ORLANDO – The BET inhibitor CPI-0610, given alone or in combination with ruxolitinib, has demonstrated activity in a phase 2 trial of patients with relapsed/refractory myelofibrosis (MF).
Responses were best among transfusion-dependent patients who received CPI-0610 and ruxolitinib. All but one of these patients experienced symptom improvement.
In the monotherapy group, results were best among transfusion-independent patients. All of these patients had an improvement in Patient Global Impression of Change (PGIC) score, and most had a 50% or greater improvement in total symptom score (TSS).
of the Icahn School of Medicine at Mount Sinai, New York, presented these results from the phase 2 MANIFEST trial ( ) at the annual meeting of the American Society of Hematology.
Dr. Mascarenhas presented data on 90 patients – 59 with primary MF, 16 with post–polycythemia vera MF, 13 with post–essential thrombocythemia MF, and 2 whose type of MF was unknown. At baseline, the patients’ median age was 69 years and 76.7% of patients had received at least 6 months of ruxolitinib treatment.
Of the 36 patients who received CPI-0610 monotherapy, 34 were still receiving the treatment as of Oct. 17, 2019. Of the 54 patients treated with CPI-0610 and ruxolitinib, 41 were still receiving the combination at that time. The median duration of treatment was 11.3 weeks in the monotherapy arm and 25.9 weeks in the combination arm. Responses were assessed at 24 weeks.
“CPI-0610 monotherapy or added on to ruxolitinib in a relapsed/refractory MF population demonstrated antitumor activity, as evidenced by spleen and symptom improvement,” Dr. Mascarenhas said. “Symptom responses were observed in a majority of patients. We treated these patients, and they felt much better. It was impressive.”
Efficacy of monotherapy
There were two evaluable patients who had been transfusion dependent at baseline and received CPI-0610 monotherapy for at least 24 weeks. Neither patient achieved transfusion independence, and neither had a spleen volume reduction of at least 35% (SVR35). One patient had a 50% or greater improvement in TSS, and one had an improvement in PGIC score.
There were seven evaluable patients who were transfusion independent at baseline and received CPI-0610 for at least 24 weeks. None of these patients had an SVR35 response, three of five evaluable patients had a 50% or greater improvement in TSS, and all seven had an improvement in PGIC score.
Efficacy of the combination
There were 14 patients who had been transfusion dependent at baseline and received CPI-0610 and ruxolitinib for at least 24 weeks. Six of these patients had become transfusion independent at week 24.
Among the patients who were transfusion dependent at baseline, 25% (3/12) had an SVR35 response at week 24, 54% (7/13) had a 50% or greater improvement in TSS, and 75% (9/12) had an improvement in PGIC score.
There were 13 evaluable patients who were transfusion independent at baseline and received CPI-0610 and ruxolitinib for at least 24 weeks. None of these patients had an SVR35 response, 38% had a 50% or greater improvement in TSS, and 69% had an improvement in PGIC score.