Long-Acting Injectable Helped Adults With Schizophrenia Remain Relapse-Free

A study showed that 96% of patients with schizophrenia remained relapse-free with every-6-month dosing of the long-acting injectable paliperidone palmitate (Invega Hafyera) through up to 3 years, researchers reported during a poster presentation at the recent Psych Congress 2023.

In this exclusive MedPage Today video, study author Christoph Correll, MD, of the Feinstein Institutes for Medical Research at Northwell Health in Manhasset, New York, explains the study’s design, results, and conclusions.

Following is a transcript of his remarks:

Hi, everyone. I’m going to present the poster titled, “Efficacy and safety of paliperidone palmitate 6-month formulation, a 3-year analysis in adults with schizophrenia.”

In terms of background, patients with schizophrenia do require long-term treatment with antipsychotics. However, individuals with schizophrenia often struggle — as you know and I know — with consistent medication adherence and that can lead to poor outcomes, mainly driven by relapses. Long-acting injectable antipsychotics, or LAIs, have the potential to improve adherence and thereby symptom control in patients with schizophrenia who are then able to also achieve more of their long-term goals.

Paliperidone palmitate once every 6 months (or PP6M) is the first LAI with a substantially longer dosing interval of every 6 months (twice yearly). The analysis we presented were of patients who were followed from a double-blind randomized controlled trial through a 2-year single-arm open-label extension study, and that assessed the long-term efficacy and safety of PP6M in adults with schizophrenia for up to 3 years, a period that’s rarely assessed that long.

Patients were 18 to 70 years of age that had a DSM-5 diagnosis of schizophrenia and a PANSS [Positive and Negative Syndrome Scale] total score of less than 70. So they were already stabilized in the first year of that randomized double-blind trial, comparing 6-monthly and 3-monthly paliperidone, which were non-inferior, both compared together.

Patients receiving the PP6M arm who completed the 1-year double-blind study continued for up to 2 years in an open-label extension phase. And those were then included in the analysis.

The primary efficacy endpoint was assessment of relapse events. Secondary assessments included the PANSS total and subscale scores, CGI [Clinical Global Impression] severity, so that’s illness severity score, and the PSP, or Personal and Social Performance Score looking at the functionality. Furthermore, safety assessments were also included.

A total of 121 patients were included in this 3-year intention-to-treat analysis, meaning everyone who finished the 1-year double-blind study was then followed for however long they stayed in up until the duration of 3 years. Mean age of the patients was 39 years, most were male, and the mean duration of illness was 11 years. So these were your multi-episode patients.

In terms of the survival rate, the relapse rate over the 3 years after 1-year stabilization was an amazingly low 4.1%. So, 96% of patients who had made it through the first year then remained relapse-free for the next 2 years. That’s an enormously low number. Participants also treated with PP6M were clinically stable and well-maintained, which was evidenced by the PANSS total, the CGI severity, and the PSP — the functional scores, that are very well remaining stable.

Overall, 80.2% of patients had at least one adverse event, but these were usually mild and did not lead to discontinuation. The most common TEAEs [treatment-emergent adverse events] occurring at least 10% were headache, weight increase, prolactin increase — or hyperprolactinemia, nasopharyngitis, and injection site pain. But those [that] were related to the PP6M were very few, and also leading to drug withdrawal in only 5.8% and 5.0%.

Some limitations need to be mentioned, and there was no comparative group in the 3-year study. And basically, additionally, patients who started on PP6M and relapsed or discontinued during the double-blind phase were not included, and also those not opting to go into the open-label extension phase. Then the open-label extension phase was limited to six participating countries, so the data may not be fully generalizable to all countries.

In conclusion, a 3-year intent-to-treat analysis of 121 patients on PP6M demonstrated that 95.9% of patients remained relapse-free beyond the 1 year up to the end of 3 years. There were no new safety signals identified, no deaths were reported. So these results support the long-term efficacy and safety of the 2-yearly, or twice-a-year, dosing of PP6M up to 3 years in adults with schizophrenia who can benefit from the long-term stability of their illness.

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