Growth of Metastatic Triple-Negative Breast Cancer Is Inhibited by Deep Tumor-Penetrating and Slow Tumor-Clearing Chemotherapy: The Case of Tumor-Adhering Liposomes with Interstitial Drug Release

Surface-functionalised polymeric nanoparticles for breast cancer treatment: processes and advances

The World Health Organization (WHO) reported that of all the non-communicable diseases, cancer is considered the second cause of death worldwide. This has driven the big pharma companies to prioritise anticancer products in their pipeline. In addition, research has focused on exploration of new anticancer molecules and design of suitable dosage forms to achieve effective drug delivery to the tumour site. Nanotechnology is a valuable tool to build nano delivery systems with controlled and targeted drug release properties. Nanoparticles can be fabricated by robust, scalable and economic techniques using various polymers. Moreover, specific functional groups can be introduced to the surface of nanoparticles enabling targeting to a specific tissue; besides, they exhibit versatile drug release patterns according to the rate of polymer degradation. This review outlines the processes and advances in surface functionalisation of nanoparticles employed for treatment of breast cancer. The therapeutic molecules, the polymers used to fabricate nanoparticles, the techniques used to prepare the nanoparticles have been reviewed with a focus on the processes employed to functionalise these nanoparticles with suitable ligands to target different types of breast cancer.

Combined, yet separate: cocktails of carriers (not drugs) for actinium-225 α-particle therapy of solid tumors expressing moderate-to-low levels of targetable markers

Alpha-particle radionuclide-antibody conjugates are being clinically evaluated against solid tumors even when they moderately express the targeted markers. At this limit of lower tumor-absorbed doses, to maintain efficacy, the few(er) intratumorally delivered alpha-particles need to traverse/hit as many different cancer cells as possible. We complement antibody-radioconjugate therapies with a separate nanocarrier delivering a fraction of the same total injected radioactivity to tumor regions geographically different than those affected by targeting antibodies; these carrier-cocktails collectively distribute the alpha-particle emitters better.

METHODS

The efficacy of actinium-225 delivered by our carrier-cocktails was assessed in vitro and on mice with orthotopic MDA-MB-436 and/or MDA-MB-231 triple-negative breast cancers and/or an ectopic BxPC3 pancreatic cancer. Cells/tumors were chosen to express low-to-moderate levels of HER1, as model antibody-targeted marker.

RESULTS

Independent of cell line, antibody-radioconjugates were most lethal on cell monolayers. On spheroids, with radii greater than alpha-particles' range, carrier-cocktails improved killing efficacy (p < 0.0500). Treatment with carrier-cocktails decreased the MDA-MB-436 and MDA-MB-231 orthotopic tumor volumes by 73.7% and 72.1%, respectively, relative to treatment with antibody-radioconjugates alone, at same total injected radioactivity; these carrier-cocktails completely eliminated formation of spontaneous metastases vs. 50% and 25% elimination in mice treated with antibody-radioconjugates alone. In BxPC3 tumor-bearing mice, carrier-cocktails increased the median survival to 25-26 days (in male-female animals) vs. 20-21 days of mice treated with antibody-radioconjugates alone (vs. 17 days for non-treated animals). Survival with carrier-cocktail radiotherapy was further prolonged by pre-injecting low-dose, standard-of-care, gemcitabine (p = 0.0390).

CONCLUSION

Tumor-agnostic carrier-cocktails significantly enhance the therapeutic efficacy of existing alpha-particle radionuclide-antibody treatments.

Meta-Analysis of Nanoparticle Distribution in Tumors and Major Organs in Tumor-Bearing Mice

Low tumor delivery efficiency is a critical barrier in cancer nanomedicine. This study reports an updated version of "Nano-Tumor Database", which increases the number of time-dependent concentration data sets for different nanoparticles (NPs) in tumors from the previous version of 376 data sets with 1732 data points from 200 studies to the current version of 534 data sets with 2345 data points from 297 studies published from 2005 to 2021. Additionally, the current database includes 1972 data sets for five major organs (i.e., liver, spleen, lung, heart, and kidney) with a total of 8461 concentration data points. Tumor delivery and organ distribution are calculated using three pharmacokinetic parameters, including delivery efficiency, maximum concentration, and distribution coefficient. The median tumor delivery efficiency is 0.67% injected dose (ID), which is low but is consistent with previous studies. Employing the best regression model for tumor delivery efficiency, we generate hypothetical scenarios with different combinations of NP factors that may lead to a higher delivery efficiency of >3%ID, which requires further experimentation to confirm. In healthy organs, the highest NP accumulation is in the liver (10.69%ID/g), followed by the spleen 6.93%ID/g and the kidney 3.22%ID/g. Our perspective on how to facilitate NP design and clinical translation is presented. This study reports a substantially expanded "Nano-Tumor Database" and several statistical models that may help nanomedicine design in the future.

