Although two growth factor receptors, EGFR and HER2, are amongst the best targets for cancer treatment, no agents targeting HER3, their kinase-defective family member, have so far been approved. Because emergence of resistance of lung tumors to EGFR kinase inhibitors (EGFRi) associates with compensatory up-regulation of HER3 and several secreted forms, we anticipated that blocking HER3 would prevent resistance. As demonstrated herein, a neutralizing anti-HER3 antibody we generated can clear HER3 from the cell surface, as well as reduce HER3 cleavage by ADAM10, a surface metalloproteinase. When combined with a kinase inhibitor and an anti-EGFR antibody, the antibody completely blocked patient-derived xenograft models that acquired resistance to EGFRi. We found that the underlying mechanism involves posttranslational downregulation of HER3, suppression of MET and AXL upregulation, as well as concomitant inhibition of AKT signaling and upregulation of BIM, which mediates apoptosis. Thus, although HER3 is nearly devoid of kinase activity, it can still serve as an effective drug target in the context of acquired resistance. Because this study simulated in animals the situation of patients who develop resistance to EGFRi and remain with no obvious treatment options, the observations presented herein may warrant clinical testing.

BackgroundSOBERANA 02 is a COVID-19 conjugate vaccine candidate based on SARS-CoV-2 recombinant RBD conjugated to tetanus toxoid. SOBERANA Plus antigen is dimeric-RBD. Here we report safety, reactogenicity and immunogenicity from phase I and IIa clinical trials using two-doses SOBERANA 02 (homologous protocol) and three-doses (homologous) or heterologous (with SOBERANA Plus) protocols.MethodWe performed an open-label, monocentric, sequential and adaptive phase I for evaluating safety, reactogenicity and exploring immunogenicity of SOBERANA 02 in two formulations (15 and 25 μg) in 40 subjects, 19–59 years old. Phase IIa was open-label including 100 volunteers 19–80 years, receiving two doses of SOBERANA 02-25 μg. In both trials, half of volunteers received a third dose of SOBERANA 02, half received a heterologous dose of SOBERANA Plus-50 μg. Primary outcomes were safety and reactogenicity. The secondary outcome was vaccine immunogenicity evaluated by anti-RBD IgG ELISA, molecular neutralization test of RBD:hACE2 interaction, live-virus neutralization test and specific T-cells response.ResultsThe most frequent AE was local pain, other AEs had frequencies ≤ 5%. No serious related AEs were reported. Phase IIa confirmed the safety results in 60–80 years subjects. In phase-I SOBERANA 02-25µg elicited higher immune response than SOBERANA 02-15 µg; in consequence, the higher dose progressed to phase IIa. Phase IIa results confirmed the immunogenicity of SOBERANA 02-25 μg even in 60–80 age range. Two doses of SOBERANA02-25 μg elicited an immune response similar to that of the Cuban Convalescent Serum Panel; it was higher after both the homologous and heterologous third doses; the heterologous scheme showing a higher immunological response.ConclusionsSOBERANA 02 was safe and immunogenic in persons aged 19–80 years, eliciting neutralizing antibodies and specific T cell response. Highest immune responses were obtained in the heterologous three doses protocol. Trial registry: https://rpcec.sld.cu/trials/RPCEC00000340 and https://rpcec.sld.cu/trials/RPCEC00000347

The human epidermal growth factor receptor (HER1) and its partner HER2 are extensively described oncogenes and validated targets for cancer therapy. However, the effectiveness of monospecific therapies targeting these receptors is hampered by resistance emergence, which is frequently associated with the upregulation of other members of HER family. Combined therapies using monoclonal antibodies or tyrosine kinase inhibitors have been suggested as a promising strategy to circumvent this resistance mechanism. We propose an alternative approach based on simultaneous inactivation of HER1 and HER2 by multi-epitope blockade with specific polyclonal antibodies induced by vaccination. Elicited antibodies impaired both receptors activation and induced their degradation, which caused the inhibition of down-signaling cascades. This effect was translated into cell cycle arrest and apoptosis induction of human tumor cells. Elicited antibodies were able to reduce the viability of a panel of human tumor lines with differential expression levels of HER1 and HER2. The most significant effects were obtained in the tumor lines with lower expression levels of both receptors. These new insights would contribute to the rational design of HER receptors targeting multivalent vaccines, as an encouraging approach for the treatment of cancer patients.

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Background: Cancer immunotherapy based on direct intratumoral injection of immunomodulators has been established at the end of 19th century using Coley's toxin. Our novel therapeutic strategy is based on the intratumoral injection of optimized mixture of TLR agonists, causing strong inflammatory infiltration. Infiltrating cells (mainly phagocytes) are directed to artificially opsonized tumor cells covered by phagocytosis stimulating ligands. Materials and methods: Immunotherapy was tested using B16-F10 murine melanoma model. Inflammatory infiltration was achieved using the mixture of resiquimod, poly(I:C), and lipoteichoic acid. Artificial opsonisation of tumor cells was elicited by mannan anchored to cell membranes using a hydrophobic anchor. The course of tumor infiltration was studied using flow cytometry. Cytotoxic effect of infiltrating immune cells on opsonized tumor cells was studied in vitro. Participation of acquired immunity was elucidated on the basis of intracellular IFN-gamma production by lymphocytes. Results: Optimized cancer immunotherapy based on the synergy of TLR agonists with artificially induced tumor opsonisation resulted in complete cure of 83% of mice with advanced melanomas. Moreover, cured mice acquired resistance to retransplantation of tumor cells. Applied therapy has a strong antimetastatic effect. In the first phase of immunotherapy, granulocyte predominance was observed, followed by involvement of acquired immunity. Conclusions: Intratumoral immunotherapy initiated by innate immunity based attack followed by joining of mechanisms of acquired immunity is a promising approach for future application in clinical practice as compounds used are safe for humans.