Nanoparticle-Based Strategies to Enhance PSMA-Targeted Radioligand Therapy: A Review of the Delivery, Co-Formulation, and Combination Landscape Surrounding Lutetium Lu 177 Vipivotide Tetraxetan (Pluvicto)

1. Introduction

Prostate cancer remains one of the most common malignancies affecting men worldwide, and metastatic castration-resistant prostate cancer (mCRPC) continues to represent a major cause of cancer-related mortality despite advances in androgen receptor pathway inhibitors (ARPIs), taxane chemotherapy, and immunotherapy. Prostate-specific membrane antigen (PSMA), a type II transmembrane glycoprotein markedly overexpressed on the surface of prostate cancer cells and further upregulated with castration resistance and metastatic progression, has become the dominant molecular target for both diagnostic imaging and targeted radioligand therapy (RLT) in this disease.

Lutetium Lu 177 vipivotide tetraxetan, marketed as Pluvicto, is a small-molecule PSMA-617 ligand conjugated to the beta-emitting radionuclide lutetium-177 via a DOTA-based chelator, initially approved by the FDA in March 2022 for PSMA-positive mCRPC following the pivotal VISION trial [1] and subsequently extended through the TheraP and PSMAfore trials [2,3] and, most recently, through the PSMAddition trial and a July 2026 label expansion, to androgen pathway modulation-naive and -sensitive metastatic disease in combination with ARPI therapy [5,6] This trajectory reflects a broader shift toward earlier, more integrated use of radioligand therapy across the prostate cancer treatment continuum

Nonetheless, 177Lu-PSMA-617 is a small molecule (approximately 1 kDa) with rapid renal clearance and biodistribution governed largely by PSMA expression together with non-specific uptake in the salivary and lacrimal glands and the proximal renal tubules [13,14] These pharmacokinetic properties translate clinically into xerostomia, nephrotoxicity risk, and myelosuppression, and constrain the absorbed radiation dose that can be delivered to tumor tissue before normal-organ dose limits are reached [8] In parallel, patients with low, heterogeneous, or PSMA-negative disease derive limited benefit from ligand-based targeting alone [11]

Nanotechnology offers a set of design principles that address these limitations: prolonged circulation half-life through increased hydrodynamic size, tumor accumulation through active PSMA-mediated targeting and passive EPR-mediated deposition, multivalent ligand presentation, and the capacity to co-encapsulate multiple imaging or therapeutic payloads within a single carrier. Over the past decade, a substantial preclinical literature has applied these principles to PSMA-directed platforms, though, as this review shows, direct integration of nanoparticles with the FDA-approved 177Lu-PSMA-617 construct itself is only beginning to be demonstrated, with the most mature radionuclide-nanoparticle work instead built around related PSMA ligands, alternative radioisotopes, and combination imaging/therapy modalities.

This review has three aims: first, to summarize the mechanism, clinical evidence base, and recognized toxicity and efficacy limitations of Pluvicto that motivate nanoparticle-based interventions; second, to catalog the major nanoparticle platforms engineered for PSMA-targeted radionuclide delivery or positioned as adjuncts to radioligand therapy; and third, to critically evaluate the translational distance between this preclinical work and clinical application, identifying research priorities most likely to yield a nanoparticle-enhanced successor to, or combination partner for, Pluvicto.

2. Pluvicto: Mechanism, Clinical Evidence, and Recognized Limitations

2.1. Mechanism of Action

Vipivotide tetraxetan is a urea-based small molecule built around a glutamate-urea-lysine pharmacophore that binds the extracellular substrate pocket of PSMA with high affinity and selectivity. The ligand is conjugated through a linker to DOTA, which chelates the beta- and gamma-emitting radionuclide lutetium-177. Following intravenous administration, the agent binds PSMA on the tumor cell surface, is internalized via receptor-mediated endocytosis, and delivers cytotoxic beta-particle radiation with concomitant low-abundance gamma emission, thereby enabling post-therapy imaging and dosimetry.

