Nanoparticle-Enabled Selective Destruction of Prostate Tumor Using MRI-Guided Focal Photothermal Therapy.

BACKGROUND: The Magnetic Resonance Imaging (MRI)-guided focal laser therapy has shown early promise in Phase 1 trial treating low/intermediate-risk localized prostate cancer (PCa), but the lack of tumor selectivity and low efficiency of heat generation remain as drawbacks of agent-free laser therapy. Intrinsic multifunctional porphyrin-nanoparticles (porphysomes) have been exploited to treat localized PCa by MRI-guided focal photothermal therapy (PTT) with significantly improved efficiency and tumor selectivity over prior methods of PTT, providing an effective and safe alternative to active surveillance or radical therapy. METHODS: The tumor accumulation of porphysomes chelated with copper-64 was determined and compared with the clinic standard (18) F-FDG in an orthotropic PCa mouse model by positron emission tomography (PET) imaging, providing quantitative assessment for PTT dosimetry. The PTT was conducted with MRI-guided light delivery and monitored by MR thermometry, mimicking the clinical protocol. The efficacy of treatment and adverse effects to surround tissues were evaluated by histology analysis and tumor growth in survival study via MRI. RESULTS: Porphysomes showed superior tumor-to-prostate selectivity over (18) F-FDG (6:1 vs. 0.36:1). MR thermometry detected tumor temperature increased to ≥55°C within 2 min (671 nm at 500 mW), but minimal increase in surrounding tissues. Porphysome enabled effective PTT eradication of tumor without damaging adjacent organs in orthotropic PCa mouse model. CONCLUSIONS: Porphysome-enabled MRI-guided focal PTT could be an effective and safe approach to treat PCa at low risk of progression, thus addressing the significant unmet clinical needs and benefiting an ever-growing number of patients who may be over-treated and risk unnecessary side effects from radical therapies. Prostate 76:1169-1181, 2016. © 2016 Wiley Periodicals, Inc.

Nanotexaphyrin: One-Pot Synthesis of a Manganese Texaphyrin-Phospholipid Nanoparticle for Magnetic Resonance Imaging.

The discovery and synthesis of novel multifunctional organic building blocks for nanoparticles is challenging. Texaphyrin macrocycles are capable and multifunctional chelators. However, they remain elusive as building blocks for nanoparticles because of the difficulty associated with synthesis of texaphyrin constructs capable of self-assembly. A novel manganese (Mn)-texaphyrin-phospholipid building block is described, along with its one-pot synthesis and self-assembly into a Mn-nanotexaphyrin. This nanoparticle possesses strong resilience to manganese dissociation, structural stability, in vivo bio-safety, and structure-dependent T1 and T2 relaxivities. Magnetic resonance imaging (MRI) contrast enhanced visualization of lymphatic drainage is demonstrated with respect to proximal lymph nodes on the head and neck VX-2 tumors of a rabbit. Synthesis of 17 additional metallo-texaphyrin building blocks suggests that this novel one-pot synthetic procedure for nanotexaphyrins may lead to a wide range of applications in the field of nanomedicines.

Nanoparticle-enabled, image-guided treatment planning of target specific RNAi therapeutics in an orthotopic prostate cancer model.

The abilities to deliver siRNA to its intended action site and assess the delivery efficiency are challenges for current RNAi therapy, where effective siRNA delivery will join force with patient genetic profiling to achieve optimal treatment outcome. Imaging could become a critical enabler to maximize RNAi efficacy in the context of tracking siRNA delivery, rational dosimetry and treatment planning. Several imaging modalities have been used to visualize nanoparticle-based siRNA delivery but rarely did they guide treatment planning. We report a multimodal theranostic lipid-nanoparticle, HPPS(NIR)-chol-siRNA, which has a near-infrared (NIR) fluorescent core, enveloped by phospholipid monolayer, intercalated with siRNA payloads, and constrained by apoA-I mimetic peptides to give ultra-small particle size (<30 nm). Using fluorescence imaging, we demonstrated its cytosolic delivery capability for both NIR-core and dye-labeled siRNAs and its structural integrity in mice through intravenous administration, validating the usefulness of NIR-core as imaging surrogate for non-labeled therapeutic siRNAs. Next, we validated the targeting specificity of HPPS(NIR)-chol-siRNA to orthotopic tumor using sequential four-steps (in vivo, in situ, ex vivo and frozen-tissue) fluorescence imaging. The image co-registration of computed tomography and fluorescence molecular tomography enabled non-invasive assessment and treatment planning of siRNA delivery into the orthotopic tumor, achieving efficacious RNAi therapy.

