ALBERT

Description: Background.This study aimed to determine the progression-free survival and response rate using early therapeutic intervention in patients with high-risk smoldering multiple myeloma (SMM) using the combination of ixazomib, lenalidomide, and dexamethasone. Methods.Patients enrolled on study met eligibility for high-risk SMM based on the newly defined criteria proposed by Rajkumar et al. (Blood 2014). The treatment plan was designed to be administered on an outpatient basis where patients receive 9 cycles of induction therapy of ixazomib (4mg) at days 1, 8, and 15, in combination with lenalidomide (25mg) at days 1-21 and dexamethasone at days 1, 8, 15, and 22. The induction phase was followed by ixazomib (4mg) and lenalidomide (15mg) maintenance for another 15 cycles. A treatment cycle was defined as 28 consecutive days for a total of 24 months period. Bone marrow samples of all patients were obtained before starting therapy for baseline assessment for minimal residual disease (MRD) testing, whole-exome sequencing (WES), and RNA sequencing of plasma and bone marrow microenvironment cells. Moreover, blood samples were obtained at screening and before each cycle for isolating cell-free DNA (cfDNA) and circulating tumor cells (CTCs). Results.In total, 53 of the planned 62 patients have been enrolled in this study from February 2017 to May 2019. The median age of the patients enrolled was 61 years (range, 41 to 84) with 22 male (41.5%). The analysis was conducted on patients who have completed at least 1 cycle of therapy (n=45). The median follow-up for the trial is 14.4 months (range: 2- 27.6). Interphase fluorescence in situ hybridization (iFISH) was successful in 37 patients (82.2%). High-risk cytogenetics (defined as the presence of t(4;14), 17p deletion, and 1q gain) were found in 20 patients (54%). The median number of cycles completed was 14 cycles (range: 1-24). According to the study's inclusion criteria, baseline markers showed that 15, 14, and 13 patients had 3, 4, and 5 high-risk features, respectively. Moreover, 24 patients (53.3%) met the criteria of high-risk SMM, according to the Mayo 2018 model. The most common grade 3 adverse events were hypertension (6.3%), hypophosphatemia (4.2%), and rash (4.2%). Grade 4 thrombocytopenia and neutropenia were each reported in 4.4% of patients, and hyperglycemia was reported in 2.2%. Stem cells were collected in all eligible patients by the end of the induction phase. As of the abstract date, the overall response rate (partial response or better) in participants who completed at least 1 cycle of treatment was 91.1% (41/45), with 14 Complete Responses (CR, 31.1%), 9 very good partial responses (VGPR, 20%), 18 partial responses (40%), and 4 minimal Responses (MR, 10%). ORR in patients who completed the induction phase (≥9 cycles) was 97% (n= 32/33), with 14(42.4%) and 9 (27.2%) having CR and VGPR, respectively. All patients who had a CR have also achieved a stringent CR. Six patients have completed the treatment protocol and are currently on follow-up. As of July 2019, none of the patients have progressed to overt MM. MRD testing by next-generation sequencing is ongoing for patients who achieved CR or VGPR and will be presented at the meeting. Conclusion.The combination of ixazomib, lenalidomide, and dexamethasone is an effective and well-tolerated intervention in high-risk smoldering myeloma with 91% ORR and 54.7% CR and VGPR to date. The high response rate, convenient schedule and manageable toxicity build on prior studies which have shown efficacy of lenalidomide and dexamethasone in high risk smoldering myeloma. Longer follow-up for disease outcome is ongoing. Disclosures Bustoros, MD: Takeda: Honoraria. Nadeem:Celgene: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Sanofi: Consultancy. Prescott:Janssen: Equity Ownership. Munshi:Takeda: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Adaptive: Consultancy; Abbvie: Consultancy; Abbvie: Consultancy; Adaptive: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Takeda: Consultancy; Oncopep: Consultancy; Oncopep: Consultancy; Amgen: Consultancy; Janssen: Consultancy. Anderson:OncoPep: Other: Scientific founder ; C4 Therapeutics: Other: Scientific founder ; Gilead Sciences: Other: Advisory Board; Janssen: Other: Advisory Board; Sanofi-Aventis: Other: Advisory Board. Richardson:Oncopeptides: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Ghobrial:Amgen: Consultancy; Celgene: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; Takeda: Consultancy. OffLabel Disclosure: Ixazomib, Lenalidomide and Dexamethasone is an investigational combination in high-risk smoldering multiple myeloma and has not been approved by the US Food and Drug Administration or any other regulatory agency worldwide for the use under investigation.

