This is a prospective interventional open-label randomized trial. The patients treated with anti-||PD-1 (programmed-death receptor type 1) or anti-PD-L1 (programmed-death ligand) antibodies in case of new acute onset interstitial changes or new seriuos respiratory system related symptoms will be recruited for this study to perform diagnostics. At the recruitment the patient will be randomized 1:1 to investigatory or control arm, the randomization will be stratified upon three criteria:||severity of suspected pneumonitis at baseline (grade 2 vs. grade 3-4)|response for oncological treatment (partial response (PR) and complete response (CR) vs. stable disease (SD) and progression disease (PD))|chronic respiratory system disorders Both groups will be treated in the same way in terms of diagnostic procedures. In case of interstitial lung diseases related to immune checkpoint inhibitor is confirmed with the severity of grade 2-4 in the modified CTCAE criteria the patient will get the treatment, accordingly to the randomization: ARM A - INVESTIGATORY GROUP the start dose will be 1-4 mg/kg of body weight of prednisone, depending on clinical condition and pneumonitis severity, the induction treatment will last for 5-7 days, in case of severe condition - no improvement after 48-72 h of initial treatment - introduction of immunosuppressive agent is recommended - cyclophosphamide, mofetil mycophenolate or infliximab. A continuation treatment with dose tapering is than recommended, starting from 60mg q 24h of prednisone for 2-4 weeks, and dropping the dose 10mg q 24 h not faster than over 14 days; the maintenance dose of prednisone 10mg q 24 h should be hold for 8 weeks and withdraw should last for 4 weeks. This arm will be treated with corticosteroid for at least 12-24 weeks.||ARM B - CONTROL GROUP the starting dose will be 1-4mg/kg of body weight of prednisone , depending on clinical condition and pneumonitis severity, the induction treatment will last 5-7 days; in case of severe condition - no improvement after 48-72 h of initial treatment - introduction of immunosuppressive agent is recommended: cyclophosphamide, mofetil mycophenolate or infliximab. A continuation treatment with dose tapering is than planned, starting from oral dose of 30-60mg q 24h of prednisone, and dose reduction of 10mg q 24 h each 1 week. This arm will be treated for 6-12 weeks.||During the treatment and after its termination the function of respiratory system, interstitial changes in radiologic examinations, anticancer response, survival time, pneumonitis relapse and glucocorticosteroid side effects will be monitored and evaluated. The observation will last up to 52 weeks.