2.2. Clinical Development Timeline

The VISION trial established the initial efficacy signal: in taxane- and ARPI-pretreated mCRPC, 177Lu-PSMA-617 plus standard of care improved median overall survival to 15.3 months versus 11.3 months for standard of care alone, and improved radiographic progression-free survival (rPFS) to 8.7 versus 3.4 months, leading to FDA approval in March 2022[1] The TheraP phase II trial subsequently demonstrated a higher PSA response rate with 177Lu-PSMA-617 (66%) compared with cabazitaxel (37%) in a similar post-docetaxel population [2]

The PSMAfore trial extended the evidence base to taxane-naive mCRPC patients who had progressed on one ARPI, showing an rPFS benefit (9.3 versus 5.6 months) compared with a second ARPI switch, supporting a 2024 label expansion [3]. A final overall-survival and safety analysis of this trial was subsequently reported [4]

Most recently, the phase III PSMAddition trial tested 177Lu-PSMA-617 combined with ARPI therapy against ARPI alone in androgen pathway modulation-naive or -sensitive metastatic disease; the trial met its primary rPFS endpoint (hazard ratio 0.72, 95% CI 0.58-0.90), leading to a further FDA label expansion in July 2026 that moves radioligand therapy earlier in the prostate cancer treatment sequence [5,6]

2.3. Recognized Toxicity and Pharmacokinetic Limitations

Across this trial program, the recurring toxicity signals are xerostomia, myelosuppression (grade 3 or higher anemia, thrombocytopenia, and leukopenia), fatigue, and nausea, alongside warnings for radiation exposure, renal toxicity, and infertility [6,13] and a recent narrative review reports grade-3-or-higher anemia in roughly 12.9% of patients, thrombocytopenia in 7.9%, and mild-to-moderate xerostomia in approximately 38.8%[8]

These toxicities arise directly from the pharmacokinetic profile of a small, rapidly filtered molecule; strategies to reduce salivary and renal uptake of small-molecule PSMA radiopharmaceuticals have been proposed at the ligand-design level [14], while comprehensive dosimetry meta-analyses of 177Lu-PSMA therapies confirm consistent, quantifiable renal and salivary gland absorbed-dose burdens across cohorts [16]

A second, distinct limitation is heterogeneity of PSMA expression: patients with low tumor PSMA avidity or PSMA-discordant lesions derive substantially less benefit from ligand-based targeting, since therapeutic efficacy is mechanistically coupled to receptor density [11]

Efforts to modify the pharmacokinetics of PSMA ligands using an albumin-binding moiety illustrate both the promise and the difficulty of this approach without full nanoparticle encapsulation: the albumin-binding ligand 177Lu-PSMA-ALB-56 achieved substantially higher tumor absorbed dose (approximately 1.4- to 2.3-fold higher than PSMA-617) by extending blood half-life, but this came at the cost of a roughly 3.3-fold increase in absorbed renal dose [15] underscoring that simply prolonging circulation time, without a targeting and clearance strategy specifically engineered to spare normal tissue, can shift rather than solve the therapeutic-index problem. This trade-off is a central design constraint for any nanoparticle-based reformulation of PSMA-targeted radioligand therapy.

3. Rationale for Nanoparticle Integration with PSMA-Targeted Radioligand Therapy

Nanoparticle carriers, generally defined as engineered structures in the 1-200 nm range, offer several mechanisms that map directly onto the limitations described above.

Prolonged circulation and tumor dwell time. Nanoparticles above the renal filtration cutoff (~8 nm hydrodynamic diameter) avoid rapid glomerular clearance, extending blood half-life relative to free PSMA-617, which increases the cumulative probability of tumor engagement [18]

Dual targeting via active and passive mechanisms. Surface conjugation of PSMA-binding ligands confers active targeting, while the EPR effect in tumor vasculature contributes passive accumulation, though EPR-driven background uptake can also erode target selectivity at high ligand valency [18]

Multivalency and avidity. Dendrimer and liposome scaffolds can present multiple copies of a PSMA ligand on a single particle, increasing functional binding avidity relative to a monovalent small molecule, particularly relevant for tumors with lower PSMA receptor density [18,20]

Multimodal and combinatorial payloads. A single nanoparticle can co-encapsulate a radionuclide chelator, a therapeutic or gene-silencing payload, and an imaging reporter, enabling simultaneous diagnosis, therapy, and treatment monitoring -- the defining feature of nanotheranostics [18,25]

