Oncological Outcomes After Multidisciplinary Management of Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL).

INTRODUCTION: Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is an uncommon type of non-Hodgkin lymphoma, associated with breast implant capsules. Despite improvements in our understanding of BIA-ALCL, communicating the prognosis to patients remains challenging due to limited long-term follow-up data. This has important implications for decision-making, including recommendations for subsequent reconstructive procedures. The aim of this study was to assess the longer-term oncological outcomes of patients receiving multidisciplinary treatment for BIA-ALCL. METHODS: This was a retrospective cohort study of BIA-ALCL patients treated at a tertiary referral unit. The data are presented using simple descriptive statistics. RESULTS: Between 2015 and 2022, 18 BIA-ALCL patients were treated at our institution. The median age at diagnosis was 48.5 (IQR 41-55) years. Ten patients developed BIA-ALCL after cosmetic breast augmentation, and 8 after breast reconstruction following mastectomy for cancer. All patients had a history of textured implant insertion. The median time from first implant surgery to diagnosis was 8.5 (IQR 7-12) years. All patients underwent en-bloc total capsulectomy with implant removal, and 2 received systemic therapy. Fifteen patients had Stage I (IA-IC) disease, 2 had Stage IIA and 1 Stage III BIA-ALCL, based on the TNM classification system. At a median follow-up of 45 (IQR 15-71) months, there were no episodes of local or systemic relapse or death. CONCLUSIONS: Surgical management for BIA-ALCL is sufficient in early-stage disease, and associated with excellent oncological outcomes. This information is reassuring for patients when discussing recurrence risk.

Primary radiotherapy and deep inferior epigastric perforator flap reconstruction for patients with breast cancer (PRADA): a multicentre, prospective, non-randomised, feasibility study.

BACKGROUND: Radiotherapy before mastectomy and autologous free-flap breast reconstruction can avoid adverse radiation effects on healthy donor tissues and delays to adjuvant radiotherapy. However, evidence for this treatment sequence is sparse. We aimed to explore the feasibility of preoperative radiotherapy followed by skin-sparing mastectomy and deep inferior epigastric perforator (DIEP) flap reconstruction in patients with breast cancer requiring mastectomy. METHODS: We conducted a prospective, non-randomised, feasibility study at two National Health Service trusts in the UK. Eligible patients were women aged older than 18 years with a laboratory diagnosis of primary breast cancer requiring mastectomy and post-mastectomy radiotherapy, who were suitable for DIEP flap reconstruction. Preoperative radiotherapy started 3-4 weeks after neoadjuvant chemotherapy and was delivered to the breast, plus regional nodes as required, at 40 Gy in 15 fractions (over 3 weeks) or 42·72 Gy in 16 fractions (over 3·2 weeks). Adverse skin radiation toxicity was assessed preoperatively using the Radiation Therapy Oncology Group toxicity grading system. Skin-sparing mastectomy and DIEP flap reconstruction were planned for 2-6 weeks after completion of preoperative radiotherapy. The primary endpoint was the proportion of open breast wounds greater than 1 cm width requiring a dressing at 4 weeks after surgery, assessed in all participants. This study is registered with ClinicalTrials.gov, NCT02771938, and is closed to recruitment. FINDINGS: Between Jan 25, 2016, and Dec 11, 2017, 33 patients were enrolled. At 4 weeks after surgery, four (12·1%, 95% CI 3·4-28·2) of 33 patients had an open breast wound greater than 1 cm. One (3%) patient had confluent moist desquamation (grade 3). There were no serious treatment-related adverse events and no treatment-related deaths. INTERPRETATION: Preoperative radiotherapy followed by skin-sparing mastectomy and immediate DIEP flap reconstruction is feasible and technically safe, with rates of breast open wounds similar to those reported with post-mastectomy radiotherapy. A randomised trial comparing preoperative radiotherapy with post-mastectomy radiotherapy is required to precisely determine and compare surgical, oncological, and breast reconstruction outcomes, including quality of life. FUNDING: Cancer Research UK, National Institute for Health Research.

HSP90 inhibition sensitizes head and neck cancer to platin-based chemoradiotherapy by modulation of the DNA damage response resulting in chromosomal fragmentation.

