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Introduction: Single domain antibody fragments (sdAbs) are an appealing scaffold for radiopharmaceutical development due to their small size (~15 kDa), high solubility, high stability, and excellent tumor penetration. Previously, we developed NB7 sdAb, which has very high affinity for an epitope on PSMA that is different from those targeted by small molecule PSMA inhibitors. Herein, we evaluated NB7 after radioiodination using [*I]SGMIB (1,3,4-isomer) and iso-[*I]SGMIB (1,3,5-isomer), as well as their 211 At-labeled analogues., Methods: [*I]SGMIB, iso-[*I]SGMIB, [ 211 At]SAGMB, and iso-[ 211 At]SAGMB conjugates of NB7 sdAb were synthesized and their binding affinity, cell uptake and internalization were assessed in PSMA + PC3 PIP and PSMA - PC3 flu cells. Biodistribution studies were performed in mice bearing PSMA + PC3 PIP xenografts. First, a single-label experiment evaluated the tissue distribution of a NB7 bearing a His 6 -tag (NB7H6) and labeled with iso-[ 125 I]SGMIB. Three paired-label experiments then were performed to compare: a) NB7 labeled using [*I]SGMIB and iso-[*I]SGMIB, b) 131 I- vs 211 At-labeled NB7 conjugates and c) [ 125 I]SGMIB-NB7H6 to the small molecule PSMA inhibitor [ 131 I]YF2., Results: All NB7 radioconjugates bound specifically to PSMA with dissociation constants, K d , in the low nM range (1.4-6.4 nM). An initial biodistribution study demonstrated good tumor uptake for iso-[ 125 I]SGMIB-NB7H6 (7.2 ± 1.5 % ID/g at 1 h) and no deleterious effect of the His 6 -tag on renal activity levels, which declined to 3.1 ± 1.1 % ID/g by 4 h. Paired-label biodistribution found no distinction between the two SGMIB isomer NB7 conjugates with the [ 131 I]SGMIB-NB7-to-iso-[ 125 I]SGMIB-NB7 tumor uptake ratios not significantly different from unity: 1.06 ± 0.08 at 1 h, 1.04 ± 0.12 at 4 h, and 1.07 ± 0.09 at 24 h. Both isomer conjugates cleared rapidly from normal tissues and exhibited very low uptake in thyroid, lacrimal and salivary glands. Paired-label biodistribution of [ 131 I]SGMIB-NB7H6 and [ 211 At]SAGMB-NB7H6 demonstrated similar tumor uptake and kidney clearance for the two radioconjugates. However, levels of 211 At in thyroid, stomach, salivary and lacrimal glands were significantly higher (P < 0.05) that those for 131 I suggesting greater dehalogenation for [ 211 At]SAGMB-NB7H6. Finally, co-administration of [ 125 I]SGMIB-NB7H6 and [ 131 I]YF2 demonstrated good tumor uptake for both with considerably more rapid renal clearance for the NB7 radioconjugate., Conclusion: NB7 radioconjugates exhibited good accumulation in PSMA-positive xenografts with rapid clearance from kidney and other normal tissues. We conclude that NB7 is a potentially useful scaffold for developing PSMA-targeted theranostics with different characteristics than current small molecule and antibody-based approaches., Competing Interests: Declaration of competing interest LR and NP have filed a patent application that includes the NB7 single domain antibody fragment. The authors declare that they have no other known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background/aim: The standard treatment for localized prostate cancer involves surgical removal of the prostate with curative intent. However, when tumor cells persist in the operation site, there is high risk of local recurrence and tumor spread, leading to stressful follow-up treatments, impaired quality of life, and reduced overall survival. This study examined photoimmunotherapy (PIT) as a new treatment option for prostate cancer cells., Materials and Methods: We generated conjugates consisting of either a humanized antibody or Fab fragments thereof targeting the prostate specific membrane antigen (PSMA), along with our silicon phthalocyanine photosensitizer dye WB692-CB1. PSMA-expressing prostate cancer cells were incubated with the antibody dye or Fab dye conjugates and cell binding was measured using flow cytometry. Cells were irradiated with varying doses of red light for dye activation, and cytotoxicity was determined by erythrosin B staining and subsequent analysis using a Neubauer counting chamber., Results: Specific cytotoxicity was induced with the antibody dye conjugate in the prostate cancer cells in a light dose-dependent manner. Treatment of the cells with the Fab dye conjugate resulted in lower cytotoxicity, which could be attributed to a reduced binding affinity and a reduced dye uptake of the Fab fragment., Conclusion: Our new antibody dye and Fab dye conjugates offer potential for future intraoperative PIT in patients with localized prostate cancer, with the aim to ensure complete removal of tumor cells from the surgical area, to avoid local recurrence, and to improve clinical outcome., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Introduction: Whilst prostate cancer is the fourth most common cancer globally, effective therapies for patients with advanced disease are lacking. In recent years, interest in using theranostic agents to treat castrate-resistant prostate cancer (CRPC) and metastatic prostate cancer has emerged. Lu-TLX591 monoclonal antibody is a potential agent of significance; however, to date, reports on its toxicity and efficacy have been limited to small clinical trials in heavily pretreated patients. This retrospective study describes the real-world toxicity and efficacy profile of Lu-TLX591., Methods: Eighteen patients received Lu-TLX591 at two private oncology centres in Australia. Patients were eligible if they had CRPC or metastatic prostate cancer and prostate-specific membrane antigen (PSMA)-avid disease confirmed by PSMA-positron emission tomography (PET). Patients received two cycles of Lu-TLX591 monoclonal antibody (177 Lu-DOTA-rosopatamab) each dosed from 1.01-2.85 GBq, 14 days apart. Patient side effects, blood test results and radiology reports were recorded on the patient's electronic medical record (eMR)., Results: Prominent side effects included fatigue (55.6%), anorexia (16.7%), nausea (11.1%), and transfusion reactions (11.1%). All-grade haematological toxicities included lymphopenia (61.1%), anaemia (22.2%), leukopenia (27.8%), neutropenia (27.8%), and thrombocytopenia (27.8%). Grade 4 toxicity included lymphopenia (6.7%) and thrombocytopenia (6.7%). Patients' prostate-specific antigen (PSA) responses were as follows; ≥ 30% PSA decline (27.8%), ≥ 50% PSA decline (11.4%) and any PSA decline (38.9%). Follow-up radiology revealed 54.5% stable disease, 45.4% disease progression and 9.1% disease regression., Conclusion: Lu-TLX591 was safely administered at acceptable toxicity and its efficacy reflects previous clinical trials. Larger studies are required and are underway (NCT04786847; NCT05146973; NCT04876651) to determine Lu-TLX591 effectiveness amongst different prostate cancer populations and compare its efficacy against peptide-based radiopharmaceutical agents., (© 2024. Crown.)

Background: Accurate diagnosis of localized prostate cancer (PCa) is limited by inadequacy of multiparametric (mp) MRI to fully identify and differentiate localized malignant tissue from benign pathologies. Prostate-specific membrane antigen (PSMA) represents an excellent target for molecular imaging. IAB2M, an 85-kD minibody derived from a de-immunized monoclonal antibody directed at the extracellular domain of human PSMA (huJ591), and PSMA-11, a small molecule ligand have been previously tested as probes for visualization of recurrent/metastatic PCa with PET/CT. This pilot, non-randomized trial studied their diagnostic utility in patients (pts) with localized PCa., Methods: Pts planned for radical prostatectomy (RP) were enrolled and underwent mpMRI and PET/CT imaging with 89 Zr-df-IAB2M and/or 68 Ga-PSMA-PET/CT. Image results were read by a radiologist blinded to clinical information and pathology results, mapped and compared to corresponding histopathology findings from all lesions, both clinically significant and nonsignificant. The detection rates of all three imaging modalities were measured and correlated., Results: 20 pts with median age of 64.5 (46-79) years and PSA level of 7.5 (1.6-36.56) ng/ml were enrolled. 19 pts underwent RP and were imaged pre-operatively with 89 Zr-Df-IAB2M PET/CT and mpMRI. Nine of those were imaged using 68 Ga-PSMA-11 as well. Out of 48 intraprostatic lesions verified on surgical pathology, IAB2M PET/CT was able to detect 36 (75%). A similar proportion of pathologically confirmed, clinically significant lesions (22/29, 76%) was detected. IAB2M PET/CT was also able to identify 14/19 (74%) extraprostatic lesions. The performance of mpMRI was inferior, with 24/48 detectable lesions (50%) and 18/29 clinically significant intraprostatic lesions (62%). Compared to the current standard (mpMRI), IAB2M PET/CT had a sensitivity of 88%, specificity 38%, positive predictive value 58%, and accuracy 63%. In 9 pts who underwent Ga-PSMA-11 as well, the latter yielded a detection rate of 70% (14/20), which was also seen in clinically significant lesions (10/14, 71%). Ga-PSMA-11 PET/CT also detected 4/6 (67%) extraprostatic lesions., Conclusions: In this pilot study, the performance of 89 Zr-df-IAB2M was superior to mpMRI and similar to 68 Ga-PSMA-11 PET/CT. The higher detection rate of PSMA-PET supports its use as a diagnostic tool with consequent management change implications in men with localized PCa., (© 2022 Wiley Periodicals LLC.)

