“Positive data” is being presented regarding the activity of Kazia Therapeutics’ (ASX: KZA) lead drug paxalisib in two forms of childhood brain cancers.
The company is presenting the data via two presentations this week at the 20th International Symposium on Pediatric Neuro-Oncology (ISPNO) in Germany.
Johns Hopkins University’s Dr Jeffrey Rubens spoke about the activity of paxalisib in combination with a second drug in animal models of atypical teratoid/rhabdoid tumours.
The second presentation is from Associate Professor Matt Dun at the Hunter Medical Research Institute within Australia’s University of Newcastle.
Dr Dun’s presentation covers work carried out in collaboration with 10 international laboratories and leading paediatric centres.
This work relates to the combination of paxalisib with ONC201, which is a Chimerix manufactured investigational therapy for treating diffuse intrinsic pontine glioma (DIPG).
‘Dramatic reduction’ of tumour
According to Kazia, diffuse midline gliomas (DMGs) are a group of childhood brain cancers that include DIPG, which is categorised as highly aggressive and hard to treat.
There are no United States Food and Drug Administration approved drug treatments for DMGs, which account for 15% of all brain tumours in children.
Additionally, from diagnosis, life expectancy is between nine and 11 months.
While ONC201 has demonstrated efficacy in DIPG, Kazia noted patients become resistant to the drug over time.
Under compassionate access, two patients who received a combination of ONC201 and paxalisib demonstrated “dramatic reductions in tumour volume and complete resolution of disease symptoms – extending overall survival”.
In two animal models of DIPG, paxalisib and ONC201 “synergistically extended survival” from 73 to 100 days and from 36 to 43 days.
This research prompted the clinical trial of the drug combination to begin in November last year.
The Pacific Pediatric Neuro-Oncology Consortium (PNOC) has sponsored the phase II trial, which is ongoing.
Initial data from this study is anticipated in the first half of 2023.
‘Leading cause of death’ in children
Dr Dun said while brain tumours are the second-most common form of cancer in children, they are the “leading cause of death” (cancer related), with the prognosis for aggressive forms of the disease including DIPG remaining “woeful”.
“It is vital that we find new treatments.”
“This research collaboration has united many of the leading international centres in this field and has deployed cutting edge research tools to identify an extremely promising combination of therapies.”
“My colleagues and I hope to see these laboratory findings validated in the ongoing PNOC clinical trial, which may establish ONC201 and paxalisib as the cornerstones of treatment for children and their families affected by this disease,” Dr Dun said.
Kazia’s lead drug paxalisib is a brain-penetrant inhibitor of the PI3K/Akt/mTOR pathway. The drug has initially been developed to treat glioblastoma, which is the most common and most aggressive primary brain cancer in adults.
The drug is part of the GBM AGILE clinical study for glioblastoma.
GBM AGILE is multi-drug platform study to identify “promising new therapies for glioblastoma”.
As well as paxalisib, two other drug candidates are participating in the study including Bayer’s regorafenib and Kintara Therapeutics’ VAL-083.