No abstract

Regulators of G protein signaling (RGS) proteins accelerate GTP hydrolysis by G␣ subunits, thereby attenuating signaling. RGS4 is a GTPase-activating protein for G i and G q class ␣ subunits. In the present study, we used knockouts of G q class genes in mice to evaluate the potency and selectivity of RGS4 in modulating Ca 2؉ signaling transduced by different G q -coupled receptors. RGS4 inhibited phospholipase C activity and Ca 2؉ signaling in a receptor-selective manner in both permeabilized cells and cells dialyzed with RGS4 through a patch pipette. Receptor-dependent inhibition of Ca 2؉ signaling by RGS4 was observed in acini prepared from the rat and mouse pancreas. The response of mouse pancreatic acini to carbachol was about 4-and 33-fold more sensitive to RGS4 than that of bombesin and cholecystokinin (CCK), respectively. RGS1 and RGS16 were also potent inhibitors of G q -dependent Ca 2؉ signaling and acted in a receptor-selective manner. RGS1 showed approximately 1000-fold higher potency in inhibiting carbachol than CCK-dependent signaling. RGS16 was as effective as RGS1 in inhibiting carbachol-dependent signaling but only partially inhibited the response to CCK. By contrast, RGS2 inhibited the response to carbachol and CCK with equal potency. The same pattern of receptorselective inhibition by RGS4 was observed in acinar cells from wild type and several single and double G q class knockout mice. Thus, these receptors appear to couple G q class ␣ subunit isotypes equally. Difference in receptor selectivity of RGS proteins action indicates that regulatory specificity is conferred by interaction of RGS proteins with receptor complexes.

IMPORTANCE Patients with osteoarthritis (OA) may remain symptomatic with traditional OA treatments. OBJECTIVE To assess 2 subcutaneous tanezumab dosing regimens for OA. DESIGN, SETTING, AND PARTICIPANTS A randomized, double-blind, multicenter trial from January 2016 to May 14, 2018 (last patient visit). Patients enrolled were 18 years or older with hip or knee OA, inadequate response to OA analgesics, and no radiographic evidence of prespecified joint safety conditions. INTERVENTIONS Patients received by subcutaneous administration either tanezumab, 2.5 mg, at day 1 and week 8 (n = 231); tanezumab, 2.5 mg at day 1 and 5 mg at week 8 (ie, tanezumab, 2.5/5 mg; n = 233); or placebo at day 1 and week 8 (n = 232). MAIN OUTCOMES AND MEASURES Co-primary end points were change from baseline to week 16 in Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) Pain (0-10, no to extreme pain), WOMAC Physical Function (0-10, no to extreme difficulty), and patient global assessment of osteoarthritis (PGA-OA) (1-5, very good to very poor) scores. RESULTS Among 698 patients randomized, 696 received 1 or more treatment doses (mean [SD] age, 60.8 [9.6] years; 65.1% women), and 582 (83.6%) completed the trial. From baseline to 16 weeks, mean WOMAC Pain scores decreased from 7.1 to 3.6 in the tanezumab, 2.5 mg, group; 7.3 to 3.6 in the tanezumab, 2.5/5 mg, group; and 7.3 to 4.4 in the placebo group (least squares mean differences [95% CI] vs placebo were −0.60 [−1.07 to −0.13; P = .01] for tanezumab, 2.5 mg, and −0.73 [−1.20 to −0.26; P = .002] for tanezumab, 2.5/5 mg). Mean WOMAC Physical Function scores decreased from 7.2 to 3.7 in the 2.5-mg group, 7.4 to 3.6 in the 2.5/5-mg group, and 7.4 to 4.5 with placebo (differences vs placebo, −0.66 [−1.14 to −0.19; P = .007] for tanezumab, 2.5 mg, and −0.89 [−1.37 to −0.42; P < .001] for tanezumab, 2.5/5 mg). Mean PGA-OA scores decreased from 3.4 to 2.4 in the 2.5-mg group, 3.5 to 2.4 in the 2.5/5-mg group, and 3.5 to 2.7 with placebo (differences vs placebo, −0.22 [−0.39 to −0.05; P = .01] for tanezumab, 2.5 mg, and −0.25 [−0.41 to −0.08; P = .004] for tanezumab, 2.5/5 mg). Rapidly progressive OA occurred only in tanezumab-treated patients (2.5 mg: n = 5, 2.2%; 2.5/5 mg: n = 1, 0.4%). The incidence of total joint replacements was 8 (3.5%), 16 (6.9%), and 4 (1.7%) in the tanezumab, 2.5 mg; tanezumab, 2.5/5 mg; and placebo groups, respectively. CONCLUSIONS AND RELEVANCE Among patients with moderate to severe OA of the knee or hip and inadequate response to standard analgesics, tanezumab, compared with placebo, resulted in statistically significant improvements in scores assessing pain and physical function, and in PGA-OA, although the improvements were modest and tanezumab-treated patients had more joint safety events and total joint replacements. Further research is needed to determine the clinical importance of these efficacy and adverse event findings.

Objective. To compare the efficacy of tanezumab versus placebo for reducing pain and improving physical function in patients with osteoarthritis (OA) of the hip.Methods. This was a 32-week, randomized, double-blind, placebo-controlled, phase III trial. Patients with baseline Western Ontario and McMaster Universities OA Index (WOMAC) Pain and Physical Function subscale scores of >5 and >4, respectively, and patient's global assessment of OA as "fair," "poor," or "very poor" were treated at baseline and weeks 8 and 16. Coprimary efficacy end points were change from baseline to week 16 in WOMAC Pain and Physical Function subscales and patient's global assessment, analyzed using analysis of covariance. Adverse events (AEs) were monitored throughout.Results. Patients (n ‫؍‬ 621) were randomized 1:1:1:1 to treatment with intravenous tanezumab 2.5 mg, 5 mg, or 10 mg or placebo. Each tanezumab group showed significant improvement for the 3 coprimary end points versus placebo (P < 0.001 for all). AE incidence ranged from 55% to 58% across tanezumab groups versus 44% for placebo. Safety findings were similar to those previously reported. The tanezumab OA clinical program was temporarily placed on hold because of AEs leading to joint replacement. Total joint replacements were reported in 8 patients: 1 in the 10 mg, 2 in the 5 mg, 2 in the 2.5 mg, and 3 in the placebo group. A total of 9 joints were replaced (8 hips [7 index joints] and 1 shoulder).Conclusion. Our findings indicate that tanezumab provides superior pain relief and improvement in physical function and patient's global assessment versus placebo in patients with painful hip OA, and is generally well tolerated.

NCT00864097.