Development Of Resistance Mutations Research Articles

Abstract 3218: Combination drug screen identifies novel epigenetic therapies to enhance menin inhibitor efficacy in KMT2A rearranged and NPM1 mutant AML

Abstract Background: Acute myeloid leukemia (AML) with KMT2A-rearrangements have a poor prognosis and so there is an urgent need for novel therapies. Menin inhibitors have shown promising anti-leukemic effects in KMT2A-rearranged and NPM1-mutated AML. However, the efficacy of menin inhibitors as single agents may be limited by the development of resistance mutations. Combining menin inhibitors with other epigenetic drugs may present a strategy to enhance their therapeutic potential. In this study, we performed a combination drug screen using an epigenetic drug library in KMT2A-rearranged (MV4;11) and NPM1-mutant (OCI-AML3) AML cell lines to identify synergistic therapies that can be used in conjunction with menin inhibitors. Methods: During assay optimization, MV4;11 and OCI-AML3 cells were treated with the menin inhibitor DSP-5336, and their viability was assessed. Quality control metrics were applied with Z’ values consistently greater than 0.5 for all assay plates and then the cells were subjected to a small molecule compound library screen containing a set of 932 epigenetic drugs. The screening process included a systematic evaluation of each drug's effect on cell viability in combination with the DSP-5336. Results: The combination drug screen demonstrated robust performance in both MV4;11 and OCI-AML3 cell lines, with reliable quality control metrics. Among the epigenetic drugs tested, five compounds were identified as potential hits that synergistically enhanced the efficacy of DSP-5336 across both cell lines.The five identified compounds exhibited enhanced anti-leukemic effects when combined with the menin inhibitor in either one of the cell lines. The targets of these drugs varied, including histone deacetylases, histone acetyltransferases and BRD4 inhibition, suggesting many alternate mechanisms of action involving epigenetic modulation. Remarkably, one of the 5 hits C301-3161, a KAT2A inhibitor, showed limited activity in either cell line alone but increased cell killing with DSP-5336 in both cell lines, highlighting its potential as a specific therapeutic for combining with DSP-5336 in AML patients. Conclusions: Our findings suggest combining menin inhibitors with other epigenetic drugs may improve AML treatment outcomes. The combination drug screen successfully identified four novel compounds that synergistically enhance menin inhibitor efficacy in both KMT2A-rearranged and NPM1-mutant AML cell lines. These compounds hold significant promise as potential therapeutic candidates for further investigation. Future studies should focus on elucidating the underlying mechanisms of action for each hit and evaluating their effects in preclinical animal models. Ultimately, this research may pave the way for the development of innovative combination therapeutic strategies for AML patients with KMT2A-rearragned and NPM1-mutant AML. Citation Format: Tulasigeri M. Totiger, Sana Chaudhry, Skye Montoya, Maurizio Affer, Anya K. Sondhi, Alexandra Chirino, Claude-Henry Volmar, Shaun Brothers, Justin Watts, Justin Taylor. Combination drug screen identifies novel epigenetic therapies to enhance menin inhibitor efficacy in KMT2A rearranged and NPM1 mutant AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3218.

Palazestrant (OP-1250), A Complete Estrogen Receptor Antagonist, Inhibits Wild-type and Mutant ER-positive Breast Cancer Models as Monotherapy and in Combination.

The estrogen receptor (ER) is a well-established target for the treatment of breast cancer, with the majority of patients presenting as ER-positive (ER+). Endocrine therapy is a mainstay of breast cancer treatment but the development of resistance mutations in response to aromatase inhibitors, poor pharmacokinetic properties of fulvestrant, agonist activity of tamoxifen, and limited benefit for elacestrant leave unmet needs for patients with or without resistance mutations in ESR1, the gene that encodes the ER protein. Here we describe palazestrant (OP-1250), a novel, orally bioavailable complete ER antagonist and selective ER degrader. OP-1250, like fulvestrant, has no agonist activity on the ER and completely blocks estrogen-induced transcriptional activity. In addition, OP-1250 demonstrates favorable biochemical binding affinity, ER degradation, and antiproliferative activity in ER+ breast cancer models that is comparable or superior to other agents of interest. OP-1250 has superior pharmacokinetic properties relative to fulvestrant, including oral bioavailability and brain penetrance, as well as superior performance in wild-type and ESR1-mutant breast cancer xenograft studies. OP-1250 combines well with cyclin-dependent kinase 4 and 6 inhibitors in xenograft studies of ER+ breast cancer models and effectively shrinks intracranially implanted tumors, resulting in prolonged animal survival. With demonstrated preclinical efficacy exceeding fulvestrant in wild-type models, elacestrant in ESR1-mutant models, and tamoxifen in intracranial xenografts, OP-1250 has the potential to benefit patients with ER+ breast cancer.

