Exploitable mechanisms for combining drugs with radiation: concepts, achievements and future directions

Radiation-targeted immunotherapy: A new perspective in cancer radiotherapy

In contemporary oncology, radiation therapy and immunotherapy stand as critical treatments, each with distinct mechanisms and outcomes. Radiation therapy, a key player in cancer management, targets cancer cells by damaging their DNA with ionizing radiation. Its effectiveness is heightened when used alongside other treatments like surgery and chemotherapy. Employing varied radiation types like X-rays, gamma rays, and proton beams, this approach aims to minimize damage to healthy tissue. However, it is not without risks, including potential damage to surrounding normal cells and side effects ranging from skin inflammation to serious long-term complications. Conversely, immunotherapy marks a revolutionary step in cancer treatment, leveraging the body's immune system to target and destroy cancer cells. It manipulates the immune system's specificity and memory, offering a versatile approach either alone or in combination with other treatments. Immunotherapy is known for its targeted action, long-lasting responses, and fewer side effects compared to traditional therapies. The interaction between radiation therapy and immunotherapy is intricate, with potential for both synergistic and antagonistic effects. Their combined use can be more effective than either treatment alone, but careful consideration of timing and sequence is essential. This review explores the impact of various radiation therapy regimens on immunotherapy, focusing on changes in the immune microenvironment, immune protein expression, and epigenetic factors, emphasizing the need for personalized treatment strategies and ongoing research to enhance the efficacy of these combined therapies in cancer care.

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.

Management of Oncogene Driven Locally Advanced Unresectable Non-small Cell Lung Cancer

INTRODUCTION

The current standard of care of locally advanced non-small cell lung cancer (LA-NSCLC) is concurrent chemoradiation, followed by consolidation durvalumab. However, there is evidence that the efficacy of chemoradiation and also immunotherapy in many oncogene-positive LA-NSCLC are attenuated, and dependent on the subgroup.

AREAS COVERED

We will firstly review the outcomes of standard-of-care therapy in oncogene-driven LA-NSCLC. We looked at various oncogene driven subgroups and the tumor microenvironment that may explain differential response. Finally, we review the role of targeted therapy in the treatment of LA-NSCLC.

EXPERT OPINION

Each oncogene-positive subgroup should be treated as its own entity, and continued efforts should be undertaken to incorporate targeted therapy, which is likely to yield superior survival outcomes if trial design can be optimized and toxicities can be managed.

Cisplatin-based concurrent chemoradiotherapy improved the survival of locoregionally advanced nasopharyngeal carcinoma after induction chemotherapy by reducing early treatment failure

PURPOSE

The aims of this study focusing on Locoregionally advanced nasopharyngeal carcinoma (LANPC) were mainly two-fold: on the one hand, to establish a cut-off value to differentiate early and late failure based on prognosis after recurrence or metastasis; and on the other hand, to investigate the duration of concurrent cisplatin benefit over follow-up time. The results of our study have the potential to guide clinical practice and follow-up.

METHODS

In total, 3123 patients with stage III-IVa NPC receiving Induction chemotherapy followed by concurrent cisplatin or not were analysed. The cut-off value of treatment failure was calculated using the minimum P-value approach. Random survival forest (RSF) model was to simulate the cumulative probabilities of treatment failure (locoregional recurrence and /or distant metastasis) over-time, as well as the monthly time-specific, event-occurring probabilities, for patients at different treatment groups.

RESULTS

Based on subsequent prognosis, early locoregional failure (ELRF) should be defined as recurrence within 14 months (P = 1.47 × 10 - 3), and early distant failure (EDF) should be defined as recurrence within 20 months (P = 1.95 × 10 - 4). A cumulative cisplatin dose (CCD) > 200 mg/m² independently reduced the risk of EDF (hazard ratio, 0.351; 95% confidence interval (CI), 0.169-0.732; P = 0.005). Better failure-free survival (FFS) and overall survival (OS) were observed in concurrent chemotherapy settings ([0 mg/m² vs. 1-200 mg/m² vs. >200 mg/m²]: FFS: 70.4% vs. 74.4% vs. 82.6%, all P < 0.03; OS: 79.5% vs. 83.8% vs. 90.8%, all P < 0.01). In the monthly analysis, treatment failure mainly occurred during the first 4 years, and the risk of distant failure in patients treated with concurrent chemotherapy never exceeded that of patients without concurrent chemotherapy.

CONCLUSION

Locoregional failure that developed within 14 months and/or distant failure within 20 months had poorer subsequent survival. Concurrent chemotherapy provides a significant FFS benefit, primarily by reducing EDF, translating into a long-term OS benefit.

Immune Checkpoint Inhibitors and Chemoradiation for Limited-Stage Small Cell Lung Cancer

OPINION STATEMENT

Limited-stage small cell lung cancer (LS-SCLC) is a potentially curable disease. However, most patients develop disease relapse shortly after definitive treatment. The landmark trials IMpower133 and CASPIAN demonstrated a survival benefit with the addition of immunotherapy to first-line platinum/etoposide for extensive-stage small cell lung cancer. Therefore, it is critical to determine whether advancements in overall survival with immunotherapy can be translated earlier into the treatment paradigm for LS-SCLC. Decades of robust preclinical research into the synergism of radiation therapy and immunotherapy set the stage for the combination of these treatment modalities. Recently published data suggests tolerability of single agent immunotherapy concurrent with chemoradiation in LS-SCLC, along with promising efficacy. However, combination immunotherapy in the consolidation setting appears too toxic, although this may be reflective of the dosing schedule rather than inherent to any combination immune checkpoint blockade. Here, we review underlying mechanisms of synergy with the combination of radiation and immunotherapy, the safety and efficacy of respective treatment modalities, and the ongoing trials that are exploring novel therapeutic approaches for LS-SCLC. Pivotal trials in LS-SCLC are ongoing and anticipated to aid in understanding efficacy and safety of immunotherapy with concurrent platinum-based chemoradiotherapy.

Radiotherapy-induced metabolic hallmarks in the tumor microenvironment

Radiation is frequently administered for cancer treatment, but resistance or remission remains common. Cancer cells alter their metabolism after radiotherapy to reduce its cytotoxic effects. The influence of altered cancer metabolism extends to the tumor microenvironment (TME), where components of the TME exchange metabolites to support tumor growth. Combining radiotherapy with metabolic targets in the TME can improve therapy response. We review the metabolic rewiring of cancer cells following radiotherapy and put these observations in the context of the TME to describe the metabolic hallmarks of radiotherapy in the TME.

Radiotherapy: Brightness and darkness in the era of immunotherapy

The introduction of immunotherapy into cancer treatment has radically changed clinical management of tumors. However, only a minority of patients (approximately 10 to 30%) exhibit long-term response to monotherapy with immunotherapy. Moreover, there are still many cancer types, including pancreatic cancer and glioma, which are resistant to immunotherapy. Due to the immunomodulatory effects of radiotherapy, the combination of radiotherapy and immunotherapy has achieved better therapeutic effects in a number of clinical trials. However, radiotherapy is a double-edged sword in the sense that it also attenuates the immune system under certain doses and fractionation schedules, not all clinical trials show improved survival in the combination of radiotherapy and immunotherapy. Therefore, elucidation of the interactions between radiotherapy and the immune system is warranted to optimize the synergistic effects of radiotherapy and immunotherapy. In this review, we highlight the dark side as well as bright side of radiotherapy on tumor immune microenvironment and immune system. We also elucidate current status of radioimmunotherapy, both in preclinical and clinical studies, and highlight that combination of radiotherapy and immunotherapy attenuates combinatorial effects in some circumstances. Moreover, we provide insights for better combination of radiotherapy and immunotherapy.

