Julian Biau

A Preclinical Study Combining the DNA Repair Inhibitor Dbait with Radiotherapy for the Treatment of Melanoma

Melanomas are highly radioresistant tumors, mainly due to efficient DNA double-strand break (DSB) repair. Dbait (which stands for DNA strand break bait) molecules mimic DSBs and trap DNA repair proteins, thereby inhibiting repair of DNA damage induced by radiation therapy (RT). First, the cytotoxic efficacy of Dbait in combination with RT was evaluated in vitro in SK28 and 501mel human melanoma cell lines. Though the extent of RT-induced damage was not increased by Dbait, it persisted for longer revealing a repair defect. Dbait enhanced RT efficacy independently of RT doses. We further assayed the capacity of DT01 (clinical form of Dbait) to enhance efficacy of “palliative” RT (10 × 3 Gy) or “radical” RT (20 × 3 Gy), in an SK28 xenografted model. Inhibition of repair of RT-induced DSB by DT01 was revealed by the significant increase of micronuclei in tumors treated with combined treatment. Mice treated with DT01 and RT combination had significantly better tumor growth control and longer survival compared to RT alone with the “palliative” protocol [tumor growth delay (TGD) by 5.7-fold; median survival: 119 vs 67 days] or the “radical” protocol (TGD by 3.2-fold; median survival: 221 vs 109 days). Only animals that received the combined treatment showed complete responses. No additional toxicity was observed in any DT01-treated groups. This preclinical study provides encouraging results for a combination of a new DNA repair inhibitor, DT01, with RT, in the absence of toxicity. A first-in-human phase I study is currently under way in the palliative management of melanoma in-transit metastases (DRIIM trial).

Colorectal Cancer Metastasis: The DNA Repair Inhibitor Dbait Increases Sensitivity to Hyperthermia and Improves Efficacy of Radiofrequency Ablation

PURPOSE To assess the usefulness of combining hyperthermia with a DNA repair inhibitor (double-strand break bait [Dbait]) and its potential application to radiofrequency ablation (RFA) in a preclinical model of human colorectal cancer. MATERIALS AND METHODS The local ethics committee of animal experimentation approved all investigations. First, the relevance was assessed by studying the survival of four human colorectal adenocarcinoma cell cultures after 1 hour of hyperthermia at 41°C or 43°C with or without Dbait. Human colon adenocarcinoma cells (HT-29) were grafted subcutaneously into nude mice (n = 111). When tumors reached approximately 500 mm(3), mice were treated with Dbait alone (n = 20), sublethal RFA (n = 21), three different Dbait schemes and sublethal RFA (n = 52), or a sham treatment (n = 18). RFA was performed to ablate the tumor center alone. To elucidate antitumor mechanisms, 39 mice were sacrificed for blinded pathologic analysis, including assessment of DNA damage, cell proliferation, and tumor necrosis. Others were monitored for tumor growth and survival. Analyses of variance and log-rank tests were used to evaluate differences. RESULTS When associated with mild hyperthermia, Dbait induced cytotoxicity in all tested colon cancer cell lines. Sublethal RFA or Dbait treatment alone moderately improved survival (median, 40 days vs 28 days for control; P = .0005) but combination treatment significantly improved survival (median, 84 days vs 40 days for RFA alone, P = .0004), with approximately half of the animals showing complete tumor responses. Pathologic studies showed that the Dbait and RFA combination strongly enhances DNA damage and coagulation areas in tumors. CONCLUSION Combining Dbait with RFA sensitizes the tumor periphery to mild hyperthermia and increases RFA antitumor efficacy.

Role of STAT3 in Genesis and Progression of Human Malignant Gliomas

Signal transducer and activator of transcription 3 (STAT3) is aberrantly activated in glioblastoma and has been identified as a relevant therapeutic target in this disease and many other human cancers. After two decades of intensive research, there is not yet any approved STAT3-based glioma therapy. In addition to the canonical activation by tyrosine 705 phosphorylation, concordant reports described a potential therapeutic relevance of other post-translational modifications including mainly serine 727 phosphorylation. Such reports reinforce the need to refine the strategy of targeting STAT3 in each concerned disease. This review focuses on the role of serine 727 and tyrosine 705 phosphorylation of STAT3 in glioma. It explores their contribution to glial cell transformation and to the mechanisms that make glioma escape to both immune control and standard treatment.