Background: Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) may be associated with renal toxicity. We aimed to identify predictive parameters for the development of chronic kidney disease (CKD) in patients with metastatic castration resistant prostate cancer (mCRPC) undergoing RLT., Methods: In 46 mCRPC patients scheduled for Lu-177-PSMA-RLT, pretherapeutic estimated glomerular filtration rate (eGFR [ml/min/1.73 m 2 ]), Tc-99m-mercaptoacetyltriglycine (Tc-99m-MAG3) clearance and baseline Ga-68-PSMA-ligand positron emission tomography (PET)-derived renal cortical uptake and PSMA-tumor volume (TV) were determined. We tested the predictive capability of these parameters and clinical risk factors for the occurrence of CKD (defined as CTCAE vers. 5.0 grade 2 or higher) during follow-up., Results: After 4 ± 3 cycles of RLT average eGFR declined from 76 ± 17 to 72 ± 20 ml/min/1.73 m 2 (p = 0.003). Increased estimated renal radiation dose (eRRD) was significantly associated with renal functional decline (p = 0.008). During follow-up, 16/46 (30.4%) developed CKD grade 2 (no grade 3 or higher). In receiver operating characteristic (ROC) analysis, pretherapeutic eGFR was highly accurate in identifying the occurrence of CKD vs no CKD with an area under the curve (AUC) of 0.945 (p < 0.001; best threshold, 77 ml/min/1.73 m 2 ), followed by Tc-99m-MAG3-derived tubular extraction rate (TER; AUC, 0.831, p < 0.001; best threshold, 200 ml/min/1.73 m 2 ). Renal PET signal (p = 0.751) and PSMA-TV (p = 0.942), however, were not predictive. Kaplan-Meier analyses revealed adverse renal outcome for patients with lower eGFR (p = 0.001) and lower scintigraphy-derived TER (p = 0.009), with pretherapeutic eGFR emerging as the sole predictive parameter in multivariate analysis (p = 0.007)., Conclusion: Serious adverse renal events are not a frequent phenomenon after PSMA-targeted RLT. However, in patients developing moderate CKD after RLT, pretherapeutic eGFR is an independent predictor for renal impairment during follow-up., (© 2021 Authors. The Prostate published by Wiley Periodicals LLC.)

Purpose: The gold nanoparticle (GNP) as a promising theranostic probe has been increasingly studied. The tumor-targeting efficiency of GNPs is crucial to increase the therapeutic ratio. In this study, we developed PSMA-targeted GNPs to enhance GNP uptake in prostate cancer and developed an x-ray fluorescence imaging system to noninvasively monitor and assess GNP delivery., Methods and Materials: For targeted therapy of prostate cancer, anti-prostate-specific membrane antigen (PSMA) antibodies were conjugated onto PEGylated GNPs through 1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) (EDC/NHS) chemistry. In vivo imaging was implemented using an in-house-developed dual-modality computed tomography (CT) and x-ray fluorescence CT (XFCT) system on mice bearing subcutaneous LNCaP prostate tumors. After intravenous administration of GNPs (15 mg/mL, 200 μL), the x-ray fluorescence signals from the tumor were collected at various time points (5 minutes to approximately 30 hours) for GNP pharmacokinetics analysis. At 24 hours after administration, x-ray fluorescence projection (XRFproj) and XFCT imaging were conducted to evaluate the prostate tumor uptake of active- and passive-targeting GNPs. Inductively coupled plasma mass spectrometry analysis was adopted as a benchmark to verify the quantification accuracy of XRFproj/XFCT imaging., Results: Fluorescence microscopic imaging confirmed the enhanced (approximately 4 times) targeting efficiency of PSMA-targeted GNPs in vitro. The pharmacokinetics analysis showed enhanced tumor uptake/retention of PSMA-targeted GNPs and revealed that the peak tumor accumulation appeared at approximately 24 hours after intravenous administration. Both XRFproj and XFCT imaging presented their accuracy in quantifying GNPs within tumors noninvasively. Moreover, XFCT imaging verified its unique capabilities to simultaneously determine the heterogeneous spatial distribution and the concentration of GNPs within tumors in vivo., Conclusions: In conjunction with PSMA-targeted GNPs, XRFproj/XFCT would be a highly sensitive tool for targeted imaging of prostate cancer, benefiting the elucidation of mechanisms of GNP-assisted prostate-cancer therapy., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

We illustrate the development of NaDyF 4 -NaGdF 4 core-shell nanoparticles (NPs) for targeting prostate cancer cells using a preclinical 9.4 T magnetic resonance imaging (MRI) of live animals. The NPs composed of paramagnetic Dy 3+ and Gd 3+ ( T 2 - and T 1 -contrast agents, respectively) demonstrate proton relaxivities of r 1 = 20.2 mM -1 s -1 and r 2 = 32.3 mM -1 s -1 at clinical 3 T and r 1 = 9.4 mM -1 s -1 and r 2 = 144.7 mM -1 s -1 at preclinical 9.4 T. The corresponding relaxivity values per NP are r 1 = 19.4 × 10 5 mM NP -1 s -1 and r 2 = 33.0 × 10 5 mM NP -1 s -1 at 3 T and r 1 = 9.0 × 10 5 mM NP -1 s -1 and r 2 = 147.0 × 10 5 mM NP -1 s -1 at 9.4 T. In vivo active targeting of human prostate tumors grown in nude mice revealed docking of anti-prostate-specific membrane antigen (PSMA) antibody-tagged NPs at tumor sites post-24 h of their intravenous injection. On the other hand, in vivo passive targeting showed preferential accumulation of NPs at tumor sites only within 2 h of their injection, ascribed to the enhanced permeation and retention effect of the tumor. A biodistribution study employing the harvested organs of mice, post-24 h injection of NPs, quantified active targeting as nearly twice as efficient as passive targeting. These outcomes provide potential opportunities for noninvasive diagnosis using NaDyF 4 -NaGdF 4 core-shell NPs for target-specific MRI.

Background: Therapeutic options currently available for metastatic castration-resistant prostate cancer (mCRPC) do not extend median overall survival >6 months. Therefore, the development of novel and effective therapies for mCRPC represents an urgent medical need. T cell engagers (TCEs) have emerged as a promising approach for the treatment of mCRPC due to their targeted mechanism of action. However, challenges remain in the clinic due to the limited efficacy of TCEs observed thus far in solid tumors as well as the toxicities associated with cytokine release syndrome (CRS) due to the usage of high-affinity anti-CD3 moieties such as OKT3., Methods: Using genetically engineered transgenic rats (UniRat and OmniFlic) that express fully human IgG antibodies together with an NGS-based antibody discovery pipeline, we developed TNB-585, an anti-CD3xPSMA TCE for the treatment of mCRPC. TNB-585 pairs a tumor-targeting anti-PSMA arm together with a unique, low-affinity anti-CD3 arm in bispecific format. We tested TNB-585 in T cell-redirected cytotoxicity assays against PSMA + tumor cells in both two-dimensional (2D) cultures and three-dimensional (3D) spheroids as well as against patient-derived prostate tumor cells. Cytokines were measured in culture supernatants to assess the ability of TNB-585 to induce tumor killing with low cytokine release. TNB-585-mediated T cell activation, proliferation, and cytotoxic granule formation were measured to investigate the mechanism of action. Additionally, TNB-585 efficacy was evaluated in vivo against C4-2 tumor-bearing NCG mice., Results: In vitro, TNB-585 induced activation and proliferation of human T cells resulting in the killing of PSMA + prostate tumor cells in both 2D cultures and 3D spheroids with minimal cytokine release and reduced regulatory T cell activation compared with a positive control antibody that contains the same anti-PSMA arm but a higher affinity anti-CD3 arm (comparable with OKT3). In addition, TNB-585 demonstrated potent efficacy against patient-derived prostate tumors ex vivo and induced immune cell infiltration and dose-dependent tumor regression in vivo., Conclusions: Our data suggest that TNB-585, with its low-affinity anti-CD3, may be efficacious while inducing a lower incidence and severity of CRS in patients with prostate cancer compared with TCEs that incorporate high-affinity anti-CD3 domains., Competing Interests: Competing interests: All authors except AS, SK, and LF were employees of Teneobio, Inc with equity interests when the reported work was conducted. LF and RD are consultants of Teneobio, Inc., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Prostate cancer (PCa) is the second most common cancer in men, causing more than 300,000 deaths every year worldwide. Due to their superior cell-killing ability and the relative simplicity of their preparation, immunotoxin molecules have great potential in the clinical treatment of cancer, and several such molecules have been approved for clinical application. In this study, we adopted a relatively simple strategy based on a single-domain antibody (sdAb) and an improved Pseudomonas exotoxin A (PE) toxin (PE24X7) to prepare a safer immunotoxin against prostate-specific membrane antigen (PSMA) for PCa treatment. The designed anti-PSMA immunotoxin, JVM-PE24X7, was conveniently prepared in its soluble form in an Escherichia coli ( E. coli ) system, avoiding the complex renaturation process needed for immunotoxin preparation by the conventional strategy. The product was very stable and showed a very strong ability to bind the PSMA receptor. Cytotoxicity assays showed that this molecule at a very low concentration could kill PSMA-positive PCa cells, with an EC 50 value (concentration at which the cell viability decreased by 50%) of 15.3 pM against PSMA-positive LNCaP cells. Moreover, this molecule showed very good killing selectivity between PSMA-positive and PSMA-negative cells, with a selection ratio of more than 300-fold. Animal studies showed that this molecule at a very low dosage (5 × 0.5 mg/kg once every three days) completely inhibited the growth of PCa tumors, and the maximum tolerable dose (MTD) was more than 15 mg/kg, indicating its very potent tumor-treatment ability and a wide therapeutic window. Use of the new PE toxin, PE24X7, as the effector moiety significantly reduced off-target toxicity and improved the therapeutic window of the immunotoxin. The above results demonstrate that the designed anti-PSMA immunotoxin, JVM-PE24X7, has good application value for the treatment of PCa.

