My work also examined some of clinically relevant radiation physics and clinical parameters that are related to SRT. My work, in contrast with other work showed that there might not significant biological implications of different radiation-doses rates and intra-fraction treatment breaks used in SRT. This could be due to ablative radiation doses used in SRT. Using in-vitro tumour models, I demonstrated a novel radiosensitisation strategy of using Notch inhibition that has a potential for clinical translation in melanoma where, because of its relative radioresistance phenotype could prove to be a successful strategy to widen the clinical application of radiotherapy. My work also showed that Notch inhibition could potentially reduce the risk of development of metastasis and demonstrated potential mechanistic basis for this combined approach. I also demonstrated a novel, first-in-class radiosensitisation approach with a folate depletion strategy based on sound biological rationale with various in-vitro tumour models differing in their radiosensitivities that would require in-vivo validation. My work would hopefully encourage other institutions to develop their own radiobiology programmes using clinical radiotherapy facilities to interrogate potential biological uncertainties of SRT and also expedite pre-clinical evaluation of radiation-drug combinations

Impact of the COVID-19 Pandemic on Outcomes for Patients with Lung Cancer Receiving Curative-intent Radiotherapy in the UK

AIMS: Previous work found that during the first wave of the COVID-19 pandemic, 34% of patients with lung cancer treated with curative-intent radiotherapy in the UK had a change to their centre's usual standard of care treatment (Banfill et al. Clin Oncol 2022;34:19-27). We present the impact of these changes on patient outcomes. MATERIALS AND METHODS: The COVID-RT Lung database was a prospective multicentre UK cohort study including patients with stage I-III lung cancer referred for and/or treated with radical radiotherapy between April and October 2020. Data were collected on patient demographics, radiotherapy and systemic treatments, toxicity, relapse and death. Multivariable Cox and logistic regression were used to assess the impact of having a change to radiotherapy on survival, distant relapse and grade ≥3 acute toxicity. The impact of omitting chemotherapy on survival and relapse was assessed using multivariable Cox regression. RESULTS: Patient and follow-up forms were available for 1280 patients. Seven hundred and sixty-five (59.8%) patients were aged over 70 years and 603 (47.1%) were female. The median follow-up was 213 days (119, 376). Patients with stage I-II non-small cell lung cancer (NSCLC) who had a change to their radiotherapy had no significant increase in distant relapse (P = 0.859) or death (P = 0.884); however, they did have increased odds of grade ≥3 acute toxicity (P = 0.0348). Patients with stage III NSCLC who had a change to their radiotherapy had no significant increase in distant relapse (P = 0.216) or death (P = 0.789); however, they did have increased odds of grade ≥3 acute toxicity (P < 0.001). Patients with stage III NSCLC who had their chemotherapy omitted had no significant increase in distant relapse (P = 0.0827) or death (P = 0.0661). CONCLUSION: This study suggests that changes to radiotherapy and chemotherapy made in response to the COVID-19 pandemic did not significantly affect distant relapse or survival. Changes to radiotherapy, namely increased hypofractionation, led to increased odds of grade ≥3 acute toxicity. These results are important, as hypofractionated treatments can help to reduce hospital attendances in the context of potential future emergency situations.Published version, accepted version (12 month embargo)The article is available via Open Access. Click on the 'Additional link' above to access the full-text