Managing Central Nervous System Spread of Lung Cancer: The State of the Art

Brain metastases (BrM) are common in both non-small-cell lung cancer and small-cell lung cancer. Substantial progress in BrM management has occurred in the past decade related to advances in both radiation and medical oncology. Recent and ongoing radiation trials have focused on increasing the candidacy for focal therapy of BrM with stereotactic radiosurgery; reducing the toxicity and improving patient selection for whole brain radiotherapy; and, in small-cell lung cancer, evaluating brain magnetic resonance imaging surveillance without prophylactic cranial irradiation, hippocampal avoidance in prophylactic cranial irradiation and whole brain radiotherapy, and the role of upfront stereotactic radiosurgery for BrM. In medical oncology, the development of multiple tyrosine kinase inhibitors with encouraging CNS activity and emerging data on the CNS activity of immune checkpoint inhibitors in some patients have opened the door to novel systemic and multidisciplinary treatment strategies for the management of BrM. Future research will focus on more robust characterizations of the CNS activity of targeted therapy and immunotherapies, as well as optimal integration and patient selection for multidisciplinary strategies involving CNS-active drugs, radiation therapy, and CNS surveillance.

Clinical factors affecting the determination of radiotherapy-induced skin toxicity in breast cancer

Purpose

Radiotherapy is essential for the treatment of breast cancer (BC). However, adverse effects may occur in healthy tissue, during treatment and even after several months. Although it is known that this clinical radiosensitivity is multifactorial, the factors involved are unknown yet. In this study, we evaluated the effect of these factors on the development of radiodermatitis in patients undergoing radiotherapy.

Materials and Methods

Demographic and lifestyle data collected during face-to-face interviews of 122 BC patients and data from clinical records were investigated. Most patients underwent conventional three-dimensional radiotherapy treatment. A total dose of 50 Gy was administered (2 Gy/day), followed by a boost in a tumor bed with a total dose of 18 Gy (2 Gy/day). Radiotoxicity was evaluated weekly using the Radiation Therapy Oncology Group classification system (range, 0 to 4, according to the severity).

Results

In the present study, 75.4% of patients presented acute skin toxic effects with different degrees of severity. In 25% of cases, these effects manifested at the end of the fourth week at a cumulative dose of 40 Gy. The association of grade ≥2 acute skin reactions with body mass index (BMI) and breast size and between grade 3–4 and age was positive compared with controls. However, the role of the other factors could not be confirmed.

Conclusion

Analysis of the factors related to individual radiosensitivity suggests that age, BMI and breast size play an important role in the development of acute skin toxicity during treatment. Particular attention to patients who present these characteristics would help to control treatment effectiveness and therefore optimize their quality of life.

Moving towards the Future of Radio-Immunotherapy: Could We “Tailor” the Abscopal Effect on Head and Neck Cancer Patients?

The abscopal effect (AbE) is defined as radiation-induced shrinkage of distant, non-treated, neoplastic lesions and it is considered the best clinical picture of the efficient immune stimulation by irradiation. The first report about abscopal tumor regression upon radiotherapy dates back to the beginning of the 20th century. The growing preclinical and clinical synergism between radiation and immunotherapy gave birth the purpose to more easily reproduce the abscopal effect, nevertheless, it is still rare in clinical practice. In this review we summarize immunological modulation of radiotherapy, focusing on the well-balanced equilibrium of tumor microenvironment and how radio-immunotherapy combinations can perturb it, with particular attention on head and neck squamous cell cancer. Finally, we investigate future perspectives, with the aim to “tailor” the abscopal effect to the patient.

Clinical and Preclinical Outcomes of Combining Targeted Therapy With Radiotherapy

In the era of precision medicine, radiation medicine is currently focused on the precise delivery of highly conformal radiation treatments. However, the tremendous developments in targeted therapy are yet to fulfill their full promise and arguably have the potential to dramatically enhance the radiation therapeutic ratio. The increased ability to molecularly profile tumors both at diagnosis and at relapse and the co-incident progress in the field of radiogenomics could potentially pave the way for a more personalized approach to radiation treatment in contrast to the current ‘‘one size fits all’’ paradigm. Few clinical trials to date have shown an improved clinical outcome when combining targeted agents with radiation therapy, however, most have failed to show benefit, which is arguably due to limited preclinical data. Several key molecular pathways could theoretically enhance therapeutic effect of radiation when rationally targeted either by directly enhancing tumor cell kill or indirectly through the abscopal effect of radiation when combined with novel immunotherapies. The timing of combining molecular targeted therapy with radiation is also important to determine and could greatly affect the outcome depending on which pathway is being inhibited.

Ultrasound augments on-demand breast tumor radiosensitization and apoptosis through a tri-responsive combinatorial delivery theranostic platform

Advanced inoperable triple-negative breast cancer (TNBC) comprises aggressive tumors with a modest pathological response to neoadjuvant chemotherapy. The concomitant use of chemoradiotherapy improves the pathological response rates. However, the dose-dependent systemic toxicity of clinical radiosensitizers with poor circulation half-life and limited passive bioavailability limits their clinical utility. We address these challenges by rationally designing a stealth and tumor microenvironment responsive nano-conjugate platform for the ultrasound-mediated on-demand spatio-temporal delivery of plant flavonoid curcumin as a combinatorial regimen with clinically approved paclitaxel for the neoadjuvant chemoradiotherapy of locally advanced triple-negative breast cancer (TNBC). Interestingly, the focused application of ultrasound at the orthotopic TNBC xenograft of NOD-SCID mice facilitated the immediate infiltration of nano-conjugates at the tumor interstitium, and conferred in vivo safety over marketed paclitaxel formulation. In addition, curcumin significantly potentiated the in vivo chemoradiotherapeutic efficacy of paclitaxel upon loading into nano-conjugates. This gets further enhanced by the concurrent pulse of ultrasound, as confirmed by PET-CT imaging, along with a significant improvement in the mice survival. The quadrapeutic apoptotic effect by the combination of paclitaxel, curcumin, radiation, and ultrasound, along with a reduction in the tumor microvessel density and cell proliferation marker, confers the broad chemo-radiotherapeutic potential of this regimen for radio-responsive solid tumors, as well as metastatic niches.

Combining Radiation Therapy with ALK Inhibitors in Anaplastic Lymphoma Kinase-Positive Non-Small Cell Lung Cancer (NSCLC): A Clinical and Preclinical Overview

Over the past years, the identification of genetic alterations in oncogenic drivers in non-small cell lung cancer (NSCLC) has significantly and favorably transformed the outcome of patients who can benefit from targeted therapies such as tyrosine kinase inhibitors. Among these genetic alterations, anaplastic lymphoma kinase (ALK) rearrangements were discovered in 2007 and are present in 3-5% of patients with NSCLC. In addition, radiotherapy remains one of the cornerstones of NSCLC treatment. Moreover, improvements in the field of radiotherapy with the use of hypofractionated or ablative stereotactic radiotherapy have led to a better outcome for localized or oligometastatic NSCLC. To date, the effects of the combination of ALK inhibitors and radiotherapy are unclear in terms of safety and efficacy but could potently improve treatment. In this manuscript, we provide a clinical and preclinical overview of combining radiation therapy with ALK inhibitors in anaplastic lymphoma kinase-positive non-small cell lung cancer.