Purpose: Metastatic castration-resistant prostate cancer (mCRPC) remains a disease with high unmet medical need, as most patients do not achieve durable response with available treatments. Prostate-specific membrane antigen (PSMA) is a compelling target for mCRPC. It is highly expressed by primary and metastatic prostate cancer cells, with increased expression after progression on androgen deprivation therapy., Experimental Design: We developed AMG 160, a half-life extended, bispecific T-cell engager immuno-oncology therapy that binds PSMA on prostate cancer cells and cluster of differentiation 3 on T cells for treatment of mCRPC. AMG 160 was evaluated in vitro and in mCRPC xenograft models. AMG 160 tolerability was assessed in nonhuman primates (NHP). AMG 160 activity as monotherapy and in combination with a PSMA-imaging agent, novel hormonal therapy, and immune checkpoint blockade was evaluated., Results: AMG 160 induces potent, specific killing of PSMA-expressing prostate cancer cell lines in vitro , with half-maximal lysis of 6-42 pmol/L. In vivo , AMG 160 administered weekly at 0.2 mg/kg engages T cells administered systemically and promotes regression of established 22Rv-1 mCRPC xenograft tumors. AMG 160 is compatible with the imaging agent gallium 68-labeled PSMA-11, and shows enhanced cytotoxic activity when combined with enzalutamide or an anti-programmed death-1 antibody. AMG 160 exhibits an extended half-life and has an acceptable safety profile in NHPs., Conclusions: The preclinical characterization of AMG 160 highlights its potent antitumor activity in vitro and in vivo , and its potential for use with known diagnostic or therapeutic agents in mCRPC. These data support the ongoing clinical evaluation of AMG 160 in patients with mCRPC. See related commentary by Kamat et al., p. 2675 ., (©2021 American Association for Cancer Research.)

Background: Chimeric antigen receptor (CAR) T cells are effective in B-cell malignancies. However, heterogeneous antigen expression and antigen loss remain important limitations of targeted immunotherapy in solid tumors. Therefore, targeting multiple tumor-associated antigens simultaneously is expected to improve the outcome of CAR-T cell therapies. Due to the instability of single-chain variable fragments, it remains challenging to develop the simultaneous targeting of multiple antigens using traditional single-chain fragment variable (scFv)-based CARs., Methods: We used Humabody V H domains derived from a transgenic mouse to obtain fully human prostate-specific membrane antigen (PSMA) V H and mesothelin (MSLN) V H sequences and redirect T cell with V H based-CAR. The antitumor activity and mode of action of PSMA V H and MSLN V H were evaluated in vitro and in vivo compared with the traditional scFv-based CARs., Results: Human V H domain-based CAR targeting PSMA and MSLN are stable and functional both in vitro and in vivo. V H modules in the bispecific format are capable of binding their specific target with similar affinity as their monovalent counterparts. Bispecific CARs generated by joining two human antibody V H domains can prevent tumor escape in tumor with heterogeneous antigen expression., Conclusions: Fully human antibody V H domains can be used to generate functional CAR molecules, and redirected T cells elicit antitumoral responses in solid tumors at least as well as conventional scFv-based CARs. In addition, V H domains can be used to generate bispecific CAR-T cells to simultaneously target two different antigens expressed by tumor cells, and therefore, achieve better tumor control in solid tumors., Competing Interests: Competing interests: GD has sponsored research agreements with Bluebird Bio, Cell Medica, and Bellicum Pharmaceutical. GD serves on the scientific advisory board of MolMed and Bellicum Pharmaceutical. CJ and BM are employees of Crescendo Biologics Ltd., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)

Synthetic small molecules that redirect endogenous antibodies to target cells are promising drug candidates because they overcome the potential shortcomings of therapeutic antibodies, such as immunogenicity and the need for intravenous delivery. Previously, we reported a novel class of bispecific molecules targeting the antibody Fc region and folate receptor, named Fc-binding antibody-recruiting molecules (Fc-ARMs). Fc-ARMs can theoretically recruit most endogenous antibodies, inducing antibody-dependent cell-mediated cytotoxicity (ADCC) to eliminate cancer cells. Herein, we describe new Fc-ARMs that target prostate cancer (Fc-ARM-Ps). Fc-ARM-Ps recruited antibodies to cancer cells expressing prostate-specific membrane antigen but did so with lower efficiency compared with Fc-ARMs targeting the folate receptor. Upon recruitment by Fc-ARM-P, defucosylated antibodies efficiently activated natural killer cells and induced ADCC, whereas antibodies with intact N-glycans did not. The results suggest that the affinity between recruited antibodies and CD16a, a type of Fc receptor expressed on immune cells, could be a key factor controlling immune activation in the Fc-ARM strategy., (© 2020 Wiley-VCH GmbH.)

Aim:  We report results of a first-in-human study of pasotuxizumab, a PSMA bispecific T-cell engager (BiTE ® ) immune therapy mediating T-cell killing of tumor cells in patients with advanced castration-resistant prostate cancer. Patients & methods: We assessed once-daily subcutaneous (SC) pasotuxizumab. All SC patients developed antidrug antibodies; therefore, continuous intravenous (cIV) infusion was assessed. Results:  A total of 47 patients received pasotuxizumab (SC: n = 31, 0.5-172 μg/d; cIV: n = 16, 5-80 μg/d). The SC maximum tolerated dose was 172.0 μg/d. A sponsor change stopped the cIV cohort early; maximum tolerated dose was not determined. PSA responders occurred (>50% PSA decline: SC, n = 9; cIV, n = 3), including two long-term responders. Conclusion: Data support pasotuxizumab safety in advanced castration-resistant prostate cancer and represent evidence of BiTE monotherapy efficacy in solid tumors. Clinical trial registration: NCT01723475 (ClinicalTrials.gov).

Prostate-Specific Membrane Antigen (PSMA) is an established biomarker for the imaging and experimental therapy of prostate cancer (PCa), as it is strongly upregulated in high-grade primary, androgen-independent, and metastatic lesions. Here, we report on the development and functional characterization of recombinant single-chain Fv (scFv) and Fab fragments derived from the 5D3 PSMA-specific monoclonal antibody (mAb). These fragments were engineered, heterologously expressed in insect S2 cells, and purified to homogeneity with yields up to 20 mg/L. In vitro assays including ELISA, immunofluorescence and flow cytometry, revealed that the fragments retain the nanomolar affinity and single target specificity of the parent 5D3 antibody. Importantly, using a murine xenograft model of PCa, we verified the suitability of fluorescently labeled fragments for in vivo imaging of PSMA-positive tumors and compared their pharmacokinetics and tissue distribution to the parent mAb. Collectively, our data provide an experimental basis for the further development of 5D3 recombinant fragments for future clinical use.

Due to the technical innovations in generating bispecific antibodies (BsAbs) in recent years, BsAbs have become important reagents for diagnostic and therapeutic applications. However, the difficulty of producing a heterodimer consisting of two different arms with high yield and purity constituted a major limitation for their application in academic and clinical settings. Here, we describe a novel Fc-containing BsAb format (Fab × sdAb-Fc) composed of a conventional antigen-binding fragment (Fab), and a single domain antibody (sdAb), which avoids heavy-light chain mis-pairing during antibody assembly. In this study, the Fab x sdAb-Fc BsAbs were efficiently produced by three widely used heavy-heavy chain heterodimerization methods: Knobs-into-holes (KIH), Charge-pairs (CP) and controlled Fab-arm exchange (cFAE), respectively. The novel Fab x sdAb-Fc format provided a rapid and efficient strategy to generate BsAb with high purity and a unique possibility to further purify desired BsAbs from undesired antibodies based on molecular weight (MW). Compared to conventional BsAb formats, the advantages of Fab x sdAb-Fc format may thus provide a straightforward opportunity to apply bispecific antibody principles to research and development of novel targets and pathways in diseases such as cancer and autoimmunity., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

The repertoire of methods for the detection and chemotherapeutic treatment of prostate cancer (PCa) is currently limited. Prostate-specific membrane antigen (PSMA) is overexpressed in PCa tumors and can be exploited for both imaging and drug delivery. We developed and characterized four nanobodies that present tight and specific binding and internalization into PSMA + cells and that accumulate specifically in PSMA + tumors. We then conjugated one of these nanobodies to the cytotoxic drug doxorubicin, and we show that the conjugate internalizes specifically into PSMA + cells, where the drug is released and induces cytotoxic activity. In vivo studies show that the extent of tumor growth inhibition is similar when mice are treated with commercial doxorubicin and with a 42-fold lower amount of the nanobody-conjugated doxorubicin, attesting to the efficacy of the conjugated drug. These data highlight nanobodies as promising agents for the imaging of PCa tumors and for the targeted delivery of chemotherapeutic drugs.

