TELIX: Acceleration of Prostate Cancer Therapy Program
Updated: Feb 18, 2021
Synopsis: In conjunction with the completion of the acquisition of Atlab Pharma SAS (ASX release: 11/09/18) Telix instigated an audit of the historical academic data for huJ591 (the “parent” antibody to Telix’s prostate therapy program). The high-level data from several academic Phase I and II studies has been previously published in a peer-reviewed setting, however much of the clinical detail remains undisclosed. Analysis of the data and independent monitoring by a third-party Clinical Research Organization (CRO) is strongly supportive of taking huJ591 into a Phase III study under certain dosing conditions (fractionated dosing), subject to regulatory approval. In doing so, Telix is potentially able to accelerate its antibody-directed prostate cancer radiotherapy program by approximately two years. Certain commercial opportunities underpin this decision.
Key points for investors:
The complete and detailed analysis of existing huJ591 data clearly informs the basis of a Phase III trial design in a well-defined patient population and is an opportunity for Telix to accelerate an important commercial inflection point for the Company. • In particular, the impressive durability of response in a clinically and commercially-important patient population (chemotherapy naïve metastatic castrate-resistant prostate cancer) is highly promising (n=54 patients). Initial results demonstrate a 48+ months median overall survival (OS) recorded in the highest dose cohort with a well-tolerated toxicity profile. This compares very favorably to competing programs. • Recent commercial momentum in the metastatic prostate radiotherapy setting strongly underpins this decision, including the FDA’s approval for Endocyte Inc. to commence the Phase III VISION trial (first patient enrolled in June ’18) and the subsequent acquisition of Endocyte by Novartis for USD $2.1Bn (October ’18).
Acceleration of Prostate Cancer Therapy Program Melbourne (Australia) – 8th January 2019.
Telix Pharmaceuticals Limited (ASX:TLX) (“Telix”, the “Company”), an Australian biopharmaceutical company focused on the development of diagnostic and therapeutic products based on targeted radiopharmaceuticals or “molecularly-targeted radiation” (MTR), today announced a strategy update for the TLX591 (prostate therapy) program. Audit of Weill Cornell 177Lu-huJ591 Data Concurrent with the completion of the acquisition of Atlab Pharma SAS (ASX release: 11/09/18) Telix engaged a third-party Clinical Research Organization (CRO) to audit and monitor the clinical data acquired by Weill Cornell Medical Centre (WCMC)1 for 177Lu (lutetium)-huJ591. HuJ591 is a humanized anti-PSMA2 monoclonal antibody (mAb) that has been extensively studied as a targeting agent in several hundred patients, including 217 patients for targeted radionuclide therapy in multiple Phase I and II studies. HuJ591 is one of the most widely studied targeting agents in radionuclide therapy for prostate cancer. Via the acquisition of Atlab, Telix has certain commercial radiotherapy rights to huJ591. The focus of the audit was prior clinical experience with fractionated (repeat dosing) of 177Lu-huJ591. Fractionated dosing enables the hematologic (blood/marrow) toxicity typically associated with antibody-directed radiotherapy to be ameliorated. A high-level summary of this data has been previously published in a peer-reviewed setting3 but the clinical detail remains largely undisclosed. HuJ591 Fractionated Data: Analysis The analysis of the audited WCMC huJ591, which includes extensive patient follow-up (to Dec ’18) and survival analysis, has confirmed several key findings. An interim analysis report has been issued to Telix with a fully monitored (quality assured) database due at the end of March ‘19.
The key findings are: • 177Lu-huJ591 is well tolerated, particularly with fractionated dosing at or below 45mCi/m2. • Other than manageable hematologic toxicities, no other off-target (i.e. salivary/lacrimal gland) effects were observed. • The median OS of metastatic castrate-resistant prostate cancer patients with significant disease burden compares favorably to previously reported survival benefit of competing programs, such as the PSMA-617 program (Endocyte/Novartis)4, In particular the highest dose cohorts (2x40mCi/m2 and 2x45mCi/m2) demonstrated a durable OS of over 40 months (n = 36 patients), reaching 48.4 months for the highest dose cohort (n = 16 patients). • The survival benefit of 177Lu-huJ591 in chemotherapy naïve (pre-chemo) patients is approximately twice that of patients that received end-stage chemotherapy (e.g. docetaxel). • The data is sufficiently robust to inform target patient population inclusion/exclusion criteria, biomarker measures such as PSA level, tumor burden and PSMA expression levels determined from PET imaging and the dosing regimen for a Phase III trial.
1 and collaborating institutions 2 PSMA = Prostate-Specific Membrane Antigen, a target expressed by the majority of prostate cancers 3 Tagawa et al. Journal of Clinical Oncology 2016 34:15_suppl, 5022-5022 (ASCO abstract) 4 Data from the German multi-center trial for PSMA-617 - Rahbar et al. Clin Nucl Med. 2016 Jul;41(7):522-8