Radioprotection of normal tissue. Because nanoparticle biodistribution is governed less by receptor pharmacology alone and more by particle size, surface charge, and reticuloendothelial clearance, appropriately engineered carriers may, in principle, reduce off-target salivary and renal uptake relative to free small-molecule ligands, and separately, pharmacologic radioprotective strategies are being explored to blunt salivary gland toxicity during conventional 177Lu- and 225Ac-PSMA therapy [13,17]

These mechanisms are not mutually exclusive, and much of the literature reviewed below combines two or more of them within a single nanoplatform. It is important to state at the outset, however, that most published work uses PSMA-targeted nanoparticles as imaging agents, drug-delivery vehicles, or platforms for alternative radionuclides rather than as direct reformulations of 177Lu-PSMA-617/Pluvicto itself [18,26] This distinction matters for interpreting the clinical relevance of the evidence base and is discussed further in Section 8.

4. Nanoparticle Platforms Investigated for PSMA-Targeted Radionuclide Delivery

4.1. Gold Nanoparticles

Gold nanoparticles (AuNPs) are among the most extensively characterized inorganic nanocarriers for radiolabeling because of their well-established synthesis chemistry, tunable size, and biocompatibility [19] Apostolopoulou and colleagues synthesized ~20 nm AuNPs via a modified Turkevich method, functionalized them with a thiolated PSMA-targeting peptide produced by solid-phase peptide synthesis, and conjugated the TADOTAGA chelator to enable 177Lu radiolabeling, achieving radiolabeling yields of 98.55 ± 0.63%[19] The resulting [177Lu]Lu-AuNP-TADOTAGA construct was stable in PBS, human serum, and DTPA challenge over 15 days and produced a marked, PSMA-selective reduction in viability of PSMA-expressing LNCaP cells relative to PSMA-negative PC3 controls, with in vivo biodistribution studies planned as a next step [19] This work represents one of the most direct examples in the current literature of engineering a nanoparticle specifically to carry the 177Lu radionuclide used in Pluvicto to a PSMA-expressing target.

4.2. PAMAM Dendrimers

Dendrimers -- highly branched, monodisperse polymers with a defined number of surface functional groups -- allow precise control over ligand valency. Lesniak and colleagues evaluated a generation-4 polyamidoamine (PAMAM) dendrimer conjugated to the PSMA ligand ACUPA and found markedly extended blood half-life relative to a non-targeted control dendrimer, along with PSMA-selective tumor accumulation in PC3-Pip (PSMA-positive) versus PC3-Flu (PSMA-negative) xenografts [20] The same group subsequently extended this platform to multimodal PAMAM dendrimer-drug conjugates for prostate cancer treatment [21] and a related PSMA-targeted, 2-deoxyglucose-based dendrimer nanomedicine has since been reported by an independent group, combining PSMA-targeted delivery with a glycolysis-disrupting payload [22]

A review of the broader dendrimer literature notes that triazine dendrimer constructs bearing between 4 and 64 copies of a PSMA urea ligand (generations G1 through G5) provide an instructive lesson in nanoparticle design: the smallest construct achieved high, PSMA-selective tumor uptake, whereas the largest accumulated similarly in PSMA-positive and PSMA-negative tumors, indicating that an EPR-dominated, non-selective uptake mechanism had overtaken active PSMA targeting at high molecular weight and valency [18] This finding is directly relevant to any effort to scale up dendrimer-based carriers for 177Lu delivery, since normal-organ sparing depends on preserving receptor selectivity rather than simply maximizing tumor accumulation.

