ALBERT

Description: Abstract 1862 Poster Board I-887 Background: Biotest AG (Dreieich, Germany) is developing the immunoconjugate BT062, which comprises the anti-CD138 chimerized MAb (nBT062) and the cytotoxic agent maytansinoid (DM4). Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4. At present, CD138 represents one of the most reliable target antigens for identification of multiple myeloma (MM) cells and has been reported to be a highly sensitive and specific diagnostic marker of MM. Preclinical investigations demonstrated significant in vitro and in vivo anti-MM activity of BT062, providing the rationale for the conduct of clinical trials (Ikeda et al., 2009). Objectives: To determine the maximum tolerated dose (MTD), the dose-limiting toxicities (DLTs), pharmacokinetics (PK) and anti-MM activity of increasing doses of BT062 on a repeated single dose schedule once every three weeks in relapsed or relapsed/refractory MM. Clinical response was assessed as per the international working group criteria (Durie et al., 2006). Methods: This is a prospective, open label, dose-escalation multicenter study. Patients aged ≥ 18 years with relapsed or relapsed/refractory MM who have failed previous treatments including an immunomodulating agent and a proteasome inhibitor were eligible to participate. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for further treatment cycles. Patients are enrolled in cohorts of 3 at each dose level, with DLT in the first cycle triggering cohort expansion. Results: To date 20 patients have been treated with BT062 at 7 dose levels ranging from 10 mg/m2 to 200 mg/m2. Maximum administered dose has not been defined to date with continued enrollment at 200 mg/m2 dose. None of the patients treated experienced serious hypersensitivity reactions or humoral responses (HAHA) against BT062. The most frequently reported adverse events to date cover primarily events expected for the underlying disease. Nevertheless, a few adverse events have also been observed involving skin and mucosa (tissues of epithelial origin with CD138 expressing cells). No grade 4 toxicity has been reported. Preliminary PK results indicate an unusual rapid clearance from plasma in the early elimination phase, followed by a generally normal terminal elimination phase at dose levels up to 120 mg/m2, whereas a more typical clearance profile was observed for all 3 patients at the 160 mg/m2 dose. Interestingly, even in phase I study decreased urine M-Protein or serum FLC levels have been observed in 2 patients. One of these patients showed a decrease in urine M-Protein by more than 50% after administration of 8 repeated low doses. At a high dose level another patient without detectable M-Protein levels, showed a decrease of serum FLC by more than 50% after having received the second dose of BT062. Furthermore, evidence of clinical benefit has been observed in at least 6 patients with early stabilization of M-protein levels (and light-chain burden) in serum and /or urine. Conclusion: Development of a monoclonal antibody in MM remains an important therapeutic option and BT062 is an exciting possibility. Preliminary data from this phase I study, demonstrate an acceptable toxicity profile of BT062 in the clinics. Even in phase I study, evidence of clinical activity is observed. These encouraging results and the unique PK observed support investigation of a more frequent dosing regimen for optimizing anti-MM responses. Updated data on safety, PK and efficacy of BT062 from this clinical trial will be presented at the meeting. Disclosures: Jagannath: Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Avigan:Genzyme: Consultancy, Research Funding; Celgene: Research Funding. Lutz:Immunogen, Inc.: Employment. Haeder:Biotest AG: Employment. Ruehle:Biotest AG: Employment. Uherek:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Munshi:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Anderson:Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Biotest AG: Consultancy, Research Funding.

