How does nature make decisions?
Biology decides without anyone deciding. The same architecture — a capacitor loading to threshold, a factory building, a reactor meeting, a homeostat conserving — appears in a T cell, a falling leaf, a fly laying an egg. Read the cycle, and what the clinician is doing changes.
Completing the Chen–Mellman Cancer-Immunity Cycle
The Chen–Mellman cancer-immunity cycle has organised tumour immunology for thirteen years. Alongside its successes, clinical observations have accumulated that the cycle as drawn cannot resolve: PD-L1 predicts at AUC 0.63, response rates vary from 70% to 2% across cancer types with the same drug, cold tumours stay cold for reasons the cycle cannot name. This paper proposes that the seven Mellman steps are a true description of six of sixteen positions, and that the missing ten are where the unanswered questions live. Across 33 cancer types, only 4 stall at the synapse where anti-PD-1 acts.