4.3. Liposomes and Lipid-Based Nanoparticles

Lipid-based carriers have been used for both radionuclide delivery and combined photodynamic/radiotherapeutic approaches. As summarized in a recent nanotheranostics review, nanotexaphyrin-lipid self-assemblies capable of chelating both 111In and lutetium have achieved peak tumor uptake of 4.5%ID/g at 8 hours in PSMA-positive xenografts, enabling combined SPECT imaging and photodynamic therapy, while antibody-fragment-conjugated liposomes have achieved 1.6- to 2-fold higher tumor accumulation than non-targeted vesicles, and diabody-conjugated liposomes have reached tumor uptake as high as 15%ID/g [18] 225Ac-labeled liposomes bearing PSMA-targeting urea ligands have likewise demonstrated markedly higher in vitro cell-killing efficacy compared with antibody-targeted vesicles, illustrating the applicability of liposomal platforms to alpha-emitter delivery, discussed further in Section 7[18]

4.4. Polymeric Nanoparticles and Micelles

Amphiphilic block copolymers, particularly PLGA-b-PEG, self-assemble into core-shell nanoparticles with a hydrophobic drug-loaded core and a PEGylated corona that can be functionalized with PSMA aptamers or small-molecule ligands [18] Studies in PSMA-positive xenografts summarized in the nanotheranostics literature show that targeting-ligand density critically affects pharmacokinetics: an aptamer density of approximately 5% produced maximal tumor uptake, whereas higher densities (10%) paradoxically reduced tumor accumulation, attributed to altered particle opsonization and a payload burst effect [18] In a broader review of prostate cancer nanomedicines, PSMA-aptamer-functionalized polymeric nanoparticles carrying docetaxel have likewise shown improved tumor cell uptake and apoptosis relative to non-targeted controls, and aptamer-conjugated nanobubbles loaded with paclitaxel have achieved approximately 50% greater apoptosis than free paclitaxel in vitro, in addition to functioning as ultrasound contrast agents [26]

4.5. Iron Oxide and Magnetic Nanoparticles

Superparamagnetic iron oxide nanoparticles functionalized with PSMA-targeting ligands enable combined PET/MRI imaging of PSMA-expressing tumors [18]. Bajwa and colleagues developed bispecific, radiolabeled iron oxide nanoparticles co-functionalized with PSMA and bombesin (BN, a gastrin-releasing-peptide-receptor-binding) ligands for dual-targeting of prostate cancer, an approach designed to address the tumor heterogeneity limitation described in Section 2.3 by engaging two independent, complementary molecular targets on the same particle [24]

A particularly notable 2025 development combined a magnetic Mn0.6Zn0.4Fe2O4 nanoparticle core with a thermosensitive liposome shell carrying siRNA against the transcription factor YY1 and a PSMA-targeting glutamate-urea-lysine surface ligand (GUL@LsiYY1@MZ) [25] Under an externally applied alternating magnetic field, this nanoplatform released its siRNA payload in a spatiotemporally controlled manner, silencing YY1, suppressing the cystine/glutamate antiporter SLC7A11, and triggering iron-dependent lipid peroxidation (ferroptosis) selectively in PSMA-expressing prostate cancer cells, while simultaneously functioning as a T2-weighted MRI contrast agent (r2 = 206 mM-1 s-1) [25] In vitro, cell viability fell to 11% with combined nanoparticle treatment and magnetic field activation, versus 87% in untreated controls, with corresponding tumor growth inhibition in vivo [25] Although this system does not itself carry lutetium-177, it exemplifies the kind of externally triggerable, PSMA-targeted, multimodal nanoplatform that could in principle be paired with, or evolved toward, radionuclide co-delivery alongside Pluvicto.

4.6. Aptamer-Functionalized Nanocarriers and Translational Caveats

PSMA-binding RNA aptamers, most commonly the A10-3.2 aptamer, offer an alternative to small-molecule or antibody-based targeting, with advantages in synthetic reproducibility and reduced immunogenicity [26] A recent updated review of prostate cancer nanomedicines cautions, however, that most reported platforms -- aptamer-based systems included -- remain confined to laboratory and animal studies, and identifies reproducibility of nanoparticle synthesis and control of in vivo biodistribution as persistent, unresolved barriers across the field [26] underscoring the importance of rigorous, independently reproduced preclinical data before translational claims are made about any PSMA-targeted nanocarrier, including those discussed in this review.

