The multi-specific VH-based Humabody CB213 co-targets PD1 and LAG3 on T cells to promote anti-tumour activity.

BACKGROUND: Improving cancer immunotherapy long-term clinical benefit is a major priority. It has become apparent that multiple axes of immune suppression restrain the capacity of T cells to provide anti-tumour activity including signalling through PD1/PD-L1 and LAG3/MHC-II. METHODS: CB213 has been developed as a fully human PD1/LAG3 co-targeting multi-specific Humabody composed of linked VH domains that avidly bind and block PD1 and LAG3 on dual-positive T cells. We present the preclinical primary pharmacology of CB213: biochemistry, cell-based function vs. immune-suppressive targets, induction of T cell proliferation ex vivo using blood obtained from NSCLC patients, and syngeneic mouse model anti-tumour activity. CB213 pharmacokinetics was assessed in cynomolgus macaques. RESULTS: CB213 shows picomolar avidity when simultaneously engaging PD1 and LAG3. Assessing LAG3/MHC-II or PD1/PD-L1 suppression individually, CB213 preferentially counters the LAG3 axis. CB213 showed superior activity vs. αPD1 antibody to induce ex vivo NSCLC patient T cell proliferation and to suppress tumour growth in a syngeneic mouse tumour model, for which both experimental systems possess PD1 and LAG3 suppressive components. Non-human primate PK of CB213 suggests weekly clinical administration. CONCLUSIONS: CB213 is poised to enter clinical development and, through intercepting both PD1 and LAG3 resistance mechanisms, may benefit patients with tumours escaping front-line immunological control.

Potent and broad neutralization of HIV-1 by a llama antibody elicited by immunization.

Llamas (Lama glama) naturally produce heavy chain-only antibodies (Abs) in addition to conventional Abs. The variable regions (VHH) in these heavy chain-only Abs demonstrate comparable affinity and specificity for antigens to conventional immunoglobulins despite their much smaller size. To date, immunizations in humans and animal models have yielded only Abs with limited ability to neutralize HIV-1. In this study, a VHH phagemid library generated from a llama that was multiply immunized with recombinant trimeric HIV-1 envelope proteins (Envs) was screened directly for HIV-1 neutralization. One VHH, L8CJ3 (J3), neutralized 96 of 100 tested HIV-1 strains, encompassing subtypes A, B, C, D, BC, AE, AG, AC, ACD, CD, and G. J3 also potently neutralized chimeric simian-HIV strains with HIV subtypes B and C Env. The sequence of J3 is highly divergent from previous anti-HIV-1 VHH and its own germline sequence. J3 achieves broad and potent neutralization of HIV-1 via interaction with the CD4-binding site of HIV-1 Env. This study may represent a new benchmark for immunogens to be included in B cell-based vaccines and supports the development of VHH as anti-HIV-1 microbicides.

Molecular diagnosis and analysis of Chikungunya virus.

BACKGROUND: In March 2005 a Chikungunya fever outbreak began on the islands of the Indian Ocean. The number of cases of this disease dramatically rose amongst these islands before affecting over a million people in India. Travellers to these regions have returned to the UK with the disease leading to a greater than 15-fold increase in the annual number of Chikungunya virus (CHIKV) sero-positive samples in 2006. OBJECTIVES: A real-time RT-PCR test was developed for CHIKV and designed to detect currently circulating strains of virus as well as other genotypes. Its sensitivity was compared with an existing standard RT-PCR assay and a previously published real-time assay. STUDY DESIGN: A real-time RT-PCR assay was optimised and evaluated using a panel of 55 clinical serum samples and a synthetic RNA transcript as a positive control. Nucleotide sequencing of part of the E1 gene of CHIKV was used to investigate the relatedness of the samples. RESULTS: The real-time RT-PCR was 10-fold more sensitive than a conventional block-based RT-PCR and could detect as low as 20 copies of RNA transcript. The assay also had 10-fold improved sensitivity in detecting the outbreak strain of virus when compared to another published TaqMan assay. Analysis of sequences from patients that had travelled to India, Mauritius or the Seychelles showed high similarity with published sequences from the Indian Ocean island of Réunion. CONCLUSIONS: A sensitive and rapid real-time RT-PCR assay has been developed for CHIKV and tested against current isolates.