Rationally Designed Aberrant Kinase-Targeted Endogenous Protein Nanomedicine against Oncogene Mutated/Amplified Refractory Chronic Myeloid Leukemia

Abstract

Deregulated protein kinases play a very critical role in tumorigenesis, metastasis, and drug resistance of cancer. Although molecularly targeted small molecule kinase inhibitors (SMI) are effective against many types of cancer, point mutations in the kinase domain impart drug resistance, a major challenge in the clinic. A classic example is chronic myeloid leukemia (CML) caused by BCR-ABL fusion protein, wherein a BCR-ABL kinase inhibitor, imatinib (IM), was highly successful in the early chronic phase of the disease, but failed in the advanced stages due to amplification of oncogene or point mutations in the drug-binding site of kinase domain. Here, by identifying critical molecular pathways responsible for the drug-resistance in refractory CML patient samples and a model cell line, we have rationally designed an endogenous protein nanomedicine targeted to both cell surface receptors and aberrantly activated secondary kinase in the oncogenic network. Molecular diagnosis revealed that, in addition to point mutations and amplification of oncogenic BCR-ABL kinase, relapsed/refractory patients exhibited significant activation of STAT5 signaling with correlative overexpression of transferrin receptors (TfR) on the cell membrane. Accordingly, we have developed a human serum albumin (HSA) based nanomedicine, loaded with STAT5 inhibitor (sorafenib), and surface conjugated the same with holo-transferrin (Tf) ligands for TfR specific delivery. This dual-targeted "transferrin conjugated albumin bound sorafenib" nanomedicine (Tf-nAlb-Soraf), prepared using aqueous nanoprecipitation method, displayed uniform spherical morphology with average size of ∼150 nm and drug encapsulation efficiency of ∼74%. TfR specific uptake and enhanced antileukemic activity of the nanomedicine was found maximum in the most drug resistant patient sample having the highest level of STAT5 and TfR expression, thereby confirming the accuracy of our rational design and potential of dual-targeting approach. The nanomedicine induced downregulation of key survival pathways such as pSTAT5 and antiapoptotic protein MCL-1 was demonstrated using immunoblotting. This study reveals that, by implementing molecular diagnosis, personalized nanomedicines can be rationally designed and nanoengineered by imparting therapeutic functionality to endogenous proteins to overcome clinically important challenges like molecular drug resistance.

Iron and leukemia: new insights for future treatments

“…Conjugating artemisinin to a TfR targeting peptide shows anti-leukemia activity with a significantly improved leukemia cell selectivity [128]. With the development of technology, some carriers have been developed to link ligands and therapeutic agents for improving the efficacy and safety in therapeutic agent delivery, among which liposomes, dendritic molecules and nanoparticles have been widely used [129, 130]. A human serum albumin based nanomedicine, which is loaded with sorafenib and conjugated ligands for TfR specific delivery, can play enhanced anti-leukemia activity in drug resistant CML patient samples [130].…”

“…With the development of technology, some carriers have been developed to link ligands and therapeutic agents for improving the efficacy and safety in therapeutic agent delivery, among which liposomes, dendritic molecules and nanoparticles have been widely used [129, 130]. A human serum albumin based nanomedicine, which is loaded with sorafenib and conjugated ligands for TfR specific delivery, can play enhanced anti-leukemia activity in drug resistant CML patient samples [130]. The sensitivity of leukemia cells to imatinib can also be enhanced by encapsulated with TfR targeted liposomes [131].…”

Signal Transduction Therapies for Treatment of Chronic Leukemias

“…As a result, pSTAT5 and antiapoptotic protein MCL-1 expressions were inhibited. This study revealed that, combining molecular diagnosis and personalized nanomedicines could have therapeutic functionality to endogenous proteins to overcome clinically important challenges like molecular drug resistance [120]. All these studies point out the importance of STAT5 from JAK/STAT pathway in CML treatment.…”

Mechanism of resistance to tyrosine kinase inhibitors - A case report and review

“…Patients need to be monitored every 3 months but in the case of serious patients monitoring need to be done every month. [1,5] Even though our patient was tested positive for BCR-ABL mutations, it is not known whether the mutation developed initially or after treatment with TKIs. Earlier detection of specific mutations might have prompted immediate new generation TKI therapy.…”