Combining radiotherapy with targeted therapies in non-small cell lung cancer: focus on anti-EGFR, anti-ALK and anti-angiogenic agents

The combination of radiotherapy (RT) with targeted agents in non-small cell lung cancer (NSCLC) has been expected to improve the therapeutic ratio and tumor control. The EGFR blockade enhances the antitumor effect of RT. The ALK inhibition elicits anti-proliferative, pro-apoptotic and antiangiogenic effects in ALK-positive NSCLC cell lines, enhanced by the exposure to RT. The antiangiogenic agents normalize pathological tumor vessels, thus decrease tumor cell hypoxia and improve radiosensitivity. To date, however, none of the targeted agents combined with RT has shown proven clinical benefit over standard chemoradiation (CRT) in locally advanced NSCLC. The risk of potential excessive toxicity related to the therapeutic combination of RT and targeted agents cannot be ignored. Well-designed clinical trials may allow development of more effective combination strategies. Another potential application of combined RT and targeted therapies in oncogene-driven NSCLC is metastatic oligoprogressive or oligopersistent disease. The use of RT in oligoprogressive oncogene-driven NSCLC, while continuing first line targeted therapy, can potentially eradicate resistant cell clones and provide survival benefit. Likewise, the consolidation of oligopersistent foci (molecularly resistant to first line targeted therapy) may potentially interfere with the natural course of the disease by avoiding or delaying progression. We discuss here the molecular and radiobiological mechanisms of combining RT and targeted agents, and summarize current clinical experience.

Phase I trial of the MEK inhibitor selumetinib in combination with thoracic radiotherapy in non-small cell lung cancer

Background

The RAS/RAF/MEK/ERK signalling pathway has a pivotal role in cancer proliferation and modulating treatment response. Selumetinib inhibits MEK and enhances effects of radiotherapy in preclinical studies.

Patients and methods

Single-arm, single-centre, open-label phase I trial. Patients with stage III NSCLC unsuitable for concurrent chemo-radiotherapy, or stage IV with dominant thoracic symptoms, were recruited to a dose-finding stage (Fibonacci 3 + 3 design; maximum number = 18) then an expanded cohort (n = 15). Oral selumetinib was administered twice daily (starting dose 50 mg) commencing 7 days prior to thoracic radiotherapy, then with radiotherapy (6-6.5 weeks; 60-66 Gy/30-33 fractions). The primary objective was to determine the recommended phase II dose (RP2D) of selumetinib in combination with thoracic radiotherapy.

Results

21 patients were enrolled (06/2010-02/2015). Median age: 62y (range 50-73). M:F ratio 12(57%):9(43%). ECOG PS 0:1, 7(33%):14(67%). Stage III 16(76%); IV 5(24%). Median GTV 64 cm³ (range 1-224 cm³). 15 patients comprised the expanded cohort at starting dose. All 21 patients completed thoracic radiotherapy as planned and received induction chemotherapy. 13 (62%) patients received the full dose of selumetinib.In the starting cohort no enhanced radiotherapy-related toxicity was seen. Two patients had dose-limiting toxicity (1x grade 3 diarrhoea/fatigue and 1x pulmonary embolism). Commonest grade 3-4 adverse events: lymphopaenia (19/21 patients) and hypertension (7/21 patients). One patient developed grade 3 oesophagitis. No patients developed grade ≥3 radiation pneumonitis. Two patients were alive at the time of analysis (24 and 26 months follow-up, respectively). Main cause of first disease progression: distant metastases ± locoregional progression (12/21 [57.1%] patients). Six patients had confirmed/suspected pneumocystis jiroveci pneumonia.

Conclusion

We report poor outcome and severe lymphopenia in most patients treated with thoracic radiotherapy and selumetinib at RP2D in combination, contributing to confirmed/clinically suspected pneumocystis jiroveci pneumonia. These results suggest that this combination should not be pursued in a phase II trial.ClinicalTrials.gov reference: NCT01146756.

The Role of Theranostics in Prostate Cancer

Theranostics in men with metastatic castration-resistant prostate cancer (mCRPC) has been developed to target bone and the tumor itself. Currently, bone-directed targeted alpha therapy with radium-223 (²²³Ra) is the only theranostic agent proven to prolong survival in men with mCRPC who have symptomatic bone metastases and no known visceral metastases. The clinical utility and therapeutic success of ²²³Ra has encouraged the development of other tumor-targeting theranostic agents in mCRPC, primarily targeting prostate-specific membrane antigen (PSMA) with radioligand therapy (RLT). There is increasing evidence of promising response rates and a low toxicity profile with ¹⁷⁷Lu-labeled PSMA RLT in patients with mCRPC. A phase III randomized study of ¹⁷⁷Lu-labeled PSMA RLT has completed accrual and is awaiting results as to whether the drug improves radiographic progression-free survival and overall survival in men with mCRPC receiving standard of care treatments. Additional early clinical trials are investigating the role of tumor-directed targeted alpha therapy with radiotracers such as ²²⁵Ac. In this article, we review the current status of theranostics in prostate cancer, discussing the challenges and opportunities of combination therapies with more conventional agents such as androgen receptor inhibitors, cytotoxic chemotherapy, and immunotherapy.

The Promise of Combining Radiation Therapy With Immunotherapy

The development of immunotherapy in oncology builds upon many years of scientific investigation into the cellular mechanics underlying interactions between tumor cells and immune cell populations. The past decade has brought an accelerating pace to the clinical investigation of new immunotherapy agents, particularly in the setting of metastatic disease. The integration of immunotherapy into phase 3 clinical trial design has lagged in settings of advanced locoregional disease, where combination with radiation therapy may be critical. Yet, such may be the settings where immunotherapies have their greatest potential to affect patient survival and achieve curative outcomes. In this review, we discuss the interaction of radiation with the immune system and the potential to augment antitumor immunity through combined-modality approaches that integrate radiation and immunotherapies. The dynamics of cellular and tumor response to radiation offer unique opportunities for beneficial interplay with immunotherapy that may go unrecognized with conventional screening and monotherapy clinical testing of novel pharmaceutical agents. Using immune checkpoint blockade as a primary example, we discuss recent preclinical and clinical studies that illustrate the potential synergy of such therapies in combination with radiation, and we highlight the potential clinical value of such interactions. For various immunotherapy agents, their greatest clinical effect may rest in combination with radiation, and efforts to facilitate systematic investigation of this approach are highly warranted.