The clinical translation of theranostic 177 Lu-radiopharmaceuticals based on inhibitors of the prostate-specific membrane antigen (PSMA) has demonstrated positive clinical responses in patients with advanced prostate cancer (PCa). However, challenges still remain, particularly regarding their pharmacokinetic and dosimetric properties. We developed a potential PSMA-immunotheranostic agent by conjugation of a single-chain variable fragment of the IgGD2B antibody (scFvD2B) to DOTA, to obtain a 177 Lu-labelled agent with a better pharmacokinetic profile than those previously reported. The labelled conjugated 177 Lu-scFvD2B was obtained in high yield and stability. In vitro, 177 Lu-scFvD2B disclosed a higher binding and internalization in LNCaP (PSMA-positive) compared to PC3 (negative control) human PCa cells. In vivo studies in healthy nude mice revealed that 177 Lu-scFvD2B present a favorable biokinetic profile, characterized by a rapid clearance from non-target tissues and minimal liver accumulation, but a slow wash-out from kidneys. Micro-SPECT/CT imaging of mice bearing pulmonary microtumors evidenced a slow uptake by LNCaP tumors, which steadily rose up to a maximum value of 3.6 SUV at 192 h. This high and prolonged tumor uptake suggests that 177 Lu-scFvD2B has great potential in delivering ablative radiation doses to PSMA-expressing tumors, and warrants further studies to evaluate its preclinical therapeutic efficacy.

Objective : Chimeric antigen receptor T (CAR-T) cell therapy has demonstrated an unprecedented therapeutic efficacy in hematological malignancies; however, its effectiveness in solid tumors remains elusive. In order to enable CAR-T cells more effective to solid tumors, a inverted chimeric cytokine receptor (ICR) was designed, which is consists of the TGF-β extracellular domain, IL-7 receptor intracellular domain, and co-expression on CAR-T cells. Materials and Methods : We selected prostate specific membrane antigen (PSMA) as a target for CAR-T cells, constructed corresponding effector cells, and verified the anti-tumor activity of this enhanced PSMA-CAR-T cell by a series of repeated target cell stimulation experiments in vitro and the anti-tumor capabilities by using mice xenograft model in vivo. Results : In vitro experiments showed that co-expression of ICR could significantly enhance sustained anti-tumor capabilities of PSMA-CAR-T cells. Moreover, in vivo experiments also confirmed that the enhanced PSMA-CAR-T cells exhibited significant superior anti-tumor capabilities and could prolong the survival time in the xenograft and PDX models of prostate cancer. Conclusions : PSMA-CAR-T cells co-expressing ICR can be envisaged as a new therapeutic strategy for prostate cancer and support the translation of this enhanced approach in the clinical setting.

The management of men with prostate cancer (PCa) with biochemical recurrence following local definitive therapy remains controversial. Early use of androgen deprivation therapy (ADT) leads to significant side effects. Developing an alternative, clinically effective, and well-tolerated therapy remains an unmet clinical need. INO-5150 is a synthetic DNA therapy that includes plasmids encoding for prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA), and INO-9012 is a synthetic DNA plasmid encoding for interleukin-12 (IL-12). This phase 1/2, open-label, multi-center study enrolled men with PCa with rising PSA after surgery and/or radiation therapy. Patients were enrolled into one of four treatment arms: arm A, 2 mg of INO-5150; arm B, 8.5 mg of INO-5150; arm C, 2 mg of INO-5150 + 1 mg of INO-9012; and arm D, 8.5 mg of INO-5150 + 1 mg of INO-9012. Patients received study drug with electroporation on day 0 and on weeks 3, 12, and 24, and they were followed for up to 72 weeks. Sixty-two patients were enrolled. Treatment was well tolerated. 81% (50/62) of patients completed all visits. 85% (53/62) remained progression-free at 72 weeks. PSA doubling time (PSADT) was increased when assessed in patients with day 0 PSADT ≤12 months. Immunogenicity was observed in 76% (47/62) of patients by multiple assessments. Analysis indicated that CD38 and perforin co-positive CD8 T cell frequency correlated with attenuated PSA rise (p = 0.05, n = 50)., (Copyright © 2020 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.)

Imaging mass cytometry (IMC) is an emerging imaging technology that exploits the multiplexed analysis capabilities of the CyTOF mass cytometer to make spatially resolved measurements for tissue sections. In a comprehensive view of tissue composition and marker distribution, recent developments of IMC require highly sensitive, multiplexed assays. Approaching the sensitivity of the IMC technique, we designed a novel type of biocompatible metal-labeled aptamer nanoprobe (MAP), named 167 Er-A10-3.2. The small molecular probe was synthesized by conjugating 167 Er-polymeric pentetic acid ( 167 Er-DTPA) with an RNA aptamer A10-3.2. For demonstration, 167 Er-A10-3.2 was applied for observing protein spatial distribution on prostatic epithelium cell of paraffin embedded Prostatic adenocarcinoma (PaC) tissue sections by IMC technology. The 167 Er-A10-3.2 capitalizes on the ability of the aptamer to specifically bind target cancer cells as well as the small size of 167 Er-A10-3.2 can accommodate multiple aptamer binding antigen labeled at high density. The detection signal of 167 Er-A10-3.2 probe was 3-fold higher than that of PSMA antibody probe for a targeted cell under lower temperature epitope retrieval (37 °C) of PaC tissue. Furthermore, we successfully demonstrated the simultaneously staining ability of aptamer probes in IMC analysis. The successful imaging acquisition using aptamers probes in IMC technology may offer opportunity for the diagnosis of malignancies in the future.

Patients with hematologic cancers have improved outcomes after treatment with bispecific antibodies that bind to CD3 on T cells and that redirect T cells toward cancer cells. However, clinical benefit against solid tumors remains to be shown. We made a bispecific antibody that targets both the common prostate tumor-specific antigen PSMA and CD3 (PMSAxCD3) and provide evidence for tumor inhibition in several preclinical solid tumor models. Mice expressing the human extracellular regions of CD3 and PSMA were generated to examine antitumor efficacy in the presence of an intact immune system and PSMA expression in normal tissues. PSMAxCD3 accumulated in PSMA-expressing tissues and tumors as detected by immuno-PET imaging. Although PSMAxCD3 induced T-cell activation and showed antitumor efficacy in mice with low tumor burden, PSMAxCD3 lost efficacy against larger solid tumors, mirroring the difficulty of treating solid tumors in the clinic. Costimulatory receptors can enhance T-cell responses. We show here that costimulation can enhance the antitumor efficacy of PSMAxCD3. In particular, 4-1BB stimulation in combination with PSMAxCD3 enhanced T-cell activation and proliferation, boosted efficacy against larger tumors, and induced T-cell memory, leading to durable antitumor responses. The combination of CD3 bispecific antibodies and anti-4-1BB costimulation represents a therapeutic approach for the treatment of solid tumors., (©2020 American Association for Cancer Research.)

Context: Accurate staging of high-risk localised, advanced, and metastatic prostate cancer is becoming increasingly more important in guiding local and systemic treatment. Gallium-68 prostate-specific membrane antigen (PSMA) positron emission tomography (PET) has increasingly been utilised globally to assess the local and metastatic burden of prostate cancer, typically in biochemically recurrent or advanced disease. Following our previous meta-analysis, a high-volume series has been reported highlighting the utility of 68 Ga-PSMA PET in this setting., Objective: To perform a systematic review and meta-analysis to update reported predictors of positive 68 Ga-PSMA PET according to prior therapy and proportion of positivity in various anatomical locations with sensitivity and specificity profiles., Evidence Acquisition: We performed critical reviews of MEDLINE, EMBASE, ScienceDirect, Cochrane Libraries, and Web of Science databases in July 2018 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Quality assessment was performed using Quality Assessment if Diagnostic Accuracy Studies-2 tool. Meta-analyses of proportions were performed using a random-effect model. Summary sensitivity and specificity values were obtained by fitting bivariate hierarchical regression models., Evidence Synthesis: A total of 37 articles including 4790 patients were analysed. For patients with biochemical recurrence, positive 68 Ga-PSMA PET scans increased with higher pre-PET prostate-specific antigen (PSA) levels. For PSA categories 0-0.19, 0.2-0.49, 0.5-0.99, 1-1.99, and ≥2ng/ml, the percentages of positive scans were 33%, 45%, 59%, 75%, and 95%, respectively. No significant differences in positivity were noted between Gleason sums ≤7 and ≥8. Significant differences in positivity after biochemical recurrence in the prostate bed were noted between radical prostatectomy (22%) and radiotherapy (52%) patients. On per-node analysis, high sensitivity (75%) and specificity (99%) were observed., Conclusions: Ga-68-PSMA PET improves detection of metastases with biochemical recurrence, particularly at low pre-PET PSA levels of >0.2ng/ml (33%) and 0.2-0.5ng/ml (45%). Ga-68-PSMA-PET produces favourable sensitivity and specificity profiles on meta-analysis of pooled data. This analysis highlights different anatomic patterns of metastatic spread according to PSMA PET in the primary and biochemically recurrent settings., Patient Summary: Gallium-68 prostate-specific membrane antigen positron emission tomography is now an established imaging technique that has been developed in response to inadequacies in standard of care imaging modalities to improve the detection of metastatic disease in prostate cancer, particularly in the setting of disease recurrence. To date, this imaging modality in the setting of primary staging is controversial, given the paucity of data. In light of the growing body of evidence, we summarised the data to date to provide clinicians with an overview of this imaging modality., (Copyright © 2019. Published by Elsevier B.V.)