Predicting response of micrometastases with MIRDcell V3: proof of principle with 225Ac-DOTA encapsulating liposomes that produce different activity distributions in tumor spheroids

PURPOSE

The spatial distribution of radiopharmaceuticals within multicellular clusters is known to have a significant effect on their biological response. Most therapeutic radiopharmaceuticals distribute nonuniformly in tissues which makes predicting responses of micrometastases challenging. The work presented here analyzes published temporally dependent nonuniform activity distributions within tumor spheroids treated with actinium-225-DOTA encapsulating liposomes (225Ac-liposomes) and uses these data in MIRDcell V3.11 to calculate absorbed dose distributions and predict biological response. The predicted responses are compared with experimental responses.

METHODS

Four types of liposomes were prepared having membranes with different combinations of release (R) and adhesion (A) properties. The combinations were R-A-, R-A+, R+A-, and R+A+. These afford different penetrating properties into tissue. The liposomes were loaded with either carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) or 225Ac. MDA-MB-231 spheroids were treated with the CFDA-SE-liposomes, harvested at different times, and the time-integrated CFDA-SE concentration at each radial position within the spheroid was determined. This was translated into mean 225Ac decays/cell versus radial position, uploaded to MIRDcell, and the surviving fraction of cells in spherical multicellular clusters was simulated. The MIRDcell-predicted surviving fractions were compared with experimental fractional-outgrowths of the spheroids following treatment with 225Ac-liposomes.

RESULTS

The biological responses of the multicellular clusters treated with 225Ac-liposomes with physicochemical properties R+A+, R-A+, and R-A- were predicted by MIRDcell with statistically significant accuracy. The prediction for R+A- was not predicted accurately.

CONCLUSION

In most instances, MIRDcell predicts responses of spheroids treated with 225Ac-liposomes that result in different tissue-penetrating profiles of the delivered radionuclides.

Combination of Carriers with Complementary Intratumoral Microdistributions of Delivered -Particles May Realize the Promise for 225Ac in Large, Solid Tumors

α-particle radiotherapy has already been shown to be impervious to most resistance mechanisms. However, in established (i.e., large, vascularized) soft-tissue lesions, the diffusion-limited penetration depths of radiolabeled antibodies or nanocarriers (≤50-80 μm) combined with the short range of α-particles (4-5 cell diameters) may result in only partial tumor irradiation, potentially limiting treatment efficacy. To address this challenge, we combined carriers with complementary intratumoral microdistributions of the delivered α-particles. We used the α-particle generator ²²⁵Ac, and we combined a tumor-responsive liposome (which, on tumor uptake, releases into the interstitium a highly diffusing form of its radioactive payload [²²⁵Ac-DOTA], potentially penetrating the deeper parts of tumors where antibodies do not reach) with a separately administered, less-penetrating radiolabeled antibody (irradiating the tumor perivascular regions where liposome contents clear too quickly). Methods: In a murine model with orthotopic human epidermal growth factor receptor 2-positive BT474 breast cancer xenografts, the biodistributions of each carrier were evaluated, and the control of tumor growth was monitored after administration of the same total radioactivity of ²²⁵Ac delivered by the ²²⁵Ac-DOTA-encapsulating liposomes, by the ²²⁵Ac-DOTA-SCN--labeled trastuzumab, and by both carriers at equally split radioactivities. Results: Tumor growth was significantly more inhibited when the same total injected radioactivity was divided between the 2 separate carriers than when delivered by either of the carriers alone. The combined carriers enabled more uniform intratumoral microdistributions of α-particles, at a tumor dose that was lower than the dose delivered by the antibody alone. Conclusion: This strategy demonstrates that more uniform microdistributions of the delivered α-particles within established solid tumors improve efficacy even at lower tumor doses. Augmentation of antibody-targeted α-particle therapies with tumor-responsive liposomes may address partial tumor irradiation, improving therapeutic effects.