Recent Progress of Potentiating Immune Checkpoint Blockade with External Stimuli-an Industry Perspective

The past decade has seen the materialization of immune checkpoint blockade as an emerging approach to cancer treatment. However, the overall response and patient survival are still modest. Various efforts to study the "cancer immunogram" have highlighted complex biology that necessitates a multipronged approach. This includes increasing the antigenicity of the tumor, strengthening the immune infiltration in the tumor microenvironment, removing the immunosuppressive mechanisms, and reducing immune cell exhaustion. The coordination of these approaches, as well as the ability to enhance them through delivery, is evaluated. Due to their success in multiple preclinical models, external-stimuli-responsive nanoparticles have received tremendous attention. Several studies report success in distantly located tumor regression, metastases, and reoccurrence in preclinical mouse models. However, clinical translation in this space remains low. Herein, the recent advancement in external-stimuli-responsive nanoconstruct-synergized immune checkpoint blockade is summarized, offering an industry perspective on the limitations of current academic innovations and discussing challenges in translation from a technical, manufacturing, and regulatory perspective. These limitations and challenges will need to be addressed to establish external-stimuli-based therapeutic strategies for patients.

Sequential Versus Concurrent Thoracic Radiotherapy in Combination With Cisplatin and Etoposide for N3 Limited-Stage Small-Cell Lung Cancer

At present, concurrent chemoradiotherapy (CRT) is considered the standard treatment of limited-stage small cell lung cancer (LS-SCLC). However, LS-SCLC is highly heterogeneous in the T stage, N stage, and prognosis. Increasing evidence has shown that individual treatment should be considered when treating LS-SCLC patients. The aim of the present study was to explore the optimal combination model of thoracic radiotherapy (TRT) and chemotherapy in N3 LS-SCLC. We retrospectively analyzed 93 N3 LS-SCLC patients treated in the Department of Oncology of Binzhou Medical University Hospital (Shandong, China) between March 2010 and October 2015. A total of 52 (52/93; 55.9%) patients received sequential CRT, and 41 (41/93; 44.1%) patients received concurrent CRT. All patients received 4-6 cycles of chemotherapy and TRT (50-60 Gy). The median follow-up time was 25.4 months (range was 6-65 months).The overall response rate was 88.5% in the sequential CRT group (9.6% complete response rate and 78.8% partial response rate) and 90.2% in the concurrent CRT group (14.6% complete response rate and 75.6% partial response rate). The PFS and OS were 15.4 months and 19.1 months in sequential CRT group, and 16.9 months and 20.5 months in concurrent CRT group. There was no significant difference in treatment response rate, PFS, and OS between sequential and concurrent CRT patients. The most common treatment-related toxicities were nausea/vomiting, neutropenia, and esophagitis. In conclusion, when concurrent CRT is performed in N3 LS-SCLC patients, tolerance to treatment should be fully considered. In our study, sequential CRT and concurrent CRT showed the same efficacy, and sequential CRT demonstrated better tolerance. However, these results require confirmation in future follow-up studies.

Radium-223 mechanism of action: implications for use in treatment combinations

The targeted alpha therapy radium-223 (223Ra) can prolong survival in men with castration-resistant prostate cancer (CRPC) who have symptomatic bone metastases and no known visceral metastases. Preclinical studies demonstrate that 223Ra preferentially incorporates into newly formed bone matrix within osteoblastic metastatic lesions. The emitted high-energy alpha particles induce DNA double-strand breaks that might be irreparable and lead to cell death in nearby exposed tumour cells, osteoblasts and osteoclasts. Consequently, tumour growth and abnormal bone formation are inhibited by these direct effects and by the disruption of positive-feedback loops between tumour cells and the bone microenvironment. 223Ra might also modulate immune responses within the bone. The clinical utility of 223Ra has encouraged the development of other anticancer targeted alpha therapies. A thorough understanding of the mechanism of action could inform the design of new combinatorial treatment strategies that might be more efficacious than monotherapy. On the basis of the current mechanistic knowledge and potential clinical benefits, combination therapies of 223Ra with microtubule-stabilizing cytotoxic drugs and agents targeting the androgen receptor axis, immune checkpoint receptors or DNA damage response proteins are being explored in patients with CRPC and metastatic bone disease.

18F-FDG-PET/CT-based treatment planning for definitive (chemo)radiotherapy in patients with head and neck squamous cell carcinoma improves regional control and survival

BACKGROUND AND PURPOSE

Multimodality imaging including ¹⁸F-FDG-PET has improved the detection threshold of nodal metastases in head and neck squamous cell carcinoma (HNSCC). The aim of this retrospective analysis is to investigate the impact of FDG-PET/CT-based nodal target volume definition (FDG-PET/CT-based NTV) on radiotherapy outcomes, compared to conventional CT-based nodal target volume definition (CT-based NTV).

MATERIALS AND METHODS

Six-hundred-thirty-three patients treated for HNSCC with definitive (chemo)radiotherapy using IMRT/VMAT techniques between 2008 and 2017 were analyzed. FDG-PET/CT-based NTV was performed in 46% of the patients. The median follow-up was 31 months. Diagnostic imaging depicting the regional recurrence was co-registered with the initial CT-scan to reconstruct the exact site of the recurrence. Multivariate Cox regression analysis was performed to identify variables associated with radiotherapy outcome.

RESULTS

FDG-PET/CT-based NTV improved control of disease in the CTV_{elective-nodal} (HR: 0.33, p = 0.026), overall regional control (HR: 0.62, p = 0.027) and overall survival (HR: 0.71, p = 0.033) compared to CT-based NTV. The risk for recurrence in the CTV_{elective-nodal} was increased in case of synchronous local recurrence of the primary tumor (HR: 12.4, p < 0.001).

CONCLUSION

FDG-PET/CT-based NTV significantly improved control of disease in the CTV_{elective-nodal}, overall regional control and overall survival compared to CT-based NTV. A significant proportion of CTV_{elective-nodal} recurrences are potentially new nodal manifestations from a synchronous local recurrent primary tumor. These results support the concept of target volume transformation and give an indication of the potential of FDG-PET to guide gradual radiotherapy dose de-escalation in elective neck treatment in HNSCC.

Radio-selective effects of a natural occurring muscle-derived dipeptide in A549 and normal cell lines

Radiotherapy (RT) causes morbidity and long-term side effects. A challenge in RT is to maximize cancer cells killing while minimizing damage to normal tissue. The ideal radio-protector selectively improves survival and limits damage to normal tissues while reducing survival of cancer cells. Muscle-derived dipeptide, L-carnosine (CAR) is a potent antioxidant, with radio-protective, but also anticancer properties, affecting the cell cycle of cancer cells. We tested CAR effects in lung cancer cells, differentiated and undifferentiated normal cells. We hypothesized that CAR antioxidant properties will confer protection to the two normal cell lines against RT, while preventing lung cancer cell proliferation, and that CAR may act as a radiosensitizer of lung cancer cells due to its effects on cell-cycle progression of cancer cells. Under the experimental conditions reported here, we found that CAR increased radio-sensitivity of lung (A549) cancer cells by increasing the percentage of cells in G2/M (radiosensitive) phase of cell cycle, it negatively affected their bioenergetics, therefore reduced their viability, and DNA-double strand break repair capacity. CAR had either no effect or reduced RT-induced damage in normal cells, depending on the cell type. CAR is a versatile natural occurring compound, that could improve RT-induced lung cancer cells killing, while reducing the damage to normal differentiated and undifferentiated cells.

Radium-223 in combination with docetaxel in patients with castration-resistant prostate cancer and bone metastases: a phase 1 dose escalation/randomised phase 2a trial

Purpose:

Radium 223 dichloride (radium-223) is an alpha particle–emitting bone-directed therapy that prolongs overall survival in men with bone-predominant metastatic castration-resistant prostate cancer (mCRPC). Docetaxel is an antimicrotubule cytotoxic agent that improves survival in mCRPC. We investigated whether combining these potentially cross-sensitising agents to dually target tumour and bone would be safe and effective.