Background: Recently, modification of T cells with chimeric antigen receptor (CAR) has been an attractive approach for adoptive immunotherapy of cancers. Typically, CARs contain a single-chain variable domain fragment (scFv). Most often, scfvs are derived from a monoclonal antibody of murine origin and may be a trigger for host immune system that leads to the T-cell clearance. Nanobody is a specific antigen-binding fragment derived from camelid that has great homology to human VH and low immunogenic potential. Therefore, in this study, nanobody was employed instead of scFv in CAR construct., Methods: In this study, a CAR was constructed based on a nanobody against PSMA (NBPII-CAR). At first, Jurkat cells were electroporated with NBPII-CAR, and then flow cytometry was performed for NBPII-CAR expression. For functional analysis, CAR T cells were co-cultured with prostate cancer cells and analyzed for IL-2 secretion, CD25 expression, and cell proliferation., Results: Flow cytometry results confirmed the expression of NBPII-CAR on the transfected Jurkat cells. Our data showed the specificity of engineered Jurkat cells against prostate cancer cells by not only increasing the IL-2 cytokine (about 370 pg/ml) but also expressing the T-cell activation marker CD25 (about 30%). In addition, proliferation of engineered Jurkat cells increased nearly 60% when co-cultured with LNCaP (PSMA+), as compared with DU145 (PSMA-)., Conclusion: Here, we describe the ability of nanobody-based CAR to recognize PSMA that leads to the activation of Jurkat cells. This construct might be used as a promising candidate for clinical applications in prostate cancer therapy.

Prostate cancer is primarily fatal after it becomes metastatic and castration-resistant despite novel combined hormonal and chemotherapeutic regimens. Hence, new therapeutic concepts and drug delivery strategies are urgently needed for the eradication of this devastating disease. Here we report the highly specific, in situ click chemistry driven pretargeted delivery of cytotoxic drug carriers to PSMA(+) prostate cancer cells. Anti-PSMA 5D3 mAb and its F(ab') 2 fragments were functionalized with trans -cyclooctene (TCO), labeled with a fluorophore, and used as pretargeting components. Human serum albumin (ALB) was loaded with the DM1 antitubulin agent, functionalized with PEGylated tetrazine (PEG 4 -Tz), labeled with a fluorophore, and used as the drug delivery component. The internalization kinetics of components and the therapeutic efficacy of the pretargeted click therapy were studied in PSMA(+) PC3-PIP and PSMA(-) PC3-Flu control cells. The F(ab') 2 fragments were internalized faster than 5D3 mAb in PSMA(+) PC3-PIP cells. In the two-component pretargeted imaging study, both components were colocalized in a perinuclear location of the cytoplasm of PC3-PIP cells. Better colocalization was achieved when 5D3 mAb was used as the pretargeting component. Consecutively, the in vitro cell viability study shows a significantly higher therapeutic effect of click therapy in PC3-PIP cells when 5D3 mAb was used for pretargeting, compared to its F(ab') 2 derivative. 5D3 mAb has a longer lifetime on the cell surface, when compared to its F(ab') 2 analogue, enabling efficient cross-linking with the drug delivery component and increased efficacy. Pretargeting and drug delivery components were cross-linked via multiple bioorthogonal click chemistry reactions on the surface of PSMA(+) PC cells forming nanoclusters, which undergo fast cellular internalization and intracellular transport to perinuclear locations.

Background: Prostate cancer (PCa) is the second leading cause of cancer-related death in the Western population. The use in oncology of positron emission tomography/computed tomography (PET/CT) with emerging radiopharmaceuticals promises accurate staging of primary disease, restaging of recurrent disease and detection of metastatic lesions. Prostate-specific membrane antigen (PSMA) expression, directly related to androgen-independence, metastasis and progression, renders this tumour associate antigen a good target for the development of new radiopharmaceuticals for PET. Aim of this study was to demonstrate in a preclinical in vivo model (PSMA-positive versus PSMA-negative tumours) the targeting specificity and sensitivity of the anti-PSMA single-chain variable fragment (scFv) labelled with 124 I., Methods: The 124 I-labeling conditions of the antibody fragment scFvD2B were optimized and assessed for purity and immunoreactivity. The specificity of 124 I-scFvD2B was tested in mice bearing PSMA-positive and PSMA-negative tumours to assess both ex-vivo biodistribution and immune-PET., Results: The uptake fraction of 124 I-scFvD2B was very high on PSMA positive cells (range 75-91%) and highly specific and immuno-PET at the optimal time point, defined between 15 h and 24 h, provides a specific localization of lesions bearing the target antigen of interest (PSMA positive vs PSMA negative tumors %ID/g: p = 0.0198 and p = 0.0176 respectively) yielding a median target/background ratio around 30-40., Conclusions: Preclinical in vivo results of our immuno-PET reagent are highly promising. The target to background ratio is improved notably using PET compared to SPECT previously performed. These data suggest that, upon clinical confirmation of sensitivity and specificity, our anti-PSMA 124 I-scFvD2B may be superior to other diagnostic modalities for PCa. The possibility to combine in patients our 124 I-scFvD2B in multi-modal systems, such as PET/CT, PET/MR and PET/SPECT/CT, will provide quantitative 3D tomographic images improving the knowledge of cancer biology and treatment.

5D3 is a new high-affinity murine monoclonal antibody specific for prostate-specific membrane antigen (PSMA). PSMA is a target for the imaging and therapy of prostate cancer. 111 In-labeled antibodies have been used as surrogates for 177 Lu/ 90 Y-labeled therapeutics. We characterized 111 In-DOTA-5D3 by SPECT/CT imaging, tissue biodistribution studies, and dosimetry. Methods: Radiolabeling, stability, cell uptake, and internalization of 111 In-DOTA-5D3 were performed by established techniques. Biodistribution and SPECT imaging were done on male nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice bearing human PSMA(+) PC3 PIP and PSMA(-) PC3 flu prostate cancer xenografts on the upper right and left flanks, respectively, at 2, 24, 48, 72, and 192 h after injection. Biodistribution was also evaluated in tumor-free, healthy male CD-1 mice. Blocking studies were performed by coinjection of a 10-fold and 50-fold excess of 5D3 followed by biodistribution at 24 h to determine PSMA binding specificity. The absorbed radiation doses were calculated on the basis of murine biodistribution data, which were translated to a human adult man using organ weights as implemented in OLINDA/EXM. Results: 111 In-DOTA-5D3 was synthesized with specific activity of approximately 2.24 ± 0.74 MBq/μg (60.54 ± 20 μCi/μg). Distribution of 111 In-DOTA-5D3 in PSMA(+) PC3 PIP tumor peaked at 24 h after injection and remained high until 72 h. Uptake in normal tissues, including the blood, spleen, liver, heart, and lungs, was highest at 2 h after injection. Coinjection of 111 In-DOTA-5D3 with a 10- and 50-fold excess of nonradiolabeled antibody significantly reduced PSMA(+) PC3 PIP tumor and salivary gland uptake at 24 h but did not reduce uptake in kidneys and lacrimal glands. Significant clearance of 111 In-DOTA-5D3 from all organs occurred at 192 h. The highest radiation dose was received by the liver (0.5 mGy/MBq), followed by the spleen and kidneys. Absorbed radiation doses to the salivary and lacrimal glands and bone marrow were low. Conclusion: 111 In-DOTA-5D3 is a new radiolabeled antibody for imaging and a surrogate for therapy of malignant tissues expressing PSMA., (© 2019 by the Society of Nuclear Medicine and Molecular Imaging.)

Background and Aims : Prostate specific membrane antigen (PSMA) is specifically expressed on prostate epithelial cells and markedly overexpressed in almost all prostate cancers. TRIM24 is also up-regulated from localized prostate cancer to metastatic castration-resistant prostate cancer (CRPC). Because of the high relevance of TRIM24 for cancer development and the universal expression of PSMA in CPRC, we investigated the efficacy of human monoclonal PSMA antibody (PSMAb)-based platform for the targeted TRIM24 siRNA delivery and its therapeutic efficacy in CRPC in vivo and in vitro . Methods : The therapeutic complexes were constructed by conjugating PSMAb and sulfo-SMCC-protamine, and encapsulating TRIM24 siRNA. Flow cytometry, immunofluorescence, and fluorescence imaging were performed to detect the receptor-binding, internalization, and targeted delivery of PSMAb-sulfo-SMCC-protamine (PSP)-FAM-siRNA complex (PSPS) in vitro and in vivo . CCK-8, plate-colony formation, apoptosis, cell cycle, and Transwell assays were performed to evaluate the therapeutic potential of the PSP-TRIM24 siRNA complex in vitro , whereas the in vivo therapeutic efficacy was monitored by small animal imaging, radiography, and micro CT. Results : We confirmed that PSP could efficiently protect siRNA from enzymatic digestion, enable targeted delivery of siRNA, and internalize and release siRNA into PSMA-positive (PSMA+) prostate cancer cells in vitro and in vivo . Silencing TRIM24 expression by the PSP-TRIM24 siRNA complex could dramatically suppress proliferation, colony-formation, and invasion of PSMA+ CRPC cells in vitro , and inhibit tumor growth of PSMA+ CRPC xenografts and bone loss in PSMA+ CRPC bone metastasis model without obvious toxicity at therapeutic doses in vivo . Conclusion : PSMAb mediated TRIM24 siRNA delivery platform could significantly inhibit cell proliferation, colony-formation, and invasion in PSMA+ CRPC in vitro and suppressed tumor growth and bone loss in PSMA+ CRPC xenograft and bone metastasis model., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Adoptive cell transfer (ACT) is an emerging immunotherapy technique that restricts tumor growth and invasion in cancer patients. Among the different types of ACT, chimeric antigen receptor (CAR)T‑cell therapy is considered to be the most advanced and a potentially powerful technique for the treatment of cancer in clinical trials. The primary aim of CART‑cell therapy is to destroy cancer cells and therefore, it serves an important role in tumor immunotherapy. CART‑cell therapy has been demonstrated to mainly treat blood cancer by targeting cluster of differentiation (CD)‑19, CD20, CD22, CD33 and CD123. However, the use of CART‑cell therapy for treating solid tumors is currently under extensive investigation. With respect to prostate cancer, prostatic acid phosphatase, prostate‑specific antigen, prostate‑specific membrane antigen (PSMA), prostate stem cell antigen, T‑cell receptor γ alternate reading frame protein, transient receptor potential‑p8 and six‑transmembrane epithelial antigen of the prostate 1 are among the identified target antigens for prostate tumors. However, mesothelin, fibroblast activation protein, epidermal growth factor receptor, carcinoembryonic antigen, disialoganglioside‑2 and human epidermal growth factor 2 are among the main targets of CART‑cell therapy in the case of other types of solid tumors. The main challenges in CART‑cell therapy are the selection of the target antigens and the modulation of the ideal tumor microenvironment for T‑cells to fight against the cancer. The present review focuses on the 1st, 2nd, 3rd and 4th generations of anti‑PSMA CARs and their application for combating prostate carcinoma.

