On December 5, 2016 Stemline Therapeutics, Inc. (Nasdaq:STML) reported the oral presentation of positive clinical data from its ongoing SL-401 Phase 2 potentially pivotal clinical trial in blastic plasmacytoid dendritic cell neoplasm (BPDCN) (Press release, Stemline Therapeutics, DEC 5, 2016, View Source [SID1234516936]). The trial results were delivered via an oral presentation by Naveen Pemmaraju, M.D., from the University of Texas MD Anderson Cancer Center, on Sunday morning at the 2016 American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting, being held at the San Diego Convention Center in San Diego, CA. Schedule your 30 min Free 1stOncology Demo! The full presentation is now available on the Stemline website, under the "Scientific Presentations" tab (see link: View Source).
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The Phase 2 BPDCN data presented at ASH (Free ASH Whitepaper) cover 32 evaluable adult BPDCN patients treated with SL-401. Results demonstrated that SL-401 produced a 100% (16/16) overall response rate (ORR), including an 81% (13/16) complete response (CR) rate in first-line BPDCN patients treated at the recommended dose of 12 ug/kg/day and a 95% (18/19) ORR in first-line patients treated at the recommended dose or lower. In relapsed/refractory patients, the ORR was 69% (9/13) with a CR rate of 31% (4/13). See Tables 1 and 2 for a summary of efficacy and safety.
Response duration data continue to appear promising, with 69% (11/16) first-line BPDCN patients treated at 12 ug/kg/day remaining relapse-free (range: 1+ to 20+ months, ongoing). This includes four patients receiving SL-401 therapy (range: 1+ to 15+ months, ongoing), six patients in durable remission from SL-401 who were then successfully bridged to stem cell transplant (SCT) and remain in remission (range: 5+ to 20+ months progression-free after first SL-401 dose), and one additional patient undergoing SCT preparation. In the relapsed/refractory setting, 46% (6/13) patients are relapse-free (range: 1+ to 7+ months). This includes five patients receiving SL-401 therapy (range: 1+ to 4+ months, ongoing) and one patient in durable remission from SL-401 who was then successfully bridged to SCT and remains in remission for approximately 8+ months, ongoing. The median progression-free and overall survival for first-line has not been reached and for relapsed/refractory it is currently 8.5 months.
Naveen Pemmaraju, M.D., Assistant Professor, Department of Leukemia at the University of Texas MD Anderson Cancer Center (Houston, TX), an investigator on the study, commented, "The encouraging results generated to date with SL-401 continue to indicate the agent could very well emerge as the standard of care for both first-line and relapsed/refractory BPDCN, a devastating disease for which there had previously been no effective therapy. In addition to strong clinical activity, manifested by high levels of durable responses, the safety profile with SL-401 continues to be predictable and manageable over increasing patient experience." Dr. Pemmaraju continued, "Together with Stemline, we are working to bring this promising new agent to patients as expeditiously as possible in BPDCN and other malignancies."
Andrew A. Lane, M.D., Ph.D., Assistant Professor, Medical Oncology at the Dana-Farber Cancer Institute (Boston, MA), and a co-investigator on the study, commented, "The clinical outcomes seen with SL-401 in first-line and relapsed/refractory BPDCN continue to be exciting, particularly given that these are two greatly under-served patient populations. SL-401 has also begun to show early promising signs in other clinical settings." Dr. Lane continued, "We are very pleased to be ongoing contributors to this study, and look forward to helping to advance this active agent in BPDCN and other hematologic malignancies as well."
Table 1. SL-401 Summary of Clinical Efficacy
Line of Therapy First-line First-line R/R All lines
Dose Group All Doses 12 ug/kg 12 ug/kg All Doses
n (evaluable/total) 19 16 13 32
ORR 18/19 (95%) 16/16 (100%) 9/13 (69%) 27/32 (84%)
CR*, n (rate) 14 (74%) 13 (81%) 4 (31%) 18 (56%)
Bridged to SCT, n 6 6 1 7 (22%)
(allo+auto) (3+3) (3+3) (1+0) (4+3)
*CR includes CRi (CR with incomplete hematopoietic recovery) and CRc (CR in non-skin organs and gross reduction in cutaneous lesions with residual microscopic disease).
Table 2. Most Common Adverse Events (≥ 15% treatment-related adverse effects, TRAEs)
All Grades (% of patients) Grade ≥ 3 (% of patients)
TRAEs All AEs TRAEs All AEs
Transaminase elevation 52 60 40 42
Hypoalbuminemia 39 42 0 0
Chills 31 35 0 0
Pyrexia 27 42 0 0
Nausea 23 46 0 0
Fatigue 23 42 0 8
Thrombocytopenia 19 19 19 19
Hypotension 19 19 0 0
Weight increased 19 27 0 0
Capillary leak syndrome (CLS) 19 19 8 8
Anemia 19 31 11 15
Decreased appetite 19 23 0 0
Edema peripheral 23 46 0 0