Two diverse carriers are better than one: A case study in α‐particle therapy for prostate specific membrane antigen‐expressing prostate cancers

Partial and/or heterogeneous irradiation of established (i.e., large, vascularized) tumors by α‐particles that exhibit only a 4–5 cell‐diameter range in tissue, limits the therapeutic effect, since regions not being hit by the high energy α‐particles are likely not to be killed. This study aims to mechanistically understand a delivery strategy to uniformly distribute α‐particles within established solid tumors by simultaneously delivering the same α‐particle emitter by two diverse carriers, each killing a different region of the tumor: (1) the cancer‐agnostic, but also tumor‐responsive, liposomes engineered to best irradiate tumor regions far from the vasculature, and (2) a separately administered, antibody, targeting any cancer‐cell's surface marker, to best irradiate the tumor perivascular regions. We demonstrate that on a prostate specific membrane antigen (PSMA)‐expressing prostate cancer xenograft mouse model, for the same total injected radioactivity of the α‐particle emitter Actinium‐225, any radioactivity split ratio between the two carriers resulted in better tumor growth inhibition compared to the tumor inhibition when the total radioactivity was delivered by any of the two carriers alone. This finding was due to more uniform tumor irradiation for the same total injected radioactivity. The killing efficacy was improved even though the tumor‐absorbed dose delivered by the combined carriers was lower than the tumor‐absorbed dose delivered by the antibody alone. Studies on spheroids with different receptor‐expression, used as surrogates of the tumors' avascular regions, demonstrated that our delivery strategy is valid even for as low as 1+ (ImmunoHistoChemistry score) PSMA‐levels. The findings presented herein may hold clinical promise for those established tumors not being effectively eradicated by current α‐particle radiotherapies.

Growth Inhibition of Triple-Negative Breast Cancer: The Role of Spatiotemporal Delivery of Neoadjuvant Doxorubicin and Cisplatin

Combinations of platinum-based compounds with doxorubicin in free and/or in liposomal form for improved safety are currently being evaluated in the neoadjuvant setting on patients with advanced triple-negative breast cancer (TNBC). However, TNBC may likely be driven by chemotherapy-resistant cells. Additionally, established TNBC tumors may also exhibit diffusion-limited transport, resulting in heterogeneous intratumoral delivery of the administered therapeutics; this limits therapeutic efficacy in vivo. We studied TNBC cells with variable chemosensitivities, in the absence (on monolayers) and presence (in 3D multicellular spheroids) of transport barriers; we compared the combined killing effect of free doxorubicin and free cisplatin to the killing effect (1) of conventional liposomal forms of the two chemotherapeutics, and (2) of tumor-responsive lipid nanoparticles (NP), specifically engineered to result in more uniform spatiotemporal microdistributions of the agents within solid tumors. This was enabled by the NP properties of interstitial release, cell binding/internalization, and/or adhesion to the tumors’ extracellular matrix. The synergistic cell kill by combinations of the agents (in all forms), compared to the killing effect of each agent alone, was validated on monolayers of cells. Especially for spheroids formed by cells exhibiting resistance to doxorubicin combination treatments with both agents in free and/or in tumor-responsive NP-forms were comparably effective; we not only observed greater inhibition of outgrowth compared to the single agent(s) but also compared to the conventional liposome forms of the combined agents. We correlated this finding to more uniform spatiotemporal microdistributions of agents by the tumor-responsive NP. Our study shows that combinations of NP with properties specifically optimized to improve the spatiotemporal uniformity of the delivery of their corresponding therapeutic cargo can improve treatment efficacy while keeping favorable safety profiles.

Transport-driven engineering of liposomes for delivery of α-particle radiotherapy to solid tumors: effect on inhibition of tumor progression and onset delay of spontaneous metastases

PURPOSE

Highly cytotoxic α-particle radiotherapy delivered by tumor-selective nanocarriers is evaluated on metastatic Triple Negative Breast Cancer (TNBC). On vascularized tumors, the limited penetration of nanocarriers (<50-80 μm) combined with the short range of α-particles (40-100 μm) may, however, result in only partial tumor irradiation, compromising efficacy. Utilizing the α-particle emitter Actinium-225 (²²⁵Ac), we studied how the therapeutic potential of a general delivery strategy using nanometer-sized engineered liposomes was affected by two key transport-driven properties: (1) the release from liposomes, when in the tumor interstitium, of the highly diffusing ²²⁵Ac-DOTA that improves the uniformity of tumor irradiation by α-particles and (2) the adhesion of liposomes on the tumors' ECM that increases liposomes' time-integrated concentrations within tumors and, therefore, the tumor-delivered radioactivities.

METHODS

On an orthotopic MDA-MB-231 TNBC murine model forming spontaneous metastases, we evaluated the maximum tolerated dose (MTD), biodistributions, and control of tumor growth and/or spreading after administration of ²²⁵Ac-DOTA-encapsulating liposomes, with different combinations of the two transport-driven properties.

