A Study to Investigate Safety and Tolerability of TransCon IL-2 β/γ Alone or in Combination With Pembrolizumab and/or Chemotherapy or TransCon TLR7/8 Agonist in Adult Participants With Locally Advanced or Metastatic Solid Tumor Malignancies

Key Inclusion Criteria:

At least 18 years of age
Demonstrated adequate organ function at screening
Life expectancy >12 weeks as determined by the Investigator
At least 1 lesion of measurable disease, except for Post Anti-PD-1 Melanoma and 2L+ Cervical Cancer (at least 2 lesions of measurable disease)
Female and male participants of childbearing potential who are sexually active must agree to use highly effective methods of contraception
Participants must have histologically confirmed locally advanced, recurrent, or metastatic solid tumor malignancies that cannot be treated with curative intent (surgery or radiotherapy), with the exception of the neoadjuvant cohorts
Part 1 and Part 2: Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2
Part 3: Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
Part 1 and Part 2: Participants who have undergone treatment with anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibody must have a washout of at least 4 weeks from the last dose and evidence of disease progression per investigator assessment before Cycle 1 Day 1 (C1D1)
Part 1 and Part 2: Participants who have previously received an immunotherapy prior to C1D1 must have any immune-related toxicities resolved to ≤Grade 1 or baseline (prior to the immunotherapy) to be eligible, with the exception of participants on well controlled physiologic endocrine replacement
Part 3: Part 3, neoadjuvant cohorts: participants must have completely resectable disease

Key Exclusion Criteria:

Symptomatic central nervous system metastases
Active autoimmune diseases, regardless of need for immunosuppressive treatment, with the exception of participants well controlled on physiologic endocrine replacement
Any uncontrolled bacterial, fungal, viral, or other infection
Significant cardiac disease
A marked clinically significant baseline prolongation of QT/QTc interval (e.g., repeated demonstration of a QTc interval >480 ms) [CTCAE Grade 1]) using Fridericia's QT correction formula
Positive for HIV or has known active hepatitis B or C infection
Known hypersensitivity to any study treatment(s) used in the specific study part/cohort
Participants who have been previously treated with IL-2 or IL-2 variants (all participants), or TLR agonist (Part 3 only for Post Anti-PD-1 Melanoma, 2L+ Cervical Cancer, and Neoadjuvant Melanoma)
Systemic immunosuppressive treatment with the exception for patients on corticosteroid taper (for example, for chronic obstructive pulmonary disease exacerbation).
Vaccination with live, attenuated vaccines within 4 weeks of C1D1
Treatment with any other anti-cancer systemic treatment (approved or investigational) or radiation therapy within 4 weeks of C1D1
Part 3: Other active malignancies within the last 2 years
Women who are breastfeeding or have a positive serum pregnancy test during screening