Summary of Representative Platforms

Platform	PSMA Ligand	Radionuclide / Payload	Key Reported Outcome	Source
Gold nanoparticle (~20 nm)	Thiolated PSMA peptide	177Lu (TADOTAGA chelator)	98.6% labeling yield; PSMA-selective LNCaP killing in vitro	[19]
G4 PAMAM dendrimer	ACUPA	Imaging/drug carrier	Extended blood half-life; PSMA-selective xenograft uptake	[20]
PAMAM dendrimer-drug conjugate	PSMA-targeting moiety	Small-molecule drug	Preclinical efficacy in prostate cancer models	[21]
2-Deoxyglucose dendrimer	PSMA-targeting moiety	2-Deoxyglucose	Combined PSMA targeting with glycolysis disruption	[22]
Triazine dendrimer (G1-G5)	DUPA (4-64 copies)	Imaging	High valency (G5) loses PSMA selectivity via EPR dominance	[18]
Nanotexaphyrin-lipid nanoparticle	PSMA urea ligand	111In / Lu, photodynamic therapy	4.5%ID/g peak tumor uptake at 8 h	[18]
Antibody-fragment liposome	scFv / diabody	Imaging	1.6-2x (scFv) to 15%ID/g (diabody) tumor accumulation	[18]
225Ac-liposome	PSMA urea ligand	225Ac	Higher in vitro cell killing vs. antibody-targeted vesicles	[18]
PLGA-b-PEG micelle	PSMA aptamer	Chemotherapy	Maximal tumor uptake at ~5% ligand density	[18]
Bispecific iron oxide nanoparticle	PSMA + bombesin (BN)	Radiolabel / MRI	Dual-receptor targeting for PSMA-heterogeneous disease	[24]
Melanin-like nanoparticle	PSMA-targeting moiety	Multifunctional theranostic	Multifunctional nanoplatform for prostate cancer theranostics	[23]
GUL@LsiYY1@MZ magnetic nanoparticle	Glutamate-urea-lysine (GUL)	siRNA / MRI contrast	Viability 11% vs. 87% control; ferroptosis induction	[25]

5. Combination Strategies: Radiosensitization and Multimodal Adjuncts

A second, mechanistically distinct strand of research uses nanoparticles not as carriers of the therapeutic radionuclide itself, but as radiosensitizers or combination partners administered alongside conventional radioligand therapy. High-atomic-number nanoparticles, particularly gold, are well characterized as radiosensitizers in external-beam radiotherapy; extending this concept specifically to internal radionuclide therapy with 177Lu- or 225Ac-PSMA agents is mechanistically plausible but has not been extensively validated in the PSMA-specific literature reviewed here, and represents an identifiable evidence gap rather than an established combination strategy.

The nanoparticle-based combination approaches with the most developed evidence base pair PSMA-targeted nanocarriers with photodynamic therapy, photothermal therapy, or gene silencing, as in the ferroptosis-inducing magnetic nanoplatform described in Section 4.5, rather than with the 177Lu beta-emitter itself [18,25] This suggests that the nearest-term translational opportunity for nanoparticle-radioligand combination therapy may lie in multimodal regimens -- for instance, a PSMA-targeted nanoparticle delivering a radiosensitizing or DNA-repair-inhibiting payload administered around the time of a standard Pluvicto infusion cycle -- rather than in a fully integrated nanoparticle-radionuclide single agent, at least in the near term.

6. Addressing Off-Target Toxicity: Nanotechnology and Pharmacologic Radioprotective Strategies

Xerostomia and, to a lesser degree, nephrotoxicity remain the most clinically significant off-target effects of PSMA radioligand therapy [13], with a recent narrative review reporting xerostomia in approximately 38.8% of patients treated with 177Lu-PSMA-617 (predominantly mild-to-moderate) versus a substantially higher and more treatment-limiting incidence with 225Ac-PSMA regimens [8]

Two complementary strategies are being pursued to mitigate this toxicity. The first is pharmacologic: botulinum toxin combined with scopolamine has been investigated as a protective strategy against salivary gland toxicity in patients receiving 225Ac- and 177Lu-PSMA radioligand therapy, with early data showing mean reductions in radioligand uptake of approximately 30% in parotid glands and 17% in submandibular glands [17] and structural or pharmacokinetic modifications to the PSMA ligand itself have been proposed to reduce salivary and renal uptake of small-molecule PSMA radiopharmaceuticals at the design stage [14]

