The purification procedures for the two recombinant products were similar, in that both processes used an anion exchange resin followed by the hydroxyapatite column purification steps. However, the previous process used Amersham Pharmacia Biotech's Source 30Q resin, and linear gradients were used to elute the product. In the new process the Q-Sepharose Fast Flow resin was used, and step-wise elutions were used for ease in scale-up and manufacturing. The process described above makes a consistent product at acceptable yields for the current stage of development. IDRI is producing nearly 200,000 doses per lot of vaccine based on the highest dose level currently envisioned. This level is satisfactory for the amounts needed to conduct current clinical trials, but scale-up of the process to the 300-liter scale is already ongoing. Assuming no loss in unit production, this scale would deliver 2,000,000 doses per lot and could enable large-scale clinical trials of the vaccine even without further process improvements.

An additional encouraging fact is the stability of the lyophilized protein. When performing trials or vaccinations in field settings where a cold chain cannot be guaranteed, stability of the product is crucial to successful deployment of the trial and the final product. This lyophilized vaccine product has been shown to be stable for more than three years.

IDRI has developed a process to manufacture a new recombinant protein product for the treatment and prophylaxis of leishmaniasis. This candidate vaccine consisting of Leish-110f formulated in MPL-SE will be tested in a spectrum of diseases caused by the various Leishmania species. A robust, scalable procedure will allow rapid progress in bringing this vaccine to patients and will be a step in the fight against leishmaniasis.

References

1. World Health Organization. The leishmaniases and leishmania/HIV: Co-infections (Fact Sheet No 116). Geneva; 2000.

2. Desjeux P. Leishmaniasis. Nat Rev Microbiol. 2004;2:692.

3. Bryceson A. Visceral leishmaniasis in India. Lancet. 2000;356:1933.

4. Murray HW. Clinical and experimental advances in treatment of visceral leishmaniasis. Antimicrob Agents Chemother. 2001;45:2185–97.

5. De Luca PM, et al. Evaluation of the stability and immunogenicity of autoclaved and nonautoclaved preparations of a vaccine against American tegumentary leishmaniasis. Vaccine. 1999;17:1179–85.

6. Genaro O, de Toledo VP, da Costa CA, Hermeto MV, Afonso LC, Mayrink W. Vaccine for prophylaxis and immunotherapy, Brazil. Clinics in Dermatology. 1996;14:503–12.

7. Machado-Pinto J, et al. Immunochemotherapy for cutaneous leishmaniasis: a controlled trial using killed Leishmania (Leishmania) amazonensis vaccine plus antimonial. Int J Dermatol. 2002;41:73–8.

8. Mayrink W, et al. Immunotherapy as a treatment of American cutaneous leishmaniasis: preliminary studies in Brazil. Parassitologia. 1992;34:159–65.

9. Barbosa AJ, Raso P, Genaro O, da Costa CA, Mayrink W. On leishmanial antigen detection in tissue sections of Montenegro's reaction [letter]. Revista do Instituto de Medicina Tropical de Sao Paulo. 1994;36:95–6.

10. Mayrink W, et al. Phase 1 and 2 open clinical trials of a vaccine against Leishmania chagasi infections in dogs. Memorias Do Instituto Oswaldo Cruz. 1996;91:695–7.

11. Mora AM, Mayrink W, Costa RT, Costa CA, Genaro O, Nascimento E. Protection of C57BL/10 mice by vaccination with association of purified proteins from Leishmania (Leishmania) amazonensis. Revista do Instituto de Medicina Tropical de Sao Paulo. 1999;41:243–8.