Monoclonal antibodies against infectious microbes: so long and too little!

Monoclonal antibodies (mAbs) as alternatives or more often as complementary to the conventional antimicrobials are being developed for the management of infectious conditions for the past two decades. These pharmacotherapeutic strategies are inevitable as the burden of antimicrobial resistance is far-reaching in recent times. MAbs are part of the targeted pharmacotherapy armamentarium with high degree of specificity - hence, exert comparatively superior efficacy and tolerability than the conventional polyclonal antisera. So far, only five mAbs have been approved for the management of infectious states - since, the marketing authorization (1998) given to palivizumab (Synagis(R)) for the prophylaxis of lower respiratory tract disease caused by respiratory syncytial virus in pediatric patients. Ibalizumab-uiyk (Trogarzo) used for the management of multidrug resistant HIV-1 infection not yielding to at least 10 antiretroviral drugs previously was approved recently. Among the three antibacterial mAbs, raxibacumab (ABthrax(R)/ Anthrin(R)) and obiltoxaximab (Anthim(R)) are indicated for the treatment and prophylaxis of inhalation anthrax due to Bacillus anthracis; bezlotoxumab (Zinplava(R)) is used to reduce the recurrence of Clostridium difficile infection. There are also around 30 and 15 mAbs in different phases of development for viral and bacterial conditions. As alternatives to the traditional antivirals and antibacterials, the antimicrobial mAbs are the need of the hour. These mAbs are more relevant in the management of conditions like emerging viral outbreaks wherein there is a lack of prophylactic vaccines. The current cutting-edge engineering technologies revolutionizing the production of mAbs include phage-displayed antibody libraries, cloning from single-memory B cells or single-antibody-secreting plasma B cells, proteomics-directed cloning of mAbs from serum clubbed with high-throughput sequencing techniques. Yet, the cost of manufacture continues to be the main limiting factor.