Clinical development of anticancer drugs can be enhanced using efficacy data of small population clinical trials.

WHAT IS KNOWN AND OBJECTIVE: Although there are accelerated approval pathways based on data of small populations and surrogate endpoints, the concern that these pathways authorize the use of inefficacious drugs based on limited data from earlier phase clinical trials remains. We retrospectively investigated the efficacy of anticancer drugs, which were approved or whose development was terminated in small and large clinical trials, and verified whether small clinical trials could reflect the results for efficacy in large clinical trials. METHODS: All anticancer drugs approved in Japan or whose development was terminated from 2015 to 2019 were searched. The median overall survival (OS), median progression-free survival (PFS), and overall response rates (ORR) between small clinical trials (sample size ≤100) and large clinical trials (sample size >100) with identical target populations and treatment settings were compared. Simple linear regression analysis, Spearman's correlation analysis, and paired sample t-test were performed. RESULTS AND DISCUSSION: A total of 61 comparable small and large clinical trials were identified. For all endpoints, statistically significant linear trends and correlation were detected (p < 0.001). There were no statistically significant differences in the median PFS and ORR between small and large clinical trials. The mean differences of both clinical trials were -0.102 months and -1.531%, respectively. WHAT IS NEW AND CONCLUSION: Even when the sample size of the clinical trial was increased, the efficacy data of anticancer drugs could not be changed significantly. These results supported the accelerated approval pathway based on the promising efficacy data of small populations in anticancer drug development.

Antitumor effect of inhalatory lipopolysaccharide and synergetic effect in combination with cyclophosphamide.

BACKGROUND: Macrophage cells differentiate into killer macrophages, named M1 macrophages, that effectively eliminate cancer cells by generating cytokines. We examined the feasibility of a lung cancer therapy using lipopolysaccharide (LPS), which triggers this differentiation. It is expected that the delivery via inhalation of LPS directly into the lungs, where alveolar macrophages reside abundantly, would be effective at minimizing the possible toxic effect of LPS. MATERIALS AND METHODS: We determined the effects of intratracheal insufflation of LPS on (i) the exudation of lactate dehydrogenase, (ii) generation of tumor necrosis factor-α and interleukin-12, and (iii) tumor metastases in Lewis lung carcinoma-bearing C57BL/6 mice. RESULTS: Pulmonary insufflation of LPS resulted in a consistent accumulation of tumor necrosis factor-α, and transient increase in interleukin-12 without significant release of lactate dehydrogenase from the lung cells. In addition, a significant antitumor effect of LPS was observed; and this antitumor effect was potentiated by combination of LPS with the antitumor agent cyclophosphamide. CONCLUSION: Pulmonary inhalation of LPS combined with a chemotherapeutic agent is a promising approach to lung cancer therapy.

Cytotoxic effects of activated alveolar macrophages on lung carcinoma cells via cell-to-cell contact and nitric oxide.

AIM: It is possible that macrophages may be effective for cancer treatment because once activated, lung macrophages have enhanced contact with lung tumor cells and have a cytotoxic effect. In this paper, we report that nitric oxide (NO) produced by lung macrophages activated with lipopolysaccharide (LPS) suppressed cell growth of human lung adenocarcinoma cells. MATERIALS AND METHODS: A549, a lung adenocarcinoma cell line, was cultured with NR8383, a rat alveolar macrophage cell line, in the presence and absence of LPS. The effect of LPS on the growth rate of A549 cells was examined as a function of NO production under cell-to-cell contact conditions. RESULTS: NR8383 cells showed potent cytostatic and cytocidal effects on A549 cells when both cells were co-cultured in the presence of LPS. These effects were mainly due to the production of NO, but another possible mechanism, such as cell-to-cell contact, may also be involved. CONCLUSION: Activation of alveolar macrophages by LPS suppresses the growth of lung carcinoma cells via NO production under cell-to-cell contact conditions.

Lipopolysaccharide-activated alveolar macrophages having cytotoxicity toward lung tumor cells through cell-to-cell binding-dependent mechanism.

BACKGROUND: In lung tumor biotherapy, local macrophages such as alveolar macrophages and tumor-associated macrophages (TAMs) which normally exist in contact with tumor cells are thought to be hopeful target. It is advantageous to clarify the potential for and mechanism by which lung tumor cells are killed by the neighboring macrophages in order to establish new lung cancer therapy using a drug delivery system to lung tissue. MATERIALS AND METHODS: A549, a human lung adenocarcinoma cell line, and Lewis lung carcinoma LLC1, a mouse lung cancer cell line, were co-cultured with NR8383, a rat alveolar macrophage cell line, and AMJ2-C11, a mouse alveolar macrophage cell line, at a ratio of 1:10 and 1:5, respectively. Macrophages were activated with lipopolysaccharide (LPS) and cytotoxicity toward tumor cells was evaluated by a dye-uptake method and (3)H-thymidine release assay, respectively. Nitric oxide (NO) production was estimated by Griess assay, and tumor necrosis factor (TNF)-α and interleukin (IL)-1ß were measured by ELISA. RESULTS: Significant macrophage cell aggregation and cytotoxicity against A549 cells and LLC1 cells was observed with NR8383 cells and AMJ2-C11 cells in the presence of LPS. A high concentration of NO and TNF-α were detected in the supernatant of co-culture medium with LPS. Inhibition of cell-to-cell contact restored A549 cell growth. CONCLUSION: The LPS-activated alveolar macrophages demonstrated an increased cell-to-cell contact with lung tumor cells and inducing cytotoxicity with production of NO and cytokines TNF-α and IL-1ß. These results suggest that moderate activation of local macrophages in lung (alveolar macrophages and TAMs) is thought to be a hopeful means of establishing new immunotherapy for lung cancer.