Therapeutic Blood Cancer Vaccine Candidate Identified

Exploration of new leukemia antigens and the construction of appropriate delivery systems using the US Food and Drug Administration approved material are important strategies for developing leukemia vaccines for clinic use.

Leukemia is a cancer of the early blood-forming cells. Most often, leukemia is a cancer of the white blood cells, but some leukemias start in other blood cell types.

Researchers from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences and Zhujiang Hospital of Southern Medical University, have developed a new type of precise therapeutic vaccine against leukemia. 

Announced on October 12, 2020, this leukemia vaccine candidate utilizes self-healing polylactic acid microcapsules for co-encapsulating a new epitope peptide and PD-1 antibody.

Although the possibility of treating leukemia through vaccination has been established, therapeutic performance still falls short of expectations in the clinic.

"Our clinical findings revealed the high expression of EPS8 and PD-1/PD-L1 in leukemia patients, which could be respectively used as a new type of leukemia antigen and a checkpoint target for a leukemia vaccine," said Prof. LI Yuhua from Zhujiang Hospital, in a press release.

In the novel vaccine, epitope peptides and PD-1 antibodies can be simply, mildly, and efficiently loaded into polylactic acid microcapsules, facilitated by the unique self-healing feature of the microcapsule.

After a single vaccination, the deposition and degradation of microcapsules at the local injection site lead to the recruitment of activated antigen-presenting cells and sustained release of both cargos.

"With the synergism of these two aspects, we observed a significant improvement in specific Cytotoxic T Lymphocyte (CTL) activation," said Prof. WEI Wei from IPE.

The researchers also verified the availability of the novel vaccine using various epitope peptides in different models, such as murine leukemia, humanized cell line-derived leukemia xenograft (CDX), and patient-derived leukemia xenograft (PDX) models.

The microcapsule-based formulation demonstrated its superior performance over that of the ISA adjuvant (commercialized adjuvant) in all leukemia therapeutic models, showing the promise of the microcapsule-based vaccine for use against various leukemia antigens in clinic.

"With the advantages of FDA-approved polylactic acid material, convenience in preparing the vaccine formulation, diversity of vaccine components, and excellent therapeutic effect, the microcapsule-based vaccine exhibits great potential for clinical translation," said Prof. MA Guanghui from IPE.

There are several types of leukemia, which are divided based mainly on whether the leukemia is acute or chronic, and whether it starts in myeloid cells or lymphoid cells. Different types of leukemia have different treatment options and outlooks, says the American Cancer Society (ACS). 

Most childhood leukemias are acute. These leukemias can progress quickly, and typically need to be treated right away. The main types of acute leukemia are:

• Acute Lymphocytic Leukemia (ALL): About 3 out of 4 childhood leukemias are ALL. These leukemias start in early forms of white blood cells called lymphocytes.
• Acute Myeloid Leukemia (AML): This type of leukemia, also called acute myelogenous leukemia, acute myelocytic leukemia, or acute non-lymphocytic leukemia, accounts for most of the remaining cases of childhood leukemia. AML starts from the myeloid cells that normally form white blood cells (other than lymphocytes), red blood cells, or platelets.
• Rarely, acute leukemias can have features of both ALL and AML. These are called mixed lineage leukemia, acute undifferentiated leukemias, or mixed phenotype acute leukemias. In children, they are generally treated like ALL and usually respond to treatment like ALL, stated the ACS.

Vax-Before-Cancer publishes oncology vaccine development news.