Inclusion Criteria:
* Patients with recurrent or refractory small cell lung cancer (SCLC) confirmed by histology or cytology who have relapsed or progressed after treatment with one previous platinum-based regimen;
* Patients can provide sufficient tumor tissue (fresh or paraffin sections, etc.);
* Age 18 \~70 (including boundary), for both men and women;
* Eastern Cooperative Oncology Group (ECOG) performance status of 0-1;
* Life expectancy ≥3 months;
* At least one extracranial measurable lesion (RECIST v1.1) exists；for lesion after radiotherapy， must be confirmed that the lesion has progressed ;
* Patients in limited-stage at the initial diagnosis must undergo radical thoracic radiotherapy and the time of tumor progression is not less than 3 months from the end of radiotherapy, or radical thoracic dose radiotherapy cannot be performed for specific reasons;
* The test results of human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), hepatitis C and syphilis were negative at screening;
* Female patients or male reproductive age patients and their partners should agree to effective contraception from sighing Informed Consent Form (ICF) to 6 months after the last BHP01 infusion.
Exclusion Criteria:
* Patients with known primary Central Nervous System (CNS) tumor, or meningeal metastasis, or patients with unstable CNS metastasis (symptomatic, requiring hormonal therapy within 4 weeks before investigational treatment, or no radiographic evidence of stabilization of the lesion for more than 4 weeks);
* Received major surgical procedures （except for diagnosis） within 4 weeks before PBMCs collection, or are expected to require major surgical procedures during the study;
* Received Chinese herbal medicine or Chinese patent medicine for anti-tumor indications within 7 days before Peripheral Blood Mononuclear Cells (PBMCs) collection;
* Patients with a history of idiopathic pulmonary fibrosis, mechanical pneumonia (such as bronchiolitis obliterans), drug-induced pneumonia or idiopathic pneumonia, or evidence of active pneumonia by chest computer tomography (CT) at screening \[a history of radiation pneumonia (fibrosis) in the irradiated field may participate in this study\];
* Poorly controlled pleural effusion, pericardial effusion, or ascites requiring repeated drainage procedures (once a month or more frequently);
* Poorly controlled or symptomatic hypercalcemia (ionic calcium\> 1.5 mmol/L, calcium\> 12 mg/dL or corrected calcium\> ULN);
* Presence of active or previous autoimmune diseases or immunodeficiencies, including but not limited to myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, rheumatoid arthritis, etc.;
* Severe infection within 4 weeks before the start of PBMCs collection, including but not limited to hospitalization due to infection, bacteremia, severe pneumonia, or any active infection that may affect the patient's safety;
* Serious cardiovascular and cerebrovascular diseases (such as heart disease ≥New York Heart Association class II, myocardial infarction or cerebrovascular accident), unstable arrhythmia or unstable angina pectoris within 3 months before PBMCs collection;
* Previous treatment with DLL 3 target drugs or CAR-T or other gene-modified T cells;
* Received any other Investigational drug within 28 days prior to PBMCs collection;
* A history of mental illness;
* Incapacitated persons or persons with limited capacity;
* pregnant or lactating females; Males or females who are unwilling to use adequate contraception; Females of childbearing potential are required to undergo a pregnancy study during the screening period;
