In Phase I, dose escalation will begin at the lowest dose level and will escalate to the next level when the first patient at the lowest dose level has completed the first 14 doses of treatment or at least 9 doses (70% of the planned dose) in the case of definitive discontinuation for a reason other than the presence of a serious adverse event (SAE), without presenting signs or symptoms that show limiting toxicity and that prevent further treatment. The inclusion of patients in successive dose levels will continue in an ascending manner (1 patient per dose level), under the same criteria. If signs or symptoms that prevent further treatment (TLD: dose-limiting toxicity) appear in a patient at any dose level, 2 more patients will be included at the same dose level. If no TLD events occur, the dose will be escalated to the next level, and if a TLD occurs, the next dose level to be de-escalated will be estimated based on the dose-toxicity model updated with the accumulated information. When six subjects are enrolled at the same dose level, this will be considered the Maximum Tolerable Dose (MTD). If the limiting dose for toxicity is not observed between the prescribed levels, a higher dose, estimated using the dose-toxicity model (2400 U/kg), will be considered. De-escalation may be performed to only one dose level below the specified minimum and escalation to only one dose level above the maximum. If the maximum dose level is reached without DLT events, the enrollment of six patients at the same level will be completed. The occurrence of SAEs of grade ≥4 intensity, with demonstrated causality to the non-alpha IL-2 mutein (definite, very probable, or probable causality), will be considered a DLT. Once Stage I is completed and the MTD is defined, Stage II will be performed, assigning patients to up to three cohorts based on the type of tumor diagnosed (pancreatic/triple-negative, ovarian (platinum-resistant), melanoma/clear cell renal). Patients will be assigned continuously to each cohort. Treatment in Stage I will consist of two cycles of intravenous IL-2 non-alpha mutein. In each cycle, one dose will be administered every 8 hours in no less than 15-30 minutes, up to a maximum of 14 doses (4.6 days or 110 hours). The patient will rest for 9 days and receive the same number of doses in the second cycle. In Stage II, patients will initially receive one course of treatment (two cycles) of intravenous IL-2 non-alpha mutein. Each dose will be administered over 30 minutes, one dose every 8 hours, up to a maximum of 14 doses (4.6 days or 110 hours). The interval between cycles will be 9 days. Four weeks after completing the first course of treatment, the patient will be evaluated by laboratory and imaging studies. Depending on the response (evidence of at least disease stabilization) and if no adverse events contraindicating the use of Mutein appear, the next course of treatment will be administered 4 weeks after the evaluation (2 months after the last Mutein cycle). Courses may be repeated until a full year of treatment is completed, always following the guidelines described for the second course of treatment. In Stage I, the primary endpoint will be the occurrence of serious adverse events with a proven causal relationship (definite, very probable, or probable) with the administration of the product, and the dose to be evaluated in the next stage will be determined. In Phase II, the pharmacokinetic profile of the non-alpha IL-2 mutein will be characterized in 25 patients treated with the dose selected in Phase I (1200 U/kg). All patients included, regardless of the study stage, will be evaluated for antitumor effect, overall survival, progression-free survival, duration of response, immune response, immunogenicity, and the safety of the treatment regimen. The characterization of the pharmacokinetic profile will allow for estimating bioavailability (F), volume of distribution (V), elimination constant (k), maximum concentration (Cmax), half-life (T 1/2), and plasma clearance (Cl). Sampling will be performed during the first course of treatment, after the first dose of cycle 1, and at the last dose of cycles 1 and 2, using a sparse data design in blocks of 5 patients per sample collection design, so that each patient will receive 9 samples. Objective response will be assessed 4 weeks after the completion of the last dose of the non-alpha IL-2 mutein of the second cycle (course 1). If patients receive more courses of treatment, they will also be assessed at the end of the course. If patients do not receive more than one course of treatment, they will be followed up at months 6 and 9 from inclusion, with study completion at 12 months. Laboratory tests and imaging studies will be performed at each of these evaluations. Administration of the non-alpha IL-2 mutein is expected to be safe, assuming that no more than 40% of patients will experience SAEs of grade ≥4 intensity, with a demonstrated causal relationship (definite, very probable, or probable) with the product administration, and up to 33% will experience SAEs of grade 3 severity. The objective response rate (CR and PR) will be estimated as the primary indicator of effect (during the second phase), and is expected to occur in no less than 15% of patients.