SPECT/CT images in patients have demonstrated the ability of [ 99m Tc]Tc-EDDA/HYNIC-Lys(Nal)-Urea-Glu ([ 99m Tc]Tc-iPSMA) to detect tumors and metastases of prostate cancer. Considering that theranostics combines the potential of therapeutic and diagnostic radionuclides in the same molecular probe, the aim of this research was to estimate the biokinetics and dosimetry of 177 Lu-DOTA-HYNIC-Lys(Nal)-Urea-Glu ( 177 Lu-iPSMA) in healthy subjects and analyze the response in patients receiving 177 Lu-iPSMA therapeutic doses. 177 Lu-iPSMA was obtained from lyophilized formulations with radiochemical purities >98%. Whole-body images from five healthy subjects were acquired at 20 min, 6, 24, 48, and 120 h after 177 Lu-iPSMA administration (185 MBq). The image sequence was used to extrapolate the 177 Lu-iPSMA time-activity curves of each organ to adjust the biokinetic model and calculate the total number of disintegrations ( N ) that occurred in the source regions. N data were the input for the OLINDA/EXM code to calculate internal radiation doses. Ten patients (median age: 68 y; range 58-86 y) received from 1 to 4 cycles of 177 Lu-iPSMA (3.7 or 7.4 GBq) every 8-10 weeks. Response was evaluated using the 68 Ga-PSMA-ligand-PET/CT or 99m Tc-iPSMA-SPECT/CT diagnostic images and serum PSA levels before and after 177 Lu-iPSMA treatment. The blood activity showed a half-life value of 1.1 h for the fast component ( T 1/2 α = ln2/0.614), 9.2 h for the first slow component ( T 1/2 β = ln2/0.075), and 79.6 h for the second slow component ( T 1/2 γ = ln2/0.008). The average absorbed doses were 0.23, 0.28, 0.88, and 1.17 Gy/GBq for the spleen, liver, kidney, and salivary glands. A total of 18 cycles were performed in 10 patients. A PSA decrease and some reduction of the radiotracer uptake (SUV) in tumor lesions occurred in 60% and 70% of the patients, respectively. 177 Lu-iPSMA obtained from kit formulations showed high tumor uptake with good response rates in patients. The results obtained in this study warrant further clinical studies to establish the optimal number of treatment cycles and for evaluating the effect of this therapeutic agent on survival of patients.

The main purpose of this study was to develop a prostate-specific membrane antigen (PSMA) antibody-conjugated drug-loaded nanomicelles using MPEG--PLA-PCL-PLA-PEG-NH2 pentablock copolymer for targeted delivery of hydrophobic anticancer drugs to prostate cancer cells. During this experiment, monomers of L-lactide, ε-caprolactone, poly(ethylene glycol)-methyl ether, and poly(ethylene glycol)-NH2 were used to prepare pentablock copolymer using the ring opening technique. The pentablock nanomicellar (PBNM) formulation was prepared by the evaporation-rehydration method. The resultant pentablock nanomicelles were then conjugated with PSMA antibody resulting in PSMA-Ab-PTX-PBNM. Both the block copolymers and the nanomicelles were analyzed by hydrogen nuclear magnetic resonance (H-NMR), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The obtained nanomicelles (NM) were then analyzed for size and zeta potential using dynamic light scattering-dynamic laser scattering (DLS) and then further submitted to H-NMR and TEM analyses. The XRD, FTIR, and the H-NMR analyses confirmed the structure of the pentablock copolymers. The average size for conjugated nanomicellar was 45 nm ± 2.5 nm. The average (ζ-potential) was around - 28 mV. H-NMR and FTIR analysis done on PSMA-coupled paclitaxel-loaded PBNM showed peaks characteristic of the drug (paclitaxel) and the polymer, confirming the successful encapsulation. TEM analysis showed well-defined spherical morphology and confirmed the size range obtained by the DLS. In vitro release studies revealed sustained slow of PTX in phosphate buffer solution (PBS). Confocal scanning microscopy (TEM) of coumarin6-loaded in PBNM indicated that pentablock nanomicelles were internalized into the prostate cancer (PC-3) cells. Cell proliferation assay showed that nanomicelles ferried paclitaxel into the PC-3 cells and subsequently reduced the cell proliferation. The results depict PTX-PBNM-Ab as a suitable carrier for targeted delivery of drugs to prostate cancer cells.

Prostate cancer (PCa) is a leading cause of cancer-related death among males globally. To date, prostate-specific antigen (PSA), as a typical tumour marker, has been widely used in the early diagnosis of PCa. However, in practical clinical tests, high serum levels of PSA show a high probability for false-positive results, leading to misdiagnoses. In this study, we developed a new classification system for PCa, benign prostate hyperplasia (BPH) and healthy subjects by using a surface-enhanced Raman scattering (SERS)-based immunoassay of multiple tumour markers along with a support vector machine (SVM) algorithm. Silver nanoparticles (AgNPs) as immune probes and SiC@Ag@Ag-NPs SERS as immune substrates were constructed into a sandwich structure to serve as an ultrasensitive SERS-based immunoassay platform of tumour markers. With this assay, the limits of detection for PSA, prostate-specific membrane antigen (PSMA) and human kallikrein 2 (hK2) were as low as 0.46 fg mL -1 , 1.05 fg mL -1 and 0.67 fg mL -1 , respectively. Furthermore, the serum levels of PSA, PSMA and hK2 in clinical samples were successfully detected using the SERS-based immunoassay platform, and correct classifications of PCa, BPH and healthy subjects were feasible with help of the linear SVM algorithm. These results demonstrate the potential for improving the diagnostic accuracy of PCa. Overall, the linear SVM classification model with multiple tumour markers exhibited good classifications of PCa, BPH and healthy subjects, with a PCa diagnostic accuracy of 70% that was significantly superior to that of the linear SVM classification model based only on the serum level of PSA (50%). Therefore, combining the SERS-based immunoassay with pattern recognition technology can allow for comprehensive analyses of the serum levels of multiple tumour markers to effectively improve the diagnostic accuracy of cancer with potential applications in point-of-care testing., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Small therapeutic proteins represent a promising novel approach to treat cancer. Nevertheless, their clinical application is often adversely impacted by their short plasma half-life. Controlled long-term delivery of small biologicals has become a challenge because of their hydrophilic properties and in some cases their limited stability. Here, an in situ forming depot-injectable polymeric system was used to deliver BiJ591, a bispecific T-cell engager (BiTE) targeting both prostate-specific membrane antigen (PSMA) and the CD3 T-cell receptor in prostate cancer. BiJ591 induced T-cell activation, prostate cancer-directed cell lysis, and tumor growth inhibition. The use of diblock (DB) and triblock (TB) biodegradable polyethylene glycol-poly(lactic acid; PEG-PLA) copolymers solubilized in tripropionin, a small-chain triglyceride, allowed maintenance of BiJ591 stability and functionality in the formed depot and controlled its release. In mice, after a single subcutaneous injection, one of the polymeric candidates, TB1/DB4, provided the most sustained release of BiJ591 for up to 21 days. Moreover, the use of BiJ591-TB1/DB4 formulation in prostate cancer xenograft models showed significant therapeutic activity in both low and high PSMA-expressing tumors, whereas daily intravenous administration of BiJ591 was less efficient. Collectively, these data provide new insights into the development of controlled delivery of small therapeutic proteins in cancer. Mol Cancer Ther; 17(9); 1927-40. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Background: Prostate-specific membrane antigen (PSMA)-based radiopeptide/radioligand therapy represents a rapidly expanding field in the management of metastatic castrate-resistant prostate cancer (mCRPC). However, there remains concern for the development of significant toxicities in heavily pretreated patients. In this study, the authors present their local experience, with respect to efficacy and toxicity, of 22 consecutive patients treated with lutetium-177-DOTAGA-(I-y)fk(Sub-KuE) or 177 Lu-PSMA I&T radioimmunotherapy for progressive mCRPC, followed up over 1 year., Materials and Methods: All patients had progressive mCRPC, an European Cooperative Oncology Group (ECOG) ≤2 with adequate bone marrow and liver function. 177 Lu-PSMA I&T therapy was administered at 8-week intervals with a mean prescribed activity of 5.5 GBq (gigabecquerel) per patient., Results: Twenty patients had evaluable results, median age of 71 years, and median duration of follow-up of 17 months. Three patients (15%) experienced a G1/2 myelotoxicity and four (20%) G3/4. No incidences of myelodysplasia/acute leukemia have been identified. All toxicities were self-limiting. Baseline cytopenia was predictive of the development of subsequent G3/4 myelotoxicity (p = 0.0035). Eight patients (40%) experienced an objective PSA response, with a median time to response of 15 weeks. The median time to PSA progression was not reached. Patients receiving three cycles of therapy were statistically more likely to experience a disease response when compared to those treated with one, two, or four cycles (p < 0.0001)., Conclusions: 177 Lu-PSMA I&T radioimmunotherapy of progressive mCRPC is safe and effective with three cycles being the potential optimal number for determining long-term disease response.