The second, more nanotechnology-specific strategy is indirect: because nanoparticle biodistribution is governed by particle size, surface charge, and opsonization rather than by PSMA-receptor pharmacology in normal salivary and renal tissue in the same way as a freely diffusible small molecule, appropriately sized and surface-engineered nanocarriers may in principle achieve lower off-target salivary and renal accumulation than free 177Lu-PSMA-617, even before considering active targeting. This remains, however, a largely theoretical advantage in the PSMA-radioligand context; the albumin-binding ligand data reviewed in Section 2.3 -- a roughly 3.3-fold increase in renal dose despite improved tumor uptake -- is a cautionary example showing that pharmacokinetic modification alone, without deliberate renal-sparing design, can worsen rather than improve the normal-tissue dose profile [15] Any nanoparticle platform proposed as a Pluvicto-adjacent or Pluvicto-replacing therapy will need dedicated organ-level dosimetry studies, not merely tumor-uptake data, to establish a genuine therapeutic-index benefit [16]

7. Nanoparticle Approaches Alongside Emerging Alpha-Emitter (225Ac) PSMA Therapy

Actinium-225-labeled PSMA ligands are an actively investigated alternative and adjunct to 177Lu-PSMA-617, exploiting the high linear energy transfer and short (50-100 micrometer) tissue penetration range of alpha particles to achieve potent cytotoxicity, including in tumors that have progressed after beta-emitter therapy [8] A systematic review and meta-analysis of 225Ac-PSMA-targeted alpha therapy reports PSA decline in the majority of treated patients across pooled studies, though no completed phase III trial yet exists for this modality, and xerostomia is reported as more frequent and often treatment-limiting compared with 177Lu-PSMA-617[8,12]

Nanoparticle carriers are mechanistically well suited to alpha-emitter delivery for an additional reason beyond those discussed in Section 3: alpha-decay can generate recoiling daughter radionuclides that may detach from a small-molecule chelator and redistribute to normal tissue, a recognized theoretical concern for free 225Ac-PSMA ligands, whereas encapsulation within a nanoparticle matrix has been proposed as a strategy to retain daughter nuclides within the carrier and thereby reduce off-target redistribution [18] The 225Ac-labeled, PSMA-targeted liposomes noted in Section 4.3, which achieved markedly higher in vitro cytotoxicity than antibody-targeted vesicles, represent an early example of this approach, though in vivo daughter-nuclide retention and normal-organ dosimetry data for such constructs remain limited in the published literature and are an important area for further study [18]

8. Translational Challenges and Regulatory Considerations

Despite an active and growing preclinical literature, no nanoparticle-based reformulation of 177Lu-PSMA-617 has yet entered clinical trials. An updated review of nanomedicines in prostate cancer explicitly identifies the translational barriers that apply here: difficulty achieving homogeneous, reproducible nanoparticle synthesis at scale; limited ability to precisely control in vivo biodistribution; potential for unintended nanoparticle accumulation in the kidneys, joints, and reticuloendothelial organs; incomplete biodegradation of some inorganic and polymeric scaffolds; and, for the most complex constructs, the cost and regulatory burden of good manufacturing practice (GMP)-compliant production [26]

Radiolabeled nanomedicines face an additional layer of complexity relative to nanoparticle drug carriers generally: radiochemical stability of the nanoparticle-chelator-radionuclide linkage must be maintained not only in vitro but across the full in vivo circulation time of the (typically longer-circulating) nanoparticle, since any dissociation of 177Lu or 225Ac from the carrier would redistribute free radionuclide to normal tissue, potentially negating the intended therapeutic-index benefit. Regulatory pathways for combination radionuclide-nanoparticle products are also less well established than those for either radiopharmaceuticals or nanoparticle drugs individually, and will likely require dedicated dosimetry, chemistry-manufacturing-controls, and long-term biodistribution/clearance data that address the fate of the nanoparticle scaffold itself, not only the radionuclide.

