• Male or female age ≥ 18 years at the time of informed consent.

• Be capable, willing, and able to provide written informed consent.

• Be willing to comply with clinical trial instructions and requirements, including tumor biopsies (if feasible and required per protocol).

• Patients must have a locally advanced or metastatic cancer, a malignant solid tumor that has progressed on at least one line of systemic therapy or for which no standard treatment is available, the participant is intolerant to available treatment, or the participant declined standard of care systemic therapy.

• In the dose escalation phase study patients must have a histologically or cytologically confirmed malignant solid tumor that has progressed on at least one prior standard of care systemic therapy, where available, or declined standard of care systemic therapy.

• In the dose expansion phase, must have a histologically or cytologically confirmed antiPD1/PD-L1 undifferentiated pleomorphic sarcoma or myxofibrosarcoma, angiosarcoma, or bone sarcoma or merkel cell carcinoma. Patients with UPS/MFS, angiosarcoma and MCC must have progressed on or be refractory to anti-PD-1/anti-PD-L1 therapy.

• In the dose escalation phase an upper bound weight limit restriction will be used for dose levels 5 and 6. Hence, patients must weight ≤90kg and ≤70kg in order to be eligible to enroll in dose level 5 and 6 of the dose escalation phase, respectively.

• Adequate performance status: ECOG 0 or 1/KPS 100-70%.

• Life expectancy of at least three months after the first CRD3874 infusion, according to the Investigator's opinion

• Presence of measurable disease per RECIST v1.1.Target lesion(s) must not be chosen from a previously irradiated field unless there has been radiographically and/or pathologically documented tumor progression in that lesion prior to enrollment.

• In the dose expansion phase , participants must agree to have a pretreatment tumor biopsy for research purposes. Participants in whom biopsy is technically not feasible or in whom the associated procedure would result in unacceptable risk, in the opinion of the Investigator, or patients who do not wish to have a biopsy, archival tissue (most recently procured sample where tissue is available) may be used instead, if available.

• In the dose expansion phase , participants must agree to on-treatment tumor biopsy for research purposes. Participants in whom biopsy is technically not feasible or in whom would result in unacceptable risk, in the opinion of the Investigator, or patients who do not wish to have a biopsy- may be exempted from the biopsy requirement with discussion with the Principal Investigator .

• Female subject of childbearing potential (defined as a sexually mature female who has not undergone a hysterectomy or bilateral oophorectomy or who has not been naturally postmenopausal for at least 24 consecutive months) should have a negative serum pregnancy testing at screening visit and within 72 hours prior to the first dose of study medication.

• Adequate organ function determined within 14 days of treatment initiation, defined as follows:

‣ Hemoglobin ≥ 9.0 g/dL

⁃ Absolute neutrophil count ≥ 1,000/mm\^3 (1.0 x 10\^9/L)

⁃ Platelet count ≥ 100,000/mm3 (100 x 10\^9 /L)

⁃ Serum bilirubin ≤ 1.2x upper limit of normal (ULN) OR direct bilirubin ≤ ULN for participants with total bilirubin level \> 1.2x ULN

⁃ Aspartate aminotransferase (AST) ≤ 2.5x ULN OR ≤ 5x ULN for participants with liver metastases

⁃ Alanine aminotransferase (ALT) ≤ 2.5x ULN OR ≤ 5x ULN for participants with liver metastases

⁃ Albumin ≥ 2.5mg/dL.

⁃ Calculated creatinine clearance (CrCl) ≥ 60 mL/min by Cockcroft-Gault formula or CKD-EPI 2021

⁃ International Normalized Ratio (INR) or prothrombin time (PT) ≤1.5x ULN unless participant is receiving anticoagulant therapy as long as PT or partial thromboplastin time (PTT) is within therapeutic range of intended use of anticoagulants.

⁃ Activated partial thromboplastin time (aPTT) ≤ 1.5x ULN unless participant is receiving anticoagulant therapy as long as PT and PTT is within therapeutic range of intended use of anticoagulants

⁃ Left ventricular ejection fraction (LVEF) \> 50%, as measured by echocardiogram (2D-ECHO) or multi-gated acquisition scan (MUGA)