Biological activity of LALF32-51–E7, a vaccine candidate for the treatment of anogenital lesions associated to HPV16

Cervical cancer is the second leading cause of cancer death in women. It is well established that human papillomavirus (HPV) is the cause of virtually 100% of these cancers, 70% of which are attributable to infections with HPV types 16 or 18. We developed a fusion protein comprising a cell penetrating and immunostimulatory peptide corresponding to residues 32 to 51 of the Limulus polyphemus protein (LALF32-51) linked to the HPV16 E7 antigen (LALF_32-51–E7) that is obtained from Escherichia coli. The development of new treatments as mentioned requires a robust and reproducible procedure for batch release. We used the combination of three batches of LALF_32-51-E7 with Al(OH)₃ in an experimental design to develop a biological activity test for batch release of this candidate, which uses prophylactic immunization in the TC-1 tumor mouse model. Two injections, spaced for 7 days with LALF_31-52-E7+Al(OH)₃ are sufficient for inducing a potent anti-tumor response in the TC-1 tumor model. LALF_31-52-E7 vaccine candidates in combination with Al(OH)₃, exhibited in C57BL/6 mice over 86% protection against tumor challenge and high titers of specific antibodies against LALF_31-52-E7. The results obtained across three batches of LALF_32-51–E7+Al(OH)₃ with this simple and uncomplicated assay based on prophylactic immunization in the TC-1 mouse model suggest that it would be feasible to implement it as a biological activity assay for the release of production batches of LALF_32-51–E7.