Patients and methods:

Phase 1 was a dose escalation study to define a recommended phase 2 dose (RP2D) of docetaxel and radium-223. In phase 2a, patients were randomised 2:1 to the recommended combination regimen or docetaxel at a dose of 75 mg/m² every 3 weeks (q3w). Patients with bone-predominant mCRPC were eligible. End-points were safety, efficacy and treatment-related changes in serum and imaging biomarkers.

Results:

Twenty patients were enrolled in phase 1; 53 patients were randomised in phase 2a: 36 to combination treatment and 17 to docetaxel alone. The RP2D for the combination was radium-223 55 kBq/kg every six weeks × 5 doses, plus docetaxel 60 mg/m² q3w × 10 doses. Febrile neutropenia was dose limiting. A higher rate of febrile neutropenia was seen in the docetaxel monotherapy arm (15% vs 0%); the safety profile of the treatment groups was otherwise similar. The combination arm had more durable suppression of prostate-specific antigen (median time to progression, 6.6 vs 4.8 months, respectively), alkaline phosphatase (9 vs 7 months) and osteoblastic bone deposition markers.

Conclusions:

Radium-223 in combination with docetaxel at the RP2D was well tolerated. Exploratory efficacy data suggested enhanced antitumour activity for the combination relative to docetaxel alone. Comparative studies with end-points of clinical benefit are warranted. ClinicalTrials.gov number: NCT01106352.

Combining precision radiotherapy with molecular targeting and immunomodulatory agents: a guideline by the American Society for Radiation Oncology

The practice of radiation oncology is primarily based on precise technical delivery of highly conformal, image-guided external beam radiotherapy or brachytherapy. However, systematic research efforts are being made to facilitate individualised radiation dose prescriptions on the basis of gene-expressssion profiles that reflect the radiosensitivity of tumour and normal tissue. This advance in precision radiotherapy should complement those benefits made in precision cancer medicine that use molecularly targeted agents and immunotherapies. The personalisation of cancer therapy, predicated largely on genomic interrogation, is facilitating the selection of therapies that are directed against driver mutations, aberrant cell signalling, tumour microenvironments, and genetic susceptibilities. With the increasing technical power of radiotherapy to safely increase local tumour control for many solid tumours, it is an opportune time to rigorously explore the potential benefits of combining radiotherapy with molecular targeted agents and immunotherapies to increase cancer survival outcomes. This theme provides the basis and foundation for this American Society for Radiation Oncology guideline on combining radiotherapy with molecular targeting and immunotherapy agents.

NQO1-dependent, Tumor-selective Radiosensitization of Non-small Cell Lung Cancers

PURPOSE

Development of tumor-specific therapies for the treatment of recalcitrant non-small cell lung cancers (NSCLC) is urgently needed. Here, we investigated the ability of β-lapachone (β-lap, ARQ761 in clinical form) to selectively potentiate the effects of ionizing radiation (IR, 1-3 Gy) in NSCLCs that overexpress NAD(P)H:Quinone Oxidoreductase 1 (NQO1).

EXPERIMENTAL DESIGN

The mechanism of lethality of low-dose IR in combination with sublethal doses of β-lap was evaluated in NSCLC lines in vitro and validated in subcutaneous and orthotopic xenograft models in vivo. Pharmacokinetics and pharmacodynamics (PK/PD) studies comparing single versus cotreatments were performed to validate therapeutic efficacy and mechanism of action.

RESULTS

β-Lap administration after IR treatment hyperactivated PARP, greatly lowered NAD⁺/ATP levels, and increased double-strand break (DSB) lesions over time in vitro. Radiosensitization of orthotopic, as well as subcutaneous, NSCLCs occurred with high apparent cures (>70%), even though 1/8 β-lap doses reach subcutaneous versus orthotopic tumors. No methemoglobinemia or long-term toxicities were noted in any normal tissues, including mouse liver that expresses the highest level of NQO1 (∼12 units) of any normal tissue. PK/PD responses confirm that IR + β-lap treatments hyperactivate PARP activity, greatly lower NAD⁺/ATP levels, and dramatically inhibit DSB repair in exposed NQO1⁺ cancer tissue, whereas low NQO1 levels and high levels of catalase in associated normal tissue were protective.

CONCLUSIONS

Our data suggest that combination of sublethal doses of β-lap and IR is a viable approach to selectively treat NQO1-overexpressing NSCLC and warrant a clinical trial using low-dose IR + β-lap against patients with NQO1⁺ NSCLCs.

Harnessing drug/radiation interaction through daily routine practice: Leverage medical and methodological point of view (MORSE 02-17 study)

BACKGROUND

Safety profile of the interaction between anticancer drugs and radiation is a recurrent question. However, there are little data regarding the non-anticancer treatment (NACT)/radiation combinations. The aim of the present study was to investigate concomitant NACTs in patients undergoing radiotherapy in a French comprehensive cancer center.

METHODS

A prospective cross-sectional study was conducted. All cancer patients undergoing a palliative or curative radiotherapy were consecutively screened for six weeks in 2016. Data on NACTs were collected.

RESULTS

Out of 214 included patients, a NACT was concomitantly prescribed to 155 patients (72%), with a median number of 5 NACTs per patient (range: 1-12). The most prescribed drugs were anti-hypertensive drugs (101 patients, 47.2%), psychotropic drugs (n = 74, 34.6%), analgesics (n = 78, 36.4%), hypolipidemic drugs (n = 57, 26.6%), proton pump inhibitors (n = 46, 21.5%) and antiplatelet drugs (n = 38, 17.8%). Although 833 different molecules were reported, only 20 possible modifiers of cancer biological pathways (prescribed to 74 patients (34.5%)) were identified. Eight out of the 833 molecules (0.9%), belonging to six drug families, have been investigated in 28 ongoing or published clinical trials in combo with radiotherapy. They were prescribed to 63 patients (29.4%).

CONCLUSION

Drug-radiation interaction remains a subject of major interest, not only for conventional anticancer drugs, but also for NACTs. New trial designs are thus required.

The hypoxia-activated prodrug evofosfamide in combination with multiple regimens of radiotherapy

The promising treatment combination of ionizing radiation (IR) with a hypoxia-activated prodrug (HAP) is based on biological cooperation. Here we investigated the hypoxia-activated prodrug evofosfamide in combination with different treatment regimens of IR against lung A549- and head&neck UT-SCC-14-derived tumor xenografts. DNA damage-related endpoints and clonogenic cell survival of A549 and UT-SCC-14 carcinoma cells were probed under normoxia and hypoxia.Evofosfamide (TH-302) induced DNA-damage and a dose-dependent antiproliferative response in A549 cells on cellular pretreatment under hypoxia, and supra-additively reduced clonogenic survival in combination with IR. Concomitant treatment of A549-derived tumor xenografts with evofosfamide and fractionated irradiation induced the strongest treatment response in comparison to the corresponding neoadjuvant and adjuvant regimens. Adjuvant evofosfamide was more potent than concomitant and neoadjuvant evofosfamide when combined with a single high dose of IR. Hypoxic UT-SCC-14 cells and tumor xenografts thereof were resistant to evofosfamide alone and in combination with IR, most probably due to reduced P450 oxidoreductase expression, which might act as major predictive determinant of sensitivity to HAPs.In conclusion, evofosfamide with IR is a potent combined treatment modality against hypoxic tumors. However, the efficacy and the therapeutic outcome of this combined treatment modality is, as indicated here in preclinical tumor models, dependent on scheduling parameters and tumor type, which is most probably related to the status of respective HAP-activating oxidoreductases. Further biomarker development is necessary for the launch of successful clinical trials.