Aggregate enhanced trimodal porphyrin shell microbubbles for ultrasound, photoacoustic, and fluorescence imaging.

Microbubbles (MBs) are currently used as ultrasound (US) contrast agents and as delivery vehicles for site-specific US-triggered drug and gene delivery. Multimodal US-based imaging methods have been applied preclinically to assess and validate the effectiveness and fate of MBs in imaging and therapy. Here we present the first intrinsically trimodal MBs by incorporating a dense concentration of porphyrin molecules within a MB shell, enabled by the use of a single porphyrin-lipid component. These MBs possess US, photoacoustic, and fluorescence properties that are demonstrated in solution and in a mouse tumor xenograft model. They also have potential to be extended to other imaging modalities such as magnetic resonance imaging and nuclear imaging.

Porphysome nanovesicles generated by porphyrin bilayers for use as multimodal biophotonic contrast agents.

Optically active nanomaterials promise to advance a range of biophotonic techniques through nanoscale optical effects and integration of multiple imaging and therapeutic modalities. Here, we report the development of porphysomes; nanovesicles formed from self-assembled porphyrin bilayers that generated large, tunable extinction coefficients, structure-dependent fluorescence self-quenching and unique photothermal and photoacoustic properties. Porphysomes enabled the sensitive visualization of lymphatic systems using photoacoustic tomography. Near-infrared fluorescence generation could be restored on dissociation, creating opportunities for low-background fluorescence imaging. As a result of their organic nature, porphysomes were enzymatically biodegradable and induced minimal acute toxicity in mice with intravenous doses of 1,000 mg kg(-1). In a similar manner to liposomes, the large aqueous core of porphysomes could be passively or actively loaded. Following systemic administration, porphysomes accumulated in tumours of xenograft-bearing mice and laser irradiation induced photothermal tumour ablation. The optical properties and biocompatibility of porphysomes demonstrate the multimodal potential of organic nanoparticles for biophotonic imaging and therapy.

Liposomal nanostructures for photosensitizer delivery.

BACKGROUND AND OBJECTIVE: In photodynamic therapy (PDT), photosensitizers are activated by light of a specific wavelength and produce cytotoxic molecules to damage diseased tissues. Most photosensitizers are hydrophobic and easily aggregate in aqueous solution. To maintain their photodynamic activity and to enhance delivery efficiency of photosensitizers, various pharmaceutical carriers and delivery systems have been investigated for photosensitizers. This review will focus on liposomal nanostructures for the delivery of photosensitizing agents. METHODS: The published literature of liposomal structures, formulations, and pharmaceutical applications for photosensitizer delivery was reviewed with the main focus on articles published between 2004 and 2011 after the two excellent reviews by Derycke et al., Adv Drug Deliv Rev 2004:56(1); 17-30 and Chen et al., Expert Opin Drug Deliv 2005:2(3);477-487. Many articles dating back to 1970s were also covered for the purpose of obtaining information about historoical development of liposomal formulations for photosensitizer delivery. The systematic search was performed using several electronic databases, including Pubmed and Medline with the key search terms including PDT, photosensitizer, liposome, nanoparticle, formulation, biodistribution, etc. RESULTS: This review focuses on liposomal nanostructures with an in depth discussion on the liposomal structure, size-related effect on blood circulation and composition of phospholipids. Different active targeting strategies will also be reviewed which serve to improve specific targeting of photosensitizers to diseased tissue. To further enhance the selective release and accumulation of photosensitizers at the targeted tissue, triggered release methods have been developed. Many other liposomal structure-based nanoparticles have been developed for improved delivery efficiency for topical and systemic administration of pharmaceutics. Finally, a new class of phototransducing liposomes called "porphysomes" will also be introduced, which achieves intrinsic multifunctionality together with structure simplicity. CONCLUSION: Liposomes have been proved to be efficient and safe organic carriers for photosensitizers. Multifunctional liposomal formulations, such as porphysome, are further explored for clinic theranostic applications.

Photodynamic therapy enables tumor-specific ablation in preclinical models of thyroid cancer.

