Targeted oncotherapeutics offer progress in improved treatment for individuals diagnosed with cancer; however, patient-developed resistance, both to conventional chemotherapies and to single agents, remains a major hurdle. A current approach to combating drug resistance and risk of cancer recurrence is to find combinations of drugs that effectively target multiple functional pathways, increasing the prospect of providing more durable cancer cell kill. However, combination drug treatment introduces a daunting number of options as the plethora of small molecule and antibody immunotherapy compounds available continues to grow, presenting major challenges in identifying candidate combination pairs of suitable, high effect. Here we describe a miniaturized single cell imaging approach for evaluating ex vivo combination drug responses in primary patient cells which uses minimal sample requirement, enabling screening of up to 50 drug conditions per one million primary cells. This approach also employs the capability to perform digitized molecular counting to quantify surface and intracellular protein targets within single cells that may often be present at low levels in single cells (e.g., phosphoproteins, immune modulatory molecules induced via inflammation). This miniaturized single cell imaging approach offers new capabilities for assessing the functional/pathway status of primary patient single cells from distinct cell subpopulations and profiling the therapeutic effect of multiple protein targets to combinations of drugs, with single cell, high-content information.