Switching to Dolutegravir/lamivudine or Bictegravir/Emtricitabine/Tenofovir alafenamide. A comparative real-world study

Background This real-world study compared the safety and effectiveness of Dolutegravir/lamivudine (D/L) and Bictegravir/Emtricitabine/Tenefovir alafenamide (B/F/T) switch therapy regimens for people living with HIV (PLWH) Methods The retrospective study conducted from April 2019 to November 2022, included PLWH with < 50 copies/mL of HIV-RNA prior to recruitment who initiated either D/L or B/F/T switching therapy. The primary objective was to evaluate treatment discontinuation rates; safety and virologic outcomes were also evaluated. Results 690 PLWH were included, 358 in the D/L and 332 in the B/F/T, and a median follow-up of 728 and 1013 days, respectively. The discontinuation proportions were 8.7% (31 participants, incidence rate of 4.44 per 100 PYFU in the D/L group and 15.3% (51 participants, incidence rate of 6.25 per 100 PYFU) in the B/F/T group. The adjusted hazard ratio for B/F/T discontinuation compared to D/L was 1.20 (95% CI: 0.71;2.0; p = 0.494). Virologic failure (VL > 200 copies/mL in two consecutive measurements) occurred in 1.1% and 0.9% of patients in the D/L and B/F/T groups, respectively. Notably, one patient in D/L group with severe non-adherence and virologic failure developed resistance mutations. Conclusions Switching to either B/T/F or D/L treatment for PLWH was effective and well tolerated in this real-world study. Treatment discontinuation rates did not significantly differ between the two regimens.

Preclinical characterization of pirtobrutinib, a highly selective, noncovalent (reversible) BTK inhibitor

AbstractBruton tyrosine kinase (BTK), a nonreceptor tyrosine kinase, is a major therapeutic target for B-cell–driven malignancies. However, approved covalent BTK inhibitors (cBTKis) are associated with treatment limitations because of off-target side effects, suboptimal oral pharmacology, and development of resistance mutations (eg, C481) that prevent inhibitor binding. Here, we describe the preclinical profile of pirtobrutinib, a potent, highly selective, noncovalent (reversible) BTK inhibitor. Pirtobrutinib binds BTK with an extensive network of interactions to BTK and water molecules in the adenosine triphosphate binding region and shows no direct interaction with C481. Consequently, pirtobrutinib inhibits both BTK and BTK C481 substitution mutants in enzymatic and cell-based assays with similar potencies. In differential scanning fluorimetry studies, BTK bound to pirtobrutinib exhibited a higher melting temperature than cBTKi-bound BTK. Pirtobrutinib, but not cBTKis, prevented Y551 phosphorylation in the activation loop. These data suggest that pirtobrutinib uniquely stabilizes BTK in a closed, inactive conformation. Pirtobrutinib inhibits BTK signaling and cell proliferation in multiple B-cell lymphoma cell lines, and significantly inhibits tumor growth in human lymphoma xenografts in vivo. Enzymatic profiling showed that pirtobrutinib was highly selective for BTK in >98% of the human kinome, and in follow-up cellular studies pirtobrutinib retained >100-fold selectivity over other tested kinases. Collectively, these findings suggest that pirtobrutinib represents a novel BTK inhibitor with improved selectivity and unique pharmacologic, biophysical, and structural attributes with the potential to treat B-cell–driven cancers with improved precision and tolerability. Pirtobrutinib is being tested in phase 3 clinical studies for a variety of B-cell malignancies.

P670: ABSENCE OF BTK, BCL2, AND PLCG2 MUTATIONS IN RELAPSING CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) AFTER FIRST-LINE TREATMENT WITH FIXED-DURATION IBRUTINIB (I) PLUS VENETOCLAX (V)