Description: Background: Induction chemoimmunotherapy followed by autologous stem cell transplantation (ASCT) is a standard of care for transplant eligible (TE) patients (pts) with untreated mantle cell lymphoma (uMCL); however, there is no consensus on the optimal induction regimen. The addition of rituximab + high-dose cytarabine (RC) to an RCHOP-like regimen is associated with better outcomes. In addition, two randomized trials have demonstrated superior efficacy and tolerability for rituximab/bendamustine (RB) compared to RCHOP for uMCL. Based on this, we conducted a phase 2 trial of 3 cycles of RB followed by 3 cycles of RC in 23 TE pts with uMCL, with encouraging preliminary results (Armand, BJH 2016). Pts continued to be followed for relapse and survival. Meanwhile, RB/RC became the standard frontline regimen at Dana-Farber Cancer Institute (DFCI). Simultaneously, investigators at Washington University in St. Louis (WUSTL) initiated a similar study of alternating cycles of RB/RC for uMCL. Herein, we report the results of both phase 2 trials as well as the off-trial experience. Methods: In the DFCI trial, TE pts (age 18-69) with uMCL were treated with 3 cycles of RB (R 375 mg/m2 d1, B 90 mg/m2 d1-2) followed by 3 cycles of RC (R 375 mg/m2 d1, C 3gm/m2 BID d1-2 with dose reductions for age, renal dysfunction, or pre-existing neurotoxicity). Off-trial pts treated with RB/RC at DFCI or in consulting community practices were retrospectively identified using clinical and pharmacy databases. In the WUSTL trial, TE pts (age 18-65) received alternating cycles of RB (cycles 1, 3, 5) and RC (cycles 2, 4, 6) (same dosing as above). Response assessments were made using CT scans for the DFCI trial and PET/CT for the WUSTL trial and DFCI off-trial pts. Results: In total, 86 pts (23 DFCI trial, 49 DFCI off-trial, 14 WUSTL trial) were treated with RB/RC. The median age was 57 (range 30-72). Pts in the WUSTL cohort were more likely to be male, have a high MIPI score, and have blastoid variant (Table). 94% of pts completed 6 cycles of RB/RC therapy. Off-trial pts were more likely to receive a lower starting dose (≤ 2gm/m2) of cytarabine (76%) compared to trial pts (38%). At the EOI, the overall response rate and CRR were 98% and 92%, respectively, with similar response rates across cohorts (Table). 73 pts (85%) subsequently underwent ASCT and 4 additional pts (5%) have ASCTs planned. 9 pts did not undergo ASCT because of persistent or PD (n=3), prolonged cytopenias (n=3), an incidentally identified ASXL1 mutation without cytopenias (n=1), pt preference (n=1), and inadequate stem cell collection (n=1). Delayed platelet engraftment after ASCT was seen for pts receiving alternating cycles of RB/RC compared to sequential RB/RC at day 30 (plts

Description: Background: Autologous stem cell transplantation (ASCT) can be curative for patients (pts) with relapsed/refractory Hodgkin lymphoma (HL) who are sensitive to salvage therapy, particularly for pts who achieve a complete metabolic response (CMR) before ASCT. Pts who fail multiple salvage regimens have inferior outcomes and are generally considered poor candidates for ASCT. Recent studies suggest that anti-PD-1 monoclonal antibodies (mAbs) may restore sensitivity to cytotoxic therapy in HL pts with previously chemorefractory disease. We hypothesized that PD-(L)1 mAb-based salvage therapy may therefore also improve ASCT outcomes for HL pts who had failed salvage therapy. Methods: Medical records were reviewed at 13 US transplant centers to identify pts with a diagnosis of classic HL who failed at least 2 systemic therapies, were treated with a PD-1 or PD-L1 mAb (either alone or in combination) as 3rd line or later therapy, and subsequently underwent ASCT. Results: 44 eligible pts were identified. The median age was 33 (range 19-68). Pts received ABVD (39), AVD (2), brentuximab vedotin (BV) + AVD (1), Stanford V (1), or eBEACOPP (1) as 1st line therapy. 26 pts (59%) were refractory to 1st line treatment and 8 additional pts (18%) relapsed within 12 months. High-risk clinical features were observed frequently at 1st relapse including extranodal involvement (47%), B symptoms (27%), and advanced stage (64%). Pts received PD-(L)1 based treatment after failing 2 lines (32%), 3 lines (57%), or ≥4 lines (11%) of therapy. 32 pts (73%) were refractory to the line of therapy before PD-(L)1, 25 pts (57%) to 2 consecutive lines before PD-(L)1, and 10 pts (22%) to 3 consecutive lines before PD-(L)1. 