CONCLUSION AND PERSPECTIVE
Immunotherapy
is an essential approach to cancer treatment that has high specificity,
long-term efficacy, reduces a large intake of drugs, and provides less
invasive treatment than traditional therapies. Due to special properties
or conjugation with different adjuvants, CDs are developed to inspire
immune response which can be a novel approach to clinical application in
tumor immunotherapy. In this review, we summarize and discuss the
current application of CDs in tumor immunotherapy, including vaccines,
immunoadjuvants,
and synergistic therapy with PDT/PTT/CDT. In general, depending on the
recent progress of CD good absorption in NIR and high ROS generation
caused by CDs surface electronic transitions under light irradiation, it
is rational for CDs to act as important tools in targeted tumor PDT/PTT.
Further, smaller particle size,
variable
surface structure, and easy cell internalization make CDs become great
vehicles for the delivery of chemotherapeutics, such as doxorubicin and
platinum drugs. Nevertheless, it is often difficult to get the ideal
long-term therapeutic effect with monotherapy. To address this, current
studies on tumor therapy by using CDs are moving toward the synergistic
use of multiple treatments, especially combined with immunotherapy. By
ingenious design, CDs are able to elicit an anti-tumor immune response
while performing PDT/PTT/CDT. On the other side, CDs, as presented, are
directly used in tumor
immunotherapy,
namely, as vaccines or immunoadjuvants. Although the application of CDs
in vaccines and immunoadjuvants is still in its infancy, high
biocompatibility and various functional surface groups help CDs to
stimulate the tumor immune response and transform the low immunogenic
“cold tumors” into the high immunogenic “hot tumors”. In addition,
CDs are explored to combine with tumor antigen models, such as OVA, to
perform the dual role of immunoadjuvant and vaccine in tumor therapy.
However, there are also many challenges and clinical translation
concerns of CDs in tumor immunotherapy. Firstly, the pharmacokinetic
changes of CDs in vivo , especially the structure and functional
group changes of CDs are unclear. Clinical application is often holding
a cautious attitude to unclear medicines. Secondly, although most CDs
have lower toxicity and better clearance efficiency in vivo , the
information related to long-term toxicity remains missing since cancer
treatment is a long and cumulative process. Thirdly, the current
efficiency of CDs in immunotherapy has yet to be improved. Enhancing
targeting and reducing side effects are long-term questions of CDs in
immunotherapy. Last but not least, the applications of CDs in tumor
immunotherapy are still in the earlier stages and the therapeutic
experiments are mainly conducted in rodents. Further studies are needed
to translate the results obtained in animal models into human
applications. Collectively, CDs have made remarkable progress in tumor
immunotherapy. The applications of CDs so far are very promising in
tumor immunotherapy. CDs can play a role in directing immune response,
but further investigation is essential to explore their full potential
and revolutionize the future of medicine.