The incidence of differentiated thyroid cancer has increased significantly during the last several decades. Surgical resection is the primary treatment for thyroid cancer and is highly effective, resulting in 5-year survival rates greater than 98%. However, surgical resection can result in short- and long-term treatment-related morbidities. Additionally, as this malignancy often affects women less than 40 years of age, there is interest in more conservative treatment approaches and, an unmet need for therapeutic options that minimize the risk of surgery-related morbidities while simultaneously providing an effective cancer treatment. Photodynamic therapy (PDT) has the potential to reduce treatment-related side effects by decreasing invasiveness and limiting toxicity. Owing to multiple advantageous properties of the porphyrin-HDL nanoparticle (PLP) as a PDT agent, including preferential accumulation in tumor, biodegradability and unprecedented photosensitizer packing, we evaluate PLP-mediated PDT as a minimally invasive, tumor-specific treatment for thyroid cancer. On both a biologically relevant human papillary thyroid cancer (K1) mouse model and an anatomically relevant rabbit squamous carcinoma (VX2)-implanted rabbit thyroid model, the intrinsic fluorescence of PLP enabled tracking of tumor preferential accumulation and guided PDT. This resulted in significant and specific apoptosis in tumor tissue, but not surrounding normal tissues including trachea and recurrent laryngeal nerve (RLN). A long-term survival study further demonstrated that PLP-PDT enabled complete ablation of tumor tissue while sparing both the normal thyroid tissue and RLN from damage, thus providing a safe, minimally invasive, and effective alternative to thyroidectomy for thyroid cancer therapies.

Preclinical investigation of folate receptor-targeted nanoparticles for photodynamic therapy of malignant pleural mesothelioma.

Photodynamic therapy (PDT) following lung-sparing extended pleurectomy for malignant pleural mesothelioma (MPM) has been investigated as a potential means to kill residual microscopic cells. High expression levels of folate receptor 1 (FOLR1) have been reported in MPM; therefore, targeting FOLR1 has been considered a novel potential strategy. The present study developed FOLR1­targeting porphyrin-lipid nanoparticles (folate-porphysomes, FP) for the treatment of PDT. Furthermore, inhibition of activated epidermal growth factor (EGFR)-associated survival pathways enhance PDT efficacy. In the present study, these approaches were combined; FP-based PDT was used together with an EGFR-tyrosine kinase inhibitor (EGFR-TKI). The frequency of FOLR1 and EGFR expression in MPM was analyzed using tissue microarrays. Confocal microscopy and a cell viability assay were performed to confirm the specificity of FOLR1­targeting cellular uptake and photocytotoxicity in vitro. In vivo fluorescence activation and therapeutic efficacy were subsequently examined. The effects of EGFR-TKI were also assessed in vitro. The in vivo combined antitumor effect of EGFR-TKI and FP-PDT was then evaluated. The results revealed that FOLR1 and EGFR were expressed in 79 and 89% of MPM samples, respectively. In addition, intracellular uptake of FP corresponded well with FOLR1 expression. When MPM cells were incubated with FP and then irradiated at 671 nm, there was significant in vitro cell death, which was inhibited in the presence of free folic acid, thus suggesting the specificity of FPs. FOLR1 targeting resulted in disassembly of the porphysomes and subsequent fluorescence activation in intrathoracic disseminated MPM tumors, as demonstrated by ex vivo tissue imaging. FP-PDT resulted in significant cellular damage and apoptosis in vivo. Furthermore, the combination of pretreatment with EGFR-TKI and FP-PDT induced a marked improvement of treatment responses. In conclusion, FP-based PDT induced selective destruction of MPM cells based on FOLR1 targeting, and pretreatment with EGFR-TKI further enhanced the therapeutic response.

Cell-Free DNA Kinetics in a Pre-Clinical Model of Head and Neck Cancer.

In cancer patients, circulating tumour-derived DNA (ctDNA) levels imperfectly reflect disease burden apparent on medical imaging. Further evaluation of ctDNA levels over time is needed to better understand the correlation with tumour growth and therapeutic response. We describe ctDNA kinetics within an orthotopic, immunocompetent preclinical rabbit model of local-regionally advanced head and neck squamous cell carcinoma (HNSCC). Monitoring primary tumour and metastatic lymph node volume by computed tomography (CT), we observed a correlation between ctDNA levels and tumour burden. We found that ctDNA detection could precede evidence of tumour on CT. Sensitivity and specificity of ctDNA detection in this model was 90.2% (95% C.I.: 76.9-97.3%) and 85.7% (95% C.I.: 67.3-96.0%), respectively. Rapid tumour growth followed by auto-necrosis and tumour volume contraction produced a spike in ctDNA levels, suggesting that viable tumour cells may be required for sustained ctDNA release. Following surgical resection, both ctDNA and total plasma DNA were correlated with recurrent tumour volume. Our results reveal the complex kinetic behaviour of ctDNA and total plasma DNA upon tumour growth or surgery. This pre-clinical model could be useful for future studies focused on elucidating mechanisms of ctDNA release into the circulation from primary and metastatic sites.

