On December 7, 2020 Phosplatin Therapeutics LLC, a clinical stage pharmaceutical company focused on oncology therapeutics, reported that new data showing monotherapy treatment with PT-112, the company’s lead clinical agent, was feasible and well tolerated in heavily pre-treated, relapsed / refractory multiple myeloma patients (Press release, Phosplatin, DEC 7, 2020, View Source [SID1234572331]). The study entitled, "A Phase I Dose Escalation Study of PT-112 in Patients with Relapsed or Refractory Multiple Myeloma," was presented in a narrated slide presentation on December 5 at the 62nd American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition, taking place virtually from December 5-8, 2020.
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"The patients enrolled in this study have exhausted all currently available treatment options," said Taxiarchis Kourelis, M.D., Division of Hematology, Assistant Professor of Medicine, Mayo Clinic College of Medicine Rochester, Minnesota, who presented the study. "We are encouraged by these results, which show a well-tolerated safety profile and preliminary evidence of clinical activity that support further evaluation of PT-112 in a Phase II setting."
The study enrolled 24 patients using a 3+3 dose escalation design to determine the recommended Phase II dose. Patients received PT-112 as a monotherapy on a 28-day dosing cycle. All of the patients enrolled in the study were heavily pre-treated, having exhausted all available therapies. Key findings included the following:
PT-112 monotherapy treatment was feasible and well tolerated in this heavily pre-treated, relapsed / refractory multiple myeloma patient population, with one dose-limiting toxicity (grade 4 neutropenia, 420mg/m2) and no grade 4 non-hematological treatment-related adverse event observed.
The recommended Phase II dose (RP2D) of PT-112 was determined to be 360 mg/m2 given on days 1, 8, and 15 of a 28-day cycle.
Evidence of drug activity included a confirmed partial response in 1 of 4 patients treated at the RP2D, and a confirmed minimal response in a non-responding patient to prior BCMA-CAR-T therapy.
The study (NCT03288480) was designed and launched following translational work conducted in the Cancer Genetics Laboratory of P. Leif Bergsagel, M.D., at the Mayo Clinic in Scottsdale, Arizona.
"This evidence is very encouraging and supports our continued development of the PT-112 multiple myeloma program," said Robert Fallon, co-founder and Chief Executive Officer, Phosplatin Therapeutics. "We believe that PT-112’s immunogenic cell death induction, and osteotropic biodistribution, offers a compelling hypothesis for patients who have exhausted available treatment options. We look forward to expanding our study in the near future."
The presentation was part of "Session 653. Myeloma/Amyloidosis: Therapy, excluding Transplantation: Poster I" and is available on the ASH (Free ASH Whitepaper) Annual Meeting and Exposition site through the conclusion of the conference.
About PT-112
PT-112 is a novel small molecule conjugate of pyrophosphate that possesses a unique pleiotropic mechanism of action that promotes immunogenic cell death (ICD), through the release of damage associated molecular patterns (DAMPs) that bind to dendritic cells and lead to downstream immune effector cell recruitment in the tumor microenvironment. PT-112 represents the best-in-class small molecule inducer of this immunological form of cancer cell death and is currently under Phase II development. Further, PT-112 harbors a property known as osteotropism, or the propensity of the drug to reach its highest concentrations in certain areas of the bone, making it a candidate for treatment of patients with cancers that originate in, or metastasize to, the bone. The first in-human study of PT-112 demonstrated an attractive safety profile and evidence of long-lasting responses among heavily pre-treated patients and won "Best Poster" within the Developmental Therapeutics category at the ESMO (Free ESMO Whitepaper) 2018 Annual Congress. The combination Phase Ib study of PT-112 with PD-L1 checkpoint inhibitor avelumab in solid tumors was reported in an oral presentation at the ESMO (Free ESMO Whitepaper) 2020 Virtual Congress. The Phase I study in patients with relapsed or refractory multiple myeloma presented at ASH (Free ASH Whitepaper) is the third completed Phase I study of PT-112.