It is apparent that new safe drugs for adequate pain control should be designed for cancer patients. One of the areas is the creation of selective molecules interacting with the μ1-opioid receptors devoid of many side effects of opioids. Such a drug (t is Tafalgin) has been designed in Russia, while it has no foreign analogues.

OBJECTIVE

To evaluate the efficacy and safety of the analgesic Tafalgin in cancer patients with chronic pain syndrome (CPS), to confirm the hypothesis that Tafalgin is not less effective than morphine.

SUBJECTS AND METHODS

An open-label, comparative, multicenter, randomized, Phase III clinical trial was conducted in 5 clinical centers to investigate the efficacy and safety of Tafalgin in cancer patients with CPS. The patients were randomized into 2 groups: 1) 120 subjects received subcutaneous Tafalgin only; 2) 59 took morphine tablets for 28 days (Period 1) and then Tafalgin for 28 days (Period 2). The primary efficacy endpoint was a 28-day analgesic response rate. CPS was assessed using 0 to 10 numerical rating scale (NRS), a 5-point Likert scale for patients and physicians, and the 36-Item Short Form Health Survey (SF-36). Safety analysis was carried out, by estimating the frequency and severity of adverse events (AEs).

RESULTS

A total of 179 patients (an intention-to-treat (ITT) population) were examined; 143 patients (a per protocol (PP) population) completed the examination. The proportion of patients with a maintained 28-day analgesic response was 98.97% in Group 1 and 100% in Group 2 for the PP population (p=0.6783). For the ITT population, the proportion of patients with a maintained 28-day analgesic response was 84.17% in Group 1 and 88.14% in Group 2 (p=0.4787). There were no cases of ineffective therapy with Tafalgin. The mean baseline NRS scores in the PP population were 0.42±0.48 and 0.30±0.47 in Groups 1 and 2 (p=0.1250); the 28-day scores were 0.38±0.44 and 0.28±0.30 in these groups (p=0.3472). In the ITT population: the baseline NRS scores were 0.53±0.61 and 0.51±0.81 in Groups 1 and 2 (p=0.3519); the 28-day scores were 0.54±0.81 and 0.41±0.50, respectively (p=0.4536). After being switched from morphine to Tafalgin, the patients maintained an adequate pain control at 56 and 84 days after therapy. A lower incidence of AEs was determined when tafalgin was administered.

CONCLUSION

Tafalgin has a pronounced analgesic effect, which is highly competitive with that of morphine in the treatment of CPS in cancer patients, and has a favorable safety profile and a lower incidence of AEs than morphine.