Eligible for taxane monotherapy (i.e., absence of rapid clinical progression, life-threatening visceral metastases, or the need for rapid symptom and/or disease control) Visceral crisis or lymphangitic spread\r\n* NOTE: Visceral crisis is not the mere presence of visceral metastases, but implies severe organ dysfunction as assessed by symptoms and signs, laboratory studies, and rapid progression of disease EXCLUSION CRITERIA FOR SECOND-LINE THERAPY: Life-threatening visceral disease or other severe concurrent disease EXCLUSION CRITERIA FOR THIRD-LINE THERAPY: Life-threatening visceral disease or other severe concurrent disease Visceral crisis or impending visceral crisis at time of screening Subjects with bulky visceral disease defined as > 4 cm Symptomatic or rapid visceral progression Patients with active visceral, central nervous system, or any bone metastases melanoma (stage IVM1b or IVM1c) Life-threatening visceral disease or other severe concurrent disease Evidence of visceral metastasis to the liver. have impending visceral crisis that requires chemotherapy; Patients who have any liver metastases or visceral metastasis of ? 3 cm, plus evidence of progression meeting irRC 1.0 within 1 month before the first OBP-301 administration. Patients who have noncanonical DNA repair defects and extensive visceral disease or symptomatic bone disease requiring urgent tumor response Identified as having visceral crisis, lymphangitic spread, or leptomeningeal carcinomatosis; visceral crisis is not the mere presence of visceral metastases but implies severe organ dysfunction as assessed by symptoms and signs, laboratory studies, and rapid progression of the disease Requires urgent treatment with cytotoxic chemotherapy or other therapy is indicated (e.g., symptomatic visceral metastases) Patients with parahepatic extension of disease with direct non-liver visceral involvement No visceral crisis: Visceral crisis is moderate-to severe organ dysfunction as assessed by symptoms and signs, laboratory studies, and rapid progression of disease Development of visceral crisis since pre-registration.\r\n* NOTE: Visceral crisis is moderate-to-severe organ dysfunction as assessed by symptoms and signs, laboratory studies, and rapid progression of disease. Patients with definite liver metastasis > 1 cm or signs of visceral crisis or impending visceral crisis at the clinical discretion of the treating physician Subjects with retroperitoneal and visceral sarcoma Visceral crisis or rapidly progressive disease for which chemotherapy would be indicated Symptomatic visceral KS (except for non-ulcerating disease restricted to the oral cavity) Life-threatening visceral disease or other severe concurrent disease Symptomatic liver or visceral organ metastasis Life-threatening visceral disease or other severe concurrent disease Evidence of liver metastases or visceral disease Life-threatening visceral disease or other severe concurrent disease Life-threatening, visceral metastases Visceral metastases (e.g. lung, liver, brain, kidney, spleen) Patients must be classified as having intermediate or poor-risk germ cell tumor, as follows:\r\n* Intermediate-risk (modified*)\r\n** Testis or retroperitoneal primary non-seminomatous germ cell tumors (NSGCT) with lymph node and/or lung metastasis but without non-pulmonary visceral metastasis AND any of the following pretreatment serum tumor marker (STM) values:\r\n*** Lactate dehydrogenase (LDH) from 3 to < 10 x upper limit of normal (ULN) (*this differs from the original International Germ Cell Cancer Collaborative Group [IGCCCG] criteria which includes patients with LDH from 1.5 to 10 x ULN)\r\n*** Serum human chorionic gonadotrophin (HCG) from 5,000 to < 50,000 MIU/mL\r\n*** Serum alpha-fetoprotein (AFP) from 1,000 to < 10,000 ng/mL\r\n** Seminoma histology regardless the primary site or serum tumor markers with any non-pulmonary visceral metastasis (liver, bone, brain, etc)\r\n* Poor-risk (any of the following):\r\n** Testis or retroperitoneal NSGCT primary with non-pulmonary visceral metastasis (liver, bone, brain, etc) regardless the STM values\r\n** Mediastinal NSGCT primary site of disease regardless the presence/absence of visceral metastasis or STM values\r\n** Testis or retroperitoneal NSGCT primary without non-pulmonary visceral metastasis but with poor-risk STM values:\r\n*** LDH >= 10 x ULN\r\n*** HCG >= 50,000 MIU/mL\r\n*** AFP >= 10,000 ng/mL Visceral metastasis (excluding liver metastases) and/or lymphadenopathy Presence of skeletal, and/or soft-tissue/visceral/nodal metastasis have visceral crisis No current evidence of visceral crisis or lymphangitic spread No visceral crisis, lymphangitic spread or known brain metastases: visceral crisis is not the mere presence of visceral metastases, but implies severe organ dysfunction as assessed by symptoms and signs, laboratory studies, and rapid progression of disease Patients with immediately life-threatening visceral disease, for whom chemotherapy is the preferred treatment option. Visceral (ie, liver or lung) metastases as only sites of metastases Contraindications to angiography and selective visceral catheterization Presence of unstable systemic disease (e.g., visceral crisis or rapid progression) in the judgment of the investigator Have visceral crisis, lymphangitic spread, or leptomeningeal carcinomatosis Patients with extensive advanced/metastatic, symptomatic visceral disease, or known uncontrolled or symptomatic CNS metastases Pending visceral crisis, in the opinion of the treating investigator Visceral (eg, lung, liver) metastatic disease. Adenopathy is allowed; Has rapid progression of visceral disease and, thus is a candidate for docetaxel; this determination will be at the discretion of the treating physician A visceral metastasis greater than 8 cm A visceral metastasis that due to its location cannot be safely treated with SABR Have visceral crisis, lymphangitic spread, or leptomeningeal carcinomatosis visceral crisis is not the mere presence of visceral metastases but implies severe organ dysfunction as assessed by symptoms and signs, laboratory studies, and rapid progression of the disease History of visceral metastasis, or presence of visceral metastasis detected by screening imaging examinations History of visceral metastasis, or visceral metastases History of visceral metastasis, or visceral metastases COHORT B: Visceral metastatic disease Patients experiencing a visceral crisis including severe organ dysfunction as assessed by > grade (Gr) 2 symptomatic toxicities, laboratory studies, and/or rapid progression of disease originating from visceral metastasis Symptomatic liver or visceral organ metastasis Contraindications to angiography and selective visceral arterial catheterization Patients with rapidly progressive or extensive symptomatic visceral metastatic disease Pending visceral crisis, in the opinion of the treating investigator Life-threatening visceral disease or other severe concurrent disease Life-threatening visceral disease or other severe concurrent disease Patients who require or may be expected to require urgent treatment with docetaxel during the study (e.g., patients with visceral metastases). Presence of >= 1 metastatic site (nodal, visceral) that is amenable to core biopsy Contraindications to angiography or selective visceral catheterization Life-threatening visceral disease or other severe concurrent disease Patients with visceral disease are ineligible Patients in whom urgent treatment with docetaxel is indicated, per clinician discretion; this includes, but is not limited to patients with symptomatic visceral metastatic disease Patients with paraspinal extension of disease with visceral involvement Presence or history of visceral melanoma metastasis Eligible for taxane monotherapy, as per local investigator assessment (e.g., absence of rapid clinical progression, life-threatening visceral metastases, or the need for rapid symptom and/or disease control which may require combination chemotherapy) Life-threatening, visceral metastases Cohort A: Patients must have at least one measurable visceral lesion (per RECIST 1.1); a visceral lesion is any solid organ except for skin, lymph node, and musculoskeletal tissue; at least one of these visceral lesions must be measurable per RECIST 1.1 Cohort B: Patients must not have any visceral lesions Patients with immediately life-threatening visceral disease for whom chemotherapy is preferred treatment option. Patients with metastatic castration resistant prostate carcinoma with skeletal, visceral and/or nodal involvement AIM 3: Patients with either cutaneous, visceral or brain melanoma metastases Visceral (e.g. lung, liver) metastases