Periodic Reporting for period 4 - NANONC (Nanomaterials in Oncology: Exploiting the Intrinsic Cancer-Specific Toxicity of Nanoparticles.)
Reporting period: 2022-07-01 to 2022-12-31
In our current society, therapeutic strategies against cancer suffer from dose-limiting toxicity, lack of specificity and high morbidity. To overcome this, the use of nanomaterials (NMs) is rising, where several NM formulations are undergoing clinical trials or are used in clinics where the NMs are used as drug delivery vehicles or as mediators in physical anticancer methods (e.g. hyperthermia), where to date, the success rate is limited due to low tumor targeting efficacy, lack of specificity and frequent re-use of classical toxicity mechanisms.
To overcome these issues, this research program aims to exploit the intrinsic toxicity of certain types of metal-based, degradation-prone NMs towards only cancer cells as a novel and generic anti-cancer tool with:
improved efficacy against difficult to treat cancers such as multidrug-resistant cancer cells
enhanced specificity and selectivity of the treatment by the intrinsic cancer cell-specific toxicity of NMs towards cancer cells.
These NMs therefore offer high potential against difficult to treat tumor types, where special tumor cells, such as cancer stem cells, which are renowned to be resistant against many types of classical therapy. In doing so, these NMs can be used as a novel therapeutic tool to combat the cells that escape classical treatments.
A major limitation of NM therapy is the poor biodistribution, where intravenously administered NMs struggle to reach the actual tumor site, but mainly end up in other organs, such as liver, spleen, lungs or kidneys. To overcome this problem, many attempts have been made to alter NM properties by changing its surface, either by trying to hide the NMs from immune cells, or by attaching antibodies or small peptides that bind specific epitopes on the cancer cell surface. So far, these attempts have not been very succesful, and here a biological vehicle will be used to try and carry the NMs to the tumor site in an active transport manner, rather than the NM being pushed by the blood stream and entering the tumor by chance. For this, the NMs will be coupled to so-called tumor-homing cells, which upon administration, travel towards the tumor automatically. Control over NM release into the tumor mass will then enable us to signifcantly increase the level of NMs at the tumor site.
The increase in targeted delivery is vital for improving therapeutic efficacy, as more therapeutic agent can be delivered to the site where it is needed, while less therapeutic agent would be present in other areas, reducing any undesired side-effects.
To overcome these issues, this research program aims to exploit the intrinsic toxicity of certain types of metal-based, degradation-prone NMs towards only cancer cells as a novel and generic anti-cancer tool with:
improved efficacy against difficult to treat cancers such as multidrug-resistant cancer cells
enhanced specificity and selectivity of the treatment by the intrinsic cancer cell-specific toxicity of NMs towards cancer cells.
These NMs therefore offer high potential against difficult to treat tumor types, where special tumor cells, such as cancer stem cells, which are renowned to be resistant against many types of classical therapy. In doing so, these NMs can be used as a novel therapeutic tool to combat the cells that escape classical treatments.
A major limitation of NM therapy is the poor biodistribution, where intravenously administered NMs struggle to reach the actual tumor site, but mainly end up in other organs, such as liver, spleen, lungs or kidneys. To overcome this problem, many attempts have been made to alter NM properties by changing its surface, either by trying to hide the NMs from immune cells, or by attaching antibodies or small peptides that bind specific epitopes on the cancer cell surface. So far, these attempts have not been very succesful, and here a biological vehicle will be used to try and carry the NMs to the tumor site in an active transport manner, rather than the NM being pushed by the blood stream and entering the tumor by chance. For this, the NMs will be coupled to so-called tumor-homing cells, which upon administration, travel towards the tumor automatically. Control over NM release into the tumor mass will then enable us to signifcantly increase the level of NMs at the tumor site.
The increase in targeted delivery is vital for improving therapeutic efficacy, as more therapeutic agent can be delivered to the site where it is needed, while less therapeutic agent would be present in other areas, reducing any undesired side-effects.
The project has focussed mainly on identifying the most suitable NMs to be considered for further use in this project. This involves an in-depth study of the toxicity of different NM formulations on findings those conditions where cancer cells are affected maximally while non-cancerous cells would remain unaffected. We have tested a total of 6 different NM series, all of which further contained minor modifications such as the surface coating, size or presence of metal dopants.
For most NMs, we have also already started with testing their therapeutic potential in preclinical animal models. For Fe-doped CuO, this has already been published, where the optimally selected NMs showed a clear and strong but transient effect on tumor viability. To increase the therapeutic efficacy, we have combined with NM with a clinical immunotherapeutic agent, which resulted in a synergistic therapeutic effect, where the tumor finally could be completely overwon in about 60 % of the animals tested. Most interestingly, the combined therapy of NMs with immunotherapeutic regimen resulted in a long-lasting systemic anticancer immune response, where the animals that had been successfully treated were not able to grow the same type of tumor again in a tumor rechallenge model 6 months after the initial treatment.
We have successfully used Cu-doped TiO2 NMs to elicit immune responses against tumor cells, and have also successfully used Fe-doped ZnO NMs to elicit immunogenic cell death and improve the outcome of immunotherapy.