16 pts (36%) were refractory to ≥2 salvage therapies immediately before PD-(L)1 therapy and 17 (39%) were refractory to all prior treatments. 39 pts (89%) received BV or a BV-based combination before ASCT. 67% were BV-refractory, including 86% of those receiving BV monotherapy. Pts received a median of 6 doses of a PD-(L)1 mAb (range 2-26) either as monotherapy (75%) or as part of a PD-1 based combination (25%). The median time from last dose of PD-(L)1 mAb to ASCT was 54 days (range 12-386). Best response to PD-(L)1-based therapy was CR (53%), PR (33%), SD (12%), or PD (2%). The median number of systemic therapies (including PD-(L)1) before ASCT was 4 (range 3-7) and 12 pts (27%) received intervening salvage therapy between PD-(L)1 treatment and ASCT. Pre-ASCT PET status was CR in 31 pts (70%), PR in 9 (18%), SD in 4 (9%), and PD in 1 (2%). There were no ASCT-related deaths. 2 pts developed BCNU pneumonitis and 1 developed engraftment syndrome. All 3 pts responded to steroids. 14 pts (32%) have received maintenance therapy with BV (4), a PD-1 mAb (8), or BV + PD-1 mAb (2). 4 pts (9%) received consolidative radiation. With a median post-ASCT follow-up of 12.2 months, progression-free survival (PFS) at 1 yr was 91% [95CI 75-97]. Notably, resistance to chemotherapy before PD-(L)1 therapy did not predict worse post-ASCT outcomes (see Table). 1-yr PFS was 90% for pts who were refractory to the 3 lines of therapy before PD-(L)1, 93% for pts refractory to ≥2 salvage therapies immediately before PD-(L)1, and 90% for pts refractory to all prior treatments. Favorable 1-yr PFS was also seen among pts who received PD-(L)1 as 4th or later line therapy (88% vs 100% for pts receiving PD-[L]1 as 3rd line, p=0.17) and among pts who failed to achieve a CMR on pre-ASCT PET (1-yr PFS 81% vs 96% for CMR pts, p=0.34). Lack of response to PD-(L)1 therapy (1-yr PFS 67% vs 96%, p=0.04), receipt of intervening salvage therapy (1-yr PFS 72% vs 100%, p=0.026), and increasing age (HR 1.11, p=0.015) were all significant predictors of inferior PFS. 1-yr overall survival was 100%. Conclusions: This high-risk cohort is heterogenous in terms of number of prior therapies and degree of chemoresistance, but excellent post-ASCT outcomes were observed among even the most heavily pre-treated, chemorefractory subgroups. Outcomes for PD-(L)1 responders were particularly favorable with a 1-yr PFS of 96%, suggesting that response to PD-(L)1 rather than prior chemotherapy may be the more important predictor of post-ASCT outcomes in this pt population. While longer follow-up is required to confirm the durability of these remissions, ASCT can be considered for HL pts responding to PD-(L)1 based salvage therapy, even if they have previously demonstrated a high degree of chemoresistance. Table Disclosures Nieto: Novartis: Research Funding; Astra-Zeneca: Research Funding; Affimed: Research Funding; Affimed: Consultancy. Byrne:Karyopharm: Research Funding. Maddocks:BMS: Research Funding; Novartis: Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding. Svoboda:BMS: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Merck: Research Funding; Incyte: Research Funding; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy; Celgene: Research Funding; Kyowa: Consultancy; Kite: Consultancy. McGuirk:Juno Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ArticulateScience LLC: Other: Assistance with manuscript preparation; Pluristem Ltd: Research Funding; Gamida Cell: Research Funding; Kite Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Research Funding; Fresenius Biotech: Research Funding; Astellas: Research Funding; Bellicum Pharmaceuticals: Research Funding. Advani:Kyowa Kirin Pharmaceutical Developments, Inc.: Consultancy; Millennium: Research Funding; Janssen: Research Funding; Cell Medica, Ltd: Consultancy; Regeneron: Research Funding; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Stanford University: Employment, Equity Ownership; Agensys: Research Funding; Kura: Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Forty-Seven: Research Funding; Celmed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding; Seattle Genetics: Consultancy, Research Funding; Infinity Pharma: Research Funding; Gilead Sciences, Inc./Kite Pharma, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Cohen:Seattle Genetics, Inc.: Consultancy, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Takeda Pharmaceuticals North America, Inc.: Research Funding; Gilead/Kite: Consultancy; LAM Therapeutics: Research