Scott Koenig
Analyst · H.C. Wainwright
Thank you, Stephen. I will start with flotetuzumab, an investigational bispecific CD123 x CD3 DART molecule and our most recent product candidate to date in a registration study. Informed by discussions with the FDA, this trial will be a single-arm study in up to 200 AML patients whose disease is either refractory to induction treatment, which we refer to as primary induction failure or as relapsed early within 6 months after an initial response. The study will be conducted as an expansion of the ongoing Phase I/II study. The primary endpoint is response rate comprised of complete remission and complete remissions with partial hematological recovery or CRH. We plan to submit updated study data for presentation at a scientific conference in the fourth quarter of 2020. In June, research led by Dr. Sergio Rutella at the John van Geest Cancer Research Center in the U.K., was published in science translational medicine and describes an immunological signature related to interferon gamma gene expression in the tumor microenvironment. In patients with primary refractory or early relapsed AML, this gene signature appears to be predictive of resistance to chemotherapy, yet associated with response to flotetuzumab treatment. These data provide a molecular basis to understand why AML patients who are refractory to chemotherapy may be responsive to immunotherapy with flotetuzumab. Moving on to MGC018, our investigational antibody drug conjugate designed to deliver a DNA alkylating, duocarmycin cytotoxic payload to cells that express B7-H3. Initial dose escalation data for the ongoing Phase I study was very well received at the ASCO Virtual Annual Meeting. Of particular interest was the early evidence of clinical activity observed in patients with metastatic castration-resistant prostate cancer or MCRPC. Reductions in PSA levels of 50% or more were observed in 5 of 7 patients including 1 with substantial regression of bone disease. The safety profile of MGC018, which includes hematologic and skin toxicities as expected has been manageable. The patients with prostate cancer reported at ASCO were enrolled at a 2 mg/kg or 3 mg/kg dose cohorts. Since ASCO, we have completed the planned dose escalation up to 4 mg/kg and selected 3mg/kg as the recommended dose for expansion based on pharmacokinetic analysis. In the third quarter, we expect to begin dose expansion in patients with metastatic CRPC with a target enrollment of up to 40 patients. Next, I would like to turn to initial data related to MGD013, our investigational bispecific PD-1 x LAG-3 DART molecule, also presented at ASCO. In the ongoing Phase I dose expansion study, the data presented showed antitumor activity of MGD013 as monotherapy across several tumor types evaluated. Initial translational studies have indicated that response to MGD013 monotherapy was associated with LAG-3 expression and a gamma-interferon gene signature in tumor samples taken at baseline, a finding that we are investigating further. We have previously observed that LAG-3 expression on immune effector cells is enhanced by margetuximab, our investigational Fc-engineered monoclonal antibody targeting HER2. Therefore, we included an expansion cohort of patients with advanced HER2-positive tumors treated with a combination of MGD013 and margetuximab. Of the 14 evaluable patients treated with this combination, we observed confirmed and non-confirmed objective responses in 6 or 30 -- 43% of patients. In contrast to the monotherapy finding presented at ASCO, in the combination cohort, the majority of responders with baseline tumors were evaluated, were either negative 4 were expressed low levels of LAG-3 or PD-L1. Given this strong but early efficacy signal and acceptable safety profile, we are prioritizing the combination of MGD013 and margetuximab for further development. We are enrolling 3 subgroups of patients with HER2-positive tumors, one with gastric or gastroesophageal junction cancer, one with breast cancer, and finally, a basket of all other HER2-positive cancer types. We are initially targeting 30 patients in each group. We believe that combining Fc-engineering and checkpoint blockade has the potential to engage both innate and adaptive immune responses against a broad range of tumors with varied tumor microenvironments. With regard to margetuximab, the BLA for margetuximab in combination with chemotherapy as a treatment for patients with metastatic HER2-positive breast cancer, the PDUFA target action date of December 18, 2020. As previously announced, during the mid-cycle communication with the U.S. FDA, they notified us they no longer plan to hold an ODAC meeting to discuss the BLA. Beyond breast cancer, the Phase II/III MAHOGANY study is evaluating margetuximab and checkpoint blockade as a frontline treatment for advanced gastric and gastroesophageal junction cancer. Module A, the single-arm part of the MAHOGANY study of margetuximab and retifanlimab, an investigational anti-PD-1 antibody is enrolling, and we expect to submit initial data for presentation at a scientific conference in the first quarter of 2021. Module B, the randomized component of MAHOGANY, is currently planned to start the fourth quarter of 2020. Let me next discuss MGD019, our investigational bispecific PD-1 x CTLA-4 DART molecule. We are excited to have data from the Phase I dose escalation study of MGD019 selected for an oral presentation at the ESMO Virtual Congress in September. The study is ongoing in an all-comer population with advanced cancers. We have not restricted the study to tumor types that are known to respond to checkpoint inhibitors. Dose cohorts ranged from 0.03 to 10 mg/kg. Additional patients have been enrolled more recently at 3 mg/kg, 6 mg/kg and 10 mg/kg, dose levels of which we observed initial clinical activity. The data continues to mature with some patients early in their treatment course. By the time of the data cutoff date for the presentation at ESMO, we anticipate up to a total of 30 patients will be evaluable for response, having had at least 1 on treatment scan. Note that this number includes patients enrollment treated at all doses with approximately 18 enrolled at 3 mg/kg and above. Let me next turn to retifanlimab, previously known as MGA012, the investigational anti-PD-1 antibody that we license to Incyte. At ESMO, data are scheduled to be presented from Incyte's ongoing POD1UM-201 study of retifanlimab monotherapy in patients with Merkel cell carcinoma. Those data are in addition to the data expected in the second half of the year from POD1UM-202 Incyte's potentially registration enabled study in patients with anal cancer which is fully enrolled. Furthermore, we expect Incyte to initiate 2 Phase III studies in 2020, POD1UM-304 in patients with metastatic non-small cell lung cancer and POD1UM-303 in patients with anal cancer, both in combination with chemotherapy. In all, there are currently 6 registration-direct clinical studies ongoing or planned in 2020 by either MacroGenics or Incyte across a broad range of tumor types. Last but not least, we are pleased that our second antibody-drug conjugate is expected to enter clinical testing this year. We recently received FDA clearance of the Investigational New Drug, or IND, application for IMGC936, an ADC targeting ADAM9 that is being advanced under a co-development agreement with ImmunoGen. Under this 50-50 collaboration, ImmunoGen will be leading clinical development, and they expect to initiate a Phase I dose escalation study in patients with select advanced solid tumors in the fourth quarter of 2020. For background, ADAM9, a disintegrin and metalloproteinase domain containing protein 9 is a cell surface antigen that is overexpressed in very solid tumor types and has been shown to correlate with core prognosis in several cancers. This regulation of ADAM9 has been implicated in tumor progression and metastasis as well as pathological neovascularization. Anti–ADAM9 antibodies are efficiently internalized and degraded by ADAM9 expressing tumors, making it an attractive ADC target for delivering a cytotoxic payload. IMGC936 is comprised of a humanized antibody engineered by MacroGenics, conjugated in a site-specific manner to a DM21, a next-generation linker/payload designed by ImmunoGen. This molecule combines a maytansinoid microtubule-disrupting payload with a peptide linker that is designed to convey greater stability and bystander activity than other DM platforms. The drug antibody ratio, or DAR, is 2. As you can see, we continue to build momentum and advance our pipeline of innovative product candidates. We would now be happy to open the call for questions. Operator?