A further consideration specific to this literature is the heterogeneity of the evidence base itself: the majority of high-quality preclinical data described in Section 4, Section 5, Section 6 and Section 7 pertains to PSMA-targeted nanoparticles carrying imaging radiometals, chemotherapeutics, or gene-silencing payloads, with comparatively few studies -- most notably the 2026 gold nanoparticle work and select liposomal 225Ac constructs -- directly incorporating a therapeutic radionuclide matched to the beta- or alpha-emitter classes used clinically in Pluvicto or its alpha-emitting counterparts [18,19] Readers and prospective investigators should therefore interpret the nanoparticle-PSMA literature as establishing proof-of-concept targeting and multimodal design principles rather than as a mature therapeutic pipeline directly competing with or extending Pluvicto in the near term.

9. Future Directions

Direct 177Lu-nanoparticle conjugates with in vivo validation. Building on the 2026 gold nanoparticle proof-of-concept, priority should be given to in vivo biodistribution, tumor-to-normal-organ dosimetry, and efficacy studies of 177Lu-radiolabeled nanoparticles bearing the PSMA-617 (or a closely related) targeting ligand, directly benchmarked against free 177Lu-PSMA-617[19]

Dual-target nanoparticles for PSMA-heterogeneous disease. Bispecific nanoparticles co-targeting PSMA and a second marker, as already demonstrated for PSMA/bombesin-functionalized iron oxide imaging agents, could extend radioligand-therapy benefit to patients with PSMA-low or discordant metastases, a population currently underserved by ligand-based targeting alone [24]

Rationally designed valency and size to preserve selectivity. The triazine dendrimer data showing loss of PSMA selectivity at high generation and valency should inform the design of any new nanoparticle-radionuclide construct; systematic size and valency optimization, rather than maximization of tumor uptake alone, should be a standard preclinical endpoint [18]

Daughter-nuclide retention for alpha-emitter nanocarriers. Given the theoretical redistribution risk of 225Ac daughter nuclides, nanoparticle matrices are engineered specifically to retain recoil daughters, warranting dedicated in vivo dosimetry studies as a potential safety advantage over free 225Ac-PSMA ligands [12]

Combination with radioprotective and radiosensitizing agents. Early-phase work such as the TANDEM PSMA-RLT approach (botulinum toxin/scopolamine for salivary gland protection) should be extended to explore whether nanoparticle-based, PSMA-sparing delivery of radioprotectants or DNA-repair inhibitors can further improve the therapeutic index of standard Pluvicto regimens [17]

Standardized, comparative dosimetry reporting. Future preclinical nanoparticle-PSMA studies should report full organ-level dosimetry (tumor, kidney, salivary gland, bone marrow), not tumor uptake alone, to allow direct therapeutic-index comparison with the well-characterized dosimetry profile of free 177Lu-PSMA-617[16]

10. Conclusion

Lutetium Lu 177 vipivotide tetraxetan has established radioligand therapy as a core modality in the management of PSMA-positive prostate cancer, with an expanding indication now reaching into hormone-sensitive disease [5,6] Its clinical benefit is nonetheless bounded by the pharmacokinetic behavior of a small, rapidly cleared molecule: modest tumor dwell time, dose-limiting off-target uptake in the salivary glands and kidneys, and reduced efficacy in patients with heterogeneous PSMA expression [11,13]

Nanoparticle engineering offers a coherent set of design principles -- prolonged circulation, multivalent and dual-receptor targeting, multimodal payload integration, and potential radioprotective biodistribution -- that map directly onto these limitations, and a substantial and rapidly growing preclinical literature spanning gold nanoparticles, dendrimers, liposomes, polymeric micelles, and magnetic nanoparticles has demonstrated proof-of-concept PSMA-selective targeting, imaging, and, in select recent studies, direct radionuclide delivery [18,19,25] However, the field remains predominantly preclinical, and direct integration with the 177Lu-PSMA-617 construct used in Pluvicto itself is only beginning to be demonstrated in vivo [26] Closing the gap between this promising nanomedicine toolkit and a clinically deployable, dosimetrically validated nanoparticle-radioligand therapy will require sustained investment in reproducible manufacturing, comparative organ-level dosimetry, and dedicated regulatory pathways -- work that, if successful, could meaningfully extend the reach and improve the therapeutic index of PSMA-targeted radioligand therapy beyond what small-molecule agents like Pluvicto can achieve alone.