Somlo, George

Lineage-specific growth factors mobilize peripheral blood progenitor cells (PBPC) and accelerate hematopoietic recovery after high-dose chemotherapy. Recombinant human thrombopoietin (rhTPO) may further increase the progenitor-cell content and regenerating potential of PBPC products. We evaluated the safety and activity of rhTPO as a PBPC mobilizer in combination with granulocyte colony-stimulating factor (G-CSF) in 29 breast cancer patients treated with high-dose chemotherapy followed by PBPC reinfusion. Initially, patients received escalating single doses of rhTPO intravenously (IV) at 0.6, 1.2, or 2.4 μg/kg, on day 1. Subsequent patients received rhTPO 0.6 or 0.3 μg/kg on days −3, −1, and 1, or 0.6 μg/kg on days −1 and 1. G-CSF, 5 μg/kg IV or subcutaneously (SC) twice daily, was started on day 3 and continued through aphereses. Twenty comparable, concurrently and identically treated patients (who were eligible and would have been treated on protocol but for the lack of study opening) mobilized with G-CSF alone served as comparisons. CD34+ cell yields were substantially higher with the first apheresis following rhTPO and G-CSF versus G-CSF alone: 4.1 × 106/kg (range, 1.3 to 17.6) versus 0.8 × 106/ kg (range, 0.3 to 4.2), P = .0003. The targeted minimum yield of 3 × 106CD34+ cells/kg was procured following a single apheresis procedure in 61% of the rhTPO and G-CSF–mobilized group versus 10% of G-CSF–mobilized patients (P = .001). In rhTPO and G-CSF mobilized patients, granulocyte (day 8 v 9, P= .0001) and platelet recovery (day 9 v 10, P= .07) were accelerated, and fewer erythrocyte (3 v 4,P = .02) and platelet (4 v 5, P = .02) transfusions were needed compared with G-CSF–mobilized patients. Peripheral blood platelet counts, following rhTPO and G-CSF, were increased by greater than 100% and the platelet content of PBPC products by 60% to 110% on the first and second days of aphereses (P < .0001) with the greatest effect seen with repeated dosing of rhTPO at 0.6 μg/kg. rhTPO is safe and well tolerated as a mobilizing agent before PBPC collection. Mobilization with rhTPO and G-CSF, in comparison to a comparable, nonrandomized G-CSF–mobilized group of patients, decreases the number of apheresis procedures required, may accelerate hematopoietic recovery, and may reduce the number of transfusions required following high-dose chemotherapy for breast cancer.

Abstract Background: BT062 (Biotest AG, Dreieich, Germany) is an antibody-drug conjugate (ADC) comprising a CD138-binding chimerized antibody and the cytotoxic maytansinoid, DM4. It is designed to target and kill CD138-positive cancer cells. CD138 (Syndecan-1) is highly expressed on a number of solid tumors and hematological malignancies and is one of the most reliable markers for multiple myeloma (MM) cells. BT062 was previously evaluated as a monotherapy in patients with heavily pretreated relapsed/refractory MM and found to have an acceptable tolerability profile with preliminary evidence of activity (Heffner et al, Blood. 2012; 120: Abstract 4042). Phase I/IIa testing was initiated with BT062 in combination with lenalidomide (Len) and low-dose dexamethasone (dex). The combination was well tolerated at BT062 doses up to 100 mg/m², defined to be the recommended Phase 2 dose (RPTD), and induced meaningful responses, including in patients previously treated with both Len and bortezomib (Bort) (Kelly et al, Blood. 2014; 124: Abstract 4736). Based on these promising results, further investigation of BT062 in combination with pomalidomide (Pom) and dex was initiated in patients with prior Len and Bort exposure, a patient population known to have a poor outcome. Objectives: To evaluate the safety and activity of BT062 (on days 1, 8, and 15 in a 4-week cycle) used in combination with dex (20-40 mg on days 1, 8, 15, and 22) and Len (25 mg, daily on days 1-21) or Pom (4 mg, daily on days 1-21) in patients with relapsed/refractory MM. Methods: This is a prospective, open label, multicenter Phase I/IIa study. The RPTD of BT062 in combination with