Nanoparticle targeted folate receptor 1-enhanced photodynamic therapy for lung cancer.

OBJECTIVE: Despite modest improvements, the prognosis of lung cancer patients has still remained poor and new treatment are urgently needed. Photodynamic therapy (PDT), the use of light-activated compounds (photosensitizers) is a treatment option but its use has been restricted to central airway lesions. Here, we report the use of novel porphyrin-lipid nanoparticles (porphysomes) targeted to folate receptor 1 (FOLR1) to enhance the efficacy and specificity of PDT that may translate into a minimally-invasive intervention for peripheral lung cancer and metastatic lymph nodes of advanced lung cancer. MATERIALS AND METHODS: The frequency of FOLR1 expression in primary lung cancer and metastatic lymph nodes was first analyzed by human tissue samples from surgery and endobronchial ultrasonography-guided transbronchial needle aspiration (EBUS-TBNA). Confocal fluorescence microscopy was then used to confirm the cellular uptake and fluorescence activation in lung cancer cells, and the photocytotoxicity was evaluated using a cell viability assay. In vivo fluorescence activation and quantification of uptake were investigated in mouse lung orthotopic tumor models, followed by the evaluation of in vivo PDT efficacy. RESULTS: FOLR1 was highly expressed in metastatic lymph node samples from patients with advanced lung cancer and was mainly expressed in lung adenocarcinomas in primary lung cancer. Expression of FOLR1 in lung cancer cell lines corresponded with the intracellular uptake of folate-porphysomes in vitro. When irradiated with a 671nm laser at a dose of 10J/cm2, folate-porphysomes showed marked therapeutic efficacy compared with untargeted porphysomes (28% vs. 83% and 24% vs. 99% cell viability in A549 and SBC5 lung cancer cells, respectively). Systemically-administered folate-porphysomes accumulated in lung tumors with significantly enhanced disease-to-normal tissue contrast. Folate-porphysomes mediated PDT successfully inhibited tumor cell proliferation and activated tumor cell apoptosis. CONCLUSION: Folate-porphysome based PDT shows promise in selectively ablating lung cancer based on FOLR1 expression in these preclinical models.

Multimodal Image-Guided Surgical and Photodynamic Interventions in Head and Neck Cancer: From Primary Tumor to Metastatic Drainage.

PURPOSE: The low survival rate of head and neck cancer (HNC) patients is attributable to late disease diagnosis and high recurrence rate. Current HNC staging has inadequate accuracy and low sensitivity for effective diagnosis and treatment management. The multimodal porphyrin lipoprotein-mimicking nanoparticle (PLP), intrinsically capable of positron emission tomography (PET), fluorescence imaging, and photodynamic therapy (PDT), shows great potential to enhance the accuracy of HNC staging and potentially HNC management. EXPERIMENTAL DESIGN: Using a clinically relevant VX-2 buccal carcinoma rabbit model that is able to consistently develop metastasis to regional lymph nodes after tumor induction, we investigated the abilities of PLP for HNC diagnosis and management. RESULTS: PLPs facilitated accurate detection of primary tumor and metastatic nodes (their PET image signal to surrounding muscle ratios were 10.0 and 7.3, respectively), and provided visualization of the lymphatic drainage from tumor to regional lymph nodes by both preoperative PET and intraoperative fluorescence imaging, allowing the identification of unknown primaries and recurrent tumors. PLP-PDT significantly enhanced cell apoptosis in mouse tumors (73.2% of PLP-PDT group vs 7.1% of PLP alone group) and demonstrated complete eradication of primary tumors and obstruction of tumor metastasis in HNC rabbit model without toxicity in normal tissues or damage to adjacent critical structures. CONCLUSIONS: PLPs provide a multimodal imaging and therapy platform that could enhance HNC diagnosis by integrating PET/computed tomography and fluorescence imaging, and improve HNC therapeutic efficacy and specificity by tailoring treatment via fluorescence-guided surgery and PDT.

Non-invasive Macrophage Tracking Using Novel Porphysome Nanoparticles in the Post-myocardial Infarction Murine Heart.