Funding; UNUM: Research Funding; Hutchison: Research Funding; Astra Zeneca: Research Funding; ASH: Research Funding; Lymphoma Research Foundation: Research Funding; Genentech, Inc.: Consultancy, Research Funding; Janssen Pharmaceuticals: Consultancy. Frigault:Xenetic: Consultancy; Foundation Medicine: Consultancy; Novartis: Consultancy; Nkarta: Consultancy; Juno/Celgene: Consultancy; Kite/Gilead: Honoraria; Incyte: Consultancy. Chen:Magenta: Consultancy; Takeda: Consultancy; Incyte: Consultancy; Kiadis: Consultancy; Abbvie: Consultancy. Lynch:Johnson Graffe Keay Moniz & Wick LLP: Consultancy; Rhizen Pharmaceuticals S.A: Research Funding; Juno Therapeutics: Research Funding; Takeda Pharmaceuticals: Research Funding; Incyte Corporation: Research Funding; T.G. Therapeutics: Research Funding. Smith:Seattle Genetics: Research Funding; Denovo Biopharma: Research Funding; Ayala (spouse): Research Funding; Merck Sharp & Dohme Corp: Consultancy, Research Funding; Acerta Pharma BV: Research Funding; Incyte Corporation: Research Funding; Ignyta (spouse): Research Funding; Genentech: Research Funding; Bristol-Myers Squibb (spouse): Research Funding; Portola Pharmaceuticals: Research Funding; Pharmacyclics: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ho:Jazz Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Consultancy; Omeros Corporation: Membership on an entity's Board of Directors or advisory committees. Armand:Affimed: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sigma Tau: Research Funding; Infinity: Consultancy; Otsuka: Research Funding; Genentech: Research Funding; Pfizer: Consultancy; ADC Therapeutics: Consultancy; Tensha: Research Funding; Roche: Research Funding; Adaptive: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Herrera:Merck: Consultancy; BMS: Consultancy; Genentech: Research Funding; Adaptive Biotechnologies: Consultancy; Gilead Sciences: Research Funding; KiTE/Gilead: Consultancy; Genentech: Consultancy; Merck: Research Funding; Astra-Zeneca: Research Funding; Seattle Genetics: Consultancy; BMS: Research Funding; Seattle Genetics: Research Funding.

Description: Objective 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) is used routinely for response assessment and treatment decision making in Hodgkin lymphoma and B cell non-Hodgkin lymphoma. The predictive value of PET/CT in patients with peripheral T-cell lymphomas (PTCL) is not well defined. We performed a retrospective single institution analysis to determine the utility of pre-transplant PET/CT to predict outcomes following autologous stem cell transplant (ASCT) for PTCL. Materials and Methods PET/CT patient population We screened the Dana-Farber Cancer Institute database for patients undergoing ASCT between 2005 and 2015 and identified 109 PTCL patients. Patients had PET/CT performed within 3 months prior to transplant and follow up PET/CT within one year of ASCT. 38 patients met the inclusion criteria (17 women, 21 men, mean age at transplant 56 years, SD ±14.6, range 22-73). Image interpretation The FDG-PET/CT images were reviewed on HERMES GOLD (Hermes Medical Solutions AB, Stockholm, Sweden) workstation by a radiologist (AON) blinded to clinical details. Pre-transplant PET/CT images were read initially and then one week later the post-transplant PET/CT images were read with the reader blinded to the pre-transplant PET/CT findings. The Deauville five-point scale was used for staging and assessment of treatment response and recurrence. A Deauville score of 3 or less was considered a complete response (CR). Results There was mean of 1.3 months between the initial PET/CT and transplant. Mean of 5 months between transplant and follow up PET/CT. A total of 30 patients had a CR on pre-transplant PET/CT. There were 8 patients with persistent sites of FDG uptake on PET/CT with Deauville 4 (n=4), Deauville 5 (n=2) consistent with partial response to treatment. Pre-transplant PET/CT did not correlate with long term survival outcomes including 3-year PFS in our data; a negative pre-transplant PET/CT was not associated with improved 3-year PFS as compared to a positive pre-transplant PET/CT. A total of 26 patients (68%) had no evidence of disease on post-transplant PET or negative post treatment PET/CT. Of those, 23 (88%) had a 3 -year progression free survival, 13 (50%) had a 5-year progression free survival, and 5 (19%) had died of recurrent disease at the time of our analysis. On post-transplant, a total of 12 patients had positive PET/CT with 6 achieving partial remission and 6 having progressive disease on post-transplant PET/CT. In terms of outcome, the 3-year PFS for the PET positive group was 42% (5/12). Of those, 2 (17%) had durable 5-year PFS with treatment after transplant while the other 10 (83%) eventually died of their disease. The 3-year PFS rate in the PET negative group was 88% (23/26) (95% CI: 70 - 98%) and 42% (5/12) (95% CI: 15 - 72%%) for PET positive group. The difference in the 3-year PFS in the PET negative group is significantly larger than that of the PET negative group (p