STAT3 Serine 727 Phosphorylation: A Relevant Target to Radiosensitize Human Glioblastoma

Radiotherapy is an essential component of glioma standard treatment. Glioblastomas (GBM), however, display an important radioresistance leading to tumor recurrence. To improve patient prognosis, there is a need to radiosensitize GBM cells and to circumvent the mechanisms of resistance caused by interactions between tumor cells and their microenvironment. STAT3 has been identified as a therapeutic target in glioma because of its involvement in mechanisms sustaining tumor escape to both standard treatment and immune control. Here, we studied the role of STAT3 activation on tyrosine 705 (Y705) and serine 727 (S727) in glioma radioresistance. This study explored STAT3 phosphorylation on Y705 (pSTAT3‐Y705) and S727 (pSTAT3‐S727) in glioma cell lines and in clinical samples. Radiosensitizing effect of STAT3 activation down‐modulation by Gö6976 was explored. In a panel of 15 human glioma cell lines, we found that the level of pSTAT3‐S727 was correlated to intrinsic radioresistance. Moreover, treating GBM cells with Gö6976 resulted in a highly significant radiosensitization associated to a concomitant pSTAT3‐S727 down‐modulation only in GBM cell lines that exhibited no or weak pSTAT3‐Y705. We report the constitutive activation of STAT3‐S727 in all GBM clinical samples. Targeting pSTAT3‐S727 mainly in pSTAT3‐Y705‐negative GBM could be a relevant approach to improve radiation therapy.

Avancées thérapeutiques majeures et nouvelles perspectives en onco-hématologie

Hematology Oncology has a rich history including few crucial therapeutic innovations. These were possible because of the evolution of the cell and molecular biology allowing a better understanding of basic mechanisms of cancerogenesis. We propose here to summarize the most important therapeutic innovations since the beginning of Hematology/Oncology history. We also describe evolution of therapeutic strategies themselves. New insights and therapeutic perspectives for next future are also discussed.

Glioblastome du sujet âgé : état de l’art

The incidence of glioblastoma increases with age, with a median age, at diagnosis, of 65 years. Indeed, the optimization of standard of care of elderly glioblastoma patients in an aging population in Western countries becomes crucial. The age remains the main prognostic factor of glioblastoma. Survival among elderly patients is significantly less than among younger patients. The median survival of elderly glioblastoma patients is generally inferior to 6 months. More aggressive tumor behavior, less aggressive treatments, increased toxicity of therapies and more unfavorable clinical factors and comorbidities could explain a higher severity of the disease in the elderly. The balance between treatment efficacy and quality of life is a major focus because of the shorter life expectancy of patients. The standard of care of glioblastoma in elderly patients remains controversial. Large optimal resection, when achievable, should be preferred to biopsy. Survival is longer after adjuvant radiotherapy, either normofractionated over 6-weeks course or hypofractionated over 3-weeks course, for patients with good clinical status. Hypofractionation is often preferred because of shorter procedure. Chemotherapy alone with temozolomide can be proposed to patients with methylated MGMT promoter. A phase III randomized study, testing short-course adjuvant radiotherapy with or without temozolomide in elderly patients with good clinical status, is ongoing.

SynthèseGlioblastome du sujet âgé : état de l’artElderly patients with glioblastoma: State of the art

The incidence of glioblastoma increases with age, with a median age, at diagnosis, of 65 years. Indeed, the optimization of standard of care of elderly glioblastoma patients in an aging population in Western countries becomes crucial. The age remains the main prognostic factor of glioblastoma. Survival among elderly patients is significantly less than among younger patients. The median survival of elderly glioblastoma patients is generally inferior to 6 months. More aggressive tumor behavior, less aggressive treatments, increased toxicity of therapies and more unfavorable clinical factors and comorbidities could explain a higher severity of the disease in the elderly. The balance between treatment efficacy and quality of life is a major focus because of the shorter life expectancy of patients. The standard of care of glioblastoma in elderly patients remains controversial. Large optimal resection, when achievable, should be preferred to biopsy. Survival is longer after adjuvant radiotherapy, either normofractionated over 6-weeks course or hypofractionated over 3-weeks course, for patients with good clinical status. Hypofractionation is often preferred because of shorter procedure. Chemotherapy alone with temozolomide can be proposed to patients with methylated MGMT promoter. A phase III randomized study, testing short-course adjuvant radiotherapy with or without temozolomide in elderly patients with good clinical status, is ongoing.

