Abstract 1938

Background:

Carfilzomib (CFZ), a selective, epoxyketone proteasome inhibitor, produces potent, sustained proteasome inhibition and lacks many of the off-target activities associated with bortezomib (BTZ). Durable single-agent activity with CFZ has been observed in patients (pts) with relapsed/refractory multiple myeloma (R/R MM) who have received multiple prior therapies as well as in pts with advanced stage disease or significant comorbidities (Jagannath et al. ASCO 2009 Meeting. Abstract 8504). PX-171-004, is an ongoing Phase 2 study of single-agent CFZ in pts with relapsed or refractory MM following 1–3 prior therapies. Here we present updated data on the BTZ-naïve pts and report on activity observed in pts with significant comorbidities or poor-risk cytogenetic or FISH markers for myeloma.

Methods:

Enrolled pts received either 20 mg/m2 for all treatment cycles, or a stepped-up, dose-escalating regimen of 20 mg/m2 for Cycle 1 and 27 mg/m2 for all treatment cycles thereafter. CFZ was administered on Days 1, 2, 8, 9, 15 and 16 every 28 days (one cycle), for a maximum of 12 cycles. Dexamethasone, 4mg, was administered prior to CFZ in Cycle 1 only. For the present analyses, pts were stratified according to several baseline criteria including ECOG performance score, cytogenetic or FISH markers of high-risk disease per mSMART criteria [del17p, t(4;14), t(14;16), del13 by karyotype and hypodiploidy] and serum ß2-microglobulin. The primary endpoint was overall response rate (ORR) per International Uniform Response Criteria for Multiple Myeloma.

Results:

Data are available for 110 BTZ-naïve pts. Baseline pt characteristics included: 60% of ECOG PS ≥1; 53% baseline neuropathy Grade 1/2; 30% moderately impaired renal function (CrCl <60 mL/min), and 17% diabetes. Approximately 13% of pts had cytogenetic or FISH markers of poor prognosis. The ORR for the entire BTZ-naïve population was 48%; the ORR for BTZ-naïve pts receiving 20–27 mg/m2 was 54%. The ORRs stratified according to dose and baseline measurements are detailed in the following table.

Table 1:
NORR n (%)
Dosing group   
    Overall 110 53 (48%) 
    20 mg/m2 only 56 24 (43%) 
    20-27 mg/m2 54 29 (54%) 
Baseline measurement   
    ECOG performance status   
    0 44 22 (50%) 
    ≥1 66 28 (42%) 
     Cytogenetics or FISH   
        Normal/favorable 84 39 (46%) 
        Poor 15 6 (40%) 
        Unknown 11 5 (45%) 
    Serum ß2-microglobulin   
        <2.5 26 14 (54%) 
        ≥2.5 55 22 (41%) 
        ISS Stage   
        I, II or unknown 93 43 (46%) 
        III 17 7 (41%) 
NORR n (%)
Dosing group   
    Overall 110 53 (48%) 
    20 mg/m2 only 56 24 (43%) 
    20-27 mg/m2 54 29 (54%) 
Baseline measurement   
    ECOG performance status   
    0 44 22 (50%) 
    ≥1 66 28 (42%) 
     Cytogenetics or FISH   
        Normal/favorable 84 39 (46%) 
        Poor 15 6 (40%) 
        Unknown 11 5 (45%) 
    Serum ß2-microglobulin   
        <2.5 26 14 (54%) 
        ≥2.5 55 22 (41%) 
        ISS Stage   
        I, II or unknown 93 43 (46%) 
        III 17 7 (41%) 

The most common treatment-emergent AEs, regardless of relationship to study drug, were fatigue (61%), nausea (43%), anemia (39%), dyspnea (36%), cough (34%), headache (31%), thrombocytopenia and upper respiratory infections (30% each) and were primarily ≤ Grade 2 in severity. Grade 3/4 AEs occurring in >5% of pts included lymphopenia, neutropenia, pneumonia, thrombocytopenia, anemia and fatigue. Of note, there were no discontinuations for peripheral neuropathy and only 1 pt with impaired renal function at baseline was discontinued for creatinine increases. Twenty-four pts remain on study and 23% have completed the protocol-specified 12 cycles of therapy. Seventeen pts (20%) elected to continue CFZ on an extended treatment protocol (PX-171-010); no cumulative toxicities have been noted.

Conclusions:

Single-agent CFZ achieves high response rates in BTZ-naïve pts with relapsed myeloma, with minimal neuropathy, even in the setting of high-risk disease. In addition, single-agent CFZ continues to demonstrate long-term tolerability even in pts with comorbid conditions, including renal insufficiency and diabetes, who may benefit from a steroid-sparing treatment regimen. The data from this ongoing trial show that CFZ is a promising new treatment for multiple myeloma in the relapsed or refractory setting.

Disclosures:

Vij:Onyx: Honoraria. Kaufman:Celgene: Consultancy, Research Funding; Millenium: Consultancy; Merck: Research Funding. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; Centocor Ortho Biotec: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Jagannath:Millenium, OrthoBiotec, Celgene, Merck, Onyx: Honoraria; Imedex, Medicom World Wide, Optum Health Education, PER Group: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Alsina:Millenium: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy. Gabrail:Millenium: Research Funding. Vesole:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millenium: Speakers Bureau. Le:Onyx Pharmaceuticals: Employment. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: Research Funding.

Author notes

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Asterisk with author names denotes non-ASH members.

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