Description: BACKGROUND: ABVD with or without radiation is standard therapy for limited stage HL, but carries risks of bleomycin-lung injury and radiation toxicity. Brentuximab vedotin (BV) is an anti-CD30 antibody drug conjugate which is highly active in relapsed classical HL. We previously combined BV with AVD in limited stage non-bulky classical HL which resulted in a high CR rate, but at the cost of increased neutropenia, neutropenic fever, and neuropathy, likely related to the overlapping toxicity profile with vinblastine. Similar toxicity findings were also observed with BV-AVD in advanced stage classical Hodgkin lymphoma. We therefore evaluated BV plus AD (BV-AD) without radiation therapy for non-bulky stage I-II classical HL with the goal of reducing toxicity and maintaining high rates of inducing CR. METHODS: This is a multicenter single arm open label phase 2 study. Patients received BV 1.2 mg/kg plus standard dose adriamycin and dacarbazine on days 1 and 15 of each 28 day cycle. GCSF prophylaxis was not included. Patients received 4 or 6 cycles of BV-AD based on the results of an interim PETCT scan performed following cycle 2. PET negativity was defined as Deauville scores 1-3. Patients in CR on interim PETCT received 4 total cycles of therapy; patients in PR completed 6 cycles. The primary endpoint is complete response rate (CRR) at end of treatment. A sample size of 34 was required to detect an end of treatment CRR of 95% with 91% power and alpha error of 0.09. RESULTS: 34 patients were enrolled. Median age is 36 (range 18-63). Stage is IA (3), IB (1), IIA (29) and IIB (1). Risk is classified per the GHSG criteria as early unfavorable in 47%, and favorable in 53%. The interim CR rate is 94%. Accordingly, 32 interim PET negative patients (94%) received 4 total cycles of therapy, and 2 interim PET positive patients (6%) received 6 total cycles of therapy. No patients received consolidative radiation therapy, per protocol. The primary endpoint of end of treatment CR rate is 100%. At a median follow-up of 15 months, the FFS, PFS and OS are all 100%. The most common adverse events of any grade are nausea (79%), peripheral sensory neuropathy (56%), fatigue (50%), constipation (38%), alopecia (35%) and neutropenia (24%). Most toxicities were low grade, with only 15% of subjects experiencing any grade 3 toxicity, and there were no grade 4 or 5 toxicities. Specifically, 2 patients had grade 3 neutropenia, and 1 patient each had grade 3 nausea/vomiting, pneumonia and thromboembolic event. Peripheral sensory neuropathy was grade 1 in 17 patients, and grade 2 in 2 patients. There were no cases of neutropenic fever. CONCLUSIONS: BV-AD for 4-6 cycles induces high interim and end of treatment CR rates of 94% and 100%, respectively, allowing 4 total cycles of therapy in most patients. The PFS, FFS and OS are all 100% at last follow up. Toxicity appears mild and notable for a low incidence of neutropenia, alopecia, and moderate peripheral neuropathy. This promising regimen avoids bleomycin, vinblastine, radiation and primary GCSF prophylaxis with resultant low toxicity and preserved high efficacy rates in patients with early favorable and early unfavorable non-bulky limited stage classical Hodgkin lymphoma. Follow up for this trial is ongoing. Figure. Figure. Disclosures Abramson: Merck: Consultancy; Seattle Genetics: Consultancy; Karyopharm: Consultancy; Verastem: Consultancy; Amgen: Consultancy; Humanigen: Consultancy; Juno Therapeutics: Consultancy; Gilead: Consultancy; Novartis: Consultancy; Bayer: Consultancy; Celgene: Consultancy. Sokol:Mallinckrodt Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy; Spectrum Pharmaceuticals: Consultancy. Jacobsen:Merck: Consultancy; Seattle Genetics: Consultancy. LaCasce:Seattle Genetics: Consultancy, Honoraria; Research to Practice: Speakers Bureau; Humanigen: Consultancy, Honoraria; Bristol-Myers Squibb: Other: Data safety and monitoring board.