Global Conservation of Protein Status between Cell Lines and Xenografts

Common preclinical models for testing anticancer treatment include cultured human tumor cell lines in monolayer, and xenografts derived from these cell lines in immunodeficient mice. Our goal was to determine how similar the xenografts are compared with their original cell line and to determine whether it is possible to predict the stability of a xenograft model beforehand. We studied a selection of 89 protein markers of interest in 14 human cell cultures and respective subcutaneous xenografts using the reverse-phase protein array technology. We specifically focused on proteins and posttranslational modifications involved in DNA repair, PI3K pathway, apoptosis, tyrosine kinase signaling, stress, cell cycle, MAPK/ERK signaling, SAPK/JNK signaling, NFκB signaling, and adhesion/cytoskeleton. Using hierarchical clustering, most cell culture-xenograft pairs cluster together, suggesting a global conservation of protein signature. Particularly, Akt, NFkB, EGFR, and Vimentin showed very stable protein expression and phosphorylation levels highlighting that 4 of 10 pathways were highly correlated whatever the model. Other proteins were heterogeneously conserved depending on the cell line. Finally, cell line models with low Akt pathway activation and low levels of Vimentin gave rise to more reliable xenograft models. These results may be useful for the extrapolation of cell culture experiments to in vivo models in novel targeted drug discovery.

Excluding either gross tumor volume or planning target volume from the normal lung volume in lung cancer irradiation: Evaluation of the dosimetric impact.

PURPOSE When evaluating dosimetric parameters predictive of lung toxicity in lung cancer, the total lung volume can be defined to exclude the gross tumor volume (lung-GTV) or to exclude the planning target volume (lung-PTV). The purpose of the study was to evaluate the impact of these 2 types of delineation on the dosimetric parameters V20, V30, and mean lung dose (MLD). METHODS AND MATERIALS We analyzed 69 patients with lung cancer treated with 3-dimensional radiation therapy. Normal lung volume was defined using 2 modalities of delineation: lung-GTV and lung-PTV. The lung volume inside the PTV, but outside the GTV, corresponded to the margins within the lung parenchyma applied to the GTV and the clinical target volume (CTV) to obtain the PTV. This volume (expressed in percentage of total lung volume) increases with the following: (1) the margins (GTV to CTV and CTV to PTV) increase within the lung parenchyma; (2) the GTV increases; and (3) the total lung volume decreases. RESULTS Mean reduction of lung volume was 5.1% (range, 1.4-10.0). With the delineation lung-PTV rather than lung-GTV, the mean reduction was 3.1% (P < 10(-7)), 3.3% (P < 10(-7)), and 2.1 Gy (P < 10(-7)) for V20, V30, and MLD, respectively. These reductions correlated strongly with reduction of lung volume (r(2) range, 0.89-0.96). For 25% of patients having greater reduction of lung volume (high margins, high tumor volume, small lung volume), reduction of V20 ranged from 4.5%-6.3%, reduction of V30 ranged from 4.6%-7.0%, and reduction of MLD ranged from 2.9 Gy-4 Gy. CONCLUSIONS The dosimetric parameters V20, V30, and MLD are reduced with the delineation using lung-PTV rather than lung-GTV. These reductions correlate with lung volume in the PTV and can be significant.

Intraprostatic Fiducials Compared with Bony Anatomy and Skin Marks for Image-Guided Radiation Therapy of Prostate Cancer

Purpose Prostate motion occurs during radiotherapy for localized prostate cancer. We evaluated the input of intraprostatic fiducials for image-guided radiation therapy and compared it with bony anatomy and skin marks. Methods Eleven patients were implanted with three fiducial markers in the prostate. Daily sets of orthogonal kV-kV images were compared with digitally reconstructed radiography. Data were recorded for skin marks, bony anatomy, and fiducial markers. The variations were analyzed along three principal axes (left-right: LR, superoinferior: SI, and anteroposterior: AP). Results A total of 2,417 measures were recorded over 38 fractions of radiotherapy (76 Gy). Fiducial marker movements from bony anatomy were ≤ 5 mm for 84.2% (confidence interval: CI 95%±1.5), 91.3% (CI 95%±1.1), and 99.5% (CI 95%±0.4) of the measures along the AP, SI, and LR axes, respectively. Ninety-five percent of the shifts between a fiducial marker and the bony anatomy were < 8 mm in the AP and SI axes, and < 3 mm in the LR axis. Fiducial marker movements from skin marks were ≤ 5 mm for 64.8% (CI 95%±1.9), 79.2% (CI 95%±1.6), and 87.2% (CI 95%±1.3) of the measures along the AP, SI, and LR axes, respectively. Bony anatomy movements from skin marks were ≤ 5 mm for 84% (CI 95%±1.4), 92% (CI 95%±1.1), and 87% (CI 95%±1.3) of the measurements along the AP, SI, and LR axes, respectively. Conclusion Using fiducial markers provides better accuracy of repositioning of the prostate than using bony anatomy and skin marks for image-guided radiotherapy of prostate cancer.