Description: Abstract 3008 Background: BT062 represents a CD138 specific antibody-drug conjugate comprising a chimerized anti-CD138 antibody conjugated to maytansinoid (DM4), an inhibitor of tubulin polymerization. CD138 (syndecan-1) which is highly upregulated on neoplastic plasma cells, is currently used as a standard identification marker for multiple myeloma (MM) and provides therefore a promising target for therapeutic intervention in MM. We have previously reported that BT062 exerts high selective in vitro and in vivo cytotoxic activity against CD138 positive MM cells (Ikeda et al., Clin Cancer Res. 2009; 15(12)). Based on these results, a Phase I clinical trial has been conducted in relapsed/refractory MM patients, which demonstrated an acceptable toxicity profile after repeated administration of single doses up to 160 mg/m2, as well as first signs of clinical activity in heavily pretreated patients (Chanan-Khan et al., ASH 2009). Here, we investigated the anti-myeloma efficacy of BT062 when combined with clinically approved myeloma drugs in vitro and in experimental animals in vivo. Methods and Results: In vitro drug combination studies on different myeloma cell lines indicated that BT062 exerts synergistic cytotoxic activity when combined for example with lenalidomide on RPMI8226 myeloma cells. None of the myeloma drug combinations with BT062 resulted in a strong antagonistic effect. Lenalidomide and bortezomib, representing novel established anti-myeloma drugs, were further tested for combination with BT062 in SCID mice bearing MOLP-8 MM xenografts. A single intravenous injection of BT062 was active against these tumors (400 μg/kg: T/C = 7%, Log cell kill (LCK) = 2.7) without signs of toxicity (no body weight loss). Monotherapy of bortezomib (1 mg/kg, twice weekly for 2 weeks) was inactive against the MOLP-8 xenografts. However, when combined with BT062, a superior anti-tumor effect compared to BT062 monotherapy was observed: Single injection of BT062 at different concentrations (100 μg/kg, 200 μg/kg, 400 μg/kg) followed by i.v. administration of bortezomib (1 mg/kg, twice weekly for 2 weeks) resulted in a dose dependent inhibition of tumor cell growth (at 200 μg/kg: LCK = 2.0; T/C = 7%, at 400 μg/kg LCK = 3.2; T/C = 7%). No increased in toxicity have been observed in the combination treatment compared to each monotherapy. BT062 was further evaluated for combination with lenalidomide which was administered intraperitoneally, daily for 5 days (2 weeks in total): BT062 administered alone at concentrations of 400 μg/kg was highly active against the MOLP-8 tumors reflected by a LCK of 2.5 (T/C = 13%). A lower anti-tumor effect has been observed by lenalidomide monotherapy (LCK = 0.8, T/C = 38%). Combination of both drugs demonstrated superior anti-tumor activity compared to each monotherapy (e.g. 400 μg/kg BT062 + lenalidomide: LCK = 3.5; T/C = 8%). Remarkably, neither body weight loss nor symptoms of illness have been observed confirming that this combination is also well tolerated. Conclusion: These data demonstrate that BT062 is not only effective in MM monotherapy but represents further a promising candidate for combination with currently used anti-MM drugs such as bortezomib or lenalidomide. No increased toxicities have been observed in all in vivo xenograft studies indicating that BT062 combined with other cytotoxic compounds might be well tolerated in MM therapy. Interestingly, although BT062 has been administered as a single dose, the anti-tumor effect in combination with either bortezomib or lenalidomide was significantly enhanced. These data provide a rationale to further investigate BT062 in clinical combination trials. Disclosures: Zuber: Biotest AG: Employment. Daelken:Biotest AG: Employment. Aigner:Biotest AG: Employment. Haeder:Biotest AG: Employment. Ab:ImmunoGen, Inc.: Employment. Whiteman:ImmunoGen, Inc.: Employment. Lutz:ImmunoGen, Inc.: Employment. Osterroth:Biotest AG: Employment. Uherek:Biotest AG: Employment.

Description: Background BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate, comprising the anti-CD138 chimerized MAb (nBT062) and the maytansinoid DM4 as cytotoxic agent. Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4, leading to target 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. Data from two studies investigating BT062 as single agent demonstrated an acceptable tolerability profile and evidence of clinical activity in patients with heavily pretreated relapsed and/or refractory MM (1, 2). 