Herein, we describe the in vivo effects of doxorubicin (DOX) encapsulated in ubiquitous protein apoferritin (APO) and its efficiency and safety in anti-tumor treatment. APODOX is both passively (through Enhanced Permeability and Retention effect) and actively targeted to tumors through prostate-specific membrane antigen (PSMA) via mouse antibodies conjugated to the surface of horse spleen APO. To achieve site-directed conjugation of the antibodies, a HWRGWVC heptapeptide linker was used. The prostate cancer-targeted and non-targeted nanocarriers were tested using subcutaneously implanted LNCaP cells in athymic mice models, and compared to free DOX. Prostate cancer-targeted APODOX retained the high potency of DOX in attenuation of tumors (with 55% decrease in tumor volume after 3 weeks of treatment). DOX and non-targeted APODOX treatment caused damage to liver, kidney and heart tissues. In contrast, no elevation in liver or kidney enzymes and negligible changes were revealed by histological assessment in prostate cancer-targeted APODOX-treated mice. Overall, we show that the APO nanocarrier provides an easy encapsulation protocol, reliable targeting, high therapeutic efficiency and very low off-target toxicity, and is thus a promising delivery system for translation into clinical use.

Current immunotherapy has limited efficacy on metastatic castrate-resistant prostate cancer (mCRPC). We therefore sought to improve the antitumor ability of mCRPC patient-derived CD8 + T-cells by the endowment of specificity to prostate-specific membrane antigen (PSMA) and insensitivity to immunosuppressant molecule transforming growth factor-β (TGF-ß) under the control of herpes simplex virus-1 thymidine kinase. CD8 + T-cells were collected by leukapheresis and cultured in a Food and Drug Administration-approved Cell Processing Work Station. We developed a chimeric antigen receptor retroviral construct using an anti-PSMA chimeric immunoglobulin-T-cell receptor(ζ) gene (PZ1) and dominant negative TGF-ß type II receptor (TßRIIDN), that could induce CD8 + T-cells to be PSMA reactive and insensitive to TGF-ß. Cr 51 release assay was performed on PC-3 and PC-3-PSMA. The further antitumor functions of PSMA-specific, TGF-ß insensitive CD8 + T-cells was evaluated using an immunodeficient RAG-1 -/- mouse model. We found PSMA-specific, TGF-ß insensitive CD8 + T-cells from mCRPC were expanded with strong expression of PZ1 and thymidine kinase genes, and their growth was not suppressed by TGF-ß. The survival of these cells decreased sharply after treatment with ganciclovir. Treatment of PSMA-specific TGF-ß, insensitive CD8 + T-cells was associated with 61.58% specific lysis on PC-3-PSMA, and significantly suppressed PC3-PSMA tumor compared with the PC3 tumor. A large amount of tumor apoptosis and CD8 + T-cell infiltration were found only in the PC3-PSMA tumor. This study verified that PSMA-specific, TGF-ß insensitive CD8 + T-cells derived from mCRPC patients could be successfully expanded and used to overcome the immunosuppressive effects of the tumor microenvironment to control PSMA-expressing PC in vitro and in vivo. This may provide a promising approach for men with mCRPC who fail androgen deprivation therapy., Patient Summary: We investigated the role of a novel chimeric antigen receptor T-immunotherapy based on autologous metastatic castrate-resistant prostate cancer patient-derived prostate-specific membrane antigen (PSMA)-specific, transforming growth factor-ß insensitive CD8 + T-cells on PSMA-positive prostate cancer. We found that this chimeric antigen receptor T-cells could kill PSMA-positive prostate cancer specifically. The results suggest that this novel immunotherapy treatment is a potential new approach for men with metastatic castrate-resistant prostate cancer., (Copyright © 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Molecular imaging and therapy is a rapidly evolving field in research and clinical medicine. The use of the exciting and attractive properties of radioisotopes for imaging and therapy has made Nuclear Medicine very significant when it comes to molecular imaging/therapy. Monoclonal Antibodies (mAbs) on the other hand are very important targeting biomolecules with high affinity that can "carry" the radioisotope of choice. Herein we make a brief overview of the radiolabeled mAbs that target prostate specific membrane antigen (PSMA) and their use in the management of patients with prostate cancer (PCa).

Background: We generated humanized/de-immunized immunotoxins targeting the prostate-specific membrane antigen (PSMA) and tested their cytotoxic activity against prostate cancer cells in vitro., Materials and Methods: The humanized/de-immunized version of our murine anti-PSMA single-chain antibody fragment (scFv) D7, termed hD7-1(VL-VH), was ligated to the 40-kDa toxin domain of Pseudomonas aeruginosa exotoxin A (PE40), and to the deimmunized 24-kDa toxin domains PE24 or PE24mut. The immunotoxins designated as hD7-1(VL-VH)-PE40, hD7-1(VL-VH)-PE24 and hD7-1(VL-VH)-PE24mut were bacterially expressed and purified by affinity chromatography. Binding and cytotoxicity were examined by flow cytometry and viability assay, respectively., Results: All immunotoxins revealed strong binding to prostate cancer cells expressing PSMA and specific cytotoxicity, with half-maximal inhibitory concentration values in the picomolar range., Conclusion: We successfully created powerful anti-PSMA immunotoxins with reduced immunogenicity for further clinical development and application against advanced prostate cancer., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Bioconjugate formats provide alternative strategies for antigen targeting with bispecific antibodies. Here, PSMA-targeted Fab conjugates were generated using different bispecific formats. Interchain disulfide bridging of an αCD3 Fab enabled installation of either the PSMA-targeting small molecule DUPA (SynFab) or the attachment of an αPSMA Fab (BisFab) by covalent linkage. Optimization of the reducing conditions was critical for selective interchain disulfide reduction and good bioconjugate yield. Activity of αPSMA/CD3 Fab conjugates was tested by in vitro cytotoxicity assays using prostate cancer cell lines. Both bispecific formats demonstrated excellent potency and antigen selectivity., (Copyright © 2017. Published by Elsevier Ltd.)

Background: Diagnosis of metastatic prostate adenocarcinoma (metPA) in cytology specimens can be challenging and frequently requires the use of immunohistochemistry (IHC). Prostate specific membrane antigen (PSMA) and NKX3.1 have emerged as promising IHC markers to determine prostatic origin of metPA in surgical specimens. Our goal is to evaluate the performance of PSMA and NKX3.1 and compare them with those of prostate-specific antigen (PSA) and prostate specific alkaline phosphatase (PSAP) in the cytological diagnosis of metPA MATERIALS: Cytology specimens from patients with a history of prostate adenocarcinoma at our institution between January 01, 2005 and December 31, 2015 were retrieved. IHC stains were performed on the cell blocks. In addition to the staining pattern and intensity, the sensitivity, and specificity of PSMA and NKX3.1 were assessed and compared to those of PSA and PSAP markers., Results: A total of 56 cytology cases were retrieved with the following diagnoses: 13 metPA, 37 metastatic carcinomas from other origins, 4 rare atypical cells, and 2 benign. Additional 9 cases were re-classified as metPA based on positive PSMA and/or NKX3.1 immunostains. In our cohort of 22 cases of metPA, 18 were positive for PSMA (82%), 15 for NKX3.1 (68%), 9 for PSA (41%), and 9 for PSAP (41%). PSMA and NKX3.1 were negative in all 6 cases of metastatic carcinoma of nonprostate origin (specificity 100%). PSMA demonstrated strong membranous staining pattern, and NKX3.1 exhibited moderate nuclear staining pattern., Conclusion: Because of their higher sensitivity and specificity, PSMA and NKX3.1 are valuable surrogate markers for metPA in cytology specimens, when compared with PSA and PSAP markers., (© 2017 Wiley Periodicals, Inc.)

Objectives: PSMA (prostate-specific membrane antigen) is overexpressed in prostate cancer cells and is reported to be a promising target for antibody-based radioligand therapy in patients with metastasized prostate cancer. Since PSMA expression is not restricted to prostate cancer, the underlying study investigates PSMA expression in non-small cell lung cancer (NSCLC)., Material and Methods: Immunohistochemistry was used to identify PSMA expression in n = 275 samples of NSCLC tissue specimens. By means of CD34 co-expression, the level of PSMA expression in tumor associated neovasculature was investigated. The impact of PSMA expression on clinicopathologic parameters and prognosis was evaluated., Results: PSMA tumor cell expression in NSCLC is as low as 6% and was predominantly found in squamous cell carcinoma (p = 0.002). Neovascular PSMA expression was found in 49% of NSCLC. High neovascular PSMA expression was associated with higher tumor grading (G3/G4) (p < 0.001). Neither for PSMA tumor cell expression, nor for PSMA neovascular cell expression prognostic effects were found for the investigated NSCLC cases., Conclusion: Here, we report on the expression of PSMA in NSCLC tissue samples. Against the background of a potential treatment with radiolabeled PSMA ligands, our data might serve for the future identification of patients who could benefit from this therapeutic option.

