IO102-IO103: Side Effects

Safety Overview#

IO102-IO103 has been evaluated in the phase 1/2 MM1636 trial (30 patients), the phase 3 IOB-013/KN-D18 trial (407 patients), and phase 2 basket trials in NSCLC and HNSCC. A consistent and important finding across all trials is that the addition of IO102-IO103 to checkpoint inhibitor therapy does not increase the frequency or severity of immune-mediated adverse events -- a critical differentiator from other immunotherapy combinations.

Vaccine-Specific Side Effects#

Injection Site Reactions#

The only adverse event consistently attributed to the IO102-IO103 vaccine component:

• Frequency: Common (reported across all trials)
• Severity: Low-grade (grade 1-2), transient
• Manifestations: Erythema, induration, mild pain at the injection site
• Mechanism: Expected local immune response to peptide-Montanide emulsion
• Management: Self-limiting; no treatment discontinuation required

No Systemic Vaccine-Specific Toxicity#

In the phase 1/2 trial, the systemic toxicity profile was comparable to nivolumab monotherapy. In the phase 3 trial, no increased frequency of immune-mediated or treatment-related side effects was observed with the combination compared to pembrolizumab alone. This is a notable finding because:

• Other immunotherapy combinations (e.g., ipilimumab + nivolumab) substantially increase grade 3-4 AE rates (~60%)
• Even dual antibody approaches (nivolumab + relatlimab) moderately increase AE rates
• IO102-IO103 appears to enhance anti-tumor immunity without amplifying autoimmune toxicity

Checkpoint Inhibitor-Associated Adverse Events#

The adverse events observed with IO102-IO103 + checkpoint inhibitor combinations are those expected from the checkpoint inhibitor component:

Common Immune-Related AEs#

Management#

Standard immune-related adverse event management applies:

• Monitoring per checkpoint inhibitor guidelines
• Corticosteroid initiation for grade 2+ immune-related AEs
• Checkpoint inhibitor dose delay or discontinuation per standard protocols
• Endocrine replacement therapy (e.g., levothyroxine) as needed

Safety Across Tumor Types#

The favorable safety profile has been consistent across all tumor types studied:

• Melanoma (Phase 1/2): No systemic toxicity beyond nivolumab monotherapy in 30 patients
• Melanoma (Phase 3): No increased immune-mediated AEs vs pembrolizumab alone in 407 patients
• NSCLC (Phase 2): Safety consistent with prior trials
• HNSCC (Phase 2): No added significant systemic toxicity

Contraindications#

The contraindications for IO102-IO103 are primarily driven by the checkpoint inhibitor component:

• Active autoimmune disease: Requiring systemic immunosuppressive therapy (standard checkpoint inhibitor contraindication)
• Hypersensitivity: To IO102-IO103 peptides, Montanide ISA-51 adjuvant, or the checkpoint inhibitor
• Organ transplant recipients: At risk of graft rejection with checkpoint inhibitor therapy
• Severe hepatic impairment: Per checkpoint inhibitor labeling

Drug Interactions#

Immunosuppressive Agents#

Systemic immunosuppression may blunt vaccine-induced T cell responses:

• Corticosteroids above 10 mg/day prednisone equivalent are generally avoided prior to and during vaccination
• Short courses of corticosteroids for irAE management are permitted per clinical trial protocols
• Other immunosuppressants (methotrexate, azathioprine) would be expected to impair vaccine efficacy

Checkpoint Inhibitors#

IO102-IO103 is designed for and has been tested exclusively with checkpoint inhibitors. The combination is synergistic rather than antagonistic -- the vaccine activates anti-tumor T cells, while checkpoint inhibitors prevent their suppression.

Related Reading#

• IO102-IO103 overview and research guide
• IO102-IO103 dosing protocols
• IO102-IO103 risks and legal status