PURPOSE: We generated a folate-conjugated porphyrin nanoparticle (porphysome) suitable for multimodal non-invasive active macrophage tracking post-myocardial infarction (MI). PROCEDURES: Macrophage uptake of folate-conjugated porphysomes was selective. Folate-porphysome cardiac macrophage tracking was detected in vivo using radioligand and fluorescent imaging. To track post-MI macrophage mobilization, cardiac fluorescence signal in folate-porphysome-injected mice was measured for 9 day post-MI. Active macrophage phenotype was assessed using immunohistochemistry. RESULTS: Heart active macrophage presence peaked on day 1, returned to baseline by day 3, and peaked again on day 7 post-MI. Macrophages were distributed throughout the left ventricle at day 1, but aggregated within scar tissue at day 7. Macrophage phenotype was pro-inflammatory (TNFα(+)) at day 1, whereas scar-resident macrophages expressed anti-inflammatory markers (IL-10, TGFß) at day 7. However, day 7 macrophages outside the scar expressed neither pro- nor anti-inflammatory markers. CONCLUSIONS: We established that folate-porphysomes are suitable for non-invasive imaging of macrophages and used it to investigate active macrophage behavior in the infarcted heart.

An Integrated Nanotechnology-Enabled Transbronchial Image-Guided Intervention Strategy for Peripheral Lung Cancer.

Early detection and efficient treatment modality of early-stage peripheral lung cancer is essential. Current nonsurgical treatments for peripheral lung cancer show critical limitations associated with various complications, requiring alternative minimally invasive therapeutics. Porphysome nanoparticle-enabled fluorescence-guided transbronchial photothermal therapy (PTT) of peripheral lung cancer was developed and demonstrated in preclinical animal models. Systemically administered porphysomes accumulated in lung tumors with significantly enhanced disease-to-normal tissue contrast, as confirmed in three subtypes of orthotopic human lung cancer xenografts (A549, H460, and H520) in mice and in an orthotopic VX2 tumor in rabbits. An in-house prototype fluorescence bronchoscope demonstrated the capability of porphysomes for in vivo imaging of lung tumors in the mucosal/submucosal layers, providing real-time fluorescence guidance for transbronchial PTT. Porphysomes also enhanced the efficacy of transbronchial PTT significantly and resulted in selective and efficient tumor tissue ablation in the rabbit model. A clinically used cylindrical diffuser fiber successfully achieved tumor-specific thermal ablation, showing promising evidence for the clinical translation of this novel platform to impact upon nonsurgical treatment of early-stage peripheral lung cancer. Cancer Res; 76(19); 5870-80. ©2016 AACR.

A PEGylation-Free Biomimetic Porphyrin Nanoplatform for Personalized Cancer Theranostics.

PEGylation (PEG) is the most commonly adopted strategy to prolong nanoparticles' vascular circulation by mitigating the reticuloendothelial system uptake. However, there remain many concerns in regards to its immunogenicity, targeting efficiency, etc., which inspires pursuit of alternate, non-PEGylated systems. We introduced here a PEG-free, porphyrin-based ultrasmall nanostructure mimicking nature lipoproteins, termed PLP, that integrates multiple imaging and therapeutic functionalities, including positron emission tomography (PET) imaging, near-infrared (NIR) fluorescence imaging and photodynamic therapy (PDT). With an engineered lipoprotein-mimicking structure, PLP is highly stable in the blood circulation, resulting in favorable pharmacokinetics and biodistribution without the need of PEG. The prompt tumor intracellular trafficking of PLP allows for rapid nanostructure dissociation upon tumor accumulation to release monomeric porphyrins to efficiently generate fluorescence and photodynamic reactivity, which are highly silenced in intact PLP, thus providing an activatable mechanism for low-background NIR fluorescence imaging and tumor-selective PDT. Its intrinsic copper-64 labeling feature allows for noninvasive PET imaging of PLP delivery and quantitative assessment of drug distribution. Using a clinically relevant glioblastoma multiforme model, we demonstrated that PLP enabled accurate delineation of tumor from surrounding healthy brain at size less than 1 mm, exhibiting the potential for intraoperative fluorescence-guided surgery and tumor-selective PDT. Furthermore, we demonstrated the general applicability of PLP for sensitive and accurate detection of primary and metastatic tumors in other clinically relevant animal models. Therefore, PLP offers a biomimetic theranostic nanoplatform for pretreatment stratification using PET and NIR fluorescence imaging and for further customized cancer management via imaging-guided surgery, PDT, or/and potential chemotherapy.

