The paradox-breaking panRAF plus SRC family kinase inhibitor, CCT3833, is effective in mutant KRAS-driven cancers

BACKGROUND

KRAS is mutated in ∼90% of pancreatic ductal adenocarcinomas, ∼35% of colorectal cancers and ∼20% of non-small-cell lung cancers. There has been recent progress in targeting G12CKRAS specifically, but therapeutic options for other mutant forms of KRAS are limited, largely because the complexity of downstream signaling and feedback mechanisms mean that targeting individual pathway components is ineffective.

DESIGN

The protein kinases RAF and SRC are validated therapeutic targets in KRAS-mutant pancreatic ductal adenocarcinomas, colorectal cancers and non-small-cell lung cancers and we show that both must be inhibited to block growth of these cancers. We describe CCT3833, a new drug that inhibits both RAF and SRC, which may be effective in KRAS-mutant cancers.

RESULTS

We show that CCT3833 inhibits RAF and SRC in KRAS-mutant tumors in vitro and in vivo, and that it inhibits tumor growth at well-tolerated doses in mice. CCT3833 has been evaluated in a phase I clinical trial (NCT02437227) and we report here that it significantly prolongs progression-free survival of a patient with a G12VKRAS spindle cell sarcoma who did not respond to a multikinase inhibitor and therefore had limited treatment options.

CONCLUSIONS

New drug CCT3833 elicits significant preclinical therapeutic efficacy in KRAS-mutant colorectal, lung and pancreatic tumor xenografts, demonstrating a treatment option for several areas of unmet clinical need. Based on these preclinical data and the phase I clinical unconfirmed response in a patient with KRAS-mutant spindle cell sarcoma, CCT3833 requires further evaluation in patients with other KRAS-mutant cancers.

Gradient analysis of the distribution of mammals in Stage III of Kakadu National Park, with a review of the distribution patterns of mammals across north-western Australia

A total of 56 native mammal species (about one quarter of the species of land mammals known from Australia) was recorded from the Stage III area of Kakadu National Park, Northern Territory. A single environmental gradient (of substrate and disturbance) described well the distributions of species other than bats from this area. For most species, there was little shift in gradient position between three trapping periods (spaced over three years). The mammal fauna comprised a rocky upland assemblage, a lowland monsoon rainforest-swamp assemblage, and an open forest-woodland assemblage. Mammal diversity and abundance was greatest in the rocky uplands. The distribution of most bat species was not clearly associated with this gradient. The Stage III mammal fauna is compared with that described from elsewhere in north-western Australia. Across this region, the fauna shows little variation with longitude, but undergoes substantial latitudinal change in conjunction with a steep rainfall gradient. The habitat reSationships of the Stage III mammal fauna are broadly repeated across north-western Australia. The fauna of sandstone ranges is attenuated with decreasing size and increasing isolation of these ranges. The mammal fauna of monsoon rainforests is depauperate, reflecting the small size and patchiness of this habitat. The mammal fauna of open forest/woodland is characterised by extensive distributions of its constituent species and a relative lack of arboreal folivores and small macropods.

Effect of vitamin A on rat hepatic mixed-function oxidases, glutathione transferase activity and generations of oxygen radicals

Rat hepatic microsomal mixed-function oxidase activities were not significantly affected by vitamin A deficiency. Similarly cytosolic glutathione S-transferase and glutathione reductase activities as well as total glutathione levels were unaffected by the vitamin A status. Induction of the mixed-function oxidases by 3-methylcholanthrene or phenobarbitone was independent of the vitamin A status. No significant differences in microsomal chemiluminescence, before and following challenge with tertiary butyl hydroperoxide, were evident between the vitamin-A-deficient animals and those maintained on vitamin-A-supplemented diets. The present findings indicate that the protective action of vitamin A against chemical carcinogens is unlikely to involve modulation of the enzyme systems responsible for their metabolism.