RESULTS

At 83% of MTD, ²²⁵Ac-DOTA-encapsulating liposomes with both properties (1) eliminated formation of spontaneous metastases and (2) best inhibited the progression of orthotopic xenografts, compared to liposomes lacking one or both properties. These findings were primarily affected by the extent of uniformity of the intratumoral microdistributions of ²²⁵Ac followed by the overall tumor uptake of radioactivity. At the MTD, long-term toxicities were not detected 9.5 months post administration.

CONCLUSION

Our findings demonstrate the potential of a general, transport-driven strategy enabling more uniform and prolonged solid tumor irradiation by α-particles without cell-specific targeting.

Daptomycin-Induced Lipid Phases on Model Lipid Bilayers: Effect of Lipid Type and of Lipid Leaflet Order on Membrane Permeability

Daptomycin's bacterial membrane activity is partly due to the defects of lipid-packing at the boundaries of daptomycin-induced, separated lipid phases, which are rich in phosphatidylglycerol (PG). On model membranes, the permeability of phase boundaries is strongly dependent on the extent of saturation of the lipid acyl tails, which affect the lipids' ability to pack within these boundaries, and on the cross-leaflet registration of these boundaries. Using vesicles with asymmetric lipid leaflet compositions, we evaluated the role of headgroup type and/or extent of acyl-tail saturation on daptomycin-induced membrane permeability. We demonstrate that the release rates of vesicle-encapsulated contents scales with the total length of daptomycin-induced, PG-rich phase boundaries. On the outer leaflet, lipids with PG-headgroups (in contact with daptomycin) were a necessary condition, but they still were not adequate for release. Increased membrane permeability was observed only when inner leaflet lipids had saturated acyl tails; we postulate that the latter may have enabled the recruitment, by the outer leaflet daptomycin-induced phases, of inner leaflet lipids in cross-registered phases with boundaries of defective packing that spanned the bilayer. These findings provide insights on the potential role of lipids as a whole (headgroup and acyl tails) and of lipid leaflet order on the boundaries of daptomycin-induced separated lipid phases in model membranes.

Harnessing Extracellular Matrix Biology for Tumor Drug Delivery

The extracellular matrix (ECM) plays an active role in cell life through a tightly controlled reciprocal relationship maintained by several fibrous proteins, enzymes, receptors, and other components. It is also highly involved in cancer progression. Because of its role in cancer etiology, the ECM holds opportunities for cancer therapy on several fronts. There are targets in the tumor-associated ECM at the level of signaling molecules, enzyme expression, protein structure, receptor interactions, and others. In particular, the ECM is implicated in invasiveness of tumors through its signaling interactions with cells. By capitalizing on the biology of the tumor microenvironment and the opportunities it presents for intervention, the ECM has been investigated as a therapeutic target, to facilitate drug delivery, and as a prognostic or diagnostic marker for tumor progression and therapeutic intervention. This review summarizes the tumor ECM biology as it relates to drug delivery with emphasis on design parameters targeting the ECM.

Cognitive Dysfunction and Neurophysiologic Mechanism of Breast Cancer Patients Undergoing Chemotherapy Based on Resting State Functional Magnetic Resonance Imaging

We studied chemotherapy-related cognitive impairment via resting state (RS)-functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in 19 cases of patients with early breast cancer. White matter neuropsychological test treatment were carried out before and after chemotherapy, RS-fMRI, and DTI evaluation. In RS-fMRI with regional homogeneity (ReHo) reflects brain activity. In the DTI with fractional anisotropy (FA) reflect the integrity of the white matter. Determining the region of interest by image analysis, we calculated the neuropsychologic test score using the paired t-test and FA change ReHo values of regions of interest. Finally after the test treatment, in the chemotherapy group for pairing correlation analysis t-test scores change in meaningful inspection and change ReHo and FA. Chemotherapy after chemotherapy than before chemotherapy difference memory test and self-evaluation of cognitive (P < 0.05). ReHo value increases occurred in the right orbitofrontal region and the left dorsolateral prefrontal cortex. Declines in brain regions were the anterior inferior cerebellar lobe, cerebellar lobe, right middle temporal gyrus and the superior temporal gyrus, the lower right of the center area, and the central gyrus. This prospective study on resting state and RS-fMRI functional magnetic resonance DTI study DTI sequence combination chemotherapy for breast cancer-related cognitive disorders supports the "chemo brain" point of view. Chemotherapy can cause memory decline, accompanied by a partial area of the brain and white matter integrity in brain activity changes. Prompt clinical treatment RS-fMRI and DTI have potential applications in assessing chemotherapy-related cognitive impairment.