Rubius Therapeutics, a biotech firm that is genetically engineering red blood cells to pioneer a new class of cellular medicines called Red Cell Therapeutics, has announced initial clinical, pharmacodynamic and tumour trafficking data from its ongoing Phase I/II clinical trial of RTX-240 in patients with advanced solid tumours.
RTX-240 is an allogeneic, off-the-shelf cellular therapy product candidate designed to simultaneously present hundreds of thousands of copies of the costimulatory molecule 4-1BB ligand (4-1BBL) and IL-15TP (trans-presentation of IL-15 on IL-15Rα) in their native forms. RTX-240 is being investigated for its potential to broadly stimulate the immune system by activating and expanding both NK and memory T cells to generate a potent anti-tumour response.
Safety data from the trial revealed most common mild to moderate adverse events were fatigue, chills, nausea, decreased appetite and joint pain, each of which were reported in three patients.
Early results from the trials show that the treatment option indeed has the potential to reduce solid tumours, with efficacy data made available for 15 patients at the time of data cutoff on 28 February. Sixteen patients were evaluable for safety, the trial’s primary outcome measure.
The data includes one patient whose disease progressed while on anti-PD-L1 therapy. After starting Rubius’s red cell treatment, the patient saw a confirmed partial response with a 54% reduction in target lesions.
Another patient saw an unconfirmed partial response with complete resolution in the trial. Several other patients saw a halt in the progression of their cancer while on the treatment.
The company also shared tumour trafficking data from one patient with relapsed/refractory acute myeloid leukemia (AML) in the second Phase I arm of the study. The data showed that the trafficking of T and NK cells into the bone marrow was associated with increases in the cellularity of the marrow.
Rubius said this new data provides “initial proof-of-concept of the RED PLATFORM” by providing evidence that red blood cells can be engineered to mimic the human immune system and stimulate adaptive and innate immunity to generate clinical responses in cancer patients with refractory disease.
“These initial data are incredibly exciting and demonstrate that RTX-240 has the potential to generate single-agent activity in patients with solid tumours, including a cold tumour such as metastatic uveal melanoma, where other treatments have failed to induce responses in patients,” said Rubius Therapeutics chief medical officer Dr Christina Coughlin.
“The encouraging safety results, including a single event of Grade 1 liver toxicity, and preliminary efficacy data for RTX-240 to date give us the potential to realise the power of immune agonists for the treatment of cancer.”
The positive results from Rubius’s early-stage trials of the new cancer drug caused the company’s share price to surge by 84% following the data read-out on Monday.
“We believe these data provide clinical validation of our RED PLATFORM and de-risk our oncology pipeline of Red Cell Therapeutics,” said Rubius Therapeutics president and CEO Dr Pablo J. Cagnoni.
“Given the encouraging initial safety and preliminary efficacy data for RTX-240, we plan to initiate a Phase 2 expansion cohort in the first quarter of 2022, and a new Phase 1 arm of the ongoing RTX-240 clinical trial to evaluate RTX-240 in combination with anti-PD-1 therapy in patients with advanced solid tumours during the second half of 2021.”