A Study of LY4050784 in Participants With Advanced or Metastatic Solid Tumors

Inclusion Criteria:

* Have one of the following locally advanced or metastatic solid tumor malignancy with SMARCA4 (BRG1) alteration:

  * Phase 1a dose escalation: Presence of any alteration in SMARCA4 (BRG1)
  * Phase 1b expansion: Part A: Non-small Cell Lung Cancer (NSCLC) that is locally advanced and not suitable for definitive locoregional therapy, or metastatic with presence of a known or likely loss of function alteration in SMARCA4 (BRG1) or loss of protein expression.
  * Phase 1b expansion: Part B: Any tumor type (other than NSCLC) that has the presence of a known or likely loss of function alteration in SMARCA4 (BRG1) or loss of protein expression.
  * Phase 1b expansion: Part C: Non-small Cell Lung Cancer (NSCLC) that is locally advanced and not suitable for definitive locoregional therapy, or metastatic with presence of a known or likely loss of function alteration in SMARCA4 (BRG1) or loss of protein expression.
* Prior Systemic Therapy Criteria:

  * Phase 1a dose escalation and Phase 1b (Part B): Participants who received all standard therapies for which the individual was deemed to be an appropriate candidate by the treating Investigator; or the individual is refusing the remaining most appropriate standard of care treatment; or there is no standard therapy available for the disease.
  * Phase 1b expansion (Part A): Participants must have received at least one line of therapy for advanced or metastatic disease.
  * Phase 1b expansion (Part C): Participants may be treatment naïve or have received therapy for advanced or metastatic disease
* Measurability of disease

  * Phase 1a dose escalation (excluding backfill): measurable or non-measurable disease as defined by Response Evaluation Criteria in Solid Tumors v1.1 (RECIST v1.1)
  * Phase 1a backfill and Phase 1b expansion: Measurable disease required as defined by RECIST v1.1
* Have an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1

Exclusion Criteria:

* Participants with known or likely loss of function alteration of SMARCA2 (BRM) or malignancy with known association with SMARCA2 (BRM) alterations
* Prior exposure to SMARCA2 (BRM) inhibitor(s) and/or degrader(s) (prior exposure may be permitted for dose escalation)
* Participants with known or suspected history of untreated or uncontrolled central nervous system (CNS) involvement
* Participants with history of increased risk of prolonged QT or significant arrythmia
* Significant cardiovascular disease
* Participants with active and/or treated for an additional primary malignancy within 2 years prior to enrolment
* Participants who are pregnant, breastfeeding or plan to breastfeed or expecting to conceive or father children during study or within 6 months after the last dose of study intervention
* Participants with history of active autoimmune diseases, history of allogenic stem cell/organ transplant or compromised immune system within past 2 years (Part C only)