Cytotoxic Effects of the Therapeutic Radionuclide Rhenium-188 Combined with Taxanes in Human Prostate Carcinoma Cell Lines

OBJECTIVE

Rhenium-188-HEDP is an effective radiopharmaceutical for the treatment of painful bone metastases from prostate cancer. The effectiveness of the β-radiation emitted by ¹⁸⁸Re might be enhanced by combination with chemotherapy, using the radiosensitization concept. Therefore, the authors investigated the combined treatment of the taxanes, docetaxel and cabazitaxel, with ¹⁸⁸Re in prostate carcinoma cell lines.

MATERIALS AND METHODS

The cytotoxic effects of single and combined treatment with taxanes and ¹⁸⁸Re were investigated in three human prostate carcinoma cell lines (PC-3, DU 145, and LNCaP), using the colony-forming assay. The half maximal effective concentration (EC50) of all individual agents was determined. The combined treatment was studied at 0.25, 0.5, 1, 2, and 4 times the EC50 of each agent. The interaction was investigated with a regression model.

RESULTS

The survival curves showed dose-dependent cell growth inhibition for both the taxanes and ¹⁸⁸Re. The regression model showed a good capability of explaining the data. It proved additivity in all combination experiments and confirmed a general trend to a slight subadditive effect.

CONCLUSIONS

This proof-of-mechanism study exploring radiosensitization by combining ¹⁸⁸Re and taxanes showed no synergism, but significant additivity. This encourages the design of in vivo studies. Future research should explore the potential added value of concomitant treatment of bone metastases with chemotherapy and ¹⁸⁸Re-HEDP.

Radiation effects on the tumor microenvironment: Implications for nanomedicine delivery

The tumor microenvironment has an important influence on cancer biological and clinical behavior and radiation treatment (RT) response. However, RT also influences the tumor microenvironment in a complex and dynamic manner that can either reinforce or inhibit this response and the likelihood of long-term disease control in patients. It is increasingly evident that the interplay between RT and the tumor microenvironment can be exploited to enhance the accumulation and intra-tumoral distribution of nanoparticles, mediated by changes to the vasculature and stroma with secondary effects on hypoxia, interstitial fluid pressure (IFP), solid tissue pressure (STP), and the recruitment and activation of bone marrow-derived myeloid cells (BMDCs). The use of RT to modulate nanoparticle drug delivery offers an exciting opportunity to improve antitumor efficacy. This review explores the interplay between RT and the tumor microenvironment, and the integrated effects on nanoparticle drug delivery and efficacy.

From chemotherapy to target therapies associated with radiation in the treatment of NSCLC: a durable marriage?

INTRODUCTION

The integration between radiotherapy and drugs, from chemotherapy to recently available target therapies, continues to have a relevant role in the treatment of locally advanced and metastatic Non-small cell lung cancer (NSCLC). Aim of the present review is to evaluate the promising and emerging application of the best interaction between new drugs and new modalities of radiotherapy. Areas covered: We searched Medline, Google Scholar, PubMed, ProQuest Dissertation, and Theses databases for reports published in English. A study was included when it reported on cancer-related radiotherapy and included patients with NSCLC treated with chemo and/or target therapies. Review articles were excluded from the analysis. Expert commentary: Chemo-radiotherapy still represents the standard of choice in locally advanced NSCLC, while to date the addition of target therapies to chemo-radiotherapy did not demonstrate any robust advantage in this stage of disease. Considering the absence of randomized controlled trials, the role of target therapies in early stage adjuvant NSCLC is not yet recommended in clinical practice. On the contrary, in the setting of oligometastatic and oligoprogressive disease, new molecules demonstrated to be safe and effective, opening to a promising and emerging application of the best interaction between new drugs and new modalities of radiotherapy.

Bladder Sparing Approaches for Muscle-Invasive Bladder Cancers

Organ preservation has been increasingly utilised in the management of muscle-invasive bladder cancer. Multiple bladder preservation options exist, although the approach of maximal TURBT performed along with chemoradiation is the most favoured. Phase III trials have shown superiority of chemoradiotherapy compared to radiotherapy alone. Concurrent chemoradiotherapy gives local control outcomes comparable to those of radical surgery, but seemingly more superior when considering quality of life. Bladder-preserving techniques represent an alternative for patients who are unfit for cystectomy or decline major surgical intervention; however, these patients will need lifelong rigorous surveillance. It is important to emphasise to the patients opting for organ preservation the need for lifelong bladder surveillance as risk of recurrence remains even years after radical chemoradiotherapy treatment. No randomised control trials have yet directly compared radical cystectomy with bladder-preserving chemoradiation, leaving the age-old question of superiority of one modality over another unanswered. Radical cystectomy and chemoradiation, however, must be seen as complimentary treatments rather than competing treatments. Meticulous patient selection is vital in treatment modality selection with the success of recent trials within the field of bladder preservation only being possible through this application of meticulous selection criteria compared to previous decades. A multidisciplinary approach with radiation oncologists, medical oncologists, and urologists is needed to closely monitor patients who undergo bladder preservation in order to optimise outcomes.

The rationale of combined radiotherapy and chemotherapy - Joint action of Castor and Pollux

This article aims to review the rationale behind the combination of radiotherapy and chemotherapy. Theoretical concepts describing the principles of the joint effects of chemoradiotherapy are reviewed. Preclinical and clinical evidence are collected and summarised demonstrating the co-operation between the two modalities which form the mainstay of the treatment of most solid tumours. Initially, the evolution of chemoradiotherapy was mostly empirically driven which is true for both, the early studies and the experimental investigations, rather than relying on scientific rationale. To date, the revised Steel's model proposes five mechanisms, spatial cooperation, cytotoxic enhancement, biological co-operation, temporary modulation and normal tissue protection to describe the interaction between radiotherapy and chemotherapy. Chemoradiotherapy has become the standard modality for most patients with locally advanced solid tumours due to better control of loco-regional disease and prolonged survival. Gradually, molecular prediction of efficacy is integrated such as MGMT status for combining temozolomide with radiotherapy in glioblastoma. As molecular targeted drugs are ready to be taken into triple combinations with chemoradiotherapy it is crucial to have a good understanding of the mechanisms of chemoradiotherapy for the rational development of future combinations.

Targeted agents in GI radiotherapy: Clinical efficacy and side effects

Approximately 50% of all patients with cancer receive radiotherapy (RT) at some point during their treatment. Despite the advent of modern imaging and advances in planning and delivering highly-conformal and precise RT, further dose escalation to improve clinical outcome is often limited by the potential side-effects to adjacent tissues. Addition of chemotherapy to radiotherapy (CRT) has led to significant clinical improvements in many gastrointestinal malignancies but at the expense of increased toxicity as most chemotherapy drugs lack specificity. Targeted agents modulate specific biological pathways and can potentially enhance RT efficacy. However, so far, the majority of clinical studies incorporating targeted agents into RT and CRT have produced disappointing results in gastrointestinal malignancies. Also, we lack validated biomarkers and methods for monitoring and predicting the efficacy of these agents when combined with RT/CRT. In the present article, we will review the most important targeted therapies, and examine the efficacy and toxicity of these agents when combined with RT/CRT in gastrointestinal malignancies. The shortcomings as well as future challenges and perspectives for the successful use of these compounds with RT/CRT in future trials will also be outlined.