Apart from testing the therapeutic efficacy of the NMs, we have evaluated different methods to improve the delivery of the NMs to solid tumors using tumor-homing cells. We have evaluated different cell types, and various cell labeling strategies to ensure maximal viability of the tumor homing cells. The delivery of the NM-loaded cells to solid tumors has been studied extensively in preclinical tumor models, and we have evaluated the ability to deliver different types of inorganic NMs, including the therapeutic Fe-doped CuO NMs, upon triggering the release of the NMs by the cells using a chemical agent. This has resulted in a strong increase in NM delivery to solid tumors compared to simple administration of the NMs without any tumor homing cells. Together, this has resulted in an efficient therapeutic efficacy in preclinical tumor models.
Taken together, we have evaluated and confirmed the therapeutic potential of doped metaloxide NMs for tumor therapy and have found that these agents are effective in eliciting immunogenic cell death in the tumor cells, while simultaneously activating innate immune cells. This has resulted in a strong enhancement of common immune checkpoint inhibition strategies. While this initially was performed in subcutaneous tumor models where the NMs could be administered directly into the tumor, we have also developed a strategy using tumor-homing cells coupled with the NMs that resulted in a highly efficient delivery of the NMs to the tumor site. These two strategies together promise an efficient novel therapeutic tool our fight against cancer.
For most NMs, we have also already started with testing their therapeutic potential in preclinical animal models. For Fe-doped CuO, this has already been published, where the optimally selected NMs showed a clear and strong but transient effect on tumor viability. To increase the therapeutic efficacy, we have combined with NM with a clinical immunotherapeutic agent, which resulted in a synergistic therapeutic effect, where the tumor finally could be completely overwon in about 60 % of the animals tested. Most interestingly, the combined therapy of NMs with immunotherapeutic regimen resulted in a long-lasting systemic anticancer immune response, where the animals that had been successfully treated were not able to grow the same type of tumor again in a tumor rechallenge model 6 months after the initial treatment.
We have successfully used Cu-doped TiO2 NMs to elicit immune responses against tumor cells, and have also successfully used Fe-doped ZnO NMs to elicit immunogenic cell death and improve the outcome of immunotherapy.
Apart from testing the therapeutic efficacy of the NMs, we have evaluated different methods to improve the delivery of the NMs to solid tumors using tumor-homing cells. We have evaluated different cell types, and various cell labeling strategies to ensure maximal viability of the tumor homing cells. The delivery of the NM-loaded cells to solid tumors has been studied extensively in preclinical tumor models, and we have evaluated the ability to deliver different types of inorganic NMs, including the therapeutic Fe-doped CuO NMs, upon triggering the release of the NMs by the cells using a chemical agent. This has resulted in a strong increase in NM delivery to solid tumors compared to simple administration of the NMs without any tumor homing cells. Together, this has resulted in an efficient therapeutic efficacy in preclinical tumor models.
Taken together, we have evaluated and confirmed the therapeutic potential of doped metaloxide NMs for tumor therapy and have found that these agents are effective in eliciting immunogenic cell death in the tumor cells, while simultaneously activating innate immune cells. This has resulted in a strong enhancement of common immune checkpoint inhibition strategies. While this initially was performed in subcutaneous tumor models where the NMs could be administered directly into the tumor, we have also developed a strategy using tumor-homing cells coupled with the NMs that resulted in a highly efficient delivery of the NMs to the tumor site. These two strategies together promise an efficient novel therapeutic tool our fight against cancer.
We have shown the complete remission of tumors using a simple NM in combination with a immunotherapeutic agent. We are deciphering the precise mechanism in some more details, but these results go far beyond what has been achieved to date in the field of either nanomedicine or immunotherapy. In essence, the formulation we have used seems to be able to enhance the activity of a clinical immunotherapeutic agent in conditions where the immunotherapeutic agent in itself is not sufficiently strong to achieve any major effects. The long-lasting, systemic anticancer immune activation furthermore results in a strong protective therapeutic effect, where the mice were not prone to relapse, even upon rechallenging them with the same tumor type, or where metastases were not detected in any mouse up to a year following initial treatment. This suggests a significant and wide-spread therapeutic effect of the NM-immunotherapy regimen.
We have defined 3 potent formulations, of which the 6% Fe-doped CuO NMs were most efficient in treating cancer. One major impediment to their use is that fact that surface engineering is not recommended as it would impact the therapeutic activity of the NMs. This, however, limits their use as their circulation times are really short, resulting in very poor tumor delivery efficacy upon intravenous administration. As we are able to combine tumor-homing cells with these NMs, and trigger the release of the NMs from the cells, we have found that this can efficiently overcome the problems of poor delivery and result in high levels of tumor-targeted nanoformulations. Together, this result in a strong and potent therapeutic effect and enhancement of immunotherapy strategies that otherwise could not be obtained using the NMs on their own.
We have defined 3 potent formulations, of which the 6% Fe-doped CuO NMs were most efficient in treating cancer. One major impediment to their use is that fact that surface engineering is not recommended as it would impact the therapeutic activity of the NMs. This, however, limits their use as their circulation times are really short, resulting in very poor tumor delivery efficacy upon intravenous administration. As we are able to combine tumor-homing cells with these NMs, and trigger the release of the NMs from the cells, we have found that this can efficiently overcome the problems of poor delivery and result in high levels of tumor-targeted nanoformulations. Together, this result in a strong and potent therapeutic effect and enhancement of immunotherapy strategies that otherwise could not be obtained using the NMs on their own.