Inclusion Criteria in the pretreatment phase:  Patients must have histologically or cytologically proven metastatic or unresectable solid tumors. The disease must have progressed to at least one standard therapy (including at least one prior line with ICB for the group of patients with tumors where ICB is approved), or the patient is unable/unwilling to receive standard therapy or no standard therapy exists for a particular disease.  Patients must have at least one adequate lesion (primary tumor or metastasis) for resection or biopsy for TIL generation with minimal morbidity (preferentially using imaging-guided minimally invasive procedures).  Note: If this lesion was previously irradiated, the lesion must have demonstrated progression prior to resection/biopsy.  Patient must be at least 18 years old at the tissue procurement visit. Patient must understand and voluntarily sign an informed consent document before any study-related assessments/procedures being conducted. Patient must be able and willing to comply to the study visit schedule and protocol requirements. Patients must have a clinical performance of Eastern Cooperative Oncology Group 0 or 1. Patients are considered medically fit enough by investigator to undergo all study procedures and interventions. Patients with documented left ventricular ejection fraction (LVEF) of ≥45%. Patients with documented forced expiratory volume at one second (FEV1), forced vital capacity (FVC) and diffusing capacity of lung for carbon monoxide (DLCO) ≥50% tested by a pulmonary function test. Patients must be seronegative for HIV antibody (patients who are HIV seropositive may be less responsive and more susceptible to toxicities related to this experimental treatment since they may have a decreased immune competence). Patients must be seronegative for active hepatitis B (defined as having a negative hepatitis B surface antigen [HBsAg] test), and seronegative for hepatitis C (HCV) antibody. Patients with a history of hepatitis B virus (HBV) infection and having a negative HBsAg test and a positive antibody to hepatitis B surface antigen (HBsAg) are eligible. Patients with the hepatitis C antibody test positive are eligible only if tested for the presence of antigen by RT-PCR and be HCV RNA negative. Life expectancy ≥6 months. Patients who are of childbearing potential (postmenarcheal who has not reached a postmenopausal state and has not undergone surgical sterilization) or have partners of childbearing potential must agree to use a highly effective method of contraception during the study and for at least 6 months after the last dose of IL-2.  Inclusion Criteria in the treatment phase:  The disease must have progressed to the last standard therapy, including at least one prior line with ICB for the group of patients with tumors where ICB is approved, and no subsequent approved therapy is available, or the patients are unable/unwilling to receive standard therapy, or no standard therapy exists for a particular disease.  Patients must have a remaining measurable disease as defined by RECIST v. 1.1 criteria following tumor resection/biopsy for NEXTGEN-TIL manufacturing.  Note: Lesions previously irradiated should not be selected as target lesions unless there has been demonstrated progression in those lesions.  Patients must understand and voluntarily sign an informed consent document before any study-related assessments/procedures being conducted. Patients must be able and willing to comply with the study visit schedule and protocol requirements. Patients must have a clinical performance of Eastern Cooperative Oncology Group (ECOG) 0 or 1.  Patients are considered medically fit enough to undergo all study procedures and interventions and adequate hematological, renal and hepatic functions defined by:  Haemoglobin ≥9.0 g/dL. An absolute neutrophil count ≥1000/mm3 without the support of filgrastim. Platelets ≥ 100 x10⁹ /mm3. PT and aPTT ≤1.5 x upper limit of normal (ULN, unless receiving therapeutic anticoagulation). Subjects receiving therapeutic anticoagulation (such as low-molecularweight heparin or warfarin) should be on a stable dose. AST or ALT ≤3 x ULN. Patients with liver metastases must have AST and ALT ≤5.0 x ULN. Total bilirubin <2 mg/dL. Patients with Gilbert's Syndrome must have a total bilirubin ≤3.0 mg/dL. Serum creatinine <1.5 mg/dL or measured creatinine clearance ≥50 ml/min calculated using the Cockcroft-Gault glomerular filtration rate estimation: (140 - age) × (weight in kg) × (0.85 if female)/72 × (serum creatinine in mg/dL). Patients must be seronegative for HIV antibody. Patients must be seronegative for active hepatitis B (defined as having a negative hepatitis B surface antigen [HBsAg] test), and seronegative for hepatitis C antibody. Patients with a history of hepatitis B virus (HBV) infection and having a negative HBsAg test and a positive antibody to hepatitis B surface antigen (HBsAg) are eligible. Patients with the hepatitis C antibody test positive are eligible only if tested for the presence of antigen by RT-PCR and be HCV RNA negative. Life expectancy ≥3 months. Patients who are of childbearing potential (postmenarcheal who has not reached a postmenopausal state and has not undergone surgical sterilization) or have partners of childbearing potential must agree to use a highly effective method of contraception during the study and for at least 6 months after the last dose of IL-2.  