a) activating peripheral blood mononuclear cells (PBMCs), total leukocytes or specific sub-populations of PBMCs, obtained from a biological sample selected from the group consisting of blood and a blood cellular derivative of the patient, either: i) though incubation with a lymphocyte activation compound selected from the group consisting of agonistic antibodies anti-CD3 (T-cell Receptor (TCR)) and anti-CD28, ionomycin and PMA (phorbol myristate acetate), a lectin, a superantigen, and a Lipopolysaccharide (LPS); or ii) through a Mix Lymphocyte Reaction, to obtain activated PBMCs;

b) obtaining a hydrogel comprising the activated PBMCs, total leukocytes or specific sub-populations of PBMCs, embedded within the hydrogel by incorporating the activated cells into a hydrogel, wherein;

c) contacting the hydrogel of step b) with one or more immune-modulator drugs;

d) adding a solution comprising a compound capable of providing an absorbance, fluorescence or luminescence signal, thereby defining an inhibitory zone around a site of contact of an immunosuppressant drug with the hydrogel; and

e) obtaining a quantification of the immune-modulator drug gradient formed, wherein the quantification is obtained by image acquisition or quantification of the absorbance, fluorescence or luminescence signal,

wherein:

the hydrogel is formed through non-covalent crosslinking of polymer chains, wherein the total polymeric fraction represents less than 5% (5 gr/100 ml of hydrogel);

the hydrogel composition generates a non-toxic environment able to sustain cell proliferation having adequate nutritional composition and stiffness, and absent of unspecific induction of PBMCs activation; and

the total polymeric fraction of the hydrogel consists of collagen, wherein the collagen content is present at below or equal to 0.3% (gr/100 ml of hydrogel).