Which agent is more likely to cause a hypersensitivity reaction after multiple prior doses?

• A. Carboplatin
• B. Paclitaxel
• C. Rituximab
• D. Cetuximab

Answer: (A)

Hypersensitivity reactions can become more likely with cumulative exposure to certain chemotherapy drugs. Carboplatin, a platinum-based agent, is classic for developing an allergic reaction after several cycles. As patients receive more doses, the immune system can become sensitized to platinum-containing complexes, increasing the chance of an immediate hypersensitivity reaction on subsequent exposure. Reactions to this drug class often emerge after multiple prior doses, sometimes around the sixth cycle or later.

In contrast, infusion reactions with other agents tend to occur earlier in therapy: rituximab and cetuximab commonly provoke reactions during initial or early infusions, and paclitaxel hypersensitivity is typically seen early and is often related to its solvent. Therefore, after several prior doses, the drug most likely to cause a hypersensitivity reaction is carboplatin.