BACKGROUND: Concurrent cisplatin radiotherapy (CCRT) is a current standard-of-care for locally advanced head and neck squamous cell carcinoma (HNSCC). However, CCRT is frequently ineffective in patients with advanced disease. It has previously been shown that HSP90 inhibitors act as radiosensitizers, but these studies have not focused on CCRT in HNSCC. Here, we evaluated the HSP90 inhibitor, AUY922, combined with CCRT. METHODS: The ability of AUY922 to sensitize to CCRT was assessed in p53 mutant head and neck cell lines by clonogenic assay. Modulation of the CCRT induced DNA damage response (DDR) by AUY922 was characterized by confocal image analysis of RAD51, BRCA1, 53BP1, ATM and mutant p53 signaling. The role of FANCA depletion by AUY922 was examined using shRNA. Cell cycle checkpoint abrogation and chromosomal fragmentation was assessed by western blot, FACS and confocal. The role of ATM was also assessed by shRNA. AUY922 in combination with CCRT was assessed in vivo. RESULTS: The combination of AUY922 with cisplatin, radiation and CCRT was found to be synergistic in p53 mutant HNSCC. AUY922 leads to significant alterations to the DDR induced by CCRT. This comprises inhibition of homologous recombination through decreased RAD51 and pS1524 BRCA1 with a corresponding increase in 53BP1 foci, activation of ATM and signaling into mutant p53. A shift to more error prone repair combined with a loss of checkpoint function leads to fragmentation of chromosomal material. The degree of disruption to DDR signalling correlated to chromosomal fragmentation and loss of clonogenicity. ATM shRNA indicated a possible rationale for the combination of AUY922 and CCRT in cells lacking ATM function. CONCLUSIONS: This study supports future clinical studies combining AUY922 and CCRT in p53 mutant HNSCC. Modulation of the DDR and chromosomal fragmentation are likely to be analytical points of interest in such trials.

Isolated limb perfusion with biochemotherapy and oncolytic virotherapy combines with radiotherapy and surgery to overcome treatment resistance in an animal model of extremity soft tissue sarcoma.

The management of locally advanced or recurrent extremity sarcoma often necessitates multimodal therapy to preserve a limb, of which isolated limb perfusion (ILP) is a key component. However, with standard chemotherapeutic agents used in ILP, the duration of response is limited. Novel agents or treatment combinations are urgently needed to improve outcomes. Previous work in an animal model has demonstrated the efficacy of oncolytic virotherapy when delivered by ILP and, in this study, we report further improvements from combining ILP-delivered oncolytic virotherapy with radiation and surgical resection. In vitro, the combination of radiation with an oncolytic vaccinia virus (GLV-1h68) and melphalan demonstrated increased cytotoxicity in a panel of sarcoma cell lines. The effects were mediated through activation of the intrinsic apoptotic pathway. In vivo, combinations of radiation, oncolytic virotherapy and standard ILP resulted in delayed tumour growth and prolonged survival when compared with standard ILP alone. However, local disease control could only be secured when such treatment was combined with surgical resection, the timing of which was crucial in determining outcome. Combinations of oncolytic virotherapy with surgical resection and radiation have direct clinical relevance in extremity sarcoma and represent an exciting prospect for improving outcomes in this pathology.

BRAF- and MEK-Targeted Small Molecule Inhibitors Exert Enhanced Antimelanoma Effects in Combination With Oncolytic Reovirus Through ER Stress.

Reovirus type 3 (Dearing) (RT3D) infection is selective for cells harboring a mutated/activated RAS pathway. Therefore, in a panel of melanoma cell lines (including RAS mutant, BRAF mutant and RAS/BRAF wild-type), we assessed therapeutic combinations that enhance/suppress ERK1/2 signaling through use of BRAF/MEK inhibitors. In RAS mutant cells, the combination of RT3D with the BRAF inhibitor PLX4720 (paradoxically increasing ERK1/2 signaling in this context) did not enhance reoviral cytotoxicity. Instead, and somewhat surprisingly, RT3D and BRAF inhibition led to enhanced cell kill in BRAF mutated cell lines. Likewise, ERK1/2 inhibition, using the MEK inhibitor PD184352, in combination with RT3D resulted in enhanced cell kill in the entire panel. Interestingly, TCID50 assays showed that BRAF and MEK inhibitors did not affect viral replication. Instead, enhanced efficacy was mediated through ER stress-induced apoptosis, induced by the combination of ERK1/2 inhibition and reovirus infection. In vivo, combined treatments of RT3D and PLX4720 showed significantly increased activity in BRAF mutant tumors in both immune-deficient and immune-competent models. These data provide a strong rationale for clinical translation of strategies in which RT3D is combined with BRAF inhibitors (in BRAF mutant melanoma) and/or MEK inhibitors (in BRAF and RAS mutant melanoma).

