Calistoga Pharmaceuticals, developer of isoform-selective phosphatidylinositol 3 kinase (PI3K) inhibitors for the treatment of cancer and inflammatory diseases, closed a $40 million Series C financing.
The firm’s lead candidate is CAL-101, an oral, delta-selective PI3K inhibitor currently being evaluated as a single agent in patients with relapsed or refractory indolent non-Hodgkin lymphoma (iNHL), mantle cell lymphoma (MCL), and chronic lymphocytic leukemia (CLL). It is also being tested in combination with rituximab or bendamustine in patients with relapsed or refractory iNHL or CLL.
CAL-101 is a small molecule that exhibits a greater than 200-fold selectivity in cell-based assays for the delta isoform as compared to other class 1 PI3K isoforms, according to Calistoga.
Calistoga Pharmaceuticals is planning to advance CAL-101 into a registration program later this year. “With over one hundred patients enrolled in clinical trials evaluating CAL-101 over the past year, we are pleased with the impressive clinical results we have observed in these heavily pretreated patients with B-cell leukemias and lymphomas,” notes James Topper, M.D., Ph.D., chairman of the board of directors and general partner with Frazier Healthcare Ventures, a founding investor that also took part in the Series C round.
Results presented at this year’s ASCO demonstrated that single-agent CAL-101 treatment in patients with relapsed or refractory iNHL, MCL, and CLL led to overall response rates of 57%, 67%, and 30%, respectively. Furthermore, 94% of patients with CLL had greater than 50% decrease in their lymph node disease.
While CAL-101 was reportedly generally well tolerated, a low incidence of hematological toxicity was observed. Some patients had an asymptomatic elevation of transaminases, which was monitorable and reversible following discontinuation of dosing, Calistoga notes. Most patients resumed CAL-101 at a reduced dose.
The company will also use part of the Series C financing to advance its preclinical pipeline as well as CAL-263 into Phase II studies for the treatment of patients with inflammatory diseases. CAL-263 is also a delta-selective PI3K inhibitor.