Description: Background: Administration of recombinant human thrombopoietin (rhTPO) with G-CSF for stem cell mobilization is associated with high CD34+ stem cell yield, rapid neutrophil recovery following autologus transplantation (ASCT), and decreased red blood cell (rbc) and platelet (plt) transfusions (Solomo, G. et al. Blood 1999). However, clinical development of rhTPO was complicated by the formation of neutralizing anti-TPO antibodies (Li, J. et al. Blood 2001), prompting discontinuation of further clinical development of recombinant TPO. Eltrombopag (Elt) is an orally bioavailable small molecule thrombopoietin receptor (TPO-R) agonist approved by the FDA for treatment of chronic immune thrombocytopenic purpura (ITP). In vitro studies have demonstrated that Elt promotes megakaryocyte proliferation and differentiation of CD34+ bone marrow progenitor cells (Erickson-Miller CL Stem Cells 2009), suggesting that Elt might be a surrogate for rhTPO for stem cell mobilization. In this pilot trial, we evaluated the combination of Elt plus standard G-CSF and cyclophosphamide (C) for stem cell mobilization in patients (pts) with multiple myeloma (MM), a disease for which ASCT remains a standard of care (Blade et al. Blood 2010). Methods: Primary objectives included determination of the median number of CD34+ cells/kg mobilized and the maximum tolerated dose (MTD) of Elt. Pts had MM that was stable or responsive to at least two cycles of chemotherapy with plans for stem cell mobilization and ASCT. Four pts were to be enrolled in each of four dose escalation arms in which they received 0 (Arm D), 50 (Arm A), 100 (Arm B), or 150 mg (Arm C) of eltrombopag in combination with standard C + G-CSF. Adverse events (AEs) were graded by NCI-CTCAE v4. Results: 17 pts have been screened and enrolled to date. Two patients withdrew consent prior to receiving Elt and were excluded from statistical analysis. 15 patients have completed participation in the study to date and two patients remain to be enrolled in Arm C. The first subject in Arm A experienced delayed engraftment that was determined to be unrelated to ELT; rather, the event was attributed to administration of a one-time high dose of corticosteroid for management of a severe hypersensitivity reaction to DMSO that occurred during stem cell infusion. A second subject in Arm A had undergone mobilization with Elt prior to the previously described delayed engraftment event, and to ensure safety underwent a second mobilization with G-CSF and plerixafor. During ASCT, this patient received cells from the second mobilization procedure. While neither event met criteria for a dose-limiting toxicity, the protocol was amended such that three additional patients enrolled in Arm A underwent two rounds of mobilization - the first with Elt plus C and G-CSF and a second with G-CSF plus plerixafor - and received as part of ASCT cells mobilized with Elt. Each of these patients engrafted successfully. The median number of CD34+ cells/kg collected during the first collection day of apheresis in Arms D, A, B, and C was 8.0, 11.0, 15.3, and 26.4. The median total number of CD34+ stem cells collected following mobilization with Elt plus C and G-CSF in Arms D, A, B, and C was 13.2, 12.7, 15.4, and 26.4. The percentage of patients in Arms D, A, B, and C who achieved a target collection of 8 x 10^6 CD34+ stem cells in one collection day was 50, 60, 75, and 100%. There have been no severe adverse events related to Elt . Conclusions: Administration of Elt in combination with C plus G-CSF for stem cell mobilization in pts with MM undergoing ASCT was safe and well tolerated, with no DLTs or severe AEs attributable to Elt. The small size of this pilot study precludes formal statistical comparison of outcomes across treatment Arms, but there appears to be a trend toward increase in yield of CD34+ cells and decrease in apheresis procedures required with increasing doses of Elt. Disclosures Richardson: Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees.