ATR Inhibition Potentiates the Radiation-induced Inflammatory Tumor Microenvironment.

PURPOSE: ATR inhibitors (ATRi) are in early phase clinical trials and have been shown to sensitize to chemotherapy and radiotherapy preclinically. Limited data have been published about the effect of these drugs on the tumor microenvironment.Experimental Design: We used an immunocompetent mouse model of HPV-driven malignancies to investigate the ATR inhibitor AZD6738 in combination with fractionated radiation (RT). Gene expression analysis and flow cytometry were performed posttherapy. RESULTS: Significant radiosensitization to RT by ATRi was observed alongside a marked increase in immune cell infiltration. We identified increased numbers of CD3+ and NK cells, but most of this infiltrate was composed of myeloid cells. ATRi plus radiation produced a gene expression signature matching a type I/II IFN response, with upregulation of genes playing a role in nucleic acid sensing. Increased MHC I levels were observed on tumor cells, with transcript-level data indicating increased antigen processing and presentation within the tumor. Significant modulation of cytokine gene expression (particularly CCL2, CCL5, and CXCL10) was found in vivo, with in vitro data indicating CCL3, CCL5, and CXCL10 are produced from tumor cells after ATRi + RT. CONCLUSIONS: We show that DNA damage by ATRi and RT leads to an IFN response through activation of nucleic acid-sensing pathways. This triggers increased antigen presentation and innate immune cell infiltration. Further understanding of the effect of this combination on the immune response may allow modulation of these effects to maximize tumor control through antitumor immunity.

The tumour microenvironment after radiotherapy: mechanisms of resistance and recurrence.

Radiotherapy plays a central part in curing cancer. For decades, most research on improving treatment outcomes has focused on modulating radiation-induced biological effects on cancer cells. Recently, we have better understood that components within the tumour microenvironment have pivotal roles in determining treatment outcomes. In this Review, we describe vascular, stromal and immunological changes that are induced in the tumour microenvironment by irradiation and discuss how these changes may promote radioresistance and tumour recurrence. We also highlight how this knowledge is guiding the development of new treatment paradigms in which biologically targeted agents will be combined with radiotherapy.

Donor site morbidity of the medial plantar artery flap studied with gait and pressure analysis.

BACKGROUND: The medial plantar artery flap (MPA) allows transfer of both glabrous (smooth and free from hair) and sensate tissue. It has been suggested that the non-weight bearing instep area of the foot provides tissue for transfer with minimal donor morbidity. However the abductor hallucis muscle and plantar fascia are dissected during flap harvest which may affect foot mechanics. METHODS: Patients were included who had undergone MPA flap harvest and were walking unaided. The majority of the patients studied had problems with soft tissues of their heels rather than trauma as a starting point. Laboratory normals and the patient's contralateral limb were used as controls. Gait and pressure analysis were performed using 3D gait analysis and high resolution pressure analysis. RESULTS: This study included 6 patients, with 5 chronic wounds (4 ipsilateral, 1 contralateral) and 1 traumatic ankle defect. QUESTIONNAIRE RESULTS: Enneking scores: 67.9% return to function; Foot Function Index scores: 39.1% loss of function. GAIT ANALYSIS: Significant differences were seen in kinetic and kinematic data. PRESSURE ANALYSIS: The donor site group had significantly less pressure in the great toe (38.1kPa vs. 78.1kPa, p=0.013), significantly slower transition through the midfoot (445.2ms vs. 352.07ms, p=0.016) and increased impulse in the heel (3.1kPa/s vs. 11.7kPa/s, p=0.038). CONCLUSIONS: This study demonstrates subjective and objective evidence of MPA donor site morbidity. Comparison to other studies looking at gait and pressure changes seen after flap reconstruction of the plantar region suggest that much of this difference may be attributable to ipsilateral reconstruction. As the majority had chronic problems with the soft tissues over the heel some of these biomechanical responses could be related to learned behaviour preoperatively or continued discomfort in the heel pad. Nonetheless it demonstrates accurately the effect of the technique overall on the function of the foot. The changes in the region of the great toe may be solely attributable to MPA harvest. These results suggest that MPA harvest is not free of donor morbidity.

Fasciocutaneous flaps of the subscapular artery axis to reconstruct large extremity defects.

INTRODUCTION: The scapular, parascapular and thoracodorsal artery perforator (TDAP) flaps represent fasciocutaneous flaps derived from the subscapular artery axis. These flaps can be harvested individually or combined as conjoint flaps, tailored to reconstruct a wide variety of defects in the extremities. ANALYSIS AND METHODS: All patients undergoing free-flap reconstruction at North Bristol trust with a fasciocutaneous flap of the subscapular axis from April 2006 until April 2010 were included. This cohort of 45 patients was retrospectively analysed. The Enneking score for return of limb function was used as an outcome measure after reconstruction. Donor-site morbidity analysis was carried out prospectively using Oxford Medical Research Council (MRC) score, Vancouver Scar Scale and disability of arm, shoulder and hand questionnaire (DASH) scores. RESULTS: A total of 45 patients had extremity reconstruction using flaps of the subscapular artery axis following severe limb trauma, often comprising open tibial fractures. A total of 42 patients had lower limb injuries and three had upper limb injuries. All flaps survived. The mean Injury Severity Score (ISS) was 9.3, the mean Enneking score was 27 at 12 months mean follow-up. In the nine conjoint flaps, the mean area of tissue resurfaced was 257 cm2. CONCLUSIONS: In this case series of fasciocutaneous flaps of the subscapular artery axis, we establish that these flaps are robust and versatile. They replace 'like-with-like' and have good patient satisfaction. The donor site can be closed primarily, is discrete and has minimal donor morbidity. The conjoint flaps can be used for reconstruction of very large defects without the need to sacrifice functionally important muscle.