Scott Koenig
Analyst · SVB Leerink. Your line is open
Thank you, Jim. Let’s begin with margetuximab, our investigational Fc optimized anti-HER2 antibody being evaluated in SOFIA, our Phase 3 trial in HER2-positive metastatic breast cancer designed to compare margetuximab plus chemotherapy against trastuzumab plus chemotherapy. We have previously reported that progression-free survival in the margetuximab arm was prolonged compared to the trastuzumab arm, meeting the study’s first sequential primary endpoint. In October, we reported data from the second prespecified interim analysis of overall survival conducted after 270 events had been reached. The data showed a trend in OS in favor of margetuximab. In the intent-to-treat population, the median OS of patients treated with margetuximab and chemotherapy was 21.6 months compared to 19.8 months for patients who received trastuzumab and chemotherapy, a prolonged median survival of 1.8 months. The hazard ratio was 0.89 and the P value was 0.33. Margetuximab’s optimized Fc region binds with increased affinity to CD16A, including the 158F low-affin V allele carried by approximately 85% of the human population. In the prespecificed exploratory analysis of this major subpopulation of genetically defined patients in SOFIA carrying the 158F allele, median OS was 23.7 months in the margetuximab arm compared to 19.4 months in the trastuzumab arm, a prolongation of 4.3 months. The haz ratio was 0.79 and the P value was 0.09. We look forward to presenting further details of the second interim analysis at the San Antonio Breast Cancer Symposium on December 11. The final OS analysis is planned after 385 events have accrued, and it is projected to be completed in 2020. We believe that patients with HER2-positive metastatic breast cancer need access to new therapies. Margetuximab, if approved by regulators, will address an important unmet need and could become a valuable treatment option for patients living with this devastating disease. Therefore, we expect to submit a BLA to the FDA before the end of the year. We also seek to address unmet needs of HER2-positive cancers beyond breast cancer. At the ESMO Congress in September, we presented updated data from our ongoing Phase 2 study evaluating margetuximab in combination with pembrolizumab in second-line patients with HER2-positive metastatic gastric cancer. This study is testing a chemotherapy-free regimen for patients who had received prior first-line standard-of-care therapy with chemotherapy and trastuzumab. As a reference, a response rate of 47% with a median overall survival of 13.1 months was reported from the first-line chemotherapy in trastuzumab in the ToGA study. In our Phase 2 study in second-line gastric cancer patients who are HER2 IHC-3 positive, we reported a median overall survival of 16.8 months. Furthermore, in the HER2 IHC-3-plus and PD-L1 double positive patients, we observed a median overall survival of 20.5 months and a response rate of approximately 50%. Notably, the safety profile of margetuximab and pembrolizumab observed in our study was similar to that of pembrolizumab monotherapy. Based on those promising second-line data, we have advanced the chemo-free regimen of margetuximab and MGA012, our anti-PD-1 MAB, into a Phase 2/3 registration study called MAHOGANY in first-line patients with gastric cancer who are HER2 IHC3-plus and PDL-1 double positive. The first patient was dosed in October. This chemotherapy-free part of the study, which we refer to as Module A, is designed as a single-arm study to support a potential accelerated approval of this regimen in the U.S. based on a primary efficacy endpoint of objective response rate. We believe there may be a significant opportunity to change the treatment paradigm for some patients living with metastatic HER2-positive gastric cancer. The second component of the MAHOGANY study, which we refer to as Module B, is designed as a randomized control trial to evaluate the combination of margetuximab with chemotherapy plus either MGA012 or MGD013, our PD-1 x LAG-3 DART molecule, compared to trastuzumab and chemotherapy in a broader population of patients with HER2-positive gastric cancer. The study is designed to evaluate overall survival as a primary endpoint. We expect to initiate Module B in the first half of 2020 and plan to coordinate the global efforts with our partner in greater China, Zai Lab. Turning briefly to enoblituzumab, the most advanced in our portfolio of molecules targeting B7-H3, enoblituzumab is an investigational MAB into which we have incorporated the same Fc mutations as margetuximab. We are planning a randomized Phase 2/3 study with enoblituzumab plus MGA012, with or without chemotherapy, in patients with first-line metastatic head and neck cancer. We expect to initiate the study shortly and plan to coordinate the global efforts with our partner in greater China, I-Mab Biopharma. The next program I will discuss is flotetuzumab, our investigational, bispecific DART molecule that recognizes both CD123 and CD3. As we announced this morning, there will be 5 presentations on flotetuzumab at the ASH annual meeting in December. These include 2 hour presentations of updated data from the Phase 1 monotherapy study in patients with relapsed or refractory acute myeloid leukemia, or AML. The study enrolled a total of 50 patients at the recommended Phase 2 dose, including 30 patients enrolled with refractory AML that will be the focus of the ASH presentation. These patients represent an extremely challenging population to treat where, based on our data, we believe there may be an opportunity to address an unmet need. The second oral presentation will describe data suggesting an immune signature associated with patients more likely to respond to flotetuzumab supporting a mechanism being exploited by this molecule. We have initiated discussions with the FDA to define a potential registration path for this molecule and anticipate providing further guidance early next year. We have also initiated a combination study of flotetuzumab and MGA012 in relapsed or refractory AML patients as a potential means to both broaden and lengthen the duration of response of AML patients on flotetuzumab. The combination is supported by a strong scientific rationale based on data that we have previously reported. Turning to our PD-1 program, the first and most advanced is MGA012, which as you know, is exclusively licensed to Incyte Corporation globally, although we retained the rights to develop our pipeline of molecules in combination with MGA012. Incyte is initially pursuing development of MGA012 monotherapy through 3 potentially registration directed clinical trials, one in MSI high endometrial cancer and one in Merkel cell carcinoma, with initial data anticipated in 2020 and a study in anal cancer with initial data expected in 2021. In addition, both Incyte and MacroGenics are each studying MGA012 in multiple combination trials. In total, the expanding development program for MGA012 includes approximately a dozen clinical studies. As you may have seen from the abstracts we released yesterday, Incyte has several poster presentations at the SITC annual meeting taking place this week. As a reminder, under the terms of our agreement with Incyte, MacroGenics is eligible to receive up to $405 million in potential development and regulatory milestones and up to $330 million in potential commercial milestones. If MGA012 is approved and commercialized, MacroGenics would be eligible to receive royalties tiered from 15% to 24% on future sales of MGA012 by Incyte. Our second checkpoint molecule is MGD013, a first-in-class investigational DART molecule that is designed to provide co-blockade of 2 immune checkpoint molecules expressed on T-cells, PD-1 and LAG-3. We have now enrolled approximately 150 patients in the Phase 1 dose expansion study in non-tumor types. We have observed some early signals of clinical activity with MGD013 monotherapy across several tumor types, which is very encouraging. The majority of patients, however, have not been followed long enough to be evaluated for an assessment of response. We plan to submit data from the study for presentation at a scientific conference in the first half of 2020. In summary, our most advanced programs are positioned to initiate or complete registration directed studies over the next year. As we head to the close of 2019, we look forward to presenting detailed results from the second interim analysis of OS in SOFIA and San Antonio breast and submitting the BLA to support registration of margetuximab as well as presenting flotetuzumab data at ASH. We would now be happy to address any questions that callers may have. Operator?