Provided toxicity is tolerable, dual combination of either PI3K or AKT inhibitors with HER3-neutralizing monoclonal antibody, or triple combination of PI3K/AKT, HER2 inhibitors and a HER3 antibody may be fruitful therapeutics for HER2+ as well as non-HER2+ cancers, as these combinations would more completely eliminate HER2-mediated HER3 activation. Here, PIK3CD is linked to cancer.