June 3, 2008 — Calando Pharmaceuticals says it has dosed the first patient with CALAA-01, a targeted nanoparticle therapeutic. This represents the first siRNA therapeutic to enter the clinic in oncology and the first targeted delivery of any RNA interference, or RNAi product.

RNAi is a naturally-occurring mechanism within cells for selectively silencing and regulating specific genes. The ability to silence genes selectively through RNAi could provide a new class of medicines to treat a wide range of human diseases.

Calando, a majority-owned subsidiary of Arrowhead Research Corporation, says the patient successfully completed the first dosing cycle, which includes four doses over two weeks, of CALAA-01 in the first clinical trial using systemically-delivered nanoparticle therapeutic siRNA to treat cancer. CALAA-01 is a targeted nanoparticle, comprised of a proprietary, non-chemically-modified siRNA against the M2 subunit of ribonucleotide reductase—a clinically-validated cancer target—formulated with Calando’s RONDEL (RNAi/Oligonucleotide Nanoparticle Delivery) polymer delivery system. The first patient was enrolled and dosed at South Texas Accelerated Research Therapeutics (START) in San Antonio, Texas.

This open-label, dose-escalation Phase I study in patients with solid tumors which are refractory to standard-of-care therapies is being conducted at the UCLA Jonsson Cancer Center (UCLA) in Los Angeles, California, and at South Texas Accelerated Research Therapeutics (START) in San Antonio, Texas. It is being led by Drs. Antoni Ribas (UCLA) and Anthony Tolcher (START).

“The initiation of this Phase I clinical trial of CALAA-01 is a hallmark for Calando and for the field of RNAi therapeutics,” said Calando CSO for siRNA delivery, Jeremy Heidel, Ph.D. “We look forward to the continued treatment of this patient and subsequent patients and the establishment of safety and efficacy profiles for CALAA-01 in humans.”