In this study, the potential effects of bacteria on the efficacy of frequently used chemotherapies was examined. Bacteria and cancer cell lines were examined in vitro and in vivo for changes in the efficacy of cancer cell killing mediated by chemotherapeutic agents. Of 30 drugs examined in vitro, the efficacy of 10 was found to be significantly inhibited by certain bacteria, while the same bacteria improved the efficacy of six others. HPLC and mass spectrometry analyses of sample drugs (gemcitabine, fludarabine, cladribine, CB1954) demonstrated modification of drug chemical structure. The chemoresistance or increased cytotoxicity observed in vitro with sample drugs (gemcitabine and CB1954) was replicated in in vivo murine subcutaneous tumour models. These findings suggest that bacterial presence in the body due to systemic or local infection may influence tumour responses or off-target toxicity during chemotherapy.

Infiltration of tumours by regulatory T cells confers growth and metastatic advantages by inhibiting anti-tumour immunity and by production of RANK ligand, which may directly stimulate metastatic propagation of RANK-expressing cancer cells. Modulation of regulatory T cells can enhance the efficacy of cancer immunotherapy. Strategies include depletion, interference with function, inhibition of tumoural migration and exploitation of T cell plasticity. Problems with these strategies include a lack of specificity, resulting in depletion of anti-tumour effector T cells or global interruption of regulatory T cells, which may predispose to autoimmune diseases. Emerging technologies such as RNA interference and tetramer-based targeting may have the potential to improve selectivity and efficacy.

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The level of an endogenous opioid (peak B endorphin) was measured in chromatographically fractionated cerebrospinal fluid (CSF) sampled from two groups of chronic pain patients before and after intrathecal saline (placebo) injection. As assessed by a verbal rating scale, one group reported no change in their level of pain (non-responders, NR; n = 6) while the other group reported complete or greater than 50% pain relief (placebo responders, PR; n = 14). We find, as has been reported previously, that initial peak B levels were lower (by 50%) in these chronic pain patients' CSF than in CSF from pain-free (PF) normal controls (P less than 0.001, t-test). Peak B levels measured from CSF of the NR group undergoing this procedure did not change (P greater than 0.4, paired t-test). In contrast, a significant 2.3-fold increase was measured in the CSF peak B level of the PR group (P less than 0.05, paired t-test). This is the first direct evidence that a CSF opioid is correlated with placebo pain relief in chronic pain patients. Peak B is a potent analgesic substance when administered by the intracerebroventricular route in mice and its level is related to the patients' pain status in a presumably causal manner.