Hyperthermia and radiotherapy in bladder cancer

Hyperthermia represents a unique, safe, and advantageous methodology for improving therapeutic strategies in the management of bladder cancer. This modality has shown promise in contributing to treatment regimens for both superficial and muscle-invasive disease. Especially in conjunction with intravesical chemotherapy, systemic therapy, and radiotherapy, hyperthermia shows particular synergistic benefit. As such, it should be explored further through clinical use and clinical trial in conjunction with currently available techniques and emerging technologies. However, to conceptualise the way forward, it is particularly important to understand the current challenges to widespread use of non-invasive, bladder-sparing approaches and the current state of bladder cancer care. As such, in the following article, we have focused on not only the rationale for concurrent radiotherapy and hyperthermia, but also the clinical landscape in bladder cancer as a whole.

Radiation oncology in the era of precision medicine

Technological advances and clinical research over the past few decades have given radiation oncologists the capability to personalize treatments for accurate delivery of radiation dose based on clinical parameters and anatomical information. Eradication of gross and microscopic tumours with preservation of health-related quality of life can be achieved in many patients. Two major strategies, acting synergistically, will enable further widening of the therapeutic window of radiation oncology in the era of precision medicine: technology-driven improvement of treatment conformity, including advanced image guidance and particle therapy, and novel biological concepts for personalized treatment, including biomarker-guided prescription, combined treatment modalities and adaptation of treatment during its course.

Characterization of in vitro radiosensitization in mammalian cells using biomathematical modelling: implications for hypofractionated radiotherapy with a combined modality approach

OBJECTIVE

It is unclear whether radiosensitization is beneficial when radiotherapy is administered at a high dose per fraction. The aim of this study was to assess the impact of radiation dose on the effectiveness of a broad range of radiosensitizers.

METHODS

We analyzed 653 pairs of clonogenic survival curves in 285 published articles, in which modifications of radiosensitivity were studied using the colony-forming assay. The modifications of radiosensitivity were arbitrarily classified into 20 classes. The survival curves were fitted to two biomathematical models: the linear-quadratic model and the repair-misrepair (RMR) model.

RESULTS

We found that radiosensitization was predominantly characterized by an increase of the α value (α-sensitization) without an increase of the β value (β-sensitization). A subset analysis revealed that all 20 classes showed significant α-sensitization. In contrast, only oxygen/hypoxic sensitizers (oxygen) and poly(adenosine diphosphate-ribose) polymerase inhibition (PARPi) exhibited β-sensitization. An analysis using the RMR model revealed two major sources of radiosensitization: an increased residual DNA lesion through repair inhibition and a shift from linear repairs to quadratic misrepairs, leading to enhanced lethal chromosomal aberrations.

CONCLUSION

Oxygen and PARPi were found to show β-sensitization, which was favourable for eliciting a comparable degree of sensitization in the higher dose range. Reduced fidelity of the repair was suggested to be a possible mechanism of β-sensitization. Further study targeting β-sensitization is needed to develop a novel combined modality therapy with high-dose-per-fraction radiotherapy.

ADVANCES IN KNOWLEDGE

Radiosensitization can be classified into two groups, α- and β-sensitizations. These two phenomena may stem from distinct underlying mechanisms.

Standardized data collection to build prediction models in oncology: a prototype for rectal cancer

The advances in diagnostic and treatment technology are responsible for a remarkable transformation in the internal medicine concept with the establishment of a new idea of personalized medicine. Inter- and intra-patient tumor heterogeneity and the clinical outcome and/or treatment's toxicity's complexity, justify the effort to develop predictive models from decision support systems. However, the number of evaluated variables coming from multiple disciplines: oncology, computer science, bioinformatics, statistics, genomics, imaging, among others could be very large thus making traditional statistical analysis difficult to exploit. Automated data-mining processes and machine learning approaches can be a solution to organize the massive amount of data, trying to unravel important interaction. The purpose of this paper is to describe the strategy to collect and analyze data properly for decision support and introduce the concept of an 'umbrella protocol' within the framework of 'rapid learning healthcare'.

EGFR targeted therapies and radiation: Optimizing efficacy by appropriate drug scheduling and patient selection

The epidermal growth factor receptor (EGFR) plays an important role in tumor progression and treatment resistance for many types of malignancies including head and neck, colorectal, and nonsmall cell lung cancer. Several EGFR targeted therapies are efficacious as single agents or in combination with chemotherapy. Given the toxicity associated with chemoradiation and poor outcomes seen in several types of cancers, combinations of EGFR targeted agents with or without chemotherapy have been tested in patients receiving radiation. To date, the only FDA approved use of an anti-EGFR therapy in combination with radiation therapy is for locally advanced head and neck cancer. Given the important role EGFR plays in lung and colorectal cancer and the benefit of EGFR inhibition combined with chemotherapy in these disease sites, it is perplexing why EGFR targeted therapies in combination with radiation or chemoradiation have not been more successful. In this review we summarize the clinical findings of EGFR targeted therapies combined with radiation and chemoradiation regimens. We then discuss the interaction between EGFR and radiation including radiation induced EGFR signaling, the effect of EGFR on DNA damage repair, and potential mechanisms of radiosensitization. Finally, we examine the potential pitfalls with scheduling EGFR targeted therapies with chemoradiation and the use of predictive biomarkers to improve patient selection.

Antitumor Effects of MEHD7945A, a Dual-Specific Antibody against EGFR and HER3, in Combination with Radiation in Lung and Head and Neck Cancers

Human epidermal growth factor receptor family members (EGFR, HER2, HER3, and HER4) play important roles in tumorigenesis and response to cancer therapeutics. In this study, we evaluated the capacity of the dual-target antibody MEHD7945A that simultaneously targets EGFR and HER3 to modulate radiation response in lung and head and neck cancer models. Antitumor effects of MEHD7945A in combination with radiation were evaluated in cell culture and tumor xenograft models. Mechanisms that may contribute to increased radiation killing by MEHD7945A, including DNA damage and inhibition of EGFR-HER signaling pathways, were analyzed. Immunohistochemical analysis of tumor xenografts was conducted to evaluate the effect of MEHD7945A in combination with radiation on tumor growth and microenvironment. MEHD7945A inhibited basal and radiation-induced EGFR and HER3 activation resulting in the inhibition of tumor cell growth and enhanced radiosensitivity. MEHD7945A was more effective in augmenting radiation response than treatment with individual anti-EGFR or anti-HER3 antibodies. An increase in DNA double-strand breaks associated γ-H2AX was observed in cells receiving combined treatment with MEHD7945A and radiation. Immunohistochemical staining evaluation in human tumor xenografts showed that MEHD7945A combined with radiation significantly reduced the expression of markers of tumor proliferation and tumor vasculature. These findings reveal the capacity of MEHD7945A to augment radiation response in lung and head and neck cancers. The dual EGFR/HER3-targeting action of MEHD7945A merits further investigation and clinical trial evaluation as a radiation sensitizer in cancer therapy.

