A Phase I, Open-Label Study of GSK1795091 Administered in
Combination with Immunotherapies in Participants with Advanced Solid Tumors.

1. Participant must be *18 years of at the time of signing the informed consent.
2. Histological documentation of advanced solid tumor, other than TNBC (defined per ASCO/CAP guidelines) [Hammond, 2010; Wolff, 2013].
3. Archival tumor tissue obtained at any time from the initial diagnosis to study entry. Although a fresh biopsy obtained during screening is preferred, archival tumor specimen is acceptable if it is not feasible to obtain a fresh biopsy.
Note: Participants enrolled in a PK/Pharmacodynamic Cohort must provide a fresh biopsy of a tumour lesion not previously irradiated during the screening period and must agree to provide at least one additional on-treatment biopsy.
4. Disease that has progressed after standard therapies or for which standard therapy is otherwise unsuitable (e.g., intolerance).
5. Measurable disease, i.e., presenting with at least 1 measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST version 1.1).
6. Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1.
7. Life expectancy of at least 12 weeks.
8. Adequate organ function
9. applicable for France only
10. Male or female
a. Female participants:
A female participant is eligible to participate if she is not pregnant, not breastfeeding, and at least 1 of the following conditions applies:
i. Not a woman of childbearing potential (WOCBP)
OR
ii. A WOCBP who agrees to follow the contraceptive guidance
during the treatment period and for at least 120 days after the last dose of study treatment.
11. Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the ICF and in this protocol.
Additional Inclusion Criteria for Patients in Part 2
12. Histological or cytological documentation of SCCHN (oral cavity, oropharynx, hypopharynx, or larynx) that is recurrent, locally advanced, or metastatic and is not amenable to curative treatment options, surgery or definitive chemoradiation therapy.
13. Received or ineligible for platinum-based therapy and PD-1/PD-L1 therapy.
14. Received no more than 3 prior lines of systemic therapy for metastatic disease.

1. Malignancy other than disease under study with the exception of those from which the participant has been disease-free for more than 2 years and not expected to affect the safety of the participant or the endpoints of the trial.
2. Symptomatic central nervous system (CNS) metastases or asymptomatic CNS metastases that have required steroids within 2 weeks prior to first dose of study treatment.
3. Active autoimmune disease that has required systemic disease modifying or immunosuppressive treatment within the last 2 years.
Note: Replacement therapy (e.g., thyroxine or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is permitted.
4. Concurrent medical condition requiring the use of systemic immunosuppressive treatment within 28 days before the first dose of study treatment.
5. Known human immunodeficiency virus infection.
6. Current unstable liver or biliary disease per investigator assessment defined by the presence of ascites, encephalopathy, coagulopathy, hypoalbuminaemia, oesophageal or gastric varices, persistent jaundice, or cirrhosis.
NOTE: Stable chronic liver disease (including Gilbert*s syndrome or asymptomatic gallstones) or hepatobiliary involvement of malignancy is acceptable if participant otherwise meets entry criteria.
7. Presence of Hepatitis B surface antigen (HBsAg) at screening or within 3 months prior to first dose of study treatment
8. Positive Hepatitis C test result at screening or within 3 months prior to first dose of study treatment.
NOTE: Participants with positive Hepatitis C antibody due to prior resolved disease can be enrolled, only if a confirmatory negative Hepatitis C RNA test is obtained. Participants with negative Hepatitis C antibody test are not required to also undergo Hepatitis C RNA testing
9. QTcF >450 msec or QTcF >480 msec for participants with bundle branch block
The QTcF is the QT interval corrected for heart rate according to Fridericia*s formula, machine-read or manually over-read.
10. Recent history (within the past 6 months) of acute diverticulitis, inflammatory bowel disease, intra-abdominal abscess, or gastrointestinal obstruction.
11. Recent history of allergen desensitization therapy within 4 weeks of starting study treatment.
12. History of severe hypersensitivity to mAbs.
13. History or evidence of cardiovascular (CV) risk including any of the following:
* Recent (within the past 6 months) history of serious uncontrolled cardiac arrhythmia or clinically significant ECG abnormalities including second degree (Type II) or third degree atrioventricular block.
* Cardiomyopathy, myocardial infarction, acute coronary syndromes (including unstable angina pectoris), coronary angioplasty, stenting, or bypass grafting within the past 6 months before enrollment.
* Congestive heart failure (Class II, III, or IV) as defined by the New York
Heart Association functional classification system [NYHA, 1994].
* Recent (within the past 6 months) history of symptomatic pericarditis.
14. History of idiopathic pulmonary fibrosis, pneumonitis, interstitial lung disease, or organizing pneumonia, or evidence of active, non-infectious pneumonitis. Note: post-radiation changes in the lung related to prior radiotherapy and/or asymptomatic radiation-induced pneumonitis not requiring treatment may be permitted if agreed by the investigator and Sponsor.
15. Recent history (within 6 months) of uncontrolled symptomatic ascites or pleural effusions.
16. Any serious and/or unstable pre-existing medical, psychiatric disorder, or other condition that could interfere with the participant*s safety, obtaining informed consent, or compliance to the study procedures.
17. Is or has an immediate family member (e.g., spouse, parent/legal guardian,
sibling or child) who is investigational site or sponsor staff directly involved with this trial, unless prospective Institutional Review Board (IRB) approval (by chair or designee) is given allowing exception to this criterion for a specific participant.
18. Prior treatment with the following agents:
* Tumor necrosis factor receptor (TNFR) agonists, including OX40, CD27, CD137 (4-1BB), CD357 (glucocorticoid-induced TNFR family-related gene) at any time.
* TLR4 agonist at any time.
* Anticancer therapy or investigational therapy within 30 days or 5 half-lives of the drug, whichever is shorter.
* Prior radiation therapy: permissible if at least 1 non-irradiated measurable lesion is available for assessment according to RECIST version 1.1 or if a solitary measurable lesion was irradiated, objective progression is documented. A wash out of at least 14 days before start of study treatment for radiation of any intended use to the extremities for bone metastases and 28 days for radiation to the chest, brain, or visceral organs is required.
19. Prior allogeneic or autologous bone marrow transplantation or other solid organ transplantation.
20. Toxicity from previous treatment including:
* Toxicity Grade *3 related to prior immunotherapy and that lead to study treatment discontinuation.
* Toxicity related to prior treatment has not resolved to Grade *1 (except alopecia, or endocrinopathy managed with replacement therapy).
21. Received transfusion of blood products (including platelets or red blood cells) or administration of colony stimulating factors (including G-CSF, granulocyte- macrophage colony-stimulating factor, and recombinant erythropoietin) within 2 weeks before the first dose of study treatment.
22. Major surgery within 4 weeks before the first dose of study treatment. Participants must have also fully recovered from any surgery (major or minor) and/or its complications before initiating study
treatment.
23. Known drug or alcohol abuse.
24. Receipt of any live vaccine within 4 weeks.