Stage 3 trials of an experimental targeted cancer drug produced by AstraZeneca that includes a bacterial toxin shows promise in treating the most common cancer in children, B-cell acute lymphoblastic leukaemia (ALL). However, therapeutic benefits in the trial appear to be limited, because trial patients are quickly developing therapeutic resistance to the drug and relapse.
A US trial however has shown that resistance to the targeted toxin-based therapy can possibly be overcome by combining it with another leukaemia drug, (Moxe), thus increasing its efficacy in patients with relapsed and chemotherapy-resistant (refractory) ALL.
Elsewhere Pilot phase 2 trials involving 154 children’s hospitals across USA are underway to test combination treatment for ALL, its infant tolerability and long-term event-free infant survival. The trials use a cocktail of targeted chemotherapy drugs that work in three different ways to stop cancer cell growth; by killing the cells, by stopping them from dividing, or by stopping them from spreading.
There is still a long way to go before the long-term efficacy of targeted drug combinations are proven, accepted and licensed by the FDA in USA and the NHS in UK for treating infant leukaemia. Research clinicians however are showing significant progress in harnessing the body’s own defence system by using modified T-cell based therapy to attack and kill cancer cells in both ALL and other cancers; a radically different approach to previous conventional chemotherapy treatments.
Genetically modified so-called chimeric antigen receptor (CAR) T-cells are showing remarkable efficacy for the treatment of chemotherapy resistant relapsed B-cell ALL, and other cancers, although tumour cells still adapt to evade even this new type of treatment. It is hoped that selecting the right combination of therapies will limit the ability of cancer cells to escape such combinatorial approaches to treatment.