Investigation of epothilone B-induced cell death mechanisms in human epithelial cancer cells -in consideration of combined treatment with ionizing radiation

Epothilone B was shown to have promising chemo- and radiosensitizing effects on cells, but the mechanisms underlying cell death remain ambiguous. The aim of the study was to examine selected cell death pathways on the basis of FaDu and A549 cells. Western blot analyses were used for investigation of specific apoptotic markers. Immunofluorescence imaging and flow cytometry were utilized for examination of cell death mechanisms. DNA-staining was used for studying influence of epothilone B on micronucleus rate. We showed that epothilone B can initiate cell death via apoptosis and mitotic catastrophe, but induction of cell death was cell type specific.

Cytotoxic agents and radiation therapy: mechanisms of action and clinical applications

Background

The combination of radiation therapy and chemotherapy is rooted in its ability to help achieve locoregional and systemic control, therefore increasing the overall disease-free survival of patients. Understanding the mechanistic actions of cytotoxic agents and their targets on the cell cycle, as well as the governing pharmacokinetic principles can improve treatment delivery. The adjuvant treatment setting can overcome barriers such as hypoxia and genetically driven treatment resistance.

Purpose

The purpose of this review is to present theoretical frameworks behind the chemoradiation paradigm and to describe current chemoradiation practices in radiation oncology.

Methodology

A review was conducted using the US National Library of Medicine, National Institutes of Health database (PubMed) using the following search keywords: chemoradiation, spatial cooperation, chemotherapeutic agents, pharmacokinetics, anti-vascular agents, tumour vasculature and tumour hypoxia.

Results and conclusions

Current research has reported several rationales for the beneficial combination of radiation and chemotherapy to eradicate oncological diseases. Mechanisms of action and biological approaches are showing that concurrent treatments, as well as novel agents such as anti-vascular and anti-angiogenic agents may benefit improved treatment outcomes by reducing micro hypoxic environments in tumours. In addition, chemotherapy administered in tandem with radiation enhances cell-killing effects by targeting the cell cycle.

SBRT in pancreatic cancer: what is the therapeutic window?

PURPOSE/OBJECTIVE

To analyse outcome and toxicity of stereotactic body radiotherapy (SBRT) in pancreatic cancer (PDAC).

MATERIAL/METHODS

We systematically reviewed full reports on outcome and toxicity transforming prescription doses to equivalent doses of 2 Gy (EQD2) and biological equivalent doses (BED). Pearson product-moment correlation coefficient, regression analysis and Lyman-Kutcher-Burman modelling were used.

RESULTS

Sixteen trials (572 patients) were identified. Local control correlated with dose. Additionally 4 upper gastrointestinal-SBRT trials (149 patients) were included for toxicity analysis. Acute toxicity was mild but late toxicity ⩾G2 was substantial and predominantly gastrointestinal. Late toxicity ⩾G2 and ⩾G3 correlated highly with EQD2/BED after linear (R(2)=0.85 and 0.77, respectively) and Lyman-Kutcher-Burman modelling. Linear regression lines indicated ⩾G2 and ⩾G3 toxicity frequencies of 5% at 65 Gy and 80 Gy EQD2-α/β=3, respectively. A comparison of toxicity with dose constraints for duodenum revealed partly inadequate dose constraints.

CONCLUSION

RESULTS from multiple fraction regimens could be successfully interpreted to estimate toxicity according to EQD2/BED prescription doses, and dose constraints for the duodenum were derived, whereas local control appeared to be less dose-dependent. This analysis may be useful to plan clinical trials for SBRT and hypofractionated radiotherapy in pancreatic cancer.

Biomarkers of treatment toxicity in combined-modality cancer therapies with radiation and systemic drugs: study design, multiplex methods, molecular networks

Organ toxicity in cancer therapy is likely caused by an underlying disposition for given pathophysiological mechanisms in the individual patient. Mechanistic data on treatment toxicity at the patient level are scarce; hence, probabilistic and translational linkages among different layers of data information, all the way from cellular targets of the therapeutic exposure to tissues and ultimately the patient’s organ systems, are required. Throughout all of these layers, untoward treatment effects may be viewed as perturbations that propagate within a hierarchically structured network from one functional level to the next, at each level causing disturbances that reach a critical threshold, which ultimately are manifested as clinical adverse reactions. Advances in bioinformatics permit compilation of information across the various levels of data organization, presumably enabling integrated systems biology-based prediction of treatment safety. In view of the complexity of biological responses to cancer therapy, this communication reports on a “top-down” strategy, starting with the systematic assessment of adverse effects within a defined therapeutic context and proceeding to transcriptomic and proteomic analysis of relevant patient tissue samples and computational exploration of the resulting data, with the ultimate aim of utilizing information from functional connectivity networks in evaluation of patient safety in multimodal cancer therapy.

A systematic review and meta-analysis of clinical trials of bladder-sparing trimodality treatment for muscle-invasive bladder cancer (MIBC)

PURPOSE

Despite the numerous prospective and retrospective studies published during the last 2 decades aiming at testing the safety and the efficacy of trimodality therapy (TMT) as a conservative treatment, an optimal therapeutic strategy has not yet been identified. We made a systematic overview of the 5-year outcomes from 31 trials of combined chemotherapy and radiation (CRT) after transurethral resection of muscle-infiltrating bladder tumours (TURBT), the so-called trimodality therapy. We took into consideration the results of each trial i.e. the rate of complete response (CR), local muscle-invasive local failure (LF), salvage cystectomy (SC), 5-year overall survival (OS) and 5-year bladder intact survival (BIS) from 3315 patients.

RESULTS

About half of the patients were treated with a preliminary induction followed by a consolidation CRT course in CR, or SC in non-CR patients (split treatment). The remaining half of the patients underwent an upfront full-dose CRT course (continuous treatment) with SC reserved to non-CR patients. Excellent results were obtained by trimodality therapy (TMT), with 78% CR, 28% muscle infiltrating LF and 21% SC in patients with MIBC. The 5-year OS and BIS rates were 56% and 42%, respectively. At univariate analysis, CR, and SC rates appeared to be significantly better in the continuous than in the split treatment group. Multivariate analysis confirmed the former regimen as a significant prognostic variables only for CR, while CP-based regimen was a significant prognostic factor for SC. The subgroup analysis revealed a significant improvement in 5-year OS rate of continuous over split treatment in later stage tumours. No relevant benefit was observed with the addition of other drugs to cisplatin (CP) or neo-adjuvant chemotherapy (NATC) to CRT, although, in patients receiving NACT, significantly better CR and OS rates were seen in the continuous than split treatment.

CONCLUSIONS

The results of this overview seem to indicate that TMT is able to produce excellent 5-year OS rates, no matter how it is done (continuous or split). No significant difference in 5-year OS rates could be observed between the two treatment regimens, although the continuous may offer some advantage compared to split treatment in terms of higher CR and, likely lower SC rates. The highest benefit might be achieved in later stage tumours, using a total radiation equivalent dose when delivered in 2Gy/fraction (EQD2) of more than 60Gy in combination with CP based regimes and preceded by 2-3 NACT cycles. Appropriate randomized trials should be addressed to confirm the results of the present review.