Isolated limb perfusion with melphalan, tumour necrosis factor-alpha and oncolytic vaccinia virus improves tumour targeting and prolongs survival in a rat model of advanced extremity sarcoma.

Isolated limb perfusion (ILP) is a treatment for advanced extremity sarcoma and in-transit melanoma. Advancing this procedure by investigating the addition of novel agents, such as cancer-selective oncolytic viruses, may improve both the therapeutic efficacy of ILP and the tumour-targeted delivery of oncolytic virotherapy. Standard in vitro assays were used to characterise single agent and combinatorial activities of melphalan, tumour necrosis factor-alpha (TNF-α) and Lister strain vaccinia virus (GLV-1h68) against BN175 rat sarcoma cells. An orthotopic model of advanced extremity sarcoma was used to evaluate survival of animals after ILP with combinations of TNF-α, melphalan and GLV-1h68. We investigated the efficiency of viral tumour delivery by ILP compared to intravenous therapy, the locoregional and systemic biodistribution of virus after ILP, and the effect of mode of administration on antibody response. The combination of melphalan and GLV-1h68 was synergistic in vitro. The addition of virus to standard ILP regimens was well tolerated and demonstrated superior tumour targeting compared to intravenous administration. Triple therapy (melphalan/TNF-α/GLV-1h68) resulted in increased tumour growth delay and enhanced survival compared to other treatment regimens. Live virus was recovered in large amounts from perfused regions, but in smaller amounts from systemic organs. The addition of oncolytic vaccinia virus to existing TNF-α/melphalan-based ILP strategies results in survival advantage in an immunocompetent rat model of advanced extremity sarcoma. Virus administered by ILP has superior tumour targeting compared to intravenous delivery. Further evaluation and clinical translation of this approach is warranted.

Targeted gene delivery by free-tissue transfer in oncoplastic reconstruction.

Surgery is the most effective curative treatment for various tumour types. Despite a current preference for conservative surgery, radical excision retains a clearly defined role in modern management of locoregional disease. Extirpative defects are reconstructed routinely using free-tissue transfer from a distant donor site. Although these free flaps currently provide no direct therapeutic benefit, advances in gene-delivery techniques offer the possibility to genetically modify flaps to produce potent targeted treatments with greater anatomical control. Several promising therapeutic strategies, including virus-directed enzyme prodrug therapy, genetic radionuclide therapy, and free-flap radioprotection, have the potential to extend the role of the free flap beyond its immediate goal of restoring form and function to patients, but challenges exist. Work to translate therapeutic free-tissue transfer from preclinical study to clinical use is in progress.

Cost and clinical benefit of imaging surveillance after treatment for breast implant-associated anaplastic large cell lymphoma (BIA-ALCL).

Recent UK guidelines recommend that surveillance imaging should not be offered to patients who have undergone treatment for breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) unless clinically indicated. The aim of this study was to explore the evolving practice at a tertiary referral unit and quantify the direct economic costs (DEC) associated with post-treatment BIA-ALCL routine radiological surveillance prior to adoption of the guidelines. Eleven patients were treated for BIA-ALCL between 2015 and 2020. At a median follow-up of 38 months (IQR 12-47) there were no local or distant relapses. Two patients did not have any radiological surveillance and 1 had follow-up elsewhere. The remaining 8 patients had a combination of positron emission tomography/computed tomography (PET/CT) (n = 10), CT (n = 2), breast ultrasound (n = 6), mammogram (n = 4) and breast magnetic resonance imaging (MRI) (n = 1) as routine imaging follow-up not guided by clinical concerns. Total cost of imaging was £10,396 (€12,257) with a median cost of £1953 (€2304) per patient [IQR £526-2029 (€621-2394)]. This cost could have been saved based on current guidelines recommending no routine surveillance for asymptomatic patients.

A meta-analysis of the efficacy of vascularised lymph node transfer in reducing limb volume and cellulitis episodes in patients with cancer treatment-related lymphoedema.

