Due to the registration potential of the mid-stage studies, the U.S. Food and Drug Administration requested the company complete a standard safety study, which amounts to a partial clinical hold on the study.
ALX Oncology has hit a slight hiccup in its plans to initiate a Phase II study pairing Merck’s Keytruda with its CD47 inhibitor in Head & Neck Squamous Cell Carcinoma (HNSCC). Due to the registration potential of the mid-stage studies, the U.S. Food and Drug Administration (FDA) requested the company complete a standard safety study, which amounts to a partial clinical hold on the study.
This morning, California-based ALX Oncology said the regulatory agency verbally informed the company of the need for a standard ongoing non-clinical safety study. The FDA noted that for any drug development program moving swiftly through development, this non-clinical study is still required prior to the initiation of a clinical trial that could be considered pivotal, the company said. The FDA’s request was not made in response to any safety concerns raised by ALX’s asset, the company noted.
In September, Merck and ALX partnered for two HNSCC studies. The first program will assess ALX148, an investigational next generation CD47 blocker, in combination with Merck’s checkpoint inhibitor as a potential first-line treatment for patients with PD-L1 expressing metastatic or unresectable, recurrent HNSCC. The second study will evaluate ALX148 in combination with Keytruda and standard chemotherapy for the first line treatment of patients with metastatic or unresectable, recurrent HNSCC.
ALX will be allowed to begin its planned Phase II studies with an enrollment cap of 50 patients who will be treated with the combination therapeutic across both studies pending acceptance of the non-clinical safety study report. ALX expects to provide the required report to the FDA prior to reaching the 50-patient enrollment cap. While this cap on enrollment is defined as a partial clinical hold, no delays are anticipated in the company’s current clinical study timelines, ALX noted.
Sophia Randolph, chief medical officer of ALX, said the company is on track to complete the standard ongoing non-clinical safety study and is pleased the FDA will allow the company to begin the planned Phase II studies of ALX148.
“We are excited to have demonstrated encouraging anti-tumor activity with ALX148 in combination treatment in patients with HNSCC as well as HER2-positive gastric and gastroesophageal junction cancer. We believe these indications, in addition to our myelodysplastic syndromes program (ASPEN-02), offer potential registration pathways in combination with existing approved therapies and we intend to accelerate ALX148 development in solid and hematological indications in 2021,” Randolph said in a statement.
ALX148 combines a high-affinity CD47 binding domain with an inactivated, proprietary Fc domain. ALX148 has demonstrated promising clinical responses across a range of hematologic and solid malignancies in combination with a number of leading anti-cancer agents. ALX Oncology recently announced that ALX148 in combination with Keytruda and chemotherapy achieved a 75% overall response rate, including a complete response, in a Phase Ib expansion cohort for the front-line treatment of patients with metastatic or unresectable, recurrent HNSCC who have not received prior treatment for their advanced disease. The company also reported recent ASPEN-01 data that ALX148 in combination with Keytruda achieved a 40% ORR in patients with second-line HNSCC who had never received a checkpoint inhibitor for their advanced disease.
Merck’s Keytruda was approved in 2019 as a monotherapy first-line treatment for patients with metastatic or with unresectable, recurrent HNSCC. The approval marked Keytruda as the first anti-PD-1 therapy approved in the first-line setting as monotherapy in patients whose tumors express PD-L1 or in combination with chemotherapy regardless of PD-L1 expression for patients with metastatic or with unresectable, recurrent HNSCC and the first anti-PD-1 therapy to demonstrate a statistically significant improvement in OS in these patients. Keytruda was initially approved for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy in 2016.
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