Introduction and objectivesAddiction concerns people suffering from great psychological vulnerability due to early trauma and attachment disorders. Although several forms of therapeutic management have been shown to be effective, the relapse rate remains high, and the effects are short-lived. Therefore, the first objective of this study was to integrate the tenets and concepts of compassion-based therapy with acceptance and commitment therapies for the treatment of patients with polyaddictions by conceptualizing a therapeutic program aimed at support for maintaining abstinence. The interest in such an integration has been raised by several authors. The central concept of that integrative approach was the “compassionate flexibility”. Our second objective was to explore the feasibility, acceptability, and therapeutic effects of this intervention for patients with polyaddictions and psychiatric comorbidities, who are particularly resistant to psychotherapies. Material and methodTwelve patients (8 men and 4 women) with polyaddictions (alcohol, cocaine, tobacco, cannabis) of the 24 referred for the study, followed the MyActaddiction program. The A-B multiple-case-series protocol combined qualitative and quantitative measures to monitor feasibility, acceptability, clinical (OCDS, EADS-21) and psychological (AAQ-II, EAC) progress, patient narrative feedback (perception, connection, sense of presence), complemented by follow-up observations on abstinence maintenance. ResultsResults show moderate feasibility, with only 50 % of study referrals accessing psychotherapy, good accessibility, with 66 % of patients completing all sessions, high satisfaction levels and positive qualitative feedback. Pre- and post-treatment assessments showed a significant clinical improvement in craving (obsessive thoughts and OCDS total score) at group level, and these changes were clinically significant at individual level by Reliable Change Index measures, for 70 % of participants. On the EDAS-21 scale, patients who had pathological scores prior to therapy improved their scores to non-pathological thresholds for anxiety, stress and depression. The Reliability Change Index (RCI) showed that the resulting change was clinically significant at the individual level for 83 % of patients on anxiety level, for 58.33 % of patients on depression, and 50 % of patients on the stress level. In terms of the psychological processes targeted by the therapeutic practices, we observed an improvement in psychological flexibility, with a clinically significant reduction in AAQ-II scores after the intervention compared to the pre-treatment score. The RCI indicated that the observed clinical change was significant. There was also a significant increase in post-test versus pre-test for two dimensions of self-compassion: “common humanity” and “mindfulness”, with a high Cohen's d. Regarding individual scores, the scores for “self-compassion” and “common humanity” were below the expected average scores usually observed in the general population. According to the RCI, the increase in post-test scores was robust for 41 % of the patients on “common humanity” dimension, for only on patient on the “mindfulness” dimension, and on patient on the “self-kindness” dimension. The RCI shows that changes are clinically reliable for 50 % of patients for the “common humanity” and “mindfulness” sub-dimensions of self-compassion. Follow-up showed that 66 % of patients-maintained abstinence at one year, while 25 % relapsed, while one patient experienced both variations in consumption and periods of abstinence. ConclusionThe present program combines TFC and ACT for abstinence maintenance in the treatment of addiction. This study could demonstrate the value of process-based approaches to the treatment of complex pathologies such as polyaddiction. These findings suggest that compassion-based psychological interventions and psychological flexibility could be a transdiagnostic protective factor encouraging abstinence maintenance in people with polyaddictions. These results call for further research to explore the active mechanisms of compassion-related components.