Introduction

Mutant KRAS is one of the most common oncogenic drivers, and is present in over 90 % of pancreatic as well as 30-40 % of lung and colorectal cancers. Until recently, decades of research aiming to target mutant KRAS isoforms directly, have been futile. Even now, after the emergence of isoform-specific KRAS^G12C- and KRAS^G12D-inhibitors, many isoforms, including the ones frequently associated with pancreatic ductal adenocarcinoma (PDAC), remain yet to be targeted. Furthermore, it has been shown that targeting RAS downstream effectors, like MEK or PI3K, alone induces adaptive mechanisms leading to tumor recurrence or resistance, and this might hold true for KRASi monotherapy as well. Here we report our findings regarding the combined inhibition of SHP2, a non-receptor tyrosine phosphatase upstream of KRAS, and ERK, a key serine/threonine kinase downstream of KRAS - a two-pronged approach at inhibiting the RAS-MAPK-Pathway.

Aims & Methods

The allosteric SHP2 inhibitor RMC-4550 and the ATP-competitive ERK inhibitor LY3214996 were used for all our in vitro and in vivo experiments. Murine and human PDAC cells were used to investigate in vitro growth inhibition, apoptosis induction and MAPK-pathway inhibition induced by RMC-4550 and LY3214996 alone or in combination. We then used an endogenous (KCP) and three transplantation-based mouse models to evaluate the in vivo efficacy and tolerability of RMC-4550 or LY3214996 monotherapy compared to the combination in different treatment regimens.

Results

The combination of RMC-4550 and LY3214996 shows synergistic anticancer activity, superior disruption of the MAPK pathway, and significantly increased apoptosis induction compared to single-agent treatments in human and murine PDAC cells in vitro. Moreover, we demonstrate good tolerability and efficacy of the combination in vivo, with significant tumor regression in multiple pre-clinical models of KRAS-driven PDAC of human and murine origin. We also saw preliminary evidence that ¹⁸F-FDG PET can be used to detect and predict early drug responses in animal models.

Conclusion

As a result of our findings, combined inhibition of SHP2 and ERK is currently under investigation in a clinical trial (SHERPA, SHP2 and ERK inhibition in pancreatic cancer, NCT04916236), in patients with KRAS-mutant NSCLC, CRC and PDAC.

Introduction

High-risk human papillomavirus (hr-HPV) has been suggested as a risk factor for oesophageal adenocarcinoma (OAC).^1-3 In HPV driven cancers (eg cervical malignancy), associated lymph nodes with a detectable viral load denote metastatic involvement.⁴ To date, there have been no reported studies regarding HPV involvement in lymph nodes of metastatic OAC.⁵

Aims & Methods

Formalin fixed surgically resected specimens were utilised in this study. Eight primary OAC and 16 associated metastatic lymph nodes were analysed for hr-HPV using droplet digital polymerase chain reaction (ddPCR). Viral load was determined and clinical data collected. Utmost care was undertaken to prevent cross-contamination.

Results

The mean age of the patients was 68.6 years. All patients had Siewert Class I or II tumours [T3N1-3,M0 (n=6), T4N3M0 (n=1), T1bN2M0 (n=1)]. 6/8 tumours were positive for hr-HPV DNA. All were genotype 18. There were no other hr-HPV genotypes detected in the primary cancer. The viral load ranged from 1 to 34 copy numbers per 10,000 cells in the primary tumour. 3/16 corresponding lymph nodes obtained from these 8 tumours were positive for hr-HPV; genotype 16 (n=1) and genotype 18 (n=2). These 3 hr-HPV DNA positive lymph nodes corresponded to 2 hr-HPV genotype 18 positive primary OAC. Viral load was measured to be 1 to 2 copy numbers per 10,000 cells in the metastatic lymph nodes.

Conclusion

This is the first time that hr-HPV has been detected in both the primary OAC and associated nodal metastases giving credence to the role of this pathogen in this malignancy.

References

1. Rajendra S, Wang B, Snow ET, et al. Transcriptionally active human papillomavirus is strongly associated with Barrett's dysplasia and esophageal adenocarcinoma. Am J Gastroenterol 2013; 108: 1082-93.
2. Wang B, Rajendra S, Pavey D, et al. Viral load and integration status of high-risk human papillomaviruses in the Barrett's metaplasia-dysplasia-adenocarcinoma sequence. Am J Gastroenterol 2013; 108: 1814-6.
3. Li X, Gao C, Yang Y, Zhou F, Li M, Jin Q, Gao L. Systematic review with meta-analysis: the association between human papillomavirus infection and oesophageal cancer. Aliment Pharmacol Ther 2014; 39: 270-81.
4. Kobayashi Y, Yoshinouchi M, Tianqi G, Nakamura K, Hongo A, Kamimura S, Mizutani Y, Kodama J, Miyagi Y, Kudo T. Presence of human papilloma virus DNA in pelvic lymph nodes can predict unexpected recurrence of cervical cancer in patients with histologically negative lymph nodes. Clin Cancer Res. 1998;4:979–983.
5. Sharma P, Gautam SD, Rajendra S. Importance of investigating high-risk human papillomavirus in lymph node metastasis of esophageal adenocarcinoma. World J Gastroenterol 2020; 26(21): 2729-273.

Introduction

Aims & Methods

Results

Conclusion

References

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