Background: CAPTIVATE (PCYC-1142; NCT02910583) is a multicenter phase 2 study of first-line I+V in patients (pts) with CLL in 2 cohorts: Minimal Residual Disease (MRD) and Fixed Duration (FD). We previously reported that fixed-duration I+V provides deep, durable responses (Ghia et al, ASCO 2021; Wierda et al, J Clin Oncol 2021). Clinically-relevant mutations in BTK, PLCG2, and BCL2 have previously been reported in pts with progressive disease (PD) following single agent BTK or BCL2 inhibitor therapies. Such resistance-associated mutations may occur with increasing frequency after prolonged drug exposure. Fixed duration I+V is hypothesized to decrease the likelihood of developing resistance mutations and facilitate extended clinical benefit. Aims: We sought to ascertain presence or absence of resistance mutations at the time of PD in samples from pts treated with fixed-duration I+V in CAPTIVATE. Baseline genomic risk features and potentially prognostic mutations in CLL-related genes of interest were also evaluated in pts with and without subsequent PD. Methods: The analysis was conducted in 191 pts aged ≤70 y with previously untreated CLL who completed fixed-duration I+V, defined as 3 x 28d cycles of I then 12 cycles of I+V (I 420 mg/d orally; V ramp-up to 400 mg/d orally); this included pts from the FD cohort, and pts from the MRD cohort with confirmed undetectable MRD who received an additional cycle of I+V and were randomized to placebo. Samples from pts at the time of PD were evaluated for resistance mutations by targeted next-generation sequencing (NGS) using a custom-designed high-read-depth 100-gene panel (limit of detection 1% VAF, negative predictive value ≥95% assuming population prevalences <20%, for BTK, PLCG2, or BCL2 variants) in CD19-enriched peripheral blood (PB) or bone marrow. Mutations in additional genes of interest (Table) were evaluated by NGS using the Personalis ACE panel in baseline PB samples. Genomic risk features (Table) were also assessed at baseline. Mutations and genomic risk features evident at baseline were compared across PD and non-PD pts. Results: Baseline mutations in genes of interest and genomic risk features in 190 pts who completed fixed-duration I+V and with available baseline data are shown in the Table. Rates of mutations were similar between pts with (n=30) and without (n=160) subsequent PD. Of 30 pts with PD events (occurring between 16 and 53 mos after start of treatment), 22 (73%) had baseline mutations in genes of interest and 27 (90%) had ≥1 baseline genomic risk feature. Pts with PD generally had more baseline genomic risk features than pts without PD (median 3 vs 2; Wilcoxon P=0.02; analysis restricted to FD cohort pts to avoid bias). To date, 26 of 30 PD patient samples have been evaluated for mutations; no resistance-associated variants in BTK, PLCG2, or BCL2 were detected. Image:Summary/Conclusion: Earlier work has demonstrated a promising safety profile and efficacy of fixed-duration I+V in first-line CLL. Importantly, the current results show that no resistance-associated mutations in BTK, PLCG2, or BCL2 were identified in the pts with PD evaluated to date after first-line, fixed-duration I+V. The absence of such mutations at PD suggests that fixed-duration I+V treatment may offer the possibility of effective subsequent retreatment options with I and/or V and extend clinical benefit.

NEUROLOGICAL EVOLUTION OF A PATIENT WITH EGFR-MUTATED NON-SMALL CELL LUNG CANCER

TYPE: Case Report TOPIC: Lung Cancer INTRODUCTION: EGFR mutated NSCLC benefits from targeted therapy with TKIs, however between 50 and 70% of the treated patients will progress and nearly half of these will develop resistance mutations such as T790M, for which a third-generation TKI is available. Progression to the central nervous system is sadly a common feature in NSCLC patients, it impacts their quality of life and the one of their family as well as the management of the disease. CASE PRESENTATION: A patient with IV stage adenocarcinoma of the lung progressed after 21 months of first-line anti-EGFR therapy and showed clear signs of neurological impairment, later cytologically confirmed as caused by a carcinosis on cerebrospinal fluid. Liquid biopsy detected the resistance mutation T790M and therapy was switched with the third generation TKI Osimertinib. The first instrumental re-evaluation reports a partial response, with a reduction of lesions dimensions both in the lung and at the brain-level involvement. DISCUSSION: The clinical evolution of this case study documents the efficacy in the nervous system of a third generation anti-EGFR agent, Osimertinib, in addition to the already documented efficacy in the control and management of pulmonary malignancies. Of particular note is the initial positive response after three months of therapy. The significant reduction at brain level may hopefully be a sign that the rapid evolution usually seen in this type of patient can be curbed CONCLUSIONS: This case study documents the efficacy of Osimertinib in the control and efficacy at the level of the central nervous system in an NSCLC stage IV patient. DISCLOSURE: Nothing to declare. KEYWORD: THIRD-GENERATION TKI

Clinical Utility of Circulating Tumor DNA in Advanced Rare Cancers.