We present the case of a 79-year-old man with an elevated postprostatectomy prostate-specific antigen level who was sequentially imaged with positron emission tomography/computed tomography (PET/CT) using 18 F-fluciclovine followed by PSMA-targeted 18 F-DCFPyL. Although both imaging tests successfully identified the same pelvic recurrence, each radiotracer had its relative merits. This case highlights the differences between these two PET radiotracers, which are increasingly being used to image men with recurrent prostate cancer., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Evidence from preclinical and animal studies demonstrated an anticancer effect of flaxseed lignans, particularly enterolactone (ENL), against prostate cancer. However, extensive first-pass metabolism following oral lignan consumption results in their systemic availability primarily as glucuronic acid conjugates (ENL-Gluc) and their modest in vivo effects. To overcome the unfavorable pharmacokinetics and improve their effectiveness in prostate cancer, antibody-directed enzyme prodrug therapy (ADEPT) might offer a novel strategy to allow for restricted activation of ENL from circulating ENL-Gluc within the tumor environment. The anti-prostate-specific membrane antigen (PSMA) antibody D7 was fused with human β-glucuronidase (hβG) via a flexible linker. The binding property of the fusion construct, D7-hβG, against purified or cell surface PSMA was determined by flow cytometry and Octet Red 384 system, respectively, with a binding rate constant, K d, of 2.5 nM. The enzymatic activity of D7-hβG was first tested using the probe, 4-methylumbelliferone glucuronide. A 3.8-fold greater fluorescence intensity was observed at pH 4.5 at 2 h compared with pH 7.4. The ability of D7-hβG to activate ENL from ENL-Gluc was tested and detected using LC-MS/MS. Enhanced generation of ENL was observed with increasing ENL-Gluc concentrations and reached 3613.2 ng/mL following incubation with 100 μM ENL-Gluc at pH 4.5 for 0.5 h. D7-hβG also decreased docetaxel IC 50 value from 23 nM to 14.9 nM in C4-2 cells. These results confirmed the binding and activity of D7-hβG and additional in vitro investigation is needed to support the future possibility of introducing this ADEPT system to animal models.

Introduction: Prostate-specific membrane antigen (PSMA) is an extensively studied antigen for imaging prostate cancer. We prepared a single-chain variable fragment (scFv) of J591, a monoclonal antibody that recognises an external epitope of PSMA, incorporating a His-tag for labelling with Tc tricarbonyl, and evaluated its binding using human PCa cell lines., Methods: J591(scFv) was expressed in HEK-293T cells and purified by metal ion affinity chromatography, followed by size exclusion chromatography. Stability and monomer/dimer ratios of purified scFv under different storage conditions were analysed by SDS-PAGE and analytical size exclusion chromatography. J591(scFv) was labelled with (Equation is included in full-text article.)at 37°C for 60 min. The stability of Tc-scFv in human serum was analysed by SDS-PAGE with autoradiography. Cell-binding studies were carried out using PC3LN3 (PSMA negative) and PC3LN3-PSMA (a variant engineered to express PSMA) cell lines., Results: J591(scFv) was most stable to dimerisation on storage at -80°C compared with -20 and 4°C. Radiochemical yields of 85-90% were obtained with the final radiochemical purity of more than 99% after purification by gel filtration. In these small-scale studies, the maximum specific activity achieved was 7 MBq/μg. Liquid chromatography-mass spectrometry showed the formation of Tc-J591(scFv), which was radiochemically stable in serum, with no dissociation of Tc over 24 h. Cell-binding assays showed specific binding to PSMA-positive cells., Conclusion: J591(scFv) can be radiolabelled with (Equation is included in full-text article.)conveniently and efficiently. The labelled product was stable in serum. It showed selective binding to PSMA-positive cells compared with PSMA-negative cells. This potential radiotracer warrants evaluation in PCa xenograft models.

Prostate specific membrane antigen (PSMA) targeted microbubbles (MBs) were developed using bioorthogonal chemistry. Streptavidin-labeled MBs were treated with a biotinylated tetrazine (MBTz) and targeted to PSMA expressing cells using trans-cyclooctene (TCO)-functionalized anti-PSMA antibodies (TCO-anti-PSMA). The extent of MB binding to PSMA positive cells for two different targeting strategies was determined using an in vitro flow chamber. The initial approach involved pretargeting, where TCO-anti-PSMA was first incubated with PSMA expressing cells and followed by MBTz, which subsequently showed a 2.8 fold increase in the number of bound MBs compared to experiments performed in the absence of TCO-anti-PSMA. Using direct targeting, where TCO-anti-PSMA was linked to MBTz prior to initiation of the assay, a 5-fold increase in binding compared to controls was observed. The direct targeting approach was subsequently evaluated in vivo using a human xenograft tumor model and two different PSMA-targeting antibodies. The US signal enhancements observed were 1.6- and 5.9-fold greater than that for non-targeted MBs. The lead construct was also evaluated in a head-to-head study using mice bearing both PSMA positive or negative tumors in separate limbs. The human PSMA expressing tumors exhibited a 2-fold higher US signal compared to those tumors deficient in human PSMA. The results demonstrate both the feasibility of preparing PSMA-targeted MBs and the benefits of using bioorthogonal chemistry to create targeted US probes.

Background: Prostate-specific membrane antigen (PSMA) is a validated target for the imaging and therapy of prostate cancer. Here, we report the detailed characterization of four novel murine monoclonal antibodies (mAbs) recognizing human PSMA as well as PSMA orthologs from different species., Methods: Performance of purified mAbs was assayed using a comprehensive panel of in vitro experimental setups including Western blotting, immunofluorescence, immunohistochemistry, ELISA, flow cytometry, and surface-plasmon resonance. Furthermore, a mouse xenograft model of prostate cancer was used to compare the suitability of the mAbs for in vivo applications., Results: All mAbs demonstrate high specificity for PSMA as documented by the lack of cross-reactivity to unrelated human proteins. The 3F11 and 1A11 mAbs bind linear epitopes spanning residues 226-243 and 271-288 of human PSMA, respectively. 3F11 is also suitable for the detection of PSMA orthologs from mouse, pig, dog, and rat in experimental setups where the denatured form of PSMA is used. 5D3 and 5B1 mAbs recognize distinct surface-exposed conformational epitopes and are useful for targeting PSMA in its native conformation. Most importantly, using a mouse xenograft model of prostate cancer we show that both the intact 5D3 and its Fab fragment are suitable for in vivo imaging., Conclusions: With apparent affinities of 0.14 and 1.2 nM as determined by ELISA and flow cytometry, respectively, 5D3 has approximately 10-fold higher affinity for PSMA than the clinically validated mAb J591 and, therefore, is a prime candidate for the development of next-generation theranostics to target PSMA. Prostate 77:749-764, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

How to overcome the low accumulation of chemotherapeutic agent in tumor tissue and exhibit multitherapeutics remains an ongoing challenge for cancer treatment. Here, a simple method is demonstrated that used to prepare prostate-specific membrane antigen antibody (PSMA ab )-conjugated fluorescent bovine serum albumin (BSA)-branched polyethylenimine layer-by-layer nanoparticles (BSA-PEI LBL NPs) for co-delivery of docetaxel (DTX) and p44/42 mitogen-activated protein kinase (MAPK) small interfering RNA (p44/42 MAPK siRNA) as synergistic and selective inhibition of cancer cell proliferation platform. The results show the levels of α-tubulin and p44/42 MAPK in CWR22R cells are significantly reduced after treatment with PSMA ab -conjugated DTX/BSA-PEI LBL /siRNA NPs. Consequently, the 50% cellular growth inhibition (IC 50 ) values of the NPs loaded with both DTX and p44/42 MAPK siRNA are ≈2.1-fold less than those for the NPs only loaded with DTX. The median survival significantly prolongs from 18 d to upward 45 d compared to mice that receive same dose (12 mg kg -1 ) of free DTX. The results suggest this synergistic delivery system may be a promising clinical treatment in prostate cancer., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Introduction: Single chain (scFv) antibodies are ideal targeting ligands due to their modular structure, high antigen specificity and affinity. These monovalent ligands display rapid tumor targeting but have limitations due to their fast urinary clearance., Methods: An anti-prostate membrane antigen (PSMA) scFv with a site-specific cysteine was expressed and evaluated in a prostate cancer xenograft model by Cu-64 PET imaging. To enhance tumor accumulation, the scFv-cys was conjugated to the co-polymer DSPE-PEG-maleimide that spontaneously assembled into a homogeneous multivalent lipid nanoparticle (LNP)., Results: The targeted LNP exhibited a 2-fold increase in tumor uptake compared to the scFv alone using two different thiol ester chemistries. The anti-PSMA scFv-LNP exhibited a 1.6 fold increase in tumor targeting over the untargeted LNP., Conclusions: The targeted anti-PSMA scFv-LNP showed enhanced tumor accumulation over the scFv alone or the untargeted DOTA-micelle providing evidence for the development of this system for drug delivery., Advances in Knowledge and Implications for Patient Care: Anti-tumor scFv antibody fragments have not achieved their therapeutic potential due to their fast blood clearance. Conjugation to an LNP enables multivalency to the tumor antigen as well as increased molecular size for chemotherapy drug delivery., (Copyright © 2017 Elsevier Inc. All rights reserved.)