A Phase 2 Study of RO7490677 In Participants With Myelofibrosis

ORR was defined as the percent of participants with a response according to the International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) criteria. This was defined as those participants who achieved clinical improvement (CI), partial remission (PR), or complete remission (CR) at a post-baseline assessment of treatment response OR had at least stable disease (SD) for three consecutive end-of-cycle response assessments (e.g. Day 1 of the subsequent cycle) in conjunction with improvement in the bone marrow fibrosis score relative to baseline by at least one grade at any time point during the period of stable disease.

Response rate was defined as the percent of participants with a reduction in bone marrow fibrosis by at least one grade according to World Health Organization (WHO) criteria from baseline to any time during the study. This was determined by a central adjudication panel of expert hematopathologists, blinded to participant, treatment, and time of biopsy.

ORR was defined as the percent of participants with a response according to the IWG-MRT criteria. This was defined as those participants who achieved CI, PR, or CR at a post-baseline assessment of treatment response OR had at least SD for three consecutive end-of-cycle response assessments (e.g. Day 1 of the subsequent cycle) in conjunction with improvement in the bone marrow fibrosis score relative to baseline by at least one grade at any time point during the period of stable disease. Participants who achieved a clinical benefit in the main phase had the opportunity to remain on treatment. The determination of ORR in the main phase is outlined in the arms description below. Participants who didn't achieve a benefit had the opportunity to switch to a different dosing schedule in the OLE phase. The determination of ORR in the OLE phase is outlined in the arms descriptions below.

Defined as the percent of participants with a reduction in bone marrow fibrosis score by at least one grade according to WHO criteria at any time during the study. As determined by a central adjudication panel of expert hematopathologists, blinded to participant, treatment, and time of biopsy. Participants in the main phase had the opportunity to remain on treatment (as outlined in the arms description below). Participants also had the option to switch to the OLE phase after completing 9 cycles of the originally assigned treatment and receive PRM-151 10 mg/kg/Q4W (as outlined in the arms description below).

Bone marrow response was defined as a reduction in bone marrow fibrosis score by at least one grade from baseline at anytime during the study.

The MPN-SAF TSS total symptom score was the sum of the following 10 items: Filling up quickly when you eat (early satiety), abdominal discomfort, inactivity, Problems with concentration, Worst fatigue, Night sweats, Itching, Bone pain, Fever and Unintentional weight loss last 6 months. The MPN-SAF Total Symptom Score had a possible range of 0 to 100, where a lower score was more favorable. The values reported are the change from baseline scores.

Response rate was defined as the percent of participants with a reduction in bone marrow fibrosis by at least one grade according to World Health Organization (WHO) criteria at any time during the study. This was determined by a central adjudication panel of expert hematopathologists, blinded to participant, treatment, and time of biopsy.

Reduction in bone marrow fibrosis score: Reduction of at least one grade from baseline. Bone marrow fibrosis grades according to WHO criteria (as determined by central adjudication).

Duration of response was defined as time from first decrease from baseline >= 1 grade to time of return to baseline levels.

Hemoglobin improvement was measured by the percent of participants with: Red cell transfusion independence (no transfusions for >= 12 consecutive weeks) OR 50% reduction in red blood cell (RBC) transfusions for >= 12 consecutive weeks OR percent of participants with >= 10 g/L and >= 20 g/L increase in hemoglobin for >= 12 consecutive weeks without transfusions (outcome parameter assessed was dependent on baseline hemoglobin/transfusion status).

Platelet improvement was measured by the percent of participants with: Platelet transfusion independence (no transfusions for >= 12 consecutive weeks) OR 50% reduction in platelets transfusions for >= 12 consecutive weeks OR doubling of baseline platelet count for >= 12 consecutive weeks without platelet transfusions OR platelet count > 50 x 10e9/L for >=12 consecutive weeks without platelet transfusions OR doubling of baseline platelet count for >= 12 consecutive weeks without platelet transfusions OR platelet count > 25 x 10e9/L for >= 12 consecutive weeks without platelet transfusions (outcome parameter assessed is dependent on baseline platelet status).

Symptom improvement was assessed as the percent of participants with 50% reduction in MPN-SAF TSS from baseline over time. The MPN-SAF TSS total symptom score was the sum of the following 10 items: Filling up quickly when you eat (early satiety), abdominal discomfort, inactivity, Problems with concentration, Worst fatigue, Night sweats, Itching, Bone pain, Fever and Unintentional weight loss last 6 months. The MPN-SAF Total Symptom Score had a possible range of 0 to 100, where a lower score was more favorable.

Best Overall Response: (CR, PR, CI), SD and PD according to the IWG-MRT Criteria.

Cmax is the maximum observed RO7490677 plasma concentration.

Time at which the maximum plasma concentration was observed.

Area under the plasma concentration time curve from time 0 to time of last measurable plasma concentration.

Area under the plasma concentration-time curve from 0-time extrapolated to infinity.

Apparent terminal elimination half-life of RO7490677.

An AE was defined as any noxious, pathologic, or unintended change in anatomical, physiologic, or metabolic function as indicated by physical signs, symptoms, or laboratory changes occurring in any phase of a clinical study, whether or not considered investigational product-related. Pre-existing conditions which worsened during the study were also considered as adverse events. IRRs were considerd to be Adverse Events of Special Interest (AESI). Grading was completed according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE), version 4.0.

An SAE was defined as any AE that occurred at any dose the resulted in death; was life-threatening; required hospitalization or prolongation of existing hospitalizations; a persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions; a congenital anomaly or birth defect. An AE was defined as any noxious, pathologic, or unintended change in anatomical, physiologic, or metabolic function as indicated by physical signs, symptoms, or laboratory changes occurring in any phase of a clinical study, whether or not considered investigational product-related. Pre-existing conditions which worsened during the study were also considered as adverse events. Grading was completed according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE), version 4.0.