Len/dex was defined to be 100 mg/m², and 38 patients were treated with BT062/Len/dex at the BT062 RPTD. An additional 17 patients were treated with BT062/Pom/dex at the BT062 RPTD. Patients aged ≥18 years with relapsed/refractory MM were eligible to participate. Prior treatment with Len, Pom, and/or dexamethasone (any dose) was allowed. To qualify for treatment with BT062/Len/dex at the BT062 RPTD, patients must have received at least one but no more than six prior therapies.To qualify for treatment with BT062/Pom/dex, patients must have received at least two prior therapies, including both Len and Bort, and progressed on or within 60 days of completion of their last therapy, with no limit on number of prior therapies. Patients with clinical response (or no evidence of disease progression) without unacceptable toxicities were eligible to receive additional treatment cycles. Toxicities were assessed by CTCAE v4. Clinical response was assessed by the investigator according to International Myeloma Working Group criteria. Results: Sixty-four patients have received BT062 in combination with dex and Len or Pom in this ongoing study. The combinations have been generally well tolerated, with approximately 90% of adverse events (AEs) reported CTC grade 1 or 2. The most common AEs reported are diarrhea, fatigue, and nausea. Forty-seven patients have received BT062 with Len/Dex (3 at 80 mg/m², 38 at 100 mg/m², 6 at 120 mg/m²), with 8 patients still on treatment. Among these 47 patients, median progression-free survival (PFS) was 16.4 months. Forty-three patients completed at least two treatment cycles and were evaluable for response. Of these patients 33 achieved a partial response (PR) or better, with an overall response rate (ORR) of 77% and a median duration of response (DOR) of 21.0 months. Thirteen of the evaluable BT062/Len/dex-treated patients had prior exposure to both Len and Bort and progressed on or within 60 days of their last therapy. ORR was 54% among these patients, including 1 complete response (CR), 4 very good partial responses (VGPR) and 2 PRs. Seventeen patients were treated with BT062/Pom/dex, all had prior exposure to both Len and Bort and progressed on or within 60 days of their last therapy. ORR was 79%, with 4 VGPR and 7 PR among the 14 patients evaluable for efficacy. Median PFS has not been reached after 7.5 months median follow up, with 7 patients still on treatment. Updated safety and activity data will be presented. Conclusion: BT062 has been found to be well tolerated when used in combination with Len/dex or Pom/dex, with encouraging activity even in patients with Len- and Bort-pretreated disease progressing on or within 60 days of completion of their last therapy. Disclosures Kelly: Novartis: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Siegel:Novartis: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Merck: Honoraria. Somlo:Millennium: Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Heffner:Millennium: Research Funding; AbbVie: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding. Madan:Onyx: Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Celgene: Speakers Bureau. Lonial:Celgene: Consultancy; Celgene: Consultancy; BMS: Consultancy; Onyx: Consultancy; Millenium: Consultancy; Novartis: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Onyx: Consultancy; Janssen: Consultancy; Merck: Consultancy; BMS: Consultancy. Barmaki-Rad:Biotest AG: Employment. Rühle:Biotest AG: Employment. Herrmann:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Celgene: Membership on an entity's Board of Directors or advisory committees; Oncoprep: Equity Ownership; Acetylon: Equity Ownership; Acetylon: Equity Ownership; Gilead: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Oncoprep: Equity Ownership; Millennuim: Membership on an entity's Board of Directors or advisory committees; Millennuim: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Equity Ownership; C4 Therapeutics: Equity Ownership; Bristol Myers Squibb: 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.

Abstract Triplet regimens combining an immunomodulatory agent, a proteasome inhibitor (PI), and a steroid are used to treat newly diagnosed and relapsed multiple myeloma (MM). Although ixazomib (Ix), an oral PI with single agent activity, can be combined with lenalidomide (LEN), patients (pts) with relapsed/refractory (R/R) MM are often LEN-refractory. Pomalidomide (POM) has single agent activity in LEN-refractory disease, and both POM and Ix also show activity in poor cytogenetic risk pts. Methods: Primary objectives: 1) determine the maximum tolerated dose (MTD) of Ix in combination with standard dose POM and dexamethasone (DEX), and 2) evaluate the anti-tumor activity of the triplet. The treatment regimen included two dose levels (3 mg and 4 mg) of Ix on days 1, 8, 15; POM 4 mg days 1-21; and DEX 40 mg days 1, 8, 15, 22, of a 28 day cycle. Eligibility: R/R MM after >1 prior therapy, LEN-refractory, and ≤ grade(gr) 1 peripheral neuropathy (PN). Pts were treated until progression or unacceptable toxicity. Design: Phase I study utilizing a standard 3+3 design; dose limiting toxicities (DLTs) defined during cycle 1. Results: 32 pts treated, 31 evaluable for toxicity and response. Pts received a median 4 cycles (range 1-13); median follow-up is 5.5 months (range 1.8-21.1). Six pts treated on DL1, 25 treated on DL2, the MTD/Phase II dose (P2D). Median age: 62 years (range 38-84); median time from diagnosis: 3.7 years (range 1.0-8.9); median number prior therapies: 3 (range 1-5); prior transplant: n = 23 (74%); double (LEN/Bortezomib[BOR]) or triple (LEN/BOR/Carfilzomib[CFZ]) refractory: 19 (61%). Phase I: DL1 expanded to n=6 after 1/3 pts experienced DLT (gr3 lung infection); no further DLT seen on DL 1 or 2. Adverse events (AEs) related to POM and/or Ix: ANC decrease Gr1/2 n=11 (35%), Gr3/4 n=10 (32%), platelet decrease Gr1/2 n=9 (29%), lymphocyte decrease Gr1/2 n=8 (26%), Gr3/4 n=11 (35%), PN Gr1/2 n=9 (29%), no Gr3/4. Response: Phase I and II, n=31 pts treated. ORR: 45% (6 VGPR, 8 PR); Clinical Benefit Rate (CBR): 81% (6 VGPR, 8 PR, 3 MR, 8 SD). In the pts with high risk cytogenetics (7[23%] 1q, 3[10%] 17p, 2[6%] t(4;14)) an ORR of 58% (3 VGPR, 4 PR) was seen, and the CBR was 83%. In the double or triple refractory pts, an ORR of 26% and CBR of 79% (1 VGPR, 4 PR, 3 MR, 7 SD) were observed. Conclusions: Ix/POM/DEX is a well-tolerated oral combination therapy, and responses were seen even at DL1 and in high risk patients, including those with poor-risk cytogenetics or advanced refractory disease. Disclosures Kapoor: Celgene: Research Funding; Amgen: Research Funding; Takeda: Research Funding. Kumar:Millennium: Consultancy, Research Funding; AbbVie: Research Funding; Glycomimetics: Consultancy; Sanofi: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; BMS: Consultancy; Kesios: Consultancy; Onyx: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding. Lonial:Novartis: Consultancy; BMS: Consultancy; Janssen: Consultancy; Merck: Consultancy; Celgene: Consultancy; Onyx: Consultancy; Novartis: Consultancy; BMS: Consultancy; Celgene: Consultancy; Millenium: Consultancy; Janssen: Consultancy; Onyx: Consultancy. Nathwani:Carevive Systems, Inc.: Research Funding. Forman:Mustang Therpapeutics: Other: Construct licensed by City of Hope. Berdeja:Abbvie, Acetylon, Amgen, Bluebird, BMS, Calithera, Celgene, Constellation, Curis, Epizyme, Janssen, Karyopharm, Kesios, Novartis, Onyx, Takeda, Tragara: Research Funding.

Abstract Background: BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate (ADC), comprising the anti-CD138 chimerized MAb (nBT062) and the maytansinoid DM4 as a cytotoxic agent. It is designed to bind to CD138 on cancer cells, and then release DM4 after internalization to cause cell death. CD138 (Syndecan-1) is highly overexpressed on various solid tumors and in hematological malignancies, and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. BT062 was investigated as a single agent and found to have an acceptable tolerability profile and evidence of activity in patients with heavily pretreated relapsed and/or refractory MM (1). Preclinical studies showed enhanced anti-MM activity when BT062 was combined with lenalidomide and dexamethasone (Len/Dex). Based on these data, a Phase I/IIa study in MM was initiated to evaluate the safety and efficacy of BT062 in combination with Len/Dex. Objectives: To determine the dose-limiting toxicities (DLTs), the maximum tolerated dose (MTD), the recommended phase II dose (RPTD), pharmacokinetics (PK), and anti-MM activity of increasing doses of BT062 (days 1, 8, and 15, every 4 weeks) used in combination with Len (25 mg, daily on days 1-21) and low dose Dex (40 mg on days 1, 8, 15, and 22) in patients with relapsed and/or refractory MM. Methods: This is a prospective, open label, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the RPTD cohort. Patients aged ≥18 years with relapsed and/or refractory MM who have failed at least one prior therapy were eligible to participate. Prior treatment with Len and/or Dex was allowed. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for additional treatment cycles. Patients were enrolled in cohorts of at least 3 at each dose level; DLT in the first cycle triggered cohort expansion. Toxicities were assessed by CTCAE v4 and clinical response was assessed according to International Myeloma Working Group criteria. Results: The maximum administered dose (MAD) was 120 mg/m². Two of six patients treated at this dose had a DLT: mucosal inflammation (CTC grade 3) and anemia (CTC grade 3). The MTD was defined as 100 mg/m² and selected as RPTD. Additional patients are being treated at this RPTD to further evaluate safety and efficacy. Enrollment into the study is ongoing. As of July 2014, a total of 45 patients had received BT062 at dose levels of 80 mg/m² (N=3), 100 mg/m² (N=36) or 120 mg/m² (N=6). Fifteen patients discontinued study treatment: 5 for disease progression, 7 for adverse events, 1 died (not treatment related) and 2 for withdrawal of consent. The other 30 patients remain on treatment. The median treatment duration was 123 days (range 1–597). The median number of prior therapies was 3 (range 1–11). 68% of patients had prior exposure to both Len and bortezomib, 73% of patients had prior Len exposure, and 30% were Len-refractory. According to preliminary data from this ongoing study, about 89% of reported Adverse Events (AEs) were CTC grade 1 or 2. The most common reported AEs were diarrhea, fatigue, nausea, and hypokalemia. Amongst the 36 patients across all dose levels currently evaluable for efficacy, the overall response rate (ORR) is 78%; including 1 stringent complete response, 2 complete responses, 10 very good partial responses, and 15 partial responses. Two patients achieved a minor response and 6 patients disease stabilization, resulting in a clinical benefit in 100% of the evaluable patients. The ORR was 83% among the 30 evaluable patients receiving the RPTD. Interestingly, the ORR was 70% among the 23 patients with prior exposure to Len and bortezomib, and among 10 patients refractory to prior treatment with Len. Conclusion: Preliminary data from this ongoing study indicate that BT062 is well tolerated in combination with Len/Dex at dose levels that induce responses in patients with relapsed and/or refractory multiple myeloma, including patients with prior exposure to both Len and bortezomib and patients refractory to prior treatment with Len. Updated results on safety and efficacy will be presented. References Heffner et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Given Weekly for 3 Weeks in Each 4 Week Cycle: Safety and Further Evidence of Clinical Activity. Blood. 2012; 120: Abstract 4042. Disclosures Kelly: Celgene: Speakers Bureau. Heffner:Amgen: Honoraria, Research Funding; Biotest: Research Funding; Dana Farber CI: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Idera: Research Funding; Janssen: Research Funding; Pfizer: Research Funding; Pharmacyclics: Honoraria, Research Funding; Onyx: Research Funding; Spectrum: Research Funding; Talon Therapeutics: Research Funding. Somlo:Millennium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene: Honoraria, Speakers Bureau; Onyx: Honoraria, Speakers Bureau; Millennium: Honoraria, Speakers Bureau. Munshi:Celgene: Consultancy; Onyx: Consultancy; Janssen: Consultancy; Sanofi-Aventis: Consultancy; Ocopep: Consultancy, Equity Ownership, Patents & Royalties. Jagannath:Celgene: Consultancy; Millennium: Consultancy; Sanofi: Consultancy. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Ailawadhi:Millennium: Consultancy, Honoraria. Barmaki-Rad:Biotest AG: Employment. Chavan:Biotest Pharmaceuticals: Employment. Patel:Biotest Pharmaceuticals: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncopep: Equity Ownership; Acetylon: Equity Ownership.

Abstract Lineage-specific growth factors mobilize peripheral blood progenitor cells (PBPC) and accelerate hematopoietic recovery after high-dose chemotherapy. Recombinant human thrombopoietin (rhTPO) may further increase the progenitor-cell content and regenerating potential of PBPC products. We evaluated the safety and activity of rhTPO as a PBPC mobilizer in combination with granulocyte colony-stimulating factor (G-CSF) in 29 breast cancer patients treated with high-dose chemotherapy followed by PBPC reinfusion. Initially, patients received escalating single doses of rhTPO intravenously (IV) at 0.6, 1.2, or 2.4 μg/kg, on day 1. Subsequent patients received rhTPO 0.6 or 0.3 μg/kg on days −3, −1, and 1, or 0.6 μg/kg on days −1 and 1. G-CSF, 5 μg/kg IV or subcutaneously (SC) twice daily, was started on day 3 and continued through aphereses. Twenty comparable, concurrently and identically treated patients (who were eligible and would have been treated on protocol but for the lack of study opening) mobilized with G-CSF alone served as comparisons. CD34+ cell yields were substantially higher with the first apheresis following rhTPO and G-CSF versus G-CSF alone: 4.1 × 106/kg (range, 1.3 to 17.6) versus 0.8 × 106/ kg (range, 0.3 to 4.2), P = .0003. The targeted minimum yield of 3 × 106CD34+ cells/kg was procured following a single apheresis procedure in 61% of the rhTPO and G-CSF–mobilized group versus 10% of G-CSF–mobilized patients (P = .001). In rhTPO and G-CSF mobilized patients, granulocyte (day 8 v 9, P= .0001) and platelet recovery (day 9 v 10, P= .07) were accelerated, and fewer erythrocyte (3 v 4,P = .02) and platelet (4 v 5, P = .02) transfusions were needed compared with G-CSF–mobilized patients. Peripheral blood platelet counts, following rhTPO and G-CSF, were increased by greater than 100% and the platelet content of PBPC products by 60% to 110% on the first and second days of aphereses (P &lt; .0001) with the greatest effect seen with repeated dosing of rhTPO at 0.6 μg/kg. rhTPO is safe and well tolerated as a mobilizing agent before PBPC collection. Mobilization with rhTPO and G-CSF, in comparison to a comparable, nonrandomized G-CSF–mobilized group of patients, decreases the number of apheresis procedures required, may accelerate hematopoietic recovery, and may reduce the number of transfusions required following high-dose chemotherapy for breast cancer.

591 Background: Both Cb and Bev demonstrate activity when combined with standard chemotherapy in TNBC. CALGB 40603 is a 2x2 randomized trial that previously demonstrated that adding Cb to NACT significantly increased pathologic complete responses in the breast/axilla (pCR), while adding Bev did not (Sikov, JCO 2015). Here we report 5-year LTOs and assess factors that influenced them. Methods: 443 patients with clinical stage II-III previously untreated TNBC received 12 weeks of paclitaxel (wP) +/- Cb then dose-dense AC, +/- Bev before surgery. The primary endpoint was pCR. Analyses of LTOs (event-free survival (EFS), distant recurrence-free interval (DRFI) and overall survival (OS)), impact of residual cancer burden and other variables were secondary. Results: Median follow-up was 5.7 years (y); 5y EFS was 70.9% (95% CI; 66.7%-75.4%), DRFI 76.3% (72.3%-80.5%) and OS 76.9% (72.9%-81.2%). Pretreatment clinical stage and achieving pCR correlated with LTOs, while age, race, subtype (basal-like vs. not) and tumor grade did not. Among pCR 5y EFS was 86.4% vs. 57.5% for non-pCR (HR 0.28, 0.19-0.43), OS was 88.7% vs 66.5% (HR = 0.28, 0.17-0.44). This relationship was similar in all trial arms. Any residual disease conferred poorer outcome; compared with pCR/Residual Cancer Burden (RCB) 0, EFS HRs were 2.29 (1.32-3.97), 3.01 (1.90-4.74), and 9.67 (5.66-16.51) for RCBI, II and III, respectively. There were no improvements in LTOs with Cb (EFS HR 0.99, 0.70-1.40) or Bev (EFS HR 0.91, 0.64-1.29). In an exploratory analysis, receipt of ≥11 doses of wP was associated with better EFS (HR 1.92, 1.33-2.77); this was particularly notable in Cb-treated arms. Conclusions: As expected, regardless of treatment arm pCR was associated with markedly better LTOs, and pts with any residual disease had significantly worse outcomes. The addition of Cb or Bev to standard NACT for TNBC did not improve LTOs in this trial, although it should be noted that the trial was not powered for this endpoint. Omission of chemotherapy doses may result in poorer outcomes, especially among Cb-treated pts, which may warrant further evaluation. Support: U10CA180821; U10CA180882; Genentech; https://acknowledgments.alliancefound.org ; NCT00861705 Clinical trial information: NCT00861705.