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) 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, dose-escalation, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the MTD or 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 As of July 2013, a total of 15 patients have received BT062 at dose levels of 80 mg/m2 (N=3), 100 mg/m2 (N=6) or 120 mg/m2 (N=6). Two patients at the highest dose level discontinued study due to toxicity (DLT), another patient withdrew consent. The other 12 patients remain on treatment; median duration 144 days (range 8–385). The median number of prior therapies was 4 (range 1–11), 87% of patients had prior Len exposure, and 50% were Len/Dex refractory. The maximum administered dose (MAD) has been reached at 120 mg/m2, with mucosal inflammation (CTC grade 3) as DLT in one, and anemia (CTC grade 3) in a second of the 6 patients treated at this dose level. About 85% of reported Adverse Events (AE) were of CTC grade 1 or 2. The most common reported AEs were fatigue, hypokalemia, and diarrhea. Amongst the 9 patients currently evaluable for efficacy, responses were observed across all dose levels with a overall response rate (ORR) of 78%; including 1 patient with complete response (120 mg/m2), 1 patient with very good partial response (80 mg/m2), and 5 patients with partial response (80 and 100 mg/m2). Two other patients achieved disease stabilization, resulting in a clinical benefit in 100% of the evaluated patients. Interestingly, partial response was observed in 3 patients refractory to prior treatment with Len/Dex. The MTD has been defined as 100 mg/m2 and is currently expanded to further evaluate the safety and efficacy of BT062 at the RPTD. 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 Len/Dex-refractory patients. Updated results on safety and efficacy will be presented. References 1. Jagannath et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Shows Clinical Activity in Patients with Relapsed or Relapsed/Refractory Multiple Myeloma. Blood. 2011; 118: Abstract 305. 2. 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: Somlo: Celgene: Research Funding, Speakers Bureau; NIH: Research Funding; Millennium: Speakers Bureau. Heffner:Genentech: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Biotest: Honoraria, Research Funding; Onyx: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding. Siegel:Millennium: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau. Zimmerman:Celgene: Honoraria; Millennium: Honoraria; Onyx: Honoraria. Jagannath:Millennium: Honoraria; Celgene: Honoraria. Munshi:Celgene: Consultancy; Novartis: Consultancy; Millennium: Consultancy. Lonial:Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Onyx: Consultancy. Ruehle:Biotest AG: Employment. Chavan:Biotest Pharmaceuticals: Employment. Patel:Biotest Pharmaceuticals: Employment. Rothenburger:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Gilead: Consultancy; Sanofi Aventis: Consultancy; Onyx: Consultancy; Celgene: Consultancy; Acetylon: Equity Ownership; Oncopep: Equity Ownership.

Description: 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.

Description: Abstract 305 Background: CD138 (Syndecan-1) is highly overexpressed in various solid tumors and hematological malignancies and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate, comprised of the anti-CD138 chimerized MAb (nBT062) and the cytotoxic agent DM4. Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4, leading to target cell death. We performed the first in man study (969) to investigate safety and efficacy of BT062 in MM. Objectives: To determine the maximum tolerated dose (MTD), the dose-limiting toxicities (DLTs), pharmacokinetics (PK) and anti-MM activity of increasing doses of BT062 on a repeated single dose schedule once every three weeks in patients with relapsed and/or refractory MM. Methods: This is a prospective, open label, dose-escalation, multicenter phase I study. Patients aged ≥18 years with relapsed or relapsed/refractory MM who have failed previous treatments including an immunomodulatory agent and a proteasome inhibitor were eligible to participate. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for further treatment cycles. Patients were enrolled in cohorts of 3 at each dose level, with DLT in the first cycle triggering cohort expansion. Toxicities were assessed by CTCAE v3 and clinical response was assessed according to the international myeloma working group criteria. Results: A total of 32 patients have been treated with BT062, receiving one of 7 dose levels ranging from 10 mg/m2 to 200 mg/m2. Maximum administered dose has been defined at 200 mg/m2, with mucositis as the dose limiting toxicity (CTC grade III in 2 of the 3 patients in this cohort). Thirteen of 32 patients have been treated in an expanded MTD-cohort at 160 mg/m2. The most frequently reported adverse events to date are mild to moderate and cover primarily events expected for the underlying disease and patient group. A few adverse events have also been observed involving skin and/or mucosa (tissues of epithelial origin with CD138 expressing cells), as well as the eye. CTC grade II/III toxicity involving skin and/or mucosa (e.g. mucositis, stomatitis, hand/foot syndrome) has been observed mainly at the dose levels 160 mg/m2 or higher. Adverse events involving the eye (e.g. blurred vision, dry eye) have also been reported mainly in patients at the dose levels 160 mg/m2 or higher, all restricted to CTC grade I/II. Among the 27 evaluable patients, 3 patients responded including 1 partial response and 2 minor responses, with one patient (minor response) remaining on treatment for more than a year. Stabilization of disease was noted in an additional 11 patients, receiving a median of 5 cycles of therapy (range of 4–10). Thus stable disease or better was noted in 52% of patients. Most patients came off study due to disease progression. Conclusion: Preliminary