Sustained regression of a tislelizumab-reactivated tuberculous focus after short-course therapy: a case report.

[BACKGROUND] Immune checkpoint inhibitors (ICIs) are considered potential risk factors for latent tuberculosis infection (LTBI). Radiologically stable, inactive tuberculous focus activation provides particularly compelling evidence for this association. While a complete course of antituberculosis treatment is unequivocally recommended for conventional active tuberculosis, the management of ICI-activated tuberculosis lacks consensus and poses a particularly significant therapeutic dilemma, especially when combination therapy with anticancer agents results in severe adverse effects.

[CASE PRESENTATION] A 69-year-old man with stage IV lung squamous cell carcinoma and a long-term radiologically stable, untreated pulmonary tuberculous focus underwent chemoimmunotherapy with paclitaxel, carboplatin, and tislelizumab. The malignant mass regressed after four cycles, but the previously stable tuberculous focus was reactivated, as confirmed by next-generation sequencing. Anti-tuberculosis therapy is complicated by severe synergistic toxicity with chemotherapy, leading the patient to self-discontinue after two months. Notably, the reactivated granulomatous lesion regressed to its original baseline size without a full course of anti-TB treatment. The patient continued tislelizumab maintenance, and both lesions remained stable at the 10-month follow-up.

[CONCLUSION] This case suggests that a short course of anti-TB therapy aimed at reducing the bacterial burden may constitute a viable management strategy for ICI-induced reactivation of a stable TB focus, potentially enabling the safe continuation of ICIs. This observation challenges the conventional requirement for a complete anti-TB course in this specific scenario and suggests a personalized management approach on the basis of the dynamic balance between bacterial load and host immunity.