BACKGROUND: Lymphoedema after cancer treatment is a chronic and disabling complication that presents a significant health care burden during survivorship with limited treatment options. Vascularised lymph node transfer (VLNT) can reconstruct lymphatic flow to reduce limb volumes, but limited higher-order evidence exists to support its effectiveness. AIM: The aim of the study was to systematically review and meta-analyse the effectiveness of VLNT in reducing upper limb (UL) or lower limb (LL) volume and cellulitis episodes in patients with cancer treatment-related lymphoedema (CTRL). METHODS: PubMed, Medline (Ovid) and Embase databases were searched between January 1974 and December 2019. Full-length articles where VLNT was the sole therapeutic procedure for CTRL, reporting volumetric limb, frequency of infection episodes and/or lymphoedema-specific quality-of-life data, were included in a random-effects meta-analysis of circumferential reduction rate (CRR). Methodological quality was assessed using STROBE/CONSORT, and a novel, lymphoedema-specific scoring tool was used to assess lymphoedema-specific methodological reporting. Sensitivity analyses on the site of VLNT harvest and recipient location were performed. RESULTS: Thirty-one studies (581 patients) were eligible for inclusion. VLNT led to significant limb volume reductions in UL (above elbow pooled CRRs [CRRP] = 42.7% [95% confidence interval (CI): 36.5-48.8]; below elbow CRRP = 34.1% [95% CI: 33.0-35.1]) and LL (above knee CRRP = 46.8% [95% CI: 43.2-50.4]; below knee CRRP = 54.6% [95% CI: 39.0-70.2]) CTRL. VLNT flaps from extra-abdominal donor sites were associated with greater volume reductions (CRRP = 49.5% [95% CI: 46.5-52.5]) than those from intra-abdominal donor sites (CRRP = 39.6% [95% CI: 37.2-42.0]) and synchronous autologous breast reconstruction/VLNT flaps (CRRP = 32.7% [95% CI: 11.1-54.4]) (p < 0.05). VLNT was also found to reduce the mean number of cellulitis episodes by 2.1 episodes per year (95% CI: -2.7- -1.4) and increased lymphoedema-specific quality-of-life scores (mean difference in Lymphoedema-Specific Quality of Life (LYMQOL) "overall domain" = +4.26). CONCLUSIONS: VLNT is effective in reducing excess limb volume and cellulitis episodes in both UL and LL lymphoedema after cancer treatment. However, significant heterogeneity exists in outcome reporting, and standardisation of reporting processes is recommended.

Acute Immune Signatures and Their Legacies in Severe Acute Respiratory Syndrome Coronavirus-2 Infected Cancer Patients.

Given the immune system's importance for cancer surveillance and treatment, we have investigated how it may be affected by SARS-CoV-2 infection of cancer patients. Across some heterogeneity in tumor type, stage, and treatment, virus-exposed solid cancer patients display a dominant impact of SARS-CoV-2, apparent from the resemblance of their immune signatures to those for COVID-19+ non-cancer patients. This is not the case for hematological malignancies, with virus-exposed patients collectively displaying heterogeneous humoral responses, an exhausted T cell phenotype and a high prevalence of prolonged virus shedding. Furthermore, while recovered solid cancer patients' immunophenotypes resemble those of non-virus-exposed cancer patients, recovered hematological cancer patients display distinct, lingering immunological legacies. Thus, while solid cancer patients, including those with advanced disease, seem no more at risk of SARS-CoV-2-associated immune dysregulation than the general population, hematological cancer patients show complex immunological consequences of SARS-CoV-2 exposure that might usefully inform their care.

Human fibroblast-macrophage tissue spheroids demonstrate ratio-dependent fibrotic activity for in vitro fibrogenesis model development.

