Telix's TLX66 meets objectives in AL amyloidosis safety trial

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Telix Pharmaceuticals (ASX:TLX) has announced that its bone marrow conditioning investigational candidate TLX66 has met the objectives of a phase I/IIa trial in demonstrating the initial safety profile in patients with AL amyloidosis.

The TRALA trial (Targeted Radiotherapy for AL Amyloidosis) is evaluating the safety and toxicity of TLX66 (90Y-besilesomab) as the sole bone marrow conditioning agent prior to autologous hematopoietic stem cell transplantation (HSCT) in patients with AL amyloidosis. 

The trial was sponsored by the University of Southampton Hospital in the UK and run across four centres in the country.

The company said that in total, nine patients with AL amyloidosis were enrolled into the trial and received TLX66 as the sole bone marrow conditioning agent prior to undergoing autologous HSCT.

"TLX66 demonstrated a favourable safety profile and was well tolerated in all nine patients, each of whom completed the trial," it said, adding, "All patients (100%) were successfully engrafted following bone marrow conditioning with TLX66 and autologous HSCT without any chemotherapy."

The company said disease response as measured by fall in clonal free light chains (FLC) was seen in seven out of the nine patients, with two complete responses (CR) and five partial responses (PR) within the first 100 days post-transplant. In two of the patients achieving PR, the clonal FLC continued to fall, with one patient achieving CR subsequently with no further treatment. In addition, a reduction in the measurable malignant plasma cells in the bone marrow was seen in six of eight evaluable patients. All patients remain alive at a median follow-up of 31 months (range 14 – 57 months).

According to chief medical officer Dr Colin Hayward, “The results from the TRALA trial indicate that TLX66 may offer a new approach to bone marrow conditioning in patients who could benefit from HSCT such as those with AL amyloidosis, providing new hope to patients with this rare disease and with few effective treatment options.

"TLX66 was well-tolerated, enabling successful engraftment of the patients’ own transplanted stem cells without the need for toxic chemotherapy. With all patients remaining alive, and most not requiring further therapy, we believe these data support taking TLX66 forward into a pivotal registration program in this rare disease indication.”

The company also announced that the first patient has been dosed in a clinical study in Japan using its investigational prostate cancer imaging product, Illuccix.

The study, which is an academic collaboration between Telix and Kanazawa University, will enrol ten patients with advanced prostate cancer and is the first clinical evaluation of gallium-based PSMA imaging in Japan. The objective is to obtain safety data in a representative Japanese patient population and to demonstrate that the targeting and biodistribution of TLX591-CDx in Japanese patients are consistent with international experience. The company said the clinical data may facilitate development planning discussions with the PMDA and other Asian regulators.