Female participants: a female participant is eligible to participate if she is not pregnant, not breastfeeding, and at least one of the following conditions applies:  Women of non-childbearing potential (WONCBP). Women of childbearing potential (WOCBP), who:  i. Agree to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods that result in a failure rate of <1% per year from screening until 6 months after the infusion of the NEXTGEN-TIL product. Examples of contraceptive methods with a failure rate of <1% per year include bilateral tubal occlusion, male sterilization, and copper intrauterine devices.  ii. Have a negative pregnancy test (blood) within one week before the first study treatment administration (applicable to premenopausal women and women ≤2 years after the start of menopause (menopause is defined as amenorrhea for <2 years).  Male Participants: during the treatment period and for at least 2 months after the last dose of study treatment, agreement to:  Remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures such as a condom or a contraceptive method that result in a failure rate of <1% per year, with partners who are WOCBP. Refrain from donating sperm during the study. Inform if his partner gets pregnant during this time.  Any toxicity related to prior systemic therapy must have recovered to grade 1 or less according to NCI-CTCAE v5.0 at least 4 weeks before treatment enrollment, except for alopecia, vitiligo, or endocrinopathy managed with replacement therapy, and Grade ≤2 peripheral neuropathy.  Note: Other Grade 2 AEs that are deemed clinically insignificant by treating physician and in consultation with Medical Monitor are permitted.  Patients may have undergone minor surgical procedures within the past 3 weeks, as long as all toxicities have recovered to grade 1 or less.  Exclusion Criteria (any phase):  Patients with symptomatic and/or untreated brain metastases. Note: Patients with definitively-treated brain metastases will be considered for enrollment after discussion with Medical Monitor; if, prior to the start of NMA-LD the patient is clinically stable for ≥3 months, there are no new brain lesions via magnetic resonance imaging (MRI) post-treatment, and the patient does not require corticosteroid treatment >10 mg prednisone or equivalent per day. Patients with leptomeningeal carcinomatosis. Patients with an active concurrent or history within the past 3 years of invasive malignancy, except for non-melanoma skin cancer, cervical and bladder carcinoma in situ, good prognosis ductal carcinoma in situ of the breast, or prostate carcinoma that is in remission under androgen deprivation therapy for > 2 years. Other exceptions may apply and require discussion between the Investigator and the Medical Monitor. Patients with an active systemic infection requiring anti-infective treatment within 14 days before preparative lymphodepleting therapy. Patients with active hepatitis B or hepatitis C. Patients with active autoimmune disease requiring immunosuppressive treatments. Patients with a history of organ or bone marrow transplantation. Patients with any form of primary immunodeficiency (such as Severe Combined Immunodeficiency Disease and AIDS).  Patients requiring regular treatment with steroids at a dose higher than prednisone 10 mg/day (or equivalent).  Note: use of inhaled, topical steroids and use of systemic physiologic corticosteroid replacement therapy are permitted.  Patients with current or history within the last 6 months, as determined by the Investigator, of clinically significant, progressive, and/or uncontrolled renal, hepatic, hematological, endocrine, pulmonary, cardiac, gastroenterological or neurological disease. Patients with a history of coronary revascularization or ischemic symptoms. History of idiopathic pulmonary fibrosis or evidence of active pneumonitis (any origin) Patients with allergies to any of the compounds included in any of the treatment products. Patients with contraindications for cyclophosphamide, fludarabine and IL-2 at per protocol doses. Patients who have received any approved anti-cancer cytotoxic, anti-angiogenic and ICB therapy including radiotherapy within 4 weeks before preparative lymphodepleting therapy. Exception: palliative radiotherapy for bone metastasis >2 weeks before preparative lymphodepleting therapy, denosumab, bisphosphonates, androgen deprivation therapy for prostate cancer and hormonal therapy for breast cancer. Patients who have received any non-cytotoxic drug and molecular targeted therapy within 4 weeks before preparative lymphodepleting therapy (or within five half-lives of the investigational product, whichever is shorter). Patients who have received any investigational agent within 4 weeks before preparative lymphodepleting therapy (or within five half-lives of the investigational product, whichever is shorter). Patients who have received a live, attenuated vaccination within the 4 weeks before lymphodepleting therapy. Patients who have undergone major surgery in the previous 3 weeks before lymphodepleting therapy. Patients who have previously received any investigational cell or gene therapies. Women of childbearing potential who are pregnant or breastfeeding. Presence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial.