Mark Bower

Importance: Gut dysbiosis impairs response to immune checkpoint inhibitors (ICIs) and can be caused by broad-spectrum antibiotic (ATB) therapy. Objective: To evaluate whether there is an association between ATB therapy administered concurrently (cATB) or prior (pATB) to ICI therapy and overall survival (OS) and treatment response to ICI therapy in patients with cancer treated with ICIs in routine clinical practice. Design, Setting, and Participants: This prospective, multicenter, cohort study conducted at 2 tertiary academic referral centers recruited 196 patients with cancer who received ICI therapy between January 1, 2015, and April 1, 2018, in routine clinical practice rather than clinical trials. Main Outcomes and Measures: Overall survival calculated from the time of ICI therapy commencement and radiologic response to ICI treatment defined using the Response Evaluation Criteria in Solid Tumors (version 1.1), with disease refractory to ICI therapy defined as progressive disease 6 to 8 weeks after the first ICI dose without evidence of pseudoprogression. Results: Among 196 patients (137 men and 59 women; median [range] age, 68 [27-93] years) with non-small cell lung cancer (n = 119), melanoma (n = 38), and other tumor types (n = 39), pATB therapy (HR, 7.4; 95% CI, 4.3-12.8; P < .001), but not cATB therapy (HR, 0.9; 95% CI, 0.5-1.4; P = .76), was associated with worse OS (2 vs 26 months for pATB therapy vs no pATB therapy, respectively) (hazard ratio [HR], 7.4; 95% CI, 4.2-12.9) and a higher likelihood of primary disease refractory to ICI therapy (21 of 26 [81%] vs 66 of 151 [44%], P < .001). Overall survival in patients with non-small cell lung cancer (2.5 vs 26 months, P < .001), melanoma (3.9 vs 14 months, P < .001), and other tumor types (1.1 vs 11, P < .001) was consistently worse in those who received pATBs vs those who did not. Multivariate analyses confirmed that pATB therapy (HR, 3.4; 95% CI, 1.9-6.1; P < .001) and response to ICI therapy (HR, 8.2; 95% CI, 4.0-16.9; P < .001) were associated with OS independent of tumor site, disease burden, and performance status. Conclusions and Relevance: Despite being limited by sample size, geographic origin, and the lack of correlative analyses on patients' gut microbiota, this study suggests that pATB therapy but not cATB therapy is associated with a worse treatment response and OS in unselected patients treated with ICIs in routine clinical practice. Mechanistic studies are urgently required to investigate ATB-mediated alterations of gut microbiota as a determinant of poorer outcome following ICI treatment.

BACKGROUND: The role of prophylactic antibacterial agents after chemotherapy remains controversial. METHODS: We conducted a randomized, double-blind, placebo-controlled trial in patients who were receiving cyclic chemotherapy for solid tumors or lymphoma and who were at risk for temporary, severe neutropenia (fewer than 500 neutrophils per cubic millimeter). Patients were randomly assigned to receive either 500 mg of levofloxacin once daily or matching placebo for seven days during the expected neutropenic period. The primary outcome was the incidence of clinically documented febrile episodes (temperature of more than 38 degrees C) attributed to infection. Secondary outcomes included the incidence of all probable infections, severe infections, and hospitalization but did not include a systematic evaluation of antibacterial resistance. RESULTS: A total of 1565 patients underwent randomization (784 to placebo and 781 to levofloxacin). The tumors included breast cancer (35.4 percent), lung cancer (22.5 percent), testicular cancer (14.4 percent), and lymphoma (12.8 percent). During the first cycle of chemotherapy, 3.5 percent of patients in the levofloxacin group had at least one febrile episode, as compared with 7.9 percent in the placebo group (P<0.001). During the entire chemotherapy course, 10.8 percent of patients in the levofloxacin group had at least one febrile episode, as compared with 15.2 percent of patients in the placebo group (P=0.01); the respective rates of probable infection were 34.2 percent and 41.5 percent (P=0.004). Hospitalization was required for the treatment of infection in 15.7 percent of patients in the levofloxacin group and 21.6 percent of patients in the placebo group (P=0.004). The respective rate of severe infection was 1.0 percent and 2.0 percent (P=0.15), with four infection-related deaths in each group. An organism was isolated in 9.2 percent of probable infections. CONCLUSIONS: Among patients receiving chemotherapy for solid tumors or lymphoma, the prophylactic use of levofloxacin reduces the incidence of fever, probable infection, and hospitalization.

PURPOSE: The effect of highly active antiretroviral therapy (HAART) on the incidence of non-AIDS-defining cancers (NADCs) is unclear. METHODS: We have investigated the occurrence of NADCs in a prospective cohort of 11,112 HIV-positive individuals, with 71,687 patient-years of follow-up. Standardized incidence ratios (SIRs) were calculated using general population incidence data. We investigated the effect of calendar period, HIV parameters, and immunologic and treatment-related factors on the incidence of these cancers using univariate and multivariate analyses. RESULTS: The SIR for all NADCs was 1.96 (95% CI, 1.66 to 2.29). There was no significant excess in incidence in the pre-HAART era (1983 to 1995; SIR, 0.95; 95% CI, 0.58 to 1.47). However, the incidence increased in the early HAART period (1996 to 2001) and remains elevated in the most recent established HAART period (2002 to 2007; SIR, 2.05; 95% CI, 1.51 to 2.72, and SIR 2.49; 95% CI, 2.00 to 3.07, respectively). Multivariate analysis showed that use of HAART (hazard ratio [HR] = 1.64; 95% CI, 1.13 to 2.39) and a nadir CD4 count less than 200/microL (HR = 1.67; 95% CI, 1.10 to 2.54) were associated with an increased risk. Only the non-nucleoside reverse transcriptase inhibitors (NNRTIs) were associated with a significantly increased risk of NADCs (HR = 1.45; 95% CI, 1.01 to 2.08). Much of this association was attributable to an increased risk of Hodgkin's lymphoma with NNRTIs (HR = 2.20; 95% CI, 1.03 to 4.69). CONCLUSION: Since the introduction of HAART, there has been a significantly increased risk of NADCs, which has now stabilized. A number of factors are associated with this increased risk, including HAART use. There may be an association between the use of NNRTIs and the development of Hodgkin's lymphoma.