PurposePatients with advanced/relapsed rare cancers have few treatment options. Analysis of circulating tumor DNA in plasma may identify actionable genomic biomarkers using a non-invasive approach.Patients and MethodsRare cancer patients underwent prospective plasma-based NGS testing. Tissue NGS to test concordance was also conducted. Plasma DNA alterations were assessed for incidence, functional impact, therapeutic implications, correlation to survival, and comparison with tissue NGS.ResultsNinety-eight patients were analyzed. Diseases included soft-tissue sarcoma, ovarian carcinoma, and others. Mean turn-around-time for results was 9.5 days. Seventy-six patients had detectable gene alterations in plasma, with a median of 2.8 alterations/patient. Sixty patients had a likely pathogenic alteration. Five received matched-therapy based on plasma NGS results. Two developed known resistance mutations while on targeted therapy. Patients with an alteration having VAF ≥5% had a significantly shorter survival compared to those of lower VAF. Tissue NGS results from eleven of 22 patients showed complete or partial concordance with plasma NGS.ConclusionPlasma NGS testing is less invasive and capable of identifying alterations in advanced rare cancers in a clinically meaningful timeframe. It should be further studied as a prospective enrollment assay in interventional studies for patients with rare advanced stage cancers.Clinical Registration[https://www.umin.ac.jp/ctr/index-j.htm], identifier UMIN000034394.

Drug resistance mutations in protease gene of HIV-1 subtype C infected patient population.

Failure of antiretroviral therapy (ART) in HIV-1 infection is a critical issue for the physicians treating HIV patients. The major cause of drug failure is the development of resistance mutations in reverse transcriptase (RT) and/or protease (PR) genes. Mutations associated with drug resistance decrease drug effectiveness. This study was conducted to assess drug resistance profile of the entire PR gene in 90 HIV-1 patients consisting of 23 ART non-responsive, 32 ART responsive and 35 drug naive patients. It was observed that the majority of the sequences (94.4%) belonged to subtype C and (5.5%) to subtype A1. The ART non-responsive and responsive patients were treated with either first line of ART regimen (two NRTI and one NNRTI) or second line of ART regimen that included additional one protease inhibitor (PI). All the patients in each group except one responsive patient had various minor resistance mutations. Thus, drug failures in ART non-responsive patients may not always be due to drug resistance mutations instead other factors may also be responsible for drug failures such as non-compliance, suboptimal dose or drug interaction. The presence of minor drug resistance mutations in drug naive patients is suggestive of transmitted resistance mutations.

A retrospective analysis examining the use of tissue-based and blood-based NGS in patients (pts) with advanced non-small cell lung cancer (NSCLC).

e21195 Background: Next generation sequencing (NGS) of tumor has become an integral part of cancer diagnostics and therapeutics today. While tissue-based (TB) NGS is still considered gold-standard, cell-free DNA NGS obtained from peripheral blood (blood-based or BB) offers many advantages because of its quicker turnaround time, minimally-invasive nature and ability to address tumor heterogeneity and track development of resistance mutations over time. It however does have its disadvantages, predominant of which is its lower sensitivity. Integration of BB and TB NGS can both optimize turnaround time and increase detection of targetable mutations. Methods: We conducted a single institution, IRB approved, retrospective study evaluating NGS testing patterns in patients with advanced NSCLC treated at our institution between 1/1/16 and 3/31/20. Our primary endpoint was to evaluate the number of patients who had BB NGS performed at any point during their clinical course in addition to TB NGS testing. Our secondary endpoint was to evaluate the number of patients for who BB NGS led to change in treatment plan. Exploratory points included the concordance rate between BB and TB NGS performed within 1 month of each other and the details of discordance if any. Results: There was a total of 437 eligible advanced NSCLC patients who were treated at our institution between January 2016 and March 2020. Out of these, 104 (23.8%) had BB NGS performed at some point in their disease course. The median number of BB NGS testing done for these patients was 2 and ranged from 1 to 4. 32/104 (30.8%) of patients had change in management because of BB NGS results. TB and BB NGS were performed within one month of each other in 52 patients. 11 of these (21.2%) had detection of identical actionable mutations (AM) on both BB and TB NGS assays. 5 of the patients (9.6%) had AM detected on TB NGS alone and 6 of the patients (11.5%) had AM detected on BB NGS alone. 30/52 patients (57.7%) had no AM identified on both BB and TB NGS. Conclusions: BB NGS has added tremendous value to diagnosis and treatment of NSCLC. It is increasingly used in practice, in tandem with TB NGS. Nearly a fourth of our patients had BB NGS performed at some point in their clinical course. Nearly 20% of simultaneously performed BB and TB NGS were discordant and an AM was identified in only one of the biopsies. Although further research is needed, our study supports simultaneous BB and TB testing at diagnosis and progression thereby maximizing therapeutic potential.

Repurposing potential of posaconazole and grazoprevir as inhibitors of SARS-CoV-2 helicase

As the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic engulfs millions worldwide, the quest for vaccines or drugs against the virus continues. The helicase protein of SARS-CoV-2 represents an attractive target for drug discovery since inhibition of helicase activity can suppress viral replication. Using in silico approaches, we have identified drugs that interact with SARS-CoV-2 helicase based on the presence of amino acid arrangements matching binding sites of drugs in previously annotated protein structures. The drugs exhibiting an RMSD of ≤ 3.0 Å were further analyzed using molecular docking, molecular dynamics (MD) simulation, and post-MD analyses. Using these approaches, we found 12 drugs that showed strong interactions with SARS-CoV-2 helicase amino acids. The analyses were performed using the recently available SARS-CoV-2 helicase structure (PDB ID: 5RL6). Based on the MM-GBSA approach, out of the 12 drugs, two drugs, namely posaconazole and grazoprevir, showed the most favorable binding energy, − 54.8 and − 49.1 kcal/mol, respectively. Furthermore, of the amino acids found conserved among all human coronaviruses, 10/11 and 10/12 were targeted by, respectively, grazoprevir and posaconazole. These residues are part of the crucial DEAD-like helicase C and DEXXQc_Upf1-like/ DEAD-like helicase domains. Strong interactions of posaconazole and grazoprevir with conserved amino acids indicate that the drugs can be potent against SARS-CoV-2. Since the amino acids are conserved among the human coronaviruses, the virus is unlikely to develop resistance mutations against these drugs. Since these drugs are already in use, they may be immediately repurposed for SARS-CoV-2 therapy.

Investigation of immune escape-associated mutations of hepatitis B virus in patients harboring hepatitis B virus drug-resistance mutations.

BACKGROUNDIt is unclear whether immune escape-associated mutations in the major hydrophilic region of hepatitis B virus surface antigen (HBsAg) are associated with nucleoside/nucleotide analog resistance.AIMTo evaluate the association between immune escape-associated mutations and nucleoside/nucleotide analog resistance mutations.METHODSIn total, 19440 patients with chronic hepatitis B virus infection, who underwent resistance testing at the Fifth Medical Center of Chinese PLA General Hospital between July 2007 and December 2017, were enrolled. As determined by sequence analysis, 6982 patients harbored a virus with resistance mutations and 12458 harbored a virus lacking resistance mutations. Phenotypic analyses were performed to evaluate HBsAg production, replication capacity, and drug-induced viral inhibition of patient-derived drug-resistant mutants with or without the coexistence of sA159V.RESULTSThe rate of immune escape-associated mutation was significantly higher in 9 of the 39 analyzed mutation sites in patients with resistance mutations than in patients without resistance mutations. In particular, these mutations were sQ101H/K/R, sS114A/L/T, sT118A/K/M/R/S/V, sP120A/L/Q/S/T, sT/I126A/N/P/S, sM133I/L/T, sC137W/Y, sG145A/R, and sA159G/V. Among these, sA159V was detected in 1.95% (136/6982) of patients with resistance mutations and 1.08% (134/12,458) of patients lacking resistance mutations (P < 0.05). The coexistence of sA159V with lamivudine (LAM) and entecavir (ETV)-resistance mutations in the same viral genome was identified during follow-up in some patients with drug resistance. HBsAg production was significantly lower and the replication capacity was significantly higher, without a significant difference in LAM/ETV susceptibility, in sA159V-containing LAM/ETV-resistant mutants than in their sA159V-lacking counterparts.CONCLUSIONIn summary, we observed a close link between the increase in certain immune escape-associated mutations and the development of resistance mutations. sA159V might increase the fitness of LAM/ETV-resistant mutants under environmental pressure in some cases.

Failure to bictegravir and development of resistance mutations in an antiretroviral-experienced patient

We present here one of the first cases of virological failure during treatment with bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF). On March 2019, an antiretroviral-experienced HIV-infected patient was admitted to hospital because of cerebral toxoplasmosis. After undergoing treatment with sulfadiazine-pyrimethamine for two weeks, the patient initiated a BIC/FTC/TAF treatment, with 6.01 HIV RNA Log copies/mL, and 37 CD4 cells/μL. After two months under antiretroviral therapy (ART), acute neurologic deterioration with epilepsy, right hemiparesis and dysphagia occurred, leading to nasogastric nutrition and treatment. After several weeks, virological failure was confirmed with 4.01 HIV RNA Log copies/mL and R263K and M184V resistance mutations were detected.

I.18-1 NTRK Fusion Proteins

We have a new approach to cancer therapy “the Agnostic Tumor” approach. Molecular mechanisms (DNA mutations, translocations, deletions, fusions, etc.) are now the ones responsible of the origin and behavior of most of the tumors, instead of the location of the tumor as we used to think. We are in the beginning of changing the focus of cancer therapy from a single organ to a molecular marker envision. One of the best examples are the NTRK fusion proteins, NTRK genes encode for the Trk-family proteins: TrkA, TrkB, and TrkC (encoded by NTRK1, NTTRK2, and NTRK3). Normally, the NTRK family plays a role in the development of the nervous system, however, NTRK fusions are also present in solid tumors as fusion proteins responsible for growth of cancer cells, and the presence of these oncogenes is associate with poor survival in lung cancers and other tumor types. It is not surprising that these oncogenes are present in several different tumors (They are actionable in at least 17 tumor types) including adults and children. These genomic alterations are becoming a great example why the tumor agnostic approach might be the new paradigm in fighting cancer. However, there are still many challenges ahead; first for example, the diagnostic of these genetic aberrations: we can do fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), reverse-transcriptase polymerase chain reaction (RT-PCR) and next generation sequencing (NGS) of DNA or RNA (or cfDNA in blood: liquid biopsies). Each of these approaches has strengths and weaknesses, but we also have to play this in the context of workups for other genetic abnormalities and keeping into consideration that tumor tissue specimen is very limited in many instances. Nowadays, for example, we do FISH for ALK and ROS-1 translocations, if we add three more FISH tests for each of the NTRK alterations (and maybe one more for RET fusions) will markedly increase the costs of workup in a lung cancer patient, and the gene fusion partner, that might become relevant, still might not be identified if we don’t have the right probe. RT-PCR is a great technique, but we will need a lot of primers (there are more than 60 NTRK fusions documented) to cover all the NTRK genetic abnormalities. Probably the solution is to develop better IHC? as we are doing for ALK translocations and hopefully get one day as IHC for ROS-1 and the other NTRK oncogenes so we can have a more cost-effective work up. A more practical approach might be to establish NGS in tissue or blood as the standard of care that can detect all these genetic alterations at once at the time of the diagnosis of the patient? Later we can do a more limited work up if we are looking for ALK and now NTRK resistant variants in patients that have failed treatment clinically. Nonetheless, for those who are not fans of NGS and don’t advocate this approach we can say that several NTRK 1-3 introns are not well covered by NGS. Then, we need to do whole genome gene sequencing to find them increasing the costs of the workup. These are some of the questions that remain open while we make all these diagnostic techniques more accurate and more cost effective. Some of these reasons are responsible to consider the treatment for NTRK challenging: how we can treat a patient if we can’t discover the genetic aberration? We are fortunate to have two agents: entrectenib and larotrectenib that have already been FDA approved for NTRK fusions with acceptable toxicities regardless of tumor type, patient age, and fusion type, and more data coming from other agents in development CEP-701, ARRRY-470 DS-6051b, TPX-0005. Probably LOXO 195 is the one that has been more studied for now and it’s able to rescue patients that develop resistance mutations during the treatment with larotrectenib or entrectinib.

Resistance to epidermal growth factor receptor tyrosine kinase inhibitors in mutated non-small cell lung cancer: new avenues and strategies to overcome resistance

The most common driver mutation in non-small cell lung cancer (NSCLC) is found within the tyrosine kinase domain of the epidermal growth factor receptor (EGFR). It commonly affects younger, female, and non-smoking patients. To date, there are five approved tyrosine kinase inhibitors (TKIs) for the treatment of EGFR-mutated NSCLC: erlotinib, gefitinib, the second-generation TKI afatinib and dacomitinib, and the third-generation TKI osimertinib. Sequencing TKI treatment or starting with osimertinib first are reasonable treatment strategies. Nevertheless, patients develop resistance to these TKIs, which can be primary or acquired. Primary resistance includes resistance mutations such as EGFR insertion 20, acquired resistance comprises the development of resistance mutations, activation of bypass signaling, or histological transformation into small cell lung cancer. This article summarizes the current landscape of treatment in EGFR-mutated lung cancer and discusses the different resistance mechanisms. It gives a perspective on novel EGFR TKIs and potential combination strategies to overcome resistance.

Symtuza® (DRV/c/FTC/TAF) en el tratamiento de inicio

The management of HIV infection is based on the administration of lifelong antiretroviral therapy (ART). Single-tablet regimens (STR) reduce pill burden and maximise long-term adherence. Cobicistat-boosted darunavir with emtricitabine and tenofovir alafenamide co-formulation (DRV/c/FTC/TAF), with trade name Symtuza®, is the first STR based on a protease inhibitor (PI). Symtuza® exhibits the efficacy, potency and high genetic barrier of DRV/c, positioning it as the drug of choice even in patients at risk of developing resistance mutations, in addition to the good safety profile of TAF and the advantages of an STR. Early ART initiation is also possible as baseline genotype and HLA-B5701 are not needed. It therefore represents a very good regimen for naive patients, in particular those at risk of poor adherence, and those with low potential risk for drug-drug interactions. Supplement information: This article is part of a supplement entitled “Co-formulated cobicistat-boosted darunavir, emtricitabine, and tenofovir alafenamide for the treatment of HIV infection”, which is sponsored by Janssen.

Darunavir/cobicistat maintains the effectiveness of darunavir/ritonavir in HIV-infected patients under mono or dual therapy

Objectives: Darunavir/ritonavir (DRV/r) in mono or dual therapy has proven efficacy in selected patients. The aim of this study was to evaluate the efficacy of switching from DRV/r to DRV/cobicistat (DRV/c) in patients under mono or dual therapy.Methods: This was a prospective multicenter cohort study of patients using DRV/r under mono or dual therapy plus lamivudine who changed to DRV/c maintaining the previous regimen. All patients had a controlled HIV viral load (<50 copies/ml) when switched and were examined every 12 weeks. The primary end-point was the percentage of participants without virological failure (VF) at week 48 in the intent-to-treat analysis. The CD4 cell count and concentrations of cholesterol, triglyceride, and creatinine were measured from baseline to week 48.Results: A total of 162 patients were included: 68.5% were men, and their mean age was 46 ± 12 years. Seventy (43.2%) patients were treated with DRV/r monotherapy, and 92 (56.8%) were treated with DRV/r plus lamivudine. The efficacy at week 48 was 95.1% (95% CI: 90.6%–97.5%) in the intent-to-treat analysis and 98.7% (95.5–99.6%) in the on-treatment analysis. Two VFs were documented but without development of resistance mutations. No significant changes were found in the lipid profile. Creatinine concentration increased significantly by 0.07 mg/dl (0.04–0.10, P < 0.001).Conclusions: Switching from DRV/r to DRV/c in patients under mono or dual therapy is safe and effective.

A New Potent NS5A Inhibitor in the Management of Hepatitis C Virus: Ravidasvir.

Chronic hepatitis C virus (HCV) is a worldwide health problem that can lead to liver cirrhosis, liver cell failure and numerous subsequent complications such as hepatocellular carcinoma. Till the near past, pegylated interferon was the standard of care therapy. However, it was associated with suboptimal success rates and many side effects. Thereafter, direct antiviral agents (DAA) appeared and played the key role in management of HCV. One of those recent DAAs is ravidasvir. It is a potent NS5A inhibitor that was formerly known as PPI-668. It is produced by the cooperation of Presidio pharmaceuticals and Pharco International pharmaceutical company. Since its first production, it has been enrolled in different successive clinical trials. Phase 1 and 2 trials confirmed its safety and tolerability and its great efficacy in suppressing viral loads in short periods. It has a pangenotypic activity with favorable pharmacokinetic properties. Ravidasvir inhibits the replication of HCV variants that develop resistance mutations for different DAA classes. Even more, HCV variants that had reduced susceptibility to ravidasvir are completely susceptible to other DAA. Finally, a large multicenteric registrational phase 3 clinical trial that included large percentages of difficult to treat patients (such as cirrhotic and interferon experienced patients) has been fully accomplished and proved great SVR12 rates. Ravidasvir is a potent new NS5A inhibitor with excellent safety and tolerability in management of genotype 4 HCV patients.

Precision medicine in ALK rearranged NSCLC: A rapidly evolving scenario.

The identification of anaplastic lymphoma kinase (ALK) rearrangements in 2-5% of non-small cell lung cancer (NSCLC) patients led to the rapid clinical development of its oral tyrosine kinase inhibitor (TKI). Crizotinib was the first ALK inhibitor approved and utilised in the treatment of ALK+ NSCLC patients in the second line setting first and subsequently in the first line one. Since then many other ALK inhibitors have been developed (ceritinib, alectinib, brigatinib, lorlatinib,etc) and the treatment paradigm of these patients has considerably drifted. The questions regarding their treatment at progression remains unanswered at the moment. Our review clarifies what it is the state of the art in the treatment of ALK rearranged NSCLC patients, highlights the mechanisms of primary and secondary resistance mutations and suggests a treatment algorithm based on specific primary resistance or acquired mutations. Studies that enrolled ALK+ NSCLC patients with locally advance or metastatic disease receiving treatment with ALK inhibitor, first or second line, were identified using electronic databases (MEDLINE, EMBASE, and Cochrane library). Trials were excluded if they were phase 1, enrolled less than 10 patients. Overall 1942 patients were included in our review. It confirms the role and the efficacy in first line of Alectinib but it highlights also that all the ALK inhibitors could play a crucial role during the patients' journey. Identifying the different mutations and utilising the most active ALK inhibitor depending on the "up-to-date" driven mutation is the way forward in the management of those patients. the review shows the rapid drifting in the management of ALK+ NSCLC patients and the importance of fully understanding and acknowledging the role of the resistance mutation, primary or acquired. We strongly advocate a comprehensive genomic approach in the management of ALK+ NSCLC patients who develop resistance mutations that are still targetable by a different ALK inhibitor.

ACTG A5353: A Pilot Study of Dolutegravir Plus Lamivudine for Initial Treatment of Human Immunodeficiency Virus-1 (HIV-1)-infected Participants With HIV-1 RNA

Limited data exist on initial human immunodeficiency virus type 1 (HIV-1) treatment with dolutegravir plus lamivudine. A5353 is a phase 2, single-arm, pilot study of once-daily dolutegravir (50 mg) plus lamivudine (300 mg) in treatment-naive participants with HIV-1 RNA ≥1000 and <500000 copies/mL. Exclusion criteria included active hepatitis B or major protease, reverse transcriptase, or integrase resistance. The primary efficacy measure was the proportion with HIV-1 RNA <50 copies/mL (FDA [US Food and Drug Administration] Snapshot) at week 24. Virologic failure (VF) was confirmed HIV-1 RNA >400 copies/mL at week 16/20 or >200 copies/mL at or after week 24. Dolutegravir levels and drug resistance testing were performed at VF. One hundred and twenty participants (87% male, median age 30 years, 37 (31%) HIV-1 RNA >100000 copies/mL) initiated study treatment. Median entry HIV-1 RNA and CD4 count were 4.61 log10 copies/mL and 387 cells/mm3. Virologic efficacy at week 24 was 108/120 (90%, confidence interval [83%, 95%]), with comparable results in the >100000 copies/mL and ≤100000 copies/mL strata, that is, 89% (75%, 97%) and 90% (82%, 96%), respectively. Three participants with VF, had undetected plasma dolutegravir at ≥1 time points; the M184V and R263R/K mutations developed in 1 participant. Two participants experienced grade 3 possible/probable treatment-related adverse events; none discontinued treatment due to adverse events. Dolutegravir plus lamivudine demonstrated efficacy in individuals with pretreatment HIV-1 RNA up to 500000 copies/mL in this pilot trial, but a participant developed resistance mutations. NCT02582684.

Drug resistance patterns following pharmacy stock shortage in Nigerian Antiretroviral Treatment Program

BackgroundFor patients on antiretroviral therapy (ART), treatment interruptions can impact patient outcomes and result in the accumulation of drug resistance mutations leading to virologic failure. There are minimal published data on the impact of an ART stock shortage on development of drug resistance mutations (DRMs). In this report, we evaluate data from patients enrolled in the Government of Nigeria National ART Program that were receiving treatment at the time of a national drug shortage in late 2003.MethodsWe conducted a cross-sectional evaluation of samples collected between December 2004 and August 2005 from ART patients in virologic failure that either had a treatment interruption or did not during the late 2003 drug shortage period at the Jos University Teaching Hospital (JUTH). Plasma virus was genotyped, sequence data were edited and analyzed, and mutation profiles were categorized to evaluate predicted drug susceptibility. Data were analyzed to examine factors associated with development of resistance mutations. A genotypic sensitivity score to the alternate recommended regimen was computed to assess drug susceptibility if regimens were changed.ResultsA total of 56 patients were included in this evaluation (28 interrupted, 28 uninterrupted). Patients in the interrupted group had more DRMs than those in the uninterrupted group (p < 0.001); interrupted patients were more likely than uninterrupted patients to have one or more TAM-2 mutations (57.1% interrupted vs. 21.3% uninterrupted; p = 0.04). There was a statistically significant difference in resistance to both d4T (53.7% interrupted vs. 17.9 uninterrupted; p = 0.011) and AZT (64.3% interrupted vs. 25.0% uninterrupted; p = 0.003) by drug interruption status. Examining genotypic sensitivity scores, we found that 67.9% of the interrupted patients, as compared to 25.0% of the uninterrupted patients, did not have full susceptibility to one drug in the regimen to which guidelines recommended they be switched (p = 0.001).DiscussionIn this small observational study, we found evidence of a difference in resistance profiles and ART susceptibility between those that were stocked-out of drug versus those that were not. We believe that these data are relevant for many other low- and middle-income countries (LMIC) that also experienced similar ART shortages as they rapidly scaled up their national programs.