Porphysomes: Multimodal Nanoparticle for Primary Tumor Delineation and Lymphatic Metastasis Mapping in a Head-and-Neck Cancer Rabbit Model (Adv. Healthcare Mater. 14/2015).

On page 2164, J. Chen, J.C. Irish, G. Zheng, and co-workers show how 64 Cu-porphysome nanoparticles enable superior delineation of neoplastic tissues, metastatic lymph nodes, and vascular drainage on a head and neck cancer orthotopic rabbit model by PET imaging. Their selective fluorescence activation in tumor and metastatic lymph nodes permits intraoperative fluorescence guided surgeries.

Multimodal Nanoparticle for Primary Tumor Delineation and Lymphatic Metastasis Mapping in a Head-and-Neck Cancer Rabbit Model.

64 Cu-porphysome nanoparticles enable superior delineation of neoplastic tissues, metastatic lymph nodes, and vascular drainage on head and neck cancer orthotopic rabbit model using positron emission tomography imaging. Additionally, the nanoparticles exhibit selective fluorescence activation in tumor and metastatic lymph nodes, which permits intraoperative real-time visualization of disease tissues to precisely define surgical margins and prevents collateral damage during surgeries.

In situ conversion of porphyrin microbubbles to nanoparticles for multimodality imaging.

Converting nanoparticles or monomeric compounds into larger supramolecular structures by endogenous or external stimuli is increasingly popular because these materials are useful for imaging and treating diseases. However, conversion of microstructures to nanostructures is less common. Here, we show the conversion of microbubbles to nanoparticles using low-frequency ultrasound. The microbubble consists of a bacteriochlorophyll-lipid shell around a perfluoropropane gas. The encapsulated gas provides ultrasound imaging contrast and the porphyrins in the shell confer photoacoustic and fluorescent properties. On exposure to ultrasound, the microbubbles burst and form smaller nanoparticles that possess the same optical properties as the original microbubble. We show that this conversion is possible in tumour-bearing mice and could be validated using photoacoustic imaging. With this conversion, our microbubble can potentially be used to bypass the enhanced permeability and retention effect when delivering drugs to tumours.

Phototheranostic Porphyrin Nanoparticles Enable Visualization and Targeted Treatment of Head and Neck Cancer in Clinically Relevant Models.

Head and neck cancer is the fifth most common type of cancer worldwide and remains challenging for effective treatment due to the proximity to critical anatomical structures in the head and neck region, which increases the probability of toxicity from surgery and radiotherapy, and therefore emphasizes the importance of maximizing the targeted ablation. We have assessed the effectiveness of porphysome nanoparticles to enhance fluorescence and photoacoustic imaging of head and neck tumors in rabbit and hamster models. In addition, we evaluated the effectiveness of this agent for localized photothermal ablative therapy of head and neck tumors. We have demonstrated that porphysomes not only enabled fluorescence and photoacoustic imaging of buccal and tongue carcinomas, but also allowed for complete targeted ablation of these tumors. The supremacy of porphysome-enabled photothermal therapy over surgery to completely eradicate primary tumors and metastatic regional lymph node while sparing the adjacent critical structures' function has been demonstrated for the first time. This study represents a novel breakthrough that has the potential to revolutionize our approach to tumor diagnosis and treatment in head and neck cancer and beyond.

Targeting-triggered porphysome nanostructure disruption for activatable photodynamic therapy.

Photodynamic therapy (PDT) and photothermal therapy (PTT) possess advantages over the conventional therapies with additional treatment selectivity achieved with local laser irradiation. Comparing to PTT that ablates target tissue via thermal necrosis, PDT induces target cell death via singlet oxygen without damaging the underling connective tissue, thus preserving its biological function. Activatable photosensitizers provide an additional level of treatment selectivity via the disease-associated activation mechanism. In this study, folate-conjugated porphysomes are introduced as targeting-triggered activatable nano-sized beacons for PDT. Porphysomes are reported previously as the most stable and efficient delivery system of porphyrin, but their nanostructure converts the singlet oxygen generation mechanism to thermal ablation mechanism. By folate-receptor-mediated endocytosis, folate-porphysomes are internalized into cells rapidly and resulted in efficient disruption of nanostructures, thus switching back on the photodynamic activity of the densely packed porphyrins for effective PDT. In both in vitro and in vivo studies, folate-porphysomes can achieve folate receptor-selective PDT efficacy, which proves the robustness of targeting-triggered PDT activation of porphysome nanostructure for highly selective tumor ablation. The formulation of porphysomes can be modified with other targeting ligands as activatable photosensitizers for personalized treatment in future.