Fibrosis is a pathological accumulation of excessive collagen that underlies many of the most common diseases, representing dysfunction of the essential processes of normal tissue healing. Fibrosis research aims to limit this response without ameliorating the essential role of fibrogenesis in organ function. However, the absence of a realistic in vitro model has hindered investigation into mechanisms and potential interventions because the standard 2D monolayer culture of fibroblasts has limited applicability. We sought to develop and optimize fibrosis spheroids: a scaffold-free three-dimensional human fibroblast-macrophage spheroid system representing an improved benchtop model of human fibrosis. We created, characterized and optimized human fibroblast-only spheroids, demonstrating increased collagen deposition compared to monolayer fibroblasts, while spheroids larger than 300 µm suffered from progressively increasing apoptosis. Next, we improved the spheroid system with the addition of human macrophages to more precisely recapitulate the environment during fibrogenesis, creating a hybrid spheroid system with different ratios of fibroblasts and macrophages ranging from 2 : 1 to 64 : 1. We found that in the hybrid spheroids (particularly the 16 : 1 [F16] ratio) more fibroblasts were activated, with greater macrophage polarization towards a pro-inflammatory M1 phenotype. Hybrid spheroids containing higher ratios of macrophages showed greater macrophage heterogeneity and less fibrogenesis, while low macrophage ratios limited macrophage-induced effects and yielded less collagen deposition. The F16 group also had the highest expression levels of fibrosis-related genes (Col-1a1, Col-3a1 and TGF-ß) and inflammation-related genes (TNF, IL1ß and IL6). IF staining demonstrated that F16 spheroids had the highest levels of αSMA, collagen-1 and collagen-3 deposition among all groups as well as formation of a dense collagen rim surrounding the spheroid. Future studies exploring the greater fibrotic activity of F16 spheroids may provide new mechanistic insights into diseases involving excessive fibrotic activity. Microtissue fibrosis models capable of achieving greater clinical fidelity have the potential to combine the relevance of animal models with the scale, cost and throughput of in vitro testing.

Transhiatal esophagectomy in a high volume institution.

BACKGROUND: The optimal operative approach for carcinoma at the lower esophagus and esophagogastric junction remains controversial. The aim of this study was to assess a single unit experience of transhiatal esophagectomy in an era when the use of systemic oncological therapies has increased dramatically. STUDY DESIGN: Between January 2000 and November 2006, 215 consecutive patients (182 males, 33 females, median age = 65 years) underwent transhiatal esophagectomy; invasive malignancy was detected preoperatively in 188 patients. 90 patients (42%) received neoadjuvant chemotherapy. Prospective data was obtained for these patients and cross-referenced with cancer registry survival data. RESULTS: There were 2 in-hospital deaths (0.9%). Major complications included: respiratory complications in 65 patients (30%), cardiovascular complications in 31 patients (14%) and clinically apparent anastomotic leak in 12 patients (6%). Median length of hospital stay was 14 days. The radicality of resection was inversely related to T stage: an R0 resection was achieved in 98-100% of T0/1 tumors and only 14% of T4 tumors. With a median follow up of 26 months, one and five year survival rates were estimated at 81% and 48% respectively. CONCLUSION: Transhiatal esophagectomy is an effective operative approach for tumors of the infracarinal esophagus and the esophagogastric junction. It is associated with low mortality and morbidity and a five survival rate of nearly 50% when combined with neoadjuvant chemotherapy.

Genetically modified lentiviruses that preserve microvascular function protect against late radiation damage in normal tissues.

Improvements in cancer survival mean that long-term toxicities, which contribute to the morbidity of cancer survivorship, are being increasingly recognized. Late adverse effects (LAEs) in normal tissues after radiotherapy (RT) are characterized by vascular dysfunction and fibrosis causing volume loss and tissue contracture, for example, in the free flaps used for immediate breast reconstruction after mastectomy. We evaluated the efficacy of lentivirally delivered superoxide dismutase 2 (SOD2) overexpression and connective tissue growth factor (CTGF) knockdown by short hairpin RNA in reducing the severity of LAEs in an animal model of free flap LAEs. Vectors were delivered by intra-arterial injection, ex vivo, to target the vascular compartment. LVSOD2 and LVshCTGF monotherapy before irradiation resulted in preservation of flap volume or reduction in skin contracture, respectively. Flaps transduced with combination therapy experienced improvements in both volume loss and skin contracture. Both therapies reduced the fibrotic burden after irradiation. LAEs were associated with impaired vascular perfusion, loss of endothelial permeability, and stromal hypoxia, which were all reversed in the treatment model. Using a tumor recurrence model, we showed that SOD2 overexpression in normal tissues did not compromise the efficacy of RT against tumor cells but appeared to enhance it. LVSOD2 and LVshCTGF combination therapy by targeted, intravascular delivery reduced LAE severities in normal tissues without compromising the efficacy of RT and warrants translational evaluation as a free flap-targeted gene therapy.

A mathematical risk-benefit analysis of composite tissue allotransplantation.

BACKGROUND: Composite tissue allotransplantation (CTA) represents a surgical technology whose risks and benefits are unclear. This is problematic for clinicians with respect to patient selection and counseling, and for policy makers in evaluating its merits. Our analysis represents a mathematical approach to risk and benefit estimation in CTA. METHODS: A Markov model was created to represent clinical and immunological outcomes after CTA. Esthetic outcomes were incorporated into the model by creating a disfigurement-related-disability severity score index based on existing literature. Composite tissue allotransplantation in a 30-year-old male was used as a base case analysis. We compared CTA against autogenous reconstruction as competing strategies. Sensitivity analyses were performed on the effect of preoperative esthetic morbidity and postoperative esthetic outcome. RESULTS: Our base-case showed CTA to be the preferred strategy-conferring a benefit of 4.47 esthetic-outcome-adjusted life years. Sensitivity analyses showed CTA to be the preferred strategy if the preoperative disability severity score was greater than 5, and if the severity score after autogenous reconstruction was greater than 7. CONCLUSION: Our model estimates a theoretical risk-benefit threshold for CTA. The model itself can be refined as clinical experience with CTA grows and can incorporate economic and quality-of-life parameters.

Pathological hangman's fracture after successful renal transplantation.

Renal osteodystrophy and post renal transplantation bone disease are increasingly common causes of pathological fracture. The authors present the first case of a pathological hangman's fracture in a patient after successful renal transplantation. An anterior instrumented C2-C4 fusion was performed.

Oncolytic vaccinia virus combined with radiotherapy induces apoptotic cell death in sarcoma cells by down-regulating the inhibitors of apoptosis.

Advanced extremity melanoma and sarcoma present a significant therapeutic challenge, requiring multimodality therapy to treat or even palliate disease. These aggressive tumours are relatively chemo-resistant, therefore new treatment approaches are urgently required. We have previously reported on the efficacy of oncolytic virotherapy (OV) delivered by isolated limb perfusion. In this report, we have improved therapeutic outcomes by combining OV with radiotherapy. In vitro, the combination of oncolytic vaccinia virus (GLV-1h68) and radiotherapy demonstrated synergistic cytotoxicity. This effect was not due to increased viral replication, but mediated through induction of intrinsic apoptosis. GLV-1h68 therapy downregulated the anti-apoptotic BCL-2 proteins (MCL-1 and BCL-XL) and the downstream inhibitors of apoptosis, resulting in cleavage of effector caspases 3 and 7. In an in vivo ILP model, the combination of OV and radiotherapy significantly delayed tumour growth and prolonged survival compared to single agent therapy. These data suggest that the virally-mediated down-regulation of anti-apoptotic proteins may increase the sensitivity of tumour cells to the cytotoxic effects of ionizing radiation. Oncolytic virotherapy represents an exciting candidate for clinical development when delivered by ILP. Its ability to overcome anti-apoptotic signals within tumour cells points the way to further development in combination with conventional anti-cancer therapies.

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.

Adenovirally delivered enzyme prodrug therapy with herpes simplex virus-thymidine kinase in composite tissue free flaps shows therapeutic efficacy in rat models of glioma.

INTRODUCTION: Free flap gene therapy exploits a novel therapeutic window when viral vectors can be delivered into a flap ex vivo. The authors investigated the therapeutic potential of an adenovirally-delivered thymidine kinase/ganciclovir prodrug system expressed following vector delivery into a free flap. METHODS: The authors demonstrated direct in vitro cytotoxicity by treating a panel of malignant cell lines with the thymidine kinase/ganciclovir system and demonstrated significant cell kill proportional to the multiplicity of infection of adenoviral vector expressing thymidine kinase. Bystander cytotoxicity was demonstrated using conditioned media from producer cells (expressing adenovirally-delivered thymidine kinase and treated with ganciclovir) to demonstrate cytotoxicity in naive tumor cells. The authors investigated the effect of adenoviral vector expressing thymidine kinase/ganciclovir therapy in vivo, using models of microscopic and macroscopic residual disease in a rodent superficial inferior epigastric artery flap model. RESULTS: The authors observed retardation of tumor volume growth in both microscopic (p = 0.0004) and macroscopic (p = 0.0005) residual disease models and prolongation of animal survival. Gene expression studies demonstrated that viral genomic material was found predominantly in flap tissues but declined over time. CONCLUSIONS: The authors describe the utility of virally delivered enzyme/prodrug therapy, using a free flap as a vehicle for delivery. They discuss the merits and limitations of this approach and the unique role of therapeutic free flaps among reconstructive techniques available to the plastic surgeon.