Impact of cytotoxic and targeted antineoplastic drugs on the validity of the mitogen-induced interferon-gamma release assay for latent tuberculosis infection: results of a prospective trial at a comprehensive cancer center.

Rodriguez GH, Safdar A.

Scand J Infect Dis. 2014 Jan;46(1):52-7.

Abstract The T-SPOT.TB test (TS.TB), an interferon-gamma (IFN-γ) release assay
(IGRA), is superior in diagnosing latent tuberculosis infection compared with the
conventional tuberculin skin test (TST). However, whether cytotoxic chemotherapy
and treatment with new-generation antineoplastic monoclonal antibodies affects
the TS.TB is not certain. We evaluated the feasibility of using the TS.TB in this
population. Sixteen cancer patients at high risk for tuberculosis exposure were
prospectively evaluated with the TST and TS.TB. Blood samples were obtained 7.5 ±
89.3 days after the most recent cycle of antineoplastic therapy. Six patients
(38%) were febrile within 24 h of blood sampling; high-dose corticosteroid
therapy and profound treatment-induced neutropenia were present in 1 patient
each. In all patients, TS.TB showed no evidence of latent tuberculosis infection.
A robust mitogen-induced IFN-γ response was seen in samples from 14 patients
(88%) despite therapy with high-dose corticosteroids, cyclophosphamide,
fludarabine, gemtuzumab ozogamicin, and alemtuzumab. The presence of fever or
profound neutropenia did not negatively impact mitogen response by peripheral
lymphocytes. The 2 patients whose peripheral blood lymphocytes (> 500 cells/ml)
failed to generate a cytokine response to ex vivo mitogen stimulation had
refractory advanced cancer. Unlike the TST, a negative TS.TB provided
interpretable results even in cancer patients undergoing new-generation
immunosuppressive therapy.