• Be at least 18 years of age and willing and able to provide a written informed consent

• Have histologically/cytologically confirmed unresectable small cell lung carcinoma (SCLC), large cell neuroendocrine lung carcinoma (LCNEC), combined SCLC, or combined LCNEC as per WHO 2021 criteria

• Subjects who have at least one prior line of standard treatment, and have progressed after or have had an insufficient response, and for whom standard treatment is intolerable, unlikely to confer significant clinical benefit, is no longer effective, or the subject declines further standard treatment

• Have available formalin-fixed, paraffin-embedded tumor specimen in a tissue block or unstained serial slides accompanied by an associated pathology report prior to enrollment. Archival or fresh biopsy tissue is required

• Presence of ≥ 1 radiologically measurable lesion per Response Evaluation Criteria In Solid Tumors (RECIST) Version 1.1

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

• Life expectancy of at least 4 months

• Have adequate organ function

• Women of childbearing potential must have a negative pregnancy test at screening using a highly sensitive serum pregnancy test (β-human chorionic gonadotropin \[β-hCG\])

• All subjects must agree to practice a highly effective method of contraception (failure rate of \<1% per year when used consistently and correctly) from the time of signing the informed consent form (ICF) to 1 year after receiving a LB2102 infusion

• Women and men must agree not to donate eggs (ova, oocytes) or sperm, respectively, until at least 1 year after receiving a LB2102 infusion