data from this study demonstrate an acceptable toxicity profile of BT062. Even in this phase I patient population, evidence of clinical activity was observed. Based on the favourable safety profile, the pharmacokinetic data and early signs of clinical activity, a Phase I/IIa study in MM (975) is initiated to further evaluate the safety and anti-MM efficacy of BT062 in a more frequent dosing regimen. To date 13 patients have been treated with BT062 on the intensified multi-dose regimen, receiving one of the first four dose levels. Updated results on safety, PK and anti-MM efficacy of BT062 will be presented. Disclosures: Jagannath: Celgene: Honoraria; Millennium/Takeda Pharma: Honoraria; J&J Family: Honoraria; Onyx: Honoraria; Merck: Honoraria. Heffner:Millennium: Research Funding. Avigan:Genzyme: Consultancy, Research Funding; Celgene: Research Funding; Curetec: Research Funding. Lutz:ImmunoGen, Inc.: Employment. Engling:Biotest AG: Employment. Uherek:Biotest AG: Employment. Osterroth:Biotest AG: Employment. Ruehle:Biotest AG: Employment. Beelitz:Biotest Pharmaceuticals Corporation: Employment. Niemann:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Merck: Consultancy; Onyx: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Millennium Pharmaceuticals, Inc.: Consultancy; Bristol-Myers Squibb: Consultancy; Actelion: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Munshi:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Description: Abstract 4042 Background: CD138 (Syndecan-1) is highly overexpressed in various solid tumors and hematological malignancies, and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate, comprised of the anti-CD138 chimerized MAb (nBT062) and the cytotoxic agent DM4. Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4, leading to target cell death. Data from the first in human study (969) of BT062 demonstrated an acceptable toxicity profile and evidence of clinical activity in heavily pretreated relapsed and/or refractory MM patients(1). Based on these data, a Phase I/IIa study in MM (975) was initiated to further evaluate the safety and efficacy of BT062 when given more frequently. Objectives: To determine the maximum tolerated dose (MTD), the dose-limiting toxicities (DLTs), pharmacokinetics (PK), and anti-MM activity of increasing doses of BT062, when administered on a repeated, multiple dose schedule (Days 1, 8, and 15, every 4 weeks) in patients with relapsed and/or refractory MM. Methods: This is a prospective, open label, dose-escalation, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the MTD or Recommended Phase II Dose (RPTD) cohort. Patients aged ≥18 years with relapsed or relapsed/refractory MM who have failed previous treatment, including an immunomodulatory agent and a proteasome inhibitor, were eligible to participate. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for further 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 the international myeloma working group criteria. Results: A total of 29 patients have been treated with BT062, receiving 1 of the first 8 dose levels ranging from 40 mg/m2 to 160 mg/m2. One out of 6 patients treated at 140 mg/m2 experienced a palmar-plantar erythrodysesthesia syndrome that was assessed as DLT (SAE, CTC grade 3). Dose was escalated to 160 mg/m2, and 1 of the 2 patients treated experienced an elevation of liver enzymes that was reported as DLT (non-serious, CTC grade 3). Maximum administered dose has not been reached and recruitment into the 160 mg/m2 cohort is ongoing. About 90% of the reported Adverse Events (AE) are grades 1–2. The most frequently reported AEs are anemia, diarrhea, and fatigue. Among the 23 patients evaluable for efficacy, 1 patient achieved a partial response (PR) and has been on study treatment for more than 1 year. Stable disease (SD) for at least 3 months was noted in an additional 11 patients, with median progression free survival of 112 (90–245) days. Thus disease control (PR + SD) was noted in more than 50% (12/23) of patients. The most common reason for discontinuation was disease progression. Preliminary pharmacokinetic results indicate rapid early clearance of BT062 from plasma consistent with rapid delivery and binding of BT062 to the MM cells. No significant accumulation of BT062 was noted, even after the end of the 2nd and 3rd infusions within a cycle. Conclusion: Preliminary data from this ongoing study indicate that BT062 is well tolerated even in this multiple dose schedule and provide further evidence of its clinical activity. Dose escalation is ongoing (now at 160 mg/m2) to define the MTD/RPTD, with cohort expansion then planned to further evaluate the safety and efficacy of BT062 at this dose. Based on the favorable safety profile, a Phase I/IIa study (983) has been initiated to evaluate the safety and efficacy of BT062 in combination with lenalidomide and dexamethasone. Disclosures: Heffner: Millennium: Research Funding. Jagannath:Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Zimmerman:Novartis: Consultancy; Millennium: Honoraria; Celgene: Honoraria. Lonial:Onyx: Consultancy; Bristol-Myers Squibb: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Millennium: Consultancy; Merck and Co: Consultancy. Lutz:ImmunoGen, Inc.: Employment. Czeloth:Biotest AG: Employment. Osterroth:Biotest AG: Employment. Ruehle:Biotest AG: Employment. Beelitz:Biotest Pharmaceuticals Corporation: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Celgene: Consultancy; Onyx: Consultancy; Merck: Consultancy; Bristol-Myers Squibb: Consultancy; Acetylon: Membership on an entity's Board of Directors or advisory committees; Oncopep: Membership on an entity's Board of Directors or advisory committees; Millennium Pharmaceuticals: Consultancy. Munshi:Oncopep: Patents & Royalties; Merck: Consultancy; Onyx: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

Description: Abstract 3060 Background: CD138 represents one of the most reliable target antigens for identification of multiple myeloma (MM) cells and has been reported to be a highly sensitive and specific diagnostic marker of MM. BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate, comprised of the anti-CD138 chimerized MAb (nBT062) and the cytotoxic agent DM4. Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4, leading to targeted cell death. Preclinical investigations demonstrated strong in vitro and in vivo anti-MM activity of BT062, providing the rationale for the conduct of clinical trials (Ikeda et al., 2009). Objectives: To determine the maximum tolerated dose (MTD), the dose-limiting toxicities (DLTs), pharmacokinetics (PK) and anti-MM activity of increasing doses of BT062 on a repeated single dose schedule once every three weeks in patients with relapsed and/or refractory MM. Toxicities were assessed by CTCAE v3 and clinical response was assessed according to the international working group criteria. Methods: This is a prospective, open label, dose-escalation multicenter study. Patients aged ≥ 18 years with relapsed or relapsed/refractory MM who have failed previous treatments including an immunomodulatory agent and a proteasome inhibitor were eligible to participate. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for further treatment cycles. Patients were enrolled in cohorts of 3 at each dose level, with DLT in the first cycle triggering cohort expansion. Results: A total of 32 patients have been treated with BT062, receiving one of 7 dose levels ranging from 10 mg/m2 to 200 mg/m2. Maximum administered dose has been defined at 200 mg/m2, with mucositis as the dose limiting toxicity (CTC grade III in 2 of the 3 patients in this cohort). Therefore, the MTD was defined at 160 mg/m2. Thirteen of 32 patients have been treated in an expanded MTD-cohort. No CTC grade 4 toxicity has been reported. The most frequently reported adverse events to date cover primarily events expected for the underlying disease and patient group. Most of the reported adverse events are CTC grade I to II. Nevertheless, a few adverse events have also been observed involving skin and/or mucosa (tissues of epithelial origin with CD138 expressing cells), as well as the eye. Severe events involving skin and/or mucosa (e.g. mucositis, hand/foot syndrome) have only been observed at the dose levels 160 mg/m2 or higher. Adverse events involving the eye (e.g. blurred vision, dry eye) have been reported in only 3 patients overall at the dose levels 160 mg/m2 or higher, all CTC grade I to II. At dose levels up to 120 mg/m2, preliminary PK results indicate an unusual rapid clearance from plasma in the early elimination phase, followed by a generally normal terminal elimination phase. A more typical clearance profile was observed for all patients at the 160 mg/m2 and 200 mg/m2 dose. To date, one patient showed a decrease in urine M-Protein by 〉50% after 8 repeated low doses of 20 mg/m2 each. At a high dose level of 160 mg/m2, another patient showed a 〉50% decrease of serum FLC after two doses of BT062. In total, stabilization of disease was noted in 13 patients. Patients with stable disease received a median of 5 cycles of therapy (range of 3–10). Most patients came off study due to disease progression. Conclusion: Preliminary data from this phase I study demonstrate an acceptable toxicity profile of BT062. Even in this phase I patient population, evidence of clinical activity was observed. Based on the favourable safety profile, the pharmacokinetic data and early signs of clinical activity, a Phase I/II study in MM is initiated to further evaluate the safety and anti-MM efficacy of BT062 in a more frequent dosing regimen. Updated results on safety, PK and efficacy of BT062 will be presented. Disclosures: Jagannath: Celgene: Honoraria; Millenium/Takeda Pharma: Honoraria; J&J Family: Honoraria; Onyx: Honoraria; Merck: Honoraria. Heffner:Millennium: Research Funding. Avigan:Genzyme: Consultancy, Research Funding; Celgene: Research Funding; Curetec: Research Funding. Lutz:ImmunoGen, Inc.: Employment. Uherek:Biotest AG: Employment. Osterroth:Biotest AG: Employment. Ruehle:Biotest AG: Employment. Haeder:Biotest AG: Employment. Niemann:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Munshi:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Anderson:Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Onyx: Consultancy; Merck